JP2020026485A - Resin composition for slide member and slide member - Google Patents

Abstract

To provide a resin composition for slide members that can improve slide characteristics including low friction and wear resistance, without having any adverse effect on the mechanical strength and thermal characteristics of synthetic resin, and provide a slide member.SOLUTION: A resin composition for slide member has synthetic resin as the main component, as well as has, as additives, lubricant of 1-30 mass%, woody filler 0.25-32 mass%, polyolefin resin 0.65-36 mass% and compatibilizer 0.005-6.8 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition for a sliding member and a sliding member.

  Conventionally, synthetic resins such as polyamide resins, polyacetal resins, polyester resins, polyphenylene sulfide resins, and polyetheretherketone resins have excellent mechanical strength and thermal properties. Used for mechanical parts. However, these synthetic resins alone have a low limit PV value (the limit value of the load when the material melts or seizes due to friction when the bearing material exceeds a certain load (P) and speed (V)). That is, there is a disadvantage that the sliding characteristics are poor.

  In order to improve the sliding characteristics, a sliding member or a resin composition for a sliding member in which a synthetic resin is mixed with a lubricant such as a lubricating oil or a wax or a synthetic resin having low friction characteristics such as a polyethylene resin has been proposed. I have. For example, as a sliding member containing a lubricating oil such as a lubricating oil or a wax in a polyacetal resin, Patent Literature 1 discloses a method in which a thermoplastic synthetic resin made of a polyacetal resin or a polyamide resin is powdered and mixed with a lubricating oil. The lubricating oil is uniformly attached to the surface of the resin powder by stirring, and then the molding material supply section of the heating cylinder is kept at a low temperature equal to or lower than the melting point of the synthetic resin by cooling means, and the other portion of the cylinder is at least cooled. There has been proposed a method for producing a lubricating member such as a bearing, which is formed by melting and kneading with a granulator maintained at a temperature equal to or higher than the melting point of the synthetic resin into granules and molding the granules into a required shape as a forming raw material.

  Patent Document 2 discloses a synthetic resin composition in which a synthetic resin having low friction characteristics such as a polyethylene resin is blended with a polyacetal resin, and lubricating oil is mixed with an ultrahigh molecular weight polyethylene resin having an average molecular weight of 500,000 or more. The oil-impregnated plastic composition obtained by adding the mixture to one or more mixtures of synthetic resin materials such as polyamide resin and polyacetal resin and molding the same is disclosed in Patent Document 3, selected from polyacetal resin, polyamide resin and polyethylene terephthalate resin. The melt resistance of the crystalline thermoplastic resin and the powdered high-density polyethylene resin is mixed, and the powdered high-density polyethylene resin is contained in the crystalline thermoplastic resin as an independent phase. Patent Document 4 discloses a crystalline thermoplastic resin composition including a polyamide resin and a polyacetal resin. Patent Document 5 discloses a thermoplastic resin composition obtained by melt-kneading 70 to 98% by weight of a thermoplastic resin selected from a polyester resin and a polycarbonate resin and 30 to 2% by weight of an ultrahigh molecular weight polyethylene resin powder. Low friction and low wear polyacetal resin compositions containing 20 to 45% by weight of a polyethylene resin and 55 to 80% by weight of a polyacetal resin have been proposed.

JP-B-46-42217 Japanese Patent Publication No. 47-29374 Japanese Patent Publication No. 46-44456 JP-B-63-65232 JP-A-2002-105279

  However, in the sliding member described in Patent Literature 1, although sliding characteristics such as friction and wear are significantly improved, for example, a synthetic resin is selected as a sliding partner for the purpose of reducing the size and weight of the component, When the sliding friction between the synthetic resins occurs, stick-slip occurs, and it is not always sufficient to prevent the generation of squeak noise caused by the stick-slip. There is a problem that it is difficult to obtain a satisfactory molded product under normal molding conditions, for example, the molding conditions for obtaining are complicated, and it is necessary to control the temperature of each part of the molding machine during molding.

  In the sliding members made of the synthetic resin compositions described in Patent Documents 2 to 5, sliding characteristics such as friction and wear can be improved to some extent, but polyolefin resins have poor compatibility with polyacetal resins. As a result, the molded article may be peeled off in a layered form, and the appearance of the molded article may be impaired.

  The present invention has been made in view of the above-mentioned points, and its object is to include low friction and wear resistance without adversely affecting the mechanical strength and thermal properties of these synthetic resins. An object of the present invention is to provide a resin composition for a sliding member and a sliding member capable of improving sliding characteristics.

  The resin composition for a sliding member of the present invention comprises, in addition to a synthetic resin as a main component, 1 to 30% by mass of a lubricating oil as an additive, 0.25 to 32% by mass of a wood-based filler, and 0.65% of a polyolefin resin. -36% by mass and 0.005 to 6.8% by mass of a compatibilizer.

