Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-06-22
2002-10-08
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S001000, C524S140000, C524S141000, C524S150000, C524S151000
Reexamination Certificate
active
06462112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel flame-retarded resin composition, and more particularly to a flame-retarded ABS resin composition which does not generate a corrosive or poisonous gas by decomposition of the resin composition at the time of molding or burning, and which has a good processing property to produce a molded article having a high flame retardancy, good mechanical properties and a resistance to hydrolysis.
2. Description of the Related Art
Thermoplastic resins have excellent properties in that they can be manufactured at a comparatively low cost and they can be easily molded, so that they are used in every field of industry. Especially, ABS resins have excellent mechanical properties, heat resistance, processing property and the like, so that ABS resins are widely used for electric and electronic components, automobile components or the like. However, the thermoplastic resins are generally flammable and, for their use, it is necessary to make the resins flame-retarded by adding a flame-retarder or a flame-retarded auxiliary to the thermoplastic resins. In recent years, more excellent properties (flame retardancy, mechanical properties, heat resistance, electrical insulating property and the like) are sought for in accordance with the diversification of use or increase in scale of the thermoplastic resins.
In order to give flame-retardancy to thermoplastic resins, there has been adopted a method of adding a halogen-type flame-retarder in preparing resin compositions. However, this halogen-type flame-retarder, while giving a flame-retardancy to resins, may possibly generate a hydrogen halide by thermal decomposition at the time of molding to corrode a metal part in a metal mold, molding machine, peripheral apparatus, electric and electronic component or the like. A method for collecting such a corrosive gas can be considered. However, it requires a special equipment. Also, a lot of smoke is generated at the time of burning, and, since the hydrogen halide is poisonous, it not only degrades a working environment but also produces adverse effects on human beings at the time of burning such as a fire. Therefore, in recent years, non-halogen-type flame-retarders are used in many cases.
As the non-halogen-type flame-retarders, inorganic metal compounds such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide or basic magnesium carbonate are used. Especially, magnesium hydroxide has a high temperature of decomposition accompanied by dehydration and is excellent in preventing the generation of smoke at the time of burning, so that magnesium hydroxide is widely used for practical applications. However, in order to produce a sufficient flame-retarded effect, magnesium hydroxide must be added at a large amount and it considerably decreases the inherent properties of the resins, especially the mechanical properties.
As the non-halogen-type flame-retarders other than inorganic metal compounds, organic phosphorus compounds are widely used. Representative organic phosphorus compounds include low molecular weight phosphates such as trimethyl phosphate and triphenyl phosphate.
Japanese Unexamined Patent Publication No. SHO 61(1986)-291644 discloses that flame retardancy can be given to ABS resins by adding a resol-type phenolic resin and red phosphorus to the resins.
Also, Japanese Unexamined Patent Publications No. HEI 6(1994)-248160 and No. HEI 7(1995)-48491 disclose a technique for giving flame retardancy to ABS resins without lowering their impact resistance of the resin, by adding a phenolic resin and an organic phosphorus compound to the resin.
However, the resin compositions disclosed in these Publications have problems in terms of their heat resistance, although they are excellent in flame retardancy and mechanical properties. Especially, it is difficult to use them for purposes that require severe specifications in heat resistance (for example, components that are used in locally heated parts such as an engine part of an automobile or a heat transfer roller of a copying machine).
Moreover, since the organic phosphorus compounds give not only flame retardancy but also plasticity to the resins, there has been a problem that heat deformation temperature or softening temperature of the resins considerably decreases. It is known in the art that the electric property and the flame retardancy of flame-retarded ABS resin compositions are deteriorated by water absorption when the resin compositions are used under severe conditions at a high temperature and high humidity, for example, in various electric and electronic components such as a television set or personal computer, or in automobile components.
SUMMARY OF THE INVENTION
The present invention has been made in view of these circumstances. The present inventors have made an eager research to solve the above-mentioned problems and found out that a resin composition having a high flame retardancy, excellent mechanical properties, heat resistance and hydrolysis resistance in good balance can be produced by adding a specific aromatic phosphate and novolak-type phenolic resin to an ABS resin, thus completing the present invention.
The purpose of the present invention is to provide a flame-retarded ABS resin composition which does not contain a halogen atom and does not generate a corrosive or poisonous gas at the time of molding or burning, which has high flame retardancy and mechanical properties with low volatility, and has excellent resistance to hydrolysis without lowering the electric properties by water absorption or blistering.
Accordingly, the present invention provides a flame-retarded resin composition containing: (A) an ABS resin; (B) an aromatic phosphate having a melting point of 80° C. or more and being represented by the following general formula (I):
wherein R
1
to R
4
are, the same or different, a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, excluding the case where R
1
to R
4
are all hydrogen atoms; X is a bond, —CH
2
—, —C(CH
3
)
2
—, —S—, —SO
2
—, —O—, —CO— or —N═N—; n is an integer of 0 or 1; and m is an integer of 0 to 5; and (C) a novolak-type phenolic resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The “ABS resin(s)” of the component (A) to be used in the present invention represents a resin formed from three kinds of monomers, i.e. acrylonitrile, butadiene, and styrene, as principal materials. However, a desired site of the above-mentioned monomers may be substituted with a specific group for improvement of the property of the resin to be produced.
The ABS resins may be specifically 1) a resin obtained by graft copolymerization of an aromatic vinyl compound (such as styrene) and a vinyl monomer (such as acrylonitrile) copolymerizable with the aromatic vinyl compound, to a rubbery polymer (such as polybutadiene or styrene-butadiene copolymer rubber) or 2) a polymer blend obtained by blending a vinyl copolymer (such as styrene-acrylonitrile copolymer) formed from an aromatic vinyl compound and a vinyl monomer copolymerizable with the aromatic vinyl compound, with a rubbery polymer (such as acrylonitrile-butadiene copolymer rubber). Among these two, the latter one is preferable. The ratio of blending the vinyl copolymer and the rubbery polymer in the polymer blend is usually 30 to 40:60 to 70 (wt. %).
The aromatic vinyl compound in the component (A) may be, for example, styrene, &agr;-methylstyrene, or paramethylstyrene. Among these, styrene is particularly preferable.
The vinyl monomer copolymerizable with the aromatic vinyl compound may be alkyl (meth)acrylate such as methyl acrylate, ethyl acrylate or methyl methacrylate; (meth)acrylic acid such as acrylic acid or methacrylic acid; vinyl cyanide monomer such as acrylonitrile or methacrylonitrile; &agr;,&bgr;-unsaturated carboxylic acid such as maleic anhydride; maleimide monomer such as N-phenylmaleimide, N-(methylphenyl)maleimide, N-cyclohexylmaleimide or N-methylmaleimide; or glycidyl monomer such as glycidyl (meth)acrylate.
Among the above-mentioned vi
Daihachi Chemical Industry Co. Ltd.
Greenblum & Bernstein P.L.C.
Szekely Peter
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