Note: Descriptions are shown in the official language in which they were submitted.
t'~ t~ 3 1, _i f~
O.Z. 0050/41887
Hiqh impact thermoplastic moldinq compositions
The present inver.tion relates to thermoplastic
molding compositions comprising polyphenylene ethers,
impact modified polystyrene and a block copolymer of
styrene and a diene. Such molding compositions are des-
cribed for example in the following references (1)
to (7):
~1) DE 20 00 118
(2) DE 22 55 930
(3) DE 27 50 514
(4) J5 9140-257
(5) EP 52 854
(6) EP 83 049
(7) DE 25 06 094.
Polymer mixtures which contain polyphenylene
ethers and block rubbers of aromatic vinyl compounds and
dienes are disclosed for example in (1) and (2). The
disadvantage of the molding compositions is a lack of
thermal stability. Moreover, ready-produced articles
which contain higher proportions of hydrogenated block
rubber show signs of delamination; that is, long flow
paths give rise to inhomogeneous layer structures.
Reference (3) describes an impact resistant
thermoplastic composition which in addition to a poly-
phenylene ether and high impact polystyrene contains amixture of an olefinic resin (e.g. EP) and a linear or
radial block copolymer of an aromatic vinyl compound and
a diene. However, the molding compositions have the
disadvantage that the multiaxial toughness is
insufficient.
Reference (4) describes an impact resistant
polyphenylene ether resin composition which in addition
to a polyphenylene ether and high impact polystyrene
contains a two-block copolymer of an aromatic monovinyl
compound and an olefinic block and also a styrene-grafted
ethylene-propylene ~opolymer. Again these molding
- 2 - O.Z. 0050/41887
compositions have the disadvantage of delam.ination in
processing.
References (5), (6~ ancl (7) describe mixtures of
polyphenylene ethers and high impact polystyrene which
contain a styrene-grafted EPDM rubber as essential
component. Once again, if the proportion of EPDM rubber
is high, the ready-produced article is found to be prone
to delamination. Also, the multiaxial toughness is
inadequate.
It has now been found that molding compositions
which are based on blends of polyphenylene ethers (PPEs~
and high impact polystyrene (~IPSJ and additionally
contain a block copolymer of styrene and a diene and also
a styrene-modified ethylene-~-olefin polyene terpolymer
have excellent properties. Of note is the high impact
strength and the multiaxial toughness at low tempera-
tures~ as well as the excellent weather resistance and
thermooxidation resistance coupled with good heat resis-
tance and good flowability. The molding compositions can
be processed into test specimens which are free of
delamination.
Accordingly, the present invention provides a
molding composition comprising - based on the sum total
of A, B, C and D -
A: not less than 5, preferably 20-80, % by weight of a
polyphenylene ether A
B: not less than 5, preferably 20-80, % by weight of an
impact modified polystyrene B
C: 1 - 20, preferably 3-15, % by weight of a block
copolymer C of styrene and a conjugatPd diene
D: 1 - 20, preferably 3-15, % by weight of a copolymer
D obtained by grafting styrene onto an EPDM rubberO
There now follow specific remarks concerning the
constituents of the molding composition of the present
invention~
Component A:
The likely polyphenylene etherq A are known per
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se and are preferably prepared by oxidative coupling of
phenols which are disubstituted ~n the o-position.
Examples of s~lbstituent:s are halogen atoms such
as chlorine or bromine and alkyl groups of from 1 to
4 carbon atoms which preferably have no ~-disposed
tertiary hydrogen atom, e.gO methyl, ethyl, propyl and
butyl. The alkyl groups may in turn ~e substituted by
halogen such as chlorine or bromine or by hydroxyl.
Further examples of possible substituents are alkoYy,
preferably of up to 4 carbon atoms, and phenyl which may
be suhstituted by halogen and/or alkyl. It is also
possible to use copolymers of various phenols, such as
copolymers of 2,6-~imethylphenol and 2,3,6-trimethyl-
phenol. It is of course also possible to use mixture of
various polyphenylene ethers.