  According to the resin composition for a sliding member of the present invention, in the molding material comprising the resin composition for a sliding member, since the wood-based filler and the polyolefin resin absorb and retain the lubricating oil, the surface of the molding material can be lubricated. It has no stickiness due to oil, has good biteability into the screw of the molding machine, and has excellent molding workability. The surface of the molded product (sliding member) made of the molding material has no exfoliation and excellent surface condition. In addition, since the sliding member contains a lubricating oil and a wood-based filler uniformly dispersed therein, the sliding member has sliding characteristics including low friction and abrasion resistance. It can be greatly improved.

  The resin composition for a sliding member of the present invention comprises, as an additional component, a lubricating oil agent and a cellulose fiber which are in a liquid state at the time of molding and heating such as a natural wax, a hydrocarbon wax, a higher fatty acid and a wax obtained by inducing the higher fatty acid. May be contained at a ratio of 1 to 10% by mass. Since the lubricating oil that is in a liquid state at the time of molding heating plays a role of a retainer that absorbs and retains the lubricating oil that is in a liquid state at room temperature, it is blended as a lubricating oil in a sliding member made of the resin composition for a sliding member. The amount can be increased, and the slidability of the sliding member can be further improved. Moreover, the cellulose fiber can improve the mechanical strength and impact strength of the sliding member.

  A sliding member made of a molding material of the resin composition for a sliding member includes lubricating oil as an additive, a wood-based filler, a polyolefin resin, a compatibilizer, and a synthetic resin as a main component in a predetermined amount. Weigh them in proportions, mix them with a mixer to produce a mixture, and put the mixture into a vented single- or twin-screw extruder or a non-vented single- or twin-screw extruder to form a string. After molding into a molded article, the molded article may be cut into particle-shaped molding material pellets, and the molding material pellets may be formed by molding means using an injection molding machine or the like. The wood filler, the polyolefin resin, and the compatibilizer were each weighed at a predetermined ratio, and these were mixed with a mixer to prepare a mixture, and the mixture was charged into the screw-type extruder and melt-kneaded. Formed into a string-shaped molded product After that, the molded product is cut to produce a resin additive master batch pellet, and the resin additive master batch pellet, lubricating oil and synthetic resin are respectively weighed at predetermined ratios, and these are mixed by a mixer. After the mixture is poured into the screw-type extruder to form a cord-like molded product, the mixture is cut into particle-shaped molding material pellets, and this molding material pellet is injected into an injection molding machine. And the like.

  By forming the latter sliding member using a resin additive masterbatch pellet comprising a wood-based filler, a polyolefin resin, and a compatibilizer, segregation of the wood-based filler to the sliding member can be prevented. The wood filler can be uniformly dispersed, and there is an advantage that the surface of the produced sliding member does not peel and has an excellent surface state.

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition for sliding members and the sliding member which can improve the sliding characteristics including low friction property and abrasion resistance can be provided.

FIG. 1 is a perspective explanatory view for explaining a thrust test method.

  The resin composition for a sliding member of the present invention comprises, in addition to a synthetic resin as a main component, 1 to 30% by mass of a lubricating oil as an additive, 0.25 to 32% by mass of a wood-based filler, and 0.65% of a polyolefin resin. -36% by mass and 0.005 to 6.8% by mass of a compatibilizer.

  In the resin composition for a sliding member of the present invention, examples of the synthetic resin forming the matrix (main component) include a polyacetal resin, a polyamide resin, and an aliphatic polyketone resin.

  The polyacetal resin is a polymer compound having an oxymethylene group (—CH2O—) as a main constituent unit, and includes a polyacetal homopolymer composed of only oxymethylene units and a polyacetal copolymer containing oxymethylene units and comonomer units. . In the present invention, any of a polyacetal homopolymer and a polyacetal copolymer can be used as the polyacetal resin, but a polyacetal copolymer is preferred from the viewpoint of thermal stability.

  The molecular weight (number average molecular weight) of the polyacetal resin is not particularly limited as long as molding is possible, but is in the range of 20,000 to 80,000. The melt flow rate (MFR) according to the ASTM-D-1238 method can be measured, and a polyacetal resin having a MFR of 0.1 to 100 g / min measured at a temperature of 190 ° C. and a measurement load of 2160 g is preferable. Particularly preferred is a polyacetal resin having an MFR in the range of 1.0 to 5.0 g / 10 min.

  Specific examples of the polyacetal resin include a polyacetal homopolymer having a molecular weight of 50,000 to 70,000 (for example, “Delrin” (trade name, manufactured by Dupont, USA, “Tenac”, trade name, manufactured by Asahi Kasei Corporation), and a molecular weight of 50,000. (For example, trade name “Duracon” manufactured by Polyplastics Co., Ltd.).

