JP5137287B2 - Polyacetal resin composition and sliding part - Google Patents

Description

  The present invention relates to a polyacetal resin composition and a sliding component that are excellent in slidability and can achieve a higher limit PV value without impairing the inherent mechanical properties of the polyacetal resin.

  Polyacetal resins have balanced mechanical properties and are excellent in heat resistance, chemical resistance, and electrical characteristics, and thus are widely used in the automotive field and electrical / electronic field. In recent years, the required characteristics have gradually become more advanced in such fields. For example, in the use as mechanical parts and parts for electrical and electronic equipment, excellent sliding properties as well as mechanical properties, improvement of limit PV value, sliding friction sound ( Reduction of squeak noise is required.

  Among these required characteristics, various attempts have been made in the past to further improve the slidability and reduce the sliding friction noise (squeak noise).

  For example, Patent Document 1 discloses a method for obtaining excellent slidability without blending a lubricant by blending a polyacetal resin with a graft polymer of ultra-low density polyethylene and a vinyl-based polymer. In addition, a graft copolymer in which one or more of an olefin polymer and a vinyl polymer or an ether polymer are chemically bonded in a branched or cross-linked structure, and a lubricant and an inorganic compound are blended with the polyacetal resin. Thus, it is disclosed that generation of squeak noise during sliding can be reduced in addition to improvement of friction and wear characteristics. Patent Document 3 discloses that the friction and wear characteristics at a particularly high temperature can be improved by blending a polyolefin resin having an ethylene content of 30 to 100% by weight produced using a single site catalyst with a polyacetal resin. Has been.

  On the other hand, Patent Document 4 shows excellent friction and wear properties, molding processability, and low noise characteristics by blending a polyacetal resin with a copolymer of ethylene and α-olefin or a modified polyethylene wax thereof. It is disclosed.

However, in any of these known methods, the slidability is improved to some extent, but it is not sufficient from the viewpoint of the limit PV value of the material, and in an environment where high load and high speed are used, Similarly, it has been addressed by applying grease or using a material containing a fluorine-based lubricant. However, the application of grease has problems such as deterioration of the surrounding environment and high cost, and the material cost of materials containing fluorine-based lubricants is significantly high, so it is low in high load and high speed environments. Therefore, a material that can achieve grease-less has been desired.
JP 2002-38034 A (2nd page, claims) Japanese Patent No. 30433344 (first page, claims) Japanese Patent No. 312890 (first page, claims) Japanese Patent Laid-Open No. 6-49320 (first page, claims)

  The present invention provides a polyacetal resin composition and a sliding material that are excellent in slidability without impairing the original excellent mechanical properties of the polyacetal resin and that can achieve a high limit PV value in a high load / high speed region. The problem is to obtain parts.

As a result of intensive studies to solve the above problems, the present inventors have solved the above problems simultaneously by blending a specific graft copolymer , a specific polyethylene wax, and calcium carbonate or talc with a polyacetal resin. As a result, the present invention has been reached.

That is, the present invention relates to (B) a graft copolymer of (B) an olefinic (co) polymer and a vinylic polymer containing a hydroxyl group-containing vinylic monomer unit with respect to 100 parts by weight of the (A) polyacetal resin. 0.1 to 20 parts by weight , (C) 0.1 to 1.5 parts by weight of polyethylene wax made of polyethylene having a number average molecular weight of 1,000 to 5,000, and 0.5 to 0.5% of calcium carbonate or talc The present invention provides a polyacetal resin composition and a sliding component obtained by blending 30 parts by weight.

The polyacetal resin composition of the present invention is blended with a specific graft copolymer , a specific polyethylene wax, and calcium carbonate or talc in the polyacetal resin without impairing the original excellent mechanical properties of the polyacetal resin. Excellent sliding performance and high limit PV value in high load / high speed range, especially suitable for sliding parts such as gears, bearings and rails used at high loads and high speeds. is there.

  Hereinafter, the present invention will be described in detail.

