Resin composition for sliding parts and sliding parts

Abstract

The present invention provides a resin composition for sliding parts, which contains, in addition to 40 to 80% by mass of a polyphenylene sulfide resin, 15 to 40% by mass of a tetrafluoroethylene resin, 2 to 20% by mass of an ultrahigh molecular weight polyethylene resin, 0.1 to 5% by mass of a modified polyolefin resin, and 0.5 to 5% by mass of an amorphous polymer as additives.

Description

[Technical field]

[0001] The present invention relates to a resin composition for a sliding part and a sliding part. [Background Technology]

[0002] Polyphenylene sulfide resin has excellent heat resistance, chemical resistance and formability, etc., so it is used as a sliding part of OA equipment, household appliances, etc. In addition, it is expected to be used as a sliding part for food machinery that is subjected to heat sterilization and hypochlorous acid sterilization. Generally speaking, polyphenylene sulfide resin itself has a small elongation and poor toughness. In addition, the self-lubricating property is also insufficient. Therefore, when used as a sliding part, in addition to the reinforcement performed by inorganic fibers such as glass fibers, solid lubricants are usually added to use it. For example, in patent document 1, a bearing body formed by a composition containing glass fibers or carbon fibers and tetrafluoroethylene resin in polyphenylene sulfide resin is proposed. However, in the case of using soft metals such as stainless steel and aluminum alloy as a mating part, the sliding part formed by adding reinforcing filling materials such as glass fibers and carbon fibers has the following problems: the mating part will be damaged during sliding with the mating part, and abrasive wear will develop.

[0003] In order to compensate for the drawback of damaging the sliding partner, a sliding component composed of a resin composition in which a phosphate is blended in addition to a reinforcing filler such as glass fiber and carbon fiber and a tetrafluoroethylene resin in a polyphenylene sulfide resin is proposed in Patent Document 2. This sliding component prevents the reinforcing filler from damaging the partner by utilizing the film-forming property of the phosphate on the lubricating film of the partner, and improves the lubricity. However, under severe use conditions such as high loads, there is a problem that both the wear resistance and lubricity are insufficient.

[0004] In addition, Patent Document 3 proposes a sliding part that does not use reinforcing fillers such as glass fiber and carbon fiber as described above, but instead mixes unsintered high molecular weight tetrafluoroethylene resin, kneads and fibrosis the high molecular weight tetrafluoroethylene resin to orient it, thereby achieving an improvement in the mechanical strength of the molded product and imparting wear resistance and lubricity. However, in order to impart sufficient toughness, wear resistance, and lubricity, a large amount of high molecular weight tetrafluoroethylene resin needs to be mixed. In this case, there is the following problem: the fibrous high molecular weight tetrafluoroethylene resin is easy to agglomerate, and the agglomerate causes the poor appearance of the molded product and the rough surface during mechanical processing. Furthermore, polyphenylene sulfide resin has poor toughness and is relatively brittle as described above, and there is a problem of abnormal wear when the surface roughness of the sliding mating part is large.

[0005] [Prior art literature]

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 55-227

[0008] Patent Document 2: Japanese Patent No. 2954638

[0009] Patent Document 3: Japanese Patent No. 2790692 [Summary of the invention]

[0010] Problems to be solved by the invention

[0011] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a resin composition for sliding parts and a sliding part which are excellent in moldability and machinability and can improve sliding characteristics and mechanical properties including lubricity and wear resistance.

[0012] Means for solving problems

[0013] The resin composition for sliding parts of the present invention comprises 15 to 40% by mass of a tetrafluoroethylene resin, 2 to 20% by mass of an ultrahigh molecular weight polyethylene resin, 0.1 to 5% by mass of a modified polyolefin resin and 0.5 to 5% by mass of an amorphous polymer as additives, relative to 40 to 80% by mass of a polyphenylene sulfide resin.

[0014] The resin composition for a sliding member of the present invention may contain 0.1 to 10% by mass of at least one selected from phosphates, carbonates and sulfates as an additional component.

[0015] Effects of the Invention

[0016] According to the present invention, a resin composition for sliding parts and a sliding part capable of improving sliding properties including lubricity and wear resistance can be provided. [Specific implementation method]

[0017] Hereinafter, the details of the present invention will be described.

