Sliding resin composition and sliding resin member

Abstract

Provided is a sliding resin composition in which prescribed heterogeneous domains derived from blending components are formed and abnormal noises such as creaking noises are few even if the composition is molded or processed into a variety of resin sliding members. This sliding resin composition and this sliding resin member derived therefrom contain at least components (A) and (B). When domains which are derived from component (B) and have a circle-equivalent diameter of 10 µm or more are selected, the average value (φ1) of circle-equivalent diameters of the selected domains falls within the range 10-30 μm. (A) 100 parts by weight of at least one primary resin such as a polyacetal resin. (B) 1-70 parts by weight of an elastomer such as an olefinic elastomer

Description

Sliding resin composition and sliding resin member

[0001] The present invention relates to a sliding resin composition and a sliding resin member (hereinafter, sometimes simply referred to as a resin composition and a sliding member, respectively). In particular, the present invention relates to a sliding resin composition that is derived from a sliding resin composition in which domains are formed non-uniformly and that generates little abnormal noise such as creaking even when molded into a sliding member, and to a sliding resin member derived from such a sliding resin composition.

[0002] Polyacetal resins, polyamide resins, polybutylene terephthalate resins, and the like each have excellent mechanical properties, as well as excellent sliding properties such as friction and wear, heat resistance, chemical resistance, and electrical properties, and are used as engineering plastics in resin compositions for sliding members in a wide range of fields, such as automobile parts, electronic and electrical parts, and general industrial machinery parts. Sliding members made of polyacetal resins and the like have excellent self-lubrication and wear resistance, but have a relatively high coefficient of friction. Furthermore, they have the problem of being prone to stick-slip due to fluctuations in the coefficient of friction during sliding, which in turn tends to generate unpleasant sliding friction noise (squeaking noise) due to stick-slip. Therefore, in order to further improve the sliding properties, various resin compositions for sliding members and various sliding members derived therefrom have been proposed.

[0003] For example, a sliding resin composition has been proposed that, when used as a sliding part, provides a sliding part with excellent sliding properties and wear resistance, regardless of whether the mating sliding part is made of plastic or metal, and a sliding part made using the same (see, for example, Patent Document 1). More specifically, the sliding resin composition contains, relative to 100 parts by weight of polyacetal resin, 0.5 to 15 parts by weight of an olefin-based elastomer, 0.1 to 5 parts by weight of a fatty acid ester having 12 or more carbon atoms, and 0.05 to 5 parts by weight of polytetrafluoroethylene fine powder, and a polyacetal sliding resin member derived therefrom.

[0004] Also proposed is a polyamide resin composition suitable for use in molding sliding parts that are required to have excellent moldability and heat stability, as well as excellent sliding properties, particularly wear resistance mediated by particles (hereinafter also referred to as dust) having high hardness, and excellent sliding stability (see, for example, Patent Document 2). More specifically, the polyamide resin composition for sliding parts contains a crystalline polyamide resin (A), a modified polyolefin resin (B) having a reactive functional group capable of reacting with a terminal group and / or a main chain amide group of the polyamide resin (A), a thermoplastic elastomer (C) having a reactive functional group capable of reacting with a terminal group and / or a main chain amide group of the polyamide resin (A), an antioxidant (D), and a mold release agent (E), and the modified polyolefin resin (B) and the thermoplastic elastomer (C) are dispersed in a matrix of the polyamide resin (A) in domains with particle sizes of 5 μm or less.

[0005] Furthermore, the applicant of the present invention has proposed a sliding resin composition and a sliding member derived therefrom that, which, when molded into a sliding member while maintaining good moldability, reduces the generation of squeak noise and improves sliding characteristics including load capacity, low friction, and wear resistance (see, for example, Patent Document 3). More specifically, the sliding resin composition and sliding member derived therefrom contain, in addition to a polyacetal resin as the main component, 1.5 to 7 wt % of ethylene-propylene-diene rubber, 0.5 to 3 wt % of a saponified ethylene-vinyl acetate copolymer (saponification degree of 50 to 100%), and 0.05 to 0.3 wt % of an ethylene-α-olefin copolymer, based on 100 wt % of the entire sliding resin composition, and are free of a formaldehyde scavenger and a carbon material.

[0006] Patent No. 3200279 (Claims, Example 1, etc.) Patent No. 6872155 (Claims, Example 1, etc.) Patent No. 6864472 (Claims, Example 1, etc.)

[0007] However, the polyacetal resin composition and sliding parts derived therefrom described in Patent Document 1 are limited to polyacetal resin as the main resin and require the dispersion of an olefin-based elastomer in the form of fine particles, resulting in poor versatility and insufficient suppression of squeak noise under more severe sliding conditions. Furthermore, in order to reduce the size and weight of parts, a synthetic resin is selected as the sliding mating material, and when sliding friction occurs between synthetic resins, stick-slip is likely to occur, and the prevention of squeak noise due to stick-slip is not necessarily sufficient. Furthermore, there are manufacturing problems, such as the large number of essential components constituting the polyacetal resin composition, the complex molding conditions for obtaining a uniformly mixed molded product, and the need for temperature control of each part of the molding machine during molding.

[0008] Furthermore, the sliding part described in Patent Document 2 requires that the main resin be limited to a crystalline polyamide resin (A), and that the modified polyolefin resin (B) having a predetermined functional group and the thermoplastic elastomer (C) having a predetermined functional group be dispersed in the crystalline polyamide resin (A) matrix to a particle size of 5 μm or less, resulting in poor versatility. Furthermore, the blending components, crystalline polyamide resin (A), modified polyolefin resin (B) having a predetermined functional group, thermoplastic elastomer (C) having a predetermined functional group, antioxidant (D), and mold release agent (E), must be contained in predetermined blending ratios and uniformly blended, resulting in manufacturing control difficulties. Furthermore, if the blending ratios vary during manufacturing, it becomes difficult to control the reactivity between the crystalline polyamide resin (A), the modified polyolefin resin (B) having a predetermined functional group, and the thermoplastic elastomer (C) having a predetermined functional group. Therefore, it becomes difficult to control the size of the domains (5 μm or less) resulting from these compounded components, and therefore, the prevention of creaking noises due to stick-slip tends to be insufficient.

[0009] Furthermore, although the sliding member described in Patent Document 3 can improve sliding properties such as friction and wear, the main resin component must be limited to polyacetal resin alone. Furthermore, the polyacetal resin composition contains 1.5 to 7 mass% of ethylene-propylene-diene rubber, 0.5 to 3 mass% of saponified ethylene-vinyl acetate copolymer, and 0.05 to 0.3 mass% of ethylene-α-olefin copolymer, based on 100 mass% of the entire polyacetal resin composition. However, the composition must substantially exclude formaldehyde scavengers and carbon materials. In other words, if a sliding member contains a predetermined amount of carbon black or the like as a formaldehyde scavenger and carbon material, the formulation becomes complicated. Furthermore, when various resins other than polyacetal resin are used as the main resin component, problems have been observed in that the prevention of squeaking noise due to stick-slip is not necessarily sufficient.

[0010] In view of the above problems, the present inventors have conducted extensive studies and found that, regardless of whether a predetermined amount of carbon material is used or not, by controlling the circle equivalent diameter and the like of a domain structure (hereinafter, may be simply referred to as a domain) derived from an olefin-based resin or the like as component (B) and formed in a predetermined non-uniform state relative to component (A), which is a main resin, the sliding characteristics of a resin sliding member derived from a sliding resin composition can be improved and, moreover, the generation of sliding friction noise (creaking noise) due to stick-slip can be prevented, thereby completing the present invention.

[0011] That is, according to the present invention, an object is to provide a sliding resin composition that uses various resins, not limited to (A) polyacetal resin, as a main resin, and disperses and blends (B) olefin-based resin or the like to form a domain structure having a predetermined non-uniform state, thereby reducing the generation of creaking noise and the like and exhibiting excellent sliding properties, and a sliding member made therefrom.

[0012] According to the present invention, there is provided a sliding resin composition comprising at least the following components (A) and (B), characterized in that domains having an equivalent circle diameter of 10 μm or more derived from component (B) that are non-uniformly dispersed in component (A) per unit area of ​​any cross section are selected, and the average value of the equivalent circle diameters of the selected domains (φ1, hereinafter sometimes referred to as the average value of domains of 10 μm or more derived from component (B) or simply the average value of the predetermined domains) is set to a value within a range of 10 to 30 μm, thereby solving the above-mentioned problems. (A) 100 parts by weight of at least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin; and (B) 1 to 70 parts by weight of an olefin-based elastomer, a styrene-based elastomer, or either one of the elastomers. By constructing the sliding resin composition in this manner, it is possible to disperse domains of 10 μm or larger derived from component (B) in a predetermined non-uniform state in the main resin (A) of various resins, as measured by image analysis or other methods. Furthermore, the presence of domains with a circle-equivalent diameter of 10 μm or larger derived from component (B) on the sliding surface can control adhesion (adhesion) of the resin composition even under severe sliding conditions, suppressing the occurrence of stick-slip and reducing the generation of squeaking noise. Therefore, by controlling the average value (φ1) of the predetermined domains, the occurrence of squeaking noise and other issues due to stick-slip can be reduced, and excellent sliding properties can be exhibited for a long period of time. Here, the state in which domains are non-uniformly dispersed means that the particle size distribution of the domains measured using image analysis or the like is not concentrated in a narrow range. For example, this can be recognized when the standard deviation (σ) of the equivalent circle diameters of all domains per unit area measured using image analysis is as wide as 0.8 μm or more. The average value (φ1) of a given domain is one indicator of whether the domain structure is non-uniform, and can usually be measured and calculated with high accuracy using image analysis under specified conditions.

