Note: Descriptions are shown in the official language in which they were submitted.
PF 70540 CA 02791220 2012-08-27
1
Process for producing aqueous dispersions of thermoplastic polyesters
Description:
The present invention relates to a process for producing aqueous dispersions
of
thermoplastic polymers which have a plurality of ester groups and/or carbonate
groups
in the main polymer chain and which have an acid number of less than 5 mg
KOH/g, in
particular at most 3 mg KOH/g, and which have a zero-shear viscosity too (180
C) of at
least 60 Pa=s at 180 C. The invention also relates to the polymer dispersions
obtainable by said process, and to the use thereof.
Aqueous dispersions of thermoplastic polymers which have a plurality of ester
groups
and/or carbonate groups in the main polymer chain and which have an acid
number of
at most 10 mg KOH/g, in particular polyesters, and specifically biodegradable
polyesters, are of particular interest for many applications, in particular as
binders.
Unlike aqueous polymer dispersions in which the main chain of the polymer is
composed of carbon atoms, aqueous dispersions of polymers which have a
plurality of
ester groups and/or carbonate groups in the main chain of the polymer cannot
generally be produced by an emulsion-polymerization process. Instead, it is
usually
necessary to produce polymers of this type by a polycondensation route and
then to
convert them to an aqueous dispersion. In principle, there are many ways of
doing this.
Firstly, a solution of the polymer in an organic, preferably water-miscible,
solvent can
be mixed with the aqueous dispersion medium, and the organic solvent can in
turn be
removed. However, it is generally not possible to achieve complete removal of
the
organic solvents without accepting some loss of quality of the dispersion, for
example
caused by molecular-weight degradation of the polymer due to hydrolysis,
and/or by
destabilization of the disperse phase.
Polymers with a high acid number can in turn be emulsified in water, by using
a base to
alkalinify the aqueous dispersion medium, with the aim of deprotonating the
carboxy
groups and thus promoting self-emulsification of the polymer. This type of
procedure is
described by way of example in WO 98/12245. The process described in that
document is naturally not applicable to the production of aqueous dispersions
of the
polymers defined in the introduction, because they have a low acid number.
Another possibility consists in emulsifying a melt of the polymer in the
aqueous
dispersion medium, and then cooling. However, there is the risk here that
molecular-
weight degradation will occur under these conditions, caused by hydrolysis of
the ester
groups or of the carbonate groups in the main chain of the polymer.
PF 70540 CA 02791220 2012-08-27
2
EP 1302502 Al describes a process for producing aqueous dispersions of
biodegradable polyesters, by using a kneading process to incorporate a melt of
the
polyester into an aqueous solution of a surfactant substance which has low
surface
tension. Care has to be taken here that the ratio of the viscosity (zero-shear
viscosity
qo) of the polymer melt does not deviate too greatly from the viscosity of the
aqueous
solution, since otherwise the dispersions obtained are not stable. The result
of this is
firstly that it is only possible to produce high-viscosity dispersions of the
polyester with
viscosity values above 2 Pa-s, and secondly that the polyesters that can be
used are
only those having sufficiently low zero-shear viscosity rlo at the
incorporation
temperature. However, the performance characteristics of polyesters of that
type are
unsatisfactory for many purposes. Furthermore, molecular-weight degradation of
the
polyester frequently occurs under these conditions.
US 2005/058712 in turn describes a process for producing aqueous dispersions
of
biodegradable polyesters, by emulsifying a melt made of a mixture of the
polyester with
an additive that reduces melt viscosity, e.g. triacetin, in an aqueous
solution of a
surfactant substance. However, the disadvantage has proven to be the addition
of the
additive that reduces melt viscosity, which naturally remains within the
dispersion, with
resultant impairment of performance characteristics. Furthermore, the only
polyesters
that can be emulsified in this way are those whose zero-shear viscosity 'no is
sufficiently
low at the incorporation temperature. However, the performance characteristics
of
polyesters of that type are unsatisfactory for many purposes.
US 2002/0076639 describes inter alia the production of aqueous polyester
dispersions
of end-group-modified polyesters which have carboxylic acid groups and which
have
an acid number that is preferably from 7 to 70 mg KOH/g of polyester, via melt-
emulsification, using a rotor-stator mixer. The acid number gives the
polyester particles
amphiphilic character, which promotes emulsification. The use of the rotor-
stator mixer
here serves to produce spherical polyester particles.
US 6,521,679 describes the production of polyester dispersions of water-
insoluble
polyesters via melt-emulsification of mixtures of the water-insoluble
polyester with
water-soluble polyester resins which have from 0.1 to 1.5 mmol of sulfonic
acid groups
per gram of the water-soluble polyester. The melt-emulsification process uses
an
extruder and gives high-viscosity dispersions, which can be diluted with
water. The
water-insoluble polyesters used have low zero-shear viscosity.
It is therefore an object of the present invention to provide a process for
producing
aqueous dispersions of the polymers defined in the introduction. In
particular, the
process should allow polymers which have a plurality of ester groups and/or
carbonate
groups in the main polymer chain to be converted to an aqueous dispersion
without
significant molecular-weight degradation.
PF 70540 CA 02791220 2012-08-27
3
It has now been found that, although they have comparatively high zero-shear
viscosity
Tlo(180 C), thermoplastic polymers of the type defined in the introduction can
be
emulsified in an aqueous dispersion medium even without addition of flow aids
and/or
without any significant increase in the viscosity of the aqueous phase, via
addition of
thickeners, if a composition of the polymer which is composed of at least 99%
by
weight of the polymer is introduced, at a temperature above the melting or
softening
point of the polymer, by means of an apparatus which comprises at least one
rotor-
stator mixer, into an aqueous dispersion medium which comprises at least one
surfactant substance, and the resultant aqueous emulsion of the polymer is
quenched.
Said object was therefore achieved via the process explained in more detail
below.
Accordingly, the present invention provides a process for producing aqueous
dispersions of thermoplastic polymers which have a plurality of ester groups
and/or
carbonate groups in the main polymer chain and which have an acid number of
less
than 5 mg KOH/g, in particular less than 3 mg KOH/g, and which have a zero-
shear
viscosity rlo (180 C) of at least 60 Pa-s, frequently at least 80 Pa-s, in
particular at least
100 Pa-s, e.g. from 60 to 20 000 Pa-s, in particular from 80 to 15 000 Pa-s,
and
specifically from 100 to 10 000 Pa-s, at 180 C, where a composition which
comprises
the polymer and which is composed of at least 99% by weight of the polymer is
introduced, at a temperature above the melting or softening point of the
polymer, into
an aqueous dispersion medium which comprises at least one surfactant
substance,
and the resultant aqueous emulsion of the polymer is quenched, which comprises
carrying out the introduction of the composition of the polymer into the
aqueous
dispersion medium in a mixing apparatus which has at least one rotor-stator
mixer.
The process of the invention is attended by a number of advantages. Firstly,
it permits
production of aqueous dispersions of thermoplastic polymers with the
properties
mentioned here, and these cannot be converted to aqueous dispersions by the
processes in the teaching of the prior art. The aqueous dispersions obtainable
by the
process of the invention and comprising the fusible polymers are therefore
novel and
are therefore equally provided by the present application.
Unlike in the processes of the prior art, neither the use of organic solvents
nor the
addition of means of reducing melt viscosity is required. The process of the
invention
moreover does not lead to, or does not lead to any significant, molecular-
weight
degradation of the type that would in principle have been expected on the
basis of the
ester functions or carbonate functions comprised within the main chain of the
polymers.
Furthermore, the process of the invention can produce low-viscosity
dispersions with
viscosity values of 2 Pas (Brookfield, 20 C, determined to DIN EN ISO 2555) or
lower,
and these viscosity values are even achievable at solids contents of 40% by
weight or
above.
= PF 70540 CA 02791220 2012-08-27
4
In the process of the invention, the thermoplastic polymer is introduced into
the
aqueous dispersion medium, in the case of an amorphous polymer this occurs at
a
temperature above the softening point of the polymer, and in the case of a
crystalline or
semicrystalline polymer this occurs above the melting point of the polymer.
The
softening point of amorphous polymers is the temperature corresponding to the
glass
transition temperature as can be determined by way of example by means of
dynamic
scanning calorimetry (DSC) to ASTM D3418 or preferably to DIN 53765, or via
dynamic mechanical analysis (DMA). The melting point is the temperature which
causes melting or softening of the polymer, and which can be determined in a
manner
known per se by means of dynamic scanning calorimetry (DSC) to DIN 53765 or
differential thermal analysis (DTA).
An amorphous polymer is a polymer which has less than 1 % by weight of
crystalline
regions. A crystalline or semicrystalline polymer is a polymer which has more
than 1 %
by weight of crystalline regions, in particular at least 5% by weight. The
degree of
crystallinity of a polymer can be determined in a manner known per se via X-
ray
diffractometry or via thermochemical methods, such as DTA or DSC in a manner
known per se.
In the invention, the introduction process takes place by means of a rotor-
stator
apparatus for the mixing of liquids (hereinafter also rotor-stator mixer).
Rotor-stator mixers are familiar to the person skilled in the art and in
principle comprise
all of the types of dynamic mixer where a high-speed, preferably rotationally
symmetrical, rotor interacts with a stator to form one or more operating
regions which in
essence have the shape of an annular gap. Within said operating regions, the
material
to be mixed is subjected to severe shear stresses, and high levels of
turbulence often
prevail in these annular gaps, and likewise promote the mixing process. The
rotor-
stator apparatus is operated at a relatively high rotational rate, generally
from 1000 to
20 000 rpm. This gives high peripheral velocities and a high shear rate, thus
subjecting
the emulsion to severe shear stresses, which lead to effective comminution of
the melt
and thus to very effective emulsification.
Among the rotor-stator mixers are, by way of example, toothed-ring dispersers,
annular-gap mills, and colloid mills.
Preference is given to those rotor-stator mixers which have means of
generating
cavitation forces. Means of this type can be elevations arranged on the rotor
side
and/or on the stator side, where these protrude into the mixing chamber and
which
have at least one area where the normal has a tangential fraction, examples
being
pins, teeth, or knives or coaxial rings with radially arranged slots.
PF 70540 CA 02791220 2012-08-27
The rotor-stator mixer preferably has, on the side of the rotor, at least one
toothed ring
arranged so as to be rotationally symmetrical, and/or at least one ring which
has radial
slots (tooth gaps) arranged so as to be rotationally symmetrical. Apparatuses
of this
5 type are also termed toothed-ring dispersers or toothed-ring dispersing
machines. In
particular, the rotor-stator mixer has, on the side of the rotor and also on
the side of the
stator, at least one toothed ring arranged so as to be rotationally
symmetrical, and/or at
least one ring with radial slots (tooth gaps), where the (toothed) rings on
the side of the
rotor and on the side of the stator are arranged coaxially and undergo mutual
intermeshing to form an annular gap.
In one particularly preferred embodiment, the rotor-stator mixer is a toothed-
ring
dispersing machine which has a conical stator with a concentric frustoconical
recess,
and which has a likewise concentric conical rotor, where the rotor protrudes
into the
frustoconical operating chamber of the stator in such a way as to form an
annular
operating chamber, into which teeth protrude on the side of the rotor and of
the stator,
and these are respectively arranged in the form of one or more, e.g. 2, 3, or
4 coaxial
toothed rings on the side of the rotor and of one or more, e.g. 1, 2, 3, or 4
coaxial
toothed rings on the side of the stator, in such a way that the toothed rings
undergo
mutual offset intermeshing.
Apparatuses of this type are known to the person skilled in the art by way of
example
from DE 10024813 Al and US 2002/076639, and are supplied by way of example by
Cavitron Verfahrenstechnik v. Hagen & Funke GmbH, Sprockhovel, Germany.
The width b of the operating chamber in the toothed-ring dispersing machines
of this
preferred embodiment is generally about equal to the tooth height. The stator
teeth and
the rotor teeth typically have rounded-off corners, and specifically not only
at the upper
ends of the tooth but also at the concave corners at the base of the tooth.
The teeth
have generally been finely polished and usually have an extremely smooth
surface.
Their design is typically mutually complementary, so that when teeth are
aligned, the
result is an undulating gap between the teeth, the width of the gap being
approximately
equal at all positions. The stator and the rotor are generally respectively
single-piece
components, i.e. the stator and rotor teeth have been molded onto the
component
internally to give a single piece. This means that no separate rings of teeth
are present,
and also therefore means that no foreign substances can settle thereunder, or
within
interstices. The rotor has usually been secured by securing means, typically
using
screw threads, to a rotor support, which has been attached in rotationally
fixed manner
to the shaft. There is generally a securing means, for example a screw thread,
pressing
the rotor onto the rotor support and pressing this onto a shaft casing, which
typically
surrounds a shaft and has axial bracing against the shaft. The unit made of
rotor
support and rotor can be removed from the shaft by releasing the securing
means.
PF 70540 CA 02791220 2012-08-27
6
Surrounding rotor and stator there is a housing, which has inlets for the
polymer melt
and the aqueous dispersion medium, and outlets for the dispersion. In one
particular
embodiment, that rear side of the housing that faces away from the inlet has
been
sealed by a rear wall, which has a passage for a shaft, and which typically
bulges into
an intermediate space. The passage for the shaft, or the passage for the shaft
casing,
has been sealed by a gasket arrangement, which preferably has an axial face
seal with
a fixed ring and a ring that rotates with the system. In one specific
embodiment, the
rear wall of the housing delimits an annular rear space which has been formed
behind
the rotor support and which is part of the housing.
The operating chamber between stator and rotor preferably has external radial
delimitation via a perforated wall of the stator. Typically, the perforated
wall comprises
numerous radially arranged holes. It preferably has a further surrounding
perforated
wall, which is a constituent of a ring secured on the rotor support. After
passage of the
teeth, when the rotor is rotated, the holes of the perforated walls of rotor
and stator
alternately coincide and narrow, time-limited jets of the liquid are thus
forced into an
annular space, which surrounds the rotor, and which has connection to the
optionally
present rear space.
If the rear space is present, its width between rotor support and the rear
wall of the
housing is preferably substantially greater than the width b of the operating
chamber.
The smallest width is found at the external periphery of the rear space, and
the
greatest width is found in the region near to the shaft. The securing means,
which also
secure the ring to the rotor support, preferably form, with their heads, pump
vanes
which can convey the liquid comprised within the rear space and can force it
onward.
Since the rate of rotation of the rotor in the operating condition is
relatively high,
generally from 1000 to 20 000 rpm, the result is not only a high shear rate
but also a
high level of centrifugal action, and the liquid is thus forced outward and
fed to the
outlet.
In the invention, the composition of the polymer is mixed with the aqueous
dispersion
medium at a temperature above the softening point of the polymer. For this,
the
material is usually heated to a temperature above the softening point and
introduced,
preferably continuously, into the mixing apparatus. The required amount of
aqueous
dispersion medium is similarly, preferably continuously, introduced into the
mixing
apparatus. The amount of dispersion medium selected here is generally such as
to set
the desired solids content of the dispersion. However, it is also possible to
use a larger
amount of the dispersion medium and then to concentrate the resultant
dispersion. It is
equally possible to begin by producing a more concentrated dispersion and to
dilute
this with further dispersion medium and/or water. The mass ratio of polymer
introduced
to the total amount of aqueous dispersion medium is typically in the range
from 1:20 to
PF 70540 CA 02791220 2012-08-27
7
1.2:1, frequently in the range from 1:10 to 1:1.1, and in particular in the
range from 1:3
to 1:1. In the case of continuous addition of polymer and of aqueous
dispersion
medium, the mass ratio of the streams of materials introduced is within the
abovementioned ranges. In the case of multistage addition of dispersion
medium, the
mass ratio of polymer introduced to the total amount of aqueous dispersion
medium
introduced in the first to penultimate stage can also be up to 4:1 or up to
2.3:1. It is
preferable that the introduction of polymer and of aqueous dispersion medium
takes
place at a constant addition rate, i.e. that the mass ratio of thermoplastic
polymer and
dispersion medium is constant during the process, or does not deviate by more
than
10% from the preselected mass ratio.