  Examples of the polyamide resin (nylon) include aliphatic polyamide resins, and specifically, polycondensation of nylon 6 and undecane lactam (carbon number 11) synthesized by a polycondensation reaction of ε-caprolactam (carbon number 6). Nylon 11 synthesized by the reaction, Nylon 12 synthesized by a polycondensation reaction of lauryl lactam (C12), synthesized by co-condensation polymerization of hexamethylenediamine (C6) and sebacic acid (C10) And nylon 612 synthesized by a copolycondensation reaction between ω amino acids of caprolactam (carbon number 6) and lauryl lactam (carbon number 12).

  Specific examples of polyamide (nylon) resins include Nylon 6, Nylon 11, Nylon 12, and Nylon 610 (trade name "Amilan") manufactured by Toray, and Nylon 6, Nylon 11, Nylon 12, Nylon 612 (Dupont). Nylon 11 and Nylon 12 (trade name “Vestamide”) manufactured by Daicel Evonik, Nylon 11 and Nylon 12 (trade name “Rilsan”) manufactured by Arkema, and the like.

  The aliphatic polyketone resin is preferably represented by the following general formula (I). In the general formula (I), it is preferable that 80 mol% or more of R is a connecting group derived from ethylene.

〔（Ｉ）式中、Ｒはエチレン性不飽和化合物由来の連結基であり、各繰り返し単位において、同一であっても異なっていても良い。〕

[In the formula (I), R is a linking group derived from an ethylenically unsaturated compound, and each repeating unit may be the same or different. ]

Specific examples of the aliphatic polyketone resin include a polyketone resin manufactured by Hyosung (trade name “
Carilon ").

  In the resin composition for a sliding member of the present invention, as the lubricating oil as an additive, spindle oil, refrigerating machine oil, dynamo oil, turbine oil, machine oil, cylinder oil and paraffinic and naphthenic mineral oil such as gear oil, A lubricating oil that is liquid at room temperature selected from at least one of animal oils such as whale oil, vegetable oils such as castor oil and jojoba oil, esters, and synthetic oils such as polyglycol, polyphenyl ether, silicone and halocarbon. , About 15 to 27 ° C, generally about 20 ° C).

  The amount of the lubricating oil in the resin composition for a sliding member is 1 to 30% by mass, preferably 3 to 20% by mass. If the blending amount of the lubricating oil is less than 1% by mass, there is no effect on the improvement of the slidability, and if the blending amount exceeds 30% by mass, the mechanical properties of the sliding member obtained by molding are deteriorated and the surface appearance is deteriorated. There is a possibility that a lowering, poor biting into the screw, etc. may occur.

In the resin composition for a sliding member of the present invention, as the wood-based filler as an additive, conifers such as cedar, red pine, spruce pine, fir pine, beech pine, beetwort and cypress, and kiri, linden, beech, merkaba, wig, In addition to wood flour derived from broadleaf trees such as maple, mizunara and zelkova, powders derived from plant materials such as reeds, rice straw, rice husks and coconut, and plants such as bamboo, hemp, plants and agricultural products Powders such as materials are included. Further, as a wood-based filler, for example, wood board plywood, particle board (chip board), waste material of wood board such as MDF (Medium Density Fiberboard: medium density fiberboard) and OSB (Oriented Strand Board: oriented strand board), etc. May be broken by a cutter mill or the like, and then pulverized by a ball mill, an impeller mill, or the like to make a fine powder. The particle size of the wood-based filler is preferably about 100 to 500 μm, and the wood-based filler is sufficiently dried (having a water content of 3% by mass or less, further 2% by mass or less, especially 1% by mass). % Or less).

  The compounding amount of the wood-based filler in the resin composition for a sliding member is 0.25 to 32% by mass, and preferably 3 to 24% by mass.

  In the resin composition for a sliding member, the polyolefin resin as an additive has affinity (lipophilicity) with the lubricating oil, and as such a polyolefin resin, polyethylene, polypropylene, propylene-ethylene (block or random) Preferred examples thereof include a copolymer, an ethylene-propylene elastomer, an ethylene-propylene-dicyclopentadiene elastomer, an ethylene-acrylate copolymer, and an ethylene-vinyl acetate copolymer. Since these polyolefin resins have a melting point of 200 ° C. or less, it is possible to minimize the deterioration (decomposition) of the wood-based filler in the mixing step with the wood-based filler.

As the polyolefin resin, particularly, a low-density polyethylene resin (LDPE) having a high affinity (lipophilicity) with the lubricating oil, for example, having a density of 0.910 to 0.940 g / cm ³ , and having a density of 0.910 to 0.9. 930 g / cm ³ linear low density polyethylene resin (LLDPE), density 0.925-0.942 g / cm ³ medium density polyethylene resin (MDPE), density 0.940-0.970 g / cm ³ Polyethylene resins such as high-density polyethylene resin (HDPE) and ultrahigh molecular weight polyethylene resin having a molecular weight of 1,000,000 or more (UHMWPE) are preferably used.

