Note: Descriptions are shown in the official language in which they were submitted.
~6~59
CASE 95-E515/CA
Thermoplastic PolYmer Blends
The invention relates to thermoplastic polymer blends on the basis of degradablealiphatic polyesters with melting points below 100C.
As a rule, aliphatic polyesters have a melting point below 100C, mostly below 80C,
with molecularweights of less than 100.000 g/mol. The materials are soft and sticky and
are therefore mostly employed as melt adhesives. They cannot be processed into blown
film. If the polyester contains aromatic monomers, such a terephthalic or isophthalic acid,
the melting point increases with the amounts added and the ability to produce blown films is
improved. None of the polyesters with aromatic components are aliphatic polyesters and
are therefore excluded. This applies to the preponderant number of polyesters. Because
of their aromatic components they are not degradable.
The biodegradability of plastics is a further problem which has been strongly
researched for a long time at great effort, because the ability of plastics to remain stable
over long periods of time poses great ecological problems.
The majority of polymer materials for daily life and for industrial and agricultural
applications are products which are produced from blown film. Unfortunately, plastics which
can be worked into blown film, in particular in conventional blown film installations, display
no biodegradability, while biodegradable plastics have up to now not been suitable for
producing blown film.
However, there are many areas of use where the employment of biodegradable pla-
stics makes sense, particularly where a total system becomes biodegradable because of
this. Typical examples of this are compost bags and diapers.
Polycaprolactone (PCL) is an aliphatic polyester with a low melting point and iscompletely biodegradable.
Polycaprolactone is commercially available up to an average molecular weight of
approximately 100.000 g/mol. However, none of the types are suitable for producing blown
film directly. The production of films is only successful via the flat film process (JP 05-105
771, JP 05-132 572).
In connection with film production by means of a film blowing installation used for
producing sacks and bags, the particular problem lies in the low melt stability of PCL and
the low melting point which requires low processing temperatures.
2~6~0~9
:
5.10.95 / hkl -.2.-
Greater requirements are demanded in particular from the melt stability and theextensibility of the melt when producing blown films. The comparison between PE and PP
should be noted as a known example for the differences in the suitability of blown films.
Other thermoplastic polymers must be added to achieve the required processing
stability and economic production speeds. However, the amounts are important and must
be selected such that the decomposition of the film material, for example in the compost, is
not hampered.
One skilled in the art is aware that the production of flat films as well as fiber production
from pure polycaprolactone already works.
Polymers blended with polycaprolactone with average gravimetric molecular weights of
70.000 are proposed for the production of stretched flat films in Patent Publication JP 05-
132 572 A2/1993.
JP 04-148 918 A2/1992 describes the production of blown films with polycaprolactone
P 767. It was noted that it was impossible to achieve the required melt stabilities as well as
the required extensibility either P 767 with an Mn range around 50.000 or P 787 with an Mn
range around 80.000. It is indeed possible to draw off a tubing within a very narrow
processing window. However, th~e tubing cannot be blown open, so that the customary
transverse stretching at ratios of 1:2 to 1:4 in relation to the nozzle cross section is not
possible.
JP 05-132 572 A/1993 describes the production of polycaprolactones with avera~e
gravimetric molecular weights of 10.000 to 50.0000. Commercially available molecular
weights lie maximally at 100.000 g/mol, which are unsuitable for blown film processing. It is
not known whether higher molecular weights are suitable for producing blown films.
Furthermore, a substrate material for active lacquer and agricultural materials is
described, for example, in JP 57-185 344 A/1982, with PCL as the substrate material, which
is not produced as a blown film.
KR 93 01990 B describes an orthopedic bandage of PCL ~ filler + wax + EAA, whosemanufacturing process has not been disclosed. As a rule such materials are thicker than
100 mm and are produced as flat foils. The effects of fillers on the blown film production is
negatively judged here.
