JPH0476048A - Sliding part - Google Patents

Abstract

PURPOSE:To mold a sliding part having excellent friction and wearing characteristics and making a low frictional sound during sliding by compounding a specific graft copolymer, a polybutylene terephthalate and/or a polyethylene terephthalate, and an inorg. filler. CONSTITUTION:A resin compsn. comprising 25-90wt. % graft copolymer obtd. by grafting 30-90 pts.wt. monomer mixture consisting of 40-80wt.% arom. vinyl monomer, 20-40 wt.% vinyl cyanide monomer, and 0-40 wt.% other copolymerizable vinyl monomer onto 10-70 pts.wt. rubberlike polymer, 10-75 wt.% polybutylene terephthalate and/or polyethylene terephthalate, and 0-45 wt.% inorg. filler is molded into a sliding part.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a sliding part made of a specific resin composition, and more specifically, it has excellent dimensional stability, thin-wall strength, impact resistance, and chemical resistance. 6. Concerning molded sliding parts that have extremely excellent friction and wear characteristics, especially long-term sustainability and low friction noise caused by sliding (Conventional technology and its problems) In recent years, Electronic equipment such as audio/visual (AV) equipment and printers
In the field of electrical equipment, sliding parts for office equipment, and mechanical parts,
Plastics are being used in place of metals primarily to significantly reduce costs, including assembly and processing costs, and to reduce weight. Currently, polybutylene terephthalate (PB
T) and polyethylene terephthalate (hereinafter referred to as PET)
Thermoplastic polyester resins and polyacetal (hereinafter referred to as POM) resins are widely used for sliding parts and mechanical parts because of their excellent physical and chemical properties such as mechanical strength as well as friction and wear properties. However, in such fields, it is often necessary to further improve the properties of the abrasive, especially in order to reduce assembly processing costs by making sliding parts greaseless and to improve the quality of molded products.
Further improvement in frictional wear characteristics and long-term sustainability, as well as reduction in frictional noise caused by sliding, and low frictional noise are required.

The thermoplastic polyester resin conventionally used for sliding parts has insufficient friction and wear characteristics under high-speed, high-load sliding conditions, and also has poor friction and wear characteristics even under low-speed, low-load conditions after long-term use. There was a problem in that the wear characteristics were significantly reduced, resulting in a lack of long-term stability and reliability as a sliding component. Furthermore, polyacetal resins have problems in that they produce a large amount of frictional noise when sliding between similar materials, and that their frictional and wear characteristics are insufficient for long-term use.

For this reason, in any case, it is necessary to perform treatments such as applying grease to long-term sliding parts, which is a major factor in increasing assembly costs.

(Another Means to Solve the Problems) That is, the present invention provides the following: (A) 10 to 70 parts by weight of a rubbery polymer, 40 to 80% by weight of an aromatic vinyl monomer, and 20 to 20 to 20 to 200% of a vinyl cyanide '4'-m compound. 40% by weight, and a monomer mixture 30 to 90% consisting of 0 to 40% by weight of a vinyl monomer copolymerizable with these.
(B) 10-75% by weight of polybutylene terephthalate and/or polyethylene terephthalate (C) Molded with a resin composition consisting of 0-45% by weight of an inorganic filler This is a sliding part characterized by:

The rubbery polymer constituting the graft copolymer used in the present invention is a butadiene polymer, a copolymer of butadiene and a copolymerizable vinyl monomer, an ethylene-propylene copolymer, and a copolymer of butadiene and an aromatic copolymer. block copolymer,
Examples include copolymers of acrylic esters and vinyl monomers copolymerizable with the acrylic esters. As the aromatic vinyl It polymer constituting the graft copolymer used in the present invention, styrene and α-methylstyrene 'l'-fi is particularly preferable.

Examples of vinyl cyanide monomers include acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile, with acrylonitrile being particularly preferred. Examples of vinyl monomers that can be copolymerized with these include methacrylic acid esters such as methyl methacrylic ester and ethyl methacrylic ester, and vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid.

The method for producing the graft copolymer consists of adding 10 to 70 polymers of a rubbery polymer, 40 to 80% by weight of an aromatic vinyl monomer, 20 to 40% by weight of a vinyl cyanide monomer, and, if necessary, these components. Vinyl jli fi1 body O~4 copolymerizable with
It is obtained by polymerizing 30 to 90 parts by weight of a monomer mixture containing 0% by weight. In producing this Graph I copolymer, any generally known polymerization technique can be employed, such as suspension polymerization, aqueous heterogeneous polymerization such as emulsion polymerization,
Bulk polymerization, solution polymerization, precipitation polymerization of the resulting polymer in a non-solvent, etc. or a combination thereof can be used.

