Stock material or miscellaneous articles – Structurally defined web or sheet – Physical dimension specified
Reexamination Certificate
1999-10-12
2001-11-27
Buttner, David J. (Department: 1712)
Stock material or miscellaneous articles
Structurally defined web or sheet
Physical dimension specified
C524S127000, C524S140000, C524S141000, C524S267000, C525S393000, C525S397000
Reexamination Certificate
active
06322882
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyphenylene ether resin composition. More specifically, the present invention relates to a polyphenylene ether resin composition having superior heat resistance and flame resistance. The polyphenylene ether resin composition of the present invention can be used particularly suitably as a flame-resisting insulation sheet for electric and electronic parts without use of any halogen-containing flame retardant or any halogen-containing anti-dripping agent as an essential component.
BACKGROUND OF THE INVENTION
A flame-resisting insulation sheet has a thickness of from about 0.1 to 0.5 mm and is required to have superior heat resistance as well as superior flame-resisting and insulation properties. As such a flame-resisting insulation sheet, a polyvinyl chloride resin-made sheet has been used extensively. However, a flame-resisting insulation sheet comprising no halogen has been increasingly required, because of an environmental problem due to the influence of halogen contained in the resin. In addition, a thin sheet such as a flame-resisting insulation sheet, when burned, easily causes an undesirable phenomenon such that a kindling piece of the sheet drips, the phenomenon being hereinafter referred to as “dripping phenomenon”. In this regard, a halogen-free sheet causes the dripping phenomenon more easily than a halogen-containing sheet.
As a technique to improve the dripping phenomenon of a polyphenylene ether resin, for example, U.S. Pat. Nos. 4,107,232, 4,332,714 and 4,355,126 disclose a combination use of polyfluoroethylene. Each of the references referred to above is incorporated herein by reference in its entirety.
However, there is left an environmental problem, because polyfluoroethylene also contains a halogen (fluorine) like a polyvinyl chloride resin.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a polyphenylene ether resin composition having superior heat resistance and flame resistance, which composition comprises neither a halogen-containing flame retardant nor a halogen-containing anti-dripping agent as an essential or mandatory component.
The present inventors have undertaken extensive studies relating to both the heat-resisting and flame-resisting properties of polyphenylene ether resin compositions. As a result, it has been found that a resin composition comprising a polyphenylene ether resin, a phosphoric ester and dispersed substances having a specific size can meet said object, and thereby the present invention has been obtained.
The present invention provides a polyphenylene ether resin composition comprising:
(i) a polyphenylene ether resin;
(ii) a phosphoric ester; and
(iii) a dispersed substance having an aspect ratio of not less than about 2.
The present invention also provides a flame-resisting insulation sheet containing the above-mentioned polyphenylene ether resin composition.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
DETAILED DESCRIPTION OF THE INVENTION
The term “polyphenylene ether resin” used in the present invention means a homopolymer resin or a copolymer resin obtained by oxidation polymerizing at least one phenol compound represented by the following formula (I) with oxygen or an oxygen-containing gas with the aid of an oxydative coupling catalyst,
wherein R
1
, R
2
, R
3
, R
4
and R
5
are independently of one another a hydrogen atom, a halogen atom, a hydrocarbon group or a substituted hydrocarbon group, provided that one of them is always a hydrogen atom.
Examples of R
1
, R
2
, R
3
, R
4
and R
5
in the formula (I) are hydrogen, chlorine, bromine, fluorine, iodine, methyl, ethyl, n- or iso-propyl, pri-, sec- or t-butyl, chloroethyl, hydroxyethyl, phenylethyl, benzyl, hydroxymethyl, carboxyethyl, methoxycarbonylethyl, cyanoethyl, phenyl, chlorophenyl, methylphenyl, dimethylphenyl, ethylphenyl and allyl.