The product disclosed in EP 0 635 994 A1 protects biodegradable flat foils of aliphatic
PES (PCL) and starch, whose disadvantages are sensitivity to moisture and poor
mechanical properties. There are no suggestions regarding blown film production.US Patenf 4,912,174 recommends PCL and PU (diol ~ isocyanate) produced in situ for
producing compressed plates of a thickness of 3 to 4 mm for orthopedic use. No
suggestions are found regarding foil production and/or blown film suitability.
~ ~16~9
5.10.95 / hkl -.3.-
US Patenf 5,200,247 claims degradable flat foils of PCL + PVA, 75 - 90 / 25 - 10%, slot
die extruded, cylinder temperature 350 to 450F, extruder 2.5 inches, 65 rpm, 30 m per
min., foil thickness 1 to 25 mil (1/1,000 in.), which are mechanically stretched.
Standard polymers, such as PE, PET, PS, PU, PVC, PP, PC are the main components,which are equipped with additives which increase degradability for improving degradability.
Here, aliphatic polyesters are merely used as additives (biodegradable safening materials),
so that the processing properties of the blends are derived from the main components.
Blown films are claimed in WO 93/00399, wherein the thermoplastic strength (TPS)(15 -
35%) is prescribed as a necessity. Poor mechanical properties and low water resistance as
well as a strong effect of moisture on the mechanical properties result from this.
Blends with 60 - 90% PCL, 40 to 10% terpolymer with 60 to 80% styrene proportionand optionally 0 to 15% maleic acid anhydride for extrusion on Brabender 230C, and again
the production of plates for orthopedic use are claimed in WO 91/09909. The disclosure
contains no suggestions as to foil suitability and no foil properties. Degradability is not of
interest.
The products from DE-OS 32 20 324 represent a synthetic resin mass, 100 parts PCL
+ 10 to 70 parts resin + 1 to 30 parts PVC. The intended use is as a core material for
shoes. The main properties are bending resistance and stickiness, use as a pressed foil or
hot melt and the production of pressed foils of a thickness of 1.4 mm. In every case the
main property of stickiness has a negative effect on the tube separation in the production of
blown films.
Thus, the prior art only shows the production of blown films of PCL with TPS. These
products can be blown into films, however, they display great changes in their properties
under the effect of moisture. Sealing properties become worse, tear resistance is reduced.
Films below 20 ~lm cannot be technically produced. The addition of TPS reduces the tear
resistance and stretchability, so that it would always be necessary to use films of double
thickness to obtain comparable resistance.
It is therefore the object of the invention to avoid the disadvantages of the previously
sketched prior art and to make available molding materials on the basis of polyesters, which
are per se unsuitable for blow molding, but which permit the manufacture of industrial
products, in particular for agriculture and for daily life, in particular those which are
biodegradable over a reasonable period of time, i.e. rot, as well as a process for their
manufacture and their use.
The object of the invention is attained by means the use of thermoplastic polymer
blends on the basis of degradable aliphatic polyesters with melting points below 100C of
the following composition:
- 21610~
5.10.95 / hkl -.4.-
<1> 50 to 94.99 weight-% of an aliphatic polyester or copolyester of at least one
omega-lactone or at least one omega- hydroxycarboxylic acid with 4 to 12 C atoms, and/or
of aliphatic diols with 2 to 12 C atoms and aliphatic dicarboxylic acids with 4 to 12 C atoms,
~ ll> 50 to 5 weight-% of at least one polymeric auxiliary component with polar groups,
selected from the group of polyamides, polyurethanes, ethylenevinyl alcohol copolymers,
ethylenevinyl acetate copolymers, ethylene acrylic acid copolymers7 polyvinyl acetate,
modified polyolefines, polystyrenes, polyacrylnitrils, polybutadienes, polyisoprenes, their
copolymers and their mixtures, and
<lll~ 1 to 0.01 weight-% of at least one additive from the group of polar lubricants, polar
waxes which are compatible with the components <1> and cll>, or silicic acid,
wherein the the components cl>, ~ and <lll~ always add up to 100 weight-%,
and which are suitable for producing blown films,
wherein the blends selectively contain further auxiliary materials in accordance with the
prior art.
