Blends comprising a polyphenylene ether, a fluorine-containing olefinic polymer and a vinyl aromatic alkyl (meth) acrylate copolymer

The invention relates to polymer mixtures which comprise a polyphenylene ether, a fluorine-containing olefinic polymer or copolymer and a vinyl-aromatic alkyl(meth)acrylate copolymer. Polymer mixtures having improved properties are obtained by the addition of a di- or triblock copolymer with one or more blocks derived from conjugated diene units and with one or more blocks derived from vinylaromatic units.

The invention relates to a polymer mixture which comprises a polyphenylene 
ether, a fluorine-containing olefinic homopolymer or copolymer, and a 
vinylaromatic alkyl(meth)acrylate copolymer. 
Polymer mixtures of the type described hereinbefore are known from T. 
Ouhadi et al, Molecular Design of Multicomponent Polymer Systems, Journal 
of Polymer Science: Part B: Polymer Physics, Vol 24, 973-981 (1986). The 
known polymer mixtures comprise a blend of a rubber-modified PS/PPO.RTM. 
mixture and polyvinylidene fluoride to which a linear 
poly(styrene-b-alkyl(meth)acrylate) has been added. As a 
poly(styrene-b-alkyl(meth)acrylate) is used the product as it is obtained 
by sequential anionic polymerisation of styrene and alkyl(meth)acrylate. 
The method of preparing this linear product is described in EP-A-0 076 
539. The addition of poly(styrene-b-alkyl(meth)acrylate) results in a 
change in morphology, improves the tensile strength and the elongation at 
fracture. 
From experiments performed by the Applicants, however, it has been found 
that the impact strength, in particular the notch impact strength 
according to IZOD is reduced by the addition of a 
poly(styrene-alkyl(meth)acrylate) copolymer. 
The invention is based on the discovery that, by the addition of a further 
constituent, namely a block copolymer as defined hereinafter as 
constituent D, a polymer mixture is obtained having an even improved 
elongation at fracture and a considerably improved impact strength. The 
tensile strength is only little reduced. 
The polymer mixture according to the invention is characterised in that the 
polymer mixture comprises: 
A. 10-90% by weight of a polyphenylene ether, 
B. 10-90% by weight of a fluorine-containing olefinic homopolymer or 
copolymer, the weight percentages of A and B being calculated with respect 
to the sum of the quantities by weight of A plus B, 
C. 1-80 parts by weight of a vinylaromatic alkyl(meth)acrylate copolymer, 
D. 1-20 parts by weight of an, optionally partially hydrogenated, block 
copolymer having one or more blocks derived from conjugated diene units 
and having one or more blocks derived from vinylaromatic units, 
E. 0-200 parts by weight of a styrene homopolymer and/or rubber-modified 
styrene polymer, and 
F. 0-50 parts by weight of conventional additives, the parts by weight of 
C, D and E being calculated per 100 parts by weight of A+B. 
The polymer mixture according to the invention preferably comprises as 
constituent C a non-linear vinylaromatic alkyl(meth)acrylate copolymer. 
The polymer mixture according to the invention preferably comprises 30-70% 
by weight of constituent A and 70-30% by weight of constituent B, the 
weight percentages of A and B being calculated with respect to the sum of 
the quantities by weight of A plus B. 
The polymer mixture according to the invention preferably comprises 1-50 
parts by weight of constituent C per 100 parts by weight of A plus B. 
The polymer mixture according to the invention preferably comprises as 
constituent B a polymer or a copolymer which is built up for more than 25 
mol % of units derived from vinyl fluoride and/or vinylidene fluoride. 
The polymer mixture according to the invention comprises at any rate the 
following constituents: 
A. a polyphenylene ether, 
B. a fluorine-containing olefinic polymer or copolymer, 
C. a vinylaromatic alkyl(meth)acrylate copolymer, and 
D. a block copolymer. 
The polymer mixture according to the invention may moreover comprise one or 
more of the following constituents: 