Examples of the phenol compound represented by the formula (I) are phenol, o-, m- or p-cresol, 2,6-, 2,5-, 2,4- or 3,5-dimethylphenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2,6-diethylphenol, 2-methyl-6-ethylphenol, 2,3,5-, 2,3,6- or 2,4,6-trimethylphenol, 3-methyl-6-t-butylphenol, thymol and 2-methyl-6-allylphenol. Among these phenol compounds, 2,6-dimethylphenol, 2,6-diphenylphenol, 3-methyl-6-t-butylphenol and 2,3,6-trimethylphenol are preferred.
The phenol compound represented by the formula (I) may be copolymerized with a polyhydric aromatic compound such as bisphenol-A, tetrabromobisphenol-A, resorcinol, hydroquinone and novolak resins to prepare a copolymer. In the present invention, the copolymer is also contained in the polyphenylene ether resin according to the present invention.
The oxidative coupling catalyst used for the oxidative (co)polymerization of said phenol compound is not particularly limited, and any catalyst having a polymerizing ability can be used. As a process for oxidatively (co)polymerizing the phenol compound to produce the polyphenylene ether resin, there are exemplified those disclosed in, for example, U.S. Pat. Nos. 3,306,874, 3,306,875 and 3,257,357, Japanese Patent Publication (JP-B) No. 52-17880, and Japanese Patent Application Kokai (JP-A) Nos. 50-51197 and 1-304119. Each of the references referred to above is incorporated herein by reference in its entirety.
Specific examples of the polyphenylene ether resin used in the present invention are poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-propyl-1, 4-phenylene ether), poly(2, 6-dipropyl-1, 4-phenylene ether), poly(2-ethyl-6-propyl-1,4-phenylene ether), poly(2,6-dibutyl-1,4-phenylene ether), poly(2,6-dipropenyl-1,4-phenylene ether), poly(2,6-dilauryl-1,4-phenylene ether), poly(2,6-diphenyl-1,4-phenylene ether), poly(2,6-dimethoxy-1,4-phenylene ether), poly(2,6-diethoxy-1,4-phenylene ether), poly(2-methoxy-6-ethoxy-1,4-phenylene ether), poly(2-ethyl-6-stearyloxy-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2-methyl-1,4-phenylene ether), poly(2-ethoxy-1,4-phenylene ether), poly(3-methyl-6-t-butyl-1,4-phenylene ether), poly(2,6-dibenzyl-1,4-phenylene ether) and copolymers of every description containing a number of the repeating units constituting the above-exemplified resins.
Further, a copolymer of a multi-substituted phenol such as 2,3, 6-trimethylphenol and 2,3,5, 6-tetramethylphenol with a 2-substituted phenol such as 2,6-dimethylphenol is also contained in the polyphenylene ether resin according to the present invention.
Among the polyphenylene ether resins exemplified above, preferred are poly(2,6-dimethyl-1,4-phenylene ether) and a copolymer of 2,6-dimethylphenol with 2,3,6-trimethylphenol.
The polyphenylene ether resin used in the present invention may be a graft copolymer obtained by grafting the above-mentioned (co)polymer with a styrene compound such as styrene, &agr;-methylstyrene, p-methylstyrene and vinyltoluene, and such a graft copolymer is also contained in the polyphenylene ether resin according to the present invention.
With respect to the polyphenylene ether resin used in the present invention, those having an intrinsic viscosity of from about 0.3 to 0.7 dl/g, preferably from about 0.36 to 0.65 dl/g, more preferably from about 0.40 to 0.6 dl/g, measured in chloroform at 30° C. are preferred. When the intrinsic viscosity is too low, it may be difficult to attain no-dripping(i.e. to cause no dipping phenomenon) at the time of combustion, and when it is too high, the polyphenylene ether resin composition in accordance with the present invention may be deteriorated in its molding processability
Birch & Stewart Kolasch & Birch, LLP
Buttner David J.
Sumitomo Chemical Company Limited
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