Thermoplastic moulding compounds

Details Thermoplastic moulding compounds Thermoplastic moulding compounds

1999-07-08

2001-05-01

Nutter, N. (Department: 1711)

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

Synthetic resins

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

Reexamination Certificate

active

06225413

ABSTRACT:

This application claims the benefit under 35 U.S.C. 371 prior PCT International Application No. PCT/EP 97/07167 which has an International filing date of Dec. 19, 1997.
The present invention relates to thermoplastic molding materials containing
A) from 5 to 95% by weight of a vinylaromatic polymer having a syndiotactic structure and
B) from 5 to 95% by weight of a copolymer of a vinylaromatic monomer and 1,1-diphenylethylene or its derivatives which may be substituted on the aromatic rings by alkyl of up to 22 carbon atoms.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention furthermore relates to the use of the thermoplastic molding materials for the production of fibers, films and moldings and to the fibers, films and moldings produced therefrom.
Owing to its crystallinity, syndiotactic polystyrene has a very high melting point of about 270° C., high rigidity and tensile strength, dimensional stability, a low dielectric constant and high resistance to chemicals. The mechanical property profile is retained even at temperatures above the glass transition temperature. The preparation of syndiotactic polystyrene in the presence of metallocene catalyst systems is known and is described in detail, for example, in EP-A 0 535 582.
Owing to the remaining amorphous fraction in the syndiotactic polystyrene, the glass transition temperature is only about 100° C.
2. Description of the Related Art
EP-A 0 732 359 and WO 95/34586 describe thermoplastic molding materials comprising copolymers of vinylaromatic monomers and 1,1-diphenylethylene and further polymers, such as polyphenylene ether or transparent high impact polystyrene having glass transition temperatures above 130° C. However, these molding materials do not reach the high heat distortion resistance of molding materials which contain syndiotactic polystyrene and, in the case of blends with polyphenylene ether, tend to yellow.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to remedy the stated disadvantages and to provide thermoplastic molding materials which have a high glass transition temperature and are stable to high temperatures, dimensionally stable, have high rigidity and low electrical conductivity and do not tend to yellow.
DETAILED DESCRIPTION OF THE INVENTION
We have found that this object is achieved by the thermoplastic molding materials defined at the outset.
We have also found the use of the thermoplastic molding materials for the production of fibers, films and moldings as well as the fibers, films and moldings obtainable therefrom.
The novel thermoplastic molding materials contain, as component A), from 5 to 95, preferably from 10 to 75, in particular from 25 to 75, % by weight of a vinylaromatic polymer having a syndiotactic structure. Here, the expression “having a syndiotactic structure” means that the polymers are essentially syndiotactic, ie. the syndiotactic fraction as determined according to
13
C-NMR, is greater than 50%, preferably greater than 60%.
The component A) is preferably composed of compounds of the general formula I
where:
R
1
is hydrogen or C
1
-C
4
-alkyl,
R
2
to R
6
independently of one another, are each hydrogen, C
1
-C
12
-alkyl, C
6
-C
18
-aryl, or halogen, or two neighboring radicals together are a cyclic group of 4 to 15 carbon atoms, for example C
4
-C
8
-cycloalkyl or a fused ring system.
Vinylaromatic compounds of the formula I where R
1
is hydrogen are preferably used.
Particularly suitable substituents R
2
to R
6
are hydrogen, C
1
-C
4
-alkyl, chlorine, phenyl, biphenyl, naphthalene and anthracene. Two neighboring radicals together may furthermore be a cyclic group of 4 to 12 carbon atoms, resulting, for example, in naphthalene derivatives or anthracene derivatives as compounds of the general formula I.
Examples of such preferred compounds are:
styrene, p-methylstyrene, p-chlorostyrene, 2,4-dimethylstyrene, 4-vinylbiphenyl, vinylnaphthalene and vinylanthracene.