  The compounding amount of the polyolefin resin in the resin composition for a sliding member is 0.65 to 36% by mass, preferably 1 to 10% by mass.

  In the resin composition for a sliding member, a compatibilizer as an additive is used to enhance the dispersibility of the wood-based filler in a polyolefin resin and a synthetic resin. The wood-based filler has many hydroxyl groups, and has a risk of agglomerating with each other during pulverization or mixing. By adding the compatibilizer, the surface of the wood-based filler is coated with the compatibilizer, the polyolefin resin and the synthetic resin and the wood-based filler become more familiar, and the dispersibility of the wood-based filler is improved. Is achieved.

  As the compatibilizer, a modified polyolefin resin obtained by graft-polymerizing a graft monomer such as an unsaturated carboxylic acid or a derivative thereof onto the polyolefin resin is used.

  Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid, furanic acid, pentenoic acid, vinyl acetic acid, monocarboxylic unsaturated carboxylic acid such as angelic acid, maleic acid, and chloroic acid. Maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, glutaconic acid, citraconic acid, endocis-bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic acid (trade name: nadic acid), methyl Dibasic unsaturated carboxylic acids such as endocis-bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic acid (trade name: methylnadic acid); tribasic acids such as citric acid and aconitic acid Unsaturated carboxylic acids.

  Examples of the unsaturated carboxylic acid derivatives include the above-mentioned monobasic, dibasic and tribasic unsaturated carboxylic acid derivatives, for example, acid halides, amides, imides, acid anhydrides, esters and salts (sodium salts and salts). Zinc salt and the like). Specific examples of such unsaturated carboxylic acid derivatives include maleenyl chloride, acrylamide, maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, maleic anhydride, itaconic anhydride, glutaconic anhydride, and citraconic anhydride. , Endocis-bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic anhydride (trade name: nadic anhydride), aconitic anhydride, methyl acrylate, methyl methacrylate, monomethyl maleate, Examples include dimethyl maleate, diethyl itaconate, dibutyl citraconic acid, glycidyl acrylate, glycidyl methacrylate, diglycidyl maleate, sodium acrylate and zinc acrylate.

  Among unsaturated carboxylic acids or derivatives of unsaturated carboxylic acids, acrylic acid, methacrylic acid, maleic acid, citric acid, sodium salts and zinc salts of these unsaturated carboxylic acids, maleic anhydride, itaconic anhydride and nadic anhydride are preferable.

  The grafting amount of the modifying monomer is 0.1 to 20 parts by mass (0.1 to 17% by mass), preferably 0.2 to 15 parts by mass (0.2 to 13% by mass) based on 100 parts by mass of the polyolefin resin. ), More preferably 0.3 to 10 parts by mass (0.3 to 9% by mass).

  A sliding member made of the resin composition for a sliding member having the above-mentioned composition has 1 to 30% by mass of a lubricating oil as an additive, 0.25 to 32% by mass of a wood-based filler, and 0.65 to 36% by mass of a polyolefin resin. % And a compatibilizer of 0.005 to 6.8% by mass and a synthetic resin as a main component in a predetermined ratio, respectively, and weigh them with a mixer such as a Henschel mixer, a super mixer, a ball mill and a tumbler mixer. After preparing a mixture, the mixture is charged into a vented single-screw or twin-screw extruder or a non-vented single-screw or twin-screw extruder, and melt-kneaded to form a cord-like molded product. The material is cut to produce particulate molding material pellets, and the molding material pellets are formed into a desired shape such as a cylindrical bush or a plate by a molding means such as an injection molding machine.

The sliding member made of the resin composition for a sliding member having the above component composition can be formed by the following method in addition to the above method. That is, the wood-based filler, the polyolefin resin, and the compatibilizer are weighed in advance at predetermined ratios, respectively, and they are mixed by the same mixer as in the above-mentioned production method, and the wood-based filler 5 to 80% by mass and the polyolefin are mixed. A mixture comprising 13 to 90% by mass of a resin and 0.1 to 17% by mass of a compatibilizer is prepared, and the mixture is charged into the same screw type extruder as described above, and is melt-kneaded to obtain a string-like molded product. Then, the molded product is cut to produce particulate pellets. This pellet becomes a resin additive masterbatch pellet diluted with a synthetic resin as a main component. Then, 1 to 30% by mass of lubricating oil and 5 to 40% by mass of resin additive master batch pellets (5 to 80% by mass of wood-based filler, 13 to 90% by mass of polyolefin resin and 0.1 to 17% by mass of compatibilizer) After preparing a mixture of a mass% and a synthetic resin whose balance is the main component with a mixer, the mixture is put into a screw type extruder similar to the above, melt-kneaded and molded into a cord-like molded product. The molded product is cut to produce particulate molding material pellets, and the molding material pellets are formed into a desired shape such as a cylindrical bush or a plate by a molding means such as an injection molding machine.

