Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-12-16
1998-12-29
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
526346, 526347, C08F29300
Patent
active
058543538
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to thermoplastic molding compounds comprising as essential components formulae I and II ##STR2## where R.sub.1 is H or alkyl of 1-22 carbon atoms, the general formula I, the general formula II, compound, of polymers other than A), and compound, of additives and processing aids.
Molded thermoplastics are hard and rigid at room temperature. At higher temperatures, however, the usefulness of thermoplastics is limited by the glass transition temperature or by the melting point in the case of partly crystalline thermoplastics. This also applies to atactic polystyrene, whose glass transition temperature is 101.degree. C. and which does not crystallize because of the irregular orientation of the phenyl rings. Lately it has been possible, by means of metallocene catalysis, to produce a syndiotactic polystyrene whose crystalline regions have a melting point of 275.degree. C. (e.g. EP-A-210 615, EP-A-535 582, EP-A-312 976 and EP-A-318 833).
Syndiotactic polystyrene, however, has various disadvantages. For instance, the processing range for the production of moldings is relatively small, since the product has to be heated to above the melting point on the one hand, but it will decompose at above 310.degree. C. on the other. The consequence is that the product readily depolymerizes back to styrene monomer during processing.
Furthermore, the product crystallizes in various forms which have a significant effect on the performance characteristics of the molded part. Finally, only the crystalline regions have the high melting point; the amorphous regions still have a glass transition temperature of 101.degree. C. as before.
The polymerization of 1,1-diphenylethylene with styrene is known and described in Bulletin Chem. Soc. Jap. 40 (1967), 2569, and in J. Polymer Sci., Part B, 8 (1970), 499. However, the method described in these publications has the disadvantage that the polymerization proceeds extremely slowly and the conversion is incomplete if higher softening points are to be obtained.
The diphenylethylene monomer remaining in the copolymer lowers its glass transition temperature and so makes it worthless for commercial purposes.
It is an object of the present invention to provide thermoplastic molding compounds which are free of the above-described disadvantages, which have a glass transition temperature of at least 130.degree. C. and which have a residual monomer content of <4000 ppm.
We have found that this object is achieved by thermoplastic molding compounds as claimed in claim 1.
Preferred molding compounds of this invention are disclosed in the subclaims.
Component A of the thermoplastic molding compounds of this invention comprises from 10 to 100, preferably from 40 to 100, especially from 60 to 100, % by weight, based on the proportion of polymeric components, of a copolymer having units derived from monomers I and II.
The monomers of the general formula I are 1,1-diphenylethylene and its derivatives where the aromatic rings are substituted by alkyl having up to 22 carbon atoms. Preferred alkyl substituents are alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl and tert-butyl, to name but a few. However, the unsubstituted 1,1-diphenylethylene itself is particularly preferred.
The monomers of the general formula II are styrene and its derivatives where there is substitution by alkyl having 1 to 4 carbon atoms in the .alpha.-position or on the aromatic ring. Preferred alkyl groups are those mentioned above as preferred for monomers of the formula I; unsubstituted styrene itself is particularly preferred.
The molar ratio of units derived from monomer I to units derived from monomer II is generally within the range from 1:1 to 1:25, preferably within the range from 1:1.05 to 1:15, particularly preferably within the range from 1:1.1 to 1:10. Since the monomers of the formula I generally do not homopolymerize, products having molar ratios of more than 1:1 are not readily obtainable.
The novel process for producing com
REFERENCES:
patent: 3280084 (1966-10-01), Zelinski et al.
patent: 3637554 (1972-01-01), Childers
patent: 3985830 (1976-10-01), Fetters et al.
patent: 4091053 (1978-05-01), Kitchen
1989.
Bull. Chem. Soc. Japan, vol. 40, 1967, pp. 2569-2572.
Polymer Letters, vol. 8, pp. 499-503, 1970. Aug. 22, 1989).
Gausepohl Hermann
Knoll Konrad
BASF - Aktiengesellschaft
Cain Edward J.
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