[0018] The resin composition for sliding parts of the present invention comprises 15 to 40% by mass of a tetrafluoroethylene resin, 2 to 20% by mass of an ultrahigh molecular weight polyethylene resin, 0.1 to 5% by mass of a modified polyolefin resin and 0.5 to 5% by mass of an amorphous polymer as additives, relative to 40 to 80% by mass of a polyphenylene sulfide resin.

[0019] The polyphenylene sulfide resin constitutes the base material of the resin composition for sliding parts of the present invention, and there are cross-linked type, linear type, and semi-linear type with different molecular structures. In the present invention, there is no particular limitation, but from the perspective of suppressing poor molding such as insufficient filling, carbonization, and discoloration inside the mold caused by outgassing, the semi-linear type is preferred. For example, the cross-linked type can be "T4 (trade name)" manufactured by DIC Corporation, the linear type can be "W-214 (trade name)" manufactured by Polyplastics Co., Ltd., and the semi-linear type can be "Ecotran N-200 (trade name)" manufactured by Teijin Co., Ltd.

[0020] The content of the polyphenylene sulfide resin needs to be 40 to 80% by mass, preferably 49 to 69% by mass, thereby maintaining the inherent excellent heat resistance, chemical resistance, moldability, etc. of the polyphenylene sulfide resin.

[0021] The tetrafluoroethylene resin mixed in the sliding part resin composition of the present invention imparts lubricity to the sliding part obtained by molding the sliding part resin composition, and contributes to low friction. The mixing amount is 15 to 40% by mass, preferably 20 to 35% by mass. When the mixing amount is less than 15% by mass, sufficient low friction cannot be obtained, and when the mixing amount exceeds 40% by mass, it becomes a cause of poor appearance caused by the aggregation of the tetrafluoroethylene resin.

[0022] Among tetrafluoroethylene resins, there are high molecular weight tetrafluoroethylene resins mainly used for molding and low molecular weight tetrafluoroethylene resins mainly used for imparting lubricity. In the present invention, either high molecular weight tetrafluoroethylene resin or low molecular weight tetrafluoroethylene resin may be used alone, but it is preferred to mix the high molecular weight tetrafluoroethylene resin and the low molecular weight tetrafluoroethylene resin in an appropriate ratio.

[0023] High molecular weight tetrafluoroethylene resins generally have a molecular weight of several million to ten million, and are mainly used for molding as molding powders or fine powders, and examples thereof include "Polyflon M-12 (trade name)" and "Polyflon M-112 (trade name)" manufactured by Daikin Industries, Ltd. Although not molding powders or fine powders, materials obtained by molding, sintering, and then crushing high molecular weight tetrafluoroethylene resins may also be used. For example, "KT300M (trade name)" manufactured by Kitamura Corporation may be mentioned.

[0024] High molecular weight tetrafluoroethylene resin also helps to impart lubricity, but mainly fibrosis during melt kneading helps to improve the toughness of the sliding parts obtained by molding the sliding parts resin composition and improves the mechanical strength. The amount of high molecular weight tetrafluoroethylene resin is 1 to 10% by mass, preferably 1 to 5% by mass. When the amount is less than 1% by mass, there is no effect of improving the mechanical strength. When the amount exceeds 10% by mass, it is possible to damage the moldability of the sliding parts resin composition and the appearance of the molded product (sliding parts) due to coagulation and excessive viscosity increase.

[0025] Low molecular weight tetrafluoroethylene resin mainly plays the role of imparting lubricity, for example, "Dyneon TF (trade name)" manufactured by 3M, "Lubron L-5 (trade name)" manufactured by Daikin Industries, Ltd., "Fluon L169J (trade name)" manufactured by AGC, etc. can be cited. The blending amount of low molecular weight tetrafluoroethylene resin is 10 to 35% by mass, preferably 15 to 30% by mass. When the blending amount is less than 10% by mass, the imparting of lubricity to the sliding part is insufficient, and when the blending amount exceeds 35% by mass, it becomes a cause of deterioration of the moldability of the resin composition for sliding parts and reduction of the mechanical strength of the molded product (sliding part).

