Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-03-17
2000-04-18
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 71, 525 75, 525191, 525316, 525322, 525404, C08L 5104
Patent
active
06051650&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a rubber-reinforced thermoplastic resin composition excellent in impact resistance, fluidity during high-temperature processing, resistance to coloration during high-temperature retention, impact resistance during high-temperature retention, and resistance to gelation during high-temperature retention.
BACKGROUND ART
Heretofore, rubber-reinforced thermoplastic resin compositions such as an ABS resin have been widely used as general-purpose resins having well-balanced impact resistance, moldability, surface gloss and other mechanical properties and materials usable as a substitute of engineering plastics.
For such a rubber-reinforced thermoplastic resin composition, impact resistance, moldability and other mechanical properties under ordinary conditions as well as these physical properties during high-temperature processing or high-temperature retention, i.e., thermal stability, are very important. When rubber-reinforced thermoplastic resin compositions are extrusion-granulated or molded, deterioration by heat generated by shear or heat retention can often occur, such as decrease in impact resistance of a molded product, yellowing of resin, and deterioration of surface gloss. Further, when heat retention proceeds, a gel-like material is produced in the extruder or molding machine and incorporated in the molded product as a contaminant in the resin, causing problems. Moreover, when a large-sized product is molded or a product having a complicated shape or small thickness is molded, the resin is often molded at a high temperature so that it can be easily extended all over the interior of the mold. In this case, problems often arise such as decrease in impact resistance, fluidity and surface gloss.
Further, the foregoing decrease in fluidity during high-temperature processing, decrease in impact resistance during high-temperature retention, coloration during high-temperature retention, and gelation during high-temperature retention remarkably appear when particles of a rubber polymer having a large particle diameter designed to have an excellent impact resistance under ordinary extrusion molding conditions are used or when particles of a rubber polymer having a low gel fraction content are used. Therefore, it has been difficult to obtain a rubber-reinforced thermoplastic resin composition excellent in impact resistance under ordinary extrusion molding conditions, fluidity during high-temperature processing, impact resistance during high-temperature retention, resistance to coloration during high-temperature retention, and resistance to gelation during high-temperature retention, when the particles of a rubber polymer have a large particle diameter or a low gel fraction content.
In order to solve these problems, there has been proposed to reduce the added amount of the rubber polymer or to increase the gel fraction content of the rubber polymer. However, these approaches are undesirable in the design attaining high impact resistance.
Alternatively, there has been proposed to increase the percent graft amount of a vinyl compound graft-polymerized to the particles of a rubber polymer shown by the following equation: ##EQU1## This approach can maintain surface gloss at high temperatures but disadvantageously causes decrease in impact resistance or fluidity at ordinary molding temperature.
Further, there has been proposed to employ an approach which comprises adding various oxidation inhibitors during extrusion or molding to inhibit the coloration or decrease in impact resistance due to heat deterioration. However, this approach cannot always inhibit the decrease in impact resistance or fluidity at high temperatures or the decrease in impact resistance during high-temperature retention. For the design attaining good impact resistance and surface gloss, U.S. Pat. No. 4,009,227 employs a combination of particles of rubber having a middle to large particle diameter with particles of a rubber polymer having a small particle diameter. However, this approach requires a
REFERENCES:
patent: 5283286 (1994-02-01), Takahashi et al.
patent: 5332854 (1994-07-01), Yokota et al.
Endo Shigeru
Nagao Makiko
Yamanaka Toshinori
Asahi Kasei Kogyo Kabushiki Kaisha
Asinovsky Olga
Seidleck James J.
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