[0013] Furthermore, when constructing the sliding resin composition of the present invention, it is preferable to select at least five domains per unit area derived from component (B), designated n1 to n5, in descending order of circle-equivalent diameter, and set the average circle-equivalent diameter of the selected domains (φ2; hereinafter, this may be referred to as the average of at least five domains derived from component (B) in descending order of circle-equivalent diameter, or simply as the maximum particle size of a given domain) to a value within the range of 10 to 130 μm. That is, by constructing the sliding resin composition in this manner, it is possible to quantitatively control the domain structure of component (B) relative to component (A), resulting in a domain structure having a predetermined non-uniformity. Therefore, the occurrence of creaking noises due to stick-slip and the like is reduced, and excellent sliding properties can be exhibited. Furthermore, the maximum particle size (φ2) of a given domain is also an indicator of the non-uniformity of the domains, and can usually be measured accurately using image analysis. That is, it has been found separately that when the number of domains for measuring the predetermined circle equivalent diameter is increased in order from one point, the sliding property saturates and shows a constant value at about four or five points.

[0014] Furthermore, when constructing the sliding resin composition of the present invention, it is preferable to set the area ratio of domains derived from component (B) having an equivalent circle diameter of 10 μm or more (φ3, hereinafter sometimes referred to as the area ratio of domains derived from component (B) having an equivalent circle diameter of 10 μm or more or simply the area ratio of the predetermined domains) per unit area to a value within the range of 0.5 to 20%. By constructing the sliding resin composition in this manner, the dispersibility of component (B) relative to component (A) can be quantitatively controlled to achieve non-uniform dispersion, thereby reducing the occurrence of creaking noises due to stick-slip and enabling the exhibiting of excellent sliding properties over a long period of time. The area ratio of the predetermined domains (φ3) is also an indicator of the non-uniform state of the domains, and can usually be measured accurately using image analysis.

[0015] Furthermore, when forming the sliding resin composition of the present invention, it is preferable to further include a lubricant as component (C), and to set the blending amount of component (C) to a value within the range of 0.1 to 10 parts by weight per 100 parts by weight of component (A). By blending a predetermined amount of lubricant as component (C) in this way, even when various resins are used as the main resin and molded into a sliding resin member, the generation of creaking noises and the like due to stick-slip can be further reduced over a long period of time, and excellent sliding properties can be exhibited.

[0016] Furthermore, in constructing the sliding resin composition of the present invention, it is preferable to further include a polyolefin resin other than component (B) as component (D), and to set the blending amount of this polyolefin resin to a value within the range of 1 to 10 parts by weight per 100 parts by weight of component (A). By blending a predetermined amount of polyolefin resin as component (D) in this way, it contributes to the appropriate dispersion of the various blending components including component (B), and therefore even when molded into a sliding resin member, the generation of creaking noises and the like due to stick-slip is further reduced over a long period of time, and excellent sliding properties can be exhibited.

[0017] Furthermore, when forming the sliding resin composition of the present invention, it is preferable to further include a carbon material as component (E), and to set the blending amount of component (E) to a value within the range of 0.01 to 10 parts by weight per 100 parts by weight of component (A). Carbon material (E), such as carbon black, absorbs or adsorbs lubricating oil and contributes to more appropriate dispersion, so that even when molded into a sliding resin member, the generation of creaking noises due to stick-slip can be further reduced over a long period of time.

[0018] Furthermore, in preparing the sliding resin composition of the present invention, it is preferable that the melt flow rate of component (A) be within the range of 3 to 100 g / 10 min. By using component (A) having such flow characteristics, it is possible to more reliably and stably form a non-uniformly dispersed state of component (B) and the like, even when using a general kneading machine such as an extruder.

[0019] In forming the sliding resin composition of the present invention, it is preferable that component (B) be at least one resin selected from the group consisting of ethylene-propylene copolymer (EPM), ethylene-propylene-diene copolymer (EPDM), ethylene-1-butene copolymer (EBR), ethylene-vinyl acetate copolymer (EVA), olefin-ethylenebutylene-olefin block copolymer (CEBC), styrene-butadiene copolymer (SBR), and styrene-ethylenebutylene-styrene copolymer (SEBS). The resin preferably has a Mooney viscosity ML(1+4) at 100°C of 40 to 110, a Mooney viscosity ML(1+4) at 125°C of 20 to 80, or a melt flow rate (190°C, 2.16 kg) of less than 3 g / 10 min. By configuring the sliding resin composition in this way, taking into consideration the Mooney viscosity of the component (B), etc., it is possible to appropriately control the size of the domains of 10 μm or more derived from the component (B), and to more reliably and stably form a non-uniform dispersion state, even when a general kneading machine such as an extruder is used.

[0020] Another aspect of the present invention is a sliding resin member comprising, as a constituent component, a sliding resin composition containing the following components (A) and (B), in which domains derived from at least component (B) and having an equivalent circle diameter of 10 μm or more are dispersed in a predetermined non-uniform state within component (A): The sliding resin member is characterized in that domains derived from component (B) having an equivalent circle diameter of 10 μm or more per unit area are selected, and the average equivalent circle diameter (φ1) of the selected domains is set to a value within the range of 10 to 30 μm: (A) 100 parts by weight of at least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin; (B) 1 to 70 parts by weight of an olefin-based elastomer, a styrene-based elastomer, or either one of the elastomers. By constructing the sliding resin member in this manner, it is possible to use various resins as the main resin and, regardless of whether a carbon material is blended, to disperse domains of 10 μm or larger derived from component (B) in a predetermined non-uniform state relative to component (A). Therefore, the occurrence of squeaks and other noises due to stick-slip is reduced, and excellent sliding characteristics can be exhibited over a long period of time. Here, unless otherwise specified, the average value (φ1), maximum particle size (φ2), and area ratio (φ3) of the predetermined domains are values ​​per unit area.

[0021] FIG. 1(a) is a diagram illustrating the relationship between the average value (φ1 (μm)) of domains of 10 μm or more derived from component (B) in a sliding resin composition and the allowable surface pressure (MPa). FIG. 1(b) is a diagram illustrating the relationship between the average value (φ1 (μm)) of domains and the allowable surface pressure (MPa) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 2(a) is a diagram illustrating the relationship between the average value (φ2 (μm)) of five domains derived from component (B) in a sliding resin composition, ordered from the largest, and the allowable surface pressure (MPa). FIG. 2(b) is a diagram illustrating the relationship between the average value (φ2 (μm)) of five domains in a sliding resin composition, ordered from the largest, and the allowable surface pressure (MPa) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 3( a) is a diagram provided for explaining a situation in which the average value (φ2 (μm)) of five domains derived from the component (B) in the present invention (Example 5) was selected in descending order of size. FIG. 3( b) is a diagram (photograph) provided for explaining a situation in which the average value (φ2 (μm)) of five domains derived from the component (B) in the comparative example 1 was selected in descending order of size. FIG. 4( a) is a diagram provided for explaining the relationship between the area ratio (φ3 (%)) of a predetermined domain and the allowable surface pressure (MPa) in a sliding resin composition. FIG. 4( b) is a diagram provided for explaining the relationship between the area ratio (φ3 (%)) of a predetermined domain and the allowable surface pressure (MPa) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 5( a) is a diagram provided for explaining the relationship between the maximum particle size (φ2 (μm)) of a predetermined domain and the average value (φ1 (μm)) of the predetermined domain in a sliding resin composition. 5(b) is a diagram illustrating the relationship between the average particle size (φ1 (μm)) of a predetermined domain and the area ratio (φ3 (%)) of the predetermined domain in a sliding resin composition. Also, FIG. 5(c) is a diagram illustrating the relationship between the maximum particle size (φ2 (μm)) of a predetermined domain and the area ratio (φ3 (%)) of the predetermined domain in a sliding resin composition.6(a) to 6(c) are diagrams provided to explain the relationship between the average value (φ1 (μm)) of a predetermined domain, the maximum particle size (φ2 (μm)) of a predetermined domain, and the area ratio (φ3 (%)) of a predetermined domain in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 7(a) is a diagram provided to explain the relationship between the average value (φ1 (μm)) of a predetermined domain and the coefficient of friction (-) in a sliding resin composition. FIG. 7(b) is a diagram provided to explain the relationship between the average value (φ1 (μm)) of a predetermined domain and the coefficient of friction (-) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 8( a) is a diagram illustrating the relationship between the maximum particle size (φ2 (μm)) of a predetermined domain and the coefficient of friction (−) in a sliding resin composition. FIG. 8( b) is a diagram illustrating the relationship between the maximum particle size (φ2 (μm)) of a predetermined domain and the coefficient of friction (−) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 9( a) is a diagram illustrating the relationship between the area ratio (φ3 (%)) of a predetermined domain and the coefficient of friction (−) in a sliding resin composition. FIG. 9( b) is a diagram illustrating the relationship between the area ratio (φ3 (%)) of a predetermined domain and the coefficient of friction (−) in a similar sliding resin composition except that a sliding resin composition containing a carbon material was used. FIG. 10 is a diagram illustrating the relationship between the circle-equivalent diameter (μm) of the domain derived from component (B) and the relative frequency (%) in the present invention (Example 5). Fig. 11 is a diagram provided to explain the relationship between the circle-equivalent diameter (µm) of domains derived from component (B) and the relative frequency (%) in Comparative Example 3. Figs. 12(a) and 12(b) are diagrams provided to explain the non-uniform dispersion state of domains derived from component (B) in the present invention (Examples 12 and 15), respectively.

[0022] [First Embodiment] The first embodiment provides a sliding resin composition comprising at least the following components (A) and (B), wherein domains having an equivalent circle diameter of 10 μm or more derived from component (B) that are non-uniformly dispersed in component (A) per unit area are selected, and the average value of the equivalent circle diameters (φ1) of the selected domains is set to a value within the range of 10 to 30 μm, thereby solving the above-mentioned problems: (A) 100 parts by weight of at least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin; (B) 1 to 70 parts by weight of an olefin-based elastomer and / or a styrene-based elastomer. The sliding resin composition of the first embodiment will now be described in detail with reference to the accompanying drawings as appropriate.

[0023] 1. Component (A) (1) Type The type of component (A) may be at least one main resin selected from the group consisting of polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate resin (PBT), and polycarbonate resin (PC).