  The polyacetal resin used in the present invention is a polymer having an oxymethylene unit as a main repeating unit and obtained by a polymerization reaction using formaldehyde or trioxane as a main raw material, so-called polyacetal homopolymer mainly consisting of oxymethylene units, It may be a so-called polyacetal copolymer containing 15% by weight or less of oxyalkylene units having 2 to 8 adjacent carbon atoms in the main chain. Further, it may be a copolymer containing other structural units, that is, a block copolymer, a terpolymer, or a crosslinked polymer. These can be used alone or in combination of two or more, and are preferably polyacetal copolymers from the viewpoint of thermal stability. If the comonomer amount is less than 0.3 mol%, the thermal stability tends to be insufficient, and if it exceeds 10 mol%, the mechanical strength tends to decrease, which is not preferable. A particularly preferable comonomer amount is 1.0 to 3.0 mol%.

  There is no restriction | limiting in particular in the manufacturing method of the polyacetal resin in this invention, It can manufacture by a well-known method. As an example of a typical method for producing a polyacetal homopolymer, high-purity formaldehyde is introduced into an organic solvent containing a basic polymerization catalyst such as an organic amine, an organic or inorganic tin compound, or a metal hydroxide. Examples of the method include polymerizing and filtering the polymer, followed by heating in acetic anhydride in the presence of sodium acetate to acetylate the polymer terminal.

  As a typical method for producing a polyacetal copolymer, a high purity trioxane, a copolymer component such as ethylene oxide or 1,3-dioxolane is introduced into an organic solvent such as cyclohexane, and boron trifluoride diethyl ether complex is prepared. After the cationic polymerization using a Lewis acid catalyst such as, the method of producing by deactivating the catalyst and stabilizing the end groups, or trioxane into the self-cleaning stirrer without using any solvent, Examples thereof include a method in which a copolymer component and a catalyst are introduced and bulk polymerization is performed, and then an unstable terminal is further decomposed and removed.

  The viscosity of these polymers is not particularly limited as long as it can be used as a molding material, but the melt flow rate (MFR) according to ASTM D1238 method (measurement conditions: temperature 190 ° C., load 2160 g) can be measured, The MFR is preferably in the range of 0.1 to 100 g / 10 min, particularly preferably 1.0 to 50 g / 10 min.

  Further, as the polyacetal resin, it is preferable to use a resin containing a heat stabilizer or a generated gas scavenger in advance.

The component (B) used in the present invention is a graft copolymer of an olefinic (co) polymer and a vinylic (co) polymer containing a hydroxyl group-containing vinylic monomer unit. Examples include those in which a polymer is a main chain and a vinyl (co) polymer containing a hydroxyl group-containing vinyl monomer unit forms a graft chain .

  Examples of olefinic (co) polymers that are the main chain of the graft copolymer include high-density polyethylene, medium-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, polypropylene, and polybutene. Examples thereof include copolymers and copolymers containing these as main components. Examples of the copolymer include an ethylene / propylene copolymer, an ethylene / butene copolymer, and an ethylene / octene copolymer. These olefin polymers can be polymerized by a multi-site catalyst typified by a known Ziegler catalyst and a single site catalyst typified by a metallocene catalyst.

The graft chain can be used vinyl-based (co) polymer containing a hydroxyl group-containing vinyl monomer units. The vinyl (co) polymer containing a hydroxyl group-containing vinyl monomer unit may be a polymer (homopolymer) or a copolymer (copolymer).

  The vinyl (co) polymer containing the hydroxyl group-containing vinyl monomer unit may be a vinyl (co) polymer comprising a hydroxyl group-containing vinyl monomer unit, or a hydroxyl group-containing vinyl monomer. It may be a vinyl copolymer comprising a body unit and other vinyl monomer units.

  Hydroxyl-containing vinyl monomers used for (co) polymerization of vinyl (co) polymers include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate etc. are mentioned, These can use 1 type, or 2 or more types.

