Resin composition and molded article

Abstract

The present invention provides a resin composition that allows for the production of a molded article that achieves excellent moldability while simultaneously possessing sliding properties, wear resistance, and heat resistance, and a molded article containing the resin composition. [Solution] A resin composition comprising 50 to 70 parts by mass of a 4-methyl-1-pentene polymer (A), 5 to 25 parts by mass of an ethylene polymer (B), and 20 to 30 parts by mass of an inorganic filler (C).

Description

[Technical Field]

[0001] This invention relates to resin compositions and molded articles. [Background technology]

[0002] 4-methyl-1-pentene polymers, whose main constituent monomer is 4-methyl-1-pentene, are widely used in various applications due to their excellent properties such as moldability, heat resistance, release properties, and chemical resistance. For example, they are used in FPC release films, composite material molding, and release films, taking advantage of their good release properties. They are also used in laboratory equipment and mandrels for rubber hose manufacturing, taking advantage of their chemical resistance, water resistance, and transparency.

[0003] As described above, 4-methyl-1-pentene polymers possess excellent physical properties, and attempts have been made to further enhance these properties or impart new functions by adding various additives to create resin compositions. For example, Patent Document 1 discloses a 4-methyl-1-pentene resin composition that can produce molded articles with excellent sliding properties and wear resistance, comprising a 4-methyl-1-pentene resin that satisfies predetermined requirements, a modified 4-methyl-1-pentene resin that satisfies predetermined requirements, a predetermined polar resin, and a modified polyethylene resin that satisfies predetermined requirements, wherein the content ratios of these materials are within a predetermined range. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-143066 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the molded article made of the resin composition described in Patent Document 1 had room for improvement in terms of heat resistance, and thus, there was a demand for a resin composition capable of obtaining a molded article that achieved both sliding characteristics, abrasion resistance, and heat resistance.

[0006] The present invention has been made in view of the above problems, and provides a resin composition capable of obtaining a molded article that achieves both sliding characteristics, abrasion resistance, and heat resistance while maintaining excellent moldability, and a molded article containing the resin composition.

Means for Solving the Problems

[0007] As a result of investigations to solve the above problems, the present inventors have found that a resin composition containing a 4-methyl-1-pentene polymer, an ethylene polymer, and an inorganic filler in specific proportions can achieve both sliding characteristics, abrasion resistance, and heat resistance while maintaining excellent moldability when formed into a molded article, and have thus completed the present invention.

[0008] The present invention relates to the following [1] to

[11] . [1] A resin composition comprising 50 to 70 parts by mass of a 4-methyl-1-pentene polymer (A), 5 to 25 parts by mass of an ethylene polymer (B), and 20 to 30 parts by mass of an inorganic filler (C). [2] The resin composition according to [1], wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-1): (A-1) The melting point (Tm) measured by differential scanning calorimetry (DSC) is 175 to 260°C. [3] The resin composition according to [1] or [2], wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-2): (A-2) The melt flow rate (MFR) at 260°C under a load of 5.00 kg measured in accordance with ASTM D1238 is in the range of 0.01 to 1000 g / 10 min. [4] The resin composition according to any one of [1] to [3], wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-3): (A-3) The content (U1) of the structural unit derived from 4-methyl-1-pentene is 100 to 90.0 mol%, and the content (U2) of the structural unit derived from an olefin selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10.0 mol%. [5] The resin composition according to any one of [1] to [4], wherein the ethylene polymer (B) satisfies the following requirement (B-1). Requirement (B-1): Ultra-high molecular weight polyethylene (b1) having an intrinsic viscosity [η] measured in a decalin solvent at 135°C of 10 to 40 dL / g, and Low molecular weight to high molecular weight polyethylene (b2) having an intrinsic viscosity [η] measured in a decalin solvent at 135°C of 0.1 to 5 dL / g are included, and when the total of (b1) and (b2) is 100 parts by mass, the content of (b1) is 5 to 45 parts by mass. [6] The resin composition according to any one of [1] to [5], wherein the ethylene polymer (B) satisfies the following requirement (B-2). (B-2): The density measured in accordance with ASTM D1505 is 955 to 980 kg / m 3 and the intrinsic viscosity [η] measured in a decalin solvent at 135°C is in the range of 1.5 to 15 dL / g. [7] The resin composition according to any one of [1] to [6], wherein the inorganic filler (C) contains barium sulfate. [8] The inorganic filler (C) further contains zinc sulfide, and the resin composition according to [7], wherein the content of barium sulfate in the inorganic filler (C) is 40 to 90% by mass, and the content of zinc sulfide is 10 to 60% by mass. [9] The resin composition is the resin composition according to any one of [1] to [8] that satisfies both of the following requirements (X-1) and (X-2). (X-1) In the Suzuki-type ring wear test (test temperature 23°C, mating material S45C, load 0.50 MPa, speed 30 m / min, distance 0.9 km), the average wear coefficient is 0.35 or less. (X-2) The temperature of deflection under load exceeds 85°C according to JIS K7191 (heating rate: 120°C per hour, test load: 0.45 MPa).

[10] A molded article comprising the resin composition described in any of [1] to [9].

[11] The molded article according to

[10] , which is a film or a sheet. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin composition that can produce a molded article that achieves both sliding properties, wear resistance, and heat resistance while maintaining excellent moldability, and a molded article containing the resin composition. [Modes for carrying out the invention]

[0010] The present invention will be described below, but the various monomers in the present invention may be derived from fossil raw materials, from biological sources such as biomass, or from mixtures thereof. Here, "biomass-derived" means that it can be obtained from any renewable natural raw materials and their residues, including fungi, yeasts, algae, and bacteria, which are of plant or animal origin. Monomers derived from biomass are carbon 14 10 C isotopes -12 ~10 -14 While it contains a certain proportion, the corresponding monomers derived from fossil fuels are 14 Due to the radioactive decay of C 14 It is known that it does not contain carbon. Therefore, monomers derived from biomass and monomers derived from fossil fuels are different. 14It can be distinguished depending on whether or not it contains C isotopes. The biomass-derived monomer can be obtained by a known method.

[0011] In addition, in the present invention, the “4-methyl-1-pentene polymer” is a general term for a 4-methyl-1-pentene homopolymer and a copolymer of 4-methyl-1-pentene and a monomer other than 4-methyl-1-pentene. Furthermore, in the present invention, the “ethylene polymer” is a general term for an ethylene homopolymer and a copolymer of ethylene and a monomer other than ethylene.