It has now been surprisingly found that of the different polymeric auxiliary components
only a few have sufficient compatibility with PCL to achieve the necessary melt stability for
the production of blown films. It has also been surprisingly found that additional
components are required to obtain high mechanical stability in the films.
Because of this low processing temperature of the aliphatic polyesters there is only a
small temperature difference to the ambient temperature. The small temperature difference
results in problems of heat dissipation, which cause strong instabilities of the tube and lead
to blockage of the films. The attainment of the object is to find suitable components in
particular with whose aid polyester and particularly PCL can be modified in such a way that
films can be produced in film blowing installations.
Thus, put more succinctly, it is the object of the invention to provide molding materials
suited for the production of blown film in the form of thermoplastic polymer blends, in
particular on the basis of biodegradable plastic, namely aliphatic polyesters which as such
cannot be produced by blow molding, in particular on the basis of lactones andlor
polyesters on the basis of aliphatic dicarboxylic acids and diols and/or hydroxy carboxylic
acids, their manufacture and their use
The aliphatic polyesters <1~ are biodegradable and are preferably composed of
lactones and/or aliphatic dicarboxylic acids and diols and/or omega-hydroxy carboxylic
acids, the polymeric auxiliary materials <ll> contain polar groups, preferably have a melting
point of below 170C and are preferably selected from the group of polyamides,
polyurethanes, ethylenevinyl alcohol copolymers, ethylenevinyl acetate copolymers,
ethylene acrylic acid copolymers, polyvinyl acetate, modified polyolefines, as well as
polystyrenes, polyacrylnitrils, polybutadienes, polyisoprenes, as well as their copolymers
~ 2 1 ~ 9
.
5.10.95 ~ hkl -.5.-
and/or mixtures of the polymers and/or copolymers, and the additives clll> are selectedfrom from the group of polar lubricants and/or waxes which are compatible with the aliphatic
polyesters and/or copolyesters andtor are pyrogens or precipitated silicic acids, in particular
silicic acid aerogels.
In addition to the 100% mentioned, the polymeric blends can contain customary
auxiliary materials, such as dyes, fillers, flame-proofing agents, stabilizers, modifiers and
the like.
The use of this class of polyesters is of particular interest for the manufacture of foils
and films which can be further processed into, for example, compost bags, carrying bags or
bags of all types, but also many other products, such as vegetable and fruit packaging,
magazine and book packaging or, in cut-open form, as diaper film, in particular backing
sheets for diapers, as wrapping or stretch films, stretch foils, shrink wrap, adhesive foils,
laminated films, textile laminates, wood and paper coatings, metering bags, pest traps,
carriers of active substances for horticulture and agriculture, as binder material for paper
making, for producing molding materials with natural fibers, such as wood pulp, flax, ramie,
wastepaper, and for modifying of degradable foam, expanded shaped products and loose
fill, as melt adhesives for powder applications as well as the production of fibers, fabrics,
non-wovens, in particular for industrial and agricultural use, as well as for producing twine,
yarns, binder cables for horticulture and agriculture, as blend components for modifying
degradable materials, such as thermoplastic starch material, hydroxycarboxylic acid
polyester, polyester amides, polyurethanes, cellulose molding materials, cellulose acetate
molding materials, starch acetate molding materials, polyvinylpyrrolidone molding materials,
polyester carbonate molding materials, and the like. The advantage of these products lies
in that this type of material rots in the environment or in compost. Furthermore, an aliphatic
polyester material which is suitable for films represents an ideal blend components for
thermoplastic starches and other degradable polymers.
The process for manufacturing blends with auxiliary components, whose melting points
are above 170C, consists in that the polymeric auxiliary materials <ll> and the additives
<Ill) are pre-extruded with maximally 30 weight-% of polyester and are formed into pre-
granules, and in a second step these pre-granules are extruded with the remaining amount
of polycaprolactone <1> to form the final granules.
The high-melting auxiliary components ~ll> and the additives <Ill> are preferably
melted in the extruder (first half of the screw) and the polyester <1~ is extruded into the melt
via a side extruder (second half of the screw).
Also preferably, the pre-granules from step 1 are processed directly into blown films as
a granule mixture with polycaprolactone or with other thermoplastic processable
biodegradable granules.
