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
1999-04-14
2001-09-04
Michl, Paul R. (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...
C524S424000, C524S427000, C524S432000
Reexamination Certificate
active
06284828
ABSTRACT:
DESCRIPTION
BACKGROUND OF THE INVENTION
1. Field of Industrial Application
The present invention relates to a polyacetal resin composition excellent in friction and abrasion resistance properties by improving the compatibility, dispersibility and interfacial adhesion between resins, which is obtained by blending a polyacetal resin with a specific olefinic polymer, an alkylene oxide polymer having a primary or secondary amine group(s), an inorganic filler together with, further, a lubricant if required, and melting and kneading.
2. Prior Arts
Since polyacetal resins have a well-balanced mechanical properties and are excellent in, for example, friction resistance and abrasion resistance properties, chemical resistance, heat resistance and electric characteristics, they have been widely used in some fields such as automobiles and electrical and electronic appliances. However, the performances required in such fields are gradually escalating. As one example, there has been desired to further improve the sliding performances as well as general physical properties. Such sliding performances include the friction and abrasion resistance properties against inorganic filler-blended materials.
For example, high requirements for decreasing costs and weights increases such cases that inorganic filler-blended materials, which is obtained by blending inorganic fillers such as glass fibers, glass flakes, talc and mica with a resin such as ABS, PC/ABS and PBT/ABS, are used for chassis of CD-ROM or the like. Generally, gear parts and lever parts are slid against the metal boss caulked or formed in a sheet metal chassis so that the friction and abrasion resistance properties against metal materials have been important. However, since the boss and others are molded together with the chassis into one piece using such resin materials, the sliding performances against the resin-made boss or resin-made guide has become more important.
The sliding against materials for the resin-made chassis needs much better friction and abrasion resistance properties than those necessary for the conventional sliding against metal materials because of insufficient friction and abrasion resistance properties inherent to ABS resin, as a partner material, and the effects of surface roughness caused by blended inorganic fillers. Thus, the improvement of such properties has been required.
In general, addition of a fluororesin or a polyolefinic resin, or addition of a lubricant such as fatty acids, fatty acid esters, silicone oils or various mineral oils, to polyacetal resins is effected for the purpose of the improvement of the sliding performances.
The addition of a fluororesin or a polyolefinic resin improves the sliding performances to a certain extent. However, since these resins other than the polyacetal resins exhibit poor compatibility with the polyacetal resins, the resultant resin compositions have unsatisfactory sliding performances under a high surface pressure, and they have poor abrasion resistance properties in the sliding against inorganic filler-blended materials. Further, there are problems in that they are liable to cause peeling on the surfaces of molded articles or to form a deposition on a mold.
While, the addition of a lubricant has various disadvantages such as the trouble of the processing in extrusion or molding, or the bleeding during using. Moreover, when used together with the above-mentioned resins other than the polyacetal resins, the lubricant inhibits the compatibility between these resins and the polyacetal resins and greatly deteriorates the abrasion resistance properties. For such problems, materials with these properties improved have been desired.
DISCLOSURE OF THE INVENTION
The present inventor has extensively investigated to attain the above object, and as a result, he has found that a resin composition having excellent sliding performances can be obtained by blending a polyacetal resin with a specific polyolefinic polymer, an alkylene glycol polymer and an inorganic filler optionally together with, further, a particular lubricant, and melting and kneading them, thus completed the present invention.
That is, the present invention provides a polyacetal resin composition prepared by blending
(A) 100 parts by weight of a polyacetal resin,
(B) 0.5 to 100 parts by weight of a modified olefinic polymer obtained by modifying an olefinic polymer (B-1) with at least one selected from the group consisting of an unsaturated carboxylic acid and acid anhydride thereof and derivatives thereof (B-2),
(C) 0.01 to 10 parts by weight of an alkylene glycol polymer having a primary or secondary amine group(s) with a number average molecular weight of 400 to 500,000, and
(D) 0.1 to 20 parts by weight of an inorganic filler, and melting and kneading them.
In other words, the present invention provides a composition comprising the above-described components, (A), (B), (C) and (D).
DETAILED DESCRIPTION OF THE INVENTION
Components of the present invention will be described below.
The polyacetal resin (A) used in the present invention is a polymer having, as the main constitution, an oxymethylene group (—CH
2
O—). It may be any of a polyoxymethylene homopolymer or a copolymer, terpolymer or block polymer having, as the main repeating unit, an oxymethylene group and containing, other than such a unit, a small quantity of other unit(s), for example, a unit derived from a comonomer such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol; or may be not only a linear one but also one having a branched or cross-linked structure in the molecule; or may be a known modified polyoxymethylene having other organic group(s) introduced. Also, the polymerization degree is not particularly limited, and it may be one having a melt-moldability. Preferable polyacetal resin is one having a melt index (measured according to ASTM D-1238-89E, hereinafter abbreviated as MI) of 1 to 50 g/10 min., still more preferably one having a MI of 7 to 30 g/10 min.
Next, component (B) blended with the polyacetal resin in the present invention is a modified olefinic polymer obtained by modifying an olefinic polymer (B-1) with at least one member selected from the group consisting of an unsaturated carboxylic acid, and an acid anhydride and derivatives thereof (B-2). The olefinic polymer (B-1) to be used herein includes a homopolymer of an &agr;-olefin such as ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and 1-dodecene; a copolymer consisting of two or more of these a-olefins; and a random-, block- or graft-copolymer containing these a-olefins and at least one of the comonomer components selected from among &agr;,&bgr;-unsaturated acids such as acrylic acid and methacrylic acid, &agr;,&bgr;-unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and hydroxyethyl methacrylate, non-conjugated dienes such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 2,5-norbornadiene, conjugated dienes such as butadiene, isoprene and piperylene, aromatic vinyl compounds such as &agr;-methylstyrene, vinyl ethers such as vinylmethyl ether and derivatives of these vinyl compounds. The polymerization degree, the presence or absence, or the degree of side chains or branches, the composition ratio of the copolymer and the like have no limitation.
More concrete examples of the olefinic polymer (B-1) in the present invention include polyethylene produced by high-pressure method, polyethylene produced by low or medium pressure method, ethylene-&agr;-olefin copolymers produced by gas-phase method, LLDPE, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer and ethylene-propylene-diene terpolymer. Preferable are polyethylene, polypro
Michl Paul R.
Nixon & Vanderhye P.C.
Polyplastics Co. Ltd.
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