E. a styrene homopolymer or rubber-modified styrene homopolymer, and 
F. conventional additives. 
A. POLYPHENYLENE ETHERS 
Polyphenylene ethers are compounds known per se. For this purpose, 
reference may be made to the U.S. Pat. Nos. 3,306,874, 3,306,875; 
3,257,357 and 3,257,358. Polyphenylene ethers are usually prepared by an 
oxidative coupling reaction--in the presence of a copper amine complex--of 
one or more two-fold or three-fold substituted phenols, homopolymers and 
copolymers, respectively, being obtained. Copper amine complexes derived 
from primary, secondary and/or tertiary amines may be used. Examples of 
suitable polyphenylene ethers are: 
poly(2,3-dimethyl-6-ethylphenylene-1,4-ether) 
poly(2,3,6-trimethylphenylene-1,4-ether) 
poly[2-(4'-methylphenyl)phenylene-1,4-ether] 
poly(2-bromo-6-phenylphenylene-1,4-ether) 
poly(2-methyl-6-phenylphenylene-1,4-ether) 
poly(2-phenylphenylene-1,4-ether) 
poly(2-chlorophenylene-1,4-ether) 
poly(2-methylphenylene-1,4-ether) 
poly(2-chloro-6-ethylphenylene-1,4-ether) 
poly(2-chloro-6-bromophenylene-1,4-ether) 
poly(2,6-di-n-propylphenylene-1,4-ether) 
poly(2-methyl-6-isopropylphenylene-1,4-ether) 
poly(2-chloro-6-methylphenylene-1,4-ether) 
poly(2-methyl-6-ethylphenylene-1,4-ether) 
poly(2,6-dibromophenylene-1,4-ether) 
poly(2,6-dichlorophenylene-1,4-ether) 
poly(2,6-diethylphenylene-1,4-ether) 
poly(2,6-dimethylphenylene-1,4-ether) 
Copolymers, for example, copolymers derived from two or more phenols as 
used in the preparation of the homopolymers mentioned hereinbefore, are 
also suitable. Furthermore suitable are graft copolymers and block 
copolymers of vinylaromatic compounds, for example, polystyrene and of 
polyphenylene ether as described hereinbefore. 
B. FLUORINE-CONTAINING OLEFINIC POLYMERS OR COPOLYMERS 
Fluorine-containing olefinic polymers or copolymers are known per se. Only 
polymers behaving like thermoplastic synthetic resin may be used in the 
polymer mixtures according to the invention. 
Particularly suitable are the homo- or copolymers which are built up for 
more than 25 mol %, even more preferably more than 45 mol %, from units 
derived from vinyl fluoride and/or vinylidene fluoride. Examples of such 
homopolymers are polyvinylidene fluoride, polyvinyl fluoride or mixtures 
of these two homopolymers. Copolymers built up from units derived from 
vinylidene fluoride and vinyl fluoride are also suitable. Further suitable 
copolymers are the copolymers which on the one hand comprise units derived 
from vinylidene fluoride and/or vinyl fluoride and which on the other hand 
comprise units derived from hexafluoropolypropylene and/or 
chlorotrifluoroethylene and/or tetrafluoroethylene. 
C. VINYLAROMATIC ALKYL(METH)ACRYLATE COPOLYMERS 
Vinylaromatic alkyl(meth)acrylate copolymers are to be understood to mean 
herein copolymers which comprise units derived from a vinylaromatic 
compound, for example, styrene and units derived from alkyl(meth)acrylate, 
for example, methylmethacrylate. More in particular those compounds are 
meant which comprise one or more blocks built up from several units 
derived from a vinylaromatic compound and one or more blocks built up from 
several units derived from an alkyl(meth)acrylate. Various structures are 
possible, for example, linear or non-linear polymeric molecules. 
The first type of polymers has been used, for example, in the polymer 
mixtures as they are described the article mentioned hereinbefore in 
Journal of Polymer Science. The preparation of this type is described in 
EP-A-0 076 539. 
Suitable non-linear polymeric molecules are, for example, the polymers 
having a comb structure. These can be obtained, for example, by grafting 
several chains of a polyvinyl-aromatic compound, for example, polystyrene 
on a chain of a polyalkyl(meth)acrylate. In order to obtain a polymer 
having a comb structure it is also possible to use a polystyrene having a 
reactive terminal group. The terminal group is chosen so that it can be 
incorporated in a polyalkyl(meth)acrylate chain. An example of such a 
polystyrene is a polystyrene having terminal alkyl(meth)acrylate groups. 
Non-linear polymers having a main chain derived from a vinylaromatic 
monomer and having polyalkyl(meth)acrylate side chains are also suitable. 
In the vinylaromatic alkyl(meth)acrylate copolymer as it is used in the 
polymer mixture according to the invention, the relative quantity of 
vinylaromatic units to alkyl(meth)acrylate units may be chosen between 
very wide limits, for example, between 5:95 and 95:5 preferably between 
25:75 and 75:25. 
Examples of suitable alkyl(meth)acrylates are methyl- or ethylmethacrylate 
and methyl- or ethylacrylate. In general, acrylates or methacrylates 
having an alkyl group which comprises 1-6 carbon atoms are to be 
preferred. 
D. BLOCK POLYMER 
The polymer mixture according to the invention comprises an, optionally 
partially hydrogenated, block copolymer having one or more blocks derived 
from conjugated diene units and having one or more blocks derived from 
vinylaromatic units. 
