Polyamide resin composition and sliding element

Abstract

The present invention provides a polyamide resin composition (nylon composition) and a sliding element using the same, which have excellent moldability and sliding performance. In addition to the main component polyamide resin, the polyamide resin composition also contains 5-20% by mass of polyethylene resin, 5-30% by mass of polytetrafluoroethylene resin, 0.5-5% by mass of modified polyolefin resin, and 1-5% by mass of phosphate as additives. The sliding element is produced by molding this polyamide resin composition.

Description

Technical Field

[0001] The present invention relates to a polyamide resin composition and a sliding element such as a bearing having excellent friction and wear characteristics. Background Art

[0002] Polyamide resins (hereinafter referred to as "nylon") are widely used in fields such as machining, automobiles, electrical / electronic parts, and home appliances due to their excellent moldability, heat resistance, toughness, chemical resistance, wear resistance, etc. However, since nylon alone cannot achieve sufficient friction and wear characteristics in sliding applications such as sliding bearings, it is essential to mix solid lubricants such as graphite, molybdenum disulfide, and polytetrafluoroethylene (hereinafter referred to as "PTFE") or lubricants such as mineral oil and wax.

[0003] For example, Patent Document 1 proposes a synthetic resin composition for sliding elements in which PTFE is blended with nylon for the purpose of imparting sliding properties to nylon. Furthermore, Patent Document 2 proposes a nylon composition in which molybdenum disulfide is blended with nylon.

[0004] However, nylon containing PTFE suppresses the reduction in rigidity during water absorption and improves friction and wear properties, but has the problem of significantly reduced heat resistance and mechanical strength. In addition, nylon containing molybdenum disulfide has the problem of reduced friction and wear properties due to the reduction in rigidity caused by water absorption.

[0005] To address the problem of decreased dimensional accuracy due to water absorption, a drawback of nylon itself, technologies have been proposed that incorporate inorganic fillers. However, when inorganic fillers are blended with nylon, there is a problem in that the inorganic fillers become abrasive particles due to wear and become embedded in the sliding surface when sliding against the mating material, causing wear.

[0006] It has been proposed to add polyethylene resin to nylon to improve wear. For example, Patent Document 3 proposes a resin composition containing nylon, an inorganic filler (mica), and a high-density polyethylene resin having a molecular weight of 50,000 to 400,000. Furthermore, Patent Document 4 proposes a nylon composition comprising nylon, wollastonite, a modified styrene-based copolymer, and a modified high-density polyethylene having a molecular weight of 50,000 to 400,000.

[0007] However, in Patent Document 3, the polyethylene resin-containing nylon tends to easily peel off the polyethylene resin from the surface layer of the molded product. Consequently, the molding conditions for obtaining a molded product with a good appearance are narrowed, and there is a problem of significant difficulty. Furthermore, in Patent Document 4, the inclusion of a modified styrene-based copolymer and a modified high-density polyethylene causes a problem in that the flowability during molding deteriorates, resulting in poor moldability.

[0008] Citation list

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2-219849

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 63-207851

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 5-263560

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 6-345961 Summary of the Invention

[0014] Technical issues

[0015] Previously proposed nylon compositions have severe molding conditions when molded, and molded products (sliding elements) made from such nylon compositions have insufficient friction and wear characteristics. In view of the above circumstances, an object of the present invention is to provide a nylon composition (polyamide resin composition) and a sliding element having excellent moldability and sliding properties.

[0016] Problem Solution

[0017] The nylon composition of the present invention contains, in addition to the main component nylon, as additives, 5-20% by mass of polyethylene resin, 5-30% by mass of polytetrafluoroethylene resin, 0.5-5% by mass of modified polyolefin resin, and 1-5% by mass of phosphate.

[0018] The nylon composition of the present invention provides a molding material having good screw biting properties for a molding machine and excellent molding processability. Furthermore, the molded product exhibits excellent surface condition due to the absence of peeling on its surface. Sliding elements made from this nylon composition do not impair the initial mechanical properties of nylon and can significantly improve sliding characteristics, including low friction and wear resistance, with respect to sliding friction between opposing elements.

[0019] The nylon composition of the present invention may contain as additional components 0.1-1% by mass of a lubricant and 0.1-2% by mass of an antioxidant. Furthermore, the nylon composition of the present invention may contain as additional components 1-40% by mass of organic particles or organic fibers.

[0020] The lubricant, a separate component, acts as a release agent, improving the release properties of the nylon composition from the mold during molding. Furthermore, the antioxidant is used to prevent oxidative degradation of the nylon composition during molding. Furthermore, the organic particles or fibers significantly improve sliding properties, including low friction and wear resistance, without reducing the mechanical strength of the molded product (sliding element) made of the nylon composition.

[0021] Beneficial effects of the present invention

[0022] According to the present invention, a nylon composition and a sliding element can be provided which have good molding processability such as biting performance into a screw of a molding machine and which have significantly improved sliding properties including low friction and wear resistance without impairing the initial mechanical properties of nylon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A perspective illustration used to explain the jab test method. DETAILED DESCRIPTION

[0024] The nylon composition of the present invention contains, in addition to the main component polyamide resin, 5-20 mass % of polyethylene resin, 5-30 mass % of polytetrafluoroethylene resin, 0.5-5 mass % of modified polyolefin resin, and 1-5 mass % of phosphate as additives.

[0025] In the nylon composition of the present invention, the main component nylon is a polymer having an amide bond (-NH-CO-) in the main chain and is a polymer containing structural units derived from monomer components such as aminocarboxylic acid (amino acid), diamine and dicarboxylic acid. The nylon may be composed of one type of structural unit (polymer of aminocarboxylic acid) or a plurality of types of structural units (copolymer of diamine and dicarboxylic acid, copolymer of diamine, dicarboxylic acid and aminocarboxylic acid, etc.).

[0026] Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, p-aminobenzoic acid, and p-aminomethylbenzoic acid. Examples of lactams include ε-caprolactam, undecanoic acid, and ω-laurolactam. These can be used alone or in combination of two or more.

