Resin composition for sliding member and sliding member

Abstract

To provide a resin composition for a slide member which is excellent in moldability and slide characteristics and contains a plant-derived polyethylene resin as a main component, and a slide member.SOLUTION: A resin composition for a slide member is blended with 0.1-20 mass% of a petroleum-derived polyethylene resin, 0.1-10 mass% of a modified polyolefin resin, 0.5-5 mass% of lubricating oil and 0.1-50 mass% of a plant-derived filler, as additives, in addition to a plant-derived polyethylene resin as a main component. A slide member is manufactured by molding the resin composition for the slide member.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition for sliding members containing a plant-derived polyethylene resin as a main component, and to a sliding member such as a bearing having excellent friction and wear properties. [Background technology]

[0002] In recent years, with growing awareness of the need to prevent global warming and reduce the use of petroleum, a defunct resource, attention has been focused on lactic acid polymers, which can be produced by lactic acid fermentation of raw materials such as sugars obtained by decomposing carbohydrates (such as starch) contained in grains, beans, and potatoes, or sugars contained in sugarcane, as well as plant-derived polyethylene resins, which are produced from ethylene extracted from bioethanol produced from raw materials such as corn.

[0003] For example, a biodegradable lubricating resin composition (Patent Document 1) has been proposed as a resin composition using a lactic acid polymer, which comprises an aliphatic polyester containing 50 to 100% by volume of a lactic acid component as the main component, and 5 to 30% by volume of one or more solid lubricants selected from the group consisting of tetrafluoroethylene resin, graphite, and mica. However, the polylactic acid resin that is the main component of this lubricating resin composition has low mechanical strength and is susceptible to hydrolysis, making it unsuitable for sliding applications.

[0004] In addition, a sliding part containing an inorganic filler and a polyamide containing units consisting of one type of dicarboxylic acid and one type of diamine has been proposed (Patent Document 2), in which plant-derived decamethylenediamine is used as the diamine to increase the biomass content. However, this sliding part may cause stick-slip (adhesion-slip) between the friction surfaces during sliding.

[0005] Meanwhile, as technologies using plant-derived polyethylene resins, packaging containers or packaging laminates using plant-derived polyethylene resins have been proposed in Patent Documents 3, 4, 5, and 6, etc., and some have been put to practical use. However, the fact is that no proposals have yet been made for use in sliding applications such as mechanical elements, for example, plain bearings. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-212400 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-129244 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-30942 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-231870 [Patent Document 5] Japanese Patent Application Publication No. 2018-135133 [Patent Document 6] Japanese Patent Application Publication No. 2019-34519 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, the present inventors have conducted extensive research into the application of plant-derived polyethylene resins to sliding applications, and have found that blending a predetermined amount of additive into plant-derived polyethylene resins makes them applicable to sliding applications, such as plain bearings. The present inventors have found that plant-derived polyethylene resins can be used in sliding applications, such as plain bearings, by blending a predetermined amount of additive into the plant-derived polyethylene resins. The present inventors have found that plant-derived polyethylene resins have excellent moldability and sliding properties. matrix The present invention provides a resin composition for a sliding member and a sliding member. [Means for solving the problem]

[0008] The resin composition for a sliding member of the present invention (hereinafter referred to as the resin composition) is matrix In addition to the plant-derived polyethylene resin, as an additive, Petroleum-derived polyethylene resin 0.1 to 20% by mass of polyethylene terephthalate, 0.1 to 10% by mass of modified polyolefin resin, 0.5 to 5% by mass of lubricating oil, and 0.1 to 50% by mass of plant-derived filler are blended, and the plant-derived polyethylene resin has a plant content of 80% or more. the law of nature, The petroleum-derived polyethylene resin is one or more resins selected from a high-density polyethylene resin, an ultra-high molecular weight polyethylene resin, and an acid-modified ultra-high molecular weight polyethylene resin, the modified polyolefin resin is selected from a polyolefin resin graft-modified with an unsaturated carboxylic acid, an anhydride thereof, or a derivative thereof, and a saponified polyolefin resin obtained by saponifying a polyolefin resin having an acetoxy group in the molecular chain with an alkali; The polyolefin resin graft-modified with the unsaturated carboxylic acid, its anhydride or a derivative thereof is selected from maleic anhydride-modified polypropylene resin, maleic anhydride-modified ethylene-α-olefin copolymer, and maleic anhydride-modified styrene-ethylene / butylene-styrene copolymer. .

[0009] According to the resin composition of the present invention, a molding material made of the resin composition has good bite into the screw of a molding machine and excellent moldability, and the surface of the molded product has an excellent surface condition. According to a sliding member made of the resin composition, the mechanical strength of the plant-derived polyethylene resin that is the main component can be improved, and in sliding friction with a mating member, sliding properties including low friction and wear resistance can be improved.

[0010] The resin composition of the present invention may contain, as additional components, a lubricant in an amount of 0.1 to 5% by mass and a colorant in an amount of 1 to 5% by mass.

