Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-02-12
2000-04-18
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525398, 524405, 524413, 524593, C08L 5900, C08K 534, C08C 1922
Patent
active
060516607
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a polyacetal resin molded article in which an amino-substituted triazine compound is dispersed in the form of particles having an average particle size of not more than 1 .mu.m in a polyacetal resin and to a process for producing the same.
BACKGROUND ART
Polyacetal resins are excellent in balance of mechanical properties, chemical resistance and coefficient of friction, and therefore, have been used as typical engineering plastics over a wide range including electric and electronic parts, automobile parts and other mechanical parts. When so used, thermal aging resistance and surface appearance of molded article are important characteristics.
Polyacetal resin compositions prepared by adding an amino-substituted triazine compound to a polyacetal resin are already known. For example, Japanese Patent Application Kokai No. 60-90,250, Japanese Patent Application Kokai No. 7-173,368 and Japanese Patent Application No. 7-331,028 disclose polyacetal resin compositions for the purpose of improving the thermal stability. Also, Japanese Patent Application Kokai No. 2-80,416 discloses a method of the addition of the above compound to a crude polyacetal resin before the terminal stabilization for the purpose of enhancing the compatibility with the polyacetal resin.
However, in these methods, the amino-substituted triazine compound is poor in compatibility with a polyacetal resin, and hence, cannot be dispersed in the form of particles having an average particle size of not more than 1 .mu.m in the polyacetal resin. In addition, when the molded article is allowed to stand for several days, the compound bleeds to the surface of the molded article resulting in bad surface appearance. On the other hand, Japanese Patent Application Kokai No. 2-80,416 discloses a method of improving the non-bleeding properties of an amino-substituted triazine compound. However, by this method, it is impossible to obtain a polyacetal resin molded article in which the amino-substituted triazine compound is dispersed in the form of particles having an average particle size of not more than 1 .mu.m in the polyacetal resin. This is because the time of melt-mixing the polyacetal resin with melamine is long and hence formaldehyde reacts with the melamine and the reaction products further react with each other and aggregate, whereby the particle sizes of dispersed particles become larger.
DISCLOSURE OF THE INVENTION
The present inventors have made extensive research on the above problems and consequently found that a polyacetal resin molded article excellent in thermal aging resistance, surface appearance and dimensional precision can be obtained by dispersing an amino-substituted triazine compound in the form of particles having a specific average particle size in a polyacetal resin.
An object of this invention is to provide a polyacetal resin molded article in which an amino-substituted triazine compound is dispersed in the form of particles having an average particle size of not more than 1 .mu.m in the polyacetal resin.
A further object of this invention is to provide a process for producing the above polyacetal resin molded article.
A still further object of this invention is to provide a polyacetal resin molded article excellent in thermal aging resistance and surface appearance and having non-bleeding properties.
Other objects and advantages of this invention will become apparent from the following description.
According to this invention, there is provided a polyacetal resin molded article in which an amino-substituted triazine compound is dispersed in the form of particles having an average particle size of not more than 1 .mu.m in the polyacetal resin.
According to this invention, there is also provided a process for producing a polyacetal resin molded article which comprises melt-mixing 100 parts by weight of a polyacetal resin having a formaldehyde content of 1,000 to 3,000 ppm with 0.01 to 3.0 parts by weight of at least one amino-substituted triazine compound and subjecting the mixture to
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Asahikasei Kogyo Kabushiki Kaisha
Wu David W.
Zalukaeva Tanya
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