[0027] Examples of the diamines include aliphatic diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine (1,7-diaminoheptane), octamethylenediamine (1,8-diaminooctane), nonamethylenediamine (1,9-diaminononane), decamethylenediamine (1,10-diaminodecane), undecamethylenediamine (1,11-diaminoundecane), dodecamethylenediamine (1,12-diaminodecane), and 1,13-diaminooctane. dodecane), tridecamethylenediamine, tetradecamethylenediamine, pentadecamethylenediamine, hexadecamethylenediamine, heptadecamethylenediamine, octadecamethylenediamine, nonadecamethylenediamine, eicosamethylenediamine, 2-methyl-1,5-diaminopentane, 3-methyl-1,5-diaminopentane, 2-methyl-1,8-octanediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine and 5-methyl-1,9 -nonanediamine, etc.; alicyclic diamines such as 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)propane, bis(3-methyl-4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)propane, 1,3-bisaminomethylcyclohexane, 1,4-bisamino

[0014] Examples of the present invention include 2-amino-3-methyl-1-cyclopentamethylamine, 5-amino-2,2,4-trimethyl-1-cyclopentamethylamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone diamine), bis(aminopropyl)piperazine, bis(aminoethyl)piperazine, norbornane dimethyleneamine, and tricyclodecane dimethylamine; and aromatic diamines such as p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, p-xylylenediamine, o-xylylenediamine, and m-xylylenediamine. These can be used alone or in combination of two or more.

[0028] Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid and eicosanedioic acid; alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid and norbornanedicarboxylic acid; aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid. These can be used alone or in combination of two or more.

[0029] Specific examples of nylon used in the present invention include aliphatic nylons having a melting point of 150° C. or higher and excellent heat resistance and strength such as polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sebacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecylamine ...pentamethylene adipamide (nylon 610), polypentamethylene adipamide (nylon 610), polyhexamethylene dodecylamine (nylon 610), polyhexamethylene dodecylamine (nylon 610), polyhexamethylene dodecylamine (nylon 610), polypentamethylene adipamide (nylon 610), polypentamethylene dodecylamine (nylon 610), polypentamethylene adipamide (nylon 610), polypentamethylene dodecylamine (nylon 610), polyhexamethylene dodecylamine (nylon 610), 12), polydecamethylene adipamide (nylon 106), polydecamethylene sebacamide (nylon 1010), polydecamethylene dodecamethylene (nylon 1012), polyundecanamide (nylon 11), polydodecaneamide (nylon 12), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), and the like, and semi-stable diamines obtained by polymerization of aliphatic and / or alicyclic diamines and aromatic carboxylic acids, aromatic diamines and aliphatic and / or alicyclic dicarboxylic acids, mixtures thereof, or lactams or aminocarboxylic acids thereof Aromatic nylons such as polyhexamethylene terephthalamide (nylon 6T), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6 I), polyhexamethylene terephthalamide / polyundecanamide copolymer (nylon 6T / 11), polyhexamethylene terephthalamide / polydodecaneamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyxylylene adipamide (nylon XD6), polyxylylene sebacate (nylon XD10), polymethylene xylylene adipamide (nylon MXD 6), polymethylene xylylene sebacate (nylon MXD10), polynonamethylene terephthalamide (nylon 9T), polydecamethylene terephthalamide (nylon 10T), polyundemethylene terephthalamide (nylon 11T), and polydodecamethylene terephthalamide (nylon 12T), etc.

[0030] In the present invention, among the different nylons mentioned above, plant-derived nylon can be used. Plant-derived nylon is a resin using monomers obtained from plant-derived components such as vegetable oils. Therefore, from the perspective of environmental protection (carbon neutrality perspective), plant-derived nylon is desirable. Examples of plant-derived nylon include nylon 11 (which has a structure in which a monomer having 11 carbon atoms (aminoundecanoic acid) is bound via an amide bond), nylon 610 (which has a structure in which a monomer having 6 carbon atoms (hexamethylenediamine) and a monomer having 10 carbon atoms (sebacic acid) are bound via an amide bond), nylon 612 (which has a structure in which a monomer having 6 carbon atoms (hexamethylenediamine) and a monomer having 12 carbon atoms (dodecanedioic acid) are bound via an amide bond), Nylon 1010 (which has a structure in which a monomer having 10 carbon atoms (decamethylene diamine) and a monomer having 10 carbon atoms (sebacic acid) are bound via an amide bond), nylon 1012 (which has a structure in which a monomer having 10 carbon atoms (decamethylene diamine) and a monomer having 12 carbon atoms (dodecanedioic acid) are bound via an amide bond), and nylon 10T (which has a structure in which a monomer having 10 carbon atoms (decamethylene diamine) and terephthalic acid are bound via an amide bond).

[0031] The PTFE incorporated into the nylon composition of the present invention is used to impart low friction properties to sliding elements made from the nylon composition. PTFE is divided into two types: PTFE used for molding (molding powder, fine powder) and PTFE used as a lubricant additive. PTFE used for molding typically has a molecular weight of several million to ten million (high-molecular-weight PTFE) and tends to become fibrous when subjected to stress before sintering. For this reason, it cannot be used as a lubricant additive. Therefore, in the present invention, the lubricating PTFE used is, for example, low-molecular-weight PTFE with a molecular weight of several hundred thousand or less to suppress fibrosis, or the high-molecular-weight PTFE is pulverized after molding and sintering.

[0032] Examples of PTFE used for lubricating additives include “TLP 10F-1 (trade name)” manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd., “Lubron L-5 (trade name)” manufactured by DAIKIN INDUSTRIES, LTD., “Fluon Fluon L 150J (trade name)”, “Fluon L169J (trade name)”, “Fluon L170J (trade name)” manufactured by AGC Inc., “KTL620 (trade name)”, “KTL610 (trade name)”, “KT300M (trade name)”, “KT400M (trade name)”, “KT600M (trade name)” and the like manufactured by KITAMURA LIMITED, and “TF9201Z (trade name)”, “TF9202Z (trade name)”, “TF9027Z (trade name)” and the like manufactured by 3M Company.

[0033] The PTFE content is 5-30% by mass, preferably 10-25% by mass. If the content is less than 5% by mass, low friction is insufficient. On the other hand, if the content exceeds 30% by mass, the moldability of the resin composition for the sliding element may deteriorate.

[0034] The polyethylene resin incorporated into the nylon composition of the present invention is used to improve the sliding properties, such as friction and wear characteristics, of a sliding element made from the nylon composition. Examples of the polyethylene resin include high-density polyethylene resins, ultra-high molecular weight polyethylene resins, and acid-modified ultra-high molecular weight polyethylene resins. The acid-modified ultra-high molecular weight polyethylene resin is preferably a maleic anhydride-modified ultra-high molecular weight polyethylene resin.