[0011] The lubricant as an additional component serves as a mold release agent that improves the releasability of the resin composition from a mold during molding, and also serves as a carrier that absorbs and retains the lubricating oil, thereby suppressing the bleeding out of the lubricating oil. This not only allows the amount of lubricating oil to be increased, but also makes it possible to further improve the sliding properties of the sliding member by combining the lubricating oil and the lubricant. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a resin composition and a sliding member which have good molding processability, such as good bite into the screw of a molding machine, which can improve the mechanical strength of the plant-derived polyethylene resin that constitutes the main component, and which can also improve sliding properties, including low friction and wear resistance. [Brief explanation of the drawings]

[0013] [Figure 1]FIG. 1 is a perspective view illustrating a thrust test method. DETAILED DESCRIPTION OF THE INVENTION

[0014] The resin composition of the present invention contains, in addition to the plant-derived polyethylene resin as the main component, 0.1 to 20 mass% of a petroleum-derived polyethylene resin, 0.1 to 10 mass% of a modified polyolefin resin, 0.5 to 5 mass% of a lubricating oil, and 0.1 to 50 mass% of a plant-derived filler as additives.

[0015] In the resin composition of the present invention, the plant-derived polyethylene resin is a homopolymer of plant-derived ethylene derived from bioethanol obtained from plants such as sugarcane and corn, or a copolymer of this plant-derived ethylene with other monomers. The polymerization reaction from ethylene to polyethylene (PE) is similar to that in the polymerization of petroleum-derived ethylene.

[0016] Specific examples include high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene, and mixtures thereof, which are obtained by polymerizing plant-derived ethylene derived from bioethanol. Other monomers (comonomers) to be copolymerized with plant-derived ethylene are α-olefins having 3 to 20 carbon atoms, preferably 4 to 8 carbon atoms, and specific examples include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, and 4,4-dimethylpentene-1.

[0017] In the present invention, the plant-derived polyethylene resin has a density of 0.910 to 0.960 g / cm 3It is preferable that the plant-derived polyethylene has a plant content (%) (ASTM6866, measured by radioactive carbon 14C content) of 80% or more. When the plant content is 80% or more, it is possible to reduce CO2 emissions by approximately 70 to 74% compared to petroleum-derived polyethylene, making it possible to effectively use exhaustible resources and significantly reduce the amount of CO2 generated, which is a cause of greenhouse gases.

[0018] The melt flow rate of the plant-derived polyethylene resin (JIS K7210, temperature: 190°C, load: 2.16 kg) is preferably 0.5 to 10 g / 10 min from the viewpoint of extrusion processability, and more preferably 1.0 to 5.0 g / 10 min. If the melt flow rate is 0.5 to 10 g / 10 min, good extrusion processability can be maintained.

[0019] Specific examples of plant-derived polyethylene resins include Braskem's plant-derived high-density polyethylene (HDPE) resins "GREEN-SHE150, -SGF4960" (both trade names) and linear low-density polyethylene (LLDPE) resin "GREEN-SLH118." For sliding applications, however, plant-derived high-density polyethylene resins are preferably used.

[0020] The petroleum-derived polyethylene resin blended into the resin composition of the present invention is finely dispersed in the plant-derived polyethylene resin that constitutes the main component, and serves to improve the sliding properties, such as friction and wear, of a molded product (hereinafter referred to as a sliding member) made from the resin composition. Examples of petroleum-derived polyethylene resins that can be used include high-density polyethylene resins, ultra-high molecular weight polyethylene resins, and acid-modified ultra-high molecular weight polyethylene resins. As the acid-modified ultra-high molecular weight polyethylene resin, maleic anhydride-modified ultra-high molecular weight polyethylene resins are preferred.

[0021] High density polyethylene resin (HDPE) is a homopolymer of ethylene produced by a medium to low pressure method, and its density is usually 0.940 to 0.970 g / cm 3Examples of such ultra-high molecular weight polyethylene resins include "Hi-Zex (trade name)" manufactured by Prime Polymer Co., Ltd. and "Novatec (trade name)" manufactured by Japan Polyethylene Corporation. Examples of such ultra-high molecular weight polyethylene resins (UHPE) include those having an intrinsic viscosity [η] of 10 dL / g or more measured in decaphosphoric acid at 135°C and a viscosity-average molecular weight of 500,000 to 6,000,000. Examples of such ultra-high molecular weight polyethylene resins include "Hi-Zex Million (trade name)" manufactured by Mitsui Chemicals, Inc., "Mipelon (trade name)" manufactured by the same company, and "Sunfine (trade name)" manufactured by Asahi Kasei Chemicals Corporation. Examples of such ultra-high molecular weight polyethylene resins include those composed of an ultra-high molecular weight polyethylene resin having an intrinsic viscosity [η] of 10 to 40 dL / g at 135°C and a low- or high-molecular weight polyethylene resin having the same intrinsic viscosity [η] of 0.1 to 5 dL / g. Examples of such ultra-high molecular weight polyethylene resins include "Lubmer (trade name)" manufactured by Mitsui Chemicals, Inc. An example of an acid-modified ultra-high molecular weight polyethylene resin is "Modified LUBMER (trade name)" manufactured by Mitsui Chemicals, Inc., which is modified with maleic anhydride.