Preference is given to those polyphenylene ethers
which are compatible with, i.e. wholly or substantially
soluble in, aromatic vinyl polymers (cf. A. Noshay r ~lock
Copolymers, pages 8 to 10, Academic Press~ 1977, and
20 O. Olabisil Polymer-Polymer Miscibility, 1979,
pages 117-189).
Examples of polyphenylene ethers are
poly(2,6-dilauryl-1,4-phenylene ether),
poly(2,6-diphenyl-1,4-phenylene ether),
poly(2,6-dimethoxy-1,4-phenylene ether),
poly(2,6-diethoxy-1,4~phenylene ether),
poly(2-methoxy-6-ethoxy-1,4-phenylene ether),
poly(2-ethyl-6-stearyloxy-1,4-phenylene ether),
poly(2,6-dichloro-1,4-phenylene ether),
poly(2-methyl-6-phenylene-1,4-phenylene ether~,
poly(2,6-dibenzyl-1,4-phenylene ether),
poly~2-ethoxy-1/4-phenylene ether),
poly(2-chloro-1,4-phenylene ether),
poly~2,5-dibromu-1,4-phenylene ether).
Preference is given to using polyphenylene ethers
where the substituents are alkyl groups of from 1 to
4 carbon atoms, such as
- 4 - O.Z. 0050/41887
poly(2,6-dimethyl-1,4-phenylene ether),
poly(2,6-diethyl-1,4-phenylene ether),
poly(2-methyl-6-ethyl-1,4-phenylene ether),
poly(2-methyl-5-propyl-1,4-phenylene ether),
poly(2,6-dipropyl-1,4-phenylene ether) and
poly(2-ethyl-6-propyl-1,4-phenylene ether)~
It is also possible ~o use graft copolymers of
polyphenylene ethers and aromatic vinyl polymers such as
styrene, ~-methylstyrene, vinyltoluene and chlorostyrene.
Suitable polyphenylene ethers generally have an
intrinsic vlscosity ~5p/C of 0.2-0~7 dl/g, measured in
chloroform at 25Co This corresponds approximately to the
molecular ~eight range 10,000-60,000.
The molding compositions of the pre~ent invention
are preferably based on poly~2,6-dimethyl-1,4-phenylene
ether).
Component B.
Component B in the molding material according to
the invention is impact resistant polystyrene resin,
which, for the purposes of the present invention, is two-
phase impact resistant polystyrene built up from a hard
matrix and a soft phase. This polystyrene is generally
known.
The hard matrix of component B comprises a
styrene polymer and makes up :Erom 60 to 95 % by ~eight,
preferably 80 to 95 % by weight, based on component A. A
suitable monomer for the hard matrix is, in particular,
styrene or p-methylstyrene or mixtures of substituted
styrenes, but the exclusive use of styrene is preferredf
and the hard matrix thus preferably consists of poly-
styrene.
The hard matrix is produced in a conventional
manner during the preparation of component B by
polymerizing, thermally or by means of free radicals, a
soft phase, ieO a rubber, together with the styrene
monomer later making up the hard matrix, to form graft
copolymers of the rubber ~soft phase) and ungrafted
?
- 5 - O.Zq 0050/41887
styrene polymers, the hard matrix.
The soft phase is t:hus a graft copolymer
comprising the monomer~s) of the resin matrix, ie. in
particular styrene~ on a rubber or on a mixture of
rubbers.
The hard matrix can have a viscosity number ySp/c
in the range from 50 to 140, in paxticular in the range
from 70 to 120. This corresponds to mean molecular
weights (Mw) in the range from 100,000 to 350,000, in
particular from 150,000 to 300,000.