[0035] High-density polyethylene resin (HDPE) is an ethylene homopolymer produced by a medium / low pressure process and its density is typically 0.940-0.970 g / cm 3. Examples of the high-density polyethylene resin include “HI-ZEX (trade name)” manufactured by Prime Polymer Co., Ltd., “Novatec (trade name)” manufactured by Japan Polyethylene Corporation, and the like. As the ultra-high molecular weight polyethylene resin (UHPE), a polyethylene resin having a final viscosity [η] measured in a decanoic acid solvent at 135° C. of 10 dl / g or more and a viscosity-average molecular weight of 500,000 to 6,000,000 can be used. Examples of the ultra-high molecular weight polyethylene resin include “HI-ZEX Million (trade name)” manufactured by Mitsui Chemicals, Inc., “MIPELON (trade name)” manufactured by Mitsui Chemicals, Inc., and “SUNFINE (trade name)” manufactured by Asahi Kasei Corp. Furthermore, as the ultra-high molecular weight polyethylene resin, a polyethylene resin composed of an ultra-high molecular weight polyethylene resin (whose final viscosity [η] at 135° C. is 10 to 40 dl / g) and a low molecular weight or high molecular weight polyethylene resin (whose final viscosity [η] at 135° C. is 0.1 to 5 dl / g) can be used. Examples of the ultra-high molecular weight polyethylene resin include “Lubmer (trade name)” manufactured by Mitsui Chemicals, Inc. Examples of the acid-modified ultra-high molecular weight polyethylene resin include “Modified lubemer (trade name)” manufactured by Mitsui Chemicals, Inc., which is modified with maleic anhydride.

[0036] In addition, in the present invention, a homopolymer of plant-derived ethylene derived from bioethanol obtained from plants such as sugarcane and corn, or a copolymer of such plant-derived ethylene and another monomer can be used as the polyethylene resin. When a plant-derived nylon having a biomass content of 100% or less is used as the nylon (which is the main component of the plant-derived polyethylene resin), the plant-derived nylon serves to improve the biomass content of the nylon composition. Examples of such plant-derived polyethylene resins include the green polyethylenes "SLL118, SLL218, SGM9450F, SHA7260, SHE150, SGF4950 (all trade names)" manufactured by Braskem SA.

[0037] The polyethylene resin is selected from one or two or more of the above-mentioned types and is blended in an amount of 5 to 20% by mass, preferably 5 to 15% by mass. If the blending amount is less than 5% by mass, there is no effect on improving the sliding characteristics of the sliding element made of the nylon composition. On the other hand, if the blending amount exceeds 20% by mass, the dispersion ratio in the nylon as the main component increases, so the wear resistance may deteriorate.

[0038] The modified polyolefin resin incorporated into the nylon composition of the present invention is a modified polyolefin resin into which acid groups are introduced. These acid groups are capable of interacting with nylon, the main component of the nylon composition. The modified polyolefin resin acts as a compatibilizer, finely dispersing the polyethylene resin, which is insoluble in nylon, within the nylon matrix. Furthermore, the modified polyolefin resin significantly improves sliding properties (including low friction and wear resistance) without reducing the mechanical strength of molded products (sliding elements) made from the nylon composition.

[0039] The modified polyolefin resin is selected from unsaturated carboxylic acids, polyolefin resins graft-modified with their anhydrides or derivatives, and saponified polyolefin resins obtained by saponifying a polyolefin resin having an acetoxy group in its molecular chain with an alkali. Examples of polyolefin resins include homopolymers of α-olefins, copolymers of two or more types of α-olefins, or copolymers of α-olefins and other compounds capable of copolymerizing with 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, and examples of other compounds include vinyl acetate, acrylic acid esters, and compounds having polyunsaturated bonds such as conjugated dienes and non-conjugated dienes.

[0040] Suitable examples of polyolefin resins include low-density, medium-density or high-density polyethylene, linear low-density polyethylene, polypropylene, and α-olefin copolymers (ethylene-propylene copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-butene copolymer (EBR), ethylene-hexene copolymer, ethylene-octene copolymer, ion-bridged olefin copolymers (ionomers), etc.).

[0041] Unsaturated carboxylic acids, their anhydrides, or derivatives are compounds, anhydrides, or derivative groups having an ethylenically unsaturated bond and a carboxyl group in one molecule. Specific examples of unsaturated carboxylic acids include: unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, endo-bicyclo[2.2.1]hept-2,3-dicarboxylic acid (nadic acid), methyl-endo-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, there may be mentioned maleic acid chloride, maleimide, N-phenylmaleimide, maleic anhydride, itaconic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate, etc. Among them, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and itaconic anhydride are preferred, and maleic anhydride is particularly preferred.

[0042] 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).

[0043] A preferred example of the saponified polyolefin resin is a saponified ethylene-vinyl acetate copolymer.

[0044] The modified polyolefin resin used in the present invention complies with JIS K7210 (2014). Furthermore, the modified polyolefin resin used in the present invention preferably has a melt flow index (MFR) measured at 190°C or 230°C under a load of 2.16 kg of 0.1 to 100 g / 10 minutes, more preferably 0.1 to 50 g / 10 minutes. If the melt flow index is less than 0.1 g / 10 minutes, the viscosity becomes too high and the fluidity of the nylon composition is poor, which can deteriorate the moldability of melt extrusion molding, etc. On the other hand, if the melt flow index exceeds 100 g / 10 minutes, the moldability becomes unstable and the mechanical strength and heat resistance of the molded product are reduced.

[0045] Specific examples of the modified polyolefin resins used in the present invention are shown below. Examples of maleic anhydride-modified polyethylene resins and maleic anhydride-modified polypropylene resins include "ADMERNF518 (trade name), ADMER QE800 (trade name)" manufactured by Mitsui Chemicals, Inc. and "Modic (trade name)" manufactured by Mitsubishi Chemical Corporation. Examples of maleic anhydride-modified ethylene-propylene copolymers include "TAFMER MP0610 (trade name), TAFMER MP0620 (trade name)" manufactured by Mitsui Chemicals, Inc. Examples of maleic anhydride-modified ethylene-butene copolymers include "TAFMER MH7010 (trade name), TAFMER MH7020 (trade name)" manufactured by Mitsui Chemicals, Inc. Examples of maleic anhydride-modified styrene-ethylene / butylene-styrene copolymers include "Tuftec (trade name)" manufactured by Asahi Kasei Chemicals Co., Ltd., "SEPTON (trade name)" manufactured by Kuraray Co., Ltd., and "KRATON (trade name)" manufactured by Kraton Polymer Japan Corp. Examples of saponified ethylene-vinyl acetate copolymers include "Technolink (trade name)" manufactured by Taoka Chemical Co., "Mersen (trade name)" manufactured by Toso, "Eval (trade name)" manufactured by Kuraray Co., Ltd., and "Soarnol (trade name)" manufactured by Mitsubishi Chemical Corporation.