The introduction of the thermoplastic polymer into the aqueous dispersion
medium
typically takes place at a temperature which is at least 5 K, frequently at
least 10 K, and
in particular at least 20 K, e.g. within the range from 5 to 150 K, frequently
in the range
from 10 to 100 K, and in particular in the range from 20 to 80 K, above the
melting or
softening point of the polymer. This temperature is also termed mixing
temperature
hereinafter. The introduction of the polymer into the aqueous dispersion
medium
generally takes place at a temperature of at most 300 C, e.g. in the range
from 50 to
300 C, frequently from 60 to 250 C, and in particular from 100 to 200 C.
By virtue of the comparatively high mixing temperature, the introduction of
the melt into
the aqueous dispersion medium usually takes place at a pressure above
atmospheric
pressure, and generally at a pressure in the range from 1 to 50 bar,
frequently from 1.1
to 40 bar, in particular in the range from 1.5 to 20 bar.
The mixing process can be carried out in one or more stages, e.g. 2, 3, 4, or
5, where
at least one stage is carried out in a rotor-stator mixer. In the case of a
multistage
process, it is preferable that all of the stages are carried out in rotor-
stator mixers.
In one first embodiment of the invention, the mixing takes place in one stage,
i.e. the
mixing apparatus comprises a rotor-stator mixer. In this process, the amounts
of
polymer and dispersion medium required to produce the dispersion are generally
introduced into the rotor-stator mixer. A method that has proven successful
for this
heats the dispersion medium, prior to introduction, to the desired mixing
temperature or
a temperature of at least 20 K below the mixing temperature, and preferably to
a
temperature in the range mixing temperature +/- 20 K.
In a second, preferred embodiment of the invention, the mixing takes place in
a
plurality of stages, i.e. in a mixing apparatus which has a plurality of, e.g.
2, 3, 4, or 5,
in particular 3 or 4, rotor-stator mixers connected to one another in series.
In a method
which has proven successful here, the thermoplastic polymer and a portion of
the
dispersion medium are added to the first stage, i.e. to the first rotor-stator
mixer, where
PF 70540 CA 02791220 2012-08-27
8
they are mixed at a temperature above the melting or softening point of the
polymer,
using the portion of the aqueous dispersion medium. The portion of the
dispersion
medium added to the first stage here is usually from 10 to 60% by weight, in
particular
from 15 to 40% by weight, based on the total amount of the dispersion medium
introduced into the mixing apparatus. The introduction of the thermoplastic
polymer into
the portion of the aqueous dispersion medium typically takes place here at a
temperature which is at least 5 K, frequently at least 10 K, and in particular
at least
20 K, e.g. in the range from 5 to 150 K, frequently in the range from 10 to
100 K, and in
particular in the range from 20 to 80 K, above the melting or softening point
of the
polymer. The mixing temperature in the first rotor-stator mixer is generally
at most
300 C, being by way of example in the range from 50 to 300 C, frequently from
80 to
250 C, and in particular from 100 to 200 C. In a method which has proven
successful
for this, the portion of dispersion medium introduced into the first rotor-
stator mixer is
heated, prior to introduction, to the desired mixing temperature or to a
temperature
which is at least 20 K below the mixing temperature, preferably to a
temperature in the
range mixing temperature +/- 20 K. The aqueous dispersion produced in the
first rotor-
stator mixer is then transferred to a further rotor-stator mixer, where it is
mixed with a
further portion, or with the remaining portion, of the dispersion medium.
There can be,
for example, 1 or 2 further rotor-stator mixers following the second rotor-
stator mixer,
and the dispersion produced in the second rotor-stator mixer is mixed in the
optional
further rotor-stator mixer(s), e.g. in the third rotor-stator mixer, with the
remaining
amount, or with a further portion, of the aqueous dispersion medium. The
temperature
at which the dispersion produced in the first rotor-stator mixer is mixed with
further
dispersion medium in the second rotor-stator mixer can be the same as the
temperature in the first rotor-stator mixer, or higher or lower. It is
preferably below the
temperature in the first rotor-stator mixer. In a method which has proven
particularly
successful, the mixing temperature in the first of the rotor-stator mixers
connected to
one another in series is at least 20 K, preferably at least 30 K, e.g. from 20
to 200 K, in
particular from 30 to 120 K, above the temperature in the last of the rotor-
stator mixers
connected to one another in series. In particular, the temperature in the last
of the
rotor-stator mixers connected to one another in series is at least 5 K, in
particular at
least 10 K, e.g. from 5 to 200 K, in particular from 10 to 150 K, below the
melting or
softening point of the thermoplastic polymer.
In one preferred embodiment of the invention, the thermoplastic polymer and
the
aqueous dispersion medium which comprises the at least one surfactant
substance are
simultaneously introduced, preferably continuously, and in particular at a
constant rate
by volume, into the rotor-stator mixer(s), and the dispersion is removed in
similar
fashion.
However, it is also possible, in a preceding step, to mix the thermoplastic
polymer with
the aqueous dispersion medium which comprises the at least one surfactant
PF 70540 CA 02791220 2012-08-27
9
substance, thus obtaining a primary emulsion, at a temperature above the
melting or
softening point of the polymer, and to introduce this mixture to the rotor-
stator mixer.
Said preceding step is preferably carried out in a kneader or extruder. The
resultant
pre-emulsion is then introduced into the rotor-stator mixer(s). It is
preferable that the
pre-emulsion is kept at a temperature above the melting or softening point of
the
polymer.
The aqueous emulsion which is initially obtained and which is produced in the
mixing
apparatus, and which comprises the polymer in the aqueous dispersion medium,
is
then, i.e. after discharge from the mixing apparatus, quenched, i.e. rapidly
cooled to a
temperature below the softening point of the polymer, in order to avoid
agglomeration
of the polymer particles in the emulsion. The quenching process can be
undertaken in
a manner which is conventional per se, for example by using suitable cooling
apparatuses and/or via dilution with cooled dispersion medium. The residence
time of
the emulsion at temperatures above the melting or softening point of the
polymer, after
discharge from the mixing apparatus, should preferably be no longer than 20 s,
in
particular no longer than 10 s. In the case of a mixing apparatus which has a
plurality of
rotor-stator mixers connected to one another in series, the quenching process
can also
take place in the 2nd and the optional further rotor-stator mixers.
In the invention, the aqueous dispersion medium comprises, alongside water, at
least
one surfactant substance. Among these are polymeric surfactant substances with
molecular weights above 2000 daltons (number average), e.g. from 2200 to
106 daltons, these generally being termed protective colloids, and low-
molecular-weight
surfactant substances with molecular weights up to 2000 daltons, frequently up
to
1500 daltons (number average), these generally being termed emulsifiers. The
surfactant substances can be cationic, anionic, or neutral.
In one preferred embodiment of the invention, the aqueous dispersion medium
comprises at least one protective colloid, for example a neutral, anionic, or
cationic
protective colloid, optionally in combination with one or more emulsifiers.
Examples of protective colloids are water-soluble polymers, e.g.
- neutral protective colloids: e.g. polysaccharides, for example water-soluble
starches, starch derivatives, and cellulose derivatives, such as
methylcellulose,
hydroxypropylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose,
and
also polyvinyl alcohols, inclusive of partially hydrolyzed polyvinyl acetate
with a
degree of hydrolysis which is preferably at least 40%, in particular at least
60%,
polyacrylamide, polyvinylpyrrolidone, polyethylene glycols, graft polymers of
vinyl
acetate and/or vinyl propionate onto polyethylene glycols, and polyethylene
glycols mono- or bilaterally end-group-capped with alkyl, carboxy, or amino
groups;
PF 70540 CA 02791220 2012-08-27
- anionic water-soluble polymers, the main polymer chain of which has a
plurality
of carboxy groups, sulfonic acid groups, sulfonate groups, and/or phosphonic
acid groups or phosphonate groups, e.g. carboxymethylcellulose, homo- and
copolymers of ethylenically unsaturated monomers which comprise at least 20%
5 by weight, based on the total amount of the monomers, of at least one
ethylenically unsaturated monomer which comprises at least one carboxy group,
sulfonic acid group, and/or phosphonic acid group incorporated within the
polymer, and salts of these, in particular the alkali metal salts and ammonium
salts. When the abovementioned anionic water-soluble polymers are in an
10 aqueous medium, the sulfonic acid groups bonded to the main polymer chain
are
generally in the salt form, i.e. in the form of sulfonate groups, the
phosphonic acid
groups correspondingly being in the form of phosphonate groups. The
counterions are then typically alkali metal ions and alkaline earth metal
ions,
examples being sodium ions, and calcium ions, and ammonium ions (NH4);
- cationic polymers, e.g. polydiallyldimethylammonium salts, e.g. the
chlorides;
- anionically or cationically modified starches; examples of anionically
modified
starches are carboxymethylated starches and n-octenylsuccinyl-modified starch,
examples of these being obtainable in the form of products from Cargill
(CEmCap/CEmTex/CDeliTex n-octenylsuccinylated starches); examples of
cationically modified starches are starches modified with 2-hydroxy-3-
(trimethylammonium)propyl groups, examples being starches which are
obtainable by reacting conventional starches with N-(3-chloro-2-
hydroxypropyl)trimethylammonium chloride (CHPTAC), and which preferably
have a degree of substitution of from 0.02 to 0.1. The products Hi-Cat 21370
from Roquette and Perlcore 134P from Lyckeby are examples of these.
Examples of the anionic water-soluble polymers of which the main chain has a
plurality
of carboxy groups, sulfonic acid groups or sulfonate groups, and/or phosphonic
acid
groups or phosphonate groups, are:
- homo- and copolymers of monoethylenically unsaturated monocarboxylic acids
having from 3 to 6 carbon atoms (hereinafter monoethylenically unsaturated
C3-C6 monocarboxylic acids), examples being acrylic acid and methacrylic acid,
and salts thereof, in particular the alkali metal salts and ammonium salts;
- copolymers of monoethylenically unsaturated C3-C6 monocarboxylic acids with
neutral monomers, e.g. vinylaromatics, such as styrene, C,-C,o-alkyl esters of
monoethylenically unsaturated C3-C6 monocarboxylic acids, and/or C4-C6
dicarboxylic acids, examples being methyl acrylate, methyl methacrylate, ethyl
acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl
acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate,
n-hexyl
acrylate, n-hexyl methacrylate, hydroxyethyl esters, and in particular
hydroxyethyl
and hydroxypropyl esters of the abovementioned monoethylenically unsaturated
C3-C6 monocarboxylic acids and/or C4-C6 dicarboxylic acids, examples being
PF 70540 CA 02791220 2012-08-27
11
hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and
hydroxypropyl methacrylate, and also vinyl esters of aliphatic carboxylic
acids,
examples being vinyl acetate and vinyl propionate;
- homo- and copolymers of monoethylenically unsaturated sulfonic acids, e.g.
vinylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic
acid, 2-acryloxyethanesulfonic acid, 2-acryloxypropanesulfonic acid, etc., and
also copolymers thereof with the abovementioned neutral monomers, and also
the salts of the abovementioned homo- and copolymers, in particular the alkali
metal salts and ammonium salts;
- homo- and copolymers of monoethylenically unsaturated phosphonic acids, e.g.
vinylphosphonic acid, 2-acrylamido-2-methylpropanephosphonic acid, 2-
acryloxyethanephosphonic acid, 2-acryloxypropanephosphonic acid, etc., and
also copolymers thereof with the abovementioned neutral monomers, and also
the salts of the abovementioned homo- and copolymers, in particular the alkali
metal salts and ammonium salts;
where the proportion of the neutral comonomers in the abovementioned
copolymers
generally will not exceed a proportion of 80% by weight, in particular 70% by
weight,
based on the total amount of the monomers constituting the copolymer.
Particular anionic water-soluble polymers, the main chain of which has a
plurality of
sulfonate groups, are also
water-soluble copolyesters which have an amount of from 0.3 to 1.5 mmol/g of
polyester, in particular from 0.5 to 1.0 mmol/g of polyester, of aromatically
bonded sulfonic acid groups and, respectively, sulfonate groups, and salts of
these, in particular the alkali metal salts and ammonium salts thereof, where
the
water-soluble copolyesters are preferably composed of:
i) from 6 to 30 mol%, based on the total amount of components i), ii), and
iii),
of at least one aromatic dicarboxylic acid which has at least one sulfonate
group and which is preferably selected from 5-sulfoisophthalic acid or from
salts thereof, in particular the sodium salt of sulfoisophthalic acid, or
ester-
forming derivatives thereof;
ii) optionally one or more aromatic dicarboxylic acids which have no sulfonyl
groups and which are preferably selected from terephthalic acid and
isophthalic acid and mixtures thereof, or ester-forming derivatives thereof;
iii) optionally one or more aliphatic or cycloaliphatic dicarboxylic acids, or
ester-forming derivatives thereof;
iv) from 95 to 105 mol%, based on the total amount of components i), ii), and
iii), of one or more aliphatic diols, e.g. ethylene glycol, 1,2-propanediol,
1,3-
propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,4-dimethyl-
2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-
propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-
PF 70540 CA 02791220 2012-08-27
12
hexanediol, in particular ethylene glycol, 1,3-propanediol, 1,4-butanediol or
2,2-dimethyl-1,3-propanediol (neopentyl glycol),
where the total amount of components ii) and iii) makes up from 70 to 94 mol%,
based on the total amount of components i), ii) and iii), where components i),
ii),
iii), and iv) generally make up at least 99% by weight of all of the ester-
forming
constituents of the polyester (based on the components comprised within the
polyester). Water-soluble copolyesters of this type are known by way of
example
from US 6,521,679, the disclosure of which is hereby in its entirety
incorporated
herein by way of reference.
Examples of familiar nonionic emulsifiers are C2-C3-alkoxylated, in particular
ethoxylated, mono-, di-, and trialkylphenols (degree of ethoxylation from 3 to
50, alkyl
radical: C4 to C12), and also C2-C3-alkoxylated, in particular ethoxylated,
fatty alcohols
(degree of ethoxylation from 3 to 80; alkyl radical: C8 to C36). Examples of
these are the
Lutensol A grades (C12 to C14 fatty alcohol ethoxylates, degree of
ethoxylation from 3
to 8), Lutensol AO grades (C13 to C15 oxo alcohol ethoxylates, degree of
ethoxylation
from 3 to 30), Lutensol AT grades (C16 to C18 fatty alcohol ethoxylates,
degree of
ethoxylation from 11 to 80), Lutensol ON grades (C10 oxo alcohol ethoxylates,
degree of ethoxylation from 3 to 11), and the Lutensol TO grades (C13 oxo
alcohol
ethoxylates, degree of ethoxylation from 3 to 20), from BASF SE.
