Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Thermopl_as~ic molding materials
The present invention relates to thermoplastic
molding materials which are based on polyphenylene ethers
and styrene/acrylic acid copolymers and may or may not
have been toughened.
9lends of polyphenylene ethers and styrene poly-
mers are known, and form the subject of a number of
patents. The relevant prior art includes (1) U.S. Patent
3,383,435, (2) German La;d-Open Application DO~ 2,713,43
and (3) U.S. Patent 4,300,618.
(1) describes compositions comprising polyphenyl-
ene ethers and styrene resins. Either the latter can be
modified with rubber, generally polybutadiene, or pure
polystyrene can be used. However, the heat resistance and
the mechanical properties of these blends, and their
resistance to chemicals, frequently do not meet the
requirements set.
If the styrene resin in ~1) is replaced by sty
_ rene/maleic anhydride copoLymers tS-MAA), as descr;bed in
(2), the heat distortion resistance of the blends~ and
their resistance to chem;calsr can be improved, but the
mechanical properties of the blends obtained are unsatis-
factory, even when rubber-modified S-MAA copolymers are
used.
(3) describes blends of polyphenylene ethers and
styrene/acrylonitrile copolymers which possess high rigi-
dity and ;mproved resistance to chemicals. However, the
; toughness and the heat distortion resistance are still not
completely satisfactory.
It is an object of the present invention to pro-
vide thermoplastic molding materials which are based on
blends of polyphenylene ethers and styrene polymers and
which possess appropriately high heat distortion resis-
tance, good resistance to chemicals and well balanced mech-
anical properties.
We have found that this object is achieved by m0ld-
;ny mater;als which contain a mixture of
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(I) from 95 to 5% by weight of a polyphenylene ether and
tII) from 5 to 95% by weiyht of a copolymer consisting of
A1) from 73 to 99 parts by we;ght of a monovinyl-
aromatic compound,
A2) from 1 to ~2 parts by weight of (meth)acrylic
acid, and
B) from 0 to 20 parts by weight of an elastomer
component which has a glass transition tempera-
ture of ~ 0C, ~he sum of the number of parts
by we;ght being 100.
The components of the novel molding material,
their preparat;on~ and the preparation of the molding
material are described below.
Component I
Component I of the novel molding material compri-
ses one or more resins which are composed of a polyphenyl-
ene ether tPPE) and are present in amounts of from 95 to
5, preferably from 70 to 30, % by weight, based on the
mixture of I and II.
The polyethers are compounds which are based on
polyphenylene oxides disubstituted ;n the ortho-position,
the ether oxygen of one unit being bonded to the benzene
nucleus of the adjacent unit. Not less than 50 un;ts
should be bonded to one another in this way. The poly-
ethers can carry, ;n the ortho-pos;t;on to the oxygen,
hydrogen, halogen, a hydrocarbon radical which does not
possess a tert;ary X-hydrogen atom, a halohydrocarbon,
phenyl or a hydrocarbon-oxy radical. Examples are poly-
(2,6-dichloro-1,4~phenylene) ether, poly(2,6-diphenyl-1,4-
phenylene) ether, poly(2,6-dimethoxy-1,4 phenylene) ether,
polyt2,6-d;methyl-1,4-phenylene~ ether and poly(2,6-di-
bromo-1,4-phenylene) ether. Poly(2,6-dimethyl-1,4-phenyl-
ene) ethers are preferably employed, those having a limit-
;ng v;scosity of from 0.45 to 0.65 dl/g tmeasured in
chloroform at 30C) being particularly preferred.
The polyphenylene ethers can be prepared from the
phenols ~n a conventional manner, for example in the
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567
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presence of a complex~forming agent, such as copper bro-
mide or sec.-dibutylamine.
Component II
Component Il of the noyel molding materials com-
prises one or more styrene/(meth)acrylic acid copolymerswhich may or may not have been toughened. It consists of
the monomers A1) and A2) and, i~ it has been toughened,
of the elastomer component B.
