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
2001-07-06
2003-02-18
Sanders, Kriellion A. (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...
C524S095000, C524S116000, C524S119000, C524S122000, C524S413000, C524S433000, C524S436000, C524S437000, C524S432000, C524S443000, C524S444000, C524S494000
Reexamination Certificate
active
06521689
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flame-retardant aromatic polyamide resin composition and moldings.
BACKGROUND ART
Aromatic polyamide resins are excellent in heat resistance, mechanical properties, molding processability, chemical resistance and the like and are widely used for automotive parts, electric and electronic parts, machine parts, etc. When aromatic polyamide resins are used in these applications, a flame retardant needs to be added to the aromatic polyamide resin in order to impart flame retardancy to the resin for prevention of ignition due to the generation of heat. Especially, when these resins are used for electric and electronic parts, the resins are required to have a flame retardancy as high as V-0 (a level of flame retardancy at which combustion does not continue for longer than a specific period of time and there occurs no dripping of molten resin which ignites cotton) according to UL Standard (Underwriters Laboratories, Inc., Standard for Tests for Flammability of Plastics Materials).
Various flame-retardant aromatic polyamide resin compositions comprising an aromatic polyamide resin and a flame retardant have been proposed and include, for example, a composition comprising an aromatic polyamide resin, brominated polystyrene and antimony oxide (Japanese Unexamined Patent Publications Nos. 263985/1994 and 263986/1994); a composition comprising an aromatic polyamide resin, brominated polystyrene, magnesium hydroxide and the like (Japanese Unexamined Patent Publication No. 196875/1995); a composition comprising an aromatic polyamide resin and a halogen-substituted phosphazene compound (Japanese Unexamined Patent Publications Nos. 133470/1974 and 132149/1974), etc.
However, the halogen compound which is incorporated as the flame retardant into these compositions thermally decomposes during molding of resins, and generates hydrogen halide, unavoidably resulting in corrosion of molds, and in degradation and discoloration of the resin. When resin moldings are burned by a fire or the like, hydrogen halide and the like raise another problem of giving off gases and smoke which are harmful to organisms.
On the other hand, flame-retardant aromatic polyamide resin compositions which do not contain a halogen compound are known and include, for example, a composition comprising an aromatic polyamide resin, an inorganic filler, red phosphorus, melamine cyanurate and the like (Japanese Unexamined Patent Publication No. 161848/1980); a composition comprising an aromatic polyamide resin, a phenolic resin, an aldehyde resin, red phosphorus, a filler and the like (Japanese Unexamined Patent Publications Nos. 25956/1979 and 80357/1979) and so on.
However, these compositions entail a problem that because of red phosphorus present therein, the moldings produced from the composition are inevitably markedly colored and are difficult to use for the above-mentioned purposes. Japanese Unexamined Patent Publication Nos. 183864/1997 discloses a composition comprising an aromatic polyamide resin, a phosphorylamide compound, cyanuric acid and the like. The disclosed composition, although free of both the halogen compound and red phosphorus, gives molded products which are unsatisfactory in flame retardancy and mechanical properties.
Halogen-free phosphate compounds are widely used as a flame retardant for thermoplastic resins. Various flame-retardant resin compositions containing such phosphate compound are proposed. Known as halogen-free phosphate compounds are, for example, resorcinol-bis(diphenyl phosphate), hydroquinone-bis(diphenyl phosphate), bisphenol-A-bis(diphenyl phosphate), bisphenol-S-bis(diphenyl phosphate), resorcinol-bis(dixylyl phosphate), hydroquinone-bis(dixylyl phosphate), bisphenol-A-bis(ditolyl phosphate), bisphenol-A-bis(dixylyl phosphate), bisphenol-S-bis(dixylyl phosphate), etc. However, the resin compositions containing these phosphate compounds can not sufficiently prevent dripping of molten resin when moldings of the composition are burned. Consequently even if these phosphate compounds are incorporated into a resin composition, it is impossible to obtain a flame-retardant composition and moldings which have flame retardancy as high as V-0 in UL Standard.