~ 6~0~i9
5.10.95 / hkl -.6.-
Since the polycaprolactones of the types CAPA 650, CAPA 680 and Tone P 787 couldnot be processed into blown film, various granule mixtures and compounds were produced
by means of twin-screw extruders. These granule mixtures and compounds were proces-
sed in a film blowing installation of the Collin company, tested for mechanical properties and
the bag properties determined. Copolyamides with melting points between 80 and 160C,
ethylene acrylic acid copolymeres with melting points between 60 and 100C, polyester
urethanes preferably containing aliphatic polyester polyester diols and low-melting ethylene-
vinyl alcohol copolymers with an ethylene content between 40 and 60 weight-% and which
then have a melting range bet~,veen approximately 150 to 170C, are ideal blend
components as added polymers ~
Modified polyolefins, such as maleic acid anhydride, grafted polyethylenes (PE),polypropylenes (PP) or polycaprolactones (PCL), as well as polystyrenes (PS), polyacryl
nitrils (PAN), polybutadienes (PB) and/or polyisoprenes (Pl), as well as their copolymers can
be used as promising polymeric auxiliary components ~Il>. Of particular interest are
polyester, polyamide, copolyamide, polyurethane, in particular PU with polycaprolactone
flexible segments. Since in only the fewest cases one component is sufficient, the mixtures
with stepped compatibilities are mainly of interest.
An improvement in homogenity is achieved when polymers with similar melting points
are pre-extruded together and are compounded in a second step or in the second half of
the extruder srew with polycaprolactone. Granule production can take place directly if all
components have melting points similar to polycaprolactone or if they are partially soluble in
each other. In these cases even the production of films directly from the granule mixture is
possible.
The polycaprolactone or other polyesters, i.e. aliphatic polyesters, which cannot be
processed into blown films, are used in excess between 50 and < 95%, in particular
between 75 and < 95%. The polymer additives necessary for processing are used at 5 to
50%, particularly at 25 to 5%. It is possible to employ lubricants of all types in weight
proportions of 0.1 to 1% to reduce an adhesive tendency. Polyester waxes, polyamide
waxes and polar waxes of natural origin are particularly effective.
The reduction of the separation problem of the film tube can be performed mechani-
cally, for example by the addition of spherical mineral separating agents such as pyrogenic
or precipitated silicic acid, in particular silicic acid aerogels, for example Aerosil and Silwett
in amounts of 0.01 to 0.1 weigh-%. Mixtures of polycaprolactone and polyester urethane
are of particular interest which, in a mixture of 84/16 weight-% have a brilliant transparent
appearance after cold stretching of the blown films and can be employed above all in the
field of flexible, highly transparent protective films. Biodegradable polycaprolactone and
microbially "unstable" polyester urethane, in particular with polycaprolactone diol flexible
~ 2~ 6~Q~
5.10.95 / hkl -.7.-
segments and aliphatic diisocyanate rigid segments, represent a technically high-value
alternative for compostable films.
In place of isocyanate hard blocks which cross-link the elastomeric flexible segments
thermoplastically, other block components capable of cryslalli~ation are advantageously
usable, in particular polyester and polyamide with melting points above 100C. Ideally,
monomers are selected which have 2 to 6 C atoms between the ester and the amide
groups.
If the extrusion of the aliphatic polyesters with the polyester urethanes or polyester
amides is performed at higher temperatures, for example higher than 200C. trans-esterifi-
cation or trans-amidation processes can take place, so that the aliphatic polyesters can be
built into the segmented block polymers. It is possible in this way to modify the material
used in such a way that it has all desired properties. If granules are formed from it, the user
can employ these directly for blow molding.
The following examples will explain the invention.
Formulation and processing examples are summarized in Tables 1 and 2. The
components in parentheses were each pre- extruded and subsequently were directlyprocessed into films in the form of a granule mixture together with the polycaprolactone.
In Example 18 the parentheses for ethylvinyl alcohol indicate that 80 weight-%
ethylvinyl alcohol were pre-extruded together with 20 weight-% of glycerin.