Conventional anionic emulsifiers are the salts of amphiphilic substances which
have an
anionic functional group, such as a sulfonate, phosphonate, sulfate, or
phosphate
group. Examples of these are the salts, in particular the alkali metal salts
and
ammonium salts, of alkyl sulfates (alkyl radical: C8 to C12), the salts, in
particular the
alkali metal salts and ammonium salts, of amphiphilic compounds which have a
sulfated or phosphated oligo-C2-C3-alkylene oxide group, in particular a
sulfated or
phosphated oligoethylene oxide group, examples being the salts, in particular
the alkali
metal salts and ammonium salts, of sulfuric acid hemiesters of ethoxylated
alkanols
(degree of ethoxylation from 2 to 50, in particular from 4 to 30, alkyl
radical: C10 to C30,
in particular C12 to C15), the salts, in particular the alkali metal salts and
ammonium
salts, of sulfuric acid hemiesters of ethoxylated alkylphenols (degree of
ethoxylation
from 2 to 50, alkyl radical: C4 to C12), the salts, in particular the alkali
metal salts and
ammonium salts, of phosphoric acid hemiesters of ethoxylated alkanols (degree
of
ethoxylation from 2 to 50, in particular from 4 to 30, alkyl radical: C10 to
C3o, in particular
C12 to C18), the salts, in particular the alkali metal salts and ammonium
salts, of
phosphoric acid hemiesters of ethoxylated alkylphenols (degree of ethoxylation
from 2
to 50, alkyl radical: C4 to C12), the salts, in particular the alkali metal
salts and
ammonium salts, of alkylsulfonic acids (alkyl radical: C12 to C18), the salts,
in particular
the alkali metal salts and ammonium salts, of alkylarylsulfonic acids (alkyl
radical: C9 to
C15), and also the salts, in particular the alkali metal salts and ammonium
salts, of
PF 70540 CA 02791220 2012-08-27
13
alkylbiphenyl ether sulfonic acids (alkyl radical: C6 to C18), an example
being the
product marketed as Dowfax 2A1.
Suitable cationic emulsifiers are generally cationic salts having a C6-C18-
alkyl, Ci-C,o-
alkylaryl, or heterocyclic radical, examples being primary, secondary,
tertiary, and
quaternary ammonium salts, alkanolammonium salts, pyridinium salts,
imidazolinium
salts, oxazolinium salts, morpholinium salts, thiazolinium salts, and also
salts of amine
oxides, quinolinium salts, isoquinolinium salts, tropylium salts, sulfonium
salts, and
phosphonium salts, in particular the appropriate sulfates, methosulfates,
acetates,
chlorides, bromides, phosphates, and hexafluorophosphates, and the like.
Examples
that may be mentioned are dodecylammonium acetate or the corresponding
sulfate,
the sulfates or acetates of the various paraffinic esters which involve the 2-
(N,N,N-
trimethylammonium)ethyl radical, N-cetylpyridinium sulfate, N-laurylpyridinium
sulfate,
and also N-cetyl-N,N,N-trimethylammonium sulfate, N-dodecyl-N,N,N-
trimethylammonium sulfate, N-octyl-N,N,N-trimethylammonium sulfate, N,N-
distearyl-
N, N-dimethylammonium sulfate, and also the Gemini surfactant N, N'-
(lauryldimethyl)-
ethylenediamine disulfate, ethoxylated tallow fatty alkyl-N-methylammonium
sulfate,
and ethoxylated oleylamine (for example Uniperol AC from BASF
Aktiengesellschaft,
about 12 ethylene oxide units).
In one preferred embodiment of the invention, the aqueous dispersion medium
comprises at least one neutral protective colloid, in particular one neutral,
protective
colloid bearing OH groups, optionally in combination with one or more
emulsifiers,
preferably anionic or nonionic emulsifiers, in particular anionic emulsifiers
which bear a
sulfate or sulfonate group. Examples of neutral protective colloids bearing OH
groups
are polysaccharides, e.g. water-soluble starches, starch derivatives, and
cellulose
derivatives, such as methylcellulose, hydroxypropylcellulose,
hydroxyethylcellulose,
hydroxypropylmethylcellulose, carboxymethylcellulose, and also polyvinyl
alcohols,
inclusive of partially hydrolyzed polyvinyl acetate having a degree of
hydrolysis which is
preferably at least 40%, in particular at least 60%. In particular, the
neutral protective
colloid bearing OH groups is selected from polyvinyl alcohols, inclusive of
partially
hydrolyzed polyvinyl acetates having a degree of hydrolysis which is
preferably at least
40%, in particular at least 60%.
In another preferred embodiment of the invention, the aqueous dispersion
medium
comprises at least one anionic protective colloid, optionally in combination
with one or
more nonionic protective colloids and/or one or more emulsifiers, preferably
one or
more nonionic and/or one anionic emulsifier(s). Suitable anionic protective
colloids are
the abovementioned anionic water-soluble polymers, the main polymer chain of
which
has a plurality of carboxy groups, sulfonic acid groups, or sulfonate groups,
and/or
phosphonic acid groups or phosphonate groups, and salts thereof, in particular
the
PF 70540 CA 02791220 2012-08-27
14
alkali metal salts and ammonium salts thereof. Among these, in particular
preference is
given to:
- homo- and copolymers of monoethylenically unsaturated C3-C6 monocarboxylic
acids, e.g. acrylic acid or methacrylic acid, and salts thereof, in particular
the
alkali metal salts and ammonium salts;
- salts, in particular alkali metal salts and ammonium salts, of copolymers of
monoethylenically unsaturated C3-C6 monocarboxylic acids with neutral
monomers, e.g. vinylaromatics, such as styrene, C,-C,o alkyl esters of
monoethylenically unsaturated C3-C6 monocarboxylic acids and/or C4-C6
dicarboxylic acids, e.g. methyl acrylate, methyl methacrylate, ethyl acrylate,
ethyl
methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl
methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate,
n-hexyl
methacrylate, hydroxyethyl esters, in particular hydroxyethyl and
hydroxypropyl
esters of the abovementioned monoethylenically unsaturated C3-C6
monocarboxylic acids and/or C4-C6 dicarboxylic acids, e.g. hydroxyethyl
acrylate,
hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl
methacrylate, and also vinyl esters of aliphatic carboxylic acids, e.g. vinyl
acetate
and vinyl propionate, where the proportion of the neutral comonomers in the
abovementioned comonomers will not generally exceed a proportion of 80% by
weight, in particular 70% by weight, based on the total amount of the monomers
constituting the copolymer, and also the salts of the abovementioned
copolymers,
in particular the alkali metal salts and ammonium salts;
- homo- and copolymers of monoethylenically unsaturated sulfonic acids, e.g.
vinylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic
acid, 2-acryloxyethanesulfonic acid, 2-acryloxypropanesulfonic acid, etc., and
also copolymers thereof with the abovementioned neutral monomers, and also
the salts of the abovementioned homo- and copolymers, in particular the alkali
metal salts and ammonium salts;
- anionically modified starches;
- water-soluble copolyesters which have an amount of from 0.3 to 1.5 mmol/g of
polyester, in particular from 0.5 to 1.0 mmol/g of polyester, of aromatically
bonded sulfonic acid groups and, respectively, sulfonate groups, and salts
thereof, in particular the alkali metal salts and ammonium salts thereof,
where the
water-soluble copolyesters are preferably composed of:
i) from 6 to 30 mol%, based on the total amount of components i), ii), and
iii),
of at least one aromatic dicarboxylic acid which has at least one sulfonate
group, and which is preferably selected from 5-sulfoisophthalic acid or from
salts thereof, in particular the sodium salt of sulfoisophthalic acid, or
ester-
forming derivatives thereof;
ii) optionally one or more aromatic dicarboxylic acid(s) which has/have no
sulfonyl groups, and which is/are preferably selected from terephthalic acid
PF 70540 CA 02791220 2012-08-27
and isophthalic acid and mixtures thereof, or ester-forming derivatives
thereof;
iii) optionally one or more aliphatic or cycloaliphatic dicarboxylic acids, or
ester-forming derivatives thereof;
5 iv) from 95 to 105 mol%, based on the total amount of components i), ii),
and
iii), of one or more aliphatic diols, e.g. ethylene glycol, 1,2-propanediol,
1,3-
propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,4-dimethyl-
2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-
propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-
10 hexanediol, in particular ethylene glycol, 1,3-propanediol, 1,4-butanediol
or
2,2-dimethyl-1,3-propanediol (neopentyl glycol),
where the total amount of components ii) and iii) makes up from 70 to 94 mol%,
based on the total amount of components i), ii) and iii), where components i),
ii),
iii), and iv) generally make up at least 99% by weight of all of the ester-
forming
15 constituents of the polyester (based on the components comprised within the
polyester). Water-soluble copolyesters of this type are known by way of
example
from US 6,521,679, the disclosure of which is hereby incorporated herein by
way
of reference.
Particularly preferred anionic protective colloids are those which have
sulfonic acid
groups and, respectively, sulfonate groups in the main polymer chain, in
particular the
abovementioned water-soluble copolyesters and salts thereof.
In a third, equally preferred, embodiment of the invention, the surfactant
substance
comprised within the aqueous dispersion medium comprises at least one anionic
emulsifier which comprises a sulfated or a phosphated oligo-C2-C3-alkylene
oxide
group, in particular a sulfated or a phosphated oligoethylene oxide group,
preferably in
the form of an alkali metal salt or ammonium salt. In said emulsifiers, the
oligo-C2-C3-
alkylene oxide group preferably has from 2 to 50, in particular from 4 to 30,
C2-C3-
alkylene oxide repeat units (number average) and it is preferable here that at
least 50%
of, and in particular all of, the C2-C3-alkylene oxide repeat units derive
from ethylene
oxide. Among these are by way of example the salts, in particular the alkali
metal salts
and ammonium salts of sulfuric acid hemiesters of ethoxylated alkanols (degree
of
ethoxylation from 2 to 50, in particular from 4 to 30, alkyl radical: C,o to
C30, in particular
C12 to C18), the salts, in particular the alkali metal salts and ammonium
salts, of sulfuric
acid hemiesters of ethoxylated alkylphenols (degree of ethoxylation from 2 to
50, alkyl
radical: C4 to C12), the salts, in particular the alkali metal salts and
ammonium salts, of
phosphoric acid hemiesters of ethoxylated alkanols (degree of ethoxylation
from 2 to
50, in particular from 4 to 30, alkyl radical: C10 to C30, in particular C12
to C18), the salts,
in particular the alkali metal salts and ammonium salts, of phosphoric acid
hemiesters
of ethoxylated alkylphenols (degree of ethoxylation from 2 to 50, alkyl
radical: C4 to
C12). Among these, particular preference is given to those emulsifiers which
have a
PF 70540 CA 02791220 2012-08-27
16
sulfated oligo-C2-C4-alkylene oxide group, and specifically a sulfated
oligoethylene
oxide group, preferably taking the form of an alkali metal salt or ammonium
salt.
Among these, particular preference is given to the salts, in particular the
alkali metal
salts and ammonium salts, of sulfuric acid hemiesters of ethoxylated alkanols,
where
these have a degree of ethoxylation of from 2 to 50, in particular from 4 to
30, and
where the alkyl radical underlying the alkanol is linear or branched and has
from 10 to
30, and in particular from 12 to 18, carbon atoms.
In said third, likewise preferred, embodiment of the invention, the surfactant
substance
comprised within the aqueous dispersion medium is preferably at least one
anionic
emulsifier which has a sulfated or a phosphated oligo-C2-C3-alkylene oxide
group, in
particular a sulfated or a phosphated oligoethylene oxide group,
or is a combination of at least one such anionic emulsifier with one or more
nonionic
emulsifiers,
or is a combination of at least one such anionic emulsifier with an anionic
emulsifier
that differs therefrom, optionally in combination with one or more nonionic
emulsifiers,
or is a combination of at least one such anionic emulsifier with one or more
nonionic
protective colloids, in particular with at least one of the protective
colloids that comprise
OH groups and that are stated to be preferred, and specifically with a
polyvinyl alcohol
or with a partially hydrolyzed polyvinyl acetate,
or is a combination of at least one such anionic emulsifier with one or more
of the
abovementioned anionic protective colloids, in particular those having
sulfonate groups
or having phosphonate groups.
In said third, likewise preferred, embodiment of the invention, the surfactant
substance
comprised within the aqueous dispersion medium is particularly preferably a
combination of at least one anionic emulsifier which has a sulfated or a
phosphated
oligo-C2-C3-alkylene oxide group, in particular a sulfated or a phosphated
oligoethylene
oxide group, with one or more nonionic protective colloids, in particular with
at least
one of the protective colloids which comprise OH groups and which are stated
to be
preferred, and specifically with a polyvinyl alcohol or with a partially
hydrolyzed
polyvinyl acetate.
The aqueous dispersion medium generally comprises a concentration of from 0.5
to
20% by weight of the surfactant substance, frequently a concentration of from
1 to 15%
by weight, in particular a concentration of from 1 to 10% by weight, based on
the
aqueous dispersion medium.
The aqueous dispersion medium can comprise, alongside water and the at least
one
surfactant substance, small amounts of further constituents, examples being
antifoams.
The proportion of constituents that differ from water and from surfactant
substance
PF 70540 CA 02791220 2012-08-27
17
does not generally exceed 5% by weight, in particular 1 % by weight, of the
aqueous
dispersion medium. It is preferable that the aqueous dispersion medium
comprises no,
or no significant amounts of, volatile organic solvents. in particular, the
content of
volatile organic solvents is less than 1% by weight, in particular less than
5000 ppm,
and specifically less than 1000 ppm. Volatile organic solvents are organic
solvents with
boiling point below 250 C at atmospheric pressure.
The process of the invention can in principle be applied to any of the
polymers which
have a plurality of ester groups in the main polymer chain. It has proven
particularly
successful for polymers which, when the methods of the prior art are used,
cannot be
converted to aqueous dispersions, or can be converted to aqueous dispersions
only by
using organic solvents or additives which reduce the viscosity of the
polymers.
These polymers are firstly defined via high zero-shear viscosity rlo, which at
180 C is
generally at least 60 Pa-s, frequently at least 80 Pa-s, in particular at
least 100 Pa-s,
e.g. from 60 to 20 000 Pa-s, in particular from 80 to 15 000 Pa-s,
specifically from 100
to 10 000 Pass, and via a low acid number: less than 5 mg KOH/g of polymer, in
particular at most 3 mg KOH/g of polymer, and specifically at most 1 mg KOH/g
of
polymer. The acid numbers stated here are the acid number to DIN EN 12634.
The polymers of the invention, moreover, naturally have in essence no
functional
groups which make the polymers water-soluble. Accordingly, the number of
sulfonic
acid groups in the polymer is generally less than 0.2 mmol/g, frequently less
than
0.1 mmol/g of polymer, in particular less than 0.05 mmol/g of polymer, or less
than
0.01 mmol/g of polymer. In one preferred embodiment of the invention, the
polymers
have from 0.01 to 0.2 mmol/g of sulfonic acid groups, in particular from 0.05
to
1.5 mmol/g. In another embodiment of the invention, the polymers have less
than
0.05 mmol/g of sulfonic acid groups, in particular less than 0.01 mmol/g.
