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
1999-03-03
2001-05-22
Nutter, Nathan M. (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...
C525S393000, C524S264000, C523S212000, C526S279000
Reexamination Certificate
active
06235848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a crosslinkable molding material which contains a silane-grafted poly-&agr;-olefin.
2. Discussion of the Background
Polymers and polymer blends have for years become increasingly popular as materials which can be processed by a thermoplastic method. However, there is a substantial dependence of important performance characteristics, such as, for example, impact strength, tensile strength and tendency to creep, on the molecular weight. For this reason, the polymeric material should have as high a molecular weight as possible in order to possess a high impact strength, a high tensile strength and only a small tendency to creep in the finished article. However, when the molecular weight increases, the melt becomes so highly viscous that it can scarcely be processed. For this reason, if readily processible molding material is desired, it is necessary to make a compromise and accept a poorer impact strength and higher tendency to creep. This applies in particular to injection molding materials, which must be particularly readily flowable.
A further problem is encountered in the case of polymer blends. Since most polymers are incompatible with one another, it is initially possible, with strong shearing, to distribute one blend component in dispersed form or as a network in the other blend component. However, if the melt then enters a zone of low shearing or no shearing, for example a mold, the initially finely divided phase coalesces to larger droplets. The article obtained is thus extremely brittle after solidification and hence unusable.
In special cases, it is possible to achieve good dispersibility without subsequent coalescence by chemically linking the two blend components. In such cases, the two phases adhere to one another. The extent of the adhesion is frequently not sufficient, however, to achieve the desired high impact strength. This problem occurs if one attempts to impart impact strength to thermoplastic polyesters, such as polyethylene terephthalate or polybutylene terephthalate, by incorporating, or compounding rubbers which are functionalized, for example maleic anhydride-functionalized ethylene/propylene rubber (EPM) or ethylene/propylene/diene rubber (EPDM). For a sufficient reaction of the terminal OH groups of the polyester with the anhydride groups of the rubber, a subsequent solid-phase postcondensation is required, which gives rise to high process costs.
Therefore, there is a continuing need to provide molding materials which are readily processible and nevertheless give shaped articles having very high impact strength, high tensile strength and very small tendency to creep.
There is also a need for molding materials into which blend components can be readily mixed to form blends having stable phases.
There is also a need for polymer blends that have stabilized morphology and in which there is strong phase adhesion at the boundary.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide molding materials which are readily processible and nevertheless give shaped articles having very high impact strength, high tensile strength and very small tendency to creep.
A second object of the present invention is to provide molding materials into which blend components can be readily mixed to form blends having stable phases.
Another object of the present invention is to provide polymer blends that have stabilized morphology and in which there is strong phase adhesion at the boundary.
These and other objects are achieved according to the invention, by providing molding material, that includes:
(a) 3 to 98 parts by weight of one or more thermoplastic polymers,
(b) 2 to 97 parts by weight of a substantially amorphous, silane-grafted poly-&agr;-olefin, wherein the grafting silane includes at least one olefinic double bond and one to three alkoxy groups bonded directly to the silicon, and wherein the silane-grafted poly-&agr;-olefin has a melt viscosity at 190° C. in the range of 100 to 50,000 mPa.s; and
wherein the molding material contains 0 to less than 0.5 parts by weight of a reinforcing agent.
Another embodiment of the present invention provides a molded article, that includes the molding material of the invention.
Another embodiment of the present invention provides a method for preparing a molding material that includes:
(a) 3 to 98 parts by weight of one or more thermoplastics,
(b) 2 to 97 parts by weight of a substantially amorphous, silane-grafted poly-&agr;-olefin, wherein the grafting silane includes at least one olefinic double bond and one to three alkoxy groups bonded directly to the silicon, and wherein the silane-grafted poly-&agr;-olefin has a melt viscosity at 190° C. in the range of 100 to 50,000 mPa.s; and
wherein the molding material contains 0 to less than 0.5 parts by weight of a reinforcing agent;
wherein the process includes grafting a substantially amorphous poly-&agr;-olefin with the grafting silane, and mixing with one or more thermoplastic polymers.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
Preferably, the molding material of the present invention contains the following components:
(a) 3 to 98 parts by weight of one or more thermoplastics,
(b) 2 to 97 parts by weight of a substantially amorphous poly-&agr;-olefin which is grafted by free radical method with a silane which has at least one olefinic double bond and one to three alkoxy groups bonded directly to the silicon, this grafted poly-&agr;-olefin having a melt viscosity at 190° C. in the range of from 100 to 50,000 mPa.s, measured according to DIN 53019 in a rotational viscometer at a shear rate of 30.5 s
−1
, and the parts by weight of (a) and (b) summing to 100, and furthermore the molding material containing 0 to less than 0.5 part by weight of a reinforcing agent.
Molding materials having a higher content of reinforcing agents are the subject of German Patent Application No. 198 08 888.4 filed Mar. 3, 1998, the entire contents of which are hereby incorporated by reference.
In a more preferred embodiment, the molding material contains the following components:
(a) 44.5 to 98 parts by weight of one or more thermoplastics and
(b) 2 to 55.5 parts by weight of a substantially amorphous, silane grafted poly-&agr;-olefin.
In a particularly preferred embodiment, the molding material contains the following components:
(a) More than 80 to 97 parts by weight of one or more thermoplastics and
(b) 3 to less than 20 parts by weight of a substantially amorphous, silane-grafted poly-&agr;-olefin.
The thermoplastic of component (a) may be, for example, a polyolefin, a polystyrene, a polyphenylene ether, a polycondensate, such as polyester or polyamide, a polyurethane and/or a rubber.
The polyolefins are not particularly limiting, and any polyolefin known to those of ordinary skill may be used, for example polyethylene, polypropylene and poly-1-butene, but also copolymers of ethene, propene or 1-butene, either as random copolymers, such as, for example, LLDPE or propene/ethene random copolymers containing about 1-15% by weight of ethene, or as block copolymers, such as, for example, propene/ethene block copolymers. Likewise, the polyolefin may be a substantially amorphous polyolefin, as can be used as a grafting base for the component (b). The polyolefin may also contain a rubber as an impact modifier, for example ethene/propene rubber (EPM) or ethene/propene/diene rubber (EPDM).
Preferably, the polystyrene may be used either as such or in rubber-modified form; the choice of the rubber, for example butadiene rubber (BR), EPDM, styrene/butadiene/styrene block polymers (SBS) or polyoctenamer (TOR), being uncritical. The polystyrene may be present as a homopolymer; however, it may also contain comonomers, such as &agr;-methylstyrene, acrylonitrile, methyl methacrylate or N-phenylmaleimide
Bickert Peter
Wey Hans Guenther
Asinovsky Olga
Huels Aktiengesellschaft
Nutter Nathan M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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