The known block copolymers having blocks derived from butadiene and/or 
isoprene and having blocks derived from styrene may be used in particular. 
These block copolymers may be partially hydrogenated, which means that the 
blocks derived from the conjugated diene units then are hydrogenated for 
the greater part, while the styrene blocks are not hydrogenated. 
All the known types of this kind of block copolymers are to be considered: 
linear diblock- and linear triblock copolymers, radial block copolymers 
and so on. 
In addition to the constituents mentioned hereinbefore sub A, B, C and D, 
the polymer mixture may comprise one or more of the following 
constituents: 
E. Styrene homopolymer and/or rubber-modified styrene polymer and/or 
F. conventional additives. 
E. STYRENE HOMOPOLYMER AND/OR RUBBER-MODIFIED STYRENE POLYMER 
These are meant to include any polymer which is built up for more than 75 
mol % from units derived from units derived from styrene and the 
rubber-modified modifications thereof. In particular are meant: crystal 
clear polystyrene built up for more than 100 mol % from units derived from 
styrene units and so-called high impact polystyrene. In so far as these 
polymers comprise further copolymerisable units in addition to styrene, 
they are always random copolymers. This in contrast with the constituents 
mentioned sub C and D which may be referred to as block copolymers. 
F. CONVENTIONAL ADDITIVES 
In addition to the constituents mentioned hereinbefore, the polymer mixture 
according to the invention may comprise one or more of the following 
constituents: fillers, reinforcing fibres, agents to improve the flame 
resistance, stabilisers, dyes and/or pigments. As stabilisers may be used 
the stabilisers generally known for polyamides. 
The polymer mixture according to the invention may be prepared according to 
any method known for the preparation of polymer mixtures. The various 
constituents are preferably mixed by means of melt extrusion.

The invention will now be described in greater detail, by way of example, 
with reference to the ensuing specific examples. 
EXAMPLE I 
Comparative Examples A, B and C 
Two samples of a non-linear poly(styrene-methyl-methacrylate) were prepared 
via a free radical polymerisation of methyl methacrylate and 
2-polystyrylethylmethacrylate having a molecular weight of 13,000. In this 
manner two copolymers were obtained: copolymer I having a methyl 
methacrylate content of 64% by weight and a molecular weight of 58,000 and 
a copolymer II having a methyl methacrylate content of 68% by weight and a 
molecular weight of 64,000. The structure of the copolymers I and II 
consists of a long polymethacrylate chain with polystyrene side chains 
(comb structure). 
The copolymers I and II were mixed in an extruder adjusted at an average 
temperature of 270.degree. C. with one or more of the following 
constituents: 
a polyphenylene ether, namely poly(2,6-dimethylphenylene-1,4-ether) having 
an intrinsic viscosity of approximately 49 ml/g measured at 25.degree. C. 
in chloroform; 
polyvinylidene fluoride having a melt flow index according to ASTM D 1238 
of 4 g/min. at 230.degree. C. and a load of 5 kg; 
a styrene/ethylene-butylene/styrene triblock copolymer having a weight 
ratio styrene to ethylene-butylene of 27 to 73. The total molecular weight 
is 74,000; the molecular weight of each of the styrene blocks is 10,000 
and of the ethylene butylene block it is 54,000. 
The quantities used are recorded in Table A hereinafter. 
Test pieces for determining the tensile strength at fracture, the 
elongation at fracture, and the IZOD notch impact value were manufactured 
(by injection moulding) from the resulting polymer mixtures. The values 
found are also recorded in the table hereinafter. 
TABLE A 
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Example I A B C 
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Composition 
(parts by weight) 
polyphenylene ether 
45 45 45 45 
polyvinylidene fluoride 
55 55 55 55 
copolymer I -- -- -- 43 
copolymer II 43 -- -- -- 
triblock copolymer 
14.5 -- 14.5 
-- 
Properties 
Tensile strength at 
37 26 26 40 
fracture (MPa) 
Elongation at fracture 
161 5 8 113 
(%) 
IZOD notch impact 
136 34 54 15 
value (J/m) 
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It may be seen from the properties as recorded in Table A that the addition 
of copolymer I to a mixture of a polyphenylene ether and a polyvinylidene 
fluoride leads to an increase of the tensile strength and of the 
elongation: the notch impact value, however, deteriorates (comparative 
examples A and C). The addition of a triblock copolymer (comparative 
example B) leads to a small improvement of the notch impact value, while 
the tensile strength and the elongation remain approximately the same. 
As a result of the addition of a triblock copolymer and a copolymer (see 
example I) the tensile strength and the elongation become larger, while in 
addition the notch impact value is increased to a much stronger extent 
than would be expected on the basis of comparative example B.