In the end, the soft phase is finely dispersed in
the hard matrix. The way in which a soft phase can be
dispersed in a hard matrix is known. The soft phase is
present in the hard m~trix in a proportion of from 3 to
40 % by weight, preferably from 5 to 20 % by weight, and
has a mean particle size in the range from 0.01 to 10 ~m,
preferably in the range from 0.3 to 8 ~m. The particle
size range mentioned is the mean particle size determined
by counting the nu~ber of particles shown in an electron
photomicrograph, ie~ a number average. The weight average
particle size of the soft component should be within the
range from 0.2 to 6 ~m. This weight average particle size
is to be understood as defined in DE-A-30 35 643. Of
particular suitability are impact modified polymers where
the weight average particle size is within the range from
0.5 to 4 ~m. The particles can he cellular or capsule
particles. Such particles are described for example in A.
Echte, Styrolpolymere, Winnacker-Kuchler, Chemische
Technologie, Volume 6l Organische Technologie II, Carl
Hanaer Verlag, Munich-Vienna 1982, pp. 373-3~0.
The preferred soft phase is polybutadiene and the
graft copolymer thereof with styrene. Polybutadi nes of
the medium- or high-cis type having molecular weights in
the range from 70,000 to 450,000 (weight average~ are
particularly suitable. Medium-cis polybutadienes having
molecular weights of from 300,000 to 400,000 are
preferred~
- 6 - O.Z. 0050/41887
- The impact-resistant styrene polymer is prepared
in bulk, solution or suspension in a conventional manner
(cf. Ullmanns Encyclopadie der Technischen Chemie, volume
19, pages 265-272, Verlag ('hemie, WeinheLm 1980).
Possible comonomers for preparing copolymers are for
example (meth)a~rylic acid, (meth)acrylic esters having
from 1 to 4 carbon atoms in the alkyl moiety,
acrylonitrile and maleic anhydride and also maleimides.
The level of comonomer in the styrene polymer varies with
the structure of the comonomer. The decisive determinant
for the level of comonomer in the copolymer is the
miscibility of the copolymer with the polyphenylene
ether. Sl-ch miscibility limits are known and described
for example in U5 ~atents 4,360,618 and 4,405,753 and in
J.R. Fried, G.A. Hann, Polymer Eng. Sci., 22 (1982j, 705.
~he copolymers are prepared for example as described in
Ullmanns Encyklopadie der techn. Chemie, volume 19, pages
27~ ff, Verlag Chemie, Weinheim (1980). The copolymers
generally have weight average molecular weights (M~) of
from 10,000 to 300,000, which can be determined in a
conventional manner~
The most commonly employed methods for preparing
impact modified styrene polymers are bulk or solution
polymerization in the presence of a rubber, as described
for example in US Patent 2,694,692, and bulk suspension
polymerization as described for example in
US Patent 2,862,906.
The rubbers used are the natural or synthetic
rubbers which are customarily used for the impact modifi-
cation of styrene polymers. Suitable rubbers for the
purposes of the present invention, besides natural
rubber, are for example polybutadiene, polyisoprene and
copolymers of butadiene and/or isoprene with styrene and
other comonomers which have a glass transition tempera~
ture, determined in accordance with R.H. Illers and
H. Breuer, ~olloidzeitschrift 190 ~1963), 16-34 (1), of
below -20C. However, it is also possible to use
- 7 - O.Z. 0050/418~7
acrylate, ~PDM, polybutylene and polyoctenamer rubbers.
Component C
The block copolymers used according to the
invention are elas-tomeric copolymers of the type AB, ABA'
or (A/B)~-X, where A and A' are each a non-elastomeric
polystyrene block and B is an elastomeric hydrogenated
and/or non-hydrogenated block of a conjugated diene, n is
an integer of at least 3, and X is the radical of a
multifunctional coupling agent via which the branchings
(A-B) of the block copolymer are chemically bonded
together.
These compounds are known per se from
EP-A-95 098.
Instead of styrene it is possible to use side
chain alkylated styrene, such as ~-methylstyrene, and
ring substituted styrene, such as vinyltoluene, ethyl-
vinylbenzene and others. Preference is given to using
styrene alone.