Furthermore, known as a flame retardant is a crosslinked phosphazene compound (Japanese Unexamined Patent Publication No. 181429/1999) in which at least one phosphazene compound selected from the group consisting of a cyclic phenoxyphosphazene compound represented by the formula (1)
wherein m is an integer of 3 to 25 and Ph is a phenyl group and a linear phenoxyphosphazene compound represented by the formula (2)
wherein X
1
represents a group —N═P(OPh)
3
or a group —N═P(O)OPh, Y
1
represents a group —P(OPh)
4
or a group —P(O)(OPh)
2
, n is an integer of 3 to 10000 and Ph is as defined above
is/are crosslinked with at least one crosslinking group selected from the class consisting of o-phenylene group, m-phenylene group, p-phenylene group and bisphenylene group represented by the formula (3)
wherein A is —C(CH
3
)
2
—, —SO
2
—, —S— or —O— and a is 0 or 1;
wherein
(i) each of the crosslinking groups is interposed between the two oxygen atoms left after the elimination of phenyl groups from the phosphazene compound; and
(ii) the amount of the phenyl groups in the crosslinked compound is 50 to 99.9% based on the total amount of the phenyl groups in the phosphazene compound represented by the formula (1) and/or the phosphazene compound represented by the formula (2). The foregoing crosslinked phosphazene compound has a free hydroxyl group(s) in the molecule. The process for preparing the crosslinked phosphazene compound which is disclosed in Publication No. 181429/1999 gives a crosslinked phosphazene compound in which a hydroxyl group(s) is/are unavoidably left, the hydroxyl group(s) being derived from an alkali metal salt of aromatic dihydroxy compound used as the raw material. The reason therefor is as follows.
According to the research by the present inventors, it was found that the alkali metal salt of aromatic dihydroxy compound shows an exceedingly lower reactivity in a reaction with the dichlorophosphazene compound than the alkali metal salt of phenol. Stated more specifically, when a dichlorophosphazene compound is mixed with an alkali metal salt of phenol with heating, there is produced a phenoxyphosphazene in which the chlorine atom is substituted with a phenoxy group. On the other hand, when a dichlorophosphazene compound is mixed with an alkali metal salt of aromatic dihydroxy compound with heating, substantially no reaction occurs in which the chlorine atom is substituted with a phenoxy group.
Consequently, according to the process disclosed in Japanese Unexamined Patent Publication No. 181429/1999 (in which a dichlorophosphazene compound is reacted with an alkali metal salt of phenol and an alkali metal salt of aromatic dihydroxy compound), a great difficulty is entailed in completely substituting the chlorine atom in the dichlorophosphazene compound with two OM groups (M=alkali metal) of the alkali metal salt of aromatic dihydroxy compound. Accordingly the OM groups remaining unreacted with the chlorine atom are converted into OH groups, with the result that a phenoxyphosphazene compound having a hydroxyl group is produced.
The crosslinked phosphazene compound disclosed in Japanese Unexamined Patent Publication No. 181429/1999 has the following defect as the flame retardant due to free hydroxyl groups in the molecule.
When a resin composition prepared by incorporating the crosslinked phosphazene compound disclosed in Japanese Unexamined Patent Publication No. 181429/1999 into a resin is stored for a prolonged period of time, the moldings molded from the composition exhibit a low flame retardancy and impaired mechanical properties.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a flame-retardant aromatic polyamide resin composition which is free of a halogen compound so that no hydrogen halide is generated due to heat decom
Kameshima Takashi
Nakano Shinji
Nishioka Yoichi
Tada Yuji
Takase Hiroyuki
Knobbe Martens Olson & Bear LLP
Otsuka Chemical Co. Ltd.
Sanders Kriellion A.
LandOfFree
Flame-retardant aromatic polyamide resin composition and... 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 aromatic polyamide resin composition and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flame-retardant aromatic polyamide resin composition and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3116293