[0012] In addition, in this specification, the “structural unit derived from 4-methyl-1-pentene” means a structural unit corresponding to 4-methyl-1-pentene, that is, a structural unit represented by -CH2-CH(-CH2-CH(-CH3)2)-, and the “structural unit derived from ethylene” means a structural unit corresponding to ethylene, that is, a structural unit represented by -CH2-CH2-. The “structural unit derived from α-olefin” is similarly interpreted, and means a structural unit corresponding to α-olefin, that is, a structural unit represented by -CH2-CRR’- (R and R’ are each independently hydrogen or an alkyl group).

[0013] In addition, in this specification, the expression “x~y” (x and y are numerical values, provided that x≠y) representing a numerical range means “x or more and y or less” when x<y, and “x or less and y or more” when x>y, unless otherwise specified.

[0014] [4-Methyl-1-pentene polymer (A)] The resin composition of the present invention contains a 4-methyl-1-pentene polymer (A). The 4-methyl-1-pentene polymer (A) preferably satisfies one or more requirements selected from the group consisting of the following requirements (A-1) to (A-3): (A-1) The melting point (Tm) measured by differential scanning calorimetry (DSC) is 175 to 260 °C; (A-2) The melt flow rate (MFR) measured in accordance with ASTM D1238 at 260°C under a 5.00 kg load is in the range of 0.01 to 1000 g / 10 min; (A-3) The content of structural units derived from 4-methyl-1-pentene (U1) is 100 to 90.0 mol%, and the content of structural units derived from olefins selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) (U2) is 0 to 10.0 mol%.

[0015] In one preferred and exemplary embodiment of the present invention, the 4-methyl-1-pentene polymer (A) preferably satisfies the above requirement (A-1). In another preferred and exemplary embodiment of the present invention, the 4-methyl-1-pentene polymer (A) preferably satisfies requirement (A-2) above. In another preferred and exemplary embodiment of the present invention, the 4-methyl-1-pentene polymer (A) preferably satisfies the above requirement (A-3). The 4-methyl-1-pentene polymer (A) more preferably satisfies two or more requirements selected from the group consisting of requirements (A-1) to (A-3), and even more preferably satisfies all of requirements (A-1) to (A-3). The requirements (A-1) to (A-3) above will be explained in detail below.

[0016] Requirements (A-1) The 4-methyl-1-pentene polymer (A) constituting the resin composition according to the present invention has a melting point (Tm) measured by differential scanning calorimetry (DSC) in the range of 175 to 260°C, preferably 200 to 260°C, more preferably 210 to 250°C, even more preferably 215 to 245°C, and particularly preferably 220 to 240°C. When the melting point (Tm) of the 4-methyl-1-pentene polymer (A) is within the above range, the heat resistance of the molded article obtained from the resin composition containing the 4-methyl-1-pentene polymer (A) is improved.

[0017] Requirements (A-2) The 4-methyl-1-pentene polymer (A) constituting the resin composition according to the present invention has a melt flow rate (MFR) measured in accordance with ASTM D1238 at 260°C and a 5.00 kg load, preferably in the range of 0.01 to 1000 g / 10 min, more preferably 30 to 180 g / 10 min, even more preferably 50 to 150 g / 10 min, and particularly preferably 70 to 145 g / 10 min. When the MFR of the 4-methyl-1-pentene polymer (A) is within the above range, the moldability of the resin composition containing the 4-methyl-1-pentene polymer (A) is improved.

[0018] Requirements (A-3) The 4-methyl-1-pentene polymer (A) constituting the resin composition according to the present invention preferably has a content (U1) of structural units derived from 4-methyl-1-pentene in the range of 100 to 90.0 mol%, more preferably 100 to 93.0 mol%, and even more preferably 99.5 to 95.0 mol%, and a content (U2) of structural units derived from olefins selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) in the range of 0 to 10.0 mol%, more preferably 0 to 7.0 mol%, and even more preferably 0.5 to 5.0 mol% [with the total amount of (U1) and (U2) being 100 mol%].

[0019] monomers constituting the 4-methyl-1-pentene polymer (A) The 4-methyl-1-pentene polymer (A) constituting the resin composition according to the present invention may be a 4-methyl-1-pentene homopolymer, or a copolymer of 4-methyl-1-pentene and a monomer other than 4-methyl-1-pentene. Examples of copolymers of 4-methyl-1-pentene and a monomer other than 4-methyl-1-pentene include copolymers of 4-methyl-1-pentene and an olefin selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene).

[0020] When the 4-methyl-1-pentene polymer (A) is a copolymer of 4-methyl-1-pentene and an olefin selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), specific examples of ethylene and α-olefins having 3 to 20 carbon atoms that copolymerize with 4-methyl-1-pentene include ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Of these, ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene are preferred. These α-olefins may be used individually or in combination of two or more. In one preferred and exemplary embodiment of the present invention, the 4-methyl-1-pentene polymer (A) is a 4-methyl-1-pentene / 1-decene copolymer.

[0021] Other requirements for 4-methyl-1-pentene polymer (A) The 4-methyl-1-pentene polymer (A) constituting the resin composition according to the present invention preferably satisfies one or more requirements selected from the group consisting of the above requirements (A-1) to (A-3), or, in place of one or more requirements selected from the group consisting of the above requirements (A-1) to (A-3), at least one or more requirements selected from the group consisting of the following requirements (A-4) and (A-5), for example, both of the following requirements (A-4) and (A-5). In one particularly preferred embodiment of the present invention, the 4-methyl-1-pentene polymer (A) satisfies all of the above requirements (A-1) to (A-3), as well as the following requirements (A-4) and (A-5). (Requirement (A-4)) The 4-methyl-1-pentene polymer (A) has a heat of fusion of preferably 15 J / g or more, more preferably 15 to 50 J / g, even more preferably 20 to 50 J / g, and particularly preferably 25 to 50 J / g, as measured by differential scanning calorimetry (DSC). When the heat of fusion is within the above range, the heat resistance increases, contributing to an improvement in the load deflection temperature. The heat of fusion of the 4-methyl-1-pentene polymer (A) can be arbitrarily adjusted by appropriately selecting the comonomer species and their amounts.

[0022] (Requirement (A-5)) The 4-methyl-1-pentene polymer (A) has an intrinsic viscosity [η] measured in decalin at 135°C, preferably in the range of 1.00 to 4.00 dl / g, more preferably 1.20 to 3.80 dl / g, and even more preferably 1.40 to 3.50 dl / g. An intrinsic viscosity [η] within this range facilitates injection molding.