[0026] The ultra-high molecular weight polyethylene resin to be blended in the resin composition for sliding parts of the present invention may have an intrinsic viscosity [η] of 10 dl / g or more measured in a decalinic acid solvent at 135°C and a viscosity average molecular weight of 500,000 to 6,000,000, and examples thereof include "Mipelon (trade name)" manufactured by Mitsui Chemicals, Inc. In addition, as the ultra-high molecular weight polyethylene resin, an ultra-high molecular weight polyethylene resin having an intrinsic viscosity of 10 to 40 dl / g at 135°C and a low molecular weight polyethylene resin or even a high molecular weight polyethylene resin having such an intrinsic viscosity of 0.1 to 5 dl / g may be used, and examples thereof include "Lubmer (trade name)" manufactured by Mitsui Chemicals, Inc. Furthermore, an acid-modified ultra-high molecular weight polyethylene resin may be used, and examples thereof include "Modified Lubmer (trade name)" manufactured by Mitsui Chemicals, Inc. modified with maleic anhydride.

[0027] Ultra-high molecular weight polyethylene resin has the effect of improving the sliding characteristics in the light load, medium speed to high speed range by being added to the resin composition for sliding parts. Generally, it is difficult to improve the sliding characteristics under the above conditions by only using tetrafluoroethylene resin. The amount of ultra-high molecular weight polyethylene resin is 2 to 20% by mass, preferably 2 to 10% by mass. When the amount of ultra-high molecular weight polyethylene resin is less than 2% by mass, the effect of improving the sliding characteristics is lacking. When the amount exceeds 20% by mass, the dispersion ratio to polyphenylene sulfide resin increases, which may deteriorate the wear resistance and moldability.

[0028] As the modified polyolefin resin to be blended in the resin composition for sliding parts of the present invention, there can be used ethylene-based ionomers, polyolefin resins having epoxy groups in the molecule, and polyolefin resins graft-modified with unsaturated carboxylic acids, their anhydrides, or their derivatives.

[0029] Ethylene ionomers are ionic copolymers obtained by adding metal ions with an atomic valence of 1 to 3 to a copolymer of an α-olefin containing ethylene and an α, β-unsaturated carboxylic acid, and have an intermolecular crosslinking structure based on the metal ions. Here, examples of α, β-unsaturated carboxylic acids include acrylic acid, methacrylic acid, and itaconic acid. In addition, representative examples of metal ions with an atomic valence of 1 to 3 include Na + , K + , Ca 2+ 、Zn 2+ 、Al 3+ For example, the intermolecular separation of ethylene-methacrylic acid copolymer with Na + 、Zn 2+ Cross-linked "Himilan (trade name)" manufactured by Mitsui Dow Polychemicals Co., Ltd., etc.

[0030] Specific examples of the polyolefin resin having an epoxy group in the molecule include "BONDFAST (trade name)" manufactured by Sumitomo Chemical Co., Ltd., which is a copolymer of ethylene and glycidyl methacrylate and in which vinyl acetate or methyl acrylate is further copolymerized as a third component, and "MODIPERA 4000 series (trade name)" manufactured by NOF Corporation, which is a copolymer of ethylene and glycidyl methacrylate grafted with polystyrene, polymethyl methacrylate or acrylonitrile-styrene copolymer.

[0031] As the polyolefin resin constituting the main chain of the polyolefin resin obtained by grafting and modifying with unsaturated carboxylic acid, its anhydride or their derivatives, homopolymers of α-olefins, copolymers of two or more α-olefins, or copolymers of α-olefins and other compounds copolymerizable with the α-olefins, etc., can be cited. As α-olefins, 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, 1-eicosene, etc. can be cited. In addition, as other compounds, for example, compounds having polyunsaturated bonds such as conjugated dienes and non-conjugated dienes, or vinyl acetate, acrylic acid esters, etc. can be cited. Preferred polyolefin resins include, specifically, low-density polyethylene, medium-density polyethylene or high-density polyethylene, linear low-density polyethylene, polypropylene, α-olefin copolymers (ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc.), and the like.

[0032] Unsaturated carboxylic acids, their anhydrides or their derivatives are compounds having an ethylenically unsaturated bond and a carboxyl group, anhydride or 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, crotonic acid, isocrotonic acid, terminal cis-bicyclo[2.2.1]hept-2,3-dicarboxylic acid [nadic acid], methyl-terminal cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid [methylnadic acid] and the like; 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, 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, itaconic anhydride, etc. are preferred, and maleic anhydride is particularly preferred.