[0024] Among these, polyacetal resin contains oxymethylene groups (-CH ２ O-) as a main structural unit, and polyacetal resins include polyacetal homopolymers consisting of only oxymethylene units and polyacetal copolymers containing oxymethylene units and comonomer units. While either polyacetal homopolymers or polyacetal copolymers can be used, polyacetal copolymers are more preferable in terms of thermal stability.

[0025] Specific examples of such polyacetal homopolymers include "Delrin" (trade name) manufactured by DuPont USA and "Tenac" (trade name) manufactured by Asahi Kasei Corp. Specific examples of polyacetal copolymers include "Duracon" (trade name) manufactured by Polyplastics Co., Ltd., "Iupital" (trade name) manufactured by Global Polyacetal Corp., and "Tenac C" (trade name) manufactured by Asahi Kasei Corp.

[0026] Polyamide resin (nylon) is a polymer compound having an amide bond (—NH—CO—) in the main chain. Examples include aliphatic polyamides, aromatic polyamides, and wholly aromatic polyamides.

[0027] Specific examples of such polyamide resins include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sebacamide (nylon 410), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene sebacamide (nylon 1010), polydecamethylene dodecamide (nylon 1012), polyundecane amide (nylon 11), polydodecanamide (nylon 12), and polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), which have a melting point of 150°C or higher. and semi-aromatic nylons such as polyhexamethylene terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 6I), polymetaxylylene adipamide (nylon MXD6), polymetaxylylene sebacamide (nylon MXD10), polynonamethylene terephthalamide (nylon 9T), and polydecamethylene terephthalamide (nylon 10T), which can be obtained by polymerizing an aliphatic and / or alicyclic diamine with an aromatic carboxylic acid, an aromatic diamine with an aliphatic and / or alicyclic dicarboxylic acid, a mixture of these, or these with a lactam or an aminocarboxylic acid.

[0028] Specific examples of such polyamide (nylon) resins include nylon 6, nylon 66, and nylon 610 (trade name "Amilan") manufactured by Toray Industries, Inc., nylon 66 (trade name "Leona") manufactured by Asahi Kasei Corporation, nylon 6 and nylon 66 (trade name "Zytel") manufactured by DuPont, and nylon 11 and nylon 12 (trade name "Rilsan") manufactured by Arkema.

[0029] Polybutylene terephthalate resin (PBT) is a polymer compound produced by condensation polymerization of terephthalic acid or dimethyl terephthalate with 1,4-butanediol, and is a type of polyester.

[0030] Specific examples of polybutylene terephthalate resins include "Novaduran" manufactured by Mitsubishi Chemical Corporation, "Trecon" manufactured by Toray Industries, Inc., and "Duranex" manufactured by Polyplastics Co., Ltd.

[0031] Polycarbonate resin (PC) is a polymer compound produced by interfacial polymerization using bisphenol A and carbonyl chloride as monomers, or by melt polymerization using transesterification of bisphenol A and diphenyl carbonate.

[0032] Specific examples of polycarbonate resins include "Toughlon" manufactured by Idemitsu Kosan Co., Ltd., "Kotex" manufactured by Kotec Corporation, "Lexan Resin" manufactured by SABIC Japan, and "Iupilon" manufactured by Mitsubishi Engineering Plastics Corporation.

[0033] (2) Melt Flow Rate (MFR) Furthermore, with regard to component (A), it is preferable to set its MFR to a value within the range of 3 to 100 g / 10 min. The reason for this is that if the MFR of component (A) is less than 3 g / 10 min, it may be difficult to obtain good moldability during resin molding, or low-molecular-weight substances may be more likely to bleed out. Furthermore, the viscosity difference with component (B) may be small, making it difficult to obtain the desired non-uniform dispersion state. On the other hand, if the MFR of component (A) exceeds 100 g / 10 min, although good moldability is obtained, durability and mechanical properties may be significantly reduced when a sliding member is formed. Therefore, a value within the range of 5 to 50 g / 10 min is more preferable, and a value within the range of 7 to 30 g / 10 min is even more preferable. The melt flow rate (MFR) can be measured in accordance with ISO 1133 (JIS K 7210) and is measured as the outflow weight per unit time under test conditions specified for each material. The test conditions specified for each material are a temperature of 190°C and a load of 2.16 kg (JIS K 7364-2) for polyacetal resin, and a temperature of 300°C and a load of 1.2 kg (JIS K 6719-2) for polycarbonate resin. On the other hand, when no test conditions are specified, such as for polyamide resin or polybutylene terephthalate resin, the value measured under a load of 2.16 kg at a temperature 10 to 20°C lower than the melt (resin) temperature in the injection molding conditions for each material (PA: JIS K 6920-2, PBT: JIS K 6937-2) is used.

[0034] 2. Component (B) (1) Types This product is characterized by blending a predetermined amount of an olefin-based elastomer, a styrene-based elastomer, or either one of the elastomers as component (B) with component (A), which is the main resin. While the following materials are preferably used alone, it is also preferable to use multiple materials. For example, by combining a (B) component that disperses at 10 μm or more with a (B) component that disperses at less than 10 μm, a higher allowable surface pressure can be achieved.

[0035] Examples of olefin-based elastomers include at least one ethylene-based copolymer or diene-based copolymer. Examples of ethylene-based copolymers include, but are not limited to, copolymers of ethylene and an α-olefin, copolymers of ethylene, an α-olefin, and a diene, copolymers of ethylene and a carboxylic acid ester, and copolymers of ethylene and an α,β-unsaturated carboxylic acid. Hydrogenated polymer-based copolymers such as olefin-ethylenebutylene-olefin block copolymers (CEBC) are also included. Ionomer resins are ionic copolymers obtained by adding metal ions having a valence of 1 to 3 to copolymers of α-olefins containing ethylene and α,β-unsaturated carboxylic acids. Examples of α-olefins include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene.

[0036] Furthermore, examples of copolymers of ethylene, an α-olefin, and a diene include an ethylene-propylene-diene copolymer, an ethylene-butene-diene copolymer, etc. Examples of diene monomers contained therein include 5-vinyl-2-norbornene (VNB), 5-ethylidene-2-norbornene (ENB), dicyclopentadiene (DCPD), 1,4-hexadiene (HD), etc.

[0037] Examples of copolymers of ethylene and carboxylic acid esters include ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer (EMMA), and ethylene-vinyl acetate copolymer (EVA). Ethylene-vinyl acetate copolymers also include their saponified products. Examples of α,β-unsaturated carboxylic acids copolymerized with ethylene include acrylic acid, methacrylic acid, maleic acid, and fumaric acid.

[0038] Examples of the diene copolymer include polybutadiene, polyisoprene, isobutene-isoprene copolymer, and hydrogenated products thereof.

[0039] Among these, at least one of ethylene-propylene copolymer (EPM), ethylene-propylene-diene copolymer (EPDM), ethylene-1-butene copolymer (EBR), ethylene-vinyl acetate copolymer (EVA), olefin-ethylenebutylene-olefin block copolymer (CEBC), and the like is particularly preferred.

[0040] On the other hand, styrene-based elastomers include copolymers having a styrene component or hydrogenated products thereof. More specific examples include, but are not limited to, at least one of styrene-butadiene-styrene block polymer (SBS), styrene-ethylenebutylene-styrene block polymer (SEBS), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), styrene-isoprene rubber (SIR), styrene-isoprene-styrene block polymer (SIS), and styrene-ethylenepropylene-styrene block polymer (SEPS). Particularly preferred styrene-based elastomers are at least one of styrene-butadiene rubber (SBR), styrene-ethylenebutylene-styrene block polymer (SEBS), and the like.

[0041] (2) Viscosity Furthermore, component (B) is preferably a resin having a Mooney viscosity ML(1+4) at 100°C of 40 to 110, a Mooney viscosity ML(1+4) at 125°C of 20 to 80, or a melt flow rate (190°C, 2.16 kg) of less than 3 g / 10 min. More specifically, it is preferable to use a resin having any of the following structures (i) to (iii). Structure (i): Mooney viscosity ML(1+4) at 100°C of 40 to 110. Structure (ii): A range that does not include structure (i) and has a Mooney viscosity ML(1+4) at 125°C of 20 to 80. Structure (iii): A range that does not include structure (i) and structure (ii), and has a melt flow rate (190°C, 2.16 kg) of less than 3 g / 10 min.

[0042] (3) Amount of Blending: The present invention is characterized in that the amount of blending component (B) is within the range of 1 to 70 parts by weight per 100 parts by weight of component (A), which is the main resin. The reason for this is that if the amount of blending component (B) is less than 1 part by weight, not only will the sliding characteristics of the sliding member made from the sliding resin composition, such as load-bearing capacity, low friction, and wear resistance, be unsatisfactory, but the sliding member may not be sufficiently effective in preventing squeaking noise. On the other hand, if the amount of blending component (B) exceeds 70 parts by weight, the surface smoothness of the molded product may be impaired, resulting in poor appearance and increased susceptibility to molding defects such as peeling. Therefore, the amount of blending component (B) is more preferably within the range of 3 to 20 parts by weight, and even more preferably within the range of 5 to 15 parts by weight, per 100 parts by weight of component (A).