The zero-shear viscosity rio at 180 C, also abbreviated hereinafter to rlo
(180 C), is the
limiting value of the dynamic viscosity of the polymer at a shear rate of 0
and at a
temperature of 180 C. This value can be determined to DIN 53019-2 from the
viscosity
curve obtained via dynamic viscosity measurements at 180 C at various shear
rates,
by extrapolating the viscosity curve to a shear rate of 0. By way of example,
viscosity
curves of this type can be determined by means of dynamic viscosity
measurement
with use of low-amplitude oscillatory shear at shear rates in the range from
0.01 to
500s-1.
The acid number can be determined in a manner known per se via titration of a
solution
of the polymer in a suitable solvent, such as tetrahydrofuran, pyridine, or
toluene, with
dilute ethanolic KOH solution (e.g. 0.1 N).
PF 70540 CA 02791220 2012-08-27
18
The number-average molecular weight MN of the polymers used in the process of
the
invention is typically in the range from 5000 to 1 000 000 daltons, in
particular in the
range from 8000 to 800 000 daltons, and specifically in the range from 10 000
to
500 000 daltons. The weight-average molecular weight Mw of the polymer is
generally
in the range from 20 000 to 5 000 000 daltons, frequently in the range from
30 000 daltons to 4 000 000 daltons, and in particular in the range from 40
000 to
2 500 000 daltons. The polydispersity index MW/MN is generally at least 2, and
is
frequently in the range from 3 to 20, in particular in the range from 5 to 15.
Molecular
weight and polydispersity index can by way of example be determined via gel
permeation chromatography (GPC) to DIN 55672-1.
The intrinsic viscosity of the polymers, which is an indirect measure of
molecular
weight, is typically in the range from 50 to 500 ml/g, frequently in the range
from 80 to
300 ml/g, and in particular in the range from 100 to 250 ml/g (determined to
EN ISO 1628-1 at 25 C on 0.5% strength by weight solution of the polymer in o-
dichlorobenzene/phenol (1:1 w/w)).
Examples of polymers which have a plurality of ester groups and/or carbonate
groups
in the main chain of the polymer are polyesters, polyesteramides,
polyetheresters,
polycarbonates, and polyester carbonates. The polymer used in the process of
the
invention is preferably selected from the group of the polyesters,
polyesteramides, and
polyetheresters, and mixtures thereof. The polymers are in particular a
polyester, a
mixture of various polyesters, or a mixture of at least one polyester with a
polymer from
the group of the polyesteramides and polyetheresters.
The polymers used in the process of the invention can be amorphous or
semicrysta I line.
In one embodiment of the invention, the polymer is a branched polymer, where
the
degree of branching preferably does not exceed a value of 1 mol/kg, in
particular
0.5 mol/kg, and specifically 0.3 mol/kg. The degree of branching is the number
of
monomer units condensed into the molecule which have more than 2, e.g. 3, 4,
5, or 6,
functional groups suitable for the condensation reaction, where these react
with
carboxylic acid groups or with hydroxy groups to form bonds, examples being
carboxylate, OH, isocyanate (NCO) or NH2 groups (or ester- or amide-forming
derivatives thereof). The degree of branching of the polymer in said
embodiment is
generally from 0.0005 to 1 mol/kg, preferably from 0.001 to 0.5 mol/kg, and in
particular
from 0.005 to 0.3 mol/kg. Surprisingly, polymers of this type have better
dispersion
characteristics than those which are unbranched, with a zero-shear viscosity
that is per
se identical.
PF 70540 CA 02791220 2012-08-27
19
In another embodiment of the invention, the polymer is in essence unbranched,
i.e. the
value of the degree of branching is generally < 0.005 mol/kg, in particular
< 0.001 mol/kg, and specifically < 0.0005 mol/kg.
In particular, the polymer is selected from the group of the aliphatic
polyesters, aliphatic
copolyesters, aliphatic-aromatic copolyesters, and mixtures of these.
An aliphatic polyester is a polyester composed exclusively of aliphatic
monomers. An
aliphatic copolyester is a polyester composed exclusively of at least two, in
particular at
least three, aliphatic monomers, where the acid component and/or the alcohol
component preferably comprises at least two monomers that differ from one
another.
An aliphatic-aromatic copolyester is a polyester which is composed of
aliphatic
monomers but also of aromatic monomers, and it is preferable here that the
acid
component comprises at least one aliphatic acid and at least one aromatic
acid.
The aliphatic polyesters and copolyesters are in particular polylactides,
polycaprolactone, block copolymers made of polylactide with poly-C2-C4-
alkylene
glycol, block copolymers made of polycaprolactone with poly-C2-C4-alkylene
glycol, and
also the copolyesters defined below which are composed of at least one
aliphatic or
cycloaliphatic dicarboxylic acid or an ester-forming derivative thereof, and
of at least
one aliphatic or cycloaliphatic diol component, and also optionally of further
components.
The term "polylactides" denotes polycondensates of lactic acid. Suitable
polylactides
are described in WO 97/41836, WO 96/18591, WO 94/05484, US 5,310,865,
US 5,428,126, US 5,440,008, US 5,142,023, US 5,247,058, US 5,247,059,
US 5,484,881, WO 98/09613, US 4,045,418, US 4,057,537, and also in Adv. Mater.
2000, 12, 1841-1846. These products are polymers based on lactide acid lactone
(A),
which is converted via ring-opening polymerization to polylactic acid polymers
(B):
O
H3C 10 TO O -Irk (B)
O O CiH3 CH3 n
The degree of polymerization n in formula (B) is in the range from 1000 to
4000,
preferably from 1500 to 3500, and particularly preferably from 1500 to 2000
(number
average). The average molar masses (number average) of these products are, in
accordance with the degree of polymerization, in the range from 71 000 to
284 000 g/mol. Suitable polylactides are obtainable by way of example from
Cargill
Dow LLC (e.g. PLA Polymer 4041D, PLA Polymer 4040D, PLA Polymer 4031 D, PLA
PF 70540 CA 02791220 2012-08-27
Polymer 2000D, or PLA Polymer 1100) from Mitsui Chemicals (Lactea). Other
suitable
materials are diblock and triblock copolymers of polylactides with poly-C2-C4-
alkylene
glycol, in particular with poly(ethylene glycol). These block copolymers are
marketed by
way of example by Aldrich (e.g. product number 659649). These are polymers
that
5 have polylactide blocks and poly-C2-C4-alkylene oxide blocks. These block
copolymers
are obtainable by way of example via condensation of lactic acid or via ring-
opening
polymerization as lactide (A) in the presence of poly-C2-C4-alkylene glycols.
Other polymers suitable in the invention are polycaprolactones. The person
skilled in
10 the art understands these to be polymers described by the formula D
indicated below,
where n is the number of repeat units in the polymer, i.e. the degree of
polymerization.
O O O
* + 0 ~'~~n *
(C) (D)
15 The degree of polymerization n in formula (D) is in the range from 100 to
1000,
preferably from 500 to 1000 (number average). The number-average molar masses
of
these products are, in accordance with the degree of polymerization, in the
range from
10 000 g/mol to 100 000 g/mol. Particularly preferred polymers of the formula
(D) have
average molar masses (number average) of 50 000 g/mol (CAPA 6500), 80 000
g/mol
20 (CAPA 6800), and 100 000 g/mol (CAPA FB 100). Polycaprolactones are
generally
produced via ring-opening polymerization of E-caprolactone (compound C) in the
presence of a catalyst. Polycaprolactones are obtainable commercially from
Solvay as
CAPA polymers, e.g. CAPA 6100, 6250, 6500 or CAPA FB 100. Other suitable
polymers are diblock and triblock copolymers of polycaprolactone with poly-C2-
C4-
alkylene glycols, in particular with polyethylene glycols (= polyethylene
oxides), i.e.
polymers which have at least one polycaprolactone block of the formula D and
at least
one polyalkylene glycol block. These polymers can by way of example be
produced via
polymerization of caprolactone in the presence of polyalkylene glycols, for
example by
analogy with the processes described in Macromolecules 2003, 36, pp 8825-8829.
Particular polymers that are suitable in the invention are copolyesters, where
these are
composed of at least one aliphatic or cycloaliphatic dicarboxylic acid or of
an ester-
forming derivative thereof, and of at least one aliphatic or cycloaliphatic
diol
component, and also optionally of further components.
In particular, the polymer to be dispersed in the invention is an aliphatic or
aliphatic-
aromatic copolyester which is in essence composed of:
a) at least one dicarboxylic acid component A, which is composed of
PF 70540 CA 02791220 2012-08-27
21
al) at least one aliphatic or cycloaliphatic dicarboxylic acid or ester-
forming
derivatives thereof, or a mixture thereof, and
a2) optionally one or more aromatic dicarboxylic acids or ester-forming
derivatives thereof, or a mixture thereof;
b) at least one diol component B, selected from aliphatic and cycloaliphatic
diols and
mixtures thereof;
c) optionally one or more further bifunctional compounds C which react with
carboxylic acid groups or with hydroxy groups to form bonds; and
d) optionally one or more compounds D which have at least 3 functionalities
which
react with carboxylic acid groups or with hydroxy groups to form bonds;
where either the compounds al), a2), B), C), and D) have no sulfonic acid
group,
or the compounds of groups al), a2), B), C), and D) comprise, based on the
total
amount of compounds of component A, up to 3 mol% of a compound which has one
or
more sulfonic acid groups, e.g. from 0.1 to 3 mol% or from 0.1 to 2 mol% or
from 0.2 to
1.5 mol%,
where the molar ratio of component A to component B is in the range from 0.4:1
to 1:1,
in particular in the range from 0.6:1 to 0.99:1, and components A and B make
up at
least 80% by weight, in particular at least 90% by weight, and specifically at
least 96%
by weight, of all of the ester-forming constituents of the polyester and,
respectively, of
the total weight of the polyester.
Here and hereinafter, the % by weight data referring to the ester-forming
constituents
are based on the constituents of components A, B, C, and D in the form
condensed
into the molecule, and are thus based on the total mass of the polyester, and
not on the
amounts used to produce the polyester, unless otherwise stated.
The acid component A in said copolyesters preferably comprises
al) from 30 to 100 mol%, in particular from 35 to 90 mol%, or from 40 to 90
mol%, of
at least one aliphatic or at least one cycloaliphatic dicarboxylic acid, or
ester-
forming derivatives thereof, or a mixture thereof,
a2) from 0 to 70 mol%, in particular from 10 to 65 mol%, or from 10 to 60
mol%, of at
least one aromatic dicarboxylic acid, or ester-forming derivative thereof, or
a
mixture thereof,
where the total of the molar percentages of components al) and a2) is 100%.
In one specific embodiment of the invention, acid component A comprises
al) from 35 to 90 mol%, or from 40 to 90 mol%, and specifically from 60 to 90
mol%,
of at least one aliphatic or at least one cycloaliphatic dicarboxylic acid, or
ester-
forming derivatives thereof, or a mixture thereof,
PF 70540 CA 02791220 2012-08-27
22
a2) from 10 to 65 mol%, or from 10 to 60 mol%, and specifically from 10 to 40
mol%,
of at least one aromatic dicarboxylic acid, or ester-forming derivative
thereof, or a
mixture thereof,
where the total of the molar percentages of components a1) and a2) is 100%.
The acid component A can also comprise, condensed into the molecule, small
amounts
of a sulfonated carboxylic acid, in particular of a sulfonated aromatic
dicarboxylic acid,
e.g. sulfoisophthalic acid, or a salt thereof, where the proportion of the
sulfonated
carboxylic acid generally is not more than 3 mol%, being by way of example in
the
range from 0.1 to 3 mol%, or from 0.1 to 2 mol%, or from 0.2 to 1.5 mol%,
based on the
total amount of compounds of component A. In one embodiment of the invention,
the
amount of sulfonated carboxylic acid is less than 1 mol%, in particular less
than
0.5 mol%, based on component A.
In one preferred embodiment of the invention, copolyesters of this type have
from 0.01
to 0.2 mmol/g of sulfonic acid groups, in particular from 0.05 to 1.5 mmol/g.
In another
embodiment of the invention, copolyesters of this type have less than 0.05
mmol/g of
sulfonic acid groups, in particular less than 0.01 mmol/g.
Aliphatic dicarboxylic acids al) which are suitable in the invention generally
have from
2 to 10 carbon atoms, preferably from 4 to 8 carbon atoms, and in particular 6
carbon
atoms. They can be either linear or branched acids. The cycloaliphatic
dicarboxylic
acids that can be used for the purposes of the present invention are generally
those
having from 7 to 10 carbon atoms and in particular those having 8 carbon
atoms.
However, it is also possible in principle to use dicarboxylic acids having a
greater
number of carbon atoms, for example up to 30 carbon atoms. Examples that may
be
mentioned are: malonic acid, succinic acid, glutaric acid, 2-methylglutaric
acid, 3-
methylglutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid,
fumaric acid,
2,2-dimethylglutaric acid, suberic acid, 1,3-cyclopentanedicarboxylic acid,
1,4-
cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, diglycolic
acid,
itaconic acid, maleic acid, and 2,5-norbornanedicarboxylic acid. Ester-forming
derivatives of the abovementioned aliphatic or cycloaliphatic dicarboxylic
acids which
can equally be used and which may be mentioned are in particular the di-C,-C6-
alkyl
esters, e.g. dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl,
diisobutyl, di-t-butyl, di-
n-pentyl, diisopentyl, or di-n-hexyl ester. It is equally possible to use
anhydrides of the
dicarboxylic acids. Preferred dicarboxylic acids are succinic acid, adipic
acid, sebacic
acid, azelaic acid, and brassylic acid, and also the respective ester-forming
derivatives
thereof, or a mixture thereof. Particular preference is given to adipic acid,
sebacic acid,
or succinic acid, and also to the respective ester-forming derivatives
thereof, or a
mixture thereof.
PF 70540 CA 02791220 2012-08-27
23
Aromatic dicarboxylic acids a2 that may be mentioned are generally those
having from
8 to 12 carbon atoms and preferably those having 8 carbon atoms. Examples that
may
be mentioned are terephthalic acid, isophthalic acid, 2,6-naphthoic acid, and
1,5-
naphthoic acid, and also ester-forming derivatives thereof. Particular mention
may be
made here of the di-C,-C6-alkyl esters, e.g. dimethyl, diethyl, diethyl, di-n-
propyl,
diisopropyl, di-n-butyl, diisobutyl, di-t-butyl, di-n-pentyl, diisopentyl, or
di-n-hexyl ester.
The anhydrides of the dicarboxylic acids a2 are equally suitable ester-forming
derivatives. However, it is also in principle possible to use aromatic
dicarboxylic acids
a2 having a greater number of carbon atoms, for example up to 20 carbon atoms.
The
aromatic dicarboxylic acids or ester-forming derivatives thereof a2 can be
used
individually or in the form of mixture made of two or more thereof. It is
particularly
preferable to use terephthalic acid or ester-forming derivatives thereof, e.g.
dimethyl
terephthalate.
Among the aromatic dicarboxylic acids and ester-forming derivatives thereof
are
especially those which have no sulfonic acid groups. Here and hereinafter
these are
also termed aromatic dicarboxylic acids a2.1. Among the aromatic sulfonic
acids are
also sulfonated aromatic dicarboxylic acids and ester-forming derivatives
thereof
(aromatic dicarboxylic acids a.2.2). These typically derive from the
abovementioned
aromatic dicarboxylic acids and bear 1 or 2 sulfonic acid groups. An example
that may
be mentioned is sulfoisophthalic acid or a salt thereof, e.g. the sodium salt
(Nasip). The
content of the sulfonated carboxylic acid generally makes up no more than 3
mol%,
based on component A, and by way of example is in the range from 0.1 to 3
mol%, or
from 0.1 to 2 mol%, or from 0.2 to 1.5 mol%, based on the total amount of
compounds
of component A. In one embodiment of the invention, the amount of sulfonated
carboxylic acids, based on component A, is less than 1 mol%, in particular
less than
0.5 mol%.