  Specific examples of the other vinyl monomers include methacrylic acid esters such as methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and glycidyl methacrylate, acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and itacon. Examples thereof include unsaturated carboxylic acids such as acid and itaconic anhydride and anhydrides thereof, aromatic vinyl monomers such as styrene and methylstyrene, and vinyl cyanide monomers such as acrylonitrile. One or more of these other vinyl monomers can be used. The vinyl (co) polymer containing a hydroxyl group-containing vinyl monomer unit is preferably a styrene polymer, particularly preferably a styrene-hydroxyethyl methacrylate copolymer or a styrene-hydroxypropyl methacrylate copolymer.

Among the vinyl-based (co) polymer, styrene polymer are preferred, scan especially styrene - hydroxyethyl methacrylate copolymer, styrene - can be preferably used hydroxypropyl methacrylate copolymers.

  The method for producing the graft copolymer is not particularly limited, but can be prepared by a generally well-known radical reaction. For example, a method in which a radical catalyst is added to a monomer of an olefin polymer and a vinyl polymer or a vinyl copolymer and then melt-kneaded and graft copolymerized, or a peroxide in the olefin polymer or vinyl copolymer. Or the like to generate free radicals and melt-knead them with other components.

  Preferred specific examples of the graft copolymer include polyethylene-g-styrene polymer, polyethylene-g-styrene / hydroxyethyl methacrylate copolymer, polyethylene-g-styrene / hydroxypropyl methacrylate copolymer, polyethylene-g. -An acrylonitrile styrene copolymer etc. are mentioned ("-g-" shows graft copolymerization and "/" shows copolymerization.). In the above, the polyethylene may be low-density polyethylene or high-density polyethylene, but is particularly preferably low-density polyethylene.

  The proportion of the olefinic (co) polymer in the graft copolymer is preferably 10 to 95% by weight, more preferably 30 to 80% by weight. If the ratio of the polyolefin-based polymer is too small, the sliding characteristics tend to deteriorate, and if it is too large, the surface appearance of the composition tends to deteriorate.

  (B) The compounding quantity of a graft copolymer is 0.1-20 weight part with respect to 100 weight part of (A) polyacetal resin. Preferably it is 1-18 weight part, More preferably, it is 2-15 weight part. If the blending amount is less than 0.1 parts by weight, the effect of improving the friction and wear characteristics tends to be small. Conversely, if the blending amount exceeds 20 parts by weight, there is a tendency for mechanical properties and surface appearance to be decreased. Absent.

The (C) a polyethylene wax used in the present invention, polyethylene emission number, or means that they are of the type introduced with polar groups by acid-modified. The number average molecular weight is 1,000 to 5,000, more preferably 2,000 to 4,000. If the number average molecular weight is less than 1,000, burrs tend to occur on the surface of the molded product and during molding, and conversely, if it exceeds 5,000, the compatibility is lowered, delamination and surface appearance deteriorate. Neither is desirable because of the tendency to In the present invention, the number average molecular weight refers to a molecular weight in terms of polymethyl methacrylate (PMMA) measured by gel permeation chromatography.

Although not particularly limited production method of the above polyethylene wax, for example, a method of polymerization directly in Ziegler catalysts, a method for obtaining as a by-product at the time of high molecular weight polyethylene emissions Manufacturing, as a thermal decomposition product of high molecular weight polyethylene emissions obtaining method, processing said of polyethylene emissions carboxyl group by treatment with peroxide and oxygen, a method of obtaining by oxidation modification for introducing a polar group such as a carbonyl group or a hydroxyl group, the polyethylene emissions inorganic acids, organic acids, etc. Any production method such as a method obtained by acid modification by introducing a polar group such as a carboxyl group, a carbonyl group or a hydroxyl group is also included in the present invention. In the above, the polyethylene wax may be in a high density or low density, or may be in any physical state such as liquid, powder, flakes or lumps.

  (C) The compounding quantity of polyethylene wax is 0.1-1.5 weight part with respect to 100 weight part of (A) polyacetal resin, More preferably, it is 0.2-1.0 weight part. If the blending amount is less than 0.1 parts by weight, the effect of improving the friction and wear characteristics tends to be small. On the other hand, if it exceeds 1.5 parts by weight, there are problems such as deterioration of mechanical properties, delamination of molded products, and poor measurement. Neither is desirable because it occurs.