[0043] (4) Average value (φ1) of domains of 10 μm or more derived from component (B) Furthermore, the present invention is characterized in that domains derived from component (B) having an equivalent circle diameter of 10 μm or more per unit area are selected, and the average equivalent circle diameter, φ1, of the selected domains is set to a value within the range of 10 to 30 μm. Here, the equivalent circle diameter refers to the diameter of a circle assuming an area equal to the area of ​​the particle, and the average equivalent circle diameter can be calculated as a value equivalent to the arithmetic mean particle diameter (hereinafter the same), which is the average particle diameter based on JIS Z 8819-2:2019. More specifically, the equivalent circle diameter can usually be measured by an image analysis method in accordance with JIS Z 8827-1:2018. Furthermore, the unit area is not particularly limited, but an example is approximately 108,000 μm. 2 It is preferable that the observation range is about (1200 μm × 900 μm). For example, about 40,000 μm 2 range and approximately 500,000 μm 2 Even in the case of the range of φ1 and φ2 to φ4 described later, the values ​​are 108,000 μm 2 It has been separately found that there is almost no difference compared to when viewed in

[0044] With this configuration, the reason why the circle equivalent diameter of the predetermined domains is 10 μm or more is to confirm that the presence of such relatively large domains results in a non-uniform domain structure. That is, this reduces the friction coefficient while increasing the allowable surface pressure, and ultimately makes it possible to effectively suppress the generation of abnormal noise. Conversely, if the average value (φ1) of the predetermined domains is less than 10 μm, that is, if there are no domains of 10 μm or more, it may be difficult to effectively suppress the generation of abnormal noise even if the domains are dispersed non-uniformly.

[0045] On the other hand, if the average value (φ1) of the predetermined domain exceeds 30 μm, the surface smoothness of the molded product may be impaired, the appearance may deteriorate, and molding defects such as peeling may become more likely to occur. Therefore, the average value (φ1) of the predetermined domain is more preferably 20 μm or less, and even more preferably 15 μm or less. Furthermore, since the average value (φ1) of the predetermined domain is calculated based on domains having an equivalent circle diameter of 10 μm or more, it is preferable that the value be more than 10 μm.

[0046] Furthermore, it can be recognized when the standard deviation (σ) of the equivalent circle diameters in all domains per unit area measured by image analysis is 0.8 μm or more. Therefore, it is more preferable that the standard deviation (σ) of the equivalent circle diameters in all domains is a value within the range of 1 to 10 μm, and even more preferably a value within the range of 1.5 to 5 μm. Note that, within the range of standard deviation centered on the average value of the particle size distribution of all domains, the positive side of the average value is defined as +σ, and the negative side is defined as -σ.

[0047] Here, referring to FIG. 1( a), the relationship between the average value (φ1) of domains of 10 μm or more derived from component (B) and the allowable surface pressure will be described for the case where a sliding resin composition containing no carbon material is used. That is, in FIG. 1( a), the horizontal axis shows the average value (φ1) of the predetermined domains in a sliding resin composition containing predetermined blending components, and the vertical axis shows the allowable surface pressure (MPa) measured by the method described in Example 1, etc. As can be seen from the characteristic curve in FIG. 1( a), the presence of domains of 10 μm or more allows a high allowable surface pressure of 3 MPa or more. However, as the average value (φ1) of the predetermined domains increases and falls within a certain range, for example, a range of 15 to 20 μm, the allowable surface pressure gradually saturates, or tends to decrease slightly above 20 μm. Therefore, as an example, it can be understood that by setting the average value (φ1) of the predetermined domain to about 10 to 15 μm, a high allowable surface pressure of 3.5 MPa or more can be achieved.

[0048] 7(a), when a sliding resin composition that does not contain a carbon material is used, the friction coefficient (-) decreases and the allowable surface pressure (MPa) increases in relation to the average value (φ1) of domains of 10 μm or more derived from component (B), and both effects can be improved. That is, as can be seen from the characteristic curve in FIG. 7(a), when the average value (φ1) of a predetermined domain is within a predetermined range, for example, about 10 to 20 μm, the friction coefficient tends to become low.

[0049] Furthermore, it is preferable that the coefficient of friction of a molded article (sliding member) made using the sliding composition of the present invention be set to a value within the range of 0.1 to 0.65. The reason for this is that such a value improves sliding properties and more effectively prevents the generation of unpleasant sliding friction noise (squeaking noise) due to stick-slip. Therefore, as one example, the coefficient of friction of the molded article is preferably 0.65 or less, more preferably 0.4 or less, even more preferably 0.22 or less, and particularly preferably 0.2 or less.

[0050] Referring to FIG. 1(b), the relationship between the average value (φ1) of domains of 10 μm or more per unit area derived from component (B) and the allowable surface pressure (MPa) will be described for a sliding resin composition containing a carbon material. That is, FIG. 1(b) shows the average value (φ1) of a given domain in a sliding resin composition containing a carbon material on the horizontal axis, and the allowable surface pressure (MPa) on the vertical axis. As can be seen from the characteristic curve in FIG. 1(b), the allowable surface pressure increases as the average value (φ1) of the domain increases, but there is a slight tendency for this to gradually saturate. Therefore, by setting the average value (φ1) of the given domain to a value of 10 μm or more, a high allowable surface pressure of approximately 3 MPa or more can be achieved. As an example, it can be seen that by setting the average value (φ1) of the given domain to approximately 10 to 20 μm, a high allowable surface pressure of 3.5 MPa or more can be achieved.

[0051] However, as shown in Fig. 7(b), even when a sliding resin composition containing a carbon material is used, the relationship between the average value (φ1) of the predetermined domain and the friction coefficient (-) tends to be the opposite of the relationship with the allowable surface pressure (MPa). That is, as can be seen from the characteristic curve in Fig. 7(b), when the average value (φ1) of the predetermined domain is within a predetermined range (for example, 10 to 20 μm), the friction coefficient tends to be a low value equal to or less than a predetermined value.

[0052] (5) The average value (φ2) of at least five domains derived from component (B) in descending order is preferably set within the range of 10 to 130 μm. The average value (φ2) of at least five domains derived from component (B) per unit area is preferably set within the range of 10 to 130 μm. Specifically, the maximum particle size (φ2) of a given domain is targeted to confirm and evaluate the presence of relatively large domains, resulting in a predetermined non-uniform state. Controlling the maximum particle size (φ2) of a given domain reduces the coefficient of friction while increasing the allowable surface pressure, thereby effectively suppressing noise. Conversely, if the maximum particle size (φ2) of a given domain is less than 10 μm, the particles may be uniformly dispersed in the form of fine particles, making it difficult to effectively suppress noise. On the other hand, if the maximum particle size (φ2) of a given domain exceeds 130 μm, the surface smoothness of the molded product may be impaired, resulting in poor appearance and increased susceptibility to molding defects such as peeling. Therefore, the maximum particle size (φ2) of the predetermined domain is preferably 80 μm or less, and more preferably 30 μm or less. Furthermore, the maximum particle size (φ2) of the predetermined domain is preferably a value exceeding 10 μm in relation to the average particle size (φ1) of the predetermined domain. Note that, hereinafter, the maximum particle size (φ2) of the predetermined domain will be explained assuming that five points are selected in descending order of the size of the domain derived from component (B).

[0053] Here, referring to Fig. 2(a), the relationship between the average value (φ2) of five domains derived from component (B), in descending order of size, and the allowable surface pressure (MPa) will be described for the case where a sliding resin composition containing no carbon material is used. That is, Fig. 2(a) shows the maximum particle size (φ2) of a given domain in a sliding resin composition containing given blending components, plotted on the horizontal axis, and the allowable surface pressure (MPa) measured by the method shown in Example 1, etc., plotted on the vertical axis. As can be seen from the characteristic curve in Fig. 2(a), the allowable surface pressure increases as the maximum particle size (φ2) of the given domain increases, but gradually saturates. Furthermore, when the maximum particle size (φ2) of the given domain exceeds a given value, the allowable surface pressure tends to decrease.

[0054] Therefore, by making the maximum particle size (φ2) of the specified domain 10 μm or more, the allowable surface pressure can be set to approximately 3 MPa or more, and by making the maximum particle size (φ2) of the specified domain 20 μm or more, the allowable surface pressure can be set to 3.5 MPa or more. On the other hand, if the maximum particle size (φ2) of the specified domain is set to a value exceeding 130 μm, the surface condition of the molded product may deteriorate. Therefore, in order to obtain a high allowable surface pressure, it is preferable to adjust the maximum particle size (φ2) of the specified domain to a value at least within the range of 10 to 130 μm.

[0055] However, as shown in Fig. 8(a), when a sliding resin composition containing no carbon material is used, the relationship between the average value (φ2) of at least five domains derived from component (B) in descending order of size and the coefficient of friction (-) is the opposite of the relationship with the allowable surface pressure (MPa). That is, as can be seen from the characteristic curve in Fig. 8(a), when the maximum particle size (φ2) of a given domain is within a given range (for example, a value within a range of 10 to 130 μm), the coefficient of friction tends to be a low value below a given value.

[0056] 2(b), the relationship between the average value (φ2) of five domains derived from component (B) in descending order from largest to smallest and the allowable surface pressure (MPa) will be explained when a sliding resin composition containing a carbon material is used. That is, in FIG. 2(b), the horizontal axis shows the maximum particle size (φ2) of a given domain in a sliding resin composition containing a carbon material, and the vertical axis shows the allowable surface pressure (MPa). As can be seen from the characteristic curve in FIG. 2(b), the allowable surface pressure increases as the maximum particle size (φ2) of a given domain increases, but there is a tendency for this to gradually saturate.

[0057] Therefore, by setting the maximum particle size (φ2) of the predetermined domain to a value of 10 μm or more, the allowable surface pressure can be set to a value of approximately 3 MPa or more. On the other hand, if the maximum particle size (φ2) of the predetermined domain is set to a value exceeding 130 μm, the surface smoothness of the molded product may be impaired, the appearance may deteriorate, and molding defects such as peeling may become more likely to occur. As shown in Figure 3(b), when the domains derived from component (B) are dispersed in the form of fine particles, it can be understood that the five domains surrounded by the specified circles, in descending order of size, are almost the same as the other domains, i.e., are uniformly dispersed.