  In addition to the synthetic resin as the main component, 1 to 30% by mass of a lubricating oil as an additive, 0.25 to 32% by mass of a wood-based filler, 0.65 to 36% by mass of a polyolefin resin, and 0.005 to 5% of a compatibilizer According to the resin composition for a sliding member of the present invention containing 6.8% by mass, the molding material pellet made of the resin composition for a sliding member has no stickiness due to the lubricating oil on the surface of the molding material pellet, It has good penetration into the screw of the molding machine and excellent molding workability, and the surface of the molded product (sliding member) made of the molding material pellets has an excellent surface state without peeling. The sliding member obtained by molding a molding material pellet made of the resin composition for a sliding member contains a wood-based filler uniformly dispersed therein and contains a lubricating oil. The member has significantly improved sliding characteristics including low friction and wear resistance.

  In the resin composition for a sliding member of the present invention, at least one of a lubricating oil agent and a cellulose fiber which are in a liquid state at the time of molding and heating can be blended as an additional component.

  Examples of the lubricating oil agent that is in a liquid state when heated during molding include waxy substances such as natural waxes, hydrocarbon waxes, higher fatty acids, and waxes obtained by inducing higher fatty acids.

  Examples of the natural wax include montan wax and carnauba wax.

  Examples of the hydrocarbon wax include a paraffin wax having approximately 24 or more carbon atoms, an olefin wax having approximately 26 or more carbon atoms, an alkylbenzene having approximately 28 or more carbon atoms, and a microcrystalline wax. Specific examples of the hydrocarbon wax include paraffin wax “150” manufactured by Nippon Seiwa Co., Ltd., polyethylene wax “Ricowax PE520 (trade name)” manufactured by Clariant Japan Co., Ltd., and Nippon Seiro Co., Ltd. Microcrystalline wax "Hi-Mic-1080 (trade name)", "Hi-Mic-2045 (trade name)", "Hi-Mic-2095 (trade name)", "Luvax 2191 (trade name)" and Nikko Rica "Godes wax (trade name)", which is a mixture of polyethylene wax and paraffin wax manufactured by K.K.

  Higher fatty acids include higher saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, serotinic acid and montanic acid having approximately 12 or more carbon atoms, and olein having approximately 18 or more carbon atoms. And unsaturated fatty acids such as acids, linoleic acid, linolenic acid, elaidic acid, octadecenoic acid, arachidonic acid, cadoleic acid, erucic acid and parinaric acid.

  Examples of the wax obtained by deriving the higher fatty acid include higher fatty acid esters, higher fatty acid amides and higher fatty acid salts.

  The higher fatty acid ester is an ester of the higher fatty acid and a monohydric or polyhydric alcohol. Examples of the monohydric alcohol include capryl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and behenyl alcohol, and examples of the polyhydric alcohol include ethylene glycol, propylene glycol, butanediol, glycerin, pentaerythritol, and sorbitol. Is mentioned. Specific examples of higher fatty acid esters include stearyl stearate, pentaerythritol tetrastearate, monoglyceride stearate, monoglyceride behenate, and montanic acid wax.

  Examples of the higher fatty acid amide include saturated higher fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide and behenic acid amide, and unsaturated higher fatty acid amides such as erucic acid amide, oleic acid amide, brassic acid amide and elaidic acid amide. And higher fatty acid bisamides such as methylenebisstearic acid amide, ethylenebisstearic acid amide and ethylenebisoleic acid amide (including saturated or unsaturated higher fatty acid alkylamides such as higher fatty acid methylamide and higher fatty acid ethylamide).

  The higher fatty acid salt (metal soap) is a salt of the higher fatty acid with lithium, magnesium, calcium, barium, zinc or the like. Specific examples of the higher fatty acid salt include lithium stearate, calcium stearate, zinc stearate, and magnesium stearate.

One type of these lubricants may be used, or two or more types may be used in combination. When a lubricant which exhibits a liquid state at the time of molding heating and a lubricant which exhibits a liquid state at normal temperature are used in combination, the molding lubricant may be used. Since the lubricating oil that is in a liquid state at a temperature absorbs and holds the lubricating oil that is in a liquid state at normal temperature, the amount of the lubricating oil can be increased, and the sliding property of the sliding member can be further improved. Can be improved.

  The compounding amount of the lubricating oil agent which is in a liquid state when heated during molding is 0.1 to 10% by mass, and preferably 0.5 to 5% by mass. If the amount of the lubricating oil is less than 0.1% by mass, there is no effect on the improvement of the slidability, and if the amount exceeds 10% by mass, the mechanical properties of the sliding member obtained by molding are deteriorated or the surface is deteriorated. There is a possibility that the appearance may be deteriorated, the biting failure of the screw may occur, and the like.

