Polycarbonate moulding materials

Details Polycarbonate moulding materials Polycarbonate moulding materials

2000-05-31

2002-07-23

Buttner, David J. (Department: 1712)

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

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S296000, C524S298000, C524S320000, C524S321000, C524S322000, C525S067000, C525S133000, C525S146000, C525S148000

Reexamination Certificate

active

06423767

ABSTRACT:

The present invention relates to molding compositions which contain
A) at least one polycarbonate,
B) at least one graft polymer based on an elastomer having a glass transition point below 10° C.,
C) at least one copolymer containing vinylaromatic monomers,
D) at least one filler,
E) at least one low molecular weight halogen-free acid
and, if desired, additionally
F) at least one polyalkyl acrylate and
G) at least one flame retardant and
H) at least one additive,
and which are chracterized by the fact that they contain, as further components,
I) at least one aromatic or partially aromatic polyester or a mixture thereof.
In addition, the present invention relates to the use of the molding compositions for the preparation of shaped articles, films or fibers and to the shaped articles that are prepared therefrom.
Filled polycarbonate molding compositions containing graft polymers based on dienes (ABS) or acrylates (ASA) and styrene copolymers are known. It is also known that they can be equipped with diverse flame retardants. Such molding compositions are mainly used for the-manufacture of shaped articles for, say, the motorcar industry.
DE-A1 4,034,336 discloses polycarbonate molding compositions in which the antidrip agents used are polyfluorinated alkanesulfonic acid derivatives or polyfluorinated carboxylic acid derivatives instead of polytetrafluoroethylene. The molding compositions described therein show improved penetration impact resistance at low temperatures and short overall burning times, but do not satisfy the present-day requirements regarding freedom from halogens, on the one hand, and show relatively low heat deformation resistance, on the other hand.
Filled molding compositions based on polycarbonate and comprising styrene copolymers containing oxazoline groups and, as supplementary components, polyesters, particularly partially aromatic polyesters, are disclosed by DE-A1 1,960,198. They are distinguished by good strength properties, and good elongation at break and impact resistance. However, the low-temperature damage factor of such molding compositions is unsatisfactory.
WO 96/06136 and EP-B 1,391,413 describe polycarbonate molding compositions which are filled with talcum having an aspect ratio of from 4 to 40 and from 4 to 24 respectively and a particle size of less than 44 and less than 10 &mgr;m respectively, for which reason the parts that are prepared therefrom show a low tendency to distortion and have good impact resistances. According to the first-named specification the copolymer that is present in the molding compositions should have as high a molecular weight as possible. According to the last-named specification, the polycarbonate molding compositions can contain added amorphous polymers, including amorphous polyesters. Drawbacks of the said molding compositions are that they do not flow well and are difficult to process. Furthermore, they suffer from the drawback that the notched impact strength is insufficient for many purposes.
EP-A 1,522,397 discloses polycarbonate molding compositions which may contain polyalkylene terephthalates and which, when flame-treated, do not become deformed or form drops of flaming substance. They can be obtained by mixing their components with aramides and sulfonates. This has the disadvantage that the tenacity of corresponding molding compositions is considerably reduced.
EP-A 1,576,948 proposes that basic impurities which can cause degradation of the polycarbonate and which can be entrained into the molding compositions via recycled ABS, be neutralized by adding polymer resins containing acid groups. As examples thereof poly(meth)acrylic acid or partially saponified poly(meth)acrylates are mentioned. Their molecular weights (weight average M
w
) are preferably up to 500,000 g/mol. The molding compositions described in EP-A 1,576,948 may contain aromatic polyesters as one of their supplementary components. These molding compositions are not impact-resistant or tenacious enough for many applications.
Molding compositions revealed in JP-A 9/137054 can contain saturated polyesters. In order to keep down the decomposition of the polycarbonate, these molding compositions are filled with neutral talcum, which, however, requires an additional technical process step and is therefore elaborate and cost-intensive.
It is an object of the present invention to provide polycarbonate molding compositions which do not suffer from the above drawbacks. In particular, the polycarbonate molding compositions should be easy to process to large shaped articles suitable for use as external autobody parts. Since they are thus required to replace metal, polycarbonate molding compositions must be found which satisfy a wide range of stringent demands.
This object is achieved by the molding compositions defined above. Special embodiments are given in the sub-claims and description.
Component A
The component A present in the molding compositions of the invention comprises a polycarbonate or a mixture of two or more different polycarbonates. Preferred molding compositions of the invention contain from 1 to 97.35 wt %, based on the total weight of the molding compositions, of component A. We particularly prefer molding compositions of the invention which contain from 10 to 91.9 wt %, based on the total weight of the molding compositions, of component A.
We prefer to use halogen-free polycarbonates as component A. Suitable halogen-free polycarbonates are for example those based on diphenols of the general formula I
in which Q is a single bond or denotes a C
1
-C
3
alkylene group, a C
2
-C
3
alkylidene group, a C
3
-C
6
cycloalkylidene group, a C
6
-C
12
arylene group, or —O—, —S— or —SO
2
— and m is an integer from 0 to 2.
The diphenols I may optionally carry substituents on the phenylene radicals, for example C
1
-C
6
alkyl or C
1
-C
6
alkoxy.
Preferred diphenols of formula I are for example hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane and 1,1-bis(4hydroxyphenyl)cyclohexane. Particularly preferred are 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)cyclohexane, and also 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
Both homopolycarbonates and copolycarbonates are suitable for use as component A. In addition to bisphenol A homopolymer, the copolycarbonates of bisphenol A are preferred.
The suitable polycarbonates may be branched in known manner, preferably by the incorporation of from 0.05 to 2.0 mol %, based on the sum of diphenols used, of at least trifunctional compounds, such as those containing three or more phenolic OH groups.
Particularly suitable polycarbonates have been found to be those having relative viscosities &eegr;
rel
of from 1.10 to 1.50, particularly from 1.25 to 1.40. This corresponds to average molecular weight M
w
(weight average) of from 10,000 to 200,000, preferably from 20,000 to 80,000.
The diphenols of the general formula I are known per se or can be manufactured by known processes.
The preparation of the polycarbonates can take place, for example, by effecting reaction of diphenols with phosgene in the interface process or with phosgene in the homogeneous phase process (so-called pyridine process), the molecular weight required in each case being attained in known manner by adding an appropriate amount of known chain stopper. (For information on polydiorganosiloxane-containing polycarbonates see for example DE-OS 3,334,782).
Suitable chain stoppers are for example phenol, p-tert-butylphenol and also long-chain alkylphenols such as 4-(1,3-tetramethylbutyl)phenol, according to DE-OS 2,842,005, or monoalkylphenols or dialkylphenols having a total of from 8 to 20 carbon atoms in the alkyl substituents according to DE-A 3,506,472, such as p-nonylphenyl, 3,5-di-tert-butylphenol, p-tert-octylphenol, p-dodecylphenol, 2-(3,5-dimethylheptyl)phenol and 4-(3,5-dimethylheptyl)phenol.
‘Halogen-free polycarbonates’ means, for the purposes of the present invention, that the polycarbonates are composed of halogen-free dipheno

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