Mixtures of different vinylaromatic compounds may also be used, but only one vinylaromatic compound is preferably used.
Particularly preferred vinylaromatic compounds are styrene and p-methylstyrene.
Mixtures of different vinylaromatic polymers having a syndiotactic structure may also be used as component A), but preferably only one vinylaromatic polymer is used, in particular syndiotactic polystyrene (s-PS).
Vinylaromatic polymers having a syndiotactic structure-and processes for their preparation are known per se and are described, for example, in EP-A 535 582. In the preparation, a preferred procedure comprises reacting compounds of the general formula I in the presence of a metallocene complex and of a cocatalyst. In particular, pentamethylcyclopentadienyltitanium trichloride, pentamethylcyclopentadienyltitanium trimethyl and pentamethylcyclopentadienyltitanium trimethylate are used as metallocene complexes.
The vinylaromatic polymers having a syndiotactic structure generally have a weight average molecular weight M
w
of from 5000 to 10,000,000, in particular from 10,000 to 2,000,000 g/mol. The molecular weight distributions M
w
/M
n
are in general from 1.1 to 30, preferably from 1.4 to 10.
The thermoplastic molding materials contain, as component B), from 5 to 95, preferably from 25 to 90, in particular from 25 to 75, % by weight of a copolymer of a vinylaromatic monomer and 1,1-diphenylethylene or its derivatives which may be substituted on the aromatic rings by alkyl of up to 22 carbon atoms. Particularly suitable copolymers are those having a content of 1,1-diphenylethylene or its derivatives which is chosen so that the copolymer is readily compatible with the component A). This is evident, for example, from the fact that the blend with the component A) has a single glass transition temperature and can be readily determined by thermal analysis methods, for example DSC (differential scanning calorimetry). Advantageously, the copolymer contains from 5 to 65, preferably from 10 to 45, and very particularly preferably from 15 to 25, % by weight of 1,1-diphenylethylene or the corresponding molar amount of a derivative derived from 1,1-diphenylethylene. The weight average molecular weight M
w
of the component A is from 10,000 to 2,000,000 g/mol, preferably from 20,000 to 1,000,000 and very particularly preferably from 50,000 to 500,000, g/mol.
The copolymers which may be used as component B) are known per se. Their preparation is described in detail in DE-A 44 36 499 ({circumflex over (=)} WO 95/34586).
The sum of the components A) and B) is 100% by weight.
If required, additives or processing assistants or mixtures thereof may be added in conventional amounts to the novel thermoplastic molding materials.
These are, for example, nucleating agents such as salts of carboxylic, organic sulfonic or phosphoric acids, preferably sodium benzoate, aluminum tris(p-tert-butylbenzoate), aluminum trisbenzoate, aluminum tris(p-carboxymethylbenzoate) and aluminum triscaproate; antioxidants such as phenolic antioxidants, phosphites or phosphonites, in particular trisnonylphenyl phosphite; stabilizers such as sterically hindered phenols and hydroquinones. Lubricants and mold release agents, dyes, pigments and plasticizers may also be used.
Organophosphorus compounds, such as phosphates or phosphine oxides may be used as flameproofing agents.
Examples of phosphine oxides are triphenylphosphine oxide, tritolylphosphine oxide, trisnonylphenylphosphine oxide, tricyclohexylphosphine oxide, tris-(n-butyl)phosphine oxide, tris-(n-hexyl)phosphine oxide, tris-(n-octyl)phosphine oxide, tris(cyanoethyl)phosphine oxide, benzylbiscyclohexylphosphine oxide, benzylbisphenylphosphine oxide and phenylbis-(n-hexyl)phosphine oxide. Triphenylphosphine oxide, tricyclohexylphosphine oxide, tris-(n-octyl)phosphine oxide and tris(cyanoethyl)phosphine oxide are particularly preferably used.
Particularly suitable phosphates are alkyl- and aryl-substituted phosphates. Examples are phenyl bisdodecyl phosphate, phenyl bisneopentyl phosphate, phenyl ethyl hydrogen phosphate, phenyl bis(3,5,5-trimethylh

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