Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-10-03
2004-07-13
Thexton, Matthew A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S494000, C524S505000, C525S09200D, C525S089000, C525S098000, C525S099000
Reexamination Certificate
active
06762218
ABSTRACT:
The invention relates to thermoplastic molding compositions comprising, as substantive constituents,
A) from 5 to 96% by weight of a vinylaromatic polymer with a syndiotactic structure,
B) from 2 to 50% by weight of an inorganic filler,
C) from 1 to 15% by weight of a thermoplastic elastomer based on copolymers made from vinylaromatic monomers, dienes and, where appropriate, 1,1-diphenylethylene,
D) from 1 to 10% by weight of a compatibilizer, and, where appropriate,
E) from 1 to 15% by weight of an elastomeric particulate styrene-diene block copolymer whose diene content may have been completely or to some extent hydrogenated, and, where appropriate,
F) additives,
where the total of the percentages by weight of A) to F) is 100.
The invention further relates to the use of the thermoplastic molding compositions for producing fibers, films or moldings, and also to the resultant fibers, films or moldings.
Due to its crystallinity, syndiotactic polystyrene has a very high melting point of about 270° C., high stiffness and tensile strength, dimensional stability, a low dielectric constant and high chemicals resistance. Its mechanical property profile is even retained at temperatures above its glass transition temperature. The preparation of syndiotactic polystyrene in the presence of metallocene catalyst systems is known and described in detail in EP-A 0 535 582, for example.
The field of application of syndiotactic polystyrene is severely restricted by its brittleness.
There has therefore been a desire to reduce the brittleness of syndiotactic polystyrene, also termed SPS below, while at the same time improving its impact strength, breaking stress and stiffness.
EP-A 0 779 329 (Idemitzu Kosan) and WO-A 94/24 206 (Dow) have disclosed polymer blends made from syndiotactic polystyrene, from inorganic fillers, from polyphenylene ether and from a rubber component. However, the properties of the blends are still unsatisfactory, for example low flowability and complicated preparation.
EP-A 755 972 describes SPS which has been impact-modified using a mixture of, on the one hand, a block copolymer made from styrene and from hydrogenated butadiene and, on the other hand, a core-shell polymer with a butadiene polymer core. Molding compositions with inorganic fillers are not disclosed.
It is an object of the present invention, therefore, to prepare a thermoplastic molding composition which is based on vinylaromatic polymers with a syndiotactic structure and which combines high impact strength, high stiffness (modulus of elasticity), and good flowability (MVR, processability) and breaking stress.
We have found that this object is achieved by means of the thermoplastic molding compositions defined at the outset.
The use of the thermoplastic molding compositions for producing fibers, films or moldings has also been found, as have the resultant fibers, films and moldings.
As component A), the thermoplastic molding compositions of the invention comprise from 5 to 96% by weight, preferably from 20 to 80% by weight, in particular from 40 to 70% by weight, of a vinylaromatic polymer with a syndiotactic structure. The expression “with a syndiotactic structure” means for the purposes of the present invention that the polymers are substantively syndiotactic, i.e. the syndiotactic content determined by
13
C NMR is above 50%, preferably above 60%, of mmmm pentads.
Component A) has preferably been built up from compounds of the formula I
where:
R
1
is hydrogen or C
1
- to C
4
-alkyl, and
R
2
to R
6
independently of one another, are hydrogen, C
1
- to C
12
-alkyl, C
6
- to C
18
-aryl, or halogen, or where two adjacent radicals together are a cyclic group having from 4 to 15 carbon atoms, such as C
4
-C
8
-cycloalkyl, or anellated ring systems.
It is preferable to use vinylaromatic compounds of the formula I where
R
1
is hydrogen.
Particular substituents R
2
to R
6
which may be used are hydrogen, C
1
- to C
4
-alkyl, chlorine, phenyl, biphenyl, naphthalene or anthracene. Two adjacent radicals together may also be a cyclic group having from 4 to 12 carbon atoms, examples of resultant compounds of the formula I being naphthalene derivatives or anthracene derivatives.