[0023] Method for producing 4-methyl-1-pentene polymer (A) The method for producing the 4-methyl-1-pentene polymer (A) is not particularly limited as long as the objective of the present invention is achieved. The 4-methyl-1-pentene polymer (A) can be obtained by homopolymerizing 4-methyl-1-pentene in the presence of a suitable olefin polymerization catalyst, or by copolymerizing 4-methyl-1-pentene with an olefin (hereinafter referred to as "comonomer") selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), as described above in "Monomers constituting the 4-methyl-1-pentene polymer (A)". The olefin polymerization catalyst that can be used to produce the 4-methyl-1-pentene polymer (A) may be a known olefin polymerization catalyst. In one preferred and exemplary embodiment of the present invention, the olefin polymerization catalyst that can be used to produce the 4-methyl-1-pentene polymer (A) is a solid titanium catalyst. Examples of solid titanium catalysts include a solid titanium catalyst component (I) containing titanium, magnesium, and halogen elements, as well as 2,2-dialkyl-1,3-dialkoxypropane, and an organometallic compound catalyst component (II). In this case, the physical properties of the 4-methyl-1-pentene polymer obtained by polymerization can be appropriately adjusted by changing various conditions, such as the presence and type of comonomer that can be used in combination with 4-methyl-1-pentene, the ratio of 4-methyl-1-pentene to comonomer, the type of 2,2-dialkyl-1,3-dialkoxypropane constituting the solid titanium catalyst component (I), the presence and type of a second 2,2-dialkyl-1,3-dialkoxypropane that can be used in combination with the solid titanium catalyst component (I) and the organometallic compound catalyst component (II), and the amount of hydrogen that can be introduced during polymerization, with reference to descriptions such as International Publication No. 2006 / 054613. However, the 4-methyl-1-pentene polymer (A) is not limited to one obtained by a solid titanium catalyst. To the extent that the objectives of the present invention can be achieved, it may also be obtained by homopolymerizing 4-methyl-1-pentene in the presence of an olefin polymerization catalyst other than a solid titanium catalyst, or by copolymerizing 4-methyl-1-pentene with a comonomer. Polymerization in the presence of a solid titanium catalyst or an olefin polymerization catalyst other than a solid titanium catalyst may be carried out as a single-step polymerization method or as a multi-step polymerization method. The resin composition of the present invention may contain only one type of 4-methyl-1-pentene polymer (A), or it may contain two or more types. When the resin composition contains two or more types of 4-methyl-1-pentene polymer (A), the mixture of the two or more types of 4-methyl-1-pentene polymer (A) can also be obtained by a multi-stage polymerization method. That is, the 4-methyl-1-pentene polymer (A) may be obtained by a manufacturing method that includes at least two steps, including the step of producing a first 4-methyl-1-pentene polymer (a1) and the step of producing a second 4-methyl-1-pentene polymer (a2) in the presence of a suitable olefin polymerization catalyst such as the solid titanium catalyst.

[0024] [Ethylene polymer (B)] The resin composition of the present invention contains an ethylene polymer (B). The ethylene polymer (B) constituting the resin composition according to the present invention is not particularly limited, and examples include known high-density polyethylene, low-density polyethylene, and linear low-density polyethylene such as ethylene-α-olefin copolymer. The ethylene polymer (B) preferably satisfies one or more requirements selected from the group consisting of the following requirements (B-1) to (B-2). In particular, the ethylene polymer (B) that satisfies requirement (B-1) is preferred, and it is more preferable that it satisfies both requirements (B-1) to (B-2). Requirements (B-1): Ultra-high molecular weight polyethylene (b1) with an intrinsic viscosity [η] of 10-40 dL / g measured in decalin solvent at 135°C, Low molecular weight or high molecular weight polyethylene (b2) with an intrinsic viscosity [η] of 0.1 to 5 dL / g measured in decalin solvent at 135°C and Includes, When the sum of (b1) and (b2) is 100 parts by mass, the content of (b1) is between 5 and 45 parts by mass. Requirement (B-2): The density measured in accordance with ASTM D1505 was 955-980 kg / m³. 3 The intrinsic viscosity [η] measured in decalin solvent at 135°C is in the range of 1.5 to 15 dL / g. The ethylene polymer (B) more preferably satisfies all of the above requirements (B-1) to (B-2). The requirements (B-1) and (B-2) above will be explained in detail below.

[0025] Requirements (B-1) The ethylene polymer (B) constituting the resin composition according to the present invention contains, with a total amount of ultra-high molecular weight polyethylene (b1) of 100 parts by mass, preferably 5 to 45 parts by mass, more preferably 5 to 30 parts by mass, even more preferably 5 to 28 parts by mass, and particularly preferably 8 to 25 parts by mass of ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2), and contains, with a total amount of 55 to 95 parts by mass, more preferably 70 to 95 parts by mass, even more preferably 72 to 95 parts by mass, and particularly preferably 75 to 92 parts by mass of low molecular weight to high molecular weight polyethylene (b2).

[0026] By including ultra-high molecular weight polyethylene (b1) and low-molecular-weight to high-molecular-weight polyethylene (b2) in the above proportions in the ethylene polymer (B), a resin composition with excellent abrasion resistance and moldability can be obtained.

[0027] The following describes ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2) in ethylene-based polymers (B).

[0028] • Ultra-high molecular weight polyethylene (b1) The ultra-high molecular weight polyethylene (b1) that can constitute the ethylene-based polymer (B) is polyethylene with an intrinsic viscosity [η] of 10 to 40 dL / g, as measured in decalin solvent at 135°C. Ultra-high molecular weight polyethylene (b1) is, for example, a homopolymer of ethylene, or a copolymer of ethylene and α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, or 3-methyl-1-pentene. In particular, it is preferable to use a homopolymer of ethylene or a copolymer of ethylene and the aforementioned α-olefins, wherein ethylene is the main component, and a homopolymer of ethylene is especially preferred.

[0029] The ultra-high molecular weight polyethylene (b1) contained in the ethylene polymer (B) has an intrinsic viscosity [η] of 10-40 dL / g, preferably 20-40 dL / g, and more preferably 25-35 dL / g in decalin solvent at 135°C. By using ultra-high molecular weight polyethylene with such an intrinsic viscosity [η], properties such as abrasion resistance are improved.