The diols B are generally selected from branched or linear alkanediols having
from 2 to
12 carbon atoms, preferably from 4 to 8 carbon atoms, or in particular 6
carbon atoms,
or from cycloalkanediols having from 5 to 10 carbon atoms.
Examples of suitable alkanediols are ethylene glycol, 1,2-propanediol, 1,3-
propanediol,
1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,4-dimethyl-2-ethylhexane-
1,3-diol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-
isobutyl-1,3-
propanediol, 2,2,4-trimethyl-1,6-hexanediol, in particular ethylene glycol,
1,3-
propanediol, 1,4-butanediol or 2,2-dimethyl-1,3-propanediol (neopentyl
glycol);
cyclopentanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-
cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-
cyclobutanediol. It is also possible to use mixtures of various alkanediols.
Diol
component B in said copolyesters is preferably selected from C2-C12
alkanediols and
PF 70540 CA 02791220 2012-08-27
24
mixtures thereof. Preference is given to 1,3-propanediol and in particular to
1,4-butanediol.
Depending on whether an excess of OH end groups is desired, an excess of
component B can be used. In one preferred embodiment, the molar ratio of
components used A:B can be in the range from 0.4:1 to 1.1:1, preferably in the
range
from 0.6:1 to 1.05:1, and in particular in the range from 0.7:1 to 1.02:1. The
molar ratio
of component A incorporated into the polymer to component B incorporated into
the
polymer is preferably in the range from 0.8:1 to 1.01:1, with preference from
0.9:1 to
1:1, and in particular in the range from 0.99:1 to 1:1.
The polyesters can comprise, condensed into the molecule, not only components
A
and B but also further bifunctional components C. Said bifunctional compounds
have
two functional groups which react with carboxylic acid groups or preferably
hydroxy
groups, to form bonds. Examples of functional groups which react with OH
groups are
in particular isocyanate groups, epoxy groups, oxazoline groups, carboxy
groups in
free or esterified form, and amide groups. Particular functional groups which
react with
carboxy groups are hydroxy groups and primary amino groups. These materials
are
particularly those known as bifunctional chain extenders, in particular the
compounds
of groups c3) to c7). Among components C are:
c1) dihydroxy compounds of the formula I
HO-[(A)-O]m-H (I)
in which A is a C2-C4-alkylene unit, such as 1,2-ethanediyl, 1,2-propanediyl,
1,3-propanediyl, or 1,4-butanediyl, and m is an integer from 2 to 250;
c2) hydroxycarboxylic acids of the formula Ila or Ilb
HO+C(O)-G-O- -H C(O-)-G-O
r
(Ila) (lib)
in which p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G
is a
radical selected from the group consisting of phenylene, -(CH2)q-, where q is
an
integer from 1 to 5, -C(R)H-, and -C(R)HCH2, where R is methyl or ethyl;
c3) amino-C2-C12 alkanols, amino-C5-C,o cycloalkanols, or a mixture thereof;
PF 70540 CA 02791220 2012-08-27
c4) diamino-C,-C8 alkanes;
c5) 2,2'-bisoxazolines of the general formula III
FN R~N
0 0
5 (III)
where R, is a single bond, a (CH2)7-alkylene group, where z = 2, 3, or 4, or a
phenylene group;
10 c6) aminocarboxylic acids which by way of example are selected from
naturally
occurring amino acids, polyamides with a molar mass of at most 18 000 g/mol,
obtainable via polycondensation of a dicarboxylic acid having from 4 to 6
carbon
atoms and of a diamine having from 4 to 10 carbon atoms, compounds of the
formulae IVa and lVb
HO+C(O)-T-N(H) H
S C(O)-T-N(H) t
(IVa) (lVb)
in which s is an integer from 1 to 1500 and t is an integer from 1 to 4, and T
is a
radical selected from the group consisting of phenylene, -(CH2),-, where u is
an
integer from 1 to 12, -C(R2)H-, and -C(R2)HCH2, where R2 is methyl or ethyl,
and polyoxazolines having the repeat unit V
N- CHI-CI-12t
O R3
(V)
in which R3 is hydrogen, C,-C6-alkyl, C5-C8-cycloalkyl, unsubstituted phenyl
or
phenyl substituted up to three times with C,-C4-alkyl groups, or is
tetrahydrofuryl;
and
c7) diisocyanates.
PF 70540 CA 02791220 2012-08-27
26
Examples of component c1 are diethylene glycol, triethylene glycol,
polyethylene
glycol, polypropylene glycol, and polytetrahydrofuran (polyTHF), particularly
preferably
diethylene glycol, triethylene glycol, and polyethylene glycol, and it is also
possible
here to use mixtures thereof, or compounds which have different alkylene units
A (see
formula I), e.g. polyethylene glycol which comprises propylene units (A = 1,2-
or
1,3-propanediyl). The latter are obtainable by way of example via
polymerization of first
ethylene oxide and then propylene oxide, by methods known per se. Particular
preference is given to copolymers based on polyalkylene glycols having various
variables A, where units formed from ethylene oxide (A = 1,2-ethanediyl)
predominate.
The molar mass (number average Mn) of the polyethylene glycol is generally
selected
to be in the range from 250 to 8000 g/mol, preferably from 600 to 3000 g/mol.
In one of the embodiments it is possible by way of example to use, for the
production of
the copolyesters, from 80 to 99.8 mol%, preferably from 90 to 99.5 mol%, of
the diols
B, and from 0.2 to 20 mol%, preferably from 0.5 to 10 mol%, of the dihydroxy
compounds c1, based on the molar amount of B and c1.
Examples of preferred components c2 are glycolic acid, D-, L-, or D,L-lactic
acid,
6-hydroxyhexanoic acid, cyclic derivatives thereof, e.g. glycolide (1,4-
dioxane-2,5-
dione), D- or L-dilactide (3,6-dimethyl-1,4-dioxane-2,5-dione), p-
hydroxybenzoic acid,
and also oligomers thereof, and polymers, such as 3-polyhydroxybutyric acid,
polyhydroxyvaleric acid, polylactide (obtainable by way of example in the form
of
EcoPLA (Cargill)), or else a mixture of 3-polyhydroxybutyric acid and
polyhydroxyvaleric acid (the latter being obtainable as Biopol from Zeneca).
The low-
molecular-weight and cyclic derivatives thereof are particularly preferred for
producing
copolyesters. Examples of amounts that can be used of the hydroxycarboxylic
acids or
their oligomers and/or polymers are from 0.01 to 20% by weight, preferably
from 0.1 to
10% by weight, based on the amount of A and B.
Preferred components c3 are amino-C2-C6 alkanols, such as 2-aminoethanol,
3-aminopropanol, 4-aminobutanol, 5-aminopentanol, 6-aminohexanol, and also
amino-
C5-C6 cycloalkanols, such as aminocyclopentanol and aminocyclohexanol, or a
mixture
thereof.
Preferred components c4) are diamino-C4-C6 alkanes, such as 1,4-diaminobutane,
1,5-diaminopentane, and 1,6-diaminohexane.
In one preferred embodiment, the amounts used for producing the copolyesters
are
from 0.5 to 20 mol%, preferably from 0.5 to 10 mol%, of c3, based on the molar
amount
of B, and from 0 to 15 mol%, preferably from 0 to 10 mol%, of c4, based on the
molar
amount of B.
PF 70540 CA 02791220 2012-08-27
27
Preferred bisoxazolines III of component c5) are those in which R' is a single
bond, a
(CH2)Z-alkylene group, where z = 2, 3, or 4, e.g. methylene, ethane-l,2-diyl,
propane-
1,3-diyl, propane-l,2-diyl, or a phenylene group. Particularly preferred
bisoxazolines
that may be mentioned are 2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-
bis(2-
oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, or 1,4-bis(2-oxazolinyl)
butane, 1,4-
bis(2-oxazolinyl) benzene, 1,2-bis(2-oxazolinyl) benzene, or 1,3-bis(2-
oxazolinyl)benzene. Bisoxazolines of the general formula III are generally
obtainable
via the process of Angew. Chem. Int. Edit., Vol. 11 (1972), pp. 287-288.
Examples of amounts that can be used for producing the polyesters are from 80
to
98 mol% of B, up to 20 mol% of c3, e.g. from 0.5 to 20 mol% of c3, up to 20
mol% of
c4, e.g. from 0.5 to 20 mol%, and up to 20 mol% of c5, e.g. from 0.5 to 20
mol%, based
in each case on the total of the molar amounts of components B, c3, c4, and
c5. In
another preferred embodiment it is possible to use from 0.1 to 5% by weight of
c5,
preferably from 0.2 to 4% by weight, based on the total weight of A and B.
Component c6 used can comprise naturally occurring aminocarboxylic acids.
Among
these are valine, leucine, isoleucine, threonine, methionine, phenylalanine,
tryptophan,
lysine, alanine, arginine, aspartamic acid, cysteine, glutamic acid, glycine,
histidine,
proline, serine, tryosine, asparagine, and glutamine.
Preferred aminocarboxylic acids of the general formulae IVa and lVb are those
in which
s is an integer from 1 to 1000 and t is an integer from I to 4, preferably 1
or 2, and T is
selected from the group of phenylene and -(CH2)u-, where u is 1, 5, or 12.
c6 can also moreover be a polyoxazoline of the general formula V. However,
component c6 can also be a mixture of various aminocarboxylic acids and/or
polyoxazolines.
Amounts of c6 that can be used in one preferred embodiment are from 0.01 to
20% by
weight, preferably from 0.1 to 10% by weight, based on the total amount of
components A and B.
Component c7 used can comprise aromatic or aliphatic diisocyanates. However,
it is
also possible to use isocyanates of higher functionality. Examples of aromatic
diisocyanates are tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate,
diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate,
diphenylmethane 4,4'-diisocyanate, naphthylene 1,5-diisocyanate, and xylylene
diisocyanate. Examples of aliphatic diisocyanates are especially linear or
branched
alkylene diisocyanates or cycloalkylene diisocyanates having from 2 to 20
carbon
atoms, preferably having from 3 to 12 carbon atoms, e.g. hexamethylene 1,6-
diisocyanate, isophorone diisocyanate, or methylenebis(4-
isocyanatocyclohexane).
PF 70540 CA 02791220 2012-08-27
28
Other components c7 that can be used are tri(4-isocyanatophenyl)methane, and
also
the cyanurates, uretdiones, and biurets of the abovementioned diisocyanates.
Amounts generally used of component c7, if desired, are from 0.01 to 5 mol%,
preferably from 0.05 to 4 mol%, particularly preferably from 0.1 to 4 mol%,
based on
the total of the molar amounts of A and B.
Among other components which can optionally be used for producing the
polyesters
are compounds D which comprise at least three groups/functionalities which
react with
carboxylic acid groups or with hydroxy groups, to form bonds. Particular
examples of
functional groups which react with OH groups are isocyanate groups, epoxy
groups,
oxazoline groups, carboxy groups in free or esterified form, and amide groups.
Particular functional groups which react with carboxy groups are hydroxy
groups and
primary amino groups. Compounds of this type are also termed crosslinking
agents. By
using the compound D, it is possible to construct biodegradable copolyesters
which are
pseudoplastic. The rheology of the melts improves; the biodegradable
copolyesters are
easier to process, for example easier to draw by melt-solidification processes
to give
foils. The compounds D have a shear-thinning effect, i.e. viscosity decreases
under
load. The compounds D preferably comprise from 3 to 10, e.g. 3, 4, 5, or 6,
functional
groups capable of forming ester bonds. Particularly preferred compounds D have
from
three to six functional groups of this type in the molecule, in particular
from three to six
hydroxy groups and/or carboxy groups. Examples that may be mentioned are:
polycarboxylic acids and hydroxycarboxylic acids, e.g. tartaric acid, citric
acid, malic
acid; trimesic acid; trimellitic acid, trimellitic anhydride; pyromellitic
acid, pyromellitic
dianhydride, and hydroxyisophthalic acid, and also polyols, such as
trimethylolpropane
and trimethylolethane; pentaerythritol, polyethertriols, and glycerol.
Preferred
compounds D are polyols, preferably trimethylolpropane, pentaerythritol, and
in
particular glycerol. The amounts used of the compounds D, insofar as these are
desired, are generally from 0.0005 to 1 mol/kg, preferably from 0.001 to 0.5
mol/kg,
and in particular from 0.005 to 0.3 mol/kg, based on total amount of
components A, B,
C, and D, or on the total weight of the polyester. The amounts used of the
compounds
D, insofar as these are desired, are preferably from 0.01 to 5% by weight, in
particular
from 0.05 to 3% by weight, and in particular from 0.1 to 2% by weight, and
specifically
from 0.2 to 2% by weight, based on the total amount of components A, B, C, and
D, or
on the total weight of the polyester.
It is generally advisable to add the crosslinking (at least trifunctional)
compounds D at a
relatively early juncture in the polycondensation reaction.
Production of the copolyesters preferred in the invention can also use,
alongside the
abovementioned components A, B, and optionally C, and optionally D, bi- or
polyfunctional epoxides (component E). Particularly suitable bi- or
polyfunctional
PF 705540 CA 02791220 2012-08-27
29
epoxides are copolymers which contain epoxy groups and which are based on
styrene,
acrylate, and/or methacrylate. The units bearing epoxy groups are preferably
glycidyl
(meth)acrylates. Copolymers which have proven successful are those having a
proportion of greater than 20% by weight, particularly preferably greater than
30% by
weight, and with particular preference greater than 50% by weight, of glycidyl
methacrylate, based on the copolymer. The epoxy equivalent weight (EEW) in
said
polymers is preferably from 150 to 3000 g/equivalent and with particular
preference
from 200 to 500 g/equivalent. The average molecular weight (weight average) Mw
of
the polymers is preferably from 2000 to 25 000, in particular from 3000 to
8000. The
average molecular weight (number average) M, of the polymers is preferably
from 400
to 6000, in particular from 1000 to 4000. Polydispersity (Q) is generally from
1.5 to 5.
Copolymers of the abovementioned type, containing epoxy groups, are marketed
by
way of example by BASF Resins B.V. with trademark Joncryl ADR. Joncryl ADR
4368 is particularly suitable as component E. Component E is usually used as
chain
extender. In relation to the amount, the information given above for component
E, and
in particular for components c2), c3), c4), c5), and c6), is applicable.
In particularly preferred copolyesters, acid component A in particular
comprises
al) from 60 to 90 mol%, or from 60 to 80 mol%, in particular from 65 to 80
mol%, and
specifically from 66 to 75 mol%, of at least one aliphatic or at least one
cycloaliphatic dicarboxylic acid, or ester-forming derivatives thereof, or a
mixture
thereof,
a2) from 10 to 40 mol%, or from 20 to 40 mol%, in particular from 20 to 35
mol%, and
specifically from 25 to 34 mol%, of at least one aromatic dicarboxylic acid,
or
ester-forming derivative thereof, or a mixture thereof, where the aromatic
dicarboxylic acid is preferably terephthalic acid, and
where the molar percentages of components a1) and a2) give a total of 100%.
Although particularly preferred copolyesters of this type have comparatively
high zero-
shear viscosity at 180 C, they feature comparatively good dispersibility.
