Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-10-16
2002-12-24
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06498228
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a flame-retardant polycarbonate resin composition, precisely to flame-retardant polycarbonate resin composition and moldings having the advantages of impact resistance, in-line heat stability, aging resistance and recyclability. The invention also relates to flame-retardant polycarbonate resin composition and moldings having the advantages of impact resistance, weld strength and good appearance with few weld lines appearing on their surfaces, and capable of being well colored in dark color, and to flame-retardant polycarbonate resin composition and moldings having the advantages of flame retardancy, impact resistance, stable physical properties even in high-temperature and high-humidity atmospheres, and improved recyclability.
BACKGROUND 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, OA (office automation) appliances, information and communication appliances, other electric and electronic appliances for industrial use and household use, automobile parts and building materials. As a rule, polycarbonate resins are self-extinguishable. However, in some fields of typically OA appliances, information and communication appliances, and other electric and electronic appliances for industrial use and household use, required are polycarbonate resins having more improved flame retardancy.
For improving the flame retardancy of polycarbonate resins, halogen-containing flame retardants such as bisphenol A halides and halogenated polycarbonate oligomers have been used along with a flame retardation promoter such as antimony oxide, as their flame-retarding ability is good. However, with the recent tendency toward safety living and environmental protection from discarded and incinerated wastes, the market requires flame retardation with non-halogen flame retardants. As non-halogen flame retardants, phosphorus-containing organic flame retardants, especially organic phosphate compounds may be added to polycarbonate resin compositions, for which various methods have been proposed. Such flame retardants, organic phosphate compounds serve also as a plasticizer, and polycarbonate resin compositions containing them exhibit excellent flame retardancy.
There are some problems with polycarbonate resins in that they require high molding and working temperatures and their melt fluidity is low. Therefore, the molding temperature for polycarbonate resins is relatively high, and when various additives are added to the resins, there occurs still another problem in that the thermal stability of the molding resins is lowered and that the resins could not sufficiently exhibit their properties. On the recent market, moldings for parts and housings of electric and electronic appliances such as duplicators, facsimiles and telephones are required to have complicated shapes with local projections or depressions for, for example, ribs or bosses and to have openings, and are also required to be lightweight and thin-walled from the viewpoint of resources saving. For these reasons, desired are polycarbonate resin compositions having improved melt fluidity, or that is, having improved injection moldability. Various polycarbonate resin compositions having enhanced moldability have heretofore been proposed, to which are added (rubber-modified) styrenic resins in consideration of the physical properties such as impact resistance of the moldings of the compositions.
Compositions of polycarbonate resins to which are added non-halogen phosphate compounds serving as a flame retardant, and those to which are added (rubber-modified) styrenic resins such as acrylonitrile-butadiene-styrene resins (ABS resins), rubber-modified polystyrene resins (HIPS resins) or acrylonitrile-styrene resins (AS resins) for increasing the melt fluidity of the compositions, are known as polymer alloys, and have many applications in the field of various moldings as having good heat resistance and impact resistance.
The ABS resin-containing compositions have improved melt fluidity and impact resistance, but their toughness is often poor. The rubber-modified polystyrene resin (HIPS)-containing compositions also have improved melt fluidity and impact resistance. As compared with the ABS resin-containing compositions, the HIPS-containing compositions have higher toughness if the rubber content of HIPS therein is lowered. HIPS having a lowered rubber content does not lower the toughness and the heat resistance of the resin compositions containing it, but lowers the impact resistance thereof. This is another problem with HIPS.
In order to make polycarbonate resins or their compositions containing a (rubber-modified) styrenic resin and having good melt fluidity have good flame retardancy by adding thereto a phosphate compound, a relatively large amount of the compound must be added to them. Though its flame-retarding ability is good, the phosphate compound often cause some problems when added to polycarbonate resins or their compositions. For example, it is said that phosphate compounds adhere to the molds used for molding resins or resin compositions containing them, and, in addition, phosphate compounds lower the impact strength of resin moldings or yellows them when the resin moldings are kept heated, or left in high-temperature high-humidity atmospheres, or recycled. A composition comprising a polycarbonate resin, a rubber-modified polystyrene resin and a phosphate compound has good flame retardancy and impact resistance, which, however, depends on the rubber content of the rubber-modified polystyrene resin in the composition. When the heat resistance and the toughness of the resin composition is kept on a desired level, the impact resistance thereof is often insufficient. The flame-retardant polycarbonate resin compositions mentioned above are molded in a mode of injection molding, and their moldings are much used for housings of OA appliances, etc. In general, the moldings are colored in dark color such as gray or black, for which is used a colorant comprising, as the essential ingredient, carbon black.
Many of the moldings are thin-walled and have complicated shapes, and they are welded, depending on the shape of the molds used. When welded, the appearance of the welded part is often poor and the weld strength is of ten low. The problem is especially serious with resin compositions comprising a polycarbonate resin and a rubber-modified polystyrene resin and containing a phosphate compound.
When a phosphate compound is added to polycarbonate resins for making them have flame retardancy, it is generally liquid at room temperature or has a low melting point. However, a relatively large amount of such a phosphate compound must be added to polycarbonate resins for making them have flame retardancy, it is often problematic in that the phosphate compound added thereto blooms resin moldings and lowers the heat resistance and the impact resistance of resin moldings. To solve the problem with such a phosphate compound that blooms resin moldings and lower the heat resistance of resin moldings, for example, Japanese Patent Laid-Open No. 228426/1994 discloses a method of combining (A) a polyphenylene-ether resin or a polycarbonate resin, (B) a high-viscosity, alkyl-substituted aromatic phosphate compound having a specific structure, and (C) a triphenyl phosphate.
Japanese Patent Laid-Open No. 179715/1995 discloses a flame-retardant resin composition comprising (A) from 1 to 99 parts by weight of a polycarbonate resin, (B) from 1 to 99 parts by weight of a rubber-reinforced resin, and (C) from 0.1 to 30 parts by weight, relative to 100 parts by weight of (A) and (B), of an organic phosphorus compound having a melting point of not lower than 120° C. Japanese Patent Laid-Open No. 12867/1996 discloses a thermoplastic resin composition comprising a resin mixture of from 50 to 98% by weight of (A) an aromatic polycarbonate and from 2 to 50% by weight of (B) an ABS resin and/or (C) an AS resin, an
Kuze Shigeki
Mitsuta Naoki
Murakami Tsuyoshi
Nodera Akio
Boykin Terressa M.
Idemitsu Petrochemical Co. Ltd.
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