[0030] • Low molecular weight or high molecular weight polyethylene (b2) The low-molecular-weight to high-molecular-weight polyethylene (b2) (which may be simply referred to as "polyethylene (b2)" in this specification) that can constitute the ethylene-based polymer (B) is polyethylene having an intrinsic viscosity [η] of 0.1 to 5 dL / g as measured in decalin solvent at 135°C. Low molecular weight or high molecular weight polyethylene (b2) is, for example, a homopolymer of ethylene or a copolymer of ethylene and α-olefins. Examples of α-olefins constituting the copolymer of ethylene and α-olefins are linear or branched α-olefins having 3 to 20 carbon atoms, specifically including propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 3,4-dimethyl-1-pentene, 4-methyl-1-hexene, 3-ethyl-1-pentene, 3-ethyl-4-methyl-1-pentene, 3,4-dimethyl-1-hexene, 4-methyl-1-heptene, 3,4-dimethyl-1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0031] Among these, propylene and 1-butene are preferably used. The low molecular weight to high molecular weight polyethylene (b2) is preferably an ethylene·α-olefin copolymer composed mainly of ethylene, more preferably having an ethylene content of 60 mol% or more, still more preferably having an ethylene content of 80 mol% or more, and particularly preferably an ethylene homopolymer.

[0032] The low molecular weight to high molecular weight polyethylene (b2) has an intrinsic viscosity [η] in decalin at 135 °C of 0.1 to 5 dL / g, preferably 0.2 to 1.0 dL / g, more preferably 0.3 to 0.8 dL / g. By using such low molecular weight to high molecular weight polyethylene with an intrinsic viscosity [η], properties such as moldability are improved. Here, when the ethylene-based polymer (B) is obtained by a multi-stage polymerization method such as the following method (2) described later in the following "Method for Producing Ethylene-based Polymer (B)", the intrinsic viscosity [η] of the low molecular weight to high molecular weight polyethylene (b2) can be estimated using the intrinsic viscosity [η] of the ethylene-based polymer (B) (the entire ethylene-based polymer (B)) defined in requirement (B-2), the intrinsic viscosity [η] of the above ultra-high molecular weight polyethylene (b1), and the contents (mass%) of the above ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2) in the ethylene-based polymer (B). For example, when the ethylene-based polymer (B) consists only of the above ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2), the intrinsic viscosity [η] of the low molecular weight to high molecular weight polyethylene (b2) can be estimated based on the following formula: [η] all = [η] A × wt A + [η] B × wt B [η] all : Intrinsic viscosity of the entire ethylene-based polymer (B) (dL / g) [η] A : Intrinsic viscosity of the ultra-high molecular weight polyethylene (b1) (dL / g) wt A : Content (by mass) of ultra-high molecular weight polyethylene (b1) [η] B : Intrinsic viscosity (dL / g) of low-molecular-weight or high-molecular-weight polyethylene (b2) wt B : Content (by mass) of low molecular weight or high molecular weight polyethylene (b2)

[0033] Other polyethylene components that can constitute ethylene polymer (B) As described above, the ethylene polymer (B) constituting the resin composition according to the present invention preferably contains ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2) in specific proportions. In one preferred and exemplary embodiment of the present invention, the ethylene polymer (B) consists only of ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2). However, the ethylene polymer (B) is not limited to such an embodiment, and may also contain, to the extent that it does not impair the objective of the present invention, high molecular weight polyethylene (b3) having an intrinsic viscosity [η] greater than 5 dL / g and less than 10 dL / g in addition to ultra-high molecular weight polyethylene (b1) and low molecular weight to high molecular weight polyethylene (b2). When such polyethylene (b3) is included, its content in the ethylene polymer (B) is preferably less than 10% by mass, more preferably less than 5% by mass.

[0034] Requirements (B-2) The ethylene-based polymer (B) preferably satisfies the following requirements (i) and (ii). (i) The density of the ethylene polymer (B) is 955-980 kg / m³ 3 (Measured in accordance with ASTM D1505), preferably 957-970 kg / m³ 3 Comfortably 960-969 kg / m 3 That is the case.

[0035] (ii) The intrinsic viscosity [η] of the ethylene polymer (B), measured in decalin solvent at 135°C, is 1.5 to 15 dL / g, preferably 2.0 to 10 dL / g, and more preferably 3.5 to 7.5 dL / g.

[0036] The ethylene polymer (B), having a density within the above range, provides an excellent balance of abrasion resistance, rigidity, and impact resistance in the resulting resin composition. Furthermore, having an intrinsic viscosity [η] within the above range results in an excellent abrasion resistance, impact strength, appearance, and moldability of the resulting resin composition.

[0037] • Method for producing ethylene polymer (B) There are no particular restrictions on the method for producing the ethylene polymer (B). The following (1) and (2) can be given as examples of typical embodiments of the production method.

[0038] (1) A method of production by blending ultra-high molecular weight polyethylene (b1) produced in the presence of a known olefin polymerization catalyst with low molecular weight or high molecular weight polyethylene (b2) produced in the presence of a known olefin polymerization catalyst.

[0039] (2) A method for producing polyethylene by a multi-stage polymerization method comprising at least two steps: (I) a step of producing ultra-high molecular weight polyethylene (b1) in the presence of a known olefin polymerization catalyst, and (II) a step of producing low molecular weight or high molecular weight polyethylene (b2).

[0040] In particular, the method described in (2) above is preferable to the method described in (1) above because it can form a structure in which (b1) and (b2) are more finely dispersed. Here, regarding the method described in (2) above, the specific conditions for carrying out step (I) for producing ultra-high molecular weight polyethylene (b1) and step (II) for producing low molecular weight or high molecular weight polyethylene (b2) are not particularly limited as long as the objectives of the present invention are achieved. For example, when using a Ziegler-Natta catalyst, a carrier-supported solid titanium catalyst, or a metallocene catalyst as the catalyst for olefin polymerization, step (I) can be carried out in an atmosphere that contains little or no hydrogen, and step (II) can be carried out in an atmosphere that contains a relatively large amount of hydrogen. Furthermore, in the method described in (2) above, the order in which steps (I) and (II) are carried out is not particularly limited as long as the objectives of the present invention are achieved, but it is particularly preferable to carry out step (I) as the first step, followed by step (II) as the second step, from the viewpoint of controlling the polymerization operation and the physical properties of the produced polyethylene. In this process, any of the olefins listed in the sections on low molecular weight or high molecular weight polyethylene (b2) and ultra-high molecular weight polyethylene (b1) can be used without limitation as the ethylene or other olefin used in polymerization.