Examples of these preferred compounds are:
Styrene, p-methylstyrene, p-chlorostyrene, 2,4-dimethylstyrene, 4-vinylbiphenyl, vinylnaphthalene and vinylanthracene.
It is also possible to use mixtures of various vinylaromatic compounds, but it is preferable to use just one vinylaromatic compound.
Particularly preferred vinylaromatic compounds are styrene and p-methylstyrene.
Mixtures of various vinylaromatic polymers with a syndiotactic structure may also be used as component A), but it is preferable to use just one vinylaromatic polymer, in particular syndiotactic polystyrene (SPS).
Vinylaromatic polymers (A) with a syndiotactic structure and processes for their preparation are known per se and are described in EP-A 535 582, for example. The preferred method of preparation is to react compounds of the general formula I in the presence of a metallocene complex and of a cocatalyst. Particular metallocene complexes used are pentamethylcyclopentadienyltitanium trichloride, pentamethylcyclopentadienyltrimethyltitanium, and pentamethylcyclopentadienyltitanium trimethylate.
The vinylaromatic polymers with a syndiotactic structure generally have a molar mass M
w
(weight-average) of from 5000 to 10,000,000 g/mol, in particular from 10,000 to 2,000,000 g/mol. The polydispersities M
w
/M
n
are generally from 1.1 to 30, preferably from 1.4 to 10.
Other vinylaromatic polymers which may be used as component A) and have a syndiotactic structure are syndiotactic star polymers based on vinylaromatic monomers. Examples of these star polymers are described in the earlier German patent application 196 34 375.5-44, in particular on page 2, line 21 to page 6, line 25, and in the examples.
As component B), the molding compositions of the invention comprise from 2 to 50% by weight, preferably from 5 to 45% by weight, in particular from 15 to 42% by weight, of fibrous or particulate inorganic fillers, or mixtures of these.
Examples of these are carbon fibers, glass fibers, glass mats, glass silk rovings or glass beads, or else potassium titanate whiskers, preferably glass fibers. Glass fibers may have been provided with a size or with a coupling agent. These glass fibers may be incorporated either as short glass fibers or else as continuous-filament strands (rovings). Preferred glass fibers comprise an aminosilane size and typically have a diameter D of from 1 to 30 &mgr;m, preferably from 3 to 20 &mgr;m, in particular from 5 to 15 &mgr;m. In the extruded molding compositions of the invention these glass fibers then have a length-to-diameter ratio of from 5 to 100, preferably from 10 to 80, in particular from 15 to 50.
Examples of materials which may be used as component B) are amorphous silica, magnesium carbonate, powdered quartz, mica, talc, feldspat or calcium silicates.
As component C), the thermoplastic molding compositions of the invention comprise from 1 to 15% by weight, preferably from 1 to 10% by weight, of copolymers made from vinylaromatic monomers and from dienes and, where appropriate, 1,1-diphenylethylene. This component C) may also be termed a thermoplastic elastomer (TPE).
Component C) is preferably prepared by anionic polymerization.
Particularly preferred components C) are three-block copolymers, particularly those which have been hydrogenated. The copolymers used as component C) are preferably those prepared from styrene, 1,1-diphenylethylene and butadiene, in particular styrene (S)/1,1-diphenylethylene (DPE)-butadiene-S/DPE three-block copolymers, the butadiene block having been hydrogenated (EB), i.e. (S/DPE)-EB-(S/DPE).
Other suitable copolymers or block copolymers have at least one block A made from vinylaromatic monomers a1) and 1,1-diphenylethylene or its derivatives a2) with substitution of the aromatic rings where appropriate by alkyl groups having up to 22 carbon atoms, obtainable by anionic polymerization, the copolymer or the block
Geprägs Michael
Knoll Konrad
BASF - Aktiengesellschaft
Keil & Weinkauf
Thexton Matthew A.
LandOfFree
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