Furthermore, slidability can be further improved by blending calcium carbonate or talc with the polyacetal resin composition of the present invention . As the calcium carbonate, both light calcium carbonate and heavy calcium carbonate are preferably used. Such calcium carbonate or talc does not depend on the shape of the particle shape, fiber diameter, aspect ratio, etc. , and any of them can be used. The blending amount of calcium carbonate or talc is preferably 0.5 to 30 parts by weight, particularly preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polyacetal resin from the viewpoint that the effect of improving the slidability is remarkable. 0.5 to 10 parts by weight is most preferable. Even if the amount of calcium carbonate or talc is too small or too large, the effect of improving the slidability cannot be obtained sufficiently, which is not preferable.

  Various characteristics can be imparted to the polyacetal resin composition by further blending the polyacetal resin composition of the present invention with an additive depending on the application. Specifically, an antioxidant, a polymer or compound containing formaldehyde-reactive nitrogen, a formic acid scavenger, a weathering (light) stabilizer, a mold release (lubricant), a pigment, and the like are added in 100 parts by weight of the polyacetal resin of the present invention. The amount is preferably 0 to 5 parts by weight, particularly preferably 0.05 to 1.0 part by weight.

  As the antioxidant, a hindered phenol-based antioxidant is preferable. Specifically, for example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5′-) t-butyl-4′-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, 1,6-hexanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) -Propionate], triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], 2,2′-methylenebis- (4- Til-t-butylphenol), tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3- t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro (5,5) undecane, N, N′-bis-3 -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionylhexamethylenediamine, N, N'-tetramethylene-bis-3- (3'-methyl-5'-t-butyl- 4'-hydroxyphenol) propionyldiamine, N, N'-bis- [3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl] hydrazine, N-salicyloyl -N'-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N'-bis [2- {3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionyloxy} ethyl] oxyamide and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and tetrakis [methylene-3- (3 ′, 5′-di-t-butyl) -4′-hydroxyphenyl) propionate] methane. One type of these antioxidants may be used, or two or more types may be used in combination. Moreover, it is preferable to mix | blend 0.01-1 weight part with respect to 100 weight part of polyacetals.

  Examples of polymers or compounds containing formaldehyde-reactive nitrogen include nylon resins such as nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 12, and the like. Examples of the polymer include nylon 6 / 6-6 / 6-10 and nylon 6 / 6-12. Examples thereof include acrylamide and derivatives thereof, copolymers of acrylamide and derivatives thereof with other vinyl monomers, and compounds containing formaldehyde-reactive nitrogen atoms having amino substituents. Examples of copolymers of acrylamide and derivatives thereof with other vinyl monomers include poly-β-alanine copolymers obtained by polymerizing acrylamide and derivatives thereof with other vinyl monomers in the presence of metal alcoholates Can be mentioned. Examples of compounds containing formaldehyde-reactive nitrogen atoms having an amino substituent include guanamine (2,4-diamino-sym-triazine), melamine (2,4,6-triamino-sym-triazine), N- Butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N-diallylmelamine, N, N ′, N ″ -triphenylmelamine, N-methylolmelamine, N, N ′, N ″ -tri Methylolmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6-methyl-sym-triazine), 2,4-diamino-6-butyl-sym- Triazine, 2,4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butyl Xy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, 2, 4-dioxy-6-amino-sym-triazine, 2-oxy-4,6-diamino-sym-triazine, N, N, N ′, N′-tetracyanoethylbenzoguanamine, succinoguanamine, ethylene dimelamine, triguanamine And triazine derivatives such as melamine cyanurate, ethylene dimelamine cyanurate, triguanamine cyanurate, ammelin, and acetoguanamine. These polymers or compounds containing formaldehyde-reactive nitrogen may be used singly or in combination of two or more. Preferably it is 0.01-1 weight part with respect to 100 weight part of polyacetal resin.

