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
2002-03-12
2003-09-30
Seidleck, James J. (Department: 1711)
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
active
06627690
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a flame-retardant polyester resin composition, molded products thereof and a molding method therefor and, more specifically, to a flame-retardant polyester resin composition which has excellent heat resistance, flame retardancy and moldability, molded products thereof and a molding method therefor.
PRIOR ART
Polyester resins have been increasingly used in electric and electronic parts, auto parts and mechanical parts thanks to their excellent heat resistance, mechanical properties and chemical resistance. In the field of electric and electronic parts, flame retardancy is also strongly sought for from the viewpoint of safety against fires and a composition comprising a flame retardant is used.
Although brominated polycarbonate oligomers and brominated epoxy oligomers have been studied as flame retardants for polyester resins, excellent moldability such as high fluidity and residence stability have been required of polyester resin compositions to meet demand for lightweight and small-sized electric and electronic parts as well as demand for improved productivity.
The brominated polycarbonate oligomers which have been widely used as a flame retardant for polyester resins have such problems as poor fluidity and low residence stability because it causes an ester exchange reaction with a polyester. The brominated epoxy oligomers have such a defect that their viscosity is considerably increased by residence due to a reaction between the terminal epoxy group thereof and the terminal carboxyl group of a polyester particularly when they contain antimony trioxide as a flame retarding aid though they have high fluidity.
To solve the above problems of the brominated epoxy oligomers, JP-A 58-118849 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses use of a brominated epoxy compound having an average polymerization degree of 11 or more and JP-A 62-169847 discloses use of two different brominated epoxy compounds having polymerization degrees of 20 or more and 0 to 10.
Although various attempts have been made to reduce reactivity by capping the terminal epoxy group of the brominated epoxy compound with another compound, a new step for capping the terminal is necessary, thereby losing economical efficiency.
Meanwhile, brominated polyacrylates are used as a flame retardant for polyester resins and have excellent fluidity. However, brominated polyacrylates do not show sufficient residence stability due to an ester exchange reaction with a polyester resin.
In recent years, importance has been attached to use of regenerated materials and recovered materials as part of efforts to improve productivity. JP-A 10-130481 discloses that even when a polyester resin composition which is flame retarded with a brominated polyacrylate is molded using a large amount of its regenerated material, the obtained molded product has excellent characteristic properties. However, both brominated epoxy compound-containing polyester resins and brominated acrylate-containing polyester resins have such a problem that changes in viscosity caused by the residence lead to fluctuations in molding conditions when a regenerated material is used, thereby reducing productivity.
With the technology of the prior art, use of a high molecular weight brominated epoxy compound reduces the fluidity of a resin and use of a low molecular weight brominated epoxy oligomer in combination with the above brominated epoxy compound does not improve the residence stability of a composition completely. Thus, it is difficult to achieve both fluidity and residence stability at the same time.
When a brominated epoxy compound is used to flame retard a resin, use of a polymer having a small amount of a terminal carboxyl group as a polyester resin which reacts with the epoxy group is effective to some extent but still unsatisfactory to adopt broader molding conditions.
The present invention has been made in view of the above circumstances.
SUMMARY OF THE INVENTION
That is, it is an object of the present invention to provide a flame-retardant polyester composition having excellent moldability such as fluidity and residence stability.
It is another object of the present invention to provide a method of molding the above flame-retardant polyester composition of the present invention.
It is still another object of the present invention to provide a molded product of the above flame-retardant polyester composition of the present invention.
The further objects and advantages of the present invention will become apparent from the following description.
Firstly, according to the present invention, the above objects and advantages of the present invention are attained by a flame-retardant polyester composition (may be referred to as “first composition of the present invention” hereinafter) comprising;
(A) 100 parts by weight of an aromatic polyester having a terminal carboxyl group concentration of 60 equivalents/ton or less;
(B) 5 to 50 parts by weight of flame retardants consisting of (B1) a brominated epoxy compound represented by the following formula (1):
wherein n is a number of 11 to 50,
and (B2) a brominated polyacrylate represented by the following formula (2):
wherein R is a hydrogen atom or methyl group, p is a number of 1 to 5, and m is a number of 20 to 160,
the (B1)/(B2) weight ratio being 5/95 to 95/5; and
(C) 2 to 20 parts by weight of antimony trioxide.
Secondly, according to the present invention, the above objects and advantages of the present invention are attained by a flame-retardant polyester composition (may be referred to as “second composition of the present invention” hereinafter) comprising the above components (A), (B) and (C), and
(D) 5 to 100 parts by weight of a fibrous inorganic filler.
Thirdly, according to the present invention, the above objects and advantages of the present invention are attained by a method of producing a molded product of a flame-retardant polyester composition, characterized in that the flame-retardant polyester composition is a mixture of 50 to 75 wt % of the first composition or the second composition of the present invention which is not used for molding yet and 50 to 25 wt % of the first composition or the second composition of the present invention which contains the same type of a flame retardant in the same amount as the above composition and which has already been used for molding and recovered.
In the fourth place, according to the present invention, the above objects and advantages of the present invention are attained by use of the first composition or the second composition of the present invention which has already been used for molding and recovered as a raw material to be mixed with the first composition or the second composition of the present invention which is not used for molding yet to produce a molded product.
Finally, according to the present invention, the above objects and advantages of the present invention are attained by a molded product of the first composition or the second composition of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be described in detail hereinafter.
(A) Aromatic Polyester
The aromatic polyester as the component (A) used in the present invention comprises dicarboxylic acid components and diol components. The dicarboxylic acid components include terephthalic acid, isophthalic acid and phthalic acid; phthalic acid derivatives such as methyl terephthalate and methyl isophthalate; and naphthalenedicarboxylic acid and derivatives thereof such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid. The diol components include aliphatic diols such as ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol and neopentyl glycol.
Preferred examples of the aromatic polyester (A) include polytetramethylene terephthalate, polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate and polytetramethylene-2,
Rader & Fishman & Grauer, PLLC
Rajguru U. K.
Seidleck James J.
Teijin Limited
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