[0022] One or more petroleum-derived polyethylene resins are selected, and the blending amount is 0.1 to 20 mass %, preferably 0.5 to 15 mass %. A blending amount of less than 0.1 mass % is ineffective in improving the sliding characteristics of a sliding member made of the resin composition, while a blending amount of more than 20 mass % increases the melt viscosity of the resin composition during molding, tending to reduce flowability and potentially deteriorating the appearance of the molded product.

[0023] The modified polyolefin resin blended in the resin composition of the present invention is a modified polyolefin resin that can exhibit interaction with the plant-derived polyethylene resin that constitutes the main component, and serves as a compatibilizer that finely disperses the petroleum-derived polyethylene resin in the matrix of the plant-derived polyethylene resin that constitutes the main component and disperses a plant-derived filler, which will be described later, in the matrix of the plant-derived polyethylene resin, thereby significantly improving the sliding properties, including low friction and wear resistance, of a sliding member made from the resin composition, without reducing the mechanical strength.

[0024] The modified polyolefin resin is selected from polyolefin resins graft-modified with unsaturated carboxylic acids, their anhydrides, or derivatives, and saponified polyolefin resins obtained by saponifying polyolefin resins having acetoxy groups in the molecular chain with alkali. Examples of polyolefin resins include homopolymers of α-olefins, copolymers of two or more α-olefins, and copolymers of α-olefins with other compounds copolymerizable with the α-olefins. Examples of α-olefins include α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Examples of other compounds include compounds having polyunsaturated bonds, such as conjugated dienes and non-conjugated dienes, vinyl acetate, and acrylic esters.

[0025] Examples of suitable polyolefin resins include low-density, medium-density, or high-density polyethylene, linear low-density polyethylene, polypropylene, α-olefin copolymers (ethylene-propylene copolymers, ethylene-vinyl acetate copolymers (EVA), ethylene-butene copolymers, ethylene-hexene copolymers, ethylene-octene copolymers, ionically crosslinked olefin copolymers (ionomers)), and the like.

[0026] Unsaturated carboxylic acids, their anhydrides, or derivatives thereof are compounds having an ethylenically unsaturated bond and a carboxyl group, an acid anhydride, or a derivative group in one molecule. Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (Nadic acid), and methyl-endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (methylnadic acid); anhydrides of these unsaturated carboxylic acids; and derivatives such as unsaturated carboxylic acid halides, unsaturated carboxylic acid amides, and unsaturated carboxylic acid imides. More specifically, examples include malenyl chloride, maleimide, N-phenylmaleimide, maleic anhydride, itaconic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate, etc. Among these, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and itaconic anhydride are preferred, with maleic anhydride being particularly preferred.

[0027] Examples of maleic anhydride-modified polyolefin resins include maleic anhydride-modified polyethylene resins, maleic anhydride-modified polypropylene resins, maleic anhydride-modified ethylene-α-olefin copolymers (ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, ethylene-octene copolymers, etc.), and maleic anhydride-modified styrene-ethylene / butylene-styrene copolymers (SEBS).

[0028] A preferred example of the saponified polyolefin resin is a saponified ethylene-vinyl acetate copolymer.

[0029] The modified polyolefin resin used in the present invention preferably has a melt flow rate (MFR) of 0.1 to 100 g / 10 min, more preferably 0.1 to 50 g / 10 min, measured in accordance with JIS K7210 (2014) at a temperature of 190°C or 230°C under a load of 2.16 kg. If the MFR is less than 0.1 g / 10 min, the viscosity will be too high, resulting in poor fluidity of the resin composition and possibly worsening moldability in melt extrusion molding or the like. If the MFR is more than 100 g / 10 min, moldability will be unstable and the mechanical strength of the sliding member may be reduced.

[0030] Specific examples of modified polyolefin resins used in the present invention include maleic anhydride-modified polyethylene resins and maleic anhydride-modified polypropylene resins such as "ADMER (trade name)" manufactured by Mitsui Chemicals, Inc. and "MODIC (trade name)" manufactured by Mitsubishi Chemical Corporation; maleic anhydride-modified ethylene-propylene copolymers such as "TAFMER (trade name)" manufactured by Mitsui Chemicals, Inc.; maleic anhydride-modified ethylene-butene copolymers such as "TAFMER (trade name)" manufactured by Mitsui Chemicals, Inc.; maleic anhydride-modified styrene-ethylene / butylene-styrene copolymers such as "TUFTECH (trade name)" manufactured by Asahi Kasei Corporation, "SEPTON (trade name)" manufactured by Kuraray Co., Ltd., and "KRATON (trade name)" manufactured by Kraton Polymer Japan, Inc.; and saponified ethylene-vinyl acetate copolymers such as "TECHNOLINK (trade name)" manufactured by Taoka Chemical Co., Ltd., "MERCENE (trade name)" manufactured by Tosoh Corporation, "EVAL (trade name)" manufactured by Kuraray Co., Ltd., and "SOARNOL (trade name)" manufactured by Mitsubishi Chemical Corporation.