  Examples of the formic acid scavenger include the above amino-substituted triazines and copolycondensates of amino-substituted triazines and formaldehyde, such as melamine-formaldehyde polycondensates. Other formic acid scavengers include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts, or alkoxides. For example, hydroxides such as sodium, potassium, magnesium, calcium, or barium, carbonates, phosphates, silicates, borates, and carboxylates of the above metals. The carboxylic acid is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted with a hydroxyl group. Examples of aliphatic carboxylic acids include capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosane Acid, montanic acid, melissic acid, laccelic acid, undecylenic acid, oleic acid, elaidic acid, cetreic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearolic acid, 12- Hydroxydodecanoic acid, 3-hydroxydecanoic acid, 16-hydroxyhexadecanoic acid, 10-hydroxyhexadecanoic acid, 12-hydroxyoctadecanoic acid, 10-hydroxy-8-octadecanoic acid, dl-erythro-9,10-dihydroxyoctadecane Etc. The. Among these, difatty acid calcium derived from a fatty acid having 12 to 22 carbon atoms is preferable, and specific examples include calcium dimyristate, calcium dipalmitate, calcium diheptadecylate, calcium distearate, (myristic acid-palmitic acid) calcium. , (Myristic acid-stearic acid) calcium, (palmitic acid-stearic acid) calcium, and the like. Particularly preferred are calcium dipalmitate, calcium diheptadecylate, and calcium distearate. In the present invention, it is particularly effective to blend 0.01 to 0.2 parts by weight with respect to 100 parts by weight of polyacetal.

  The weather resistance (light) stabilizer is preferably one or more selected from the group consisting of benzotriazole-based materials, oxalic acid anilide-based materials, and hindered amine-based materials.

  Examples of benzotriazole-based materials include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3,5-di-t-butyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-3,5-di-t-amylphenyl] benzotriazole, 2- (2′-hydroxy-3,5-di-isoamyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2 -(2'-hydroxy-4'-octoxyphenyl) benzotriazole, etc. Examples of oxalic acid alinide-based substances include 2-ethoxy-2. -Ethyl oxalic acid bisanilide, 2-ethoxy-5-t-butyl-2'-ethyl oxalic acid bisanilide, 2-ethoxy-3'-dodecyl oxalic acid bisanilide, etc. These substances may be used alone or in combination of two or more.

  Examples of hindered amine materials include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2, 6,6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2, 2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2 , 2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4- (ethylcarba Yloxy) -2,2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6 -Tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) -carbonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -oxalate, bis (2,2 , 6,6-tetramethyl-4-piperidyl) -malonate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis- (N-methyl-2,2,6,6-) Tetramethyl-4-piperidinyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis (2,2,6,6-tetramethyl) 4-piperidyl) -adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) -terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy)- Ethane, α, α′-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyltolylene-2 , 4-dicarbamate, bis (2,2,6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl-4-piperidyl ) -Benzene-1,3,5-tricarboxylate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate, 1- [2- { 3- (3,5-Di t-butyl-4-hydroxyphenyl) propionyloxy} butyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] 2,2,6,6-tetramethylpiperidine 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9- [2 , 4,8,10-tetraoxaspiro (5,5) undecane] diethanol and the like. Each of the hindered amine light stabilizers may be used alone or in combination of two or more.

  Among these, preferred weathering agents are 2- [2′-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-3,5-di-t-butylphenyl). ) Benzotriazole, 2- (2′-hydroxy-3,5-di-t-amylphenyl) benzotriazole, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis- (N -Methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 1,2,3,4-butanetetracarboxylic Acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β ′,-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5 , 5 Undecane is a condensation product of diethanol. These weather resistance (light) stabilizers are preferably blended in an amount of 0.1 to 1.0 part by weight based on 100 parts by weight of the polyacetal resin.

  Examples of the release agent include alcohols, fatty acids and esters thereof, polyoxyalkylene glycols, olefin compounds having an average polymerization degree of 10 to 500, higher fatty acid amides, and silicones. Of these, higher fatty acid amides are particularly preferred. As specific examples, stearylamide and ethylenebisstearylamide are preferred.

    In addition to the polyacetal resin composition of the present invention, inorganic pigments such as zinc sulfide, titanium oxide, barium sulfate, titanium yellow, and cobalt blue, and organic pigments such as condensed azo, perinone, phthalocyanine, and monoazo Etc. can be blended.