Among the particularly preferred copolyesters, particular preference is given
to those in
which the polyester-forming constituents comprise, based on the total weight
of the
polyester, from 0.1 to 2% by weight, frequently from 0.2 to 2% by weight, in
particular
from 0.3 to 1.8% by weight, and specifically from 0.4 to 1.5% by weight, of
one or more
compounds D which have at least 3 functionalities suitable for forming ester
groups. In
relation to preferred compounds D, the information given above is applicable.
Among the particularly preferred copolyesters, particular preference is given
to those in
which the proportion of diol component B is from 98 to 102 mol%, based on the
total
amount of components al) and a2). In relation to preferred diols, the
information given
above is applicable.
PF 70540 CA 02791220 2012-08-27
Among the particularly preferred copolyesters, particular preference is given
to those in
which the polyester-forming constituents comprise, based on the total weight
of the
polyester, no more than 2% by weight of one or more further bifunctional
compounds C
which react with carboxylic acid groups or with hydroxy groups to form bonds.
In
5 relation to preferred compounds C, the information given above is
applicable.
Within the particularly preferred copolyesters, it is preferable that
components al), a2),
and b) make up from 96 to 99.8% by weight of the particularly preferred
copolyester.
10 The copolyesters are to some extent known, e.g. from EP-A 488 617, WO
96/15173,
and WO 04/67632, or can be produced by methods known per se. It is
particularly
preferable to produce the copolyesters by the continuous process described in
EP
Application No. 08154541Ø
15 In one first embodiment, the copolyesters described are synthesized in a
two-stage
reaction cascade. The general method begins by reacting the dicarboxylic acids
or their
derivatives A together with component B and optionally D in the presence of an
esterification catalyst (or if the carboxylic acids A are used in the form of
their esters, in
the presence of a transesterification catalyst) to give a prepolyester. The
intrinsic
20 viscosity (IV) of said prepolyester is generally from 50 to 100 mUg,
preferably from 60
to 90 mUg. The catalysts used generally comprise zinc catalysts, aluminum
catalysts,
and in particular titanium catalysts. An advantage of titanium catalysts, such
as
tetra(isopropyl) orthotitanate and in particular tetrabutyl orthotitanate
(TBOT), over the
tin catalysts, antimony catalysts, cobalt catalysts, and lead catalysts
frequently used in
25 the literature, an example being tin dioctanoate, is that if any residual
amounts of the
catalyst or of downstream products of the catalyst remain within the product,
they are
less toxic. This is a particularly important factor for the biodegradable
polyesters, since
they pass directly into the environment, by way of example in the form of
composting
bags or mulch films. The polyesters of the invention are then optionally chain-
extended
30 by the processes described in WO 96/15173 and EP-A 488 617. The
prepolyester is,
by way of example, reacted with chain extenders C), e.g. with diisocyanates,
or with
epoxy-containing polymethacrylates, in a chain-extension reaction to give a
polyester
with IV of from 60 to 450 mUg, preferably from 80 to 250 mUg.
In another method, component A is first condensed in the presence of an excess
of
component B and optionally D, together with the catalyst. The melt of the
resultant
prepolyester is then condensed, usually at an internal temperature of from 200
to
250 C, while diol liberated is removed by distillation, until the desired
viscosity has
been reached, the intrinsic viscosity (IV) being from 60 to 450 mUg, and
preferably
from 80 to 250 mUg. Said condensation reaction generally takes place within a
period
of from 3 to 6 hours at reduced pressure. A reaction with the chain extender
of
component D then optionally follows.
CA 02791220 2012-08-27
PF 70540
31
It is particularly preferable to produce the copolyesters by the continuous
process
described in EP Application No. 08154541Ø Here, by way of example, a mixture
made
of components A and B and optionally of further comonomers is mixed to give a
paste,
without addition of any catalyst, or as an alternative the liquid esters of
component A
and component B and optionally further comonomers are fed to the reactor,
without
addition of any catalyst, and
1. in a first stage, said mixture is continuously esterified or, respectively,
transesterified together with the entire amount or a portion of the catalyst;
2. in a second stage, optionally with the remaining amount of catalyst, the
transesterification or esterification product obtained in 1.) is continuously
precondensed preferably in a tower reactor, where the product stream is
conducted cocurrently by way of a falling-film cascade, and the reaction
vapors
are removed in situ from the reaction mixture - until an intrinsic viscosity
of
from 20 to 60 mUg to DIN 53728 has been reached;
3. in a third stage, the product obtainable from 2.) is continuously
polycondensed
- preferably in a cage reactor - until an intrinsic viscosity of from 70 to
130 mL/g to DIN 53728 has been reached and optionally
4. in a fourth stage, the product obtainable from 3.) is continuously reacted
in a
polyaddition reaction with a chain extender in an extruder, List reactor, or
static
mixer, until an intrinsic viscosity of from 80 to 250 mUg to DIN 53728 has
been
reached.
The abovementioned intrinsic viscosity ranges serve merely as guides to
preferred
process variants, and are not intended to have any restricting effect on the
subject
matter of the present application.
The copolyesters of the invention can be produced not only by the continuous
process
described above but also in a batch process. For this, components A, B, and
optionally
D are mixed in any desired feed sequence and condensed to give a prepolyester.
A
polyester with the desired intrinsic viscosity can be obtained with the
optional aid of
component D.
The number-average molecular weight MN of the preferred copolyesters is
generally in
the range from 5000 to 1 000 000 daltons, in particular in the range from 8000
to
800 000 daltons, and specifically in the range from 10 000 to 500 000 daltons.
The
weight-average molecular weight Mw of the copolyesters preferred in the
invention is
generally in the range from 20 000 to 5 000 000 daltons, frequently in the
range from
30 000 daltons to 4 000 000 daltons, and in particular in the range from 40
000 to
2 500 000 daltons. The polydispersity index MW/MN is generally at least 2, and
is
frequently in the range from 3 to 25, in particular in the range from 5 to 20.
The
PF 70540 CA 02791220 2012-08-27
32
copolyesters are preferably semicrystalline and preferably have a melting
point or
melting range in the range from 80 to 170 C, in particular in the range from
90 to
150 C. The intrinsic viscosity of the copolyesters is typically in the range
from 50 to
500 ml/g, frequently in the range from 80 to 300 ml/g, and in particular in
the range
from 100 to 250 ml/g (determined to EN ISO 1628-1 at 25 C on a 0.5% strength
by
weight solution of the polymer in o-dichlorobenzene/phenol (1:1 w/w)). The
preferred
copolyesters are characterized firstly via high melt viscosity rlo, which at
180 C is
generally at least 60 Pa-s, frequently at least 80 Pa-s, in particular at
least 100 Pa-s,
e.g. from 60 to 20 000 Pa-s, in particular from 80 to 15 000 Pa-s, and
specifically from
100 to 10 000 Pa-s, and via a low acid number, which is less than 5 mg KOH/g
of
polymer, in particular at most 3 mg KOH/g of polymer, and specifically at most
1 mg KOH/g of polymer.
The copolyesters, moreover, naturally have in essence no functional groups
which
make the polymers water-soluble. Accordingly, the number of sulfonic acid
groups in
the copolyester is generally less than 0.1 mmol/g of polymer, in particular
less than
0.05 mmol/g of polymer, or less than 0.01 mmol/g of polymer.
In one specific embodiment of the invention, the polymers to be dispersed
involve a
semiaromatic copolyester, which is also termed copolyester Csp below, and
which is
characterized via the following constitution:
al) from 60 to 80 mol%, frequently from 65 to 80 mol%, in particular from 66
to
75 mol%, based on the total amount of components al) and a2), of at least one
aliphatic dicarboxylic acid or ester-forming derivative thereof, or a mixture
thereof,
and
a2) from 20 to 40 mol%, frequently from 20 to 35 mol%, in particular from 25
to
34 mol%, based on the total amount of components al) and a2), of terephthalic
acid or ester-forming derivatives thereof, or a mixture thereof;
b) from 98 to 102 mol% of at least one diol component b), which is selected
from
1,3-propanediol and 1,4-butanediol and mixtures thereof;
d) from 0.1 to 2% by weight, frequently from 0.2 to 2% by weight, in
particular from
0.3 to 1.8% by weight, and specifically from 0.4 to 1.5% by weight, based on
the
total amount of components al) and a2), in each case calculated as
dicarboxylic
acids, and b), of one or more compounds D which have at least 3
functionalities
which react with carboxylic acid groups or with hydroxy groups to form bonds;
where components al), a2), and b) make up from 80 to 99.8% by weight, in
particular
from 90 to 99.7% by weight, and specifically from 95 to 99.6% by weight, of
the
polyester.
Copolyesters of this type are novel and, probably because of the defined
amount of the
polyfunctional compound D and defined terephthalic acid content, form
particularly
stable dispersions with low viscosity, without any requirement for the use of
PF 70540 CA 02791220 2012-08-27
33
plasticizers, even when melt viscosities or zero-shear viscosities are
relatively high.
Copolyesters Csp having the abovementioned constitution are therefore provided
per
se by the present invention. The present invention likewise provides aqueous
dispersions which comprise a copolyester Csp in the form of dispersed polymer
particles.
Aliphatic dicarboxylic acids al) that can be used are in principle the
aliphatic
dicarboxylic acids mentioned above. It is preferable that component al) is
selected
from succinic acid, adipic acid, sebacic acid, azelaic acid, brassylic acid,
and mixtures
thereof, or else from the ester-forming derivatives thereof. In particular,
component al)
is selected from adipic acid, sebacic acid, and mixtures thereof, or else from
the ester-
forming derivatives thereof.
Component a2) is terephthalic acid and ester-forming derivatives thereof.
The terephthalic acid a2) and the aliphatic dicarboxylic acid al) can be used
in the form
of free acid or in the form of ester-forming derivatives. Particular ester-
forming
derivatives that may be mentioned are the di-Ci-C6 alkyl esters, e.g.
dimethyl, diethyl,
di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl,
diisopentyl, or di-
n-hexyl ester. It is equally possible to use anhydrides of the dicarboxylic
acids.
Component b), the diol, is preferably 1,4-butanediol.
Component d) that can be used in principle comprises the abovementioned
compounds D. It is preferable that compound D is selected from polyols which
preferably have 3,4, or 6 OH groups. Glycerol is particularly preferred.
The copolyesters Csp of the invention can be produced in accordance with the
above
for the copolyesters that are preferred in the invention, composed of
components A, B,
and optionally C and optionally D. In the method generally used, at the start
of the
polymerization reaction, the ratio of the diol (component b)) to the acids
(components i
and ii) is adjusted to be from 1.0 to 2.5:1 and preferably from 1.3 to 2.2:1.
Excess
amounts of diol are drawn off during the polymerization reaction, so that the
ratio
obtained at the end of the polymerization reaction is approximately equimolar.
Approximately equimolar means a diol/diacids ratio of from 0.98 to 1.02:1. It
is
generally advisable to add the crosslinking (at least trifunctional) compounds
D at a
relatively early juncture in the polycondensation reaction.
The copolyesters Csp of the invention can have any desired ratio of hydroxy
and/or
carboxy end groups. The copolyesters Csp of the invention can also be end-
group-
modified. By way of example, therefore, it is possible to acid-modify OH end
groups via
reaction with phthalic acid, phthalic anhydride, trimellitic acid, trimellitic
anhydride,
PF 70540 CA 02791220 2012-08-27
34
pyromellitic acid, or pyromellitic anhydride. Preference is given to
copolyesters Csp of
the invention having acid numbers smaller than 5 mg KOH/g, in particular at
most
3 mg KOH/g, and specifically at most 1 mg KOH/g.
In one preferred embodiment of the invention, compounds C and/or epoxides E
are
also used to produce the copolyesters Csp. Among these, preference is given to
the
difunctional isocyanates and isocyanurates thereof (group c7), bisoxazolines
(group
c5), and also the epoxides E mentioned above. Amount used of the compounds C
and/or D is generally from 0.01 to 4% by weight, preferably from 0.2 to 3% by
weight,
and particularly preferably from 0.35 to 2% by weight, based on the polyester.
The number-average molecular weight MN of the copolyesters Csp is generally in
the
range from 5000 to 1 000 000 daltons, in particular in the range from 8000 to
800 000 daltons, and specifically in the range from 10 000 to 500 000 daltons.
The
weight-average molecular weight Mw of the copolyesters Csp preferred in the
invention
is generally in the range from 20 000 to 5 000 000 daltons, frequently in the
range from
30 000 daltons to 4 000 000 daltons, and in particular in the range from 40
000 to
2 500 000 daltons. The polydispersity index of the copolyesters Csp MW/MN is
generally
at least 2, and is frequently in the range from 3 to 25, in particular in the
range from 5 to
20. The copolyesters Csp are preferably semicrystalline and have a melting
point or
melting range in the range from 80 to 170 C, in particular in the range from
90 to
150 C. The intrinsic viscosity of the copolyesters Csp is typically in the
range from 50
to 500 ml/g, frequently in the range from 80 to 300 ml/g, and in particular in
the range
from 100 to 250 ml/g (determined to EN ISO 1628-1 at 25 C on a 0.5% strength
by
weight solution of the polymer in o-dichlorobenzene/phenol (1:1 w/w)). The
copolyesters Csp are preferably characterized firstly via high melt viscosity
rlo, which at
180 C is generally at least 60 Pa-s, frequently at least 80 Pa-s, in
particular at least
100 Pa-s, e.g. from 60 to 20 000 Pa-s, in particular from 80 to 15 000 Pa-s,
and
specifically from 100 to 10 000 Pa-s, and via a low acid number, which is less
than
5 mg KOH/g of polymer, in particular at most 3 mg KOH/g of polymer, and
specifically
at most 1 mg KOH/g of polymer.
The invention also provides aqueous dispersions of the copolyesters Csp. The
average
diameter of the polymer particles (weight average, determined via light
scattering) in
said dispersions does not generally exceed a value of 10 pm, frequently 5 pm,
in
particular 2000 nm, specifically 1500 nm, being typically in the range from 50
nm to
10 pm, frequently in the range from 100 nm to 5 pm, in particular in the range
from 150
to 2000 nm, specifically in the range from 200 to 1500 nm. It is preferable
that the
diameter of less than 90% by weight of the polymer particles will not exceed
10 pm, in
particular 5 pm, and specifically 2 pm. Particle size is determined in a
manner known
per se via light scattering on dilute dispersions (from 0.01 to 1 % by
weight).
PF 70540 CA 02791220 2012-08-27
In contrast to the dispersions of the prior art, low-viscosity dispersions can
be produced
with the copolyesters Csp of the invention, even when polymer contents are
high.
When the viscosity of the dispersions obtainable in the invention is
determined by the
Brookfield method at 20 C, it is preferable that its value is at most 2 Pa-s,
frequently at
5 most 1 Pa-s, e.g. in the range from 1 to 2000 mPa-s, in particular in the
range from 10
to 1000 mPa-s.
The polymer content of the dispersions obtainable in the invention comprising
the
copolyesters Csp is typically in the range from 10 to 60% by weight,
frequently in the
10 range from 20 to 55% by weight, and in particular in the range from 30 to
50% by
weight.
In another embodiment of the invention, the polymers to be dispersed are
polyalkylene
carbonates, in particular polyethylene carbonates and polypropylene
carbonates.