[0031] The blending amount of the modified polyolefin resin is 0.1 to 10% by mass, preferably 1 to 5% by mass. If the blending amount is less than 0.1% by mass, the effect of improving the mechanical strength, particularly the compressive strength, of the sliding member made of the resin composition, resulting in improved load resistance and sliding characteristics, is not exhibited, while if the blending amount exceeds 10% by mass, the moldability of the resin composition may be deteriorated.

[0032] The plant-derived filler blended in the resin composition of the present invention is dispersed and contained in a sliding member made of the resin composition, thereby improving the mechanical strength, particularly the compressive strength, of the sliding member and also serving as a carrier for absorbing and retaining the lubricating oil described below. The surface of this plant-derived filler is coated with the modified polyolefin resin that serves as the compatibilizer, improving compatibility with the resin composition and improving the dispersibility of the plant-derived filler.

[0033] Examples of plant-derived fillers include wood fibers (coniferous pulp such as red pine, black pine, Abies sachalinensis, Ezo spruce, red pine, larch, fir, hemlock, cedar, cypress, larch, Shirabe, spruce, hiba, Douglas fir, hemlock, white fir, spruce, balsam fir, cedar, pine, Merkusima pine, and Radiata pine, and mixtures thereof); hardwood pulp such as beech, birch, alder, oak, tabu, chinquapin, white birch, cottonwood, poplar, ash, mud willow, eucalyptus, mangrove, lauan, and acacia; pulp and mixtures thereof, bamboo fiber, sugarcane fiber, seed hair fiber (cotton fiber (cotton linter), kapok, etc.), ginseng bark fiber (hemp, paper mulberry, Mitsumata, etc.), leaf fiber (Manila hemp, sisal hemp, New Zealand hemp, rope hemp, etc.), fruit fiber (palm), cellulose fiber (pulp fiber) derived from natural plants such as rush and wheat straw, cellulose granules (powder), and cellulose nanofibers (cellulose nanofibers) produced by mechanically defibrating cellulose fiber as a raw material.

[0034] The average fiber length (L) of the cellulose fibers and cellulose nanofibers as plant-derived fillers is preferably 0.1 to 100 μm, more preferably 0.5 to 80 μm. The average fiber diameter (diameter: D) is preferably 4 nm to 100 μm, more preferably 4 nm to 90 μm, and the aspect ratio (L / D) is preferably 2 to 2,000, more preferably 20 to 1,000. The average particle diameter of the cellulose granules is 50 μm or less, preferably 40 μm or less. Fibers or granules with these properties can improve the dispersibility and affinity for plant-derived polyethylene resins, and can improve the mechanical strength, particularly the compressive strength, of sliding members made from the resin composition.

[0035] Specific examples of cellulose fibers and cellulose nanofibers as plant-derived fillers used in the present invention include "Fibra·Cel (trade name)" manufactured by Celite Corporation, "Nanoforest (trade name)" manufactured by Chuetsu Pulp Industries Co., Ltd., "BiNFi-s (trade name)" manufactured by Sugino Machine Ltd., "Cellenpia (trade name)" manufactured by Nippon Paper Industries Co., Ltd., "Celish (trade name)" manufactured by Daicel FineChem Ltd., and "Fluorene Cellulose (trade name)" manufactured by Osaka Gas Chemicals Co., Ltd. Specific examples of cellulose granules include "KC Flock (trade name)" manufactured by Nippon Paper Industries Co., Ltd., "Ceolas (trade name)" manufactured by Asahi Kasei Corporation, "Tosco Hemp Cellulose Powder, Tosco Silk Powder, Bamboo Powder (all trade names)" manufactured by Tosco Corporation, and "Cellulose Powder (trade name)" manufactured by TDI Corporation.

[0036] The blending amount of the plant-derived filler is 0.1 to 50% by mass, preferably 2 to 30% by mass. If the blending amount is less than 0.1% by mass, the effect of improving the strength of the sliding member made of the resin composition will not be exhibited, and if the blending amount exceeds 50% by mass, there is a risk of deterioration in moldability.

[0037] The lubricating oil blended in the resin composition of the present invention imparts low friction to the sliding member made of the resin composition, thereby improving the sliding properties.

[0038] Examples of lubricating oils include paraffinic and naphthenic mineral oils such as spindle oil, refrigeration oil, dynamo oil, turbine oil, machine oil, cylinder oil, and gear oil; animal oils such as whale oil; vegetable oils such as linseed oil, tung oil, castor oil, safflower oil, soybean oil, cottonseed oil, palm oil, rapeseed oil, and jojoba oil, which contain unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid as their main components; hydrocarbon synthetic oils such as α-olefin oligomers or hydrogenated products thereof, such as polybutene, polyisobutylene, 1-octene oligomer, 1-decene oligomer, and ethylene-propylene copolymer; and ether synthetic oils such as polyoxyalkylene glycol oil and polyphenyl ether oil.