[0033] As maleic anhydride modified polyolefin resin, maleic anhydride modified polyethylene resin, maleic anhydride modified polypropylene resin, maleic anhydride modified α-olefin copolymer, maleic anhydride modified styrene-ethylene / butylene-styrene copolymer (SEBS), etc. If specific examples are given, for example, as maleic anhydride modified polyethylene resin and maleic anhydride modified polypropylene resin, "Admer (trade name)" manufactured by Mitsui Chemicals, "MODIC (trade name)" manufactured by Mitsubishi Chemical Corporation, etc., as maleic anhydride modified α-olefin copolymer, "Tafmer (trade name)" manufactured by Mitsui Chemicals, etc., can be listed, and as maleic anhydride modified styrene-ethylene / butylene-styrene copolymer, "TUFTEC (trade name)" manufactured by Asahi Kasei Corporation, etc. can be listed.

[0034] The modified polyolefin resin is added to the resin composition for sliding parts, and the obtained molded product (sliding parts) plays a role in improving mechanical properties such as impact resistance and elongation. The amount of the modified polyolefin resin is 0.1 to 5% by mass, preferably 0.5 to 3% by mass. When the amount of the modified polyolefin resin is less than 0.1% by mass, the above-mentioned effect of improving mechanical properties cannot be fully exerted, and when the amount exceeds 5% by mass, the heat resistance and chemical resistance unique to the polyphenylene sulfide resin may be impaired.

[0035] In the present invention, polysulfone resins, polyetherimide resins, and polyphenylene ether resins are used as amorphous polymers. Polysulfone resins are polymers containing a sulfonyl group (-SO2-) in the constituent molecules, and examples thereof include polyethersulfone resins represented by the following formula (1), polysulfone resins represented by the following formula (2), and polyphenylsulfone resins represented by the following formula (3). Specifically, examples of the polyethersulfone resin include "Sumikaexcel (trade name)" manufactured by Sumitomo Chemical, "Mitsui PES (trade name)" manufactured by Mitsui Chemicals, "Veradel (trade name)" manufactured by Solvay, and "Ultrazone E series (trade name)" manufactured by BASF. Examples of the polysulfone resin include "Udel (trade name)" manufactured by Solvay, and "Ultrazone S series (trade name)" manufactured by BASF. Examples of the polyphenylsulfone resin include "Redel (trade name)" manufactured by Solvay, "Ultrazone P series (trade name)" manufactured by BASF, and "CERAMER 60 (trade name)" manufactured by CERAMER.

[0036] [Chemistry 1]

[0037]

[0038] [Chemistry 2]

[0039]

[0040] [Chemistry 3]

[0041]

[0042] Examples of the polyetherimide resin include "Ultem (trade name)" manufactured by SABIC; examples of the polyphenylene ether resin include "Zylon (trade name)" manufactured by Asahi Kasei Corporation, "Iupiace (trade name)" manufactured by Mitsubishi Engineering-Plastics Corporation, and "Noryl (trade name)" manufactured by SABIC.

[0043] The amorphous polymer is added to the resin composition for sliding parts to improve the moldability of the resin composition for sliding parts and also improve the toughness and wear resistance of the obtained molded product (sliding parts). The amount of the amorphous polymer is 0.5 to 5% by mass, preferably 1 to 3% by mass. When the amount is less than 0.5% by mass, the above effect cannot be fully exerted, and when the amount exceeds 5% by mass, the moldability may be deteriorated.

[0044] In the present invention, at least one selected from phosphates, carbonates, and sulfates may be blended as an additional component.

[0045] Phosphates, carbonates, and sulfates themselves are not substances that exhibit lubricity like solid lubricants such as graphite and molybdenum disulfide, but by being added to a resin composition for sliding parts, they have the effect of improving the film formation of a lubricating coating such as tetrafluoroethylene resin on the surface of the mating part (sliding surface) during sliding with the mating part, thereby improving the sliding characteristics of the sliding part.

[0046] As phosphates, carbonates and sulfates, salts of alkali metals and alkaline earth metals are preferred; for example, as phosphates, there may be listed trilithium phosphate, tricalcium phosphate, dicalcium phosphate, dimagnesium phosphate, lithium pyrophosphate, calcium pyrophosphate, magnesium pyrophosphate, lithium metaphosphate, calcium metaphosphate, magnesium metaphosphate, etc.; as carbonates, there may be listed calcium carbonate, magnesium carbonate, barium carbonate, strontium carbonate, etc.; as sulfates, there may be listed calcium sulfate, barium sulfate, etc.