Examples 1 to 3 (Table 1)
Polycaprolactone of the types CAPA 650, CAPA 680 and Tone P 787 are sequentiallyprocessed in a blown film installation. It was possible to achieve stable extrusion conditions
in various temperature profiles in the range between 70 to 100~C for various extruder rpm
and draw-off speeds. It was not possible to expand the film tube. If the nozzle temperature
rises above 120C, the melt stability at full cooling output is so small that the tubing tears
under its own weight. At temperatures below 70C the melt becomes wax-like and can no
longer be blown open.
A special CAPA 650 modified by grafting with maleic acid anhydric for making the foil
(Interrox company) was tested in Example 2b. The material also could not be blown open
and is unsuitable for the production of blown film.
Examples 4 and 5 (Table 1)
The combination of ethylene acrylic acid polymer (EAA) (Primacor) and copolyamide
(CoPA) (CF 6S) (EMS Chemie) processes well, but with slight homogeneity problems. Bags
were produced to assess weldability. The bags were filled with compressed air and caused
to burst. In the second test the bags were filled with water and the amount at which the bag
bursts was measured.
~ 2 ~ 9
5.10.95 / hkl -.8.~
F: The film fails
N: The welding seam fails.
Example 6 (Table 1)
The additional admixture of a polyester urethane component improves the homogeneity
of the film, but results in considerable differences in strength in the linear and transverse
directions. This variant processes excellently and is suitable for the production of blown
films.
Example 7 (Table 1)
EAA by itself is not capable to provide a usable degree of processibility to PCL.
Distinct problems arise in the area of homogeneity and in particular of stability of the tube.
Strong pulsations prevent the formation of blown film.
Examples 8a and 8b (Table 1)
The combination of PCL and polyester urethane results in very satisfactory mechanical
strength while completely utilizing the stretchability of PCL. Because of strong pulsations
the tubing stability is insufficient.
In Example 8b the two components were pre-extruded and processed into a blown film
in the second step. By means of this the tubing stability is clearly improved during
processing, although the mechanical values drop slightly. Greater amounts of water were
clearly handled in a bag filling test. This variant is particularly suitable for admixing with
thermoplastic starch and at 20% (in relation to the total material) shows an extremely high
tear propagation resistance in the linear direction of 460 N/mm in the dry state.
Example 9 (Table 2)
In addition to Lucalen (modified PE), polycaprolactone grafted with maleic acid
anhydride was used. By means of this it is possible to create good compatibility of PCL with
Lucalen. However, the problems in the area of tubing stability cannot be removed.
Example 10 (Table 2)
Ethylenevinyl alcohol and two variants of polyester urethane are pre-extruded together
with the amide wax Amide E and are subsequently extruded together with Tone P 787 as a
granule mixture to form a foil. A very good processibility is achieved by means of this. The
foils have very satisfactory linear and transverse strength along with very good bag
properties. This compound is the especially prefered embodyment. In the water fill test a 30
llm film sealed to a bag can hold 17 liter of water.
~lS1059
5.10.95 / hkl -.9.-
Example 11 (Table 2)
CoPA (CF 6S), EVAL and a polyester urethane were pre-extruded and processed intoa film as a granule mixture together with PCL. In spite of very good bag properties, pro-
blems in homogenity and stability of the tube occur. However, the final mechanical proper-
ties of this film are very good.
Example 12 (Table 2)
Analogous to Example 10, but without pre-extrusion and without lubricants. This
variant displays clear disadvantages in stability of the tube and has reduced mechanical
properties in comparison with Example 10.
Examples 13 to 17 (Table 2)
In combination with EAA (Primacor 5980), Tone P 787 displays very good mechanical
properties of the films, but because of its unstable behavior of the tube is not suitable for
producing films. Examples 15 to 17 display unsatisfactory stability of the tube.
