Ethylene-based polymer compositions and their uses

Abstract

The ethylene polymer composition of the present invention comprises: 100 parts by mass of an ethylene polymer component (A) having an ultimate viscosity [η] of 1.5 to 10 dl / g and a density of 930 to 980 kg / m³ as measured in a decahydronaphthalene solvent at 135°C; and 1 to 100 parts by mass of carbon fiber (B); wherein the aforementioned ethylene polymer component (A) comprises an ultra-high molecular weight ethylene polymer (a1) having an ultimate viscosity [η] of 10 to 40 dl / g as measured in a decahydronaphthalene solvent at 135°C.

Description

Technical Field

[0001] This invention relates to ethylene-based polymer compositions and their uses. Prior Technology

[0002] Polyethylene resin is widely used as a molding material due to its ease of molding, excellent physical properties, and economic efficiency. For example, Patent Document 1 discloses a high-density polyethylene resin composition containing high-density polyethylene resin and layered silicates, and an injection-molded article of the composition. Patent Document 2 discloses a resin composition composed of polyolefin resin (polyethylene resin, polypropylene resin, etc.), multilayer carbon nanotubes, and inorganic fillers, and a molded article of the composition.

[0003] On the other hand, Patent Document 3 discloses a composition containing ultra-high molecular weight polyethylene, an ethylene polymer of low molecular weight or high molecular weight polyethylene, and an ethylene polymer containing carbon nanotubes. It also describes that the resin composition has low surface resistivity and volume resistivity, and good thermal conductivity. The molding system obtained from the ethylene polymer composition has good sliding properties and rigidity. [Previous Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2014-19733 [Patent Document 2] Japanese Patent Application Publication No. 2010-196012 [Patent Document 3] International Publication No. 2022 / 038941 Summary of the Invention

[0005] (The problem the invention aims to solve)

[0006] However, conventional ethylene-based polymer compositions containing inorganic fillers or carbon nanotubes may not have sufficient formability, and there is still room for further improvement from the perspective of obtaining molded articles with excellent rigidity, conductivity, wear resistance and heat resistance.

[0007] Therefore, the purpose of this invention is to provide: an ethylene-based polymer composition and a molded article thereof that can produce a molded article with excellent formability, rigidity, conductivity, wear resistance and heat resistance. (Technical means to solve the problem)

[0008] Examples of the present invention are shown below. [1] An ethylene-based polymer composition comprising: 100 parts by mass of an ethylene-based polymer component (A) having an limiting viscosity [η] of 1.5~10 dl / g and a density of 930~980 kg / m³ as determined in a decahydronaphthalene solvent at 135°C; and 1~100 parts by mass of carbon fiber (B); wherein, The above-mentioned ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) with a limiting viscosity [η] of 10~40 dl / g as measured in decahydronaphthalene solvent at 135℃.

[0009] [2] The ethylene polymer composition described in [1] contains: a low or high molecular weight ethylene polymer (a2) with a limiting viscosity [η] of 0.1 to 9 dl / g as determined in decahydronaphthalene solvent at 135°C.

[0010] [3] The ethylene polymer composition described in [2], wherein the ethylene polymer component (A) contains: 10-90% by mass of ethylene polymer component (AI) and 90-10% by mass of ethylene polymer component (AII) (the total mass of component (AI) and component (AII) is set to 100% by mass); The aforementioