Ethylene-based polymer composition and its use

Abstract

To provide an ethylenic polymer composition that can give a molding having excellent wear resistance.SOLUTION: An ethylenic polymer composition contains 100 pts.mass of an ethylenic polymer component (A) with an intrinsic viscosity [η] of 3.0-10 dl / g as measured in a decalin solvent at 135°C and with a density of 930-980 kg / m3, and 8-80 pts.mass of an inorganic filler (B). The ethylenic polymer component (A) includes an ultra-high-molecular-weight ethylenic polymer (a1) with an intrinsic viscosity [η] of 10-40 dl / g as measured in a decalin solvent at 135°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ethylene-based polymer composition and its use. [Background technology]

[0002] Polyethylene resin is widely used as a molding material because it is easy to mold, has various excellent physical properties, and is economical. For example, Patent Document 1 discloses a composition containing high-density polyethylene and talc, and an inflation film made of this composition, while Patent Document 2 discloses a high-density polyethylene resin composition containing high-density polyethylene resin and layered silicate, and an injection-molded article of this composition, etc. Furthermore, Patent Document 3 discloses a resin composition containing a polyolefin resin (polyethylene resin, polypropylene resin, etc.), multi-walled carbon nanotubes, and an inorganic filler, and a molded article of this composition.

[0003] On the other hand, Patent Document 4 discloses a polyethylene resin composition containing ultra-high molecular weight polyethylene and low- to high-molecular weight polyethylene, and a resin composition containing a polyolefin-based resin composition, and describes that this resin composition is excellent in mechanical properties, abrasion resistance, appearance, moldability, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-126663 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-19733 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-196012 [Patent Document 4] International Publication No. 2003 / 022920 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional ethylene polymer compositions containing inorganic fillers have room for further improvement from the viewpoint of obtaining molded articles having excellent abrasion resistance. Therefore, an object of the present invention is to provide an ethylene polymer composition from which molded articles having excellent abrasion resistance can be obtained, and a molded article thereof. [Means for solving the problem]

[0006] The present invention relates to, for example, the following [1] to

[11] . [1] The intrinsic viscosity [η] measured in decalin solvent at 135°C is 3.0 to 10 dl / g, and the density is 930 to 980 kg / m 3 100 parts by mass of an ethylene polymer component (A) represented by the formula: 8 to 80 parts by mass of inorganic filler (B) Contains the ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) having an intrinsic viscosity [η] of 10 to 40 dl / g as measured in decalin solvent at 135°C; Ethylene-based polymer composition.

[0007] [2] The ethylene polymer composition according to [1] above, wherein the ethylene polymer component (A) comprises a low-molecular-weight to high-molecular-weight ethylene polymer (a2) having an intrinsic viscosity [η] of 0.1 to 9 dl / g as measured in decalin solvent at 135°C.

[0008] [3] the ethylene polymer component (A) contains 10 to 90 mass% of an ethylene polymer component (AI) and 90 to 10 mass% of an ethylene polymer component (AII) (the total amount of the components (AI) and (AII) being 100 mass%), The ethylene polymer component (AI) is A step of producing the ultra-high molecular weight ethylene polymer (a1) in an amount of more than 35 mass % but not more than 90 mass %; a step of producing 10% by mass or more and less than 65% by mass of the low-molecular-weight to high-molecular-weight ethylene polymer (a2) (the total amount of polymer (a1) and polymer (a2) being 100% by mass); obtained by a multi-stage polymerization method comprising The ethylene polymer component (AII) contains an ethylene polymer (a3) ​​having an intrinsic viscosity [η] of 0.1 to 2.9 dl / g as measured in decalin solvent at 135°C. The ethylene polymer composition according to [2] above.

[0009] [4] The ethylene polymer composition according to any one of [1] to [3] above, wherein the inorganic filler (B) is at least one selected from the group consisting of talc and kaolin.

[0010] [5] The ethylene polymer composition according to any one of the above [1] to [4], which contains a conductive filler (C).

[0011] [6] The ethylene polymer composition according to [5] above, wherein the conductive filler (C) is a carbon nanotube.

[0012] [7] The ethylene polymer composition according to any one of the above [1] to [6], which contains a modified olefin polymer (D).

[0013] [8] A molded article comprising the ethylene polymer composition according to any one of [1] to [7] above. [9] The molded article according to [8] above, which is an injection molded article.

[0014]

[10] The molded body according to [8] above, which is a coating material.

[11] The molded body according to [8] above, which is a sliding material. [Effects of the Invention]

[0015] According to the ethylene polymer composition of the present invention, a molded article having excellent abrasion resistance can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will now be described in further detail. The ethylene polymer composition according to the present invention comprises: The intrinsic viscosity [η] is 3.0 to 10 dl / g, and the density is 930 to 980 kg / m 3 100 parts by mass of an ethylene polymer component (A) represented by the formula: 8 to 80 parts by mass of inorganic filler (B) Contains The ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) having an intrinsic viscosity [η] of 10 to 40 dl / g. It is characterized by the following.

[0017] In the present invention, the intrinsic viscosity [η] is the intrinsic viscosity [η] measured in decalin solvent at 135° C. unless otherwise specified.

[0018] <Ethylene-based polymer component (A)> The ethylene polymer component (A) is a homopolymer of ethylene or a copolymer of ethylene and an α-olefin, and is a polymer mainly composed of ethylene, generally known as high-pressure low-density polyethylene (HP-LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ultra-high molecular weight ethylene polymer, or the like.

[0019] When the ethylene polymer component (A) is a copolymer, it may be a random copolymer or a block copolymer. The α-olefin copolymerized with ethylene is preferably an α-olefin having 3 to 20 carbon atoms, and specific examples thereof include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. These α-olefins may be used singly or in combination of two or more.

