Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-11-07
1999-03-16
Warzel, Mark L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 80, 525 85, 525 86, C08L 5500
Patent
active
058831878
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a polymer composition comprising an acrylate rubber substrate which is grafted with a vinyl aromatic monomer and an unsaturated nitrile monomer and optionally one or more compatible comonomers. More specifically the invention relates to a grafted acrylate rubber substrate wherein the rubber is a copolymer of butyl acrylate (BA) and a nitrile monomer. The resulting polymer exhibits improved Izod impact strength over similar compositions wherein the butyl acrylate rubber substrate does not contain a nitrile comonomer. The claimed compositions are useful as molding and extrusion compounds.
2. Description of Related Art
Acrylate rubber polymers grafted with styrene and acrylonitrile (ASA polymers) are well known in the art.
U.S. Pat. No. 4,224,419 to Swoboda et al. teaches an ASA polymer which uses a bimodal butyl acrylate substrate. At column 5, lines 5-10 and column 6, lines 64-67 Swoboda teaches using "additional monomers" in the butyl acrylate rubber substrate.
U.S. Pat. No. 4,753,988 to Henton et al. is an improvement on the Swoboda ASA polymer. At column 2, line 35 to column 3, line 4 and claims 2, 3 and 4 Henton teaches using 0 to 20% by weight of a comonomer such as acrylonitrile (AN) or methyl methacrylate (MMA) in the butyl acrylate rubber substrate.
U.S. Pat. No. 4,880,875 to Wassmuth et al. is another improvement on the Swoboda ASA polymer. At column 3, lines 15-51 Wassmuth teaches using 0 to 30% by weight, preferably 20 to 30% by weight of a comonomer, e.g. S, AN or MMA in the BA rubber substrate.
U.S. Pat. No. 5,120,788 to Seitz et al. teaches up to 50% by weight of a comonomer in butyl acrylate rubber substrate in column 3, lines 17-22.
U.S. Pat. No. 5,252,666 to Seitz et al. teaches use of 0.1 to 20% by weight of a hydroxyl alkyl acrylate comonomer in butyl acrylate rubber substrate to obtain improved notched izod impact and lower molding temperature.
SUMMARY OF THE INVENTION
The present invention is directed to a polymer composition comprising (A) a first grafted acrylate rubber substrate having an average rubber phase particle size of from about 0.05 to about 0.2 micron; (B) a second grafted acrylate rubber substrate having an average rubber phase particle size of from about 0.2 to about 2 microns; and (C) a matrix polymer wherein each of the first and second rubber substrates are grafted with (i) a vinyl aromatic monomer; (ii) an unsaturated nitrile monomer; and (iii) optionally a compatible polymerizable comonomer based on the total weight of the grafted rubber substrate wherein at least one of the acrylate rubber substrates is a copolymer of from 83 to 98 percent by weight of an acrylate monomer and from 17 to 2 percent by weight of an unsaturated nitrile monomer based on the total weight of the acrylate nitrile monomer copolymer rubber; and wherein the composition has an Izod impact value of at least 80 joules/meter (J/M) when tested at 23.degree. C. according to ASTM D-256 using a test specimen of 6.35 cm.times.1.27 cm.times.0.32 cm. Preferably the Izod value is at least 100 J/M.
DESCRIPTION OF THE INVENTION
The preferred acrylate for use in the present invention is butyl acrylate and the preferred unsaturated nitrile monomer is acrylonitrile.
In a preferred embodiment of the invention, the compositions comprise an acrylate rubber substrate that is bimodal having a first acrylate rubber component that has a weight average rubber phase particle size (RPPS) of from about 0.05 to about 0.2 micron, preferably from about 0.07 to about 0.15 micron and a second acrylate rubber component that has a weight average rubber phase particle size of from about 0.2 to about 2 microns, preferably from about 0.3 to about 0.8 micron. These bimodal compositions are well known in the prior art, e.g. Aubrey et al. U.S. Pat. No. 3,509,237; Swoboda et al. U.S. Pat. No. 4,224,419; Henton et al. U.S. Pat. No. 4,753,988; and Seitz et al. U.S. Pat. No. 4,880,875 and the teaching of these patents are incorporated herein by referen
REFERENCES:
patent: 4581408 (1986-04-01), Trabert et al.
patent: 4753988 (1988-06-01), Henton et al.
patent: 4880875 (1989-11-01), Wassmuth et al.
Auclair Richard Maurice
Chang Moh-Ching Oliver
Bayer Antwerpen S.A./N.V.
Gil Joseph C.
Preis Aron
Warzel Mark L.
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