Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-11-24
2001-05-01
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S080000
Reexamination Certificate
active
06225383
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates a resin composition comprising a polyamide resin. Particularly, the present invention relates to a flame-retardant polyamide resin composition.
Several methods have been proposed for imparting flame-retardancy to polyamide resin compositions. In general, such method is to mix a flame retardant into polyamides. As the flame retardant used for this purpose, there are known, for example, halogen-based flame retardants, nitrogen-based compounds and metal-containing compounds. In case of using halogen-based flame retardants, however, there is a problem for safety of halogen-containing gases generated on combustion of the compounds. On the ether hand, the metal-containing compounds are unsatisfactory in their flame-retarding effect.
Regarding the nitrogen-based compounds, Japanese Patent Application Laid-Open (KQKAI) Nos. 50-105744 and 53-31759 teach a method for improving flame retardancy of polyamides by adding thereto melamine-, cyanuric acid or other triazine-based compounds such as melamine cyanurate. The method, however, still involved the problem that in case where an inorganic filler, especially a fibrous material such as glass fiber, is blended in polyamides, the filler may behave like a candlewick to adversely affect flame retardancy of polyamides. There has also been the of generating a “plateout” phenomenon in which the flame retardant sublimes in the molding article to deposit on the mold, causing sticking in the cavity or deteriorating of visual appearance of the molded article, or “blooming”, i.e. a phenomenon in which part of the flame retardant separates out on the surface of the molded article.
Also, Japanese Patent Application Laid-Open (KOKAI) No. 53-49054 teaches a flame retardant composition in which melamine phosphate is blended. However, by mere addition of a salt of phosphoric acid and melamine, the mixing and extruding workability are rather deteriorated because of poor compatibility with polyamides to impair the visual appearance of the molded article.
Further, Japanese Patent Publication (KOKOKU) No. 61-49342 discloses a flame retardant composition prepared by blending melem or mellon (melem and mellon are calcined products of melamine to polyamide) to polyamide resin. Still further, Japanese Patent Application Laid-Open (KOHYO) No. 10-505875 (WO96/09344) discloses a flame retardant composition prepared by blending a reaction product of melem with phosphoric acid to polyamide. However, the above-mentioned flame retardant compositions are not sufficient in flame retardancy. Especially, in the flame retardant composition of Japanese Patent Application Laid-Open (KOHYO) No. 10-505875, the water absorbance property of the composition becomes high and the dispersibility to the polyamide becomes insufficient because of high water solubility due to the phosphate. As a result, the strength and elasticity thereof may be reduced. Further, the hot bend strength (temperature dependency of bending modulus) thereof may be reduced. Also, when the flame retardant compositions absorb water, reaction product of melem-phosphate is easily transferred to the surface of a molding product thereof, thereby deteriorating the surface appearance.
As a result of the present inventors' earnest studies to solve the above problems, it has been found that by blending (i) a salt of polyphosphoric acid and melam or a melam derivative, (ii) a salt of polyphosphoric acid and melem or a melem derivative, or (iii) mixture thereof with a polyamide resin, a polyamide resin composition has excellent thermal and mechanical properties as well as flame retardancy, and is also capable of providing the molded articles with excellent visual appearance. The present invention has been attained on the basis of the above finding.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a polyamide resin composition having excellent thermal and mechanical properties and flame retardancy in addition to the excellent inherent properties of polyamides and also capable of providing the molded articles with excellent visual appearance.
To accomplish the aims mentioned above, in a first aspect of the present invention, there is provided a resin composition comprising:
100 parts by weight of resin component comprising a polyamide resin or a polyamide resin and a thermoplastic resin other than the polyamide resin, and
1 to 50 parts by weight of (i) a salt of polyphosphoric acid and melam or a melam derivative, (ii) a salt of polyphosphoric acid and melem or a melem derivative or (iii) a mixture thereof.
In a second aspect of the present invention, there is provided a resin composition comprising:
100 parts by weight of resin component comprising a polyamide resin or a polyamide resin and a thermoplastic resin other than the polyamide resin,
1 to 50 parts by weight of a salt of polyphosphoric acid and melam or a melam derivative, a salt of polyphosphoric acid and melem or a melem derivative or mixture thereof, and
0.1 to 20 parts by weight of a phosphoric flame retardant other than the salt of polyphosphoric acid and melam or a melam derivative, a salt of polyphosphoric acid and melem or a melem derivative or mixture thereof, and
0.1 to 300 parts by weight of an inorganic filler.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in more detail as follows.
The resin component in the composition of the present invention comprises a polyamide resin alone or a polyamide resin and a thermoplastic resin other than polyamide resins. Examples of the polyamide resins usable in the present invention include, though not limited to, nylon 6, nylon 66, nylon 69, nylon 610, nylon 612, nylon 12, polyamide resins obtained from xylenediamine and x,o-linear aliphatic dibasic acids (these polyamide resins may hereinafter be referred to as MX nylon) and their mixtures. It is preferred to use MX nylon, or the mixtures of MX nylon, nylon 66 and/or nylon 6. The mixed resins comprising MX nylon and nylon 66 are more preferred.
In case where the mixed polyamide resin used is a resin comprising MX nylon, nylon 66 and/or nylon 6, the weight ratio of nylon 66 and/or nylon 6 to MX nylon is 0.1-100:100, preferably 0.1-80:100.
The thermoplastic resins other than the polyamide resins usable in the present invention include polystyrene resins, ABS resins, AES resins, AS resins, olefin resins, methacrylic resins, polycarbonate resins, polyacetal resins, polyphenylene ether resins (PPE resins), modified PPE resins, polyester resins, polysulfone resins, polyimide resins, polyphenylene sulfide resins, polyarylate resins, polyether sulfone resins, polyether ketone resins, polyether ether ketone resins, polyester carbonate resins, amorphous polyamide resins, liquid crystal polymers, and alloy resin compositions comprising two or more of these resins. Of these resins, polyphenylene ether resins (PPE resins) are preferred. If necessary, inorganic or organic fibrous filler, other types of filler, stabilizer, ultraviolet absorber, dye, pigment and other additives may be added to the composition.
In case where the resin component in the composition of the present invention comprises a polyamide resin and other thermoplastic resin, the weight ratio of the polyamide resin to the other thermoplastic resin preferably is 99/1 to 1/99, more preferably 90/10 to 10/90, even more preferably from 70/30 to 30/70.
The polyphenylene ether resins usable in the present invention are the polymers having the structural unit of the following formula (1) in the main chain, and they may be homopolymers, copolymers or graft polymers:
wherein R
1
is a lower alkyl group having 1 to 3 carbon atoms; R
2
and R
3
are each a hydrogen atom or a lower alkyl group having 1 to 3 carbon atoms; and n is a repeating number.
Typical examples of such polyphenylene ether resins are poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, and poly(2-methyl-6-propyl-1,4-phenylene) ethe
Hirono Masaki
Watanabe Noriyoshi
Hoke Veronica P.
Mitsubishi Engineering Plastic Corp.
Parkhurst & Wendel L.L.P
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