Note: Descriptions are shown in the official language in which they were submitted.
` 2~2~77
Mo3485
LeA 21,298
AQUEOUS POLYMER DISPERSIONS AND
A PROCESS FOR THEIR PRODUC~ION ~ -
BACKGROUND OF THE INVENTION ;~i ~
. .:
Field of the Invention
This invention relates to a new aqueous polymer dispersion
wherein the disperse phase is basecl on a mixture of certain
chlorine-containing polymers and certain chlorine-free
copolymers of olefin1cally unsaturated monomers and to a
process for their production.
10Description of the Prior Art
Chlorinated, natural or synthetic polymers, such as
chlorinated natural rubber, chlorinated polyethylene and
chlorinated rubber obtained by chlorination of synthetic rubber
(homopolymers and copolymers of butadiene and/or isoprene), are
known. These chlorine-containing polymers are used for various
; àpplications, including the production of coating compositions
for various substrates, the production of adhesives and the
production of printing inks. The raw materials in question are
` generally processed from~organic solutions wherein the
viscosity can unfortunately increase considerably with
~; increasing molecular weight of the chlorinated polymers, so
~ that in many cases the raw materials can only be processed from
;~ highly dilute solutions, i.e., those having a solvent content above 50% by weight.
Reducing the organic solvent content to make the end
products, particularly paints, more environmentally friendly is
not possible in practice. In addition, there are very narrow
limits to the use of relatively low-viscosity chlorinated
, rubbers because~the savingiof solvent in the final preparation
iS minimal and, in addition, the chlorinated rubbers of
different viscosity stages are distinguished by differences, in
some cases, considerable differences, in their property
spectrum. ~ -
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Chlorine-containing polymers dissolved in organic
solvents, especially chlorinated rubbers dissolved in organic
solvents, can be emulsified in water. However, the solids
content of the solution to be emulsified is limited because,
with increasing concentration, manipulatability becomes
increasingly limited due to the increase in viscosity. For
example, if the viscosity of the chlorinated rubber solut;on in
organic solvents exceeds a value of about 8000 mPa.s, further
processing at room temperature is seriously complicated or even
impossible~
Viscosities of this order are achieved, for example in the
case of solutions in solvent naphtha, with a chlorinated rubber
having an average molecular weight of approximately 60,000 (all
~ molecular weight data for the chlorinated polymers are based on
:: 15 the weight average molecular weight, Mw, determined on a 0.1%
; solution at 20QC by the interference Archibald method using an
ultracentrifuge) and a solids concentration of 60% by weight at
approximately 23DC. A chlorinated rubber having an average
molecular weight of 85,000 reaches this viscosity range when
` 20 adjusted to a solids concentration of approximately 50% by
weight at approximately 23C~ while a product having an average
molecular weight of 135,000 and a solids concentration of 50%
by weight has to be heated to 60 to 70C in order to reduce the
viscosity to this range, which is necessary for further
: 25 processing.
If a 50% by weight solution of a chlorinated rubber having
an average molecular weight of 85,000 in solvent naphtha 100 is
mixed with water containing an emulsifier by using shear forces
(for example in a dissolver), an emulsion is initially formed
` i ` 30 which is organophilic in the outer phase, but hydrophilic in
the inner phase. This means that dilutability with water in
the absence of shear forces and cleaning of the units used for
~; application with~water is not possible. If more emulsifier-
containing water is added to the water-in-oil emulsion (w/o
35: emulsion) in the presence of shear forces, the emulsion
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ultimately undergoes phase reversal, so that an oil-in-water
emulsion (o/w emulsion) is formed. Depending upon the type of
chlorinated rubber, the type and quantity of solvent and the
application of shear forces, the solids concentration at the
phase reversal stage is about 20 to 30~0 by weight. This means
that aqueous o/w emulsions of chlorinated rubber in water can
have a maximum s017ds content of about 30% by weight which, of
course, seriously impairs the economy of such aqueous emulsions
because at least 70% of the transport and storage costs are
o attributable to the organic solvent and water.
Accordingly, an object of the present invention was to
develop an aqueous binder containing chlorinated polymers which
can be diluted with water, contains at most 22% by weight of
organic solvents and has a solids content of at least 30% by
weight.