Conjugated dienes which are particularly suitable
for forming the polymers of the present invention are for
example 1,3-butadiene and isoprene. In the preparation of
block copolymers these dienes are used either alone or
mixed with one another.
Preference is given to a non-hydrogenated block
copolymer, particularly to a non-hydrogenated ABA' three-
block copolymer whose end blocks have a molecular weight
within the range of about 2,000 - 100,000 while the
central block has molecular weight within the range from
about 25,000 to about 100,000, the molecular weight of
the central block being greater than that of the combined
end ~locks.
The block copolymers are prepared for example
using an organometallic initiator based on sodium or
lithium or an organic derivative thereof. The initiator
may be monofunctional or difunctional.
The block copolymers are present in the molding
compositicn of the present invention in a weight
- 8 - O.Z. 0050/41887
proportion of from 1 to 20 %, preferably from 3 to 15 %.
Component D
This co~ponent is a styrene-grafted ethylene/~-
olefin/polyene terpolymer. Preferred ~-olefin~ contain
from 3 to 10 carbon atoms, for example propylene,
l-butene, l-pentene, l-hexene and 1-heptene~ Propylene is
preferredO The polyenes used are preferably cyclic or
open-chain non-conjugated compounds. Examples are
1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene,
6-methyl-1,5-heptadlene, 7-methyl-1,~-octadiene,
11-ethyl-1,11-tridecadiene,9-ethyl-1,9-undecadiene,iso-
prene, 1,4-pentadiene, 1,3-pentadiene, 1,4,9-decatriene,
1-phenyl-1,3-butadiene, p-diallylbenzene, 4-vinyl-1-
cyclohexene, 1,3,5-trivinylcyclohexane, trans-1/2-
divinylcyclohexane, 1,5-cyclooctadiene, 1,3,5-cyclo-
heptatriene, 1,5,9-cyclododecatriene, 1,4-cyclo-
heptadiene, cyclopentadiene, 2,2'-dicyclopentenyl-1,~-
bis(cyclopenten-2-yl)butane, 4,7,8,9-tetrahydroindene,
bicyclo[3,3,03octadiene-2,6-dicyclopentadiene, 2-methyl-
2,5-norbornadiene, 5-methylene-2-norbornene,
5-ethylidene-2-norbornen~, 5-isopropylidene-2~norbornene,
5-isopropenyl-2-norbornene, 5-(2'-methyl-1'-propenyl)-2-
norbornene, 5-(1',2'-dimethyl-1'-propenyl)-2-norbornene,
5-(2'-butenylj-2-norbornene, 6-methyl-5-(2'-butenyl)-2-
norbornene, 6-(3'-cyclohexenyl)-2-norbornene, tricyclo-
pentadieneand6-chloromethyl-5-isopropenyl-2-norbornene.
The grafting base comprises at least 10 % by
weight of ethylene, about 10 - 90 % by weight of ~-olefin
and 0.1 - 30 % by weight of polyene. Preference is given
to at least 40 % by weight of ethylene, 10 - 60 % by
weight of ~-olefin and 0.3 - 10 % by weight of polyene.
Particular preference is given to 50 - 85 % by weight of
ethylene, 15 - 50 % by weight of ~-olefin and 1 - 7 % by
weight of polyene~
Possible grafting agents are all the above-
mentioned styrenes. Styrene itself is preferred.
To graft the EPDM rubber it is possible to use
- 9 O.Z. 0050/41887
any customary polymerization technique, such a~ suspen-
sion polymerization, emulsion polymerization, solution
polymerization or bulk polymerization. Preference is
given to emulsion polymerization. The styrene content of
the end product is for example 5 - 70 ~ by weight~
preferably 5 - 50 ~ by weight, particularly preferably
5 - 30 ~ by weight.
Examples of the preparation of Component D may be
found for example in EP-A-83 049 and EP-A-52 854.