[0039] The amount of lubricating oil blended is 0.5 to 5 mass %, preferably 1 to 3 mass %. If the blending amount is less than 0.5 mass %, it will not be effective in improving sliding properties, and if the blending amount is more than 5 mass %, there is a risk of a decrease in the mechanical strength of the sliding member, a deterioration in the surface appearance, poor screw bite, etc.

[0040] The resin composition of the present invention may contain additional components such as a lubricant and a colorant (pigment or dye).

[0041] When the lubricant is used in combination with the lubricating oil blended in the resin composition, the lubricant acts as a carrier that absorbs and retains the lubricating oil, so that the amount of the lubricating oil blended can be increased, and the sliding properties of the sliding member can be further improved.

[0042] The lubricant is a lubricant that assumes a liquid state when heated during molding, and examples thereof include waxy substances such as natural waxes such as montan wax and carnauba wax, hydrocarbon waxes, higher fatty acids, and waxes obtained by deriving higher fatty acids.

[0043] Examples of hydrocarbon waxes include paraffin wax, microcrystalline wax, polyethylene wax, and oxidized polyethylene wax.

[0044] Examples of higher fatty acids include higher saturated fatty acids having 10 or more carbon atoms, preferably 12 or more carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, arachidic acid, cerotic acid, montanic acid, and melissic acid; and unsaturated fatty acids having 12 or more carbon atoms, such as oleic acid, linoleic acid, linolenic acid, elaidic acid, octadecenoic acid, arachidonic acid, cadreic acid, erucic acid, and parinaric acid.

[0045] Examples of waxes obtained by deriving the above-mentioned higher fatty acids include higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

[0046] The higher fatty acid ester is an ester obtained by reacting the above-mentioned higher fatty acid with an aliphatic alcohol such as a monohydric saturated aliphatic alcohol, a monohydric unsaturated aliphatic alcohol, or a polyhydric alcohol.

[0047] Specific examples of higher fatty acid esters include esters of higher fatty acids having 12 to 26 carbon atoms, such as stearyl stearate and behenyl behenate, with monoalcohols having 12 to 24 carbon atoms; esters of alkylene diols having 2 to 6 carbon atoms, such as ethylene glycol mono- or dipalmitinate, ethylene glycol mono- or distearate, ethylene glycol mono- or dibehenate, and ethylene glycol mono- or dimontanate, with higher fatty acids having 12 to 26 carbon atoms; glycerin mono-, di-, or tripalmitinate; glycerin mono-, di-, or tristearate; Examples of the esters include mono-, di-, or triesters of alkanetriols (for example, glycerin) having 3 to 6 carbon atoms and higher fatty acids having 12 to 24 carbon atoms, such as tribehenate and glycerin mono-, di-, or trimontanate; and mono-, di-, tri-, or tetraesters of pentaerythritol and higher fatty acids having 14 to 24 carbon atoms, such as pentaerythritol mono-, di-, tri-, or tetrapalmitinate, pentaerythritol mono-, di-, tri-, or tetrastearate, pentaerythritol mono-, di-, tri-, or tetrabehenate, and pentaerythritol mono-, di-, tri-, or tetramontanate.

[0048] Examples of higher fatty acid amides include saturated higher fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide; unsaturated higher fatty acid amides such as erucic acid amide, oleic acid amide, brassidic acid amide, and elaidic acid amide; substituted amides such as N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and N-oleyl palmitic acid amide; methylol amides such as methylol stearic acid amide and methylol behenic acid amide; methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, and the like. Examples of the bisamide include saturated fatty acid bisamides such as phosphoric acid amide, ethylene bisstearic acid amide (ethylene bisstearylamide), ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N,N'-distearyl adipamide, and N,N'-distearyl sebacic acid amide; and unsaturated fatty acid bisamides such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide.

[0049] Higher fatty acid salts (metallic soaps) are salts of the above-mentioned higher fatty acids with alkali metals such as lithium, sodium, and potassium, alkaline earth metals such as magnesium, calcium, and barium, or zinc, and specific examples of higher fatty acid salts include lithium stearate, calcium stearate, magnesium stearate, and zinc stearate.

[0050] Specific examples of these lubricants include "Licowax (trade name)" manufactured by Clariant Chemicals as an oxidized polyethylene wax, which is a hydrocarbon wax; "Anstex (trade name)" manufactured by Toho Chemical Industry Co., Ltd. as a glycerin monostearate, which is a higher fatty acid ester; "Rikemal (trade name)" manufactured by Riken Vitamin Co., Ltd.; "Diamid (trade name)" manufactured by Mitsubishi Chemical Corporation as a higher fatty acid amide, lauric acid amide, palmitic acid amide; "Kaowax (trade name)" manufactured by Kao Corporation as an ethylene bisstearic acid amide; "Calcium Stearate" manufactured by Taihei Chemical Industry Co., Ltd. as a calcium stearate, which is a higher fatty acid salt; and "Zinc Stearate" manufactured by Nitto Kasei Kogyo Co., Ltd. as a zinc stearate.

