Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/02—Parts of sliding-contact bearings
  • F16C33/04—Brasses; Bushes; Linings
  • F16C33/20—Sliding surface consisting mainly of plastics
  • F16C33/201—Composition of the plastic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L59/00—Compositions of polyacetals; Compositions of derivatives of polyacetals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L55/00—Compositions of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08L23/00 - C08L53/00
  • C08L55/02—ABS [Acrylonitrile-Butadiene-Styrene] polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds

Definitions

• the present invention relates to a polyacetal resin composition, the principle component of which is a polyacetal resin, and to a resin composition that has excellent friction-wear characteristics suitable for use in sliding parts. It further specifically relates to a polyacetal resin composition that provides good friction-wear resistance when used as a sliding part against a counter sliding part regardless of its material of construction.
• Polyacetal resins which are thermoplastic, exhibit excellent mechanical properties and heat resistance, particularly good friction-wear resistance characteristics and are, thus, used in sliding parts applications in a broad range of fields.
• inorganic solid lubricants such as molybdenum disulfide and graphite, petroleum-type lubricants, synthetic lubricants, aliphatic alcohol or its ester-type liquid or semi-liquid lubricants, or a polyolefin resin fine powder having a molecular weight of at least 500,000.
• the present invention relates to a polyacetal resin composition
• a polyacetal resin composition comprising not more than 15% by weight of a polyolefin resin, preferably at least 0.5% by weight up to 15% by weight, that has a density of not more than 0.93 g/cm 3 and a weight average molecular weight of less than 500,000.
• polyacetal resin is meant not only a polyacetal homopolymer, but also a polyacetal copolymer with a cyclic either or a cyclic polymer. It is, however, preferred to use a polyacetal homopolymer because the addition of a lubricant to a copolymer sometimes will reduce its physical properties (tensile characteristics, Izod impact characteristics, flexural characteristics, compression properties, and the like).
• polyolefin resin refers to aliphatic-alpha-olefin homopolymers, such as polyethylene, polypropylene, and polymethyl pentene, or copolymers of aliphatic-alpha-olefins themselves. Such copolymers may contain a small amount of a diene-type hydrocarbon comonomer.
• the polyolefin resin used in this invention must have a density of not higher than 0.93 g/cm 3 and a weight average molecular weight of not higher than 500,000. Polyolefins having such densities and molecular weights disperse in the polyacetal in fine particles of not more than 10 microns in size.
• Preferred polyolefin resins which are commercially readily available are polyethylene and polypropylene, most preferably polyethylene.
• the polyacetal resin composition of this invention is obtained by mixing at least 85% by weight of a polyacetal resin and up to 15%, inclusive, by weight of a polyolefin resin in a conventional mixer.
• the polyolefin resin should be used normally in an amount of at least 0.5% by weight, preferably in a range of 0.5-10% by weight. The use of more than 15% by weight will reduce the excellent physical properties inherent in the polyacetal resin and also will deteriorate its processability.
• the polyacetal resin composition of this invention can be used with no differences in the areas in which the polyacetal resins have been previously used. Use of this composition with a sliding part material is particularly preferred because it exhibits high frictional wear resistance, regardless of the material of the counter sliding part material that it comes in contact therewith.
• the polyacetal resin composition of this invention may be further compounded with various additives that are used in polyacetal resins, such as a stabilizer, a nucleating agent, an antistatic agent, a flame retardant, a colorant, a lubricant, or the like, as well as with fibrous or granular fillers or reinforcing agents.
• additives such as a stabilizer, a nucleating agent, an antistatic agent, a flame retardant, a colorant, a lubricant, or the like, as well as with fibrous or granular fillers or reinforcing agents.
• HDPE High-density polyethylene, HD 6733.19 (a product of the Exxon Company)
• EVA Ethylene-vinyl acetate copolymer
• ELVAX 40 a * • ⁇ • ⁇ ⁇ product of E. I. du Pont de Nemours and Company
• PE-g-As Polyethylene-styrene/acrylonitrile grafted copolymer, Modiper 1400 (a product of Nippon Yushi)
• Test 1 Density: 0.97 g/cm 3
• the specimens of Test 1 each contained 2.0% of a resin additive comprising a polyolefin and other resin.
• ABS ABS Resin
• Cycolac 5500 a product of the GE
• PET 20% glass fiber reinforced polyethylene terephthalate, Rynite ® 530 (a product of E. I. du Pont de Nemours and Company).
• a polyacetal resin composition sheet (Sample 1) is placed on a tabletop capable of making a horizontal reciprocal movement with an amplitude of 2.75 inches; on the polyacetal resin sheet top surface is placed a 1/4 inch wide by 1 inch long sliding counter material-made from a resin sheet (Sample 2), fixed so as not to make any horizontal movement, and a 40 psi load is applied to Sample 2.
• the tabletop was allowed to make a typical reciprocal movement at an average rate of 30 feet/min for 3 hours.
• the weight loss of each resin sheet before and after the above test was measured and wear characteristics was calculated by the following equation: Equation 1
• V rate (ft/min)
• Test Nos. 1-4 are Examples of this invention and Test Nos. 5-6 are Comparative
• the polyacetal resin composition of this invention constantly gives excellent friction-wear resistance characteristics regardless of the sliding conditions, such as load and speed, or regardless of the material of the counter surface.
• the polyacetal resin composition of this invention can exhibit excellent sliding characteristics of friction-wear resistance with low coefficients of friction regardless of the sliding part counter part material even when the sliding surfaces have elevated temperatures, generated by the heat of friction.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (2)

Applications Claiming Priority (4)

Publications (1)

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Cited By (3)

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• 1994
  • 1994-06-15 CA CA002164934A patent/CA2164934A1/en not_active Abandoned
  • 1994-06-15 WO PCT/US1994/006760 patent/WO1995000585A2/en not_active Application Discontinuation
  • 1994-06-15 KR KR1019950705682A patent/KR960703154A/ko not_active Application Discontinuation
  • 1994-06-15 EP EP94921961A patent/EP0703947A4/en not_active Withdrawn

Non-Patent Citations (1)

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