  The pigment is used in an amount of 0 to 5 parts by weight, preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the polyacetal resin. If it exceeds 5 parts by weight, the thermal stability is lowered, which is not preferable.

  Furthermore, in the polyacetal resin composition of the present invention, a nucleating agent, a plasticizer, a conductive material represented by conductive carbon black, metal powder, fiber and the like, a polyurethane-based elastomer, and a polyester, as long as the effects of the present invention are not impaired. Additives such as thermoplastic elastomers typified by thermoplastic elastomers, polystyrene-based elastomers, polyamide-based elastomers, adhesives, lubricants typified by metal soaps, hydrolysis resistance improvers, adhesion aids and the like can be blended.

  The manufacturing method of the polyacetal resin composition of this invention is not specifically limited, It can manufacture by a well-known method. For example, it can be produced by introducing each component into a device capable of melt-kneading polyacetal resin, specifically a batch mixer or kneader, continuous single-screw or twin-screw extruder, and melt-kneading.

  The polyacetal resin composition of the present invention can be easily molded by extrusion molding, injection molding, compression molding, vacuum molding, blow molding, foam molding, or the like.

  The mold temperature in the case of injection molding is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and even more preferably 80 ° C. or higher from the viewpoint of crystallization. On the other hand, from the viewpoint of deformation of the molded product, 140 ° C. or lower is preferable, 120 ° C. or lower is more preferable, and 110 ° C. or lower is even more preferable.

Molded articles obtained by molding by such a method are OA equipment, various mechanical parts of automobiles, such as rails , ratchets , copier gears, printer paper feed driving parts, toner stirring gear trains, CD or DVD players. or it can be used to mechanical parts such as parts of a disk drive, is particularly suitable for high load and sliding parts used at high speeds.

  Examples will be described below, but these examples do not limit the present invention.

Example 1 and Comparative Examples 1 to 9
Polyacetal resin (A), graft copolymer (B-1, B-2, B-3), polyethylene wax (C-1, C-2, C-3), inorganic compound (D-1, D-2) ) Were blended at the ratios shown in Table 1, and melt-kneaded at a cylinder temperature of 200 ° C. using a 30 mm diameter vented twin screw extruder to obtain pellets. Test pieces were prepared from the obtained resin composition by injection molding, and various evaluations were performed. These results are shown in Table 1 together with the prescription.

Comparative Examples 10-15
Polyacetal resin (A), graft copolymer (B-1, B-3), polyethylene wax (C-2, C-4), ethylenebisstearylamide (E-1) or montanic acid ester instead of polyethylene wax (E-2) was blended in the ratio shown in Table 2, and pellets were obtained in the same manner as in the examples. Test pieces were prepared from the obtained resin composition by injection molding, and various evaluations were performed. These results are shown in Table 2 together with the prescription.

  In addition, the characteristic of the resin composition shown to the Example and the comparative example was calculated | required according to the method shown next.

(1) Dynamic friction coefficient, specific wear amount Using an injection molding machine (Nissei Plastic Industry Co., Ltd., model PS-60E9ASE) with a clamping pressure of 60 tons, cylinder temperature 190 ° C, mold temperature 60 ° C, molding cycle The ring-shaped sliding test piece having an inner diameter of 19.0 mm, an outer diameter of 25.6 mm, and a height of 30 mm was formed in 25 seconds. The obtained test piece was allowed to stand in an environment of 23 ° C. and 50% RH for 24 hours, and the sliding friction material was a standard polyacetal resin (Toray Industries, Inc., trade name “Amirasu” S761). Using a testing machine (Orientec Co., Ltd., model EFM-III-EN), the dynamic friction coefficient and specific wear amount were evaluated at a surface pressure of 5 kg / cm ² , a linear velocity of 10 cm / s, and a contact area of 2.0 cm ² . .
Further, the stability (variation) of the dynamic friction coefficient at this time was evaluated in the following three stages.
A: Always constant and stable until the end of the test.
○: Basically stable, but may fluctuate slightly.
Δ: Fluctuation is slightly large.
X: Fluctuates greatly.