This object was solved by the process according to the
invention, which is described in detail hereinafter and the
aqueous polymer dispersions resulting therefrom.
SUMMARY OF THE INVENTION
The present invention relates to an aqueous polymer
dispersion containing at most 22% by weight of organic solvents
and 30 to 60% by weight of dispersed polymers, characterized in
that the dispersed polymers contain
A) 20 to 80% by weight of chlorinated, natural or synthetic
polymers having a chlorine content of 60 to 70% by weight
and
B) 20 to 80% by weight of non-chlorinated polymers.
The present invention also relates to a process for the
production of an aqueous polymer dispersion characterized in
that an at least 50% by weight solution in an inert solvent of
a chlorinated, natural or synthetic polymer A) having a
chlorine content of 60 to 70% by weight is mixed with water in
the presence of external emulsifiers to form a water-in-oil
emulsion and subsequently the water-in-oil emulsion is combined
with an aqueous dispersion of at least one non-chlorinated
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polymer to form an oil-in-water dispersion, wherein the type of
and quantitative ratios between the individual components are
selected such that the resulting dispersion has a solvent
content of at most 22% by weight, a dispersed polymer content
of 30 to 60% by weight and a weight ratio of chlorine-
containing polymers A) to non-chlorinated polymerç B) of 80:20
to 20:80.
DETAILED DESCRIPTION OF THE INVENTION
Starting materials for the process according to the
o invention are A) chlorinated polymers and B) chlorine-free
polymers.
The chlorinated polymers are either chlorinated olefins,
particularly chlorinated polyethylene, having a chlorine
content of 60 to 70% by weight or chlorinated rubbers having a
chlorine content of 60 to 70% by weight, preferably 64 to 68%
by weight, and an average molecular weight of up to 185,000,
preferably 60,000 to 185,000 and more preferably 60,000 to
135,000. In the context of the invention, the expression
"chlorinated rubber" is intended to encompass both chlorinated
20 . natural rubber and also chlorinated homopolymers and copolymers
of butadiene and isoprene.
` The chlorine-free polymers B) include, ;n particular,
"polyacrylates," i.e., copolymers prepared from at least one
alkyl ester of acrylic or methacrylic acid with other
i 25 olefinically unsaturated monomers such as styrene, metha-
crylonitrile, acrylonitrile, methacrylamide, acrylamide,
methacrylic acid, acrylic acid and/or monomers containing
groups capable of crosslinking reactions such as N-methoxy-
methyl methacrylamide or N-methoxymethyl acrylamide.
30 i Copolymers of
a) 20 to 50% by weight styrene,
~ b) 30 to 70% by weight of at least one C1 6 alkyl ester of
; acrylic or~methacrylic acid,
c) O to 10% by weight acrylic acid and/or methacrylic acid
and
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d) 0 to 20% by weight of other olefinically unsaturated
monomers,
wherein the percentages add up to 100, are particularly
preferred.
The chlorine-free polymers are generally copolymers
produced by radical polymerization which are used in the form
of aqueous dispersions having solids contents of 30 to 60% by
weight in the process according to the invention. The carboxyl
groups of the copolymers are generally present in the
dispersions in amine-neutralized or, more particularly,
ammonia-neutralized form. In addition, the dispersions
generally contain external emulsifiers in quantities of about
0.2 to 2.0% by weight. Polymers which are particularly
suitable as component B) include the aqueous polymer
dispersions marketed by Bayer AG, Leverkusen, under the names
Ercusol 160 and Ercusol AS 250.
In addition, suitable auxiliaries for carrying out the
process according to the invention include:
- Inert solvents, preferably those which do not have to be
20......... identified by law as hazardous materials. Suitable
solvents include aromatic hydrocarbon solvents which are
commercially available as "solvent naphtha," esters (such
as ethyl or butyl acetate)5 ketones (such as methyl ethyl
ketone or methyl isobutyl ketone) or mixtures of such
sol vents.