[0046] The amount of the modified polyolefin resin blended is 0.5-5% by mass, preferably 1-3% by mass. If the blended amount is less than 0.5% by mass, the load-bearing capacity and sliding characteristics of molded products made from the nylon composition may not be improved. On the other hand, if the blended amount exceeds 5% by mass, the moldability of the nylon composition may deteriorate.

[0047] The phosphate contained in the nylon composition of the present invention is not a substance that exhibits lubricity, as do solid lubricants such as graphite or molybdenum disulfide. However, by incorporating the phosphate into the nylon composition, it promotes the film formation of a lubricating film, such as PTFE, on the surface of the opposing element (sliding surface) during sliding movement relative to the opposing element, and improves the wear resistance of molded products (sliding elements) made from the nylon composition. Furthermore, because molded products of the nylon composition containing the phosphate are less susceptible to the surface roughness of the opposing element, they can be used in applications requiring wear resistance.

[0048] By mixing in a small amount of phosphate, for example 1% by mass, the effect of promoting lubricating film formation begins to appear, and this effect is maintained up to 5% by mass. However, if the amount of phosphate mixed exceeds 5% by mass, the amount of lubricating film formed on the opposing element surface becomes too large, and wear resistance is reduced. Therefore, the amount of phosphate mixed is 1-5% by mass, preferably 1-3% by mass.

[0049] Examples of preferred phosphates include metal salts selected from the group consisting of orthophosphoric acid, pyrophosphoric acid, and metaphosphoric acid, and mixtures thereof. Specifically, orthophosphates (particularly dibasic and tribasic phosphates), pyrophosphates, and metaphosphates of alkali metals and alkaline earth metals are preferred. As alkali metals and alkaline earth metals, lithium, calcium, and magnesium are particularly preferred. Specific examples thereof include tribasic lithium phosphate, tribasic calcium phosphate, calcium hydrogen phosphate or anhydride, magnesium hydrogen phosphate or anhydride, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate, and magnesium metaphosphate.

[0050] In the nylon composition of the present invention, a lubricant and an antioxidant may be added as additional components. In addition, organic particles or organic fibers may be mixed as additional components.

[0051] The lubricant acts as a release agent, which is blended with the nylon composition and improves the demolding properties of the nylon composition during molding. Examples of lubricants include hydrocarbon waxes such as paraffin wax, microcrystalline wax, polyethylene wax and polyethylene oxide wax, sodium salts of higher fatty acids having 12 or more carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, ricinoleic acid and cyclohexane acid, higher fatty acid metal salts (which are metal salts such as magnesium, aluminum, calcium, barium, zinc, etc.), and higher fatty acid amides having 12 or more carbon atoms such as stearic acid amide, oleic acid amide, erucic acid amide, ethylene bisoleic acid amide, ethylene bisstearic acid amide, and methylene bisstearic acid amide. Specifically, from the viewpoint of demolding properties, lubricants having a melting point of 120°C to 155°C are preferred. Examples of such lubricants include ethylene bisstearic acid amide, zinc stearate, polyethylene wax and polyethylene oxide wax.

[0052] The amount of lubricant mixed is 0.1-1% by mass, preferably 0.3-0.5% by mass. If the amount is less than 0.1% by mass, the effect as a release agent is not exhibited. On the other hand, even when the amount exceeds 1% by mass, the release property is not improved.

[0053] Examples of antioxidants as additional components include phenolic antioxidants and phosphite antioxidants. Only one type of antioxidant may be used, or two or more types may be used in combination. In addition to improving the antioxidant performance effect at high temperatures, phenolic antioxidants are excellent in low-temperature antioxidant performance.

[0054] Examples of phenolic antioxidants include 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-butylenetris(3-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 4,4'-thiobis(3-methyl-6-tert-butylphenol), n-octadecyl 3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionate, n-octadecyl 2-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionate, 1,6-Hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylene)propionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5,5 ]-undecane, 2-tert-butyl-6-(3'-tert-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenyl acrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, and N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-dihydrocinnamic acid, N,N'-ethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], N,N'-tetramethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], N,N'-hexamethylenebis[3 -(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], N,N'-ethylenebis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionamide], N,N'-hexamethylenebis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionamide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, N,N'-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionyl]hydrazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate).

[0055] Among them, 4,4′-butylenebis(3-methyl-6-tert-butylphenol), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane are preferably used.

[0056] Specific examples of the phenolic antioxidants include “ADK STAB (trade name)” manufactured by ADEKA Corporation, “SUMILIZER (trade name)” manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, “Irganox (trade name)” manufactured by BASF SE, “KEMINOX (trade name)” manufactured by Chemipro Kasei Kaisha, Ltd., and “Tominox (trade name)” manufactured by YOSHITOMI PHARMACEUTICAL INDUSTRIES, LTD.

[0057] In addition, examples of the phosphite-based antioxidants include triphenylphosphine, tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, tri(octadecyl) phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, distearyl pentaerythritol diphosphate, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, 2,2-methylenebis(4,6-di-tert-butylphenyl) octyl phosphite, bis(nonylphenyl) pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, distearyl-pentaerythritol-diphosphite and the like.

[0058] Among them, tris(nonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite are preferably used.

[0059] Specific examples of the phosphite-based antioxidants include “Irgafos (trade name)” manufactured by BASF SE, “ADK STAB (trade name)” manufactured by ADEKA Corporation, “JP (trade name)” manufactured by Johoku Chemical Co., Ltd., “JPP (trade name)” manufactured by Johoku Chemical Co., Ltd., and “GSY (trade name)” manufactured by Osaki Industry Co., Ltd.

[0060] The blending amount of the antioxidant is 0.1-2% by mass, preferably 0.2-1.5% by mass. If the blending amount is less than 0.1% by mass, the antioxidant effect is not exhibited. On the other hand, even if the blending amount exceeds 2% by mass, the antioxidant performance cannot be improved.

[0061] Examples of the organic particles and organic fibers as additional components include meta-aramid particles, para-aramid particles, meta-aramid fibers, para-aramid fibers, PBO (poly-p-phenylene benzobisoxazole) fibers, polyarylate fibers, novoloid fibers, etc. The organic particles and organic fibers significantly improve sliding properties (including low friction and wear resistance) without reducing the mechanical strength of molded products (sliding elements) made of the nylon composition.