[0020] The ethylene polymer component (A) may be a single polymer or a composition (mixture) of two or more ethylene polymers. The ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) (hereinafter also referred to as "polymer (a1)") having an intrinsic viscosity [η] of 10 to 40 dl / g.

[0021] Since the ethylene polymer component (A) contains the polymer (a1), the composition of the present invention can provide a molded article having excellent abrasion resistance, self-lubricating properties, impact strength, chemical resistance, and the like. The intrinsic viscosity [η] of the polymer (a1) is preferably 15 to 35 dl / g, more preferably 20 to 35 dl / g.

[0022] The ethylene polymer component (A) may contain a low-molecular-weight to high-molecular-weight ethylene polymer (a2) (hereinafter also referred to as "polymer (a2)") having an intrinsic viscosity [η] of 0.1 to 9 dL / g. The polymer (a2) may be a wax.

[0023] The intrinsic viscosity [η] of the polymer (a2) is preferably 0.1 to 5 dl / g, more preferably 0.5 to 3 dl / g, and even more preferably 1.0 to 2.5 dl / g. The composition of the present invention preferably contains, as the ethylene polymer component (A), A step of producing the ultra-high molecular weight ethylene polymer (a1) in an amount of more than 35 mass % but not more than 90 mass %; a step of producing 10% by mass or more and less than 65% by mass of the low-molecular-weight to high-molecular-weight ethylene polymer (a2) (the total amount of polymer (a1) and polymer (a2) being 100% by mass); 10 to 90% by mass of an ethylene polymer component (AI) obtained by a multistage polymerization method comprising the steps of: 90 to 10 mass% of an ethylene polymer component (AII) having an intrinsic viscosity [η] of 0.1 to 2.9 dl / g (the total amount of components (AI) and (AII) is taken as 100 mass%) Contains.

[0024] In the multi-stage polymerization method, the polymer (a1) is usually produced in the first stage, and then the polymer (a2) is produced in the second stage. The proportion of the ethylene polymer component (AI) is preferably 15 to 90 mass%, more preferably 20 to 80 mass%, and even more preferably 26.7 to 49 mass%, and the proportion of the ethylene polymer component (AII) is preferably 85 to 10 mass%, more preferably 80 to 20 mass%, and even more preferably 73.3 to 51 mass% (the total amount of components (AI) and (AII) being 100 mass%).

[0025] Ethylene polymer component (AI) The ultra-high molecular weight ethylene polymer (a1) constituting the ethylene polymer component (AI) is usually obtained in the first stage polymerization in a multi-stage polymerization method.

[0026] The low-molecular-weight to high-molecular-weight ethylene polymer (a2) constituting the ethylene polymer component (AI) is usually obtained in a second-stage polymerization after polymerization of the polymer (a1) in a multistage polymerization method.

[0027] The ethylene polymer component (AI) can be produced by polymerizing ethylene and, if desired, an α-olefin in multiple stages in the presence of a catalyst, and the multiple stage polymerization can be carried out by a method similar to the polymerization method described in JP-A-2-289636.

[0028] Furthermore, by polymerizing the polymer (a1) and then post-polymerizing the polymer (a2), the ethylene polymer component (AI) has excellent compatibility with the ethylene polymer component (AII), and as a result, the ultra-high molecular weight ethylene polymer (a1) is uniformly dispersed in the composition of the present invention, and the ultra-high molecular weight ethylene polymer (a1) is bonded to the ethylene polymer component (AII), i.e., the interfacial strength between the polymer (a1) and the ethylene polymer component (AII) is increased. Therefore, when the composition of the present invention contains the component (AI) and the component (AII), it has an excellent balance of properties such as wear resistance, self-lubrication, impact strength, chemical resistance, appearance, and moldability, and is particularly excellent in the balance of wear resistance, appearance, and moldability.

[0029] The ethylene polymer component (AI) contains the ultra-high molecular weight ethylene polymer (a1) in an amount of more than 35% by mass and not more than 90% by mass, preferably more than 40% by mass and not more than 80% by mass, more preferably from 41 to 75% by mass, and contains the low-molecular weight to high-molecular weight ethylene polymer (a2) in an amount of from 10% by mass to less than 65% by mass, preferably from 20% by mass to less than 60% by mass, more preferably from 25 to 59% by mass.

[0030] By setting the ratio of polymer (a1) to polymer (a2) within the above range, the compatibility between component (AI) and component (AII) is improved, and the composition of the present invention is particularly excellent in abrasion resistance, appearance, and moldability.

[0031] The ethylene polymer component (AI) substantially comprises only an ultra-high molecular weight ethylene polymer (polymer (a1)) and a low- to high-molecular weight ethylene polymer (polymer (a2)).

[0032] Component (AI) may contain additives that are typically added to polyolefins (for example, stabilizers such as heat stabilizers and weather stabilizers, crosslinking agents, crosslinking aids, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, mineral oil-based softeners, petroleum resins, waxes, etc.), and the composition of the present invention may contain the additives added to component (AI) as long as the effects of the present invention are not impaired.

[0033] The density of the ethylene polymer component (AI) (measured in accordance with ASTM D1505) is usually 930 to 980 kg / m 3 , preferably 940 to 970 kg / m 3 is. The intrinsic viscosity [η] of the ethylene polymer component (AI) is usually 3.0 to 10.0 dl / g, preferably 3.0 to 8.0 dl / g, and more preferably 3.0 to 7.0 dl / g.

