Thermoplastic moulded materials based on polycarbonates and...

Details Thermoplastic moulded materials based on polycarbonates and... Thermoplastic moulded materials based on polycarbonates and...

1998-11-23

2001-01-16

Buttner, David J. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S133000, C525S148000

Reexamination Certificate

active

06174958

ABSTRACT:

The present invention relates to thermoplastic molding materials based on polycarbonates and styrene/acrylonitrile polymers, which contain alkyl(meth)acrylate-based copolymers for improving their properties.
Thermoplastic blends of polycarbonates, elastomeric graft copolymers and styrene copolymers are known as PC/ABS or PC/ASA blends and, owing to their property profile, are used in a wide variety of areas, for example as high-strength shaped articles in automotive construction or for household appliances, electrical appliances or office machines. Such molding materials may be modified according to requirements. German Laid-Open Application 4,211,061 discloses polymer blends of this type which contain polyamides as a further polymeric component. Such polymer blends may also be flameproofed (cf. German Laid-Open Application 4,034,336).
In order to achieve a balanced property profile, further polymer-based additives may be added to these blends. However, this may have an adverse effect on individual properties of the desired property profile. For example, there is a danger of partial mutual incompatibility of the polymers, resulting in a loss of toughness. Moreover, poorer processing stability or reduced heat resistance may result.
EP-A-135 492 describes ABS/PC blends with terpolymers based on styrene/maleic anhydride (S/MAA), which contain a minor amount of C
1
-C
3
-alkyl methacrylates as polymerized units. These blends have better impact strength than blends which contain S/MAA copolymers. However, blends having a high MAA content tend to exhibit surface defects under unfavorable processing conditions. EP-A-135 493 describes similar polymer blends to which 1-30% by weight of a polyether/polyester block copolymer are added.
EP-A 455 116 describes polymer blends which contain from 50 to 90% by weight of polymethyl methacrylates, from 5 to 40% by weight of copolymers containing butadiene as a component of the tough phase and from 5 to 40% by weight of polycarbonates. The polycarbonate content improves the toughness and the heat distortion resistance compared with pure polymethacrylate/rubber blends.
German Laid-Open Application DE-OS 3,325,702 describes polycarbonate/rubber blends to which from 0.1 to 15% by weight of a low molecular weight polymer having acidic groups have been added in order to improve the impact strength.
EP-A 210 510 describes thermoplastic molding materials containing from 20 to 80% by weight of a thermoplastic polycarbonate, from 10 to 60% by weight of at least one graft rubber and from 10 to 70% by weight of a copolymer of the SAN type which has a low limiting viscosity (2-10 ml/g). This improves the flowability of the thermoplastic molding materials.
German Laid-Open Application DE-OS 3,514,185 describes thermoplastic molding materials which comprise from 20 to 80% by weight of a polycarbonate, from 10 to 60% by weight of graft rubbers and from 10 to 70% by weight of at least two different copolymers of the SAN type, one of which contains methyl methacrylate as the main component. The materials have good toughness, heat stability and heat distortion resistance. However, nothing is said about the processing stability.
It is an object of the present invention to provide thermoplastic molding materials based on polycarbonates, elastomeric graft copolymers and styrene/acrylonitrile copolymers, which have better processing stability without other properties, for example toughness, being adversely affected.
We have found that this object is achieved and that, surprisingly, molding materials which contain a relatively small amount of a copolymer comprising e
1
) alkyl methacrylates, e
2
) maleic acid or maleic anhydride, fumaric acid or maleimide and e
3