[0062] Specific examples of meta-aramid particles include "Conex powder (trade name)" manufactured by TEIJIN LIMITED. Specific examples of para-aramid particles include "Twaron (registered trademark) 5011 (trade name)" manufactured by TEIJIN LIMITED. Specific examples of meta-aramid fibers include "Conex staplefiber (trade name)" manufactured by TEIJIN LIMITED. Specific examples of para-aramid fibers include "Twaron (registered trademark) 1088 (trade name)" manufactured by TEIJIN LIMITED. Specific examples of PBO fibers include "ZYLOM-AS (trade name)" manufactured by TOYOBO CO., LTD. Specific examples of polyarylate fibers include "Vectran HT (trade name)" manufactured by Kuraray Co., Ltd., and specific examples of novoloid fibers include "Kynol KF-10BT (trade name)" manufactured by Gun Ei Chemical Industry Co., Ltd.

[0063] The amount of organic particles or organic fibers blended is 1-40% by mass, preferably 1-30% by mass, and more preferably 3-15% by mass. If the blended amount is less than 1% by mass, the effects of improving moldability, wear resistance, and sliding properties are not exhibited. On the other hand, if the blended amount exceeds 40% by mass, there is a risk that the moldability of the resin composition for sliding elements may deteriorate, and the mechanical strength of molded products made from the nylon composition may deteriorate.

[0064] The nylon composition of the present invention can be easily prepared using known methods commonly used to prepare conventional resin compositions. For example, nylon, polyethylene resin, PTFE, modified polyolefin resin, and phosphate, or other lubricants and antioxidants, and organic particles or fibers are weighed to a predetermined amount. These are then mixed using a mixer such as a Henschel mixer, super mixer, ball mill, or drum mixer to prepare a mixture. The mixture is then fed into a single-shaft or twin-shaft screw extruder and melt-kneaded to form a strand-shaped molded product (strand). This strand-shaped molded product is then cut to prepare pellets as a molding material. For another example, polyethylene resin, PTFE, modified polyolefin resin, and phosphate, or other lubricants and antioxidants, and organic particles or fibers are weighed to a predetermined amount. These are then mixed using the same mixer as above to prepare a mixture. The mixture is then fed into a single-shaft or twin-shaft screw extruder and melt-kneaded to form a strand-shaped molded product. Thereafter, the strand-shaped molded product is cut to prepare pellets, which are then mixed with nylon at a predetermined ratio to be used as a molding material.

[0065] The nylon composition of the present invention exhibits good bite into a molding machine screw and excellent molding processability. Furthermore, the surface of the molded product exhibits excellent surface condition due to the absence of peeling. Furthermore, sliding elements manufactured from this nylon composition exhibit significantly improved sliding characteristics, including low frictional resistance and wear resistance, without impairing the initial mechanical properties of nylon. Furthermore, sliding friction between opposing elements can be significantly improved.

[0066] Example

[0067] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, as long as the scope of the present invention is not exceeded. The moldability of the nylon composition and the friction and wear characteristics of the sliding element manufactured from the nylon composition were evaluated by the following methods.

[0068] <Moldability (1)>

[0069] In the case where the mixture (nylon composition) was melt-kneaded using an extruder to form a rope-shaped molded product and then cut to produce pellets, the presence or absence of cracks (cuts) in the rope-shaped molded product, the bite property into the screw, and the surface condition of the pellets (occurrence of voids (bubbles), etc.) were visually observed. Evaluation was performed according to the evaluation criteria in Table 1.

[0070] Table 1

[0071] ◎…Excellent

[0072] ○…Good

[0073] ×…Impossible

[0074] <Moldability (2)>

[0075] In the case where a molded product (sliding element) was molded from the pellets using an injection molding machine, the releasability of the molded product and the surface condition (peeling, etc.) of the molded product were visually observed. Evaluation was performed according to the evaluation criteria in Table 2.

[0076] Table 2

[0077] ◎…Excellent

[0078] ○…Good

[0079] ×…Impossible

[0080] <Friction and Wear Characteristics>

[0081] The friction coefficient and wear volume were measured using a puncture tester under the conditions shown in Table 3. Figure 1 As shown, a square bearing test piece (sliding element) 1 with a side length of 30 mm and a thickness of 3 mm is fixed to the test bench. Then, when a predetermined load is applied to one surface 3 of the bearing test piece 1 from a cylinder 2 as an opposing element in a direction X perpendicular to the surface 3, the cylinder 2 rotates around the axis 4 of the cylinder 2 in the direction Y. And the friction coefficient between the bearing test piece 1 and the cylinder 2 and the amount of wear on the surface 3 of the bearing test piece 1 after the test are measured. The friction coefficient is shown by the friction coefficient of the stability time from 1 hour after the start of the test to the end of the test. The wear amount is shown by the amount of dimensional change of the sliding surface after the test time of 8 hours.

[0082] Table 3

[0083] <Jab Test>

[0084] Sliding speed 10m / min

[0085] Load (surface pressure) 100kgf / cm 2

[0086] Test time 8h

[0087] Test piece square sliding element (3mm side length, 1mm thickness)

[0088] Opposing element Hollow cylindrical opposing element [Carbon steel (S45C) for machine structure,

[0089] Inner diameter 20mm, outer diameter 25.6mm, length 15mm]

[0090] Lubrication No lubrication

[0091] In the following examples, the following materials were used as nylon, polyethylene resin, PTFE, modified polyolefin resin, phosphate, lubricant, antioxidant, organic particles, and organic fiber. The following materials all represent trade names.

[0092] [A] Nylon

[0093] (A-1) Nylon 6

[0094] Nylon 6A1030JR, manufactured by UNITIKA LTD.

[0095] (A-2) Nylon 66

[0096] "Ultramid A", manufactured by BASF SE.

[0097] (A-3) Nylon 12

[0098] "DIAMID X1988", manufactured by Daicel-Evonik Corporation Ltd.

[0099] (A-4) Nylon 46

[0100] "Stanyl", manufactured by DSM Japan KK.

[0101] (A-5) Nylon 9T

[0102] "Genestar", manufactured by Kuraray Co., Ltd.

[0103] (A-6) Nylon 10T

[0104] "XecoT" (biomass content 56.4%), manufactured by UNITIKA LTD.

[0105] (A-7) Nylon 11

[0106] "Rilsan" (biomass content 100%), manufactured by ARKEMA KK.

[0107] (A-8) Nylon 610

[0108] "VESTAMID HS16" (biomass degree 60%), manufactured by Daicel-Evonik Corporation Ltd.