[0034] When the ethylene polymer component (AI) has the density as described above, the coefficient of dynamic friction of the molded article is reduced, and therefore, a molded article having excellent self-lubricating properties can be obtained. Furthermore, when the ethylene polymer component (AI) has an intrinsic viscosity [η] within the above range, the ethylene polymer component (AI) and the ethylene polymer component (AII) are well dispersed.

[0035] That is, the polymer (a2) contained in the ethylene polymer component (AI) and the ethylene polymer component (AII) melt-blended in an extruder or the like are mutually finely dispersed to form a uniform dispersion state, and therefore, by using the ethylene polymer component (AI), a molded article excellent in abrasion resistance, self-lubrication, impact strength, chemical resistance, appearance, moldability, etc. can be obtained from the composition of the present invention.

[0036] Ethylene-based polymer component (AII) The ethylene polymer component (AII) contains an ethylene polymer (a3) ​​having an intrinsic viscosity [η] of 0.1 to 2.9 dl / g.

[0037] Examples of the ethylene polymer (a3) ​​include high-pressure polyethylene (HP-LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-α-olefin copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, saponified ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, and ethylene-α-olefin-diene (triene, polyene) terpolymers. Examples of α-olefins include those having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Examples of dienes (trienes, polyenes) include conjugated or non-conjugated dienes, trienes, and polyenes, such as 5-ethylidene-2-norbornene and vinylnorbornene.

[0038] The ethylene polymer component (AII) may be a single ethylene polymer (a3), a composition of two or more ethylene polymers (a3), or a composition of the ethylene polymer (a3) ​​and a polyolefin (such as polypropylene or polybutene). The ethylene polymer component (AII) may also be a wax.

[0039] Of the above-mentioned ethylene polymers (a3), high density polyethylene (HDPE) and low density polyethylene (LDPE) are preferred, with high density polyethylene (HDPE) being more preferred.

[0040] The density of the ethylene polymer (a3) ​​(measured in accordance with ASTM D1505) is usually 820 to 980 kg / m 3 , preferably 930 to 980 kg / m 3 , more preferably 950 to 980 kg / m 3 is.

[0041] The intrinsic viscosity [η] of the ethylene polymer (a3) ​​is usually 0.1 to 2.9 dl / g, preferably 0.3 to 2.8 dl / g, more preferably 0.5 to 2.5 dl / g, and even more preferably 1.0 to 2.5 dl / g.

[0042] Since the ethylene polymer component (AII) contains the ethylene polymer (a3), it disperses well when mixed with the ethylene polymer component (AI). That is, during melt blending in an extruder or the like, the ethylene polymer component (AII) and the low-molecular-weight to high-molecular-weight ethylene polymer (a2) contained in the ethylene polymer component (AI) are finely dispersed with each other, resulting in a uniform dispersion state. Therefore, by using the ethylene polymer component (AI) and the ethylene polymer component (AII) as the ethylene polymer component (A), molded articles excellent in wear resistance, self-lubrication, impact strength, chemical resistance, appearance, flexibility, moldability, etc. can be obtained.

[0043] Component (AII) may contain additives that are typically added to polyolefins (e.g., stabilizers such as heat stabilizers and weather stabilizers, crosslinking agents, crosslinking aids, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, mineral oil-based softeners, petroleum resins, waxes, etc.), and the composition of the present invention may contain the additives added to component (AII) as long as the effects of the present invention are not impaired.

[0044] <Inorganic filler (B)> Examples of the inorganic filler (B) include talc, silica, diatomaceous earth, alumina, titanium oxide, calcium oxide, magnesium oxide, iron oxide, antimony oxide, ferrite, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, light calcium carbonate, heavy calcium carbonate, colloidal calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, zeolite, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate (wollastonite, xonotlite), basic magnesium sulfate, clay, kaolin, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica-based balloons, aluminum nitride, boron nitride, silicon nitride, fibrous magnesium, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, and zinc borate. These may be used alone or in combination of two or more.

[0045] Among these, talc and kaolin are preferred from the viewpoint of increasing the rigidity of the molded article without impairing the abrasion resistance. Examples of the shape of the inorganic filler (B) include fibrous, rod-like, needle-like, plate-like, spherical, balloon-like, spindle-like, tetrapod-like, and amorphous shapes. Among these, fibrous, needle-like, and plate-like shapes are preferred from the viewpoint of increasing the rigidity of the molded body without impairing the abrasion resistance.

[0046] The inorganic filler (B) has an average particle size (particle size at which the cumulative value of the particle size distribution curve measured by the liquid phase sedimentation method in accordance with JIS Z8820 is 50%) of, for example, 0.01 to 40 μm, preferably 0.1 to 30.0 μm.

[0047] In the composition of the present invention, the content of the inorganic filler (B) is 8 to 80 parts by mass, preferably 9 to 70 parts by mass, more preferably 10 to 65 parts by mass, and even more preferably 10 to 60 parts by mass, relative to 100 parts by mass of the content of the ethylene polymer component (A). When the content of the inorganic filler (B) is within the above range, a molded article having excellent abrasion resistance can be obtained from the composition of the present invention.

[0048] <Conductive filler (C)> The composition according to the present invention may contain a conductive filler (C). From the composition of the present invention containing the conductive filler (C), a molded article having sliding properties and high electrical conductivity can be obtained.

[0049] Examples of the conductive filler (C) include carbon nanotubes (CNTs), conductive carbon black (CB), and carbon fibers. The conductive filler (C) is not particularly limited as long as it is a material that has conductivity, but among these, carbon nanotubes are preferred because they are excellent in reducing the surface electrical resistivity of the molded body.

