Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-10-09
2000-08-15
Wilson, Donald R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
526201, 5263285, C08F27902, C08F22014, C08F 200
Patent
active
06103830&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a methacrylic resin having excellent impact resistance. More particularly, the present invention relates to a methacrylic resin which has improved impact resistance, while it retains the excellent weatherability, surface gloss, rigidity, and brightness of color tone inherent in methacrylic resins and optionally further retains transparency and other properties.
BACKGROUND ART
Methacrylic resins are used in a wide range of indoor and outdoor applications because they are excellent in weatherability, rigidity, and molding appearance. However, since methacrylic resins are brittle polymers in themselves, there are cases where they arise troubles due to their insufficient impact resistance according to the ways in which they are used.
Investigations on improvements in the impact resistance of methacrylic resins have been made from long ago. Known techniques for the improvements include: a method in which an acrylic rubber having a multilayer structure is blended with a methacrylic resin (Examined Japanese Patent Publication No. 55-27576, Unexamined Published Japanese Patent Application No. 3-199213, and Examined Japanese Patent Publications Nos. 58-1694, 59-36645, 59-36646, 63-8983, and 62-41241); a method in which monomers containing methyl methacrylate as the main component are graft-polymerized with a conjugated diene polymer (Examined Japanese Patent Publication No. 46-18491 and Unexamined Published Japanese Patent Applications Nos. 55-147514 and 55-123612); and a method in which monomers containing methyl methacrylate as the main component are graft-polymerized with a rubber-like polymer obtained from either a copolymer of an aromatic vinyl compound and a conjugated diene or a conjugated diene polymer by hydrogenating at least 70%, substantially at least 90%, of the olefinically unsaturated bonds, i.e., double bonds, thereof (Unexamined Published Japanese Patent Applications Nos. 1-297413, 2-302459, and 3-295643).
The first method, in which an acrylic rubber having a multilayer structure is blended with a methacrylic resin, is the technique currently most extensively used industrially. The multilayered acrylic rubber has a spherical structure made up of three or more layers comprising, stacked substantially alternately, rigid layers made mainly from methyl methacrylate and flexible layers made mainly from an acrylic ester such as butyl acrylate. The degree of crosslinking of the flexible layers, in particular, is controlled by changing polyfunctional monomers. A feature of this blending technique resides in that since the flexible layers have been sufficiently crosslinked, the rubber particles are neither deformed nor broken by the mechanical shearing force which the particles receive during extrusion or injection molding. Although this method is an excellent technique for improving a performance, i.e., impact resistance, of methacrylic resins, it has problems including the following. Since the rubber ingredient has a multilayer structure containing rigid layers, it is necessary to add the rubber ingredient in a large amount for obtaining the desired impact resistance. Moreover, since multistage polymerization should be conducted repeatedly in forming the multilayer structure, the production efficiency is low, resulting in an increased cost.
The second method, in which monomers containing methyl methacrylate as the main component are graft-polymerized with a conjugated diene polymer, is characterized in that since the rubber ingredient contains a large amount of double bonds, it undergoes crosslinking reactions like the rubber ingredients in ABS resins and high-impact polystyrenes and, hence, the rubber particles are neither deformed nor broken by the mechanical shearing force which the particles receive during extrusion or injection molding. In addition, the second method is excellent also in cost because the production efficiency is high. However, this technique has problems, for example, in that the rubber ingredient contains a large amount of double
REFERENCES:
patent: 5998554 (1999-12-01), Yokoo
Derwent Abstract for EP 60042 A which corresponds to JP 63-8983.
Derwent Abstract for EP 19372 A which corresponds to JP 55-147514.
Derwent Abstract for EP 14574 A which corresponds to JP 55-123612.
Derwent Abstract for USP 4,180,529 A which corresponds to JP 62-41241.
Derwent Abstract for JP 53058554 A which corresponds to JP 58-1694.
Derwent Abstract for JP 52056150 A which corresponds to JP 59-36646.
Derwent Abstract for DE 2619922 which corresponds to JP 59-36645.
Hirota Satoru
Kinoshita Hideo
Sasagawa Masahiro
Asahi Kasei Kogyo Kabushiki Kaisha
Wilson Donald R.
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