[0109] (A-9) Nylon 1010

[0110] "VESTAMID DS12 (biomass degree 100%)", manufactured by Daicel-Evonik Corporation Ltd.

[0111] [B] Polyethylene resin

[0112] (B-1) High-density polyethylene resin

[0113] "HI-ZEX", manufactured by Prime Polymer Co., Ltd.

[0114] (B-2) Ultra-high molecular weight polyethylene resin

[0115] "MIPELON", manufactured by Mitsui Chemicals, Inc.

[0116] (B-3) Maleic anhydride acid-modified ultra-high molecular weight polyethylene resin

[0117] "Modified LUBMER" manufactured by Mitsui Chemicals, Inc.

[0118] (B-4) Plant-derived polyethylene resin

[0119] "Green polyethylene" (biomass content 94.5%), manufactured by Braskem SA.

[0120] [C]PTFE

[0121] "KT300M", manufactured by KITAMURA LIMITED.

[0122] [D] Modified polyolefin resin

[0123] (D-1) Saponified ethylene-vinyl acetate copolymer

[0124] “Technolink K431-80” manufactured by Taoka Chemical Co., Ltd. (vinyl acetate content before saponification: 28% by mass, saponification degree: 80%, MFR: 4 g / 10 min: 190° C., load: 2.16 kg).

[0125] (D-2) Saponified ethylene-vinyl acetate copolymer

[0126] "MELTHENE H-6051" manufactured by Tosoh Corporation (vinyl acetate content before saponification: 28% by mass, saponification degree: 100%, MFR: 5.5 g / 10 min: 190°C, load: 2.16 kg).

[0127] (D-3) Maleic anhydride-modified polyethylene resin

[0128] “ADMER-NF518” manufactured by Mitsui Chemicals, Inc. (MFR 2.2 g / 10 min: 230° C., load 2.16 kg).

[0129] (D-4) Maleic anhydride-modified ethylene-propylene copolymer

[0130] “TAFMER-MP 0620”, manufactured by Mitsui Chemicals, Inc. (MFR 0.3 g / 10 min: 230° C., load 2.16 kg).

[0131] (D-5) Maleic anhydride-modified ethylene-butene copolymer

[0132] "TAFMER-MH 7020", manufactured by Mitsui Chemicals, Inc. (MFR 1.5 g / 10 min: 230°C, load 2.16 kg).

[0133] (D-6) Maleic anhydride modified styrene-ethylene / butylene-styrene copolymer

[0134] "Tuftec H1517", manufactured by Asahi Kasei Chemicals Co., Ltd. (MFR 3.0 g / 10 min: 230°C, load 2.16 kg).

[0135] [E] Phosphate

[0136] (E-1) Calcium pyrophosphate (manufactured by YONEYAMA KAGAKU KOGYO KAISHA, LTD.)

[0137] (E-2) Magnesium metaphosphate (manufactured by Taihei Chemical Industrial Co., Ltd.)

[0138] [F] Lubricant

[0139] (F-1) Ethylene bisstearamide

[0140] "Kaowax" (melting point 143°C), manufactured by Kao Corporation.

[0141] (F-2) Zinc stearate

[0142] "Zinc stearate" (melting point 140°C), manufactured by NITTO KASEI KOGYO KK.

[0143] (F-3) Polyethylene oxide wax

[0144] "LICOWAX PED 191" (melting point 123°C), manufactured by Clariant Plastics & Coatings (Japan) KK.

[0145] [G] Antioxidants

[0146] (G-1) Phenolic antioxidant, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane

[0147] "ADK STAB AO-80", manufactured by ADEKA Corporation.

[0148] (G-2) Phosphite antioxidant, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite

[0149] "ADK STAB PEP-36", manufactured by ADEKA Corporation.

[0150] [H] Organic particles and organic fibers

[0151] (H-1) Meta-aramid particles

[0152] "Conex powder", manufactured by TEIJIN LIMITED.

[0153] (H-2) para-aramid particles

[0154] "Twaron (registered trademark) 5011", manufactured by TEIJIN LIMITED.

[0155] (H-3) meta-aramid fiber

[0156] "Conex staple fiber," manufactured by TEIJIN LIMITED.

[0157] (H-4) para-aramid fiber

[0158] "Twaron (registered trademark) 1088", manufactured by TEIJIN LIMITED.

[0159] (H-5)PBO fiber

[0160] "ZYLOM-AS", manufactured by TOYOBO CO., LTD.

[0161] (H-6) Polyarylate Fiber

[0162] "Vectran HT", manufactured by Kuraray Co., Ltd.

[0163] (H-7) Novoid fiber

[0164] "Kynol KF-10BT", manufactured by Gun Ei Chemical Industry Co., Ltd.

[0165] Examples 1-15

[0166] Aliphatic nylons (A-1) to (A-4) and semiaromatic nylon (A-5) as the main nylon components, and polyethylene resins (B-1) to (B-3), PTFE (C), modified polyolefin resins (D-1) to (D-6), phosphates (E-1) and (E-2), lubricants (F-1) to (F-3), and antioxidants (G-1) and (G-2) as additives were prepared and weighed in the ratios shown in Tables 4-6. These were then mixed using a drum mixer to prepare a mixture. This mixture was then fed to a twin-screw extruder and melt-kneaded to form a strand-shaped molded product. Thereafter, this strand-shaped molded product was cut to prepare pellets, which were used as molding materials. During the production process, the strand-shaped molded product was visually inspected for the presence or absence of cracks (cuts), its ability to bite into the screw, and the surface condition of the pellets (such as the presence of voids). These evaluations are shown as properties (moldability 1) in Tables 4-6.

[0167] Next, the molding material was supplied to a screw type injection molding machine and injection molded to produce a square type molded product (sliding element) having a size of 30 mm in length and 3 mm in thickness. In the manufacturing method, the demoulding properties of the square type molded product from the mold and the surface condition (peeling, etc.) of the square type molded product were visually observed. These evaluations are shown in the characteristics (molding properties 2) of Table 4-6. In addition, the friction coefficient and wear amount of the square type molded product were evaluated based on the above evaluation method. The results are shown in the characteristics (sliding properties) of Table 4-6.