Example 18 ~Table 2)
Analogous to Example 10 and Example 12. In this case, 80 weight-% of ethylvinyl
alcohol ~EVOH) were pre-extruded together with 20 weight-% of glycerin and subsequently
processed in the form of a granule mixture, together with the remaining components in
accordance with Table 2, into blown film. Foil production proceeds very well, wherein high
mechanical strength was obtained, together with a very high degree of tear propagation
resistance, but a moderate water-fill result.
21610~9
t
5.10. 95 / hkl -.10 . -
., ~ ~ r~ ~n _~ m jo ~ Oo" o o
o ~ n O o ~ + ~ + ~ r~
~ o o o ~ ~ ~ ~ o o j ~ 5 ~
~ co
3 ~ ~? o ~ $ ~
o n ~ oO co 00 ~ +
o~
~ ~ o. -~ ~ o Oo~
a~
o O ~ ~O ,~ ~~ 0 . . o o~ co 1~
.Q g
o ~n ~ ~~ j ~ + +
o ~n oo ~n ~ r~ . ~ +
o~O ~o ~o ~ ~o 5 V, ," o. ~ ~ æ ~ - ~
,~ U U U ~
C~ . .
Y 11 E - 1 ~
, ~16~059
5.10.95 / hl~l -.11.-
U~ ~ '? '?.~ ~`I ~r t` u~ ~ o U~ 1 ~ ~ ~ ~ ~
~ o~ O. ~ + C ~ ,,o, oo ~ 2 + ~ ~
~O _ _ _~ æ
~ O," ~0 ~ ~ `O $ ~ O + ` ~ ~3 + ~
~ _ ~o
~ i 2 ~ "' ~ V~ $ I o,, +
o ~ ~ 2 _ i ~ 3 ! + ~ 5` 53 ~o t
æ
~ ~ ~o 5~ ~ 8 .~~ ~ ~ jo ~ C~
a~
Q r.( 8 '-
~ r ~8 ~ O~ ~ + o + 8 ~ ~ ~~ ~~ + ~
V~ ~ 00 t t`l ~ t~ $ o O + ~7 V~ +
0~ ~ O t~l tO t ~ $ ~ 5~
L~ tr~7 ~ o ` ~ ~ tt~l O $ ;~ .n ;~
a` ;~ ~ a~ o~ o~ ~ ~ u u
R R ~g G
U ~ ~3 ~ U t P.~ ~ t ~ t t~ t,; t t ~ ; t
~ 21610~9
5.10.95 / hkl -.12.-
The plastic materials employed in these examples and listed in Tables 1 and 2, wherethey are identified by their commercial designations, are identified in detail as follows:
PCL Polycaprolactone Mn 50 000 - 100 000
Starch material thermoplastic starch granules
PE Polyethylene Commercially avaiable
PP Polypropylene Commercially avaiable
PS Polystyrene Commerciallyavaiable
PAN Polyacrylnitril Commercially avaiable
PB Polybutadiene Commercially avaiable
Pl Polyisoprene Commercially avaiable
PU Polyurethane Commercially avaiable
EAA Polyethylenacrylic acid Commercially avaiable
CoPA (CF6S) Copolyamide 6/12 (EMS-Chemie1 Commercially avaiable
EVAL=EVOH Ethylenvinyl alcohol Ethylene content44 %
CAPA 650 Polycaprolactone Mn 50 000 ~/mol
CAPA 650 *Exp* Polycaprolactone Modifier(lnterox)
CAPA 680 Polycaprolactone Mn 80 000 g/mol
TONE P787 Polycaprolactone Mn 80 000 - 100 000 g/mol
CF6S Copolyamide 6/12 EMS-Chemie
Primacor 5980 Ethylenacrylic acid DOW
Primacor XU Ethylenacrylic acid DOW
Lucalen A2920M Polyethylene graKed BASF
EVAL E105 Ethylenevinyl alcohol (44% ethylene) Kuraray
Estane 58206 Polyesterurethane Goodrich
Estane 54625 Polyesterurethane Goodrich
Armid E Armide Akzo
Sarmawax E34146 Typ of wax unknown Sandoz/ltaly
B9429, P787 Polycaprolactone graftet (maleicacid EMS-Chemie
B9430, P787 anhydride) EMS-Chemie
