Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-06-29
2002-09-17
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...
C524S141000, C524S145000
Reexamination Certificate
active
06451889
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flameproof thermoplastic resin composition. More particularly, the present invention relates to a flameproof thermoplastic resin composition that comprises a rubber modified styrene-containing resin as a base resin, a phenolic resin, a polyphenylene ether resin having a hindered phenolic structure and an aromatic phosphoric acid ester having a hindered phenolic structure.
BACKGROUND OF THE INVENTION
A rubber modified styrene-containing resin has a good processability, a high impact strength, and a good appearance. Accordingly, the resin has been widely applied to electrical appliances and office supplies. In case that a rubber modified styrene-containing resin is applied to a personal computer, facsimile, or the like, that emits heat, a property of flame retardancy should be given in the resin due to a combustibility. A widely known method for the flame retardancy is that halogen-containing compounds or antimony-containing compounds are added to a rubber modified styrene-containing resin to give the property of flame retardancy. Halogen-containing compounds used in above method are, for example, polybromodiphenyl ether, tetrabromobisphenol A, epoxy compounds substituted by bromine, and chlorinated polyethylene. An antimony trioxide and an antimony pentoxide are widely used as antimony-containing compounds. The flame retardancy method by applying halogen and antimony has such advantages as easy acquirement of the property of flame retardancy and no degradation of the physical properties. However, the disadvantages could be observed that the halogen-containing compound results in the corrosion of the mold itself by the hydrogen halide gases released during a molding process and is fatally harmful due to the toxic gases liberated in the case of fire. Especially, since a polybromodiphenyl ether, mainly used for a halogen-containing flame-retardant, can produce the toxic gases such as dioxin or difuran during combustion, a flame retardant which is not prepared with halogen-containing compound becomes the main concern in this field.
U.S. Pat. Nos. 4,692,488 and 5,204,394 disclose a compound that an aromatic phosphoric acid ester compound is applied to a blend of polycarbonate and acrylonitrile-styrene-butadiene resin, and polytetrafluoroethylene is added therein, so that the property of UL94 V-0 is acquired. On the other hand, the acquirement of the properties of V-0 or V-1 is difficult when the contents of polycarbonate is less than 60 parts by weight, due to the flame retardant characteristic itself of an aromatic phosphoric acid ester.
In addition, Japanese Patent Laid-open No. 7-48,491 discloses a flameproof thermoplastic resin, made of adding novolacs as phenolics and a phosphoric acid ester into a thermoplastic copolymer resin composed of a rubber copolymer and an aromatic vinyl monomer. According to the present inventors' appraisal, it is difficult to obtain a practical heat resistance because the property of UL94 V-1 or V-0 is difficult to acquire, and heat resistance is suddenly dropped. The practical heat resistance means the heat resistance applied in an electric equipment. In case of a monitor housing of computer, it should be kept at least 85° C. under 5 kg according to ASTM D-1525.
Accordingly, the present inventors have developed a resin composition with the good properties of flame retardancy and heat resistance, which comprises a rubber modified styrene-containing resin, a phenolic resin, a PPE resin having a hindered phenol structure and an aromatic phosphoric acid ester having a hindered phenol structure, and also the resin composition may further comprise a fluorine resin.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a thermoplastic resin composition which has a good property of flame-retardancy.
Another object of the present invention is to provide a flameproof thermoplastic resin composition which has a good characteristic of heat resistance.
A further object of the present invention is to provide a flameproof thermoplastic resin composition which does not contain a halogen-containing compound which causes the environmental pollution during the process or combustion of the resin.
Other objects and advantages of this invention will be apparent from the ensuing disclosure and appended claims.
SUMMARY OF THE INVENTION
A flameproof thermoplastic resin composition of the present invention comprises (A) 100 parts by weight of a rubber modified styrene-containing base resin composed of 20~100% by weight of a styrene-containing graft copolymer resin and 0~80% by weight of a styrene-containing copolymer resin; (B) 5~40 parts by weight of a phenolic resin; (C) 3~40 parts by weight of a PPE resin having a hindered phenolic structure; and (D) 5~30 parts by weight of an aromatic phosphoric acid ester having a hindered phenolic structure. The flameproof thermoplastic resin composition may further comprise 0.01~2.0 parts by weight of a fluorine resin to 100 parts by weight of rubber modified styrene-containing base resin.
DETAILED DESCRIPTION OF THE INVENTION
The flameproof thermoplastic resin compositions according to the present invention comprise (A) a rubber modified styrene-containing base resin composed of (a
1
) a styrene-containing graft copolymer resin and (a
2
) a styrene-containing copolymer resin, (B) a phenolic resin, (C) a PPE resin having a hindered phenolic structure and (D) an aromatic phosphoric acid ester having a hindered phenolic structure. The resin composition may further comprise (E) a fluorine resin.
Generally, when a rubber modified styrene-containing resin such as ABS is burned, a char is not produced due to a decomposition and a vaporization in most parts. Therefore, in case of not adding a halogen which imparts an effect of flame retardancy in gas phase, it is very difficult to obtain the property of flame-retardancy. Japanese Patent Laid-open No. 7-48491 discloses a flameproof composition which does not contain a halogen-containing compound, wherein a phenolic resin and a phosphoric acid ester was used as a flame-retardant. It was found that in order to obtain a good property of flame-retardancy, a phenolic resin and a phosphoric acid ester as a flame retardant should be added a lot. However, in this case, the heat resistance of the resin composition may be dropped suddenly.
In order to maintain heat resistance of more than 85° C., an appropriate amount of a phenolic resin and a phosphoric acid ester should be employed therein.
The present inventors have made it possible to make a flameproof resin composition by means of mixing and adding a phenolic resin, a polyphenylene ether resin having a hindered phenolic structure, and an aromatic phosphoric acid ester having a hindered phenolic structure to the rubber-modified styrene-containing resin. Therefore, a good property of flame-retardancy as well as a good improvement of heat resistance were obtained, and the resin composition has heat resistance of more than 85° C. and a physical property of more than UL94 V-1.
The detailed descriptions of components of the resin composition according to the present invention are as follows:
(A) Rubber modified Styrene-containing Base Resin
A rubber modified styrene-containing base resin means a styrene-containing graft copolymer resin such as ABS, and the graft copolymer resin may contain a styrene-containing copolymer resin such as SAN.
A rubber modified styrene-containing resin is that a rubber phase copolymer is dispersed and existed in the form of particles in a matrix, made of aromatic vinyl copolymers. The resin is prepared by adding an aromatic vinyl monomer and a vinyl-containing monomer, which can be polymerized therewith, in the presence of a rubber phase polymer. Such rubber-modified styrene-containing resin is prepared by a known method such as emulsion polymerization, suspension polymerization or bulk polymerization, and is conventionally produced by means of mixed extrusion with a styrene-containing graft copolymer resin and a styrene-containing copolymer
Jang Bok-nam
Kim Se-jong
Lee Gyu-cheol
Cheil Industries Inc.
Szekely Peter
Tungol Maria Parrish
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