Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1997-11-10
2001-04-10
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S117000, C524S120000, C524S291000, C524S353000
Reexamination Certificate
active
06214909
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polystyrenic resin composition which comprises a styrenic polymer having the syndiotactic configuration as the main component, and a molded article thereof. More particularly, the present invention relates to a polystyrenic resin composition which has excellent heat resistance, chemical resistance, and mechanical strength, and shows excellent heat stability, such as small decrease in mechanical strength and little discoloration, in heat molding at a relatively high temperature, and a molded article prepared by using this polystyrenic resin composition which shows excellent resistance to heat aging, such as small decrease in physical properties and little discoloration, after use at a high temperature for a long time.
BACKGROUND ART
Styrenic polymers having the syndiotactic configuration (hereinafter, referred to as SPS, occasionally) show excellent heat resistance, chemical resistance, and water resistance. Particularly, SPS has been widely used as the material for various types of molded article to which heat resistance is required because of the excellent heat resistance.
On the other hand, the temperature of heat molding of SPS is higher than conventional thermoplastic resins because of the proper characteristic of SPS. The temperature of the resin during the molding reaches about 300° C. A still higher temperature or a longer residence time in a heated apparatus is sometimes required depending on the condition of molding. When SPS is used singly, a problem arises under such a severe condition in that the resin is degraded by the action of heat and oxygen although SPS has the excellent heat resistance as described above, and a molded article showing decrease in physical properties, such as mechanical strength, and inferior appearance, such as discoloration, tends to be obtained.
Similarly, when a molded article prepared by the single use of SPS is exposed to the air for a long time at a high temperature, a problem arises in that the resin is degraded by the action of heat and oxygen, and the molded article tends to show decrease in physical properties, such as mechanical strength, and inferior appearance, such as discoloration.
For solving the above problems, the present inventors have proposed a resin composition comprising SPS which additionally contains a phenolic antioxidant (Japanese Patent Application No. Heisei 5(1993)-289,290) and a resin composition comprising SPS which additionally contains a phenolic antioxidant and an antioxidant containing sulfur (Japanese Patent Application No. Heisei 6(1994)-384). However, the above problems have not been solved sufficiently.
DISCLOSURE OF THE INVENTION
In the above circumstances, the present inventors studied intensively to develop a resin composition comprising SPS which shows improved heat stability with respect to mechanical properties, appearance, and color in heat molding at a high temperature while the excellent characteristics of SPS are maintained, and a molded article of SPS which shows improved resistance to heat aging with respect to mechanical properties, appearance, and color after use in the air at a high temperature for a long time.
As the result of the above studies, it was found that the above object can be achieved by adding a combination of a phenolic antioxidant and an antioxidant containing phosphorus or a combination of a phenolic antioxidant, an antioxidant containing phosphorus, and an antioxidant containing sulfur to SPS or to a resin comprising SPS and other resins where desired. The present invention was completed based on this knowledge.
Accordingly, the present invention provides a resin composition which is represented by following Polystyrenic resin compositions 1 to 6, and a molded articles prepared by using any of these resin compositions.
[Polystyrenic Resin Composition 1]
A polystyrenic resin composition which comprises 100 parts by weight of (A) (a-1) a styrenic polymer having the syndiotactic configuration, 0.005 to 5.0 parts by weight of (B) a phenolic antioxidant, and 0.005 to 5.0 parts by weight of an antioxidant containing phosphorus.
[Polystyrenic Resin Composition 2]
A polystyrenic resin composition which comprises 100 parts by weight of (A) a resin comprising 1 to 99% by weight of (a-1) a styrenic polymer having the syndiotactic configuration and 99 to 1% by weight of (a-2) a thermoplastic resin and/or a rubbery elastomer; 0.005 to 5.0 parts by weight of (B) a phenolic antioxidant; and 0.005 to 5.0 parts by weight of (C) an antioxidant containing phosphorus.
[Polystyrenic Resin Composition 3]
A polystyrenic resin composition comprising 100 parts by weight of (A) a resin comprising 99.9 to 90.0% by weight of (a-1) a styrenic polymer having the syndiotactic configuration and 0.1 to 10.0% by weight of (a-3) a polymer exhibiting compatibility with or affinity for component (a-1) and having a polar group; 0.005 to 5.0 parts by weight of (B) a phenolic antioxidant; and 0.005 to 5.0 parts by weight of (C) an antioxidant containing phosphorus.
[Polystyrenic Resin Composition 4]
A polystyrenic resin composition which comprises 100 parts by weight of (A) a resin obtained by mixing 100 parts by weight of a resin comprising 1 to 99% by weight of (a-1) a styrenic polymer having the syndiotactic configuration and 99 to 1% by weight of (a-2) a thermoplastic resin and/or a rubbery elastomer with 0.1 to 10.0 parts by weight of (a-3) a polymer exhibiting compatibility with or affinity for component (a-1) and having a polar group; 0.005 to 5.0 parts by weight of (B) a phenolic antioxidant; and 0.005 to 5.0 parts by weight of (C) an antioxidant containing phosphorus.
[Polystyrenic Resin Compositions 1 to 4]
Above Polystyrenic resin compositions 1 to 4, wherein the phenolic antioxidant of component (B) is preferably represented by general formula (I) which is shown later; and the antioxidant containing phosphorus of component (C) is preferably represented by general formula (II) which is shown later.
[Polystyrenic Resin Composition 5]
A polystyrenic resin composition which comprises 100 parts by weight of the resin of component (A) described in any of 1 to 4, 0.005 to 5.0 parts by weight of (B) a phenolic antioxidant, 0.005 to 5.0 parts by weight of (C) an antioxidant containing phosphorus, and 0.005 to 5.0 parts by weight of (D) an antioxidant containing sulfur.
Above Polystyrenic resin composition 5, wherein the phenolic antioxidant of component (B) is preferably represented by general formula (I) which is shown later; the antioxidant containing phosphorus of component (C) is preferably represented by general formula (II) which is shown later; and the antioxidant containing sulfur of component (D) is preferably represented by general formula (III) which is shown later.
[Polystyrenic Resin Composition 6]
A polystyrenic resin composition which comprises 100 parts by weight of any of Polystyrenic resin compositions 1 to 5 and 1 to 350 parts by weight of (E) an inorganic filler.
[A Molded Article of a Polystyrenic Resin Composition]
A molded article which is prepared by using any of Polystyrenic resin compositions 1 to 6.
THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
The resin of component (A) used in the polystyrenic resin composition of the present invention comprises (a-1) a styrenic resin having the syndiotactic configuration as the essential component and at least one of (a-2) a thermoplastic resin and/or a rubbery elastomer and (a-3) a polymer exhibiting compatibility with or affinity for component (a-1) and having a polar group as the optional component. Therefore, one of components (a-2) and (a-3) alone may be comprised, or both may be comprised.
The syndiotactic configuration of SPS of component (a-1) means that the stereochemical structure has a highly syndiotactic configuration. In other words, phenyl groups and substituted phenyl groups of the side groups are alternately placed at the opposite positions with respect to the main chain formed with the ca
Hoke Veronica P.
Idemitsu Kosan Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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