(2) Limit PV value Using the same tester, test piece and sliding mating material as in (1) above, the surface pressure is fixed at 5 kg / cm ² and the linear velocity is gradually increased from 1 cm / s. The condition where the test piece was melted was regarded as the limit PV value, and the product of the load and speed at that time was obtained.

(3) Surface state of molded product Using an injection molding machine (Nissei Plastic Industry Co., Ltd., model PS-60E9ASE) with a clamping pressure of 60 tons, cylinder temperature 190 ° C., mold temperature 60 ° C., injection pressure 400 kg / A square plate specimen (80 mm × 80 mm × 3 mm, film gate) was molded at cm ² and an injection speed of 3 cm / s, and the magnitude of peeling when the gate was cut was evaluated in the following three stages.
(Double-circle): It does not peel at all.
○: Peeling is difficult to occur, but if the gate cut speed is increased, peeling may occur slightly.
Δ: Some peeling is observed.
X: Exfoliation is seen largely.

On the other hand, the substances used in Examples and Comparative Examples are as follows.
(A) Polyacetal resin (made by Toray, trade name “Amirasu” S731)
(B-1) Polyethylene-g-styrene / hydroxypropyl methacrylate copolymer That is, 50 parts by weight of ultra-low density polyethylene (trade name “Naflex” DFDB1088, manufactured by Nippon Unicar Co., Ltd.), 34 parts by weight of styrene and 15 parts by weight of hydroxypropyl methacrylate The part was suspended in water and stirred at 75 ° C. for 2 hours. Next, 0.15 parts by weight of 3,5,5-trimethylhexanoyl peroxide and 0.4 parts by weight of t-butyl peroxide methacryloyloxyethyl carbonate were mixed with 1 part by weight of styrene and charged into the reaction mixture. The reaction was carried out at 70 ° C. for 4 hours. The obtained reaction product was washed with water, dried, and melt-extruded at 200 ° C. to produce graft copolymer B-1. Composition analysis was performed by pyrolysis gas chromatography. The weight ratio of polyethylene / styrene / hydroxypropyl methacrylate was 50/35/15.
(B-2) Polyethylene-g-acrylonitrile styrene copolymer (manufactured by NOF Corporation, trade name “Modiper” A1401)
(B-3) Polyethylene-g-polystyrene (Nippon Yushi Co., Ltd., trade name “Modiper” A1100)
(C-1) Polyethylene wax (Mitsui Chemicals, trade name “High Wax” 110P, molecular weight 1,000)
(C-2) Polyethylene wax (manufactured by LION CHEMTECH, trade name L-C 102N, molecular weight 2,500)
(C-3) Polyethylene wax (Mitsui Chemicals, trade name “High Wax” 420P, molecular weight 4,000)
(C-4) Polyethylene wax (product name “High Wax” 720P, molecular weight 7,400, manufactured by Mitsui Chemicals)
(D-1) Heavy calcium carbonate (Dowa Calfine Co., Ltd., trade name “KSS” -1000)
(D-2) Talc (Nihon Talc Co., Ltd., trade name “LMP” # 100)
(E-1) Ethylenebisstearylamide (product name “Armowax” EBS, manufactured by Lion)
(E-2) Montanate ester (trade name “Licowax” E, manufactured by Clariant Japan)

Claims (3)

(A) Graft copolymer of (B) olefin (co) polymer and vinyl (co) polymer containing a hydroxyl group-containing vinyl monomer unit with respect to 100 parts by weight of polyacetal resin 0.1 ~ 20 parts by weight, (C) 0.1 to 1.5 parts by weight of polyethylene wax made of polyethylene having a number average molecular weight of 1,000 to 5,000, and 0.5 to 30 parts by weight of calcium carbonate or talc Part of a polyacetal resin composition. A sliding part comprising the polyacetal resin composition according to claim 1 . 3. The sliding part according to claim 2 , wherein the sliding part is one of a rail, a ratchet, a copier gear, a printer paper feed driving part, a toner stirring gear train, a CD or DVD player, or a disk drive mechanism part.