[0051] The amount of lubricant to be blended is determined in consideration of the amount of lubricating oil blended, and is 0.1 to 5 mass %, preferably 0.5 to 3 mass %. If the blending amount is less than 0.1 mass %, the lubricant will not function as a carrier for absorbing and retaining the lubricating oil, while if the blending amount is more than 5 mass %, there is a risk of a decrease in the mechanical strength of the sliding member, a deterioration in the surface appearance, poor screw bite, etc.

[0052] The colorant is not particularly limited, but examples thereof include azo-based, anthraquinone-based, and triphenylmethane-based dyes, and pigments such as titanium oxide, cadmium sulfide, phthalocyanine, and carbon black. The blending amount is 1 to 5% by mass, and preferably 1 to 3% by mass. If the blending amount is less than 1% by mass, the colorant will not be effective, and if the blending amount is more than 5% by mass, the colorant may have a negative effect on the sliding properties of the sliding member.

[0053] The resin composition of the present invention can be easily prepared by a known method generally used for preparing conventional resin compositions. For example, a method may be used in which predetermined amounts of plant-derived polyethylene resin, petroleum-derived polyethylene resin, modified polyolefin resin, lubricating oil, and plant-derived filler as additives, or lubricant and colorant are weighed out and mixed in a mixer such as a Henschel mixer, super mixer, ball mill, or tumbler mixer to produce a mixture, which is then fed into a single- or twin-screw extruder, melt-kneaded to form a string-like molded product (strand), which is then cut into pellets, and the pellets are used as the molding material; or a method may be used in which predetermined amounts of petroleum-derived polyethylene resin, modified polyolefin resin, lubricating oil, and plant-derived filler as additives, or lubricant and colorant are weighed out and mixed in a mixer similar to the above to produce a mixture, which is then fed into a single- or twin-screw extruder, melt-kneaded to form a string-like molded product, which is then cut into pellets, and the pellets are then blended with the plant-derived polyethylene resin (the main component) in a predetermined ratio to produce the molding material.

[0054] The resin composition of the present invention has good bite into the screw of a molding machine and is excellent in moldability. A sliding member made of the resin composition can improve the mechanical strength of the plant-derived polyethylene resin and can also improve sliding properties, including low friction and wear resistance, in sliding friction with a mating material. [Example]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. Evaluation of the moldability of the resin composition into a molding material and the moldability of the molding material into a sliding member, as well as evaluation of the friction and wear properties of the sliding member made of the resin composition, were carried out by the following methods.

[0056] <Moldability (1)> The mixture (resin composition) was melt-kneaded using an extruder to form a string-like molded product, which was then cut to produce pellets.The string-like molded product was visually inspected for breakage (disconnection), screw penetration, and pellet surface condition (occurrence of voids (air bubbles), etc.), and evaluated according to the evaluation criteria in Table 1.

[0057] [Table 1]

[0058] <Moldability (2)> When a sliding member was molded from the pellets using an injection molding machine, the pellets were visually inspected for their bite into the screw, the releasability of the sliding member from the mold, and the surface condition (peeling, etc.) of the sliding member, and evaluated according to the evaluation criteria shown in Table 2.

[0059] [Table 2]

[0060] <Friction and wear characteristics> The friction coefficient and wear volume were measured using a thrust testing machine under the conditions shown in Table 3. The test method, as shown in Figure 1, involved fixing a rectangular bearing test piece (sliding component) 1, 30 mm on a side and 3 mm thick, to a test stand. A predetermined load was applied from a cylindrical body 2, which served as the mating material, to one surface 3 of the bearing test piece 1 in a direction X perpendicular to said surface 3, while the cylindrical body 2 was rotated in a direction Y around the axis 4 of the cylindrical body 2. The friction coefficient between the bearing test piece 1 and the cylindrical body 2 and the wear volume of surface 3 of the bearing test piece 1 after the test were measured. The friction coefficient was measured from one hour after the start of the test until the end of the test when stable, and the wear volume was measured as the amount of dimensional change of the sliding surface after 8 hours of testing.

[0061] [Table 3]