[0041] The ethylene polymer (B) is preferably an ethylene polymer produced by a method including the following steps, having an intrinsic viscosity [η] in decalin at 135°C in the range of 1.5 to 15 dL / g. (I) A process for producing ultra-high molecular weight polyethylene (b1) having an intrinsic viscosity [η] in the range of 10 to 40 dL / g. (II) A process for producing low-molecular-weight or high-molecular-weight polyethylene (b2) having an intrinsic viscosity [η] in the range of 0.1 to 5 dL / g.

[0042] For example, by performing step (I) above first, followed by step (II) above in the same batch, a multi-step polymerization method can be used to form a more finely dispersed structure compared to a method of mixing two types of polyethylene. Furthermore, compared to a continuous production method (non-batch method), a composition with more uniform properties can be obtained stably.

[0043] As catalysts for olefin polymerization used in the polymerization of polyethylene and the like, any catalyst capable of producing ultra-high molecular weight polyethylene and low or high molecular weight polyethylene can be used without particular limitations. Specifically, examples include Ziegler-Natta catalysts consisting of titanium tetrachloride or titanium trichloride, support-supported solid titanium catalysts in which titanium is supported on a support such as magnesium, metallocene catalysts, and post-metallocene catalysts.

[0044] A preferred embodiment for obtaining the ethylene-based polymer (B) according to the present invention is to use a solid titanium catalyst component having a particle size of several micrometers to about 25 μm and a tendency for a narrow particle size distribution. A preferred example is a catalyst containing a solid titanium catalyst component produced using a liquid magnesium compound, a liquid titanium compound, and an electron donor as needed, as shown in Japanese Patent Publication No. 56-811 and Japanese Patent Publication No. 58-83006.

[0045] The ethylene polymer (B) may be an unmodified ethylene polymer (B0), or a modified product (graft-modified ethylene polymer (B1)) obtained by graft-modifying the unmodified ethylene polymer (B0) and introducing functional groups.

[0046] The functional groups used for modification are not particularly limited, but examples include carboxyl groups, amino groups, hydroxyl groups, and silanol groups.

[0047] Examples of structural units containing the aforementioned functional groups include those derived from compounds such as unsaturated carboxylic acids or their derivatives (e.g., anhydrides of unsaturated carboxylic acids such as maleic anhydride), hydroxyl group-containing ethylenically unsaturated compounds, amino group-containing ethylenically unsaturated compounds, and vinyl group-containing organosilicon compounds.

[0048] Graft modification of the ethylene polymer (B) can be carried out by known methods, for example, by the method described in Japanese Patent Application Publication No. 2019-143066. The graft-modified ethylene polymer (B1) can be obtained, for example, by reacting an unmodified ethylene polymer (B0) with a compound for imparting structural units containing the functional group (for example, an unsaturated carboxylic acid or its derivative, a hydroxyl group-containing ethylenically unsaturated compound, an amino group-containing ethylenically unsaturated compound, or a vinyl group-containing organosilicon compound) in the presence of a radical initiator. Here, as the unmodified ethylene polymer (B0), an ethylene polymer that substantially does not contain functional groups selected from the group consisting of carboxyl groups, amino groups, hydroxyl groups, and silanol groups can be used, such as the ethylene polymer obtained by method (1) or (2) above.

[0049] The radical initiator used for graft modification is not particularly limited and examples include organic peroxides and azo compounds. The radical initiator can be used directly mixed with the unmodified ethylene polymer (B0) and the compound for conferring structural units containing functional groups, or it can be used after being dissolved in a small amount of organic solvent. Any organic solvent capable of dissolving the radical initiator can be used without particular limitations.

[0050] [Inorganic filler (C)] The resin composition of the present invention contains an inorganic filler (C). The inorganic filler (C) that can be used in the present invention is not particularly limited and may be any known inorganic filler. Examples of such inorganic fillers include talc, calcium carbonate, mica, barium sulfate, zinc sulfide, calcium silicate, clay, magnesium carbonate, alumina, silica, and fiber reinforcing agents such as glass fibers, carbon fibers, and aramid fibers. These inorganic fillers may be used individually or in combination of two or more. In particular, the inorganic filler (C) preferably contains barium sulfate, and more preferably contains barium sulfate and zinc sulfide. When the inorganic filler contains barium sulfate and zinc sulfide, the barium sulfate content in the inorganic filler (C) is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, and even more preferably 60 to 80% by mass, and the zinc sulfide content is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 40% by mass.

[0051] [Resin composition] The resin composition of the present invention is 50 to 70 parts by mass of the aforementioned 4-methyl-1-pentene polymer (A), The ethylene polymer (B) comprises 5 to 25 parts by mass, The inorganic filler (C) comprises 20 to 30 parts by mass, Includes. The content of the 4-methyl-1-pentene polymer (A) is preferably 60 to 69 parts by mass, more preferably 65 to 68 parts by mass, from the viewpoint of heat resistance, and preferably 50 to 65 parts by mass, more preferably 50 to 60 parts by mass, from the viewpoint of sliding properties and wear resistance. Furthermore, from the viewpoint of balancing heat resistance, sliding properties and wear resistance, it is also preferable to have a content of 55 to 68 parts by mass of the 4-methyl-1-pentene polymer (A), and more preferably 57 to 65 parts by mass. The content of the ethylene polymer (B) is preferably above a certain level to ensure sufficiently high sliding properties and wear resistance, while it is preferably below a certain level to ensure sufficiently high heat resistance and a certain level of injection moldability. From the viewpoint of heat resistance, the content of the ethylene polymer (B) is preferably 5 to 15 parts by mass, more preferably 5 to 8 parts by mass, and from the viewpoint of sliding properties and wear resistance, it is preferably 8 to 25 parts by mass, more preferably 15 to 25 parts by mass. Furthermore, from the viewpoint of balancing heat resistance and injection moldability with sliding properties and wear resistance, the content of the ethylene polymer (B) is also preferably 5 to 25 parts by mass, and more preferably 7 to 15 parts by mass. The content of the inorganic filler (C) is preferably above a certain level to ensure sufficiently high heat resistance, while it is preferably below a certain level to ensure sufficiently high sliding properties and wear resistance, as well as a certain level of granulation stability. From the viewpoint of heat resistance, the content of the inorganic filler (C) is preferably 25 to 30 parts by mass, more preferably 28 to 30 parts by mass, and from the viewpoint of sliding properties and wear resistance, it is preferably 21 to 28 parts by mass, more preferably 22 to 25 parts by mass. Furthermore, from the viewpoint of balancing heat resistance with sliding properties, wear resistance, and granulation stability, the content of the inorganic filler (C) is also preferably 22 to 30 parts by mass, and more preferably 25 to 28 parts by mass.