[0050] Carbon nanotubes are cylindrical hollow fibrous substances made of carbon, and may be either multi-walled carbon nanotubes or single-walled carbon nanotubes. The average diameter of the carbon nanotubes is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 7 nm or more, and preferably 20 nm or less. The average length of the carbon nanotubes is preferably 0.5 μm or more, more preferably 0.6 μm, and preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 15 μm or less. An average diameter of 1 nm or more tends to make the nanotubes less likely to break during kneading, while an average length of 20 nm or less tends to increase electrical conductivity. An average length of 0.5 μm or more tends to increase electrical conductivity, while an average length of 50 μm or less tends to suppress an increase in viscosity during kneading, making kneading and molding easier.

[0051] The average diameter and average length of the carbon nanotubes can be determined by observing the carbon nanotubes under an electron microscope (SEM, TEM) and calculating the arithmetic mean. Carbon nanotubes can be produced by, for example, arc discharge, chemical vapor deposition (CVD), or laser ablation. Commercially available carbon nanotubes may also be used.

[0052] Carbon nanotubes tend to exhibit high conductivity in a relatively small amount compared to, for example, carbon black, but are expensive, so it is advantageous from the viewpoint of cost if they can be used in a smaller amount. In this embodiment, excellent conductivity can be obtained by using an ethylene polymer composition containing a conductive filler (C) and an ethylene polymer (A), so that high conductivity tends to be obtained even with a small amount of carbon nanotubes.

[0053] Examples of conductive carbon black include furnace black, ketjen black, channel black, lamp black, thermal black, and acetylene black. Specific examples include HAF-LS, HAF, HAF-HS, FEF, GPF, APF, SRF-LM, SRF-HM, and MT.

[0054] The primary particle diameter of the conductive carbon black is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 1 μm or less, more preferably 0.2 μm or less. The primary particle diameter is the average particle diameter measured using an electron microscope or the like.

[0055] As the carbon fiber, various known carbon fibers can be used, for example, polyacrylonitrile-based, rayon-based, pitch-based, polyvinyl alcohol-based, regenerated cellulose-based, pitch-based carbon fibers produced from mesophase pitch, etc. Carbon fibers have an advantage in that they have excellent specific strength, in applications where light weight and strength are important, such as for aircraft.

[0056] The carbon fiber may be a general-purpose fiber or a high-strength fiber, and may be a long fiber, a short fiber, a chopped fiber, or a recycled fiber. As a sizing agent (sizing agent) for carbon fibers, for example, any of urethane-based emulsion, epoxy-based emulsion, nylon-based emulsion, and olefin-based emulsion can be used.

[0057] The average length of the carbon fibers, i.e., the average fiber length, is preferably 0.1 mm or more, more preferably 0.3 mm or more, even more preferably 0.5 mm or more, and is preferably 15.0 mm or less, more preferably 13.0 mm or less. When the average fiber length is 0.1 mm or more, the reinforcing effect of the carbon fibers on mechanical properties tends to be sufficiently exhibited. When the average fiber length is 15.0 mm or less, the carbon fibers are dispersed in the ethylene polymer composition, and the appearance of the molded article tends to be good.

[0058] The average diameter of the carbon fibers is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 21 μm or less, and even more preferably 19 μm or less. When the average diameter of the carbon fibers is 3 μm or more, the carbon fibers are less likely to break during molding, and the impact strength of the resulting molded article tends to be high. When the average diameter of the carbon fibers is 30 μm or less, the appearance of the molded article tends to be good, and the aspect ratio of the carbon fibers does not decrease, and a sufficient reinforcing effect tends to be obtained in the mechanical properties such as rigidity and heat resistance of the molded article.

[0059] The conductive filler (C) can be used alone or in combination of two or more kinds. When the composition of the present invention contains the conductive filler (C), the content of the conductive filler (C) in the composition of the present invention is preferably 30 parts by mass or less, more preferably 5 to 25 parts by mass, and even more preferably 10 to 25 parts by mass, relative to 100 parts by mass of the content of the ethylene polymer component (A). When the content of the conductive filler (C) is within the above range, a molded article with excellent conductivity can be obtained from the composition of the present invention.

[0060] <Modified olefin polymer (D)> The composition according to the present invention may contain a modified olefin polymer (D). The modified olefin polymer (D) is used, for example, as a compatibilizer for enhancing the compatibility of the ethylene polymer component (A) with the inorganic filler (B) and the optional conductive filler (C).

[0061] Examples of the modified olefin polymer (D) include acid-modified products (e.g., maleic anhydride-modified products), air-oxide-modified products, or styrene-modified products of homopolymers or copolymers of ethylene and α-olefins having 3 to 12 carbon atoms. Among these, preferred are modified products of polymers selected from the group consisting of ethylene polymers (ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 12 carbon atoms) and propylene polymers (propylene homopolymers and copolymers of propylene and at least one α-olefin selected from α-olefins having 4 to 12 carbon atoms).

[0062] Examples of the α-olefin (α-olefin having 3 to 12 carbon atoms or α-olefin having 4 to 12 carbon atoms) include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0063] The modified olefin polymer (D) is preferably a modified ethylene polymer. The modified olefin polymer (D) is more preferably a modified ethylene polymer (d11) obtained by graft-modifying the following ethylene polymer (d1) with an unsaturated carboxylic acid or a derivative thereof. (d1) Density is 930 to 970 kg / m 3 and a melt flow rate (MFR) of 0.1 to 10 g / 10 min at 190° C. under a load of 2.16 kg, as measured in accordance with ASTM D1238.

[0064] The density of the ethylene polymer (d1) is 930 to 970 kg / m 3 , preferably 940 to 965 kg / m 3 When the density is within the above range, the ethylene polymer component (A) has high compatibility with the inorganic filler (B) and the optional conductive filler (C).