- Plasticizers for the chlorine-containing polymers A) such i
as adipic acid dibutyl ester, phthalic acid dibutyl ester,
phosphoric acid tributyl ester or trihexyl ester,
chlorinated paraffins or C10 14 alkane sulfonic acid
30 i phenyl esters present and commercially available as
homolog mixtures (e.g., the plasticizer marketed by Bayer
AG, Leverkusen, under the name Mesamoll).
- Emulsifiers for the production of a w/o emulsion of the
chlorinated polymers such as ethoxylation products of
substituted phenols, for example isononyl phenol Dr
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bis(phenylethyl)-phenol, in which 10 to 50, preferably 10
to 20 ethylene oxide units, in the form of polyether
chains are present per molecule.
- Foam inhibitors such as "Entschaumer PA 49," a product of
Bayer AG, or Fsamex I488, a product of Th. Goldschmidt AG.
The first step of the process according to the invention,
i.e., preparation of the aqueous w/o emulsion of the
chlorinated polymer, may be carried out in two ways.
In a first variant, a highly concentrated solution of a
chlorinated polymer in which the solvent content corresponds to
a maximum viscosity at 23C of 10,000, preferably at most 6000
mPa.s, is initially introduced and plasticizers, emulsifiers or
other additives are optionally added thereto. Water9
preferably demineralized water, is then introduced into the
dispersion with intensive stirring, an emulsifier optionally
being added to the water in a quantity sufficient to emulsify
the chlorinated~polymer unless such a quantity of emulsifier
was incorporated in the organic solution beforehand. A w/o
emulsion is formed through the uniform introduction of the
:`: 20 water in the presence of shear forces. The introduction of
water is stopped when the solids content of the w/o emulsion
has fallen to 30 to 60% by weight, preferably 40 to 50% by
weight.
In a second variant of the first step of the process
according to the invention, a solution of a chlorinated polymer
in~an inert solvent having a solids content of more than 50% by
weight, preferably at least 60% by weight, is heated to
approximately 60 to 80C and emulsified in water at that
temperature. The emulsifier required for emulsifiability is
~` i 30 incorporated beforehand iniat least one of the two components.
In this variant, an o/w emulsion is initially formed. The
phase reversil to w/o~only takes place during the continuing
introduction of the solution of the chlorinated polymer and at
the latest when the entire quantity of solution has been
~` 35 emulsified. The amount of solution corresponds to a solids
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content of the resulting w/o emulsion of at least 30% by
weight, preferably at least 40% by weight.
Regardless of the method used to prepare the w/o emulsion
formed as an intermediate stage, it is subsequently mixed with
polymer dispersion B). The water content or polymer dispersion
B) causes a phase reversal from w/o to o/w without the sollds
content of the resulting dispersion being significantly
reduced.
In accordance with the process of the present invention,
the type of components and the ratios in which they are blended
are selected such that the resulting dispersion has a maximum
solvent content of 22% by weight; a total content of dispersed
polymers A) and B) of 30 to 60% by weight; and a ratio by
weight between the polymers A) and B) of 80:20 to 20:80,
preferably 60:40 to 40:60.
The polymer dispersions according to the invention
~- prepared in this way, without further additives, are valuable
coating compositions for various substrates. However, they may
also be blended with thP auxiliaries and additives typically
` 20 used in coatings technology such as pigments, foam inhibitors,
pigment dispersant and flow control agents. Particularly
interesting corrosion-inhibiting properties are obtained by the
addition of bitumen emulsions maintaining a weight ratio of dispersed polymers to
bitumen of from O,S:l to 3:1. Thus steel plates coated with a composi~ion containing
. 25 a dispersion according to the inventionanda bitumen emulsion (ratio by weight of
dispersed polymers to bitumen = 1:1) showed no visible change after 42 days in a :
salt spray test (3% NaCl).
`~ The following examples are intended to illustrate the
invention. All parts and percentages are by weight unless
i 30 otherwise indicated.
Examples
The following starting materials were used in Examples 1
to 6 below:
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Chlorinated rubber l:
Chlorinated synthetic rubber (poly-1,4-cis-isoprene), molecular
we;ght 85,000, chlorine content: 66% by weight.