[0052] The total content of the 4-methyl-1-pentene polymer (A), the ethylene polymer (B), and the inorganic filler (C) in the resin composition is usually 97.0% by mass or more, preferably 98.0% by mass or more, and more preferably 99.0% by mass or more, when the mass of the resin composition is 100% by mass. The upper limit of the total content of the 4-methyl-1-pentene polymer (A), the ethylene polymer (B), and the inorganic filler (C) may be 100% by mass of the resin composition. That is, the resin composition of the present invention may consist only of the 4-methyl-1-pentene polymer (A), the ethylene polymer (B), and the inorganic filler (C), or it may further contain other components ("other components") that do not fall under any of the 4-methyl-1-pentene polymer (A), the ethylene polymer (B), and the inorganic filler (C). If the resin composition contains other components (for example, other polymer components or additives described later), the upper limit is defined by the proportion of the other components.

[0053] The resin composition preferably satisfies one or more requirements selected from the group consisting of the following requirements (X-1) and (X-2), and more preferably satisfies both of the following requirements (X-1) and (X-2). (X-1) In the Suzuki-type ring wear test (test temperature 23°C, mating material S45C, load 0.50 MPa, speed 30 m / min, distance 0.9 km), the average wear coefficient is 0.35 or less. (X-2) The temperature of deflection under load exceeds 85°C according to JIS K7191 (heating rate: 120°C per hour, test load: 0.45 MPa). Here, in requirement (X-1) above, the "average wear coefficient" is the average value of multiple dynamic friction coefficients obtained when the dynamic friction coefficient is measured at regular intervals (for example, every 30 seconds) while the Suzuki ring wear test is being performed. The Suzuki ring wear test can be performed, for example, in the manner described in the "average wear coefficient" section of the example below.

[0054] [Other polymer components] The resin composition of the present invention may further contain other polymer components other than the 4-methyl-1-pentene polymer (A) and the ethylene polymer (B). Examples of other polymer components include 4-methyl-1-pentene copolymers other than the 4-methyl-1-pentene polymer (A).

[0055] If the resin composition contains polymer components other than the 4-methyl-1-pentene polymer (A) and the ethylene polymer (B), the content of these polymer components is usually 3.0 parts by mass or less, preferably 2.0 parts by mass or less, and more preferably 1.0 part by mass or less, when the total content of the 4-methyl-1-pentene polymer (A), the ethylene polymer (B), and the inorganic filler (C) is 100 parts by mass.

[0056] [Additives] The resin composition of the present invention may contain a 4-methyl-1-pentene polymer (A), an ethylene polymer (B), and an inorganic filler (C), as well as an optional "other polymer component," and may also contain a conventionally known additive that does not fall under any of the above categories. Examples of additives include secondary antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, organic fillers, and hydrochloric acid absorbers. The content of additives is not particularly limited, but if the total of 4-methyl-1-pentene polymer (A), ethylene polymer (B), and inorganic filler (C) is 100 parts by mass, then each is usually 0 to 50 parts by mass, preferably 0 to 10 parts by mass. These additives may be used individually or in combination of two or more.

[0057] [Method for producing resin composition] The resin composition of the present invention can be obtained, for example, by mixing a 4-methyl-1-pentene polymer (A), an ethylene polymer (B), and an inorganic filler (C) with other polymer components and additives as needed.

[0058] Regarding the method of mixing each component, various known methods can be employed, such as mixing each component using equipment such as a plast mill, Henschel mixer, V-blender, ribbon blender, tumbler, blender, or kneader-ruder; or, after mixing, the resulting mixture can be further melt-kneaded using equipment such as a single-screw extruder, twin-screw extruder, kneader, or Banbury mixer, and the resulting melt-kneaded product can be granulated or pulverized. In one preferred and exemplary embodiment of the present invention, the melt-kneading is performed using a twin-screw extruder.

[0059] [Molded body] The molded article of the present invention comprises the resin composition described above. The molded articles of the present invention are obtained by using the resin composition of the present invention and subjecting them to known thermoforming methods such as extrusion molding, injection molding, inflation molding, blow molding, extrusion blow molding, injection blow molding, stretch blow molding, press molding, stamping molding, vacuum molding, calendering, filament molding, foam molding, and powder slush molding. In one preferred and exemplary embodiment of the present invention, the molded article of the present invention is an injection molded article. The molded article of the present invention may be a film or a sheet, for example, a film or sheet obtained by subjecting the resin composition of the present invention to the known thermoforming method described above. [Examples]

[0060] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0061] [Measurement and Evaluation Methods] In the following examples and comparative examples, the methods for measuring and evaluating each physical property and characteristic are as follows.

[0062] (1) Physical properties of 4-methyl-1-pentene polymer (A) <MFR> The melt flow rate (MFR) was measured at 260°C under a 5.00 kg load, in accordance with ASTM D1238.

[0063] <Content of structural units> The content of structural units derived from 4-methyl-1-pentene and structural units (comonomers) derived from ethylene and at least one olefin selected from α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) in the 4-methyl-1-pentene polymer (A) is determined by the following apparatus and conditions: 13 The result was obtained from the 1C-NMR spectrum. Using a Bruker BioSpin AVANCE III Cryo-500 nuclear magnetic resonance spectrometer, the solvent was a mixed solvent of o-dichlorobenzene / benzene-d6 (4 / 1 v / v), the sample concentration was 55 mg / 0.6 mL, the measurement temperature was 120°C, and the observed nucleus was 13 The measurement was performed using C (125 MHz), a single-pulse proton broadband decoupling sequence, a pulse width of 5.0 μs (45° pulse), a repetition time of 5.5 seconds, and 64 integration cycles. Benzene-d6 at 128 ppm was used as the reference value for the chemical shift. The content of structural units derived from comonomers was calculated using the integral value of the main chain methine signal and the following formula. Content of structural units derived from comonomers (%) = [P / (P+M)] × 100 Here, P represents the total peak area of ​​the comonomer main chain methine signal, and M represents the total peak area of ​​the 4-methyl-1-pentene main chain methine signal.