[0065] The melt flow rate of the ethylene polymer (d1) (according to ASTM D1238, 190°C, 2.16 kg load) is 0.1 to 10 g / 10 min, preferably 0.2 to 8 g / 10 min. When the melt flow rate is within this range, the ethylene polymer component (A) is highly compatible with the inorganic filler (B) and the optional conductive filler (C).

[0066] The graft amount of the unsaturated carboxylic acid or its derivative in the modified ethylene polymer (d11) is usually 0.01 to 10 mass %, preferably 0.02 to 5 mass %. When the graft amount is within this range, the ethylene polymer component (A) has high compatibility with the inorganic filler (B) and any of the conductive fillers (C).

[0067] Examples of the unsaturated carboxylic acid or its derivative include unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and nadic acid (endo-cis-bicyclo[2.2.1]hept-5-ene-dicarboxylic acid), and their derivatives, such as acid halides, amide imides, anhydrides, and esters. Specific examples of the derivatives include maleyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, and glycidyl maleate. Among these, unsaturated dicarboxylic acids and their acid anhydrides are preferred, and maleic acid, nadic acid, and their acid anhydrides are more preferred.

[0068] The modified ethylene polymer (d11) can be produced by various known methods. For example, a method of dissolving an ethylene polymer in an organic solvent, adding an unsaturated carboxylic acid or a derivative thereof and, if necessary, a radical initiator such as an organic peroxide to the resulting solution, and reacting them usually at a temperature of 60 to 350°C, preferably 80 to 190°C, for 0.5 to 15 hours, preferably 1 to 10 hours, or a method of using an extruder or the like to add an ethylene polymer, an unsaturated carboxylic acid or a derivative thereof, and, if necessary, a radical initiator such as an organic peroxide, without a solvent, and reacting them usually at a temperature above the melting point of the ethylene polymer, preferably 160 to 350°C, for 0.5 to 10 minutes can be employed.

[0069] The ethylene polymer before modification can be produced by a known method, for example, a high-pressure method or a low-pressure method using a Ziegler-type Ti-based catalyst, a Co-based catalyst, a metallocene-based catalyst, or the like.

[0070] The ethylene polymer (d1) may contain one kind of ethylene polymer alone, or may contain two or more kinds of ethylene polymers. When the ethylene polymer (d1) contains two or more kinds of ethylene polymers, each of the two or more ethylene polymers satisfies the requirements for density and melt flow rate of the ethylene polymer (d1) described above.

[0071] When the composition of the present invention contains the modified olefin polymer (D), the content of the modified olefin polymer (D) in the composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 8 parts by mass, and even more preferably 0.5 to 7 parts by mass, relative to 100 parts by mass of the ethylene polymer component (A). When the content of the modified olefin polymer (D) is within the above range, the ethylene polymer component (A), the inorganic filler (B), and the optional conductive filler (C) can be well compatibilized.

[0072] <Optional ingredients> In addition to the ethylene polymer component (A), inorganic filler (B), conductive filler (C), and modified olefin polymer (D) described above, the ethylene polymer composition of the present invention may contain, as necessary, various additives typically used in polyolefins, such as a heat stabilizer, a weather stabilizer, an ultraviolet absorber, a light stabilizer, a wax, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a dye, a dispersant, a flame retardant, a flame retardant aid, a plasticizer, and a compatibilizer, or an impact modifier such as an elastomer, or a polymer such as a polyamide, within a range that does not impair the effects of the present invention.

[0073] When the ethylene polymer composition of the present invention contains the additive or polymer, the amount thereof is not particularly limited, but is, for example, in the range of 0.01 to 30% by mass. The additive is preferably a wax, and examples of the wax include polyethylene waxes (excluding those corresponding to the ethylene polymer component (AII)) and polypropylene waxes.

[0074] It is believed that when the ethylene-based polymer composition of the present invention contains a wax, aggregation of the inorganic filler (B) and the conductive filler (C) in the ethylene-based polymer component (A) is suppressed, making kneading easier and facilitating dispersion of the inorganic filler (B) and the conductive filler (C) in the ethylene-based polymer component (A).

[0075] When the ethylene polymer composition of the present invention contains a wax, the amount thereof is usually in the range of 0.01 to 10% by mass based on the amount of the entire composition. The MFR of the ethylene polymer composition of the present invention, measured in accordance with JIS K 7210-1:2014 at 190°C under a load of 10 kgf, is usually 0.1 to 20 g / 10 min, and preferably 0.1 to 10 g / 10 min.

[0076] <Method of producing ethylene polymer composition> The ethylene polymer composition of the present invention can be obtained by mixing the ethylene polymer component (A), the inorganic filler (B), optionally the conductive filler (C), optionally the modified olefin polymer (D), and optionally the optional components by a conventionally known method, for example, by dry blending the components, subsequently melt-kneading the mixture in a single-screw or twin-screw extruder, extruding the mixture into strands, and granulating the mixture into pellets.

[0077] The inorganic filler (B) and the conductive filler (C), particularly the conductive filler (C), may be used in the form of a masterbatch by being premixed with a polymer component such as the ethylene polymer component (A).

[0078] <Molded body> The molded article of the present invention contains the ethylene polymer composition. Specific examples of the method for producing the molded article (molding method) include conventionally known polyolefin molding methods, such as extrusion molding, injection molding, film molding, inflation molding, blow molding, extrusion blow molding, injection blow molding, press molding, vacuum molding, powder slush molding, calendar molding, and foam molding. The ethylene polymer composition is preferably processed by injection molding to obtain a molded article containing the ethylene polymer composition.

[0079] The molded article may be a molded article formed from the ethylene polymer composition, or may be a molded article having a portion, such as a surface layer, formed from the ethylene polymer composition.