[0062] In the following examples, the plant-derived polyethylene resin, petroleum-derived polyethylene resin, modified polyolefin resin, lubricating oil, plant-derived filler, lubricant, and colorant used were as follows. Note that the following materials are all listed by their trade names. [A] Plant-derived polyethylene resin (A-1) Braskem's plant-based high-density polyethylene (HDPE) resin "GREEN-SHE150" with a density of 0.948 g / cm 3 MFR (Melt Flow Rate: Temperature 190°C, Load 2.16 kg) 1.0 g / 10 min [B] Petroleum-derived polyethylene resin (B-1) High-density polyethylene resin "Hi-Zex" manufactured by Prime Polymer Co., Ltd. (B-2) Ultra-high molecular weight polyethylene resin "Mipelon" manufactured by Mitsui Chemicals (B-3) Maleic anhydride modified ultra-high molecular weight polyethylene resin "Modified LUBMER" manufactured by Mitsui Chemicals, Inc. [C] Modified polyolefin resin (C-1) Saponified ethylene-vinyl acetate copolymer: "Technolink K431-80" manufactured by Taoka Chemical Co., Ltd. (vinyl acetate content before saponification: 28% by mass, degree of saponification: 80%, MFR: 4g / 10 min: 190°C, load: 2.16 kg) (C-2) Saponified ethylene-vinyl acetate copolymer: "MELTHEN H-6051" manufactured by Tosoh Corporation (vinyl acetate content before saponification: 28% by mass, degree of saponification: 100%, MFR: 5.5 g / 10 min: 190°C, load: 2.16 kg) (C-3) Maleic anhydride modified polyethylene resin "Admer NF518" manufactured by Mitsui Chemicals (MFR 2.2g / 10min: 230℃, load 2.16kg) (C-4) Maleic anhydride-modified ethylene-propylene copolymer "Tafmer MP0620" manufactured by Mitsui Chemicals (MFR 0.3 g / 10 min: 230°C, load 2.16 kg) (C-5) Maleic anhydride modified ethylene-butene copolymer "Tafmer MH7020" manufactured by Mitsui Chemicals (MFR 1.5g / 10min: 230℃, load 2.16kg) (C-6) Maleic anhydride-modified styrene-ethylene / butylene-styrene copolymer "Tuftec H1517" manufactured by Asahi Kasei Chemicals Corporation (MFR 3.0 g / 10 min: 230°C, load 2.16 kg) [D] Lubricating oil (D-1) Paraffin oil "Moresco White P-350P" manufactured by MORESCO (D-2) Hydrocarbon synthetic oil (ethylene-α-olefin oligomer) "Lucant" manufactured by Mitsui Chemicals (D-3) Vegetable oil (jojoba oil) "Jojoba Golden" imported by Mitsuba Trading Co., Ltd. [E] Plant-derived filler (E-1) Cellulose fiber "Fibra-Cel SW-10: plant-derived, average fiber diameter: 20 μm, average fiber length: 700 μm" manufactured by Celite Corporation (E-2) Cellulose nanofiber "Cerish KY-100G: average fiber diameter 100 nm" manufactured by Daicel FineChem Co., Ltd. (E-3) Powdered cellulose (wood pulp) "KC Flock: average particle size 37 μm" manufactured by Nippon Paper Industries Co., Ltd. (E-4) Bamboo fiber "Bamboo powder: average particle size 178 μm" manufactured by Naka Wood Co., Ltd. (E-5) Hemp Fiber "Tosco Hemp Cellulose Powder: Average Particle Size 22 μm" manufactured by Tosco Corporation (E-6) Wood powder: "Cedar powder: average particle size 178 μm" manufactured by Naka Wood Co., Ltd. [F] Lubricant (F-1) Hydrocarbon wax (oxidized polyethylene wax) "Licowax" manufactured by Clariant Chemicals (F-2) Higher fatty acid amide (ethylene bisstearic acid amide) "Kao Wax" manufactured by Kao Corporation (F-3) Higher fatty acid ester (glycerin monostearate) "Anstex" manufactured by Toho Chemical Industry Co., Ltd. [G] Colorant (G-1) Carbon Black: Ketjenblack manufactured by Lion Specialty Chemicals (G-2) Phthalocyanine Blue "Pigment Blue 15" manufactured by Tokyo Chemical Industry Co., Ltd.

[0063] Examples 1 to 20 The plant-derived polyethylene resin, which constitutes the main component, and the additives (B-1) to (B-3) petroleum-derived polyethylene resins, (C-1) to (C-6) modified polyolefin resins, (D-1) to (D-3) lubricants, (E-1) to (E-6) plant-derived fillers, (F-1) to (F-3) lubricants, and (G-1) and (G-2) colorants were prepared and weighed out in the amounts shown in Tables 4 to 7. These were then mixed in a tumbler mixer to produce a mixture, which was then fed into a twin-screw vent extruder, melt-kneaded to form a string-like molded product, and then cut into pellets. These pellets were used as molding materials. During this production process, the string-like molded product was visually observed for breakage (disconnection), screw penetration, and pellet surface condition (void formation, etc.). The results are shown in Tables 4 to 7.

[0064] Next, this molding material was fed into a screw-type injection molding machine and injection-molded to produce rectangular sliding members with dimensions of 30 mm on a side and 3 mm thick. During this manufacturing process, the pellets were visually inspected for their bite into the screw when molding the sliding members, the releasability of the rectangular sliding members from the mold, and the surface condition (peeling, etc.) of the sliding members, and the evaluation results are shown in Tables 4 to 7. In addition, the coefficient of friction and wear volume of the rectangular sliding members were evaluated according to the above-mentioned evaluation methods, and the results are shown in Tables 4 to 7.

[0065] Comparative Examples 1 to 4 The same plant-derived polyethylene resin as in the previous examples, the petroleum-derived polyethylene resin (B-3), the modified polyolefin resin (C-2), the lubricating oil (D-3), the plant-derived filler (E-3), the lubricant (F-3), and the colorant (G-1) were prepared and weighed out in the amounts shown in Table 7. These were then mixed in a tumbler mixer to produce a mixture, which was then fed into a twin-screw vent extruder, melt-kneaded to form a string-like molded product, and cut into pellets. These pellets were used as the molding material. During this production process, the string-like molded product was visually observed for breaks (disconnection), screw penetration, and pellet surface condition (voids, etc.). The evaluation results are shown in Table 8.