Chlorinated rubber II:
Chlorinated synthetic rubber (poly-1,4-cis-isoprene), molecular
weight 135,000, chlorine content: 66% by weight.
Plasticizer:
Cl0 14 alkane sulfonic acid phenyl ester present as a homolog
mixture.
Emulsifier:
Adduct of 13 moles of ethylene oxide with 1 mole of bis-(1-
phenylethyl)-phenol.
Polvmer disDersion I:
A dispersion having a solids content of 42% by weight and based
on a copolymer which is the reaction product of
; ~ 37.8% by weight styrene
55.9% by weight N-butyl acrylate
5.4% by weight methacrylic acid
0.9% by weight N-methoxymethyl methacrylamide
- 20 . The dispersion was prepared by the process according to US-PS
2,978,432. The carboxyl groups were neutralized with ammonia.
PolYmer dispersion II:
A dispersion having a solids content of 50% by weight and based
on a copolymer which is the reaction product of
:~: 25 53.5% by weight N-butyl acrylate
5.0% by weight methacrylic acid
40.0% by weight styrene
1.5% by weight N-methoxymethyl methacrylamide.
The dispersion was prepared by the process according to US-PS
30 i 2,978,432. The carboxyl groups were neutralized with ammonia.
Foam Inhibitor:
Commercial foam inhibitor (Foamex 1488, a product of Th.
l~ Goldschmidt AG)
¦ Solvent naphtha 100:
Commercial solvent mixture containing aromatic alkyl-
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substituted hydrocarbons.
ExamDles 1 to 2 (Table 1)
The chlorinated rubbers were d~ssolved in solvent naphtha
5 at room temperature to form a 47.5% by weight solution. The
plasticizer was then stirred in, where indicated. The
quantities of emulsifier and foam inhibitor set forth were then
added and homogenized. The quantit1es of demineralized water
shown were then introduced slowly and uniformly under the
0 effect of shear forces in a Pendraulik laboratory dissolver of Pendra~ik Maschinen
und Apparate GmbH, Bad Munder, Germany. A w/o emulsion was
formed. After adequate homogenization the polymer dispersion, -
containing the amounts of emulsifier and foam inhibitor set
forth, was added with continued stirring. The addition of the
polymer dispersion resulted in phase reversal from w/o to o/w. --
15 After a final emulsification period of about 20 minutes, the
production was complete. The particle diameter of the
dispersed phase was at most 500 nm. The dispersions obtained
showed pseudo-plastic behavior and were white to pale yellowish
in color. When dried through evaporation of the water and
20 . organic solvent, the dispersions formed light translucent films ~
having a matt-silk surface. They were especially suitable as -
aqueous binders for the production of coating compositions for
concrete or steel.
ExamDle 3 (Table 1)
2s This Example differs from Examples 1 and 2 in that the
dissolving and emulsification process was carried out at a
temperature of 60-C. The increase in temperature allowed the
solids concentration of the chlorinated rubber solution to be
increased to ~0% by weight and the organic solvent content to
be reduced to 13% by weight.
ExamDle 4 (Table I)
This Example differs from Examples 1 and ~ in that the
dissolving and emulsification process was carried out at 60-C,
which allowed a chlorinated rubber of higher molecular weight
and also higher viscosity to be used.
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Table 1
Formulat;ons for Examples 1 to 4
1 2 3 4
Chlorinated rubber I195.4 195.4 195.5
Chlorinated rubber II 195.4
Solvent naphtha 100216.0 216.2 130.1 216.0
Total parts 411.4 411.8 325.6 411.4
% Sol;ds 47.5 47.5 60.0 47.5
Operating temperature~C 23 23 60 60
Plasticizer 39.2 - 39.3 39.2
Emulsifier 22.5 19.6 22.5 22.5
Foam inhibitor 2.9 2.9 - 2.9
Incorporation by emulsification of
Demineralized water 55.9 78.3 145.6 55.9
Foam inhibitor 1.9
After homogenization,
incorporation by emulsification in the
mixture of
Polymer dispersion I465.2 464.2 465.1 465.2
Emulsifier 19.6 :-
Foam inhibitor 2.9 2.9 2.9
Total parts 1000.0 1000.0 1000.0 1000.0
% Solids 45.4 43.2 45.4 45.4
% Solvent 21.6 21.6 13.0 21.6
% Water 33.0 35.2 41.6 33.0
;:
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Examples 5 and 6 (Table 2)
Examples 5 and 6 differ from the preceding examples in
that the chlorinated rubber solution was adjusted to a solids
content of 60% by weight and the dissolving process and also
5 further processing were carried out at 80C. In the preceding
examples a w/o emulsion was init;ally prepared by stirr;ng in
water. The w/o emulsion underwent phase reversal to an o/w
phase after the addition of the polyacrylate dispersion.