) vinylaromatics (component E) and, if required, a polymeric, OH-containing compound (component F) in addition to polycarbonates (component A), elastomeric graft copolymers (component B) and thermoplastic copolymers based on styrene/acrylonitrile (components C+D) are distinguished by better mechanical properties and higher processing stability than molding materials without the additives E and F.
The present invention therefore relates to thermoplastic molding materials containing, as essential components
A) from 10 to 90.9% by weight of at least one aromatic polycarbonate,
B) from 5 to 30% by weight of at least one graft copolymer which is composed of
b
1
) from 20 to 80% by weight of a grafting base of at least one elastomeric polymer having a glass transition temperature below 0° C. and
b
2
) from 20 to 80% by weight of a graft layer which has a glass transition temperature above 50° C. and is composed of two monomers b
21
) and b
22
),
C) from 2 to 70% by weight of at least one thermoplastic copolymer of
c
1
) from 50 to 90% by weight of styrene and
c
2
) from 10 to 50% by weight of acrylonitrile, C
1
-C
8
-alkyl (meth)acrylate or a mixture thereof,
 having a glass transition temperature above 50° C. and a viscosity number of from 40 to 160 cm
3
/g,
D) from 2 to 70% by weight of a thermoplastic copolymer which differs from the copolymer C) and contains, as polymerized units,
d
1
) from 50 to 99% by weight of styrene, substituted styrenes of the general formula I
 where R is C
1
-C
8
-alkyl or hydrogen, R′ is C
1
-C
8
-alkyl and n is 0, 1, 2 or 3,
 or a mixture thereof and
d
2
) from 1 to 50% by weight of acrylonitrile, methacrylonitrile, maleic anhydride, maleimide, which may have a C
1
-C
8
-alkyl group or C
6
-C
20
-aryl group on the nitrogen atom, C
1
-C
8
-alkyl (meth)acrylate, (meth)acrylamide, C
1
-C
8
-alkyl vinyl ether or a mixture thereof,
E) from 0.1 to 25% by weight of at least one copolymer, composed of
e
1
) from 50 to 99% by weight of a mixture of
e
11
) from 80 to 100% by weight of at least one C
1
-C
10
-alkyl methacrylate and/or C
5
-C
8
-cycloalkyl methacrylate and
e
12
) up to 20% by weight of at least one C
1
-C
10
-alkyl acrylate,
e
2
) from 0.5 to 20% by weight of maleic acid, maleic anhydride, fumaric acid, itaconic acid or maleimide, which may have a C
1
-C
8
-alkyl group or C
6
-C
20
-aryl group on the nitrogen atom, or a mixture thereof and
e
3
) from 0.5 to 40% by weight of at least one vinylaromatic which is unsubstituted or substituted on the aromatic nucleus by one or two C
1
-C
4
-alkyl radicals,
F) from 0 to 12.5% by weight of at least one polymeric, OH-containing compound and
G) from 0 to 50% by weight of additives, assistants and/or fibrous or particulate fillers or a mixture thereof,
the amounts by weight of the components E and F together accounting for not more than 25% by weight and the amounts by weight of the components A to G summing to 100% by weight.
The present invention furthermore relates to the use of these thermoplastic molding materials for the production of moldings, including fibers and films, and the moldings, semifinished products or films obtainable from the thermoplastic molding materials.
C
1
-C
8
-alkyl and C
1
-C
10
-alkyl groups are understood below as meaning linear or branched, preferably linear, alkyl groups. They are in particular C
1
-C
6
-alkyl. Examples of alkyl are methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, n-hexyl and 2-ethylhexyl. Examples of C
1
-C
6
-alkylene and C
2
-C
6
-alkylidene are methylene, ethylene, ethylidene, 1-methylethylene, 1,3-propylene, 1,1-propylidene, 2,2-propylidene, 2-methylpropylidene, n-butylene, 2-methylbutylene, 1,1-butylidene, 2,2-butylidene, 1,1-pentylidene, 2,2-pentylidene and 3,3-pentylidene. C
3
-C
10
-Cycloalkyl is to be understood as meaning cycloalkyl which may carry one or more C
1
-C
4
-alkyl groups as substituents. Examples of these are cyclopropyl, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl and trimethylcyclohexyl. Examples of C
3
-C
10
-cycloalkylene and C
3
-C
10
-cycloalkylidene are 1,1- and 1,2-cyclopropylene, 1,1-, 1,2- and 1,3-cyclobutylene, 1,1-, 1,2- and 1,3-cyclopentylene, 1,1-, 1,2-, 1,3- and 1,4-cyclohexylene and the methyl- or ethyl-substituted derivatives thereof, for example 2,2

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