[0047] The amount of phosphate, carbonate, and sulfate is 0.1 to 10% by mass, preferably 1 to 5% by mass. When the amount of phosphate is less than 0.1% by mass, the effect of improving the film-forming property of the lubricating film cannot be fully exerted, and when the amount of phosphate exceeds 10% by mass, the amount of lubricating film formed on the surface of the mating part becomes too much, which reduces the wear resistance.

[0048] The resin composition for sliding parts of the present invention is basically composed of the above-mentioned composition, but in the present invention, in addition to these components, additional components may be added within the scope that does not significantly impair the effect of the invention. For example, non-fibrous inorganic fillers, lubricating oils such as mineral oil, ester oil, silicone oil, wax, pigments such as carbon black, etc. may also be added. Examples of non-fibrous inorganic fillers include silicates such as talc, clay, mica, kaolin, sericite, bentonite, aluminum silicate, and metal oxides such as silicon oxide (silicon dioxide), magnesium oxide, titanium oxide, and iron oxide. These non-fibrous inorganic fillers may be pre-treated with coupling agents such as silanes and titanates to improve the adhesion with the base material resin.

[0049] The resin composition for sliding parts of the present invention can be produced by weighing the components so that the amount in the composition is within the above range, placing the components in a conventional kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender, a kneader, etc., and performing melt kneading.

[0050] Usually, the above essential components and the additional components as required, the crosslinking catalyst, etc. are kneaded in an extruder or the like to form pellets for processing, but the components can also be directly supplied to a molding machine, and the molding can be performed while kneading in the composition. In addition, the B component or the C component can be kneaded in advance to form a high-concentration masterbatch, and it can be mixed and mixed with other components such as the A component or directly molded while being diluted.

[0051] Example

[0052] In the following examples, the following materials were used as polyphenylene sulfide resin, high molecular weight tetrafluoroethylene resin, low molecular weight tetrafluoroethylene resin, ultrahigh molecular weight polyethylene resin, modified polyolefin resin, amorphous polymer, phosphate, sulfate, lubricant and pigment. In addition, the following materials are all shown by trade name.

[0053] 〔A〕Polyphenylene sulfide resin

[0054] (A-1) "Ecotran N-200" manufactured by Teijin

[0055] 〔B〕High molecular weight tetrafluoroethylene resin

[0056] (B-1) Polyflon M-12 manufactured by Daikin Industries

[0057] (B-2) "KT300M" manufactured by Kitamura Co., Ltd.

[0058] 〔C〕Low molecular weight tetrafluoroethylene resin

[0059] (C-1) "Dyneon TF9207Z" manufactured by 3M

[0060] (C-2) Fluon L169J manufactured by AGC Corporation

[0061] 〔D〕Ultra-high molecular weight polyethylene resin

[0062] (D-1) "Modified Lubmer LY1040" manufactured by Mitsui Chemicals

[0063] (D-1) "Mipelon XM-220" manufactured by Mitsui Chemicals

[0064] 〔E〕Modified polyolefin resin

[0065] (E-1) Ethylene ionomer "Himilan 1855" manufactured by Mitsui & Dow Polychemicals

[0066] (E-2) Epoxy-containing polyolefin resin "BONDFAST E" manufactured by Sumitomo Chemical Co., Ltd.

[0067] [F] Amorphous polymer

[0068] (F-1) Polyethersulfone resin "Sumikaexcel 4800G" manufactured by Sumitomo Chemical Co., Ltd.

[0069] (F-2) Polyphenylsulfone resin "CERAMER 60" manufactured by CERAMER

[0070] 〔G〕Phosphate

[0071] (G-1) Calcium pyrophosphate (manufactured by Yoneyama Chemical Co., Ltd.)

[0072] (G-2) Trilithium phosphate (manufactured by Taihei Chemical Industry Co., Ltd.)

[0073] 〔H〕Sulfate

[0074] (H-1) Barium sulfate "BMH-60" manufactured by Sakai Chemical Industry Co., Ltd.