[0080] Molded articles are used in a wide range of applications, including household goods for daily necessities and recreational purposes, general industrial applications, and industrial goods. Specific examples of molded articles include home appliance material parts, communication device parts, electrical parts, electronic parts, automobile parts, other vehicle parts, ship and aircraft materials, machine mechanism parts, building materials, civil engineering materials, agricultural materials, power tool parts, food containers, films, sheets, and fibers.

[0081] The molded article of the present invention can be widely used for conventionally known polyethylene applications, but since it has an excellent balance of properties such as abrasion resistance, self-lubrication, impact strength, and thin-wall formability, it can be used for applications requiring these properties, such as metal coating materials (laminates) for steel pipes, electric wires, and automobile sliding door rails, pressure-resistant rubber hoses, automobile door gaskets, clean room door gaskets, automobile glass run channels, and various rubber coating materials (laminates) for automobile weather strips, linings for hoppers and chutes, and sliding materials such as gears, bearings, rollers, tape reels, various guide rails and elevator rail guides, and various protective liner materials.

[0082] When the molded article of the present invention contains the conductive filler (C), it also has excellent conductivity, and therefore can suppress the electrostatic charge of various machine parts and sliding members, making it suitable for use in applications where electrical conductivity and anti-static properties are required. [Example]

[0083] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0084] [Measurement method] The physical properties of the compositions obtained in the examples were measured as follows. [Intrinsic viscosity [η]] Measured in decalin at 135°C. [Melt flow rate (MFR)] Measurements were performed in accordance with JIS K7210-1:2014 at a temperature of 190°C and a load of 10 kgf.

[0085] 〔density〕 The density of the ethylene polymer component (A) was measured by the density gradient method in accordance with ASTM D1505. The density of the compositions obtained in the examples and comparative examples was measured in water at 23°C by the liquid weighing method in accordance with JIS Z8807:2012.

[0086] [Flexural strength, flexural modulus] <Preparation of JIS K7162 1A Test Specimens> The compositions obtained in the examples or comparative examples were charged into the hopper of an EC-75SXIII molding machine manufactured by Shibaura Machine Co., Ltd., melted at 250 °C, and injection molded into a mold to prepare JIS K7162 1A test specimens. The mold temperature was set to 50 - 70 °C, the injection pressure to 130 - 150 MPa, and the holding pressure to 80 - 100 MPa. However, only in the case of the compositions obtained in Comparative Examples 2 and 3, the melting temperature was changed to 200 °C, the injection pressure to 80 - 110 MPa, and the holding pressure to 70 - 90 MPa.

[0087] <Measurement of Flexural Strength and Flexural Modulus> Using the JIS K7162 1A test specimens, in accordance with ISO 178, with the test specimen shape being 80 mm (length), 10 mm (width), 4 mm (thickness), a span distance of 64 mm, and a test speed of 2 mm / min, the flexural strength and flexural modulus were determined.

[0088] 〔Charpy Impact Strength〕 JIS K7162 1A test specimens were prepared in the same manner as described above. Using these test specimens, in accordance with ISO 170, notch machining was performed, and the Charpy impact value was measured with a hammer capacity of 4 J.

[0089] 〔Surface Resistivity, Volume Resistivity〕 <Preparation of Test Specimens with a Length of 130 mm × Width of 120 mm × Thickness of 3 mm> The compositions obtained in the examples or comparative examples were charged into the hopper of an EC-75SXIII molding machine manufactured by Shibaura Machine Co., Ltd., melted at 250 °C, and injection molded into a mold to prepare test specimens with a length of 130 mm × width of 120 mm × thickness of 3 mm. The mold temperature was set to 50 - 70 °C, the injection pressure to 30 - 50 MPa, and the holding pressure to 25 - 35 MPa. However, only in the case of the compositions obtained in Comparative Examples 2 and 3, the melting temperature was changed to 200 °C, and the holding pressure was changed to 70 - 90 MPa.

[0090] <Measurement of Surface Resistivity and Volume Resistivity> Using a test piece measuring 130 mm in length, 120 mm in width, and 3 mm in thickness, the surface resistivity and volume resistivity were measured using an ADC Corporation Digital Ultra-High Resistance / Fine Particle Ammeter 8340A by the double ring method under the conditions of 23°C, humidity: 50%, applied voltage: 500 V, and application time: 60 seconds.

[0091] The surface resistivity in the above measurement was 1.0 × 10 7 The following standards were measured in accordance with JIS K7194:1994 using a low resistance resistivity meter, Loresta-GX-MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd., under the conditions of applied current: 1 mA, application time: 10 seconds, 23°C, and humidity: 50%.

[0092] [Friction coefficient, specific wear rate] Test pieces measuring 130 mm long x 120 mm wide x 3 mm thick were punched out from the same method as above to prepare test pieces measuring 30 mm long x 30 mm wide x 3 mm thick. Using these test pieces, the dynamic friction coefficient and specific wear rate were measured using a Matsubara friction and wear tester in accordance with JIS K7218 "Sliding wear test for plastics, Method A."

[0093] The test conditions were: mating material: S45C, speed: 50 cm / sec, distance: 3 km, load: 15 kg, and measurement environment temperature: 23°C. In all of the Examples and Comparative Examples, it was confirmed by visual inspection that the worn components contained the ethylene polymer and inorganic filler.

[0094] [Raw materials] The raw materials used in the examples and comparative examples are as follows.