[0168] Examples 16-26

[0169] Nylon and plant-derived nylons (A-6) to (A-9) as main components, and polyethylene resins (B-2) to (B-4), PTFE (C), modified polyolefin resins (D-2) to (D-6), phosphates (E-1) and (E-2), lubricants (F-1) to (F-3), and antioxidants (G-1) and (G-2) as additives were prepared and weighed in the ratios shown in Tables 7-8. These were then mixed using a drum mixer to prepare a mixture. This mixture was then fed to a twin-screw extruder and melt-kneaded to form a strand-shaped molded product. Thereafter, this strand-shaped molded product was cut to prepare pellets, which were used as molding materials. During the production process, the strand-shaped molded product was visually inspected for the presence or absence of cracks (cuts), its ability to bite into the screw, and the surface condition of the pellets (such as the presence of voids). These evaluations are shown as properties (moldability 1) in Tables 7-8.

[0170] Next, the molding material was supplied to a screw type injection molding machine and injection molded to produce a square type molded product (sliding element) having a size of 30 mm in length and 3 mm in thickness. In the manufacturing method, the demoulding properties of the square type molded product from the mold and the surface condition (peeling, etc.) of the square type molded product were visually observed. These evaluations are shown in the characteristics (molding properties 2) of Table 7-8. In addition, the friction coefficient and wear amount of the square type molded product were evaluated based on the above evaluation method. The results are shown in the characteristics (sliding properties) of Table 7-8.

[0171] Examples 27-48

[0172] Nylon, a plant-derived nylon (A-6) as the main component, and polyethylene resins (B-3) and (B-4), PTFE (C), a modified polyolefin resin (D-2), a phosphate (E-2), a lubricant (F-3), antioxidants (G-1) and (G-2), and organic particles or fibers (H-1) to (H-7) as additives were prepared and weighed in the ratios shown in Tables 9-11. These were then mixed using a drum mixer to prepare a mixture. This mixture was then fed into a twin-screw extruder and melt-kneaded to form a strand-shaped molded product. This strand-shaped molded product was then cut to prepare pellets, which were used as molding materials. During the production process, the presence or absence of cracks (cuts) in the strand-shaped molded product, its ability to bite into the screw, and the surface condition of the pellets (such as the generation of voids) were visually observed. These evaluations are shown in the properties (Moldability 1) in Tables 9-11.

[0173] Next, the molding material was supplied to a screw-type injection molding machine and injection molded to produce a square-type molded product (sliding element) having a size of 30 mm in length and 3 mm in thickness. During the manufacturing process, the demoulding properties of the square-type molded product from the mold and the surface condition (peeling, etc.) of the square-type molded product were visually observed. These evaluations are shown in the properties (molding properties 2) of Tables 9-11. Furthermore, the friction coefficient and wear amount of the square-type molded product were evaluated based on the above-mentioned evaluation method. The results are shown in the properties (sliding properties) of Tables 9-11.

[0174] Comparative Examples 1-8

[0175] Nylon as a main component, the same as in the above examples (A-1), (A-2), (A-4), (A-5) and (A-6), and as additives, the same as in the above examples, polyethylene resins (B-1) to (B-4), PTFE (C), modified polyolefin resin (D-2), phosphate (E-2), lubricant (F-3), antioxidants (G-1) and (G-2), and meta-aramid particles (H-1), and further, molybdenum disulfide ("NICHIMOLY molybdenum disulfide powder", manufactured by Daizo Corporation), glass fiber ("03JAFT692", manufactured by Asahi Fiber Glass Co., Ltd.), potassium titanate whiskers ("Tismo (trade name)", manufactured by Otsuka Chemical Co., Ltd.), and mica were prepared and weighed in the ratios of the amounts shown in Table 12. Next, they were mixed with a drum mixer to prepare a mixture. The mixture was then fed to a twin-screw extruder and melt-kneaded to form a rope-shaped molded product. The rope-shaped molded product was then cut to produce pellets, which were used as molding materials. During the production process, the rope-shaped molded product was visually observed for the presence or absence of cracks (cuts), its ability to bite into the screws, and the surface condition of the pellets (such as the presence of voids). These evaluations are shown in the properties in Table 12.

[0176] Next, the molding material was supplied to a screw type injection molding machine and injection molded to produce a square type molded product (sliding element) having a size of 30 mm in length and 3 mm in thickness. In the manufacturing method, the demoulding property of the square type molded product from the mold and the surface condition (peeling, etc.) of the square type molded product were visually observed. These evaluations are shown in the characteristics of Table 12. In addition, the friction coefficient and wear amount of the square type molded product were evaluated based on the above evaluation method. The results are shown in the characteristics of Table 12.

[0177] Table 4

[0178]

[0179]

[0180] Table 5

[0181]

[0182]

[0183] Table 6

[0184]

[0185]

[0186] Table 7

[0187]

[0188]

[0189]

[0190] Table 8

[0191]

[0192]

[0193] Table 9

[0194]

[0195]

[0196] Table 10

[0197]

[0198]

[0199]

[0200] Table 11

[0201]

[0202]

[0203] Table 12

[0204]

[0205]

[0206] The above test results show that Examples 1-48 of the nylon compositions exhibited good screw penetration during extrusion. Furthermore, no cracking (cutting) of the rope-shaped molded products was observed during the molding process of the rope-shaped molded products. Furthermore, it was confirmed that the molding material (pellet) formed from the rope-shaped molded products exhibited good penetration into the molding machine screw and excellent molding processability. Furthermore, it was confirmed that the surface of the molded products exhibited no peeling and had excellent surface conditions. Meanwhile, Comparative Examples 1-6 of the nylon compositions exhibited no particular problems with moldability. However, Comparative Examples 7 and 8 of the nylon compositions exhibited cracking (cutting) in the rope-shaped molded products during extrusion, and a good rope-shaped molded product could not be obtained. Therefore, in Comparative Examples 7 and 8, no injection molding machine was used for evaluation (Moldability 2).

[0207] Furthermore, all the molded products (sliding elements) of Examples 1 to 48 made from nylon compositions exhibited low coefficients of friction and small amounts of wear. On the other hand, the molded products (sliding elements) of Comparative Examples 1 and 4 made from nylon compositions exhibited high coefficients of friction and very large amounts of wear. Testing of the molded products (sliding elements) of Comparative Examples 2, 3, 5, and 6 of nylon compositions was stopped due to an increase in the coefficient of friction during testing. In the case of Comparative Examples 7 and 8 of nylon compositions, friction and wear characteristics were not tested because good molded materials could not be obtained. From the above, it can be seen that the molded products (sliding elements) made from the nylon compositions of the Examples have excellent sliding characteristics compared to the molded products (sliding elements) made from the nylon compositions of the Comparative Examples.