Polyethylene terephthalate (PET) used in the present invention
) is mainly composed of terephthalic acid (or its ester-forming derivative) and ethylene glycol (or its ester-forming derivative), and polybutylene ethylene terephthalate-1- (PBT) is composed of terephthalic acid (or its ester-forming derivative). It is a polymer obtained by a condensation reaction mainly consisting of tetramethylene glycol (or its ester-forming derivative) and tetramethylene glycol (or its ester-forming derivative). Acid components include isophthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, and their ester-forming derivatives; diol components include ethylene glycol, propylene glycol,
It may be substituted with tetramethylene glycol or an ester-forming derivative thereof in an amount of 20 mol % or more.

The composition of the resin used in the molded article of the present invention is 7% by weight of the graft copolymer (A) and 7% by weight of polybutylene terephthalate and/or polyethylene terephthalate (B). If the content of the graft copolymer is 90% by weight or more, the physical properties such as heat resistance and mechanical strength of the molded product will deteriorate. Further, the wear characteristics are also deteriorated, and the amount of wear on itself becomes large, which is not preferable. Furthermore, if the graft copolymer content is less than 25% by weight, sufficient long-term stable frictional wear characteristics and low friction noise cannot be obtained. Furthermore, since the molding shrinkage of the molded product becomes large, reinforcing the molded product with glass fibers increases the anisotropy of the molding shrinkage and tends to cause warping, which is undesirable as it also reduces dimensional stability.

Considering the balance of various physical properties, it is more preferable that (
The content of the graft copolymer (A) is 30 to 70% by weight, and the content of the polyester (B) is 70 to 30% by weight.

Inorganic fillers used in the present invention include glass fiber, glass flakes, glass beads, talc, quartz, mica,
Examples include calcium silicate and titanium dioxide, but particularly preferred are glass fiber, glass flakes, and glass peas. If the amount added exceeds 0 to 45% by weight of the composition, fluidity during molding will decrease, and moldability and surface condition will deteriorate. Moreover, the coefficient of friction becomes large and the sliding characteristics deteriorate, which is not preferable.

The resin composition for molding the sliding part of the present invention may contain a nucleating agent, a flame retardant, a mold release agent, an antioxidant, a lubricant, an antistatic agent, a coloring agent, and the like.

Further, in the molded sliding part of the present invention, an auxiliary thermoplastic resin may be used in combination to improve other physical properties within a range that does not impede the purpose.

Specific examples of the sliding parts of the present invention include radio cassette players,
Mechanical chassis, buttons, levers, gears, bearings,
Carriages, etc.

(Example) The present invention will be explained below with reference to Examples.

The sliding properties were determined using a Suzuki friction and wear tester, using a pressing force of 2 kg/cJ, a speed of 10 cm/see, a contact area of 2 ci, and a mating material of polyacetal resin, with a friction coefficient of 1 and a contact surface of 1 The friction coefficient and specific wear amount when sliding for 1 km were measured. In addition, as a fricative sound characteristic, the occurrence of squeak noise during sliding was evaluated in the same test as above. Fricative sound characteristics were evaluated between similar materials.

The tensile strength was measured using a test method based on ASTM D-038.

Examples 1 to 4, Comparative Examples 1 to 3 Graft copolymer (52.5% by weight of styrene, 17.5% by weight of acrylonitrile, 30% by weight of polybutadiene)
, PBT resin, and glass fibers (denoted as G and F) were mixed in the weight proportions shown in Table 1, and the mixture was kneaded and extruded using a 40φ extruder to form pellets. Using this pellet, an outer diameter of 25.6 mm, an inner diameter of 20.0 mm, and
A cylindrical molded piece with a height of 15+++ m and a standard test piece for measuring each physical property were prepared, and the sliding characteristics and other physical properties were evaluated. As comparative examples, PBT resin and polyacetal resin were also evaluated in the same manner. The results are shown in Table 1.

As is clear from Table 1, the molded product of the present invention has extremely excellent long-term stability in friction and wear characteristics, and does not generate any squeaks during sliding.

(Effects of the Invention) As is clear from the above description and examples, the molded product of the present invention has excellent long-term friction and wear characteristics, frictional noise during sliding, and other sliding properties. It is used as a sliding part with no problems in other mechanical strength, physical, or chemical properties.

Applications of the molded sliding parts of the present invention include electrical/electronic equipment, office equipment, etc., but typical examples include radio cassette players, video tape recorders, video cameras, video disc players, compact disc players, printers, copying machines, and facsimiles. , word processors, etc., and is suitably used for mechanical chassis, buttons, lever gears, bearings, carriages, etc. of these devices.

Patent applicant: Daicel Chemical Industries, Ltd. (1)

Claims (1)

[Claims] 1) (A) 10 to 70 parts by weight of rubbery polymer, 40 to 80 parts by weight of aromatic vinyl monomer, and 20 parts by weight of vinyl cyanide monomer.
~40% by weight, and 25 to 90% by weight of a graft copolymer grafted with 30 to 90 parts by weight of a weight mixture consisting of 0 to 40% by weight of a vinyl monomer copolymerizable with these (B) Polybutylene terephthalate and/or 10 to 75% by weight of polyethylene terephthalate (C) 0 to 45% by weight of an inorganic filler.