  Cellulose fibers are dispersed and contained in a molded product (sliding member) made of the resin composition for a sliding member to improve mechanical strength and impact strength. Cellulose fibers include wood fibers (wood pulp such as conifers, hardwoods, etc.), bamboo fibers, sugarcane fibers, seed hair fibers (cotton linters, bon bucks cotton, kapok, etc.), and gin skin fibers (hemp, kozo, mitsumata, etc.). And natural cellulose fibers (pulp fibers) such as leaf fibers (such as Manila hemp, New Zealand hemp).

  The average fiber length (L) of the cellulose fibers is preferably from 0.1 to 100 µm, more preferably from 0.5 to 80 µm. The average fiber diameter (diameter: D) of the cellulose fibers is preferably 4 nm to 100 μm, and more preferably 4 nm to 90 μm. Further, the aspect ratio (L / D) of the cellulose fiber is preferably from 2 to 2,000, more preferably from 20 to 1,000.

  As a specific example of the cellulose fiber, for example, “Fluorene cellulose (trade name)” obtained by surface-treating hydrophilic cellulose with a hydrophobic fluorene group, manufactured by Osaka Gas Chemical Company, and the like can be given.

  The blending amount of the cellulose fiber is 1 to 10% by mass, preferably 3 to 5% by mass. If the compounding amount is less than 1% by mass, the effect of improving the mechanical strength and impact strength of the molded product is not exhibited, and if the compounding amount exceeds 10% by mass, the dispersibility in the molded product is impaired and segregation occurs. On the contrary, there is a possibility that the mechanical strength and impact strength of the molded product are reduced.

  The resin composition for a sliding member of the present invention includes a solid lubricant such as molybdenum disulfide, graphite, polytetrafluoroethylene, glass fiber, carbon fiber, and aramid, as long as the object of the present invention is not impaired. Fibers, fibrous substances such as potassium titanate fibers and whiskers, glass powder, and inorganic fillers such as talc, clay, calcium carbonate and zinc oxide can be added.

  Furthermore, the stability can be reinforced by adding various known stabilizers. In order to improve the properties according to the intended use, known additives can be blended. Examples of the additives include various coloring agents, release agents (other than the above-mentioned lubricants), antistatic agents and surfactants.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following examples, the friction and wear characteristics of the sliding member were evaluated by the following thrust test.

<Thrust test>
Test method: Under the test conditions shown in Tables 1 and 2, as shown in FIG. 1, a rectangular bearing test piece (sliding member) 1 having a side of 30 mm was fixed to a test table, and a cylindrical body serving as a mating material was fixed. While applying a predetermined load in a direction X perpendicular to the surface 3 from one side 3 of the bearing test piece 1 from 2, the cylinder 2 is rotated in a direction Y around an axis 4 of the cylinder 2, The coefficient of friction between the bearing test piece 1 and the cylindrical body 2 and the amount of wear on the surface 3 of the bearing test piece 1 after the test were measured. For the coefficient of friction, the coefficient of friction at the time of stability after 1 hour from the start of the test to the end of the test is shown. For the amount of wear, the dimensional change of the sliding surface after 8 hours of the test is shown. .

[Table 1]
<Thrust test: I>
Sliding speed 1m / min
Load (surface pressure) 100 kgf / cm ²
Test time 8 hours Specimen rectangular sliding member (30mm on each side)
Counterpart material Hollow cylindrical counterpart material [Stainless steel (SUS304), inner diameter 20 mm, outer diameter 25.6 mm, length 15 mm]
Lubrication No lubrication

[Table 2]
<Thrust test: II>
Sliding speed 20m / min
Load (contact pressure) 10kgf / cm ²
Test time 8 hours Specimen rectangular sliding member (30mm on each side)
Counterpart material Hollow cylindrical counterpart material [Stainless steel (SUS304), inner diameter 20 mm, outer diameter 25.6 mm, length 15 mm]
Lubrication No lubrication

  In the following examples, the synthetic resin forming the matrix, the lubricating oil presenting a liquid at normal temperature, the wood-based filler, the polyolefin resin, the compatibilizer, the cellulose fiber and the lubricating oil presenting a liquid at the time of molding and heating are shown below. Material used.

<Synthetic resin that forms the matrix>
(1) Polyacetal resin (“Duracon M90 (trade name) manufactured by Polyplastics Co., Ltd.)
")
(2) Polyamide resin (nylon 6: "Amilan CM (trade name)" manufactured by Toray Industries, Inc.)
(3) Aliphatic polyketone resin (polyketone resin manufactured by Hyosungu Co., Ltd. (trade name “Karilon”))
<Lubricant that is liquid at room temperature>
Jojoba oil (vegetable oil)
Turbine oil (mineral oil)
<Wood-based filler>
Wood flour (wood flour distributed in a particle size range of 100 to 500 μm and having a water content of 1% by mass or less)
<Polyolefin resin>
High density polyethylene resin (density 0.956 g / cm ³ )
<Compatibilizer>
Maleic acid-modified polyethylene resin (1 part by weight of maleic anhydride and 1 part by weight of lauroyl peroxide as a polymerization initiator are mixed with 100 parts by weight of high-density polyethylene resin, and the mixture is put in an autoclave and heated to 230 ° C. Maleic acid-modified polyethylene resin grafted with maleic acid
<Cellulose fiber>
Natural cellulose fiber having an aspect ratio (L / D) of 500 <lubricant that exhibits a liquid state when heated during molding>
Paraffin wax (hydrocarbon wax)