[0095] (Ethylene polymer component (AI)) <<Production of Ethylene-Based Polymer Component (AI-1)>> Using a conventional method, an ultra-high molecular weight ethylene polymer (polymer (a1)) having an intrinsic viscosity [η] of 30 dL / g was polymerized in a first stage, and then a low molecular weight ethylene polymer (polymer (a2)) having an intrinsic viscosity [η] of 1.5 dL / g was polymerized in a second stage, in a mass ratio (polymer (a1) / polymer (a2)) of 75 / 25, to thereby obtain an ethylene polymer component (AI-1) having an intrinsic viscosity [η] of 6.9 dL / g.

[0096] <<Production of Ethylene-Based Polymer Component (AI-2)>> Using a conventional method, an ultra-high molecular weight ethylene polymer (polymer (a1)) having an intrinsic viscosity [η] of 30 dL / g was produced in a first polymerization stage, followed by a low molecular weight ethylene polymer (polymer (a2)) having an intrinsic viscosity [η] of 1.5 dL / g in a second polymerization stage, in a mass ratio (polymer (a1) / polymer (a2)) of 41 / 59 to produce an ethylene polymer component (AI-2) having an intrinsic viscosity [η] of 4.4 dL / g.

[0097] <<Production of Ethylene-Based Polymer Component (AI-3)>> By a conventional method, an ultra-high molecular weight ethylene polymer (polymer (a1)) having an intrinsic viscosity [η] of 30 dL / g was polymerized in a first stage, and then a low molecular weight ethylene polymer (polymer (a2)) having an intrinsic viscosity [η] of 1.5 dL / g was polymerized in a second stage, in a mass ratio (polymer (a1) / polymer (a2)) of 50 / 50, to obtain an ethylene polymer component (AI-3) having an intrinsic viscosity [η] of 4.7 dL / g.

[0098] (Ethylene-based polymer component (AII)) The following ethylene polymer components were used: Ethylene polymer component (AII-1): Intrinsic viscosity [η] 1.1 dl / g, density 965 kg / m 3 High-density, low-molecular-weight polyethylene (manufactured by Prime Polymer Co., Ltd., product name: Hi-Zex 1700J)

[0099] (Ethylene-based polymer component (A)) <<Production of Ethylene-Based Polymer Component (A-1)>> Ethylene polymer component (AI-1) and ethylene polymer component (AII-1) were blended in a mass ratio ((AI-1) / (AII-1)) of 33 / 67, and melt-blended using an Ikegai PCM twin-screw extruder to obtain pelletized ethylene polymer component (A-1) with an intrinsic viscosity [η] of 5.8 dl / g. The content of ultra-high molecular weight ethylene polymer (polymer (a1)) in ethylene polymer component (A-1) was 25 mass%.

[0100] <<Production of Ethylene-Based Polymer Component (A-2)>> The ethylene polymer component (AI-2) and the ethylene polymer component (AII-1) were mixed in a mass ratio ((AI- 2 The mixture was blended in a ratio of 49 / 51 using a PCM twin-screw extruder manufactured by Ikegai Iron Works, and a pellet-shaped ethylene polymer component (A-2) with an intrinsic viscosity [η] of 3.0 dl / g was obtained. The content of the ultra-high molecular weight ethylene polymer (polymer (a1)) in the ethylene polymer component (A-2) was 20 mass%.

[0101] <<Production of Ethylene-Based Polymer Component (A-3)>> The ethylene polymer component (AI-3) and the ethylene polymer component (AII-1) were mixed in a mass ratio ((AI- 3 The mixture was blended in a ratio of 46 / 54 (AII-1) / (AII-2)) and melt-blended using a PCM twin-screw extruder manufactured by Ikegai Iron Works, to obtain a pelletized ethylene polymer component (A-3) with an intrinsic viscosity [η] of 4.3 dl / g. The content of the ultra-high molecular weight ethylene polymer (polymer (a1)) in the ethylene polymer component (A-3) was 23 mass%.

[0102] (Inorganic filler (B)) The following inorganic fillers were used: Inorganic filler (B-1): Talc (average particle size: 4.5 μm, manufactured by Matsumura Sangyo Co., Ltd., High Filler #5000PJ) Inorganic filler (B-2): Talc (average particle size: 19.0 μm, manufactured by Matsumura Sangyo Co., Ltd., Crown Talc ID) Inorganic filler (B-3): Kaolin (average particle size: 1.4 μm, BASF TRANSLINK 445)

[0103] (Conductive filler (C)) The following conductive fillers were used: Conductive filler (C-1): Carbon nanotubes (average diameter: 9.5 nm, average length: 1.5 μm, Nanosil NC7000)

[0104] (Masterbatch containing conductive filler) <Production of conductive filler-containing masterbatch (MC-1)> A conductive filler-containing masterbatch (MC-1) was produced by mixing 15 mass% of the conductive filler (C-1), 75 mass% of the ethylene polymer component (A-2), and 10 mass% of wax (polyethylene wax).

[0105] <Production of conductive filler-containing masterbatch (MC-2)> A conductive filler-containing masterbatch (MC-2) was produced by mixing 15 mass% of the conductive filler (C-1), 75 mass% of the ethylene polymer component (AII-1), and 10 mass% of wax (polyethylene wax).

[0106] (Modified olefin polymer (D)) The following modified olefin polymers were used as compatibilizers. Modified olefin polymer (D): A maleic acid-modified ethylene polymer (density: 965 kg / cm) produced based on the production method of ethylene polymer PE-0 described in WO 2019 / 209169, paragraphs

[0042] to

[0043] . 3 MFR (190°C, 2.16 kg load): 5 g / 10 min, Modification rate: 2.4)

[0107] [Example 1] 29% by mass of the ethylene polymer component (A-1), 10% by mass of the inorganic filler (B-1), 60% by mass of the conductive filler-containing star batch (MC-1), and 1% by mass of the modified olefin polymer (D) were dry-blended, and then the mixture was charged into the hopper of a BT30 twin-screw extruder manufactured by Plastics Technology Research Institute Co., Ltd. and melt-kneaded at 250°C to obtain Composition 1. The proportions of each component in Composition 1 (based on 100 parts by mass of the total amount of the ethylene polymer) are shown in Table 1. The physical properties of Composition 1 were measured by the methods described above, and the results are shown in Table 1.