[0064] <Melting point (Tm), heat of fusion> Using a DSC measuring device (DSC220C) manufactured by Seiko Instruments Inc., the exothermic and endothermic curves were determined, and the temperature at the position of the maximum melting peak during heating was defined as the melting point (Tm). The measurement was performed as follows: Approximately 5 mg of the pellet sample was packed into a measuring aluminum pan, and the temperature was increased from 20°C to 280°C at a heating rate of 10°C / min. After holding at 280°C for 5 minutes, the temperature was lowered to 20°C at a cooling rate of 10°C / min, held at 20°C for 5 minutes, and then the temperature was again increased from 20°C to 280°C at a heating rate of 10°C / min, and then lowered again to 50°C at a cooling rate of 50°C / min. The melting peak that appeared during the second heating was defined as the melting point (Tm). The heat of fusion was also determined from that melting peak. If there were multiple melting peaks, the value with the strongest peak intensity was defined as the melting point.

[0065] (2) Physical properties of ethylene polymer (B) <density> The density of ethylene polymer (B) was measured in accordance with ASTM D1505.

[0066] <Intrinsic viscosity [η]> The intrinsic viscosity [η] of the ethylene polymer (B) is measured at 135°C using decalin solvent. Specifically, the sample (approximately 20 mg) was dissolved in decalin solvent (15 mL), and the specific viscosity ηsp was measured in an oil bath at 135°C. After diluting this decalin solution by adding decalin solvent (5 mL), the specific viscosity ηsp was measured again in the same manner. This dilution procedure was repeated two more times, and the value of ηsp / C when the sample concentration (C) was extrapolated to 0 was taken as the intrinsic viscosity [η] of the sample. Intrinsic viscosity [η]=lim(ηsp / C) (C→0)

[0067] (3) Physical properties of the resin composition <Granulation stability> When granulation was performed for 1 hour under the conditions described in the examples, a level where the strand did not break was evaluated as ○, and a level where the strand broke once or more was evaluated as ×.

[0068] <Injection moldability> Using a Meiki Co., Ltd. M-70B injection molding machine, 20 samples of 3mm thick injection-molded resin pieces were obtained under injection conditions of cylinder temperature 300°C, mold temperature 60°C, and cooling time 20 seconds. For each of the 20 samples, the presence or absence of breakage in three parts—the molded product body, sprue, and runner—was checked. If, upon removal from the molding machine, no breakage is observed in any of the 20 samples, including the molded product body, sprue, and runner, then it is evaluated as "○". If, during removal from the molding machine, one or more of the 20 samples showed breakage in one or more parts of the molded product body, sprue, or runner, it was evaluated as "×".

[0069] <Average abrasion coefficient> A 3mm thick injection-molded specimen of resin composition was produced using a Meiki Co., Ltd. M-70B injection molding machine under the conditions of cylinder temperature 300°C, mold temperature 60°C, and cooling time 20 seconds. The resulting test specimens were subjected to a ring abrasion test using a Suzuki-type ring abrasion tester in accordance with JIS K7218 "Method A of sliding abrasion test for plastics" to measure the coefficient of dynamic friction. The test conditions were as follows: material: S45C, speed: 30 m / min, distance: 0.9 km, load: 0.50 MPa, and ambient temperature: 23°C. The coefficient of dynamic friction was measured every 30 seconds using the method described above, and the average value of the dynamic coefficient of wear measured until the end of the test was defined as the average coefficient of wear. If the average coefficient of wear was 0.35 or less, it was evaluated that the effect of the present invention had been achieved, and a score of "○" was assigned. On the other hand, if the average coefficient of wear exceeded 0.35, it was evaluated that the effect of the present invention had not been achieved, and a score of "×" was assigned.

[0070] <Load deflection temperature test> Using an M-70B injection molding machine manufactured by Meiki Co., Ltd., a 4mm thick injection-molded test specimen of resin composition was used under the conditions of cylinder temperature 300°C, mold temperature 60°C, and cooling time 20 seconds. In accordance with JIS K7191, a heat deformation temperature test was conducted using an HDT measuring device manufactured by Yasuda Seiki Seisakusho Co., Ltd., under the conditions of heating rate: 120°C per hour and test load: 0.45 MPa, and the load deflection temperature was measured. If the load deflection temperature measured by the above method exceeds 85°C, the effect of the present invention was evaluated as being achieved, and a score of "○" was assigned. On the other hand, if the load deflection temperature is 85°C or less, the effect of the present invention was evaluated as not being achieved, and a score of "×" was assigned.

[0071] [Main constituent materials used in the examples] In the examples and comparative examples, the following were used as the 4-methyl-1-pentene polymer (A), ethylene polymer (B), and inorganic filler (C) constituting the resin composition.

[0072] <4-methyl-1-pentene polymer (A)> As the 4-methyl-1-pentene polymer (A), the 4-methyl-1-pentene copolymer (A-1) obtained in the following production example A1 was used.

[0073] [Manufacturing Example A1] In Comparative Example 7 of International Publication No. 2006 / 054613, a 4-methyl-1-pentene / 1-decene copolymer (hereinafter, 4-methyl-1-pentene copolymer (A-1)) was obtained in the same manner as in Comparative Example 7 of International Publication No. 2006 / 054613, except that the amount of each monomer charged was changed so that the content of structural units derived from 4-methyl-1-pentene and 1-decene in the resulting copolymer was 97.9 mol% for 4-methyl-1-pentene structural units and 2.1 mol% for 1-decene structural units. The obtained 4-methyl-1-pentene copolymer (A-1) had a molecular weight (MFR) of 100 g / 10 min (measured according to ASTM D1238 at 260°C under a 5.00 kg load), an intrinsic viscosity [η] of 1.59 dL / g measured in decalin at 135°C, and a melting point (Tm) and heat of fusion of 232°C and 39 J / g measured by DSC.

[0074] <Ethylene polymer (B)> As the ethylene polymer (B), the ethylene polymer (B-1) obtained in the following production example B1 was used.