[0058] (6) Area Ratio (φ3) of Domains of 10 μm or More Derived from Component (B) Furthermore, it is preferable to set the area ratio (φ3) of domains of 10 μm or more in equivalent circle diameter derived from Component (B) per unit area to a value within the range of 0.5 to 20%. That is, the area ratio (φ3) of the predetermined domains is controlled to confirm and evaluate whether relatively large domains are dispersed unevenly to an appropriate degree. This reduces the friction coefficient while increasing the allowable surface pressure, thereby effectively suppressing the generation of abnormal noise. Conversely, if the area ratio (φ3) of the predetermined domains is less than 0.5%, the domains will be dispersed uniformly, making it difficult to effectively suppress the generation of abnormal noise. On the other hand, if the area ratio (φ3) of the predetermined domains exceeds 20%, the surface smoothness of the molded product will be impaired, resulting in poor appearance and increased susceptibility to molding defects such as peeling. Therefore, it is preferable that the area ratio (φ3) of the predetermined domain is set to a value within the range of 1 to 10%, and more preferably within the range of 1.5 to 5%.

[0059] Here, referring to FIG. 4( a), the relationship between the area ratio (φ3) of the predetermined domain and the allowable surface pressure (MPa) will be described for the case where a sliding resin composition containing no carbon material is used. That is, in FIG. 4( a), the horizontal axis represents the value of the area ratio (φ3) of the predetermined domain in a sliding resin composition containing predetermined blending components, and the vertical axis represents the value of the allowable surface pressure (MPa) measured by the method described in Example 1, etc. As can be seen from the characteristic curve in FIG. 4( a), the allowable surface pressure (MPa) increases as the area ratio (φ3) of the predetermined domain increases, but there is a tendency for this to gradually saturate. Conversely, when the area ratio (φ3) of the predetermined domain exceeds a predetermined value, there is a tendency for the allowable surface pressure to decrease. Therefore, by setting the area ratio (φ3) of the predetermined domain to a value between 0.5 and 5%, it becomes easy to achieve an allowable surface pressure of approximately 3 MPa or more.

[0060] However, as shown in Fig. 9(a), when a sliding resin composition containing no carbon material is used, the relationship between the area ratio of the predetermined domain (φ3) and the coefficient of friction (-) is the opposite of the relationship with the allowable surface pressure (MPa). That is, as can be seen from the characteristic curve in Fig. 9(a), when the area ratio of the predetermined domain (φ3) is in a predetermined range (for example, 1.5 to 5%), the coefficient of friction tends to be a low value equal to or lower than a predetermined value.

[0061] (7) Relationship between the average value (φ1) of domains of 10 μm or larger derived from component (B) and the area fraction (φ3) of domains of 10 μm or larger derived from component (B) Next, referring to FIG. 5(b), the relationship between the average value (φ1) of domains of 10 μm or larger derived from component (B) and the area fraction (φ3) of domains of 10 μm or larger derived from component (B) in a predetermined sliding agent composition (without blending of a carbon material) will be explained. The horizontal axis represents the average value (φ1) of the predetermined domains, and the vertical axis represents the area fraction (φ3) of the predetermined domains. As shown by the characteristic curve in FIG. 5(b), there is a tendency that the area fraction (φ3) of the predetermined domains increases as the average value (φ1) of the predetermined domains increases. Therefore, by controlling the magnitude of the average value (φ1) of the predetermined domains, the area ratio (φ3) of the predetermined domains can also be controlled within a desired range, and as a result, it can be said that the allowable surface pressure can also be controlled within a desired range, as shown in Figures 4(a) and 4(b). Note that Figure 6(b) shows the relationship between the average value (φ1) of the predetermined domains and the area ratio (φ3) of the predetermined domains in a predetermined sliding agent composition (containing a carbon material), and the tendency is substantially the same as that of the characteristic curve in Figure 5(b).

[0062] (8)-1 Relationship between the average value (φ2) of five domains derived from component (B), arranged in descending order of size, and the average value (φ1) of domains of 10 μm or larger derived from component (B). Next, referring to FIG. 5(a), the relationship between the maximum particle size (φ2) of a given domain and the average value (φ1) of the given domain in a given sliding agent composition (without a carbon material) will be explained. The horizontal axis represents the maximum particle size (φ2) of the given domain, and the vertical axis represents the average value (φ1) of the given domain. As shown in the characteristic curve in FIG. 5(a), as the maximum particle size (φ2) of the given domain increases, the average value (φ1) of the given domain also increases rapidly, and then tends to saturate rapidly. Therefore, by controlling the size of the maximum particle size (φ2) of the given domain, the average value (φ1) of the given domain can be controlled within a desired range. Consequently, as shown in FIGS. 1(a) and 1(b), it can be said that the allowable surface pressure can also be controlled within a desired range. FIG. 6(a) shows the relationship between the average value (φ1) of the predetermined domains and the area ratio (φ3) of the predetermined domains in a predetermined sliding agent composition (containing a carbon material), and the tendency is substantially the same as that of the characteristic curve in FIG. 5(a).

[0063] (8)-2 Relationship between the average value (φ2) of at least five domains derived from component (B), arranged in descending order of size, and the area ratio (φ3) of domains of 10 μm or larger derived from component (B). Next, referring to FIG. 5(c), the relationship between the maximum particle size (φ2) of the predetermined domain and the area ratio (φ3) of the predetermined domain in a predetermined sliding agent composition (without a carbon material) will be explained. The horizontal axis represents the maximum particle size (φ2) of the predetermined domain, and the vertical axis represents the area ratio (φ3) of the predetermined domain. As shown by the characteristic curve in FIG. 5(c), as the maximum particle size (φ2) of the predetermined domain increases, the area ratio (φ3) of the predetermined domain also increases rapidly, and then gradually saturates. Therefore, by controlling the size of the maximum particle size (φ2) of the predetermined domain, the area ratio (φ3) of the predetermined domain can be controlled within a desired range. Consequently, as shown in FIGS. 4(a) and 4(b), it can be said that the allowable surface pressure can also be controlled within a desired range. FIG. 6(c) shows the relationship between the maximum particle size (φ2) of the predetermined domain and the area ratio (φ3) of the predetermined domain in a predetermined sliding agent composition (containing a carbon material), and the tendency is substantially the same as that of the characteristic curve in FIG. 5(c).

[0064] (9) The area ratio (φ4) of domains of 10 μm or more derived from component (B) per unit area of ​​total particle. It is also preferable to set the area ratio (φ4) of domains of 10 μm or more derived from component (B) per unit area of ​​total particle. The purpose of controlling the area ratio (φ4) of the specified domains is to confirm and evaluate whether both domains of 10 μm or more and domains of less than 10 μm exist at a certain ratio, i.e., whether the domains are in a non-uniform state. This reduces the coefficient of friction while increasing the allowable surface pressure, thereby effectively suppressing noise. Conversely, if the area ratio (φ4) of the specified domains is less than 5%, the result will be a uniform dispersion, making it difficult to effectively suppress noise. On the other hand, if the area ratio (φ4) of the specified domains is greater than 95%, the surface smoothness of the molded product will be impaired, resulting in poor appearance and increased susceptibility to molding defects such as peeling. Therefore, it is more preferable to set the area ratio (φ4) of the predetermined domain to a value within the range of 10 to 80%, and even more preferable to set it to a value within the range of 20 to 60%. Note that it is known that particles of a size that are considered to account for approximately 1% or less of the total particle area and cannot be recognized by image analysis have almost no effect on the calculation of φ1 to φ4 and can be ignored.

[0065] 3. (C) Lubricating Oil (1) Types The sliding resin composition preferably contains, as component (C), a lubricating oil that is liquid at room temperature or that becomes liquid upon molding and heating. Examples of lubricating oils that are liquid at room temperature include paraffinic and naphthenic mineral oils such as spindle oil, refrigeration oil, dynamo oil, turbine oil, machine oil, cylinder oil, and gear oil; animal oils such as whale oil; vegetable oils such as castor oil and jojoba oil; and synthetic oils such as esters, polyglycols, polyphenyl ethers, silicones, and halocarbons. Examples of lubricating oils that become liquid upon molding and heating include natural waxes such as montan wax and carnauba wax, hydrocarbon waxes, and waxes derived from higher fatty acids.

[0066] That is, examples of hydrocarbon waxes include at least one of paraffin waxes having approximately 24 or more carbon atoms, olefin waxes having approximately 26 or more carbon atoms, alkylbenzene waxes having approximately 28 or more carbon atoms, and microcrystalline waxes. Examples of higher fatty acids include at least one of higher saturated fatty acids having approximately 12 or more carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, cerotic acid, and montanic acid, and unsaturated fatty acids having 18 or more carbon atoms, such as oleic acid, linoleic acid, linolenic acid, elaidic acid, octadecenoic acid, arachidonic acid, cadreic acid, erucic acid, and parinaric acid. Examples of waxes obtained by deriving higher fatty acids include higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

[0067] (2) Amount of Blend Furthermore, it is preferable to set the blend amount of the lubricating oil agent (Component (C)) to a value within the range of 0.1 to 10 parts by weight per 100 parts by weight of Component (A). The reason for this is that if the blend amount of Component (C) is less than 0.1 part by weight, the effect of improving sliding properties may be insufficient. On the other hand, if the blend amount of Component (C) is more than 10 parts by weight, the mechanical properties, surface appearance, and moldability of the molded sliding member may be reduced. Therefore, it is more preferable to set the blend amount of the lubricating oil agent (Component (C)) to a value within the range of 0.3 to 5 parts by weight per 100 parts by weight of Component (A), and even more preferably within the range of 0.5 to 3 parts by weight.

[0068] 4. (D) Polyolefin Resin (1) Types In the sliding resin composition, it is preferable to blend a known polyolefin resin as component (D), excluding the olefin-based elastomer corresponding to component (B). Blending such a polyolefin resin may adjust the sliding properties of the sliding resin member and further suppress the generation of sliding noise. Therefore, examples of such (D) polyolefin resins include at least one of polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), and polybutylene (PB-1). Furthermore, the polyolefin resin is preferably a modified polyolefin resin to which a reactive functional group has been added. Examples of reactive functional groups include a carboxy group, an acid anhydride group, an epoxy group, an oxazoline group, an amino group, and an isocyanate group. From the viewpoint of ensuring a higher allowable surface pressure through a synergistic effect with component (B), it is preferable to use maleic anhydride-modified polyethylene. The polyolefin resin (D) may also be a copolymer containing a structural unit derived from ethylene and a structural unit having a reactive functional group. Examples of the structural unit having a reactive functional group include glycidyl methacrylate (GMA) having an epoxy group. Specific examples include ethylene-glycidyl methacrylate copolymer, ethylene-vinyl acetate-glycidyl methacrylate copolymer, and ethylene-methyl acrylate-glycidyl methacrylate copolymer.