[0075] 〔I〕Lubricant

[0076] (I-1) Wax "Licowax PED191" manufactured by Clariant Chemicals

[0077] 〔J〕Pigment

[0078] (J-1) Carbon black "BP4350" manufactured by Cabot Corporation

[0079] (Examples 1 to 15 and Comparative Examples 1 to 12)

[0080] The above materials were used as the components, respectively, and the component compositions shown in Table 1, Table 2 and Table 3 were blended, and melt-kneaded at 290° C. using a twin-screw extruder to obtain a pelletized composition. Next, the pellets were made into test pieces (square plates with a length of 30 mm, a width of 30 mm, and a thickness of 3 mm) using an injection molding machine at a molding temperature of 300° C. and a mold temperature of 140° C.

[0081] The test pieces obtained as described above were subjected to the sliding test shown below, and the friction coefficient and the wear amount were measured. The bending strength and the formability were evaluated. The results are shown in Tables 1, 2, and 3.

[0082] (evaluate)

[0083] <Sliding test 1>

[0084] Movement mode: thrust unidirectional rotation

[0085] Surface pressure: 100kgf / cm 2

[0086] Speed: 1m / min

[0087] Time: 20 hours

[0088] Matching parts: SUS304 (Ra0.15 (μm))

[0089] Lubrication conditions: No lubrication

[0090] <Sliding test 2>

[0091] Movement mode: thrust unidirectional rotation

[0092] Surface pressure: 10kgf / cm 2

[0093] Speed: 30m / min

[0094] Time: 20 hours

[0095] Matching parts: SUS304 (Ra0.15 (μm))

[0096] Lubrication conditions: No lubrication

[0097] <Sliding Test 3>

[0098] Movement mode: thrust unidirectional rotation

[0099] Surface pressure: 100kgf / cm 2

[0100] Speed: 1m / min

[0101] Time: 20 hours

[0102] Matching parts: SUS304 (Ra0.32 (μm))

[0103] Lubrication conditions: No lubrication

[0104] <Bending Strength>

[0105] Using an injection molding machine SE-50DUZ manufactured by Juhu Heavy Machinery Industry, a bending test piece with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm was molded at a resin temperature of 300°C and a mold temperature of 140°C. Using this test piece, the bending strength was measured in accordance with JIS-K7171 under the conditions of a support distance of 100 mm, a crosshead speed of 5 mm / min, a temperature of 23°C, and a relative humidity of 50%.

[0106] <Moldability 1>

[0107] A molded product (sliding component) was molded from the pellets using an injection molding machine, and the presence or absence of burrs in the molded product was visually observed and evaluated.

[0108] Evaluation criteria: ○: good, ×: unacceptable

[0109] <Moldability 2>

[0110] A molded product (sliding part) was molded from the pellets using an injection molding machine, and the appearance of the molded product (burning due to gas, foaming, aggregation of additives) was visually observed and evaluated.

[0111] Evaluation criteria: ○: good, ×: unacceptable

[0112] [Table 1]

[0113]

[0114] [Table 2]

[0115]

[0116] [Table 3]

[0117]

[0118] As can be seen from the above test results, in Examples 1 to 15 in which all components were blended in amounts within the present invention, high sliding performance was achieved, bending strength was also high, and there was no problem of burr generation or poor appearance in the molded products.

[0119] In Comparative Example 1, in which the amount of tetrafluoroethylene resin blended is less than the range of the present invention and the amount of high molecular weight tetrafluoroethylene resin blended is less than the preferred range of the present invention, the reinforcement and viscosity increase caused by the fiberization of the high molecular weight tetrafluoroethylene resin are insufficient, resulting in poor molding such as low bending strength and burrs on the molded product. When the amount of high molecular weight tetrafluoroethylene resin blended is increased, the bending strength is improved by the fiberization of the high molecular weight tetrafluoroethylene, but in Comparative Example 2, the overall amount of tetrafluoroethylene resin blended is more than the range of the present invention, resulting in a problem that the extrusion moldability is deteriorated and the product cannot be manufactured.

[0120] In Comparative Example 3, in which the amount of tetrafluoroethylene resin blended was less than the range of the present invention and the amount of low molecular weight tetrafluoroethylene resin blended was less than the preferred range of the present invention, sufficient lubricity was not obtained, the friction coefficient was high and the amount of wear was increased compared to the examples. In Comparative Examples 2 and 4, in which the amount of tetrafluoroethylene resin blended was more than the range of the present invention and the amount of low molecular weight tetrafluoroethylene resin blended was more than the preferred range of the present invention, the amount of polyphenylene sulfide resin serving as the matrix was insufficient, and extrusion molding was impossible.