[0075] [Manufacturing example B1] A solid titanium catalyst component was prepared in accordance with the preparation of a solid titanium catalyst component described in Production Example 3 of Japanese Patent Publication No. 2019-143066, and stored as a decance slurry. After adding 12 L of purified n-decane to a 24 L autoclave with a stirrer that had been thoroughly purged with nitrogen, 14 mmol of triethylaluminum (in terms of aluminum) and 0.3 mmol of the above-mentioned solid titanium catalyst component (in terms of titanium) were added. Polymerization was started by supplying ethylene at a rate of 4.2 L / min while thoroughly stirring and raising the temperature to 45°C. The internal pressure of the autoclave was 6 kg / cm². 2 The mixture was maintained at G. The polymerization temperature was maintained at 45-46°C. When 880 L of ethylene was supplied, the ethylene supply was temporarily stopped, and the internal pressure reached 3 kg / cm². 2 The temperature was kept constant until it reached G, and then the pressure was quickly reduced to atmospheric pressure. (At this stage, a small sample of the obtained slurry was taken and washed with decane and hexane to obtain a white solid sample (1).) Next, 41 liters of hydrogen were introduced, and the second stage of polymerization was started while raising the temperature to 85°C and supplying ethylene at a rate of 11.6 L / min. The total pressure was 6.4 kg / cm². 2 • The temperature was maintained at 85°C. After supplying 3800L of ethylene, the ethylene supply was stopped, and the internal pressure reached 3kg / cm². 2 The temperature was maintained at 85°C until the result was G, then the pressure was reduced to normal and the temperature cooled, and polymerization was completed. After polymerization was complete, a solid white substance was separated from the obtained slurry, washed with decane and hexane, and then dried under reduced pressure at 80°C to obtain an ethylene polymer (ethylene polymer (B-1)) in the form of a white solid. The density of the obtained white solid was 967 kg / cm³. 3 (Measured in accordance with ASTM D1505), the intrinsic viscosity [η] was 5.73 dL / g. On the other hand, the white solid sample (1) was confirmed to be ultra-high molecular weight polyethylene (b1) because its intrinsic viscosity [η] was 28 dL / g. Furthermore, based on the amount of ethylene supplied, the content of ultra-high molecular weight polyethylene (b1) produced in the first stage was 19.0% by mass. The intrinsic viscosity of the polymer produced in the second stage was estimated to be 0.5 dL / g using the following formula, confirming that the polymer produced in the second stage is low molecular weight or high molecular weight polyethylene (b2). [η] all =[η] A ×wt A +[η] B ×wt B [η] all : Intrinsic viscosity (dL / g) of the entire polymer (ethylene-based polymer (B-1)) [η] A Intrinsic viscosity (dL / g) of ultra-high molecular weight polyethylene (b1) wt A : Content (by mass) of ultra-high molecular weight polyethylene (b1) [η] B : Intrinsic viscosity (dL / g) of low-molecular-weight or high-molecular-weight polyethylene (b2) wt B : Content (by mass) of low molecular weight or high molecular weight polyethylene (b2) In other words, the ethylene polymer (B-1) contains 19.0 parts by mass of ultra-high molecular weight polyethylene (b1) with respect to 100 parts by mass of the total amount of ultra-high molecular weight polyethylene (b1) and polyethylene (b2). <Inorganic filler (C)> The inorganic filler (C-1) described below was used as the inorganic filler (C): Inorganic filler (C-1): An inorganic filler containing 70% by mass of barium sulfate and 30% by mass of zinc sulfide.

[0076] [Examples 1-3 and Comparative Examples 1-5] Using a twin-screw extruder (PCM43, manufactured by Ikegai Co., Ltd., screw diameter: 43 mm, temperature: 280°C, rotation speed: 200 rpm), 4-methyl-1-pentene / 1-decene copolymer (A-1), ethylene polymer (B-1), and inorganic filler (C-1) were melt-kneaded in the proportions shown in Table 1, and each resin composition was obtained in pellet form by granulation using the strand-cut method. For each resin composition obtained in the examples and comparative examples, various physical properties were measured and evaluated using the method described in "Measurement and Evaluation Method" above. The results are shown in Table 1 below.

[0077] [Table 1]

Claims

1. 50 to 70 parts by mass of 4-methyl-1-pentene polymer (A), 5 to 25 parts by mass of ethylene polymer (B), Inorganic filler (C) 20 to 30 parts by mass, A resin composition containing the following:

2. The resin composition according to claim 1 wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-1): (A-1) The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 175 and 260°C.

3. The resin composition according to claim 1 or 2, wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-2): (A-2) The melt flow rate (MFR) measured in accordance with ASTM D1238 at 260°C and a 5.00 kg load is in the range of 0.01 to 1000 g / 10 min.

4. The resin composition according to claim 1 or 2, wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirement (A-3): (A-3) The content of structural units derived from 4-methyl-1-pentene (U1) is 100 to 90.0 mol%, and the content of structural units derived from olefins selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) (U2) is 0 to 10.0 mol%.

5. The resin composition according to claim 1 or 2, wherein the ethylene polymer (B) satisfies the following requirement (B-1). Requirement (B-1): Ultra-high molecular weight polyethylene (b1) having an intrinsic viscosity [η] of 10-40 dL / g measured in decalin solvent at 135°C, Low molecular weight to high molecular weight polyethylene (b2) having an intrinsic viscosity [η] of 0.1 to 5 dL / g measured in decalin solvent at 135°C and Includes, When the sum of (b1) and (b2) is 100 parts by mass, the content of (b1) is 5 to 45 parts by mass.

6. The resin composition according to claim 1 or 2, wherein the ethylene polymer (B) satisfies the following requirement (B-2). (B-2): The density measured in accordance with ASTM D1505 was 955–980 kg / m³. 3 The intrinsic viscosity [η] measured in decalin solvent at 135°C is in the range of 1.5 to 15 dL / g.

7. The resin composition according to claim 1 or 2, wherein the inorganic filler (C) contains barium sulfate.

8. The inorganic filler (C) further contains zinc sulfide, The resin composition according to claim 7, wherein the inorganic filler (C) contains 40 to 90% by mass of barium sulfate and 10 to 60% by mass of zinc sulfide.

9. The resin composition according to claim 1 or 2, wherein the resin composition satisfies both of the following requirements (X-1) and (X-2). (X-1) In the Suzuki-type ring wear test (test temperature 23°C, mating material S45C, load 0.50 MPa, speed 30 m / min, distance 0.9 km), the average wear coefficient is 0.35 or less. (X-2) The temperature of deflection under load exceeds 85°C according to JIS K7191 (heating rate: 120°C per hour, test load: 0.45 MPa).

10. A molded article comprising the resin composition according to claim 1 or 2.

11. The molded article according to claim 10, which is a film or a sheet.

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