15 Examples of suitable polyalkylene carbonates are the polyethylene
carbonates which
are known from EP-A 1264860 and which are obtained via copolymerization of
ethylene oxide and carbon dioxide in the presence of suitable catalysts, and
in
particular polypropylene carbonate (see, for example, WO 2007/125039),
obtainable
via copolymerization of propylene oxide and carbon dioxide in the presence of
suitable
20 catalysts.
The polyalkylene carbonate chain can comprise either ether groups or carbonate
groups. The proportion of carbonate groups in the polymer depends on the
reaction
conditions, a particular example being the catalyst used. More than 85%, and
25 preferably more than 90%, of all of the linkages in the preferred
polyalkylene
carbonates are carbonate groups. Suitable zinc catalysts and cobalt catalysts
are
described in US 4789727 and US 7304172. Polypropylene carbonate can moreover
be
produced by analogy with Soga et al., Polymer Journal, 1981, 13, 407-10. The
polymer
is also obtainable commercially, and by way of example is marketed by Empower
30 Materials Inc. or Aldrich.
The number-average molecular weight Mn of the polyalkylene carbonates is
generally
from 70 000 to 90 000 daltons. The weight-average molecular weight Mw is
usually
from 250 000 to 400 000 daltons. The ratio of the ether groups to carbonate
groups in
35 the polymer is from 5 to 90%. Polydispersity (ratio of weight average (Mw)
to number
average (MN)) is generally from 1 to 80, and preferably from 2 to 10. The
polypropylene
carbonates used can comprise up to 1 % of carbamate groups and urea groups.
Other suitable polyalkylene carbonates are chain-extended polyalkylene
carbonates.
Particular chain extenders used for the polyalkylene carbonates are maleic
anhydride,
acetic anhydride, di- or polyisocyanates, di- or polyoxazolines, or the
corresponding
oxazines, or di- or polyepoxides. Examples of isocyanates are tolylene 2,4-
PF 70540 CA 02791220 2012-08-27
36
diisocyanate, tolylene 2,6-diisocyanate, diphenylmethane 2,2'-diisocyanate,
diphenylmethane 2,4'-diisocyanate, diphenylmethane 4,4'-diisocyanate,
naphthylene
1,5-diisocyanate, and xylylene diisocyanate, and in particular hexamethylene
1,6-
diisocyanate, isophorone diisocyanate, or methylenebis(4-
isocyanatocyclohexane).
Particularly preferred aliphatic diisocyanates are isophorone diisocyanate and
in
particular hexamethylene 1,6-diisocyanate. Bisoxazolines that may be mentioned
are
2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane,
1,3-bis(2-
oxazolinyl) propane, or 1,4-bis(2-oxazolinyl) butane, in particular 1,4-bis(2-
oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-
oxazolinyl)benzene.
The amounts preferably used of the chain extenders are from 0.01 to 5% by
weight,
preferably from 0.05 to 2% by weight, particularly preferably from 0.08 to 1%
by weight,
based on the amount of polycarbonate. The number-average molecular weight Mn
of
chain-extended polyalkylene carbonates is typically from 30 000 to 5 000 000
daltons,
preferably from 35 000 to 250 000 daltons, and particularly preferably from 40
000 to
150 000 daltons.
In one embodiment of the present invention, the polymers P used can also
comprise
mixtures of various polymers P comprising ester groups, e.g. mixtures of the
abovementioned copolyesters with polycaprolactones or with polylactides, or
else a
mixture of the polymers P comprising ester groups with other biopolymers, such
as
starch, or with modified biodegradable biopolymers, such as modified starch,
cellulose
ester (e.g. cellulose acetate, cellulose acetate butyrate), or with
biodegradable artificial
polymers, such as polylactide (obtainable for example in the form of EcoPLA
(Cargill)).
In preferred embodiments of the process of the invention, the dispersed
polymers are
biodegradable polymers. Among these are in particular the abovementioned
aliphatic
polyesters, in particular polylactides, and polycaprolactones, and
copolyesters based
thereon, and also the abovementioned aliphatic and aliphatic-aromatic
copolyesters,
where these are composed of the monomers A and B and optionally C and/or D.
Biodegradability to DIN V 54900 means that the polymers decompose in an
appropriate and demonstrable period of time when exposed to the effects of the
environment. The degradation mechanism can be hydrolytic and/or oxidative, and
is
based mainly on exposure to microorganisms, such as bacteria, yeasts, fungi,
and
algae. An example of a method for determining biodegradability mixes the
polymer with
compost and stores it for a particular time. According to ASTM D5338, ASTM
D6400,
EN 13432, and DIN V 54900, C02-free air, by way of example, is passed through
ripened compost during the composting process, and this compost is subjected
to a
defined temperature program. Biodegradability is defined here by way of the
ratio of the
net amount of CO2 liberated from the specimen (after deducting the amount of
CO2
liberated by the compost without the specimen) to the maximum possible amount
of
PF 70540 CA 02791220 2012-08-27
37
CO2 liberated by the specimen (calculated from the carbon content of the
specimen).
Even after a few days of composting, biodegradable polymers generally show
marked
signs of degradation, for example fungal growth, cracking, and perforation.
In another method of determining biodegradability, the polymer is incubated
with a
certain amount of a suitable enzyme at a certain temperature for a defined
period, and
then the concentration of the organic degradation products dissolved in the
incubation
medium is determined. By way of example, by analogy with Y. Tokiwa et al.,
American
Chemical Society Symposium 1990, Chapter 12, "Biodegradation of Synthetic
Polymers Containing Ester Bonds", the polymer can be incubated for a number of
hours at from 30 to 37 C with a predetermined amount of a lipase, for example
from
Rhizopus arrhizus, Rhizopus delemar, Achromobacter sp., or Candida
cylindracea, and
the DOC value (dissolved organic carbon) can then be measured on the reaction
mixture freed from insoluble constituents. For the purposes of the present
invention,
biodegradable polymers are those which after enzymatic treatment with a lipase
from
Rhizopus arrhizus for 16 h at 35 C give a DOC value which is at least 10 times
higher
than that for the same polymer which has not been treated with the enzyme.
The polymer dispersions obtainable by the process of the invention are
likewise
provided by the present invention. They generally feature very fine
distribution of the
polyester particles in the disperse phase.
Generally, the average diameter of the polymer particles (weight average,
determined
via light scattering) does not exceed a value of 10 pm, frequently 5 pm, being
typically
in the range from 50 nm to 10 pm, frequently in the range from 100 nm to 5 pm.
It is
preferable that the diameter of less than 90% by weight of the polymer
particles will not
exceed 15 pm, in particular 10 pm, and specifically 5 pm. Particle size is
determined in
a manner known per se via light scattering on dilute dispersions (from 0.01 to
1 % by
weight).
In contrast to the dispersions of the prior art, low-viscosity dispersions can
be produced
with the process of the invention, even when polymer contents are high. When
the
viscosity of the dispersions obtainable in the invention is determined by the
Brookfield
method at 20 C, it is preferable that its value is at most 2 Pa-s, frequently
at most
1 Pa-s, e.g. in the range from 1 to 2000 mPa=s, in particular in the range
from 10 to
1000 mPa=s.
The polymer content of the dispersions obtainable in the invention is
typically in the
range from 10 to 60% by weight, frequently in the range from 20 to 55% by
weight, and
in particular in the range from 30 to 50% by weight.
PF 70540 CA 02791220 2012-08-27
38
The polymer dispersions obtainable by the process of the invention and the
polymer
dispersions of the invention are suitable for a wide variety of applications
which are
usually relevant to aqueous polymer dispersions. The polymer dispersions
obtainable
by the process of the invention, and the polymer dispersions of the invention,
in
particular those in which the polymer is a copolyester, have particular
suitability for
applications in which biodegradability of the polymer constituent is
desirable. The
aqueous dispersions are particularly suitable as binder constituent in aqueous
binder
compositions, in particular for binder compositions for papermaking, e.g. as
sizes for
paper, in particular as engine sizes, or as surface sizes, as strengtheners
for paper, as
binders for papercoating processes, and also as coatings for producing barrier
coatings
on paper, paperboard or card, and also in binder compositions for producing
nonwovens. The aqueous dispersions are moreover suitable for use in adhesives,
for
example in the form of lamination adhesives, and specifically in the form of
lamination
adhesives for the lamination of plastics foils to flat substrates, such as
paper,
paperboard, card or plastics foils, or for the formulation of active
ingredients. The
polymer dispersions of the invention can also be used for producing foil
materials.
One particularly preferred use of aqueous polymer dispersions of the invention
or
obtainable in accordance with the invention is the use thereof for the
production of
barrier coatings on sheetlike, water-vapor-permeable substrates such as paper,
paperboard or card. For these purposes, the polymer dispersion, optionally
after
formulation with typical auxiliaries, such as thickeners or bactericides, is
applied to the
sheetlike, water-vapor-permeable substrate and is subsequently dried. The
application
rate is generally made such as to result in a coating thickness, calculated as
polymer,
in the range from 1 to 50 g/m2, more particularly in the range from 5 to 30
g/m2. The
formulated dispersion comprises generally not more than 20% by weight, more
particularly not more than 10% by weight, based on the total solids content of
the
formulated dispersion, of subsequently introduced auxiliaries; in other words,
the total
amount of polymer and surface-active substance accounts in general for at
least 80%
by weight, more particularly at least 90% by weight, based on the total solids
content of
the formulated dispersion. The application of the aqueous polymer dispersion
to the
sheetlike, water-vapor-permeable substrate, such as paper, paperboard or card
more
particularly, may take place by means of customary apparatus for applying
aqueous
polymer dispersions to sheetlike substrates, as for example by means of sizing
presses, film presses, blade coaters, airbrushes, doctor blades, by means of
curtain
coating, or using spray coaters.
In preferred embodiments of dispersions of the invention, the dispersed
polymers are
biodegradable polymers. Among these are in particular the abovementioned
aliphatic
polyesters, in particular polylactides and polycaprolactones, and copolyesters
based
thereon, and also the abovementioned aliphatic and aliphatic-aromatic
copolyesters,
where these are composed of the monomers A and B and optionally C and/or D.
PF 70540 CA 02791220 2012-08-27
39
Examples are used below to illustrate the invention.
Analytical methods
To determine zero-shear viscosity Tjo, dynamic viscosity measurement was used
on the
polymer melts at 180 C, using oscillatory low-amplitude shear, at shear rates
in the
range from 0.01 to 500 s-1 and a shear amplitude of 100 Pa to determine
viscosity
curves, and this measurement was used to determine zero-shear viscosityrlo via
extrapolation to a shear rate of 0 s-1. The viscosity curves were determined
by using a
"Dynamic Stress Rheometer (DSR)" from Rheometrics, with plate-on-plate
geometry
(diameter 25 mm, gap 1 mm).
The shear viscosity of the polymer melt under the dispersing conditions was
determined by dynamic viscosity measurement of the polymer melts using a
rotational
rheometer (SR5) from Rhemotrics at the temperature indicated in the examples.
The viscosity of the dispersing medium under the dispersing conditions was
determined by the Brookfield method using a rotational rheometer MCR301 from
Anton
Paar GmbH, at the temperature indicated in the examples, the measurement being
carried out to a shear rate of 1000/s and the viscosity under dispersing
conditions
being determined by extrapolation to the shear rate corresponding to the
example.
Intrinsic viscosity was determined to EN ISO 1628-1 at 25 C on a 0.5% strength
by
weight solution of the polymer in o-dichlorobenzene/phenol (1:1 w/w).
Molecular weights were determined via gel permeation chromatography (GPC) to
DIN 55672-1.
Particle size distribution was determined on a 1 % strength by weight dilution
of the
dispersion, via light scattering at 25 C.
The Brookfield viscosity of the dispersions was determined at 20 C to
DIN EN ISO 2555 using a Physika MCR rotational viscometer with CC 27 Couette
geometry.
Production of copolyesters Csp:
Production example 1: polyester Al
Polybutylene terephthalate adipate, produced as follows: 583.3 g of
terephthalic acid
(27 mol%), 1280.2 g of adipic acid (73 mol%), 1405.9 g of 1,4-butanediol (130
mol%),
PF 70540 CA 02791220 2012-08-27
and 37 g of glycerol (1.5% by weight, based on the polymer) were mixed
together with
1 g of tetrabutyl orthotitanate (TBOT), where the molar ratio of alcohol
component to
acid component was 1.30. The reaction mixture was heated to a temperature of
210 C
and the water produced was removed by distillation at said temperature over a
period
5 of 2 h. The temperature was then increased to 240 C and the system was
evacuated in
stages. Excess 1,4-butanediol was removed by distillation in vacuo (< 1 mbar)
over a
period of 2 h.
The number-average molar mass of the resultant polyester Al was 20 400 g/mol,
and
10 the weight-average molar mass was 140 000 g/mol. Intrinsic viscosity IV was
147.
Melting point was 60 C. Zero-shear viscosity rlo at 180 C was 630 Pa=s. The
acid
number was 0.6 mg KOH/g.
Production example 2: polyester A2
Polybutylene terephthalate adipate, produced as follows: 697.7 g of
terephthalic acid
(35 mol%), 1139.9 g of adipic acid (65 mol%), 1405.9 g of 1,4-butanediol (130
mol%),
and 37.3 ml of glycerol (1.5% by weight, based on the polymer) were mixed
together
with 2.12 ml of tetrabutyl orthotitanate (TBOT), where the molar ratio of
alcohol
component to acid component was 1.30. The reaction mixture was heated to a
temperature of 210 C and the water produced was removed by distillation at
said
temperature over a period of 2 h. The temperature was then increased to 240 C
and
the system was evacuated in stages. Excess 1,4-butanediol was removed by
distillation in vacuo (< 1 mbar) over a period of 1.5 h.
The number-average molar mass of the resultant copolyester was 16 300 g/mol,
and
the weight-average molar mass was 126 000 g/mol. Intrinsic viscosity IV was
131.
Melting point was 80 C. Zero-shear viscosity i1o at 180 C was 370 Pa-s. The
acid
number was less than 1 mg KOH/g.
Production example 3: polyester A3
Polybutylene terephthalate adipate, produced as follows: 697.7 g of
terephthalic acid
(35 mol%), 1139.9 g of adipic acid (65 mol%), 1405.9 g of 1,4-butanediol (130
mol%),
and 37.3 ml of glycerol (1.5% by weight, based on the polymer) were mixed
together
with 2.12 ml of tetrabutyl orthotitanate (TBOT), where the molar ratio of
alcohol
component to acid component was 1.30. The reaction mixture was heated to a
temperature of 210 C and the water produced was removed by distillation at
said
temperature over a period of 2 h. The temperature was then increased to 240 C
and
the system was evacuated in stages. Excess 1,4-butanediol was removed by
distillation in vacuo (< 1 mbar) over a period of 2 h.
PF 70540 CA 02791220 2012-08-27
41
The number-average molar mass of the resultant copolyester was 19 500 g/mol,
and
the weight-average molar mass was 178 000 g/mol. Intrinsic viscosity IV was
161.
Melting point was 80 C. Zero-shear viscosity rlo at 180 C was 1300 Pa=s. The
acid
number was less than 1 mg KOH/g.
Production example 4: polyester A4
Polybutylene terephthalate adipate, produced as follows: 726.8 g of
terephthalic acid
(35 mol%), 1187.4 g of adipic acid (65 mol%), 1464.5 g of 1,4-butanediol (130
mol%),
and 4.12 ml of glycerol (0.2% by weight, based on the polymer) were mixed
together
with 2.21 ml of tetrabutyl orthotitanate (TBOT), where the molar ratio of
alcohol
component to acid component was 1.30. The reaction mixture was heated to a
temperature of 210 C and the water produced was removed by distillation at
said
temperature over a period of 2 h. The temperature was then increased to 240 C
and
the system was evacuated in stages. Excess 1,4-butanediol was removed by
distillation in vacuo (< 1 mbar) over a period of 3 h.