[0121] Compared with the embodiment, the comparative example 5 in which the amount of ultra-high molecular weight polyethylene resin is less than the range of the present invention has a high friction coefficient and an increased amount of wear, especially under the test condition 3 of sliding with a mating part with a rough surface, the wear resistance is significantly reduced. This is because the ultra-high molecular weight polyethylene resin can quickly form a soft resin transfer film on the mating part during the initial running-in of sliding, making the surface of the mating part smooth. When observing the surface of the mating part after the test of the test condition 3 of Example 1, it is confirmed that the soft resin transfer film of the ultra-high molecular weight polyethylene resin is filled in the concave and convex concave parts on the surface of the mating part, and the surface of the mating part is smoothed. In the comparative example 6 in which the amount of ultra-high molecular weight polyethylene resin is more than the range of the present invention, the ultra-high molecular weight polyethylene is thermally degraded, and due to the degraded gas, burning occurs in the molded product, resulting in poor molding. In addition, the problem of mold contamination by gas components occurs.

[0122] In Comparative Example 7, in which no modified polyolefin resin was added, the sliding performance and bending strength were reduced, and a molding defect in which burrs were generated occurred in the molded product. The modified polyolefin resin is thermally degraded at the molding temperature of the polyphenylene sulfide resin, so if it is added excessively, the molded product will be burned and the appearance will be deteriorated. Therefore, in Comparative Example 8, in which the amount of modified polyolefin resin added was larger than the range of the present invention, the sliding performance was reduced and the appearance was poor.

[0123] In Comparative Example 9 in which the amorphous polymer was not added, the wear resistance was reduced and burrs were generated in the molded product. When the amorphous polymer was added, the wear resistance was improved, but in Comparative Example 10 in which the amount of the amorphous polymer added was larger than the range of the present invention, the surface roughness of the molded product became large, resulting in poor appearance.

[0124] It can be seen that in Comparative Example 7 without the modified polyolefin resin and Comparative Example 9 without the amorphous polymer, burrs were generated on the molded product, and the generation of burrs could not be suppressed by adding the modified polyolefin resin and the amorphous polymer separately. Therefore, in order to obtain the effect of suppressing burrs, it is effective to use the modified polyolefin resin and the amorphous polymer in combination.

[0125] Several embodiments of the present invention have been described above, but these embodiments are shown as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope or subject matter of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A resin composition for sliding parts, characterized in that The present invention relates to 40 to 80% by mass of polyphenylene sulfide resin, 1 to 10% by mass of high molecular weight tetrafluoroethylene resin, 10 to 35% by mass of low molecular weight tetrafluoroethylene resin, 2 to 20% by mass of ultrahigh molecular weight polyethylene resin, 0.1 to 5% by mass of modified polyolefin resin and 0.5 to 5% by mass of polysulfone resin as additives.

2. The resin composition for sliding parts according to claim 1, wherein The modified polyolefin resin is selected from ethylene-based ionomers, polyolefin resins having epoxy groups in the molecule, and polyolefin resins graft-modified with unsaturated carboxylic acids, their anhydrides, or their derivatives.

3. The resin composition for sliding parts according to claim 2, wherein The polyolefin resin graft-modified by unsaturated carboxylic acid, its anhydride or their derivatives is selected from maleic anhydride modified polyethylene resin, maleic anhydride modified polypropylene resin, maleic anhydride modified ethylene-α-olefin copolymer, maleic anhydride modified styrene-ethylene / butylene-styrene copolymer.

4. The resin composition for sliding parts according to claim 1, wherein The polysulfone resin is selected from polyethersulfone resin, polysulfone resin and polyphenylsulfone resin.

5. The resin composition for sliding parts according to claim 1, wherein At least one selected from phosphates, carbonates and sulfates is blended as an additional component in an amount of 0.1 to 10% by mass.

6. The resin composition for sliding parts according to claim 5, wherein The phosphate, carbonate and sulfate are salts of alkali metals or alkaline earth metals.

7. A sliding component, characterized in that: The invention comprises the resin composition for sliding parts according to any one of claims 1 to 6.

Images