Examples 1 to 6
70% by mass of wood flour, 3% by mass of maleic acid-modified polyethylene resin and 27% by mass of high-density polyethylene resin were weighed and mixed with a tumbler mixer to prepare a mixture. This mixture was supplied to a twin-screw extruder equipped with a vent, melt-kneaded to form a cord-like molded product, and the molded product was cut to produce a particulate resin additive master batch pellet. The resin additive masterbatch pellets 2 to 20% by mass, jojoba oil 1 to 15% by mass, and polyacetal resin 65 to 97% by mass (remainder) are weighed, respectively, and mixed with a tumbler mixer to prepare a mixture. did. This mixture was supplied to a twin-screw extruder equipped with a vent, melt-kneaded to form a cord-like molded product, and then the molded product was cut to produce particulate molding material pellets. Next, the molding material pellets were supplied to a screw-type injection molding machine and injection-molded to produce a square shaped product (sliding member) having a size of 30 mm on a side and 3 mm in thickness. Tables 3 and 4 show Examples 1 to 6 of the component compositions of this sliding member.

Examples 7 and 8
The same resin additive master batch pellets as in Examples 1 to 6 were produced. 10% by mass of the resin additive master batch pellets, 5% by mass of jojoba oil, and 85% by mass of a polyamide resin or an aliphatic polyketone resin as a synthetic resin were weighed, and these were mixed with a tumbler mixer to prepare a mixture. . The mixture was supplied to a vented twin-screw extruder, melt-kneaded to form a cord-like molded product, and then cut to produce a particulate molding material pellet. Next, using this molding material pellet, a rectangular molded product (sliding member) having a size of 30 mm on a side and 3 mm in thickness was produced in the same manner as in Examples 1 to 6. The composition of the sliding member is shown in Examples 7 and 8 in Table 4.

Examples 9 to 17
The same resin additive master batch pellets as in Examples 1 to 6 were produced. 5 to 20% by mass of the resin additive master batch pellets, 3 to 5% by mass of turbine oil or jojoba oil, 3 to 5% by mass of paraffin wax and 3 to 5% by mass of natural cellulose fiber, and polyacetal Resins 71 to 89% by mass were weighed and mixed with a tumbler mixer to prepare a mixture. The mixture was supplied to a vented twin-screw extruder, melt-kneaded to form a cord-like molded product, and then cut to produce a particulate molding material pellet. Hereinafter, using this molding material pellet, a rectangular molded product (sliding member) having a size of 30 mm on a side and a thickness of 3 mm was produced in the same manner as in Examples 1 to 6. The composition of the sliding member is shown in Examples 9 to 17 in Tables 5 to 7.

Examples 18 to 22
Jojoba oil 3 to 30% by mass, wood flour 3.8 to 32% by mass, high density polyethylene resin 10 to 30% by mass, maleic acid-modified polyethylene resin 1.2 to 3.5% by mass, and polyacetal resin 50 ５９59.5% by mass, respectively, and these were mixed with a tumbler mixer to prepare a mixture. This mixture was supplied to a vented twin-screw extruder, melt-kneaded to form a cord-like molded product, and this molded product was cut to produce particulate molding material pellets. Hereinafter, using this molding material pellet, a rectangular molded product (sliding member) having a size of 30 mm on a side and a thickness of 3 mm was produced in the same manner as in Examples 1 to 6. The component compositions of this sliding member are shown in Tables 7 and 8 in Examples 18 to 22.

Examples 23 to 25
10% by mass of jojoba oil, 3.8% by mass of wood flour, 20% by mass of high density polyethylene resin, 2.5% by mass of maleic acid-modified polyethylene resin, 5% by mass of paraffin wax and 5% by mass of natural cellulose fiber At least one of them and 53.7 to 58.7% by mass of the polyacetal resin were respectively weighed and mixed with a tumbler mixer to prepare a mixture. This mixture was supplied to a vented twin-screw extruder, melt-kneaded to form a cord-like molded product, and this molded product was cut to produce particulate molding material pellets. Hereinafter, using this molding material pellet, a rectangular molded product (sliding member) having a size of 30 mm on a side and a thickness of 3 mm was produced in the same manner as in Examples 1 to 6. The component compositions of this sliding member are shown in Tables 8 and 9 in Examples 23 to 25.

Comparative Example 1
A particulate molding material pellet made of the same polyacetal resin as in the example was produced, and the molding material pellet was supplied to a vented twin-screw injection molding machine and injection-molded. The dimensions were 30 mm on a side and 3 mm in thickness. (Sliding member) having the following formula: The composition of this sliding member is shown in Comparative Example 1 in Table 9.