The number-average molar mass of the resultant copolyester was 26 000 g/mol,
and
the weight-average molar mass was 140 000 g/mol. Intrinsic viscosity IV was
157.
Melting point was 80 C. Zero-shear viscosity rlo at 180 C was 720 Pa-s. The
acid
number was less than 1 mg KOH/g.
Production example 5: polyester A5
Polybutylene terephthalate adipate, produced as follows: 1095.2 g of
terephthalate
(47 mol%), 700 g of 1,4-butanediol (65 mol%), and I ml of glycerol (0.05% by
weight,
based on the polymer) were first mixed together with 1.1 ml of tetrabutyl
orthotitanate
(TBOT), and the mixture was heated to 160 C. The methanol formed was distilled
off
over a period of 1 h. The reactor was then cooled to around 140 C. Added
thereto
subsequently were 929.5 g of adipic acid (53 mol%), 700 g of 1,4-butanediol
(65 mol%), and 1 ml of glycerol (0.05% by weight, based on the polymer),
together with
1.04 ml of tetrabutyl orthotitanate (TBOT). The reaction mixture was heated to
a
temperature of 190 C and the water produced was removed by distillation at
said
temperature over a period of 1 h. The temperature was then increased to 240 C
and
the system was evacuated in stages. Excess 1,4-butanediol was removed by
distillation in vacuo (< I mbar) over a period of 1 h.
The number-average molar mass of the resultant copolyester was 21 000 g/mol,
and
the weight-average molar mass was 59 000 g/mol. Intrinsic viscosity IV was
106. Zero-
shear viscosity rlo at 180 C was 136 Pa-s. The acid number was less than I mg
KOH/g.
PF 70540 CA 02791220 2012-08-27
42
Production example 6: polyester A6
Polybutylene terephthalate adipate, produced as follows: 71.1 g of the sodium
salt of
the dimethyl ester of 3-hydroxysulfonylisophthalic acid (dimethyl-NaSIP, 2
mol%),
1048.6 g of terephthalate (45 mol%), 700 g of 1,4-butanediol (65 mol%) were
first
mixed together with 1.1 ml of tetrabutyl orthotitanate (TBOT), and the mixture
was
heated to 160 C. The methanol formed was distilled off over a period of 1 h.
The
reactor was then cooled to around 140 C. Added thereto were 929.5 g of adipic
acid
(53 mol%), 700 g of 1,4-butanediol (65 mol%), and 2 ml of glycerol (0.1 % by
weight,
based on the polymer), together with 1.04 ml of tetrabutyl orthotitanate
(TBOT). The
reaction mixture was heated to a temperature of 190 C and the water produced
was
removed by distillation at said temperature over a period of 1 h. The
temperature was
then increased to 240 C and the system was evacuated in stages. Excess
1,4-butanediol was removed by distillation in vacuo (< 1 mbar) over a period
of 1.5 h.
The number-average molar mass of the resultant copolyester was .......
Intrinsic
viscosity IV was 137. Zero-shear viscosity rlo at 180 C was 3280 Pa=s. The
acid
number was less than 1 mg KOH/g.
Production example 7 (copolyester B1, chain-extended):
Polybutylene terephthalate adipate, produced as follows: 92.7 kg of
terephthalate
(40 mol%), 58.5 kg of 1,4-butanediol (65 mol%), and 0.1 kg of glycerol (0.05%
by
weight, based on the polymer) were mixed together with 0.014 kg of tetrabutyl
orthotitanate (TBOT), and the mixture was heated to 160 C. The methanol formed
was
distilled off over a period of 1 h. The reactor was then cooled to around 140
C.
Admixed were 83.3 kg of adipic acid (60 mol%), 58.5 kg of 1,4-butanediol (65
mol%),
and 0.1 kg of glycerol (0.05% by weight, based on the polymer), together with
0.014 kg
of tetrabutyl orthotitanate (TBOT). The reaction mixture was heated to a
temperature of
190 C and the water produced was removed by distillation at said temperature
over a
period of 1 h. The temperature was then increased to 250 C and the system was
evacuated in stages. Excess 1,4-butanediol was removed by distillation in
vacuo, at
8 mbar, over a period of 50 min. Subsequently, at 240 C, 0.9 kg of
hexamethylene
diisocyanate was metered in slowly over a period of 1 h.
The number-average molar mass of the resultant copolyester was 32 000 g/mol,
and
the weight-average molar mass was 170 000 g/mol. Zero-shear viscosity 'no at
180 C
was 4010 Pa-s.
PF 70540 CA 02791220 2012-08-27
43
Production example 8 (copolyester B2, chain-extended):
A polybutylene terephthalate adipate, produced as follows: 69.4 kg of dimethyl
terephthalate (35 mol%), 90.2 kg of adipic acid (65 mol%), 117 kg of 1,4-
butanediol,
and 0.4 g of glycerol (0.2% by weight, based on the polymer) were mixed
together with
0.028 kg of tetrabutyl orthotitanate (TBOT), where the molar ratio of alcohol
component
to acid component was 1.30. The reaction mixture was heated to a temperature
of
180 C, and was reacted at said temperature for 6 h. The temperature was then
increased to 240 C, and the excess dihydroxy compound was removed by
distillation in
vacuo over a period of 3 h. 0.9 kg of hexamethylene diisocyanate was then
metered
slowly into the mixture over a period of 1 h at 240 C.
The number-average molar mass of the resultant copolyester was 32 000 g/mol,
and
the weight-average molar mass was 170 000 g/mol. Zero-shear viscosity 110 at
180 C
was 2510 Pa-s.
Production examples 9 to 13:
The copolyesters of production examples 9 to 13 were produced by analogy with
production example 1 (and, respectively, production example 7). The molar
constitutions of the copolyesters are collated in Table 2, and their
properties are
collated in Table 3. The acid number was in all cases less than 1 mg KOH/g.
Table 1:
Prod. Ex. T [mol%] 1) 2) A [mol%] 1) 2) BD [mol%] 1) 2) G [% by wt.] 1) 3)
9 35 65 100 1.5
10 27 73 100 0.12
11 (comp) 4) 0 100 100 1.5
125) 44 56 100 0.1
13 47 53 100 0.1
1) T = terephthalic acid, A = adipic acid, BD = 1,4-butanediol, G = glycerol
2) based on the total amount of terephthalic acid + adipic acid in the
polyester
3) based on the total weight of the polyester
4) comparative example
5) chain-extended, by analogy with production example 5
PF 70540 CA 02791220 2012-08-27
44
Table 3:
Prod. Ex. MN Mw IV 1) MP [ C] 2) qo 3)
[Pa's]
9 18 400 230 000 190 80 2500
22 600 76 300 130 64 164
11 (comp) 4) 25 000 180 000 160 60 350
12 32 000 130 000 180 n.d. 5600
13 28 000 108 000 134 n.d. 753
1) intrinsic viscosity
2) melting point
3) zero-shear viscosity at 180 C
5 4) comparative example
Production of the aqueous polyester dispersions
Dispersion example 1:
The emulsion trials were carried out in an experimental system comprising (a)
a
Cavitron CD 10 rotor-stator mixer from Cavitron, with two inlets and one
outlet, (b) a
Tech-line E16 T single-screw extruder from Dr. Colin GmbH, connected by way of
a
heated line to the first inlet of the rotor-stator mixer, (c) a heated,
pressure-tight storage
vessel for the aqueous dispersion medium, provided on the outlet side with a
gear
pump for conveying the dispersion medium, where the pump was connected by way
of
a pressure-tight line to the second inlet of the rotor-stator mixer, a cooler,
connected by
way of a pressure-retaining system to the outlet of the rotor-stator mixer,
and also a
storage vessel, for collecting the dispersion, attached to the outlet of the
cooler. The
rotor-stator mixer was operated at 4000 rpm.
An amount of 0.3 kg/h of pellets of the aliphatic-aromatic copolyester from
production
example 12 were drawn by way of the feed hopper into the single-screw
extruder,
where they were melted at 200 C. From there, the melt was conveyed into the
rotor-
stator mixer. At the same time, by means of the gear pump, a 5% strength by
weight
solution of polyvinyl alcohol (Kuraray Poval 235) heated to 180 C in water was
conveyed at a rate of 2.5 kg/h into the rotor-stator mixer. The temperature in
the rotor-
stator mixer was from 165 to 170 C, and the pressure at the outlet of the
mixer varied
from 8 to 12 bar. The aqueous emulsion produced at the outlet of the mixer was
cooled
to 20 C by means of the cooler. This method gave an aqueous, solvent-free
dispersion
with 11 % by weight polyester content. The particle-size-distribution curve
determined
by means of light scattering exhibited a main peak with a maximum at 700 nm
and a
further peak with a maximum at 1000 nm.
PF 70540 CA 02791220 2012-08-27
Dispersion example 2:
The rotor-stator mixer used comprised a 3-stage in-line-dispersion apparatus
which
had three rotor-stator-mixer units arranged in series on a shared rotor, where
the first
5 and third stage of the apparatus had elements in the form of screw threads
and the
second and third stage had shear elements in the nature of toothed rings.
An amount of 0.83 kg/h of the copolyester from production example 10 (rlo =
164 Pa-s)
was drawn continuously by way of the feed hopper into the single-screw
extruder
10 (Tech-line E 16 T from Dr. Colin GmbH), where it was melted at 135 C. The
polymer
melt was fed to the first-stage dispersion apparatus (3000 rpm). The shear
rate was
8960 s-1 and the polymer viscosity at this shear rate was 35 Pa s. At the same
time, a
7% strength by weight aqueous solution of a partially hydrolyzed polyvinyl
alcohol
(Kuraray Poval 224E) which comprised 1 % by weight of an anionic surfactant
15 (Emulphor FAS 30 from BASF SE) was fed into the three stages of the in-line-
dispersion apparatus. The viscosity of the aqueous solution of polyvinyl
alcohol and
Emulphor FAS 30 was 0.041 Pa s. The solids contents in the first and second
stage
were 47% by weight and, respectively, 35% by weight. The solids content in the
third
stage was set to 29% by weight. The temperature in the first and second stage
was
20 135 C, and in the third stage it was 120 C. The total residence time was 2
min. After it
had left the third stage, the dispersion was quenched to 20 C by means of a
cooling
bath.
The resultant dispersion exhibited the following particle-size distribution:
dso = 10.9 pm
25 andd43=6.2pm.
The pH of the dispersion was 5.5, and the viscosity (at 25 C) was 80 mPa=s.
Dispersion example 3:
30 The rotor-stator mixer used comprised a 12-stage in-line-dispersion
apparatus, the
apparatus having shear elements in the nature of toothed rings.
An amount of 1.2 kg/h of the copolyester from production example 5 (too = 136
Pa-s)
was drawn continuously by way of the feed hopper into the single-screw
extruder
35 (Tech-line E 16 T from Dr. Colin GmbH), where it was melted at 150 C. The
polymer
melt was fed to the first-stage dispersion apparatus (4000 rpm). The shear
rate was
12 566 s-1 and the polymer viscosity at this shear rate was 17 Pa s. At the
same time, a
7% strength by weight aqueous solution of a partially hydrolyzed polyvinyl
alcohol
(Kuraray Poval 224E) which comprised 1% by weight of an anionic surfactant
40 (Emulphor FAS 30 from BASF SE) having a solution viscosity of 0.038 Pa s
was fed
into the in-line-dispersion apparatus in such a way that the solids contents
in the first
and fourth stage were 55% by weight and, respectively, 45% by weight. The
solids
PF 70540 CA 02791220 2012-08-27
46
content in the tenth stage was set to 40% by weight. The temperature in the
first ten
stages was 150 C; in the eleventh and twelfth stages it was 130 C. The total
residence
time was 1.2 min. After it had left the final stage, the dispersion was
quenched to 20 C
by means of a cooling bath.
The resultant dispersion exhibited the following particle-size distribution:
d90 = 3.8 pm
and d43 = 2.3 pm.
The pH of the dispersion was 5.5, and the viscosity (at 25 C) was 1.6 Pa-s.
Dispersion example 4:
The rotor-stator mixer used comprised a 3-stage in-line-dispersion apparatus
which
had three rotor-stator-mixer units arranged in series on a shared rotor, where
the first
and third stage of the apparatus had elements in the form of screw threads and
the
second and third stage had shear elements in the nature of toothed rings.
An amount of 0.45 kg/h of the copolyester from production example 6 (rlo =
2810 Pa-s)
was drawn continuously by way of the feed hopper into the single-screw
extruder
(Tech-line E 16 from Dr. Colin GmbH), where it was melted at 140 C. The
polymer melt
was fed to the first-stage dispersion apparatus (3000 rpm). At the same time,
a 2%
strength by weight aqueous solution of a partially hydrolyzed polyvinyl
alcohol (Kuraray
Poval 224E) was fed into the three stages of the in-line-dispersion apparatus.
The
solids contents in the first and second stage were about 52% by weight and,
respectively, 40% by weight. The solids content in the third stage was set to
30% by
weight. The temperature in the first and second stage was 140 C, and in the
third stage
it was 120 C. The total residence time was 2 min. After it had left the third
stage, the
dispersion was quenched to 20 C by means of a cooling bath.
The resultant dispersion exhibited a multimodal particle-size distribution
with peaks at
d43 = 0.33 pm, d43 = 2.5 pm, and d43 = 6.5 pm. The pH of the dispersion was
5.2, and
the viscosity (at 25 C) was 60 mPa-s.
Application of the aqueous polyester dispersions as barrier coating on paper
Application example I
Wood-free base paper (from Magnostar, 70 g/m2) was coated on one side using a
manual coating bar (#3) at a speed stage of 5 with the aqueous polyester
dispersion
from dispersion example 4. The coated paper was then dried in a drying cabinet
at
110 C for 1 min. This gave a coated paper having a polyester coating of 16
g/m2
(solids).
PF 70540 CA 02791220 2012-08-27
47
Application example 2
Wood-free base paper (from Magnostar, 58 g/m2) was coated twice on one side at
a
speed of 10 m/min, using a laboratory coating machine (BASF, in-house design)
with
the aqueous polyester dispersion from dispersion example 4, and was
immediately
dried by means of IR radiation. This gave a coated paper having a polyester
coating of
14 g/m2 (solids).
Testing of the barrier properties
The barrier properties of the polyester-dispersion-coated papers from
application
examples I and 2 were subsequently investigated using the Oil Penetration
Test. For
this test, the coated side of the paper was wetted with 2 ml of oleic acid.
The paper was
then stored for a relatively long time at 60 C. The reverse of the coated
paper was then
inspected for spotting.
The surface of the coated paper from application example 1 showed no (i.e.,
0%) spots
after I h of storage at 60 C. This corresponds to an oil penetration of 0% at
60 C for
1 h. The uncoated Magnostar base paper (70 g/m2) showed 100% oil penetration
after
just 5 min of storage at 60 C.
The surface of the coated paper from application example 2 showed no (i.e.,
0%) spots
after 16 h of storage at 60 C. This corresponds to an oil penetration of 0% at
60 C for
16 h. The uncoated Magnostar base paper (58 g/m2) showed 100% oil penetration
after just 5 min of storage at 25 C.