[0108] [Examples 2, 3, 7, and 10] A composition was produced in the same manner as in Example 1, except that the amounts of the ethylene polymer component (A-1), inorganic filler (B-1), conductive filler-containing masterbatch (MC-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0109] [Examples 4, 5, and 6] A composition was produced in the same manner as in Example 1, except that inorganic filler (B-3) was used instead of inorganic filler (B-1), and the amounts of ethylene polymer component (A-1), inorganic filler (B-3), conductive filler-containing masterbatch (MC-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0110] [Example 8] A composition was produced in the same manner as in Example 1, except that inorganic filler (B-2) was used instead of inorganic filler (B-1), and the amounts of ethylene polymer component (A-1), inorganic filler (B-2), conductive filler-containing masterbatch (MC-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0111] [Example 9] A composition was produced in the same manner as in Example 1, except that the ethylene polymer component (A-2) was used instead of the ethylene polymer component (A-1), and the amounts of the ethylene polymer component (A-2), inorganic filler (B-1), conductive filler-containing masterbatch (MC-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0112] [Example 11] A composition was produced in the same manner as in Example 1, except that the ethylene polymer component (A-1) was replaced with the ethylene polymer component (A-3), the conductive filler-containing masterbatch (MC-1) was not used, and the amounts of the ethylene polymer component (A-3), inorganic filler (B-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1. The results are shown in Table 1.

[0113] [Example 12] A composition was produced in the same manner as in Example 1, except that the ethylene polymer component (A-1) was replaced with the ethylene polymer component (A-3), the inorganic filler (B-1) was replaced with the inorganic filler (B-3), the conductive filler-containing masterbatch (MC-1) was not used, and the amounts of the ethylene polymer component (A-3), the inorganic filler (B-3), and the modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1. The results are shown in Table 1.

[0114] [Comparative Example 1] A composition was produced in the same manner as in Example 1, except that the amounts of the ethylene polymer component (A-1), inorganic filler (B-1), masterbatch (MC-1) containing conductive filler (C-1), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0115] Comparative Example 2 38% by mass of the ethylene polymer component (AII-1), 20% by mass of the inorganic filler (B-1), 60% by mass of the conductive filler-containing masterbatch (MC-2), and 2% by mass of the modified olefin polymer (D) were dry-blended, and then the mixture was placed in the hopper of a BT30 twin-screw extruder manufactured by Plastics Technology Research Institute Co., Ltd., and melt-kneaded at 200°C to obtain a composition. The physical properties were measured in the same manner as in Example 1. The results are shown in Table 1.

[0116] Comparative Example 3 A composition was produced in the same manner as in Comparative Example 2, except that inorganic filler (B-3) was used instead of inorganic filler (B-1), and the amounts of ethylene polymer component (AII-1), inorganic filler (B-3), conductive filler-containing masterbatch (MC-2), and modified olefin polymer (D) were adjusted to the blending amounts shown in Table 1, and the physical properties of the composition were measured. The results are shown in Table 1.

[0117] [Table 1-1]

[0118] [Table 1-2]

Claims

1. The intrinsic viscosity [η] measured in decalin solvent at 135°C is 3.0 to 10 dl / g, and the density is 930 to 980 kg / m 3 100 parts by mass of an ethylene polymer component (A) 8 to 80 parts by mass of an inorganic filler (B), and 0.5 to 7 parts by mass of modified olefin polymer (D) Contains the ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) having an intrinsic viscosity [η] measured in decalin solvent at 135°C of 10 to 40 dl / g; Ethylene-based polymer composition.

2. 2. The ethylene polymer composition according to claim 1, wherein the ethylene polymer component (A) comprises a low- to high-molecular-weight ethylene polymer (a2) having an intrinsic viscosity [η] of 0.1 to 9 dl / g as measured in decalin solvent at 135°C.

3. the ethylene polymer component (A) contains 10 to 90 mass% of an ethylene polymer component (AI) and 90 to 10 mass% of an ethylene polymer component (AII) (the total amount of the components (AI) and (AII) being 100 mass%); The ethylene polymer component (AI) is a step of producing the ultra-high molecular weight ethylene polymer (a1) in an amount of more than 35% by mass and not more than 90% by mass; and a step of producing 10% by mass or more and less than 65% by mass of the low-molecular-weight to high-molecular-weight ethylene polymer (a2) (the total amount of polymer (a1) and polymer (a2) being 100% by mass); obtained by a multi-stage polymerization method comprising The ethylene polymer component (AII) has an intrinsic viscosity measured in decalin solvent at 135°C. The ethylene polymer (a3) ​​has a viscosity [η] of 0.1 to 2.9 dl / g. The ethylene polymer composition according to claim 2.

4. The ethylene polymer composition according to any one of claims 1 to 3, wherein the inorganic filler (B) is at least one selected from the group consisting of talc and kaolin.

5. The ethylene polymer composition according to any one of claims 1 to 4, further comprising a conductive filler (C).

6. The ethylene polymer composition according to claim 5, wherein the conductive filler (C) is a carbon nanotube.

7. A molded article comprising the ethylene polymer composition according to any one of claims 1 to 6.

8. The molded article according to claim 7, which is an injection molded article.

9. The molded article according to claim 7, which is a coating material.

10. The molded article according to claim 7, which is a sliding material.

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