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
2001-03-06
2002-04-16
Yoon, Tae H. (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...
C524S127000, C524S147000, C523S200000
Reexamination Certificate
active
06372835
ABSTRACT:
TECHNICAL FIELD
The present invention relates to flame-retarding of a polyketone resin useful as electrical and electronic components of office automation equipment and household appliances and housing components thereof, automobile parts and machine parts. More specifically, it relates to a flame-retarded polyketone resin composition obtained by mixing specific magnesium hydroxide particles into a polyketone resin and to molded articles thereof.
BACKGROUND ART
A polyketone resin is a novel resin which has been successfully synthesized from carbon monoxide and an olefin to be developed in recent years, and mechanical properties thereof fall into the category of engineering plastics. U.S. Pat. Nos. 4,843,144 and 4,880,903 disclose the production method of a linear alternating ketone terpolymer which is synthesized from an olefin such as ethylene and propylene and carbon monoxide. The thus-obtained polyketone resin is excellent in impact resistance, exhibits high impact resilience both at room temperature and at low temperatures and has excellent creep properties. However, it also has such problems that it is susceptible to a crosslinking reaction during such processes as extrusion and injection, that it has poor melt-stability and that it discolors during processing. To solve these problems, it is disclosed in Japanese Patent Laid-Open Publication No. 11-116795 that an increase in stability at the time of melt-processing and a reduction in discoloration can be accomplished by adding a stabilizer comprising a polyol and an aluminum hydroxide compound to an aliphatic ketone polymer synthesized from carbon monoxide and at least one ethylenic unsaturated hydrocarbon. In addition, the addition of an impact resistance improving agent, a flame retardant, a reinforcing filler, an antioxidant and other polymer is also disclosed therein. However, there is no detailed description of flame-retarding of this polymer in the publications.
Further, Japanese Patent Laid-Open Publication No. 11-71513 discloses a polyketone resin composition obtained by mixing 0.01 to 50 parts by weight of a liquid crystal resin, for the purpose of improving the thin-wall flowability, heat resistance, resistance to organic solvents and moldability which are useful as housing components, and 0.01 to 60 parts by weight of a flame retardant into 100 parts by weight of a polyketone resin. This publication discloses that an organic bromide, an organic phosphide, a red phosphor and the like can be used as the flame retardant and that the red phosphor may be coated with a metal hydroxide such as magnesium hydroxide. However, from the point of safety orientation at the present time, the use of the organic halogen-containing flame retardant is on its way to diminish, and the flame retardant containing phosphorus such as red phosphor is not considered satisfactory because of such problems as the generation of phosphine gas, odor and discoloration at the time of processing.
Problems to be Solved by the Invention
The object of the present invention is to provide a flame-retardant polyketone resin composition which does not cause damage to the working environment during the flame retarding process of a polyketone resin composition, has good moldability, retains the physical properties of the resin, and is useful as electrical and electronic components of office automation equipment and household appliances and housing components thereof, automobile parts and machine parts, all of which have an excellent appearance.
Means for Solving the Problems
The present inventors have made various studies to solve the above problems and completed the present invention by mixing a predetermined amount of specific magnesium hydroxide particles into a polyketone resin.
The magnesium hydroxide particles used in the present invention are coated surface of magnesium hydroxide particles whose crystals grow well and which hardly agglomerate. The production method of the magnesium hydroxide particles as an additive or a flame retardant for a resin has already been known, and the magnesium hydroxide particles whose crystals grow well and which hardly agglomerate can exhibit good moldability, mechanical strength and flame retardancy. They are synthesized by the reaction between an aqueous magnesium salt such as magnesium chloride and an alkali such as caustic soda. Further, magnesium hydroxide particles obtained by the re-hydration of magnesium oxide or natural magnesium hydroxide can also be used as the flame retardant.
However, when the conventional magnesium hydroxide particles or magnesium hydroxide particles whose crystals have been fully grown for the purpose of improving the dispersibility in a resin are mixed into a polyketone, the polyketone is degraded by the heat generated at the time of molding. Since this degradation affects the mechanical properties and coloration, surface-treated magnesium hydroxide particles are used in the present invention.
According to the studies made by the present inventors, the above object of the present invention is achieved by a flame-retardant polyketone resin composition which substantially comprises (1) 40 to 85% by weight of a polyketone resin based on the total weight of the composition and (2) 15 to 60% by weight of magnesium hydroxide particles, based on the total weight of the composition, which have (a) a specific surface area measured by a BET method of 1 to 15 m
2
/g, (b) an average secondary particle diameter of 0.2 to 5 &mgr;m, and (c) a surface coated with a surface-treating agent.
The resin composition of the present invention will be described in more detail hereinafter.
The polyketone resin used in the present invention is generally referred to as an aliphatic polyketone resin. The polyketone resin is obtained by reacting an olefin which mainly contains ethylene with carbon monoxide as described above. The polyketone resin may be one that can be used for molding and can be produced by any methods.
The polyketone resin is preferably a resin obtained by reacting an olefin mixture containing ethylene and a small portion of other olefin with carbon monoxide. The particularly preferable polyketone resin is a linear alternating ketone terpolymer in which the molar ratio (Y/X) of the following recurring units (X) and (Y) in the main chain:
—CO(CH
2
—CH
2
)—
(X)
—CO(D)—
(Y)
(wherein D is an alkylene chain other than the ethylene chain (—CH
2
—CH
2
—)) is 0.01 to 0.2, preferably 0.02 to 0.1. The above recurring unit (X) is a unit based on ethylene, and the above recurring unit (Y) is a unit based on an olefin other than ethylene. The D in this Y is specifically an alkylene chain based on propylene, butylene, pentene or styrene, and the alkylene chain based on propylene is particularly preferable.
In the present invention, the magnesium hydroxide particles mixed into the above polyketone resin has a specific surface area measured by a BET method of 1 to 15 m
2
/g, preferably 2 to 10 m
2
/g. Further, the magnesium hydroxide particles have an average secondary particle diameter measured by a laser beam diffraction-scattering method of 0.2 to 5 &mgr;m, preferably 0.5 to 3 &mgr;m.
When the magnesium hydroxide particles having the above form are mixed into the polyketone resin in such an amount that is sufficient to impart flame retardancy to the polyketone resin, the flowability substantially lowers, the moldability deteriorates and the physical properties lower.
In the present invention, the magnesium hydroxide particles having the above form are coated with a surface-treating agent before use. When the surface-coated magnesium hydroxide particles are used, the resin composition exhibits improved flowability and excellent moldability, and the obtained molded article exhibit improved physical strength and coloring properties. As a matter of course, flame retardancy of at least V-1 is achieved on the basis of the UL94 standard, and flame retardancy of V-0 is achieved in most cases.
Illustrative examples of the surface-treating agent used for coating the surfaces of the magnesium hydroxide particles inclu
Nosu Tsutomu
Sawa Yoshiharu
Kyowa Chemical Industry Co. Ltd.
Yoon Tae H.
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