The novel molding materials contain component II
;n an amount of from 5 to 95, preferably From 30 to 70~
% by weight based on the amounts o~ components I and II.
Su;table monovinyl-aromatic monomers A1) are
styrene, ~-methylstyrene and styrenes of not more than
12 carbon atoms which are alkylated in the nucleus, par-
ticularly preferably styrene, o~-methylstyrene and p-
methylstyrene.
Acrylic acid and/or methacrylic acid are used as
the monomers A2). Component II contains from 78 to 99,
preferably from 91 to 99, parts by weight of monomer A1)
and from 1 to 12, preferably from 1 to 9, parts by weight
of monomer A2), the sum of the number of parts by weight
be;ng 100, unless component 8 is present.
Constituent A of component I is prepared by con-
tinuous copolymerization of the monomers A1) and A2) at
elevated temperatures, while stirring vigorously. The
monomers A1~ and Az) are introduced continuously into
a polymerization vessel, and an amount of polymerization
mixture equivalent to these amounts is simultaneously
removed from ~he vessel (cf. A. W. Hanson and R. L.
3û Zimmermann, Industrial Eng. Chemistry 49 ~1957), 803).
However, constituent A can also be prepared by any
other conventional polymeriza~ion method.
Constituent B
Constituent B is an elastomer component which may
or may not be present in the novel molding materials. It
is a graft polymer which is used in an amount of from û
to 2û, in particular from 1 to 18, parts by we;ght, the
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l'` ~
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sum of the number of parts by ~eight of a~ A1) and A
being 10U~
This graft copolymer consists of from 10 to 50,
preferably from 15 to 45, parts by weight of a mix~ure of
one or more v;nyl-aromatic monomers of not more than 12
carbon atoms, and from û.1 to Z5, preferably from 5 to 20,
parts by weight of one or more tmeth~acrylates andJor
acrylonitrile and/or (meth)acrylic acid and/or maleic an-
hydride as a grafted shell, on 50 - 90, in part;cular
60 - ~0, parts by weight of an elastomeric graftin~ base
(rubber component).
This rubber component should have a glass transi-
tion temperature (according to K~ H. Illers and H. ~reuer,
Kolloid-Zeitschrift 176 ~19~1), 110) of below 0C. Exam-
ples of suitab`le rubbers are polybutadiene (cf~ GermanLaid-Open Applications DOS 1,420,775 and DOS 1,495~089),
copolymers of butadiene and styrene (cf. British Patent
649,166), copolymers of butadiene and styrene and poly-
acrylates which may or may not be crosslinked (cf. German
Publ;shed Applica~ions DAS 1~138r921, DAS 1,2~4,4~ and
DAS 1,260,135), copolymers of acrylates and butadiene
(cf. German Published Application DAS 1,238,2~7), elasto-
mers of copolymers of acrylates w;th styrene, acrylonit-
rile and vinyl ethers and copolymers of ethylene with a
non-conjugated diene tEPDM rubber), and hydrogenated sty-
rene~butadiene rubber polymers.
The vinyl-aromatic graft monomers are styrene,
~ -methylstyrene and/or styrenes of not more than 12 car-
bon atoms which are alkylated in the nucleus; suitable
polar monomers are acrylates and methacrylates of alkanols
of not more than 8 carbon atoms, acrylonitrile, acrylic
acid, methacrylic acid and maleic anhydride, and mixtures
of these.
The preparation of the elastomer components B is
kno~n per se~ They can be prepared by, for example, poly-
merization of a mixture of styrene and acrylic acid or
tmeth)acrylates in the presence of a rubber. The graft
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copolymerization can be carried out in a conventional
manner, in solution, in suspension or, preferably, in emul-
sion. It is essential fcr success that the constituents
- A and B of component II of the novel rnolding material
have a composition, and are matched up with one another
in the mixture, so that the absolute amounts of the polar
monomers in constituents A and B differ by less than 9.
