Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-11-04
1995-02-21
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
525 68, 525 70, 525 88, 525 92, 524127, C08L 2504, C08L 2510, C08L 7112
Patent
active
053916115
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a styrenic resin composition. More particularly, it pertains to a styrenic resin composition which has favorable release properties from a hot mold, is markedly improved in impact resistance without losing the excellent heat resistance and high mechanical strength that are inherent in a styrenic resin having syndiotactic configuration and, as desired, is gifted with favorable flame retardance.
BACKGROUND ART
Though a styrenic resin has heretofore been widely used in a variety of fields as a general-purpose resin, it has suffered the serious disadvantage of its inferior impact resistance in general. In order to improve the impact resistance of a styrenic polymer, there is industrially produced a so-called rubbery modified styrenic polymer composition, that is, a substantial mixture of a rubbery polymer-styrene graft copolymer and polystyrene in which a part of styrene is graft-polymerized onto a rubbery polymer and the remainder thereof constitutes polystyrene by a method in which styrene is blended with a rubbery polymer or a method in which styrene is polymerized in the presence of a rubbery polymer.
In particular it is known that the impact strength of a styrenic resin composition is enhanced by the use of a perfectly block-type styrene/butadiene copolymer or a taper block-type styrene/butadiene copolymer. For example, there are disclosed an impact-resisting polystyrene in which a perfect block-type styrene/butadiene copolymer is used as the rubbery polymer (refer to Japanese Patent Application Laid-Open No. 165413/1988) and an impact-resisting polystyrene in which a taper block-type styrene/butadiene copolymer is used as the rubbery polymer (refer to Japanese Patent Application Laid-Open Nos. 71549/1977 and 48317/1988).
However, it can not be said that the above-disclosed impact-resisting styrenic resin is always sufficient in the balance among impact resistance, heat resistance, mechanical strength, etc., and thus a styrenic resin which is highly balanced in the aforesaid properties is desired according to the purpose of use thereof.
Being produced by radical polymerization, the generally used styrenic resin is of atactic configuration in its stereoregularity and noncrystalline. Accordingly it can not be said that such styrenic resin is sufficiently high in impact resistance and mechanical strength, thus limiting the improvement in these properties.
In order to develop a styrenic resin composition which has further excellent properties beyond the limit of the improvement in properties inherent in the conventional styrenic resin, the group of the present inventors continued research and proposed a highly impact-resistant styrenic resin composition which comprises a styrenic polymer having high degree of syndiotactic configuration compounded with a rubbery polymer having a styrenic unit as one component (Refer to Japanese Patent Application Laid-Open No. 146944/1989).
Nevertheless, since there has been used in the above-mentioned composition, a rubbery polymer having a product of weight-average molecular weight and styrenic monomer unit content of less than 30,000, the composition has suffered the disadvantages that it brings about a decrease in rigidity at the time of molding presumably attributable to poor dispersion of the rubber and insufficient release properties; and besides the molding produced therefrom is not sufficiently improved in Izod impact strength with low heat resistance (Vicat softening point).
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a styrenic resin composition which has favorable release properties from a hot mold which are the conditions of promoting crystallization and is greatly improved in impact resistance without losing the excellent heat resistance and high mechanical strength that are inherent in a styrenic resin having syndiotactic configuration.
It is another object of the present invention to provide a styrenic resin composition which is gifted with favorable flame retardance in
REFERENCES:
patent: 4946897 (1990-08-01), Albizzati et al.
patent: 5164479 (1992-11-01), Funaki et al.
patent: 5183871 (1993-02-01), Yamasaki et al.
patent: 5219940 (1993-06-01), Nakano
patent: 5292587 (1994-03-01), Furaki et al.
Funayama Michio
Mihara Masami
Miura Shin'ichi
Takamatsu Keiji
Hamilton, III Thomas
Idemitsu Kosan Co. Ltd.
Seidleck James J.
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