However, in Examples 5 and 6 the heated and also viscosity-
reduced chlorinated rubber solution in an aqueous emulsifier
solution was first emulsified to an o/w emulsion which
underwent phase reversal to a w/o emulsion during the addition.
Phase reversal back to o/w occurred during the addition of the
polymer dispersion. Dispersions having higher solids contents
and reduced contents of organic solvents were obtained in this
manner.
.
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Table 2
::
Formulations of Examples 5 and 6
S 6
Chlorinated rubber I 212.0 231.3
Solvent naphtha 100 141.0 153.8
Parts by weight 353.0 385.1
% Solids 60.0 60.0
lo . Operating temperature C 80 80
Plasticizer 42.8 46.7
~:~ Emulsifier 24.3 26.5
Incorporation by emulsification
of demineralized water 60.4 65.9
After homogenization,
;ncorporation by emulsification of
Polymer dispersion I 519.5
~: : Polymer dispersion II - 475.8
Total Parts 1000.01000.0
% Solids 49.7 54.2
` ~ ~ 25 X Solvent 14.1 15.4
% Water 36.2 30.4
:
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Application ExamDles
In the following Applica$ion Examples, the dispersions of
Examples 1 to 6 were formulated with a pigment slurry and the
other starting materials set forth in Table 3 to form
5 ready-to-use coat;ng compositions.
The pigment slurry contained a mixture of
95.23 parts Pigmentverteiler A ("Pigment Dispersant
A", a product of BASF AG, Ludwigshafen), 3% in
demineralized water
133.34 water
: 791.90 titanium dioxide, rutile
9.53 Foam Inhibitor
: 1000.00 total parts
.
Table 3 (Composition of coating compositions)
Products of Examples
1 2 3 4 5 6
0 P;gment slurry 1000 1000 1000 1000 1000 1000
:: Foam Inhibitor 2.8 2.8 2.8 2.8 2.8 2.8
: ~ Thickener 33.8 33.8 33.8 33.8 33.8 33.8
: Water 154.0 288.0
Dispersion1773 1773 1773 1773 1619 1485
Total Parts2809.62809.62809.6 2809.6 2809.6 2809.6
Acrysol RM 8, a product of Rohm & Haas, 10% in water
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Formulations of the coating compositions (Table 4)
Table 4 (quantities in %)
; ~ 1 2 3 4 5 6
:
Binder
incl. additives 29.0 27.6 29.0 29.0 29.0 29.0
Pigment 27.1 27.1 27.1 27.1 27.1 27.1
Total solids56.1 54.7 56.1 56.1 56.1 56.1
Org. solvent13.6 13.6 8.2 13.6 8.1 8.1
Water 30.3 31.7 35.7 30.3 35.8 35.8
Total 100.0 100.0 100.0 100.0 100.0 100.0
All the coating compositions thus prepared showed pseudo-
plastic behavior and dried through evaporation of the water and
; ; the residual organic solvent to form a film with a homogeneous,
matt-silk surface. The films adhered very firmly inter alia to
steel, concrete and lightweight boards. They demonstrated good
0 corrosion-inhibiting behavior in accelerated salt-spray tests.
" ~ The good~result obtained after 2000 hours of accelerated
weathering in a Xeno 1200 Weather-O-Meter suggests excellent
weathering behavior.
Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be
understood that such detail is solely for that purpose and that
variations can~be made therein by those skilled in the art
` without departing~from the spirit and scope of the invention ;
except as it~may be limited by the claims.
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