Component II of the noveL mo~ding materials is
preferably obtained by mixing melts of constituents A and
B. To do this, constituents A and a, in the form of metts,
are mixed at from Z~0 to 260C in an extruder, a roll
mill or a kneader, the residence time being a few minutes.
However, it is also possible to m;x solutions of consti-
tuent A and of the graft copolymer B, and then to vola-
tilize the solvents~
In addition to containing components I and II,the novel molding material can~ if required, contain
effective amounts of conventional additives. Examples of
_ such additives are pigments, dyes, ~illers, flameproofing
agents, such as triaryl phosphates, other compatible poly-
mers, antistatic agents, antioxidants and lubricants.
Preparation of the novel molding materials from components
I and II
The molding material according to the invention
can be prepared from components I and II as described
below. However, the molding material is preferably pre-
pared from constituents A and 8 and component I, w;th or
without other additives, by mixing the so~t and hard con-
stituents (of component II) and the polyphenylene ethers.
The preparation is usually carried out in an apparatus
which permits homogeneous mixing, eg. a kneader~ an extru-
der or a roll mill.
However, it is also possible to prepare the novel
molding material by thoroughly mixing solutions of the indi-
vidual components and then evaporating the solvent mixture.Combined processes in which solutions and melts are mixed,
for example in a devolatilization extruder, have also been
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successfully tested.
The copolymers A1 to A3 listed in Table 1, and
where relevant the graft rubbers B1 to a~ stated in
Table 2, ~ere used for the preparation of the novel mold-
ing materials~ Composition and other properties are shownin the stated tables.
A commercial product based on poly(2,6-dimethyl-
1,4-phenylene) ether and having a limiting viscosity of
û.5 Cdl/g~ and a notched impact strength of 4 (kJ/m)
was used as component I.
TA8LE 1
SAS copolymers (constituent A)
Name Composition in Notched impactVicat
parts by weight strengthtemperature
S AS (kJ/m2) (C)
A1 95 5 3 101
A2 92 8 3 101
A3 35 15 3 103
S = styrene, AS = acrylic acid
The copolymers A1 to A3 all had a viscosity
number of 70 (ml/g), measured on a 0.5% strength soLution
in dimethylformamide at 25C.
TABLE 2
Graft copolymers (constituent B)5 Name Composition of Composition of the Glass transi-
the rubber ~%) grafted shell (~) tion tempera-
Bu BA S AS AN ture (C)
~1 100 ~ 90 10 -81
B2 ~ 100 90 10 - -46
30 B3 S0 50 85 10 5 -S7
Bu = butadiene,
BA = butyl acrylate~
S = styrene,
AS ~ acrylic acid and5 AN = acrylonitrile.
Triphenyl phosphate was employed as component III.
The parameters stated in the experiments and com-
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parative experiments were deterrnined as follows:
1~ The impact strength and notched impact strength in
(kJ/m2) were measured according to DIN 53,453, at a
material tempera-ture of 250C, on in~ectio~ molded
standard small bars.
Z. The modulus of elasticity in (N/mm2) was determined
according to DIN 53~457, on injection molded dumbbell
test pieces.
3. a) The viscosity numbers, VZ, in (ml/g) were deter-
m;ned for a 0.5% strength solut;on ;n d;methylfor-
mamide.
b) The limiting viscosity ~ sp/c in ~cm3/g) ~as meas-
ured ;n CHCl3 at 30C.
4. The Vicat softening point in C was determined accord-
;ng to DIN 53,460, method B, ;n sil;cone oil.
5. The glass trans;t;on temperatures of the rubbers were
determined in accordance with K. ~. Illers and H. Breuer,
; Kolloid-Zeitschr;ft, loc~ c;t.
_ 6. The resistance to chemicals was checked and visually
assessed in a short-time test with injection molded
boxes which were filled with isopropanol and stored for
48 hours.
Rating:
1 = no change
2 = roughening of surface, cloudiness
3 = deformation
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