[0208] As described above, the nylon composition and sliding element of the present invention exhibit good screw-biting properties and excellent molding processability. Furthermore, the molded product exhibits no surface peeling and excellent surface conditions. Furthermore, sliding elements made from the nylon composition exhibit significantly improved sliding characteristics (including low friction and wear resistance) during sliding friction between opposing elements without impairing the initial mechanical properties of the nylon. Therefore, the present invention provides such a nylon composition and sliding element.

[0209] Reference Signs List

[0210] 1 Bearing test piece (sliding element)

[0211] 2 cylinders (opposite components)

[0212] 4-axis

Claims

1. A polyamide resin composition for a sliding element, which contains the following as an additive in addition to the main component polyamide resin: 5-20% by mass of a polyethylene resin, wherein the polyethylene resin is selected from a high-density polyethylene resin, an ultra-high molecular weight polyethylene resin, and an acid-modified ultra-high molecular weight polyethylene resin; Polytetrafluoroethylene resin 5-30% by mass; Modified polyolefin resin 0.5-5% by mass; and Phosphate 1-5% by mass.

2. The polyamide resin composition for a sliding element according to claim 1, wherein: The polyamide resin is selected from aliphatic polyamide resins, semi-aromatic polyamide resins and plant-derived polyamide resins.

3. The polyamide resin composition for a sliding element according to claim 1, wherein: The polytetrafluoroethylene resin is used as a lubricant additive.

4. The polyamide resin composition for a sliding element according to claim 2, wherein: The polytetrafluoroethylene resin is used as a lubricant additive.

5. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein: The modified polyolefin resin is selected from polyolefin resins graft-modified with unsaturated carboxylic acids, derivatives thereof, and saponified polyolefin resins obtained by saponifying a polyolefin resin having an acetoxy group in its molecular chain with an alkali.

6. The polyamide resin composition for sliding elements according to claim 5, wherein: The polyolefin resin graft-modified with unsaturated carboxylic acid or its derivative is selected from maleic anhydride-modified polyethylene resin, maleic anhydride-modified polypropylene resin, maleic anhydride-modified ethylene-α-olefin copolymer and maleic anhydride-modified styrene-ethylene / butylene-styrene copolymer.

7. The polyamide resin composition for a sliding element according to claim 5, wherein: The saponified polyolefin resin consists of a saponified ethylene-vinyl acetate copolymer.

8. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein: The phosphate is selected from the group consisting of orthophosphates, pyrophosphates and metaphosphates of alkali metals or alkaline earth metals.

9. The polyamide resin composition for a sliding element according to claim 5, wherein: The phosphate is selected from the group consisting of orthophosphates, pyrophosphates and metaphosphates of alkali metals or alkaline earth metals.

10. The polyamide resin composition for a sliding element according to claim 6, wherein: The phosphate is selected from the group consisting of orthophosphates, pyrophosphates and metaphosphates of alkali metals or alkaline earth metals.

11. The polyamide resin composition for a sliding element according to claim 7, wherein: The phosphate is selected from the group consisting of orthophosphates, pyrophosphates and metaphosphates of alkali metals or alkaline earth metals.

12. The polyamide resin composition for a sliding element according to claim 8, wherein: The phosphate is selected from the group consisting of tri-generation lithium phosphate, tri-generation calcium phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate and magnesium metaphosphate.

13. The polyamide resin composition for a sliding element according to claim 9, wherein: The phosphate is selected from the group consisting of tri-generation lithium phosphate, tri-generation calcium phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate and magnesium metaphosphate.

14. The polyamide resin composition for a sliding element according to claim 10, wherein: The phosphate is selected from the group consisting of tri-generation lithium phosphate, tri-generation calcium phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate and magnesium metaphosphate.

15. The polyamide resin composition for a sliding element according to claim 11, wherein: The phosphate is selected from the group consisting of tri-generation lithium phosphate, tri-generation calcium phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate and magnesium metaphosphate.

16. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

17. The polyamide resin composition for a sliding element according to claim 5, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

18. The polyamide resin composition for a sliding element according to claim 6, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

19. The polyamide resin composition for a sliding element according to claim 7, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

20. The polyamide resin composition for a sliding element according to claim 8, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

21. The polyamide resin composition for a sliding element according to claim 12, wherein: As additives, organic particles or organic fibers are mixed in a ratio of 1 to 40% by mass.

22. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

23. The polyamide resin composition for a sliding element according to claim 5, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

24. The polyamide resin composition for a sliding element according to claim 6, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

25. The polyamide resin composition for a sliding element according to claim 7, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

26. The polyamide resin composition for a sliding element according to claim 8, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

27. The polyamide resin composition for a sliding element according to claim 12, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

28. The polyamide resin composition for a sliding element according to claim 16, wherein: As an additive, a lubricant selected from hydrocarbon waxes, higher fatty acid metal salts and higher fatty acid amides is mixed at a ratio of 0.1 to 1% by mass.

29. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

30. The polyamide resin composition for a sliding element according to claim 5, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

31. The polyamide resin composition for a sliding element according to claim 6, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

32. The polyamide resin composition for a sliding element according to claim 7, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

33. The polyamide resin composition for a sliding element according to claim 8, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

34. The polyamide resin composition for a sliding element according to claim 12, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

35. The polyamide resin composition for a sliding element according to claim 16, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

36. The polyamide resin composition for a sliding element according to claim 22, wherein: As an additive, an antioxidant consisting of a phenolic antioxidant and / or a phosphite antioxidant is mixed at a ratio of 0.1 to 2% by mass.

37. The polyamide resin composition for a sliding element according to any one of claims 1 to 4, wherein the modified polyolefin resin has an acid group that interacts with the polyamide resin and acts as a compatibilizer for dispersing the polyolefin resin in the polyamide resin matrix.

38. The polyamide resin composition for a sliding member according to claim 5, wherein the derivative comprises an acid anhydride.

39. A sliding element made of the polyamide resin composition for a sliding element according to any one of claims 1 to 4.

40. A sliding element made of the polyamide resin composition for a sliding element according to claim 5.

41. A sliding element made of the polyamide resin composition for a sliding element according to claim 6.

42. A sliding element made of the polyamide resin composition for a sliding element according to claim 7.

43. A sliding element made of the polyamide resin composition for a sliding element according to claim 8.

44. A sliding element made of the polyamide resin composition for a sliding element according to claim 12.

45. A sliding element made of the polyamide resin composition for a sliding element according to claim 16.

46. ​​A sliding element made of the polyamide resin composition for a sliding element according to claim 22.

47. A sliding element made of the polyamide resin composition for a sliding element according to claim 29.

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