[0069] (2) Density and Melt Flow Rate The density of the polyolefin resin is not particularly limited, but is usually 860 to 930 kg / m 3 It is preferable to set the value within the range of 900 to 930 kg / m 3 It is more preferable to set the value within the range of 910 to 930 kg / m 3The melt flow rate (MFR) of the polyolefin resin is not particularly limited either, but is usually preferably in the range of 2 to 100 g / 10 min, and more preferably in the range of 25 to 50 g / 10 min.

[0070] (3) Amount of Compounding Furthermore, it is preferable to set the amount of compounding (D) polyolefin resin to a value within the range of 0.01 to 10 parts by weight per 100 parts by weight of component (A). The reason for this is that if the amount of compounding (D) component is less than 0.01 part by weight, the effect of improving sliding properties may be insufficient. On the other hand, if the amount of compounding (D) component is more than 10 parts by weight, the mechanical properties and surface appearance of the molded sliding member may be deteriorated. Therefore, it is more preferable to set the amount of compounding (D) polyolefin resin to a value within the range of 0.1 to 5 parts by weight per 100 parts by weight of component (A), and even more preferably within the range of 0.5 to 3 parts by weight.

[0071] (4) Commercially Available Products Typical examples of commercially available polyolefin resins include ethylene-glycidyl methacrylate copolymers such as Bondfast E manufactured by Sumitomo Chemical Co., Ltd., maleic anhydride-modified low-density polyethylene such as Admer NR106 manufactured by Mitsui Chemicals, and maleic anhydride-modified ultra-high molecular weight polyethylene such as Lubmer LY1040 manufactured by Mitsui Chemicals, Ltd.

[0072] 5. (E) Carbon Material (1) Type It is preferable to blend a predetermined amount of a carbon material as component (E) with the main resin (A). The type of carbon material for component (E) is not particularly limited, but is preferably at least one of natural or artificial graphite, carbon black such as furnace black, acetylene black, thermal black, or channel black, and carbon materials (carbon fibers) such as carbon nanofibers or carbon nanotubes. By blending at least one of these carbon materials, an excellent coloring effect can be achieved even with a relatively small amount. Furthermore, a carbon material can function as a carrier for absorbing and retaining lubricating oil, further improving the durability, lubricity, heat resistance, etc. of the sliding member.

[0073] Furthermore, it is preferable that the primary particle size of the carbon material of component (E) is less than about 200 nm. The reason for this is that by incorporating a carbon material having such a primary particle size, it becomes easier to function as a carrier for absorbing and retaining the lubricating oil agent described below, which may in turn make it easier to suppress the generation of squeaking noises and the like. Therefore, it is more preferable that the primary particle size of component (E) be 5 nm to 150 nm, and even more preferably 10 nm to 100 nm.

[0074] Furthermore, it is preferable that the DBP oil absorption of the carbon material of component (E) is 100 ml / 100 g or more. The reason for this is that by blending a carbon material having such a DBP oil absorption, it is possible to absorb and retain a larger amount of lubricant, which may further facilitate suppression of squeaking noises and the like. Therefore, it is more preferable that the DBP oil absorption of component (E) is 200 ml / 100 g or more, and even more preferable that it is 300 ml / 100 g or more.

[0075] More specifically, the carbon material is preferably one having a hollow structure and a kind of porous structure, and more preferably one having a moderate chain structure. Examples of carbon materials having such a structure include "Carbon ECP (trade name)" and "Ketjenblack EC-600JD (trade name)" manufactured by Lion Specialty Chemicals Co., Ltd.

[0076] (2) Amount of Blend The amount of the carbon material blended varies depending on the application of the sliding member, but is usually preferably 0.01 to 10 parts by weight or less per 100 parts by weight of component (A). The reason for this is that by setting the amount of carbon material blended within a predetermined range, it may be possible to further improve the durability, lubricity, heat resistance, etc. of the sliding member. Therefore, although the amount of the carbon material blended varies depending on the application of the sliding member, it is usually more preferably 0.5 parts by weight or less per 100 parts by weight of component (A), even more preferably 0.05 to 0.4 parts by weight, and particularly preferably 0.08 to 0.3 parts by weight.

[0077] 6. Additive 1 It is also preferable to add other additives such as solid lubricants (e.g., molybdenum disulfide, polytetrafluoroethylene, etc.), fibrous materials (e.g., glass fiber, carbon fiber, aramid fiber, potassium titanate fiber and its whiskers, etc.), and inorganic fillers (e.g., glass powder, talc, clay, calcium carbonate, zinc oxide, etc.). In other words, it is also preferable to incorporate such solid lubricants, fibrous materials, inorganic fillers, etc., to further improve the wear resistance, durability, heat resistance, etc., of the sliding member. Therefore, the amount of such solid lubricants, etc., added, depending on the application of the sliding member, is generally set to a value within the range of 0.01 to 10 parts by weight, more preferably within the range of 0.1 to 5 parts by weight, and even more preferably within the range of 1 to 3 parts by weight, per 100 parts by weight of component (A).

[0078] 7. Additive 2 It is also preferable to add at least one of various other stabilizers, such as an ultraviolet absorber, an antioxidant, or a heat stabilizer, to further improve the light stability, durability, heat resistance, etc. of the sliding member. Therefore, the amount of such stabilizer to be added will vary depending on the application of the sliding member, but is usually set to a value within the range of 0.001 to 1 part by weight, more preferably 0.005 to 0.5 parts by weight, and even more preferably 0.008 to 0.2 parts by weight, per 100 parts by weight of component (A).

[0079] Furthermore, depending on the intended use of the sliding resin composition, it is also preferable to incorporate at least one functional additive such as various colorants (excluding carbon materials), release agents, antistatic agents, surfactants, etc. The amount of such functional additive to be incorporated varies depending on the type of additive and the intended use of the sliding member, but is generally set to a value within a range of preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and even more preferably 0.1 to 1 part by weight, per 100 parts by weight of component (A).

[0080] 8. Manufacturing Method The sliding resin composition can be easily prepared by a known method commonly used for preparing conventional resin compositions. For example, at least the essential components (A) and (B), the optional components (C) to (E), and other additives are weighed in predetermined amounts and mixed until homogeneous in a mixer such as a Henschel mixer, super mixer, ball mill, or tumbler mixer to produce a mixture. Next, the resulting mixture is fed into a single- or twin-screw extruder, typically an extruder, and melt-kneaded at a predetermined temperature and pressure to form a string-like molded product, which is then cut into pellets, according to a known manufacturing method.

[0081] That is, the sliding resin composition has good molding processability, such as good bite into the screw of a molding machine, and a sliding member formed by molding the sliding resin composition can be easily produced by a conventional injection molding machine or extrusion molding machine. The obtained sliding member has significantly improved load resistance without impairing mechanical properties, is prevented from generating abnormal noises such as creaking noises during sliding friction with a mating material, and can significantly improve sliding properties including low friction and wear resistance.

[0082] [Second Embodiment] The second embodiment is a sliding resin member comprising, as its constituent components, a sliding resin composition containing the following components (A) and (B): In the sliding resin member, domains of 10 μm or more derived from at least the component (B) are non-uniformly dispersed in the component (A). The sliding resin member is characterized in that domains derived from the component (B) having an equivalent circle diameter of 10 μm or more are selected per unit area of ​​any cross section, and the average equivalent circle diameter (φ1) of the selected domains is set to a value within the range of 10 to 30 μm. The sliding resin member comprises: (A) 100 parts by weight of at least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin; and (B) 1 to 70 parts by weight of an olefin-based elastomer, a styrene-based elastomer, or either one of them. Hereinafter, with reference to the drawings as appropriate, the sliding member of the second embodiment will be specifically described, focusing on differences from the sliding resin composition of the first embodiment.

[0083] 1. Sliding Resin Composition Basically, the sliding resin composition of the second embodiment can be the same as the sliding resin composition of the first embodiment, and therefore, a repeated explanation will be omitted here.

[0084] 2. Sliding Members (1) Types The form of the sliding member obtained from the sliding resin composition by injection molding or the like is not particularly limited, and various modifications are possible. For example, a typical sliding member is a sliding bearing, but it is preferably a cylindrical bearing that receives a load on its inner circumferential surface and has the same thickness as its end faces, or a flanged bearing that receives a load on its inner circumferential surface and its end faces. At least one such sliding bearing may be provided, or multiple sliding bearings may be provided.

[0085] (2) Sliding Characteristics Various sliding characteristics of the sliding member made of the sliding resin composition can be evaluated by evaluating noise generation, friction coefficient, allowable surface pressure, etc. in accordance with Evaluations 4 to 6 as shown in Example 1.

[0086] 3. Manufacturing Method There are no particular limitations on the method for manufacturing a sliding member derived from a sliding resin composition, but typically, it is preferable to use an injection molding method.

[0087] (Injection Molding Method) That is, according to the injection molding method, a predetermined sliding member can be manufactured by the following steps 1) to 5), which is one example. 1) Prepare an injection molding device. 2) Put the sliding resin composition, which is molding material pellets, into a hopper or the like of the injection molding device. 3) Use the heating device of the injection molding device to melt the sliding resin composition. 4) Use the injection molding device to inject the molten sliding resin composition into a predetermined mold. 5) After cooling, remove the predetermined sliding member.

[0088] <Preparation of Blended Components> In each of the Examples and Comparative Examples, the following raw materials were prepared and used as blended components.