Component D is present in the molding composition
of the present invention in an amount of from 1 to 20 %
by weight, preferably 3 - 15 % by weight.
Component E
Further additives for possible inclusion in the
molding composition of the present invention are cus-
tomary, in general mineral, reinforcing materials, such
as glass ~alls, mineral fibers, whiskers, mica or in
particular glass fibers in amounts of for example up to
30 % by weight, based on 100 % by weight of the sum total
of the constituents of the molding composition.
Additionally~ yet further additives, such as
flameproofing agents, heat and light stabilizers, lubri-
cants, demolding agents and colorants such as dyes and
pigments, may be present in customary amounts. The
flameproofing agents used are preferably phosphorus-
containing compounds, such as phosphine oxides or
phosphates.
Preparation of molding compositions
The thermoplastic molding compositions of the
present invention are advantageously prepared by mixing
the components at 200-350C, preferably 250-300C, in
customary mixing apparatus, for example kneaders, Banbury
mixers and single-screw extruders, preferably in a twin-
screw extruder. To obtain a homogeneous molding com-
position, intensive mixing is necessary. The residencetime is generally within the range from 0.5 to 30 min.,
preferably from 1 to 5 min. The order of mixing the
- 10 ~ O.Z. 0050/41887
components may be varied: selected components may be
premixed or else all the components may be mixed
together.
The molding compositions of the present invention
are highly suitable for producing moldings of any kind,
for example by injection or extrusion molding. They can
also be used for producing films and sheetware by thermo-
forming or blow molding.
The molding compositions of the present invention
are noteworthy in particular for very good toughness
combined with high heat resistance and good flowability.
Of special significance is the good weathering and
thermooxidation resistance and the excellent appearance
of the articles molded therefrom, which show no sign of
delamination.
To illustrate the advantages of the molding
compositions, the following properties are determined:
the melt flow index (MFI3 at 250C and under
21.6 kg in accordance with German standard specification
DIN 53735; the Vicat temperature VST/B in accordance with
German standard specification DIN 53460; the notched
impact strength a~ in accordance with German standard
specification DIN 53453; and the penetration energy DSTA
in accordance with German standard specification
DIN 53443 at 20C and -40C.
The thermooxidation resistance was tested in
terms of a penetration test. To this end, the penetration
energy was measured on specimens which had been stored at
110C for 7 and 14 days respectively. The specimens were
stored ~or this purpose in a ~eraeus through-circulation
cabinet model UT 6200.
The delamination tendency was determined by
examining the appearance of the fracture site of Roundels
using the penetration test and by examining moldings
after cross-hatching.
The sp~cimens were injection molded at 2aooc.
The operati~e and comparative examples were
~ O.~. 0050/41887
conducted using the following components:
Component A:
A(1): poly(2,6-dimethyl-1,4-phenylene ether) having a
limiting viscosity of 0.50 dl/g measured in chloroform
Component B:
B(1): high impact polystyxene 586 from BASF AG
containing 10 % by weight of butadiene.
Component C:
C(l) SBS three-block rubber Cariflex TR 1101 from
Shell AG.
Component D:
D(1): 40 g of an EPDM polymer (Vistalon 7000 from
EXXON) were introduced into a 500 ccm glass autoclave
together with 200 ccm of water. To this were added in
succession with stirring a solution of 0.2 g of benzoyl
peroxide in 40 g of styrene and a solution of 1.2 g of
polyvinyl alcohol in 40 g of water. The mixture was first
stirred for one hour then left to stand at 90C for
6 hours and finally at 115C for 2 hours. The product was
isolated by filtration and dried under reduced pressure
(for producing molding compositions of the present
invention).
D(2): styrene-modified EPDM polymer as per Example 8 of
EP 52 854 (for producing molding compositions of the
present invention).
D(3): Vistalon 7000 from Exxon (for comparison).
The operative and comparative examples are listed
in Table 1 and the properties of the corresponding
molding compositions in Table 2.
- 12 -- O.Z. 0050/41887
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