Comparative Example 2
97% by mass of polyacetal resin and 3% by mass of turbine oil as a lubricating oil as in the example were respectively weighed and mixed with a tumbler mixer to prepare a mixture. The mixture was vented to a twin-screw extruder equipped with a vent. The mixture was melt-kneaded to form a cord-like molded product, and then cut to produce a particulate molding material pellet. Hereinafter, a square shaped product (sliding member) having dimensions of 30 mm on a side and 3 mm in thickness was produced from the molding material pellets in the same manner as in the example. The composition of this sliding member is shown in Comparative Example 2 in Table 9.

Comparative Example 3
80 mass% of ultra high molecular weight polyethylene resin (“HIZEX Million (trade name)” manufactured by Mitsui Chemicals, Inc.) and 20 mass% of turbine oil as a lubricating oil are weighed and mixed with a tumbler mixer to form a mixture. This mixture is supplied to a vented twin-screw extruder, melt-kneaded to form a cord-like molded product, and then cut, and a resin containing 20% by mass of mineral oil and 80% by mass of ultra-high molecular weight polyethylene resin is added. An agent master batch pellet was prepared. 50% by mass of the resin additive master batch pellets and 50% by mass of the same polyacetal resin as in the example were weighed, and they were mixed with a tumbler mixer to prepare a mixture. The mixture was supplied to an extruder, melt-kneaded to form a cord-like molded product, and then cut to produce a particulate molding material pellet. Hereinafter, a rectangular molded product (sliding member) having a dimension of 30 mm on a side and a thickness of 3 mm was produced using the molding material pellets in the same manner as in the example. The composition of the sliding member is shown in Comparative Example 3 in Table 9.

  From the above test results, the sliding member according to the example can be used under the condition of high speed and low surface pressure (thrust test: II) even under the condition of low speed and high surface pressure (thrust test: I). It can be seen that even in use, it has excellent sliding characteristics including low friction and wear resistance. Further, it was visually confirmed that the sliding member according to the example had an excellent surface state without peeling on its surface.

  As described above, in the molding material comprising the resin composition for a sliding member of the present invention, since the wood-based filler and the polyolefin resin absorb and retain the lubricating oil, there is no stickiness due to the lubricating oil on the surface of the molding material, It has good penetration into the screw of the molding machine and excellent molding processability. The surface of the molded product (sliding member) made of the molding material is not exfoliated and becomes a molded product having an excellent surface state, Moreover, since the sliding member contains the wood-based filler uniformly dispersed and contains the lubricating oil, the sliding characteristics including low friction and wear resistance can be greatly improved. it can.

1 Bearing test piece (sliding member)
2 Cylindrical body (partner material)
3 planes 4 axis center

Claims (7)

  In addition to the synthetic resin as the main component, 1 to 30% by mass of a lubricating oil as an additive, 0.25 to 32% by mass of a wood-based filler, 0.65 to 36% by mass of a polyolefin resin, and 0.005 to 5% of a compatibilizer A resin composition for a sliding member containing 6.8% by mass.   The resin composition for a sliding member according to claim 1, wherein the synthetic resin is selected from a polyacetal resin, a polyamide resin, and an aliphatic polyketone resin. The resin composition for a sliding member according to claim 1 or 2, wherein the lubricating oil is a lubricating oil that is liquid at room temperature selected from at least one of paraffinic and naphthenic mineral oils, animal oils, vegetable oils, and synthetic oils.   The wood-based filler is a powder selected from at least one of wood, bamboo, rice straw, chaff, plywood, particle board, medium density fiber board (MDF), oriented strand board (OSB), and laminated wood. Item 4. The resin composition for a sliding member according to any one of Items 1 to 3.   The polyolefin resin is a polyethylene resin selected from a low density polyethylene resin, a linear low density polyethylene resin, a medium density polyethylene resin, a high density polyethylene resin and an ultra high molecular weight polyethylene resin. 4. The resin composition for a sliding member according to item 1.   Compatibilizers include acrylic acid, methacrylic acid, maleic acid, citric acid, and unsaturated carboxylic acids or unsaturated carboxylic acids, including sodium and zinc salts of these unsaturated carboxylic acids, maleic anhydride, itaconic anhydride and nadic anhydride. The resin composition for a sliding member according to any one of claims 1 to 5, comprising a modified polyolefin resin grafted with a monomer selected from an acid derivative. A sliding member comprising the resin composition for a sliding member according to any one of claims 1 to 6, wherein 1 to 30% by mass of a lubricating oil, 0.25 to 32% by mass of a wood-based filler, and polyolefin. Resin 0
. A sliding member comprising 65 to 36% by mass and 0.005 to 6.8% by mass of a compatibilizer dispersedly contained in a synthetic resin.

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