[0089] Component (A): POM, etc. (A1) As the component (A), a polyacetal resin (copolymer) [Duracon M90-44 (trade name) manufactured by Polyplastics Co., Ltd.] was prepared. (A2) As the component (A), a polybutylene terephthalate resin [Toraycon 1401X06 (trade name) manufactured by Toray Industries, Inc.] was prepared. (A3) As the component (A), a polyamide resin (nylon 66) [Leona 1402S (trade name) manufactured by Asahi Kasei Corporation] was prepared. (A4) As the component (A), a polycarbonate resin [Iupilon S-2000 (trade name) manufactured by Mitsubishi Engineering Plastics Corporation] was prepared.

[0090] Component (B): Olefin-based elastomer and styrene-based elastomer (B1) An EPDM having an ethylene content of 65% by weight and 5-ethylidene-2-norbornene (ENB) as the diene component (diene content 4.6% by weight) and a Mooney viscosity at 125°C of ML(1+4) of 61 ("Mitsui EPT3092PM (trade name)" manufactured by Mitsui Chemicals, Inc.) was prepared. (B2) An EPDM having an ethylene content of 67% by weight and 5-ethylidene-2-norbornene (ENB) as the diene component (diene content 4.5% by weight) and a Mooney viscosity at 125°C of ML(1+4) of 58 ("EP57C (trade name)" manufactured by ENEOS Materials Corporation) was prepared. (B3) An olefin-ethylene-butylene-olefin block polymer (CEBC) having a melt flow rate of less than 0.1 g / 10 min at 230°C under a load of 2.16 kg (DYNARON 6201B (trade name) manufactured by ENEOS Materials Corporation) was prepared. (B4) An EPM (Mitsui EPT0045 (trade name) manufactured by Mitsui Chemicals, Inc.) having an ethylene content of 51 wt% and a Mooney viscosity at 100°C of 40 (ML(1+4)) was prepared. (B5) An EPDM (Mitsui EPT3110M (trade name) manufactured by Mitsui Chemicals, Inc.) having an ethylene content of 56 wt% and a diene component of 5-ethylidene-2-norbornene (ENB) (diene content 5.0 wt%) and a Mooney viscosity at 125°C of 78 (ML(1+4)) was prepared.

[0091] (B6) An EPDM having an ethylene content of 72% by weight, 5-ethylidene-2-norbornene (ENB) as the diene component (diene content: 3.6% by weight), and a Mooney viscosity ML(1+4) at 100°C of 15 ("Mitsui EPT-X-3012P (trade name)" manufactured by Mitsui Chemicals, Inc.) was prepared.

[0092] (B7) An EPDM ["Mitsui EPT3070 (trade name)" manufactured by Mitsui Chemicals, Inc.] having an ethylene content of 58% by weight, 5-ethylidene-2-norbornene (ENB) as the diene component (diene content 4.7% by weight), and a Mooney viscosity ML(1+4) at 125°C of 47 was prepared.

[0093] (B8) Styrene-butadiene rubber (SBR) containing 25% by weight of styrene and having a Mooney viscosity ML(1+4) of 78 at 100°C (manufactured by Asahi Kasei Corporation, "Tufden 2110R (trade name)") was prepared.

[0094] (B9) A styrene-ethylene-butylene-styrene copolymer (SEBS) [DYNARON 9901P (trade name) manufactured by ENEOS Materials Corporation] containing 35% by weight of styrene and having a melt flow rate of 3.3 g / 10 min at a temperature of 230°C and a load of 2.16 kg was prepared.

[0095] (B10) An ethylene-vinyl acetate copolymer (EVA) containing 46% by weight of vinyl acetate and having a melt flow rate of 2.5 g / 10 min at a temperature of 190°C and a load of 2.16 kg (EVAFLEX EV45LX (trade name) manufactured by Mitsui Dow Polychemicals) was prepared.

[0096] (B11) An ethylene-1-butene copolymer (EBR) ("Excellen VL100" manufactured by Sumitomo Chemical Co., Ltd.) having a melt flow rate of 0.8 g / 10 min at a temperature of 190° C. and a load of 2.16 kg was prepared.

[0097] (B12) An ethylene-vinyl acetate copolymer (EVA) containing 46% by weight of vinyl acetate and having a melt flow rate of 100 g / 10 min at a temperature of 190°C and a load of 2.16 kg (EVAFLEX EV45X (trade name) manufactured by Mitsui Dow Polychemicals) was prepared.

[0098] (B13) An ethylene-ethyl acrylate copolymer (EEA) [ENEOS NUC Corporation's "NUC6675"] containing 25% by weight of ethyl acrylate and having a melt flow rate of 20 g / 10 min at a temperature of 190° C. and a load of 2.16 kg was prepared.

[0099] Component (C): Lubricating Oil (C1) Paraffin oil (MORESCO White P-350P, manufactured by MORESCO Corporation) was prepared. (C2) Hydrocarbon-based synthetic oil (ethylene-α-olefin oligomer) (Mitsui Chemicals, Inc., Lucant) was prepared.

[0100] Component (D): Polyolefin Resin (D1) Maleic anhydride-modified low-density polyethylene (Admer NR106, manufactured by Mitsui Chemicals) was prepared. (D2) Ethylene-glycidyl methacrylate copolymer (Bondfast E, manufactured by Sumitomo Chemical) was prepared.

[0101] (E) Component: Carbon material (E1) Carbon black (primary particle size: 34 nm, manufactured by Lion Specialty Chemicals, Ketjenblack EC600JD) was prepared. (E2) Amorphous graphite powder (average particle size: 5 μm, manufactured by Nippon Graphite, P#1) was prepared.

[0102] Example 1 1. Preparation of Sliding Resin Composition and Sliding Member (Molded Article) A high-speed mixer was charged with 100 parts by weight of the polyacetal resin (A1) as the component (A), 5.3 parts by weight of the olefin elastomer (B1) as the component (B), and 2.2 parts by weight of the polyolefin resin (D1) as the component (D), and the resulting mixture was stirred in the high-speed mixer to obtain a sliding resin composition.

[0103] The obtained sliding resin composition was fed to a twin-screw extruder (Thermo Fisher Process 11, screw diameter 11 mm) and melt-kneaded under conditions of (200°C, 300 rpm) to form a string-like molded product, which was then cut with a pelletizer to prepare pellet material. Next, this pellet material was injection-molded using a screw-type injection molding machine (Sumitomo Heavy Industries, Ltd., SE50-DUZ, screw diameter 25 mm) to obtain a plate-like sliding member measuring 30 mm square and 3 mm thick.

[0104] 2. Evaluation of Sliding Resin Compositions and Sliding Members (Molded Articles) Made Therefrom (1) Evaluation 1 (Average Value of Domains of 10 μm or More: φ1) Test pieces of plate-shaped sliding members were cut to an arbitrary size, embedded in epoxy resin, and polished to prepare observation samples. Observation images were then obtained at 100 to 500 magnifications using a scanning electron microscope (SEM). Specifically, the observation images shown in FIGS. 12(a) and 12(b) (Examples 12 and 15) were obtained. Next, all domains (dispersed state) of 10 μm or more per unit area derived from component (B) were selected using image analysis (image analysis software ["WinROOF2018" manufactured by Mitani Shoji Co., Ltd.]; the same applies hereinafter), and the average value of the specific domains was calculated. Evaluation was performed according to the following criteria: ⊚: The average value (φ1) of the specific domains was within the range of 10 to 15 μm. ◯: The average value (φ1) of a predetermined domain is a value in the range of more than 15 μm to 20 μm. △: The average value (φ1) of a predetermined domain is a value in the range of more than 20 μm to 30 μm. ×: There are no particles of 10 μm or more, or the average value (φ1) of a predetermined domain is a value exceeding 30 μm.

[0105] (2) Evaluation 2 (Maximum particle size of a predetermined domain: φ2) The average value of the domains (dispersion state) of component (B) per unit area in any cross section of the test piece was measured using image analysis, and five domains were selected in descending order of size. The average value (φ2) was then calculated and evaluated according to the following criteria: ◎: The maximum particle size of the predetermined domain was in the range of 10 to 30 μm. ○: The maximum particle size of the predetermined domain was in the range of more than 30 μm to 80 μm. △: The maximum particle size of the predetermined domain was in the range of more than 80 μm to 130 μm. ×: The maximum particle size of the predetermined domain was less than 10 μm or more than 130 μm.

[0106] (3) Evaluation 3 (area ratio of domains of 10 μm or more: φ3) Using image analysis, the area ratio of domains of 10 μm or more derived from component (B) was calculated in an arbitrary cross section of the test piece, where the unit area was taken as 100%, and evaluated according to the following criteria. ◎: The area ratio of the specified domain was a value in the range of 1.5 to 5%. ◯: The area ratio of the specified domain was a value of 1 to less than 1.5%, or a value in the range of more than 5% to 10%. △: The area ratio of the specified domain was a value of 0.5 to less than 1%, or a value in the range of more than 10% to 20%. ×: The area ratio of the specified domain was a value less than 0.5% or a value greater than 20%.

[0107] (4) Evaluation 4 (Generation of Abnormal Noise) The generation of abnormal noise was evaluated under the following sliding conditions. Movement type: One-way thrust rotation Surface pressure: 13 MPa Speed: 0.05 m / s Counterpart material (when the main resin is POM): POM cylinder (φ25.6 × φ20 × L15) Here, as the counterpart material, PBT was used when the main resin was PBT, PA66 was used when the main resin was PA66, and PC was used when the main resin was PC. Lubrication conditions: No lubrication Sliding time: 30 s ◎: No abnormal noise was heard at all. ○: Almost no abnormal noise was heard. △: Some abnormal noise was heard. ×: Significant abnormal noise was heard.

