Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2001-01-31
2001-10-16
Pezzuto, Helen L. (Department: 1713)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S051000, C556S056000
Reexamination Certificate
active
06303806
ABSTRACT:
DESCRIPTION
The present invention relates to star polymers obtainable by polymerization of vinylaromatic monomers with a branching monomer unit containing at least two vinylaromatic functional radicals in the presence of a catalyst obtainable from A) a transition-metal complex from sub-group II to VIII, B) a cation-forming agent and C), if desired, an aluminum compound.
The present invention furthermore relates to a process for the preparation of these star polymers and to their use for the production of fibers, films and moldings, in particular injection molding materials [sic], and the resultant fibers, films and moldings.
Owing to its crystallinity, syndiotactic polystyrene has a very high melting point of about 270° C., high rigidity, tensile strength and dimensional stability, a low dielectric constant and high chemicals resistance. The mechanical property profile is retained even at above the glass transition temperature. The preparation of syndiotactic polystyrene in the presence of metallocene catalyst systems is disclosed, for example, in EP-A-210 615.
The low toughness and poor solubility, even in chlorinated solvents, and the low compatibility in blends with thermoplastics, for example PS, PB, PMMA, PE, PP, EP, PA6, PA66, PET, PBT, ABS, ASA etc., are disadvantageous. Furthermore, crystallization of the syndiotactic polystyrene frequently occurs from a conversion of as low as around 10%.
EP-A-572 990 describes metallocene-catalyzed copolymers of styrene and ethylene which have improved compatibility and high elasticity. However, these copolymers do not have the high stereotacticity and therefore do not achieve the high-temperature properties of syndiotactic polystyrene.
Copolymers of styrene and divinylbenzene are described in EP-A-311 099 and EP-A-490 269. Under the reaction conditions, only one vinyl group of the divinylbenzene reacts. The remaining vinyl groups are used for grafting reactions or crosslinked by means of free radicals on conditioning at about 230° C., molecular weights of from 1,000,000 to 6,000,000 only being obtained after this crosslinking reaction.
Star polymers belong to the class of the branched polymers (Falbe, Römpp Chemie Lexikon, Georg Thieme Verlag, 9th Edition, Stuttgart 1992, page 4304). They are usually prepared by polymerization of monomers with polyfunctional initiators, polyaddition of, for example, epoxides onto polyhydric alcohols or coupling of pre-prepared polymers, for example Li polystyrene, onto a center, for example silicon tetrachloride.
It is an object of the present invention to provide star polymers made from vinylaromatic monomers, which polymers simultaneously have high molecular weight and low melt viscosities, and a high end-group functionality for graft reactions, crosslinking reactions and other polymer-analogous reactions. Furthermore, the star polymers should have an essentially syndiotactic structure, ie. have a syndiotacticity of greater than 30%, in particular greater than 60%.
We have found that this object is achieved by the star polymers defined at the outset containing the branching monomer units containing at least two vinylaromatic functional radicals.
These polymers have high molecular weights of from 500,000 to 10,000,000 at the same time as low melt viscosities of less than 500 ml/10 min at 290° C. and a weight of 10 kg, and have significantly greater end-group functionalities compared with syndiotactic styrene of comparable molecular weight. In general, the endgroup functionality is greater than 0.5 mol %, particularly preferably greater than 0.8 mol %.
These properties can be modified within a broad range by means of the molar ratio between the vinylaromatic monomer and branching monomer units according to the invention. The molar ratio between vinylaromatic monomers and the branching monomer unit is generally from 10,000,000:1 to 10:1.
The novel star polymers have a syndiotacticity greater than 60%, in general greater than 90%.