[0066] Next, this molding material was fed into a screw-type injection molding machine and injection-molded to produce rectangular sliding members with dimensions of 30 mm on a side and 3 mm thick. During this manufacturing process, the pellets were visually inspected for their bite into the screw when molding the sliding members, the releasability of the rectangular sliding members from the mold, and the surface condition (peeling, etc.) of the sliding members, and the evaluation results are shown in Table 8. The coefficient of friction and wear volume of the rectangular sliding members were also evaluated according to the above-mentioned evaluation methods, and the results are shown in Table 8.

[0067] [Table 4]

[0068] [Table 5]

[0069] [Table 6]

[0070] [Table 7]

[0071] [Table 8]

[0072] From the above test results, the resin compositions of Examples 1 to 20 had good screw bite during extrusion molding, and no breakage (cutting) of the string-like molded products was observed during the molding process of the string-like molded products. Furthermore, the molding material (pellets) formed from the string-like molded products had good bite into the screw of the injection molding machine, excellent moldability, no peeling on the surface of the molded product, and excellent surface condition. On the other hand, the resin compositions of Comparative Examples 1 to 3 had no particular problems with screw bite during extrusion molding, moldability of the string-like molded products, and moldability of the molding material formed from the string-like molded products. However, the resin composition of Comparative Example 4 had poor screw bite during extrusion molding, and a good string-like molded product could not be obtained.

[0073] Furthermore, all of the sliding members made from the resin compositions of Examples 1 to 20 exhibited low friction coefficients and small amounts of wear. In contrast, the sliding member made from the resin composition of Comparative Example 1 exhibited a high friction coefficient and very large amounts of wear. Furthermore, the sliding members made from the resin compositions of Comparative Examples 2 and 3 exhibited particularly large amounts of wear. For the resin composition of Comparative Example 4, a molding material could not be obtained, and therefore a sliding member could not be obtained, so a friction and wear property test was not performed. From the above, it can be seen that the sliding members made from the resin compositions of the Examples have superior sliding properties compared to the sliding properties of the sliding members made from the resin compositions of the Comparative Examples.

[0074] As described above, the resin composition and sliding member of the present invention have good bite into the screw of a molding machine, are excellent in molding processability, and have an excellent surface condition without peeling on the surface of the molded product. Furthermore, the sliding member made of the resin composition can provide a resin composition and sliding member that can significantly improve sliding characteristics including low friction and wear resistance in sliding friction with a mating material. [Explanation of symbols]

[0075] 1. Bearing test piece (sliding component) 2 Cylinder (mating material) 4 axis center

Claims

1. In addition to the plant-derived polyethylene resin matrix, As an additive, 0.1 to 20% by mass of petroleum-derived polyethylene resin, 0.1 to 10 mass% of modified polyolefin resin, 0.5 to 5% by weight of lubricating oil, and Contains 0.1 to 50% by mass of plant-derived filler, The plant-derived polyethylene resin has a plant content of 80% or more, The petroleum-derived polyethylene resin is one or more resins selected from a high-density polyethylene resin, an ultra-high molecular weight polyethylene resin, and an acid-modified ultra-high molecular weight polyethylene resin, the modified polyolefin resin is selected from a polyolefin resin graft-modified with an unsaturated carboxylic acid, an anhydride thereof, or a derivative thereof, and a saponified polyolefin resin obtained by saponifying a polyolefin resin having an acetoxy group in the molecular chain with an alkali; The polyolefin resin graft-modified with the unsaturated carboxylic acid, its anhydride, or a derivative thereof is selected from the group consisting of maleic anhydride-modified polypropylene resin, maleic anhydride-modified ethylene-α-olefin copolymer, and maleic anhydride-modified styrene-ethylene / butylene-styrene copolymer.

2. A resin composition for sliding members as described in claim 1, wherein the plant-derived polyethylene resin is made of a plant-derived high-density polyethylene resin.

3. The resin composition for a sliding member according to claim 1, wherein the saponified polyolefin resin comprises a saponified ethylene-vinyl acetate copolymer.

4. A resin composition for a sliding member according to any one of claims 1 to 3, wherein the plant-derived filler is selected from cellulose fibers, cellulose granules (powder), and cellulose nanofibers (cellulose nanofibers).

5. A resin composition for sliding members according to any one of claims 1 to 4, wherein the lubricating oil is selected from paraffinic and naphthenic mineral oils, animal oils, vegetable oils, hydrocarbon synthetic oils and ether synthetic oils.

6. 6. The resin composition for a sliding member according to claim 1, wherein a lubricant selected from natural waxes, hydrocarbon waxes, higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts (metallic soaps) is blended as an additional component in an amount of 0.1 to 5 mass%.

7. 7. The resin composition for a sliding member according to claim 1, further comprising, as an additional component, a colorant made of a dye or a pigment in an amount of 1 to 5% by mass.

8. A sliding member comprising the resin composition for a sliding member according to any one of claims 1 to 7.

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