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...
Reexamination Certificate
1999-08-02
2002-09-10
Szekely, Peter (Department: 1714)
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...
C264S331160, C524S127000, C524S141000, C524S410000, C524S411000, C524S412000, C525S067000, C525S148000, C525S227000, C526S329700
Reexamination Certificate
active
06448324
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flame-retardant polycarbonate resin composition and its blow moldings. More precisely, it relates to a flame-retardant polycarbonate resin composition having the advantage of flame retardancy, thermal stability and draw-down resistance and cable of being formed into large-size moldings through blow molding, vacuum molding or pneumatic compression molding, and also to blow moldings of the composition.
2. Description of the Related Art
As having the advantages of impact resistance, heat resistance and good electric properties, polycarbonate resins have many applications in various fields of, for example, office automation appliances, electric and electronic appliances for industrial and household use, car parts and building materials. However, there are some problems with polycarbonate resins in that they require high molding and working temperatures and their melt fluidity is low. As requiring relatively high molding and working temperatures, polycarbonate resins, especially those containing various additives are often problematic in that their thermal stability is poor while they are molded and worked and that their moldings could not exhibit their good properties. As a rule, polycarbonate resins are self-extinguishable. However, some of their applications to office automation appliances, electric and electronic appliances for industrial and household use and others require high-level flame retardancy. To meet the requirement, various flame retardants are added to polycarbonate resins.
In general, polycarbonate resins are formed into moldings of office automation appliances, electric and electronic appliances for industrial and household use and others, through injection molding, and such their moldings are required to be lightweight and thin-walled from the viewpoint of resources saving. However, injection molding of polycarbonate resins to give thin-walled products is naturally limited because of the limited melt viscosity of the resins and of the intended rigidity of the molded products. For these reasons, blow molding of polycarbonate resins is tried for producing lightweight moldings of those appliances and components. However, in order to ensure high-level flame retardancy of polycarbonate resins, a relatively large amount of a flame retardant must be added to the resins. In particular, polymer alloys of polycarbonate resin and rubber-like polymer-modified styrenic resin that are intended to have both good moldability and good impact resistance are problematic in that their blow moldability is poor and stable production of blow moldings of such polymer alloys is impossible.
For improving the blow moldability of polycarbonate resins, it is known that polycarbonate resins having a branched structure are favorable to blow molding. However, depending on the size and the shape of the moldings to be formed therefrom, such polycarbonate resins having a branched structure are often still problematic in that their melt fluidity, blow moldability and pinch-off strength are not satisfactory.
On the other hand, in these days, blow molding is being tried, in place of injection molding, for producing lightweight and thin-walled moldings of covers or housings for office automation appliances such as duplicators and others, from the viewpoint of resources saving. However, those moldings generally have a relatively large surface area and substantially differ from ordinary blow moldings having a hollow inner space such as containers. Specifically in producing them, ribs must be formed for which a parison is welded between the surface parts, so as to prevent the depression in the strength and the rigidity of the thin-walled moldings. Therefore, in producing these moldings, not only their pinch-off strength but also the weld strength of the ribs as welded inside them is needed. In particular, when a relatively large amount of a flame retardant is added to polycarbonate resins so as to increase the flame retardancy of the resins, a rubber-like polymer-modified styrenic resin is added thereto thereby to ensure the impact resistance and other physical properties of the moldings of the resin compositions. The polycarbonate resin compositions comprising them are desired to have good blow moldability.
Compositions of polycarbonate resins to which are added styrenic resins such as acrylonitrile-butadiene-styrene resins (ABS resins), acrylonitrile-styrene resins (AS resins) and the like for the purpose of improving the melt fluidity of the resin compositions are known as polymer alloys, and have many applications typically in the field of injection moldings as having good heat resistance and impact resistance. Of their applications, where such polycarbonate resin compositions are used for office automation appliances, electric and electronic appliances and others, they are required to have high flame retardancy of not lower than a predetermined level so as to ensure and increase the safety of their moldings.
To meet the requirements as above, various methods have heretofore been proposed. Concretely, JP-A-61-55145 discloses a thermoplastic resin composition comprising (A) an aromatic polycarbonate resin, (B) an ABS resin, (C) an AS resin, (D) a halogen compound, (E) a phosphate, and (F) a polytetrafluoroethylene component. JP-A-2-32154 discloses a molding polycarbonate composition with high flame retardancy and high impact resistance, comprising (A) an aromatic polycarbonate resin, (B) an ABS resin, (C) an As resin, (D) a phosphate, and (E) a polytetrafluoroethylene component. JP-A-8-239565 discloses a polycarbonate resin composition comprising (A) an aromatic polycarbonate, (B) an impact-resistant polystyrene resin with rubber-like elasticity, (D) a halogen-free phosphate, (C) a core/shell type, grafted rubber-like elastomer, and (E) talc.
These are all to improve the melt fluidity and therefore the moldability of polycarbonate resins, and to improve the impact resistance and the flame retardancy of the moldings of polycarbonate resins. As having such improved properties, the polycarbonate resin compositions proposed are formed into various practicable moldings. However, they are targeted to injection moldings, and it is difficult to directly apply them to blow moldings. In particular, it is difficult to directly apply them to relatively large-sized moldings or to blow moldings having nearly tabular ribs such as those mentioned above.
In order to improve the blow moldability of polycarbonate resins, various methods have been proposed. For example, (1) JP-A-1-268761 discloses a method of mixing an engineering resin such as a polycarbonate resin or the like with an acrylic polymer having a weight-average molecular weight of at least about 500,000; (2) JP-B-5-422 discloses use of a copolymer of methyl methacrylate and a vinylic monomer as prepared through emulsion polymerization in the presence of a specific emulsifier, as a working promoter for thermoplastic resins; and (3) JP-B-8-6022 discloses a thermoplastic resin composition comprising a polycarbonate resin or a polybutylene terephthalate resin, and containing a copolymer of an alkyl methacrylate and an alkyl acrylate having a specific relative viscosity, and carbon black having a specific relative surface area and a specific degree of oil absorption. However, the composition in (3) is problematic in that it indispensably requires carbon black and could not be formed into white moldings, and therefore its applications are limited. In addition, none of those (1) to (3) refers to the flame retardancy of resin compositions.
On the other hand, some flame-retardant resin compositions for blow moldings have been proposed. For example, (4) JP-A-9-310011 discloses a resin composition comprising an aromatic polycarbonate resin, a styrene-acrylonitrile resin, a phosphate serving as a flame retardant, and ultra-fine grains of anhydrous silica; and (5) JP-A-10-158497 discloses a resin composition for blow moldings, comprising a polycarbonate resin, an ABS resin, a SAN
Hara Kouichi
Mitsuta Naoki
Nodera Akio
Idemitsu Petrochemical Co. Ltd.
Szekely Peter
LandOfFree
Flame-retardant polycarbonate resin composition and its blow... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flame-retardant polycarbonate resin composition and its blow..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flame-retardant polycarbonate resin composition and its blow... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2909684