The branching monomers can, according to the invention, be compounds of the formula I
where
R
a
is hydrogen, halogen or an inert organic radical having up to 20 carbon atoms, where, in a case where p≧2, the two radicals R
a
may be identical or different and can, together with the metal atom to which they are bonded, form a 3- to 8-membered ring, and R
a
may furthermore be a conventional complex ligand if M is a transition metal;
R
b
is hydrogen, C
1
-C
4
-alkyl or phenyl;
R
c
is hydrogen, C
1
-C
4
-alkyl, phenyl, chlorine or an unsaturated hydrocarbon radical having 2 to 6 carbon atoms;
M is C, Si, Ge, Sn, B, Al, Ga, N, P, Sb, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Zn or Cd; p
1
n is 2-6;
m is 0-20; and
p is 0-4;
with the proviso that the sum n+p corresponds to the valence of M.
These monomers can be obtained, for example, via the Grignard compounds of chloro(alkyl)styrenes with the corresponding carbon, metal or transition-metal compounds, for example the halogen compounds. Such reactions have been described, for example, for the case where M is silicon, germanium or tin in K. Nakanishi, J. Chem. Soc. Perkin Trans. I, 1990, page 3362.
Particular preference is given to branching monomer units of the formula I in which M is carbon, silicon, germanium, tin or titanium, since they are readily accessible. The index m is preferably from 0 to 8, particularly preferably from 0 to 4.
The present invention also relates to the novel titanium-containing monomers of the formula Ia
and in particular the titanium compound of the formula Ib
where R
a
, R
b
, R
c
, m, n and p are as defined above.
The inert organic radicals R
a
are of no great significance for the process. Rather, they serve merely to saturate the free valences on M and can be selected in accordance with ready availability. For example, aliphatic, cycloaliphatic, aryl, heteroaryl or aralkyl radicals are suitable. Examples of aliphatic radicals are alkyl, alkoxy, alkenyl and alkynyl radicals having, for example, from 1 to 2 or 20 carbon atoms. Examples of cycloaliphatic radicals are cycloalkyl radicals having 3 to 8 carbon atoms. A methylene group in the alkyl or cycloalkyl radicals can also be replaced by an ether oxygen atom. Examples of aryl radicals are phenyl and naphthyl radicals, in which two phenyl groups can also be linked to one another via an oxygen atom. Examples of aralkyl radicals are those having 7 to 20 carbon atoms produced by combining a phenyl radical with an alkyl radical. Examples of heteroaryl radicals are pyridyl, pyrimidyl and furyl radicals. These radicals may also be further substituted, for example by alkyl, alkoxy, halogen, such as fluorine, chlorine or bromine, cyano, nitro, epoxy, carbonyl, ester groups, amides, etc. It is also possible for two of the radicals R
a
, together with the atom M, to form a 3- to 6-membered ring, for example by two radicals R
a
forming an alkylene chain, in which one or more CH
2
groups may also be replaced by ether oxygen atoms.
If M is a transition metal, R
a
can also be a conventional &sgr;- or &pgr;-bonded complex ligand, such as ethylene, allyl, butadiene, cyclopentadiene, mono- or polysubstituted cyclopentadienes, such as methylcyclopentadiene or pentamethylcyclopentadiene, benzene, cyclohexadiene, cycloheptatriene, cycloheptadiene, cyclooctatetraene, cyclooctatriene, cyclooctadiene, carbonyl, oxalato, cyano, isonitrile, fulminato-C, fulminato-O, cyanato, dinitrogen, ethyelenediamine, diethylenetriamine, triethylenetetramine, ethylenediamine tetraacetate, nitrosyl, nitro, isocyano, pyridine, &agr;,&agr;-dipyridyl, trifluorophosphine, phosphine, diphosphine, arsine or acetylacetonato.
R
b
is particularly preferably hydrogen or methyl. R
c
is hydrogen, C
1
-C
4
-alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl or butylisomers, phenyl, chlorine or an unsaturated hydrocarbon radical having 2 to 6 carbon atoms, such as vinyl, allyl, methallyl, butenyl or pentenyl.
Particularly suitable vinylaromatic compounds are those of the formula II
where
R
1
is hydrogen or C
1
- to C
4
-alkyl,
R
2
Geprags Michael
Wunsch Josef
BASF - Aktiengesellschaft
Keil & Weinkauf
Pezzuto Helen L.
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