[0108] (5) Evaluation 5 (Coefficient of Friction) The coefficient of friction on the surface of the test piece was measured under the following test conditions, and the average coefficient of friction was calculated. Movement type: One-way thrust rotation Surface pressure: 1 MPa Speed: 0.05 m / s Time: 3 minutes Counterpart material (when the main resin is POM): POM cylinder (φ25.6 × φ20 × L15) Here, as the counterpart material, when the main resin is PBT, PBT was used, when the main resin is PA66, PA66 was used, and when the main resin is PC, PC was used. Lubrication conditions: No lubrication

[0109] (6) Evaluation 6 (Allowable Surface Pressure) The allowable surface pressure on the surface of the test piece was measured under the following test conditions, and the allowable surface pressure was calculated. Movement type: Thrust unidirectional rotation Surface pressure: 1 MPa + 0.5 MPa (every 3 minutes) Speed: 0.5 m / s Counterpart material (when the main resin is POM): POM cylinder (φ25.6 × φ20 × L15) Here, as the counterpart material, PBT was used when the main resin was PBT, PA66 was used when the main resin was PA66, and PC was used when the main resin was PC. Lubrication conditions: No lubrication Test stop condition: Occurrence of abnormal noise (10 seconds or more)

[0110] (7) Evaluation 7 (Evaluation of Surface Appearance) The surface appearance of the plate-like sliding member was evaluated as follows. Molding defects include surface irregularities, peeling, flow marks, silver streaks, etc. ○: No molding defects occurred. ×: Molding defects occurred.

[0111] In Examples 2 to 23, sliding resin compositions were prepared using the components shown in Table 1, and plate-shaped sliding members serving as test pieces were prepared and evaluated in the same manner as in Example 1. The results obtained are shown in Table 2.

[0112] For Example 5, Fig. 10 shows the relationship between the circle-equivalent diameter (µm) of the domains derived from component (B), measured by image analysis, and the relative frequency (%) as an index of particle size distribution. That is, in Fig. 10, the horizontal axis represents the circle-equivalent diameter (µm) of the domains derived from component (B), and the vertical axis represents the relative frequency (%). More specifically, when the horizontal axis of the domain's equivalent circle diameter is 5 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 0 μm or more and less than 5 μm; when the horizontal axis is 10 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 5 μm or more and less than 10 μm; when the horizontal axis is 15 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 10 μm or more and less than 15 μm; when the horizontal axis is 20 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 15 μm or more and less than 20 μm; when the horizontal axis is 25 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 20 μm or more and less than 25 μm; and when the horizontal axis is 30 μm, it corresponds to the total relative frequency (%) of domains having an equivalent circle diameter of 25 μm or more and less than 30 μm. Thus, in the case of Example 5, for example, the relative frequency of domains with an equivalent circle diameter of less than 5 μm was 98.5%, the relative frequency of domains of 5 μm or more but less than 10 μm was 1.2%, and the relative frequency of domains of 10 μm or more was less than 0.3%. On the other hand, since the area fraction φ4 of the predetermined domains was 24%, it is inferred that domains with an equivalent circle diameter of 10 μm or more have a high area fraction of the predetermined domains per unit area of ​​the total particle, while domains with an equivalent circle diameter of less than 10 μm have a low area fraction, and therefore it is understood that an inhomogeneous dispersion state is formed overall. Furthermore, in Examples 2 to 23, as well as in the aforementioned Example 1, a similar tendency was confirmed between the equivalent circle diameter (μm) of the domains derived from component (B) and the relative frequency (%). That is, if a particle size distribution showing the relationship between the equivalent circle diameter (µm) of the domains derived from component (B) and the relative frequency (%) as shown in Fig. 10 is obtained, it can be recognized that the domains derived from component (B) are in a non-uniform state.

[0113] Comparative Example 1 In Comparative Example 1, a sliding resin composition was prepared and a resin sliding part was prepared and evaluated in the same manner as in Example 1, except that 5.3 parts by weight of EPDM (B6) ["Mitsui EPT-X-3012P" manufactured by Mitsui Chemicals, Inc.] having an ethylene content of 72% by weight, ENB as the diene component (diene content 3.6% by weight), and a Mooney viscosity ML(1+4) at 100°C of 15 was used as component (B) instead of the olefin-based elastomer of Example 1. However, in Comparative Example 1, no domains of 10 μm or more per unit area derived from component (B) were observed, and therefore the value of φ1 could not be measured.

[0114] In Comparative Example 2, instead of the olefin-based elastomer of Example 1, no component (B) was blended at all, and 7.5 parts by weight of carbon black (E1) (average particle size: 2.5 μm, natural graphite), a carbon material, was used as component (E), but a sliding resin composition was prepared and a resin sliding part was prepared and evaluated in the same manner as in Example 1. However, in Comparative Example 2, no domains of 10 μm or more per unit area derived from component (B) were observed.

[0115] In Comparative Example 3, 5.4 parts by weight of EPDM (B6) was used instead of the olefin-based elastomer in Example 1, and 2.2 parts by weight of carbon black (E1) was used as component (E). Except for this, a sliding resin composition was prepared and a resin sliding part was prepared and evaluated in the same manner as in Example 1. However, in Comparative Example 3, no domains of 10 μm or more per unit area derived from component (B) were observed.

[0116] For Comparative Example 3, FIG. 11 shows the relationship between the circle-equivalent diameter (μm) of domains derived from component (B), measured by image analysis, and the relative frequency (%) as an index of particle size distribution. As in FIG. 10 , the horizontal axis of FIG. 11 shows the circle-equivalent diameter (μm) of domains derived from component (B) at 5 μm intervals, and the vertical axis shows the relative frequency (%). Therefore, in the case of Comparative Example 3, when the circle-equivalent diameter of the domains is in the range of, for example, 5 μm to 20 μm, the total relative frequency of domains less than 5 μm is 100%. However, as the circle-equivalent diameter of the domains increases, the total relative frequency (%) rapidly decreases, and when the circle-equivalent diameter of the domains is 5 μm or more, it can be seen that the total relative frequency (%) of the domains decreases to 0%. Furthermore, a similar tendency was confirmed in Comparative Example 1 between the circle-equivalent diameter (μm) of domains derived from component (B) and the relative frequency (%). That is, if a particle size distribution showing the relationship between the equivalent circle diameter (µm) of the domains derived from the component (B) and the relative frequency (%) as shown in Fig. 11 is obtained, it can be recognized that the domains derived from the component (B) are in a uniform state.

[0117] Comparative Examples 4 to 7 In Comparative Examples 4 to 7, sliding resin compositions were prepared in the same manner as in Example 1, except that the blending components shown in Table 1 were used, and plate-shaped sliding members serving as test pieces were also prepared and evaluated.

[0118]

[0119]

[0120] As described above in detail, the sliding resin composition of the present invention comprises a resin as the main component (A) and a predetermined amount of an olefin-based elastomer or the like as the component (B), which are dispersed in a predetermined non-uniform state to form domains of a predetermined structure. Therefore, when a sliding member is formed from the composition, the occurrence of abnormal noise (squeaking noise) can be significantly reduced. That is, when the components are dispersed in a predetermined non-uniform state to form a sliding resin composition and processed into a predetermined sliding member, the sliding member has a friction coefficient and wear rate below predetermined values, exhibits good sliding properties over a long period of time, and minimizes the occurrence of squeaking noise due to stick-slip. Therefore, the sliding resin composition of the present invention can be used in a wide range of fields as various sliding members, and is particularly suitable for use when processed into sliding members such as bearings for automotive parts, electrical and electronic products, office equipment, and the like, which are always expected to be used under dry conditions.

Claims

1. A sliding resin composition comprising at least the following components (A) and (B), wherein domains having an equivalent circle diameter of 10 μm or more derived from component (B) that are non-uniformly dispersed in component (A) per unit area are selected, and the average value of the equivalent circle diameters (φ1) of the selected domains is set to a value within the range of 10 to 30 μm: (A) 100 parts by weight of at least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin; (B) 1 to 70 parts by weight of an olefin-based elastomer and / or a styrene-based elastomer; 2. The sliding resin composition according to claim 1, characterized in that at least five domains, n1 to n5, are selected per unit area from the domains derived from component (B) in descending order of equivalent circle diameter, and the average value (φ2) of the equivalent circle diameters of the selected domains is set to a value within the range of 10 to 130 μm.

3. The sliding resin composition according to claim 1, characterized in that the area ratio (φ3) of domains derived from component (B) and having an equivalent circle diameter of 10 μm or more per unit area is set to a value within the range of 0.5 to 20%.

4. The sliding resin composition according to claim 1, further comprising a lubricant as component (C), the amount of component (C) being within the range of 0.1 to 10 parts by weight per 100 parts by weight of component (A).

5. The sliding resin composition according to claim 1, further comprising a carbon material as component (E), wherein the amount of component (E) blended is within the range of 0.01 to 10 parts by weight per 100 parts by weight of component (A).

6. The sliding resin composition according to claim 1, wherein the melt flow rate of component (A) is set to a value within the range of 3 to 100 g / 10 min.

7. The sliding resin composition according to claim 1, wherein component (B) is at least one resin selected from the group consisting of ethylene-propylene copolymer (EPM), ethylene-propylene-diene copolymer (EPDM), ethylene-1-butene copolymer (EBR), ethylene-vinyl acetate copolymer (EVA), olefin-ethylenebutylene-olefin block copolymer (CEBC), styrene-butadiene copolymer (SBR), and styrene-ethylenebutylene-styrene copolymer (SEBS), and wherein the resin has a Mooney viscosity ML(1+4) at 100°C of 40 to 110, a Mooney viscosity ML(1+4) at 125°C of 20 to 80, or a melt flow rate (190°C, 2.16 kg) of less than 3 g / 10 min.

8. A sliding resin member comprising as its constituent components a sliding resin composition comprising the following components (A) and (B), in which domains derived from at least component (B) and having an equivalent circle diameter of 10 μm or more are dispersed non-uniformly in component (A), wherein domains derived from component (B) and having an equivalent circle diameter of 10 μm or more per unit area are selected, and the average value (φ1) of the equivalent circle diameters of the selected domains is set to a value within the range of 10 to 30 μm: (A) At least one main resin selected from the group consisting of polyacetal resin, polyamide resin, polybutylene terephthalate resin, and polycarbonate resin: 100 parts by weight; (B) olefin-based elastomer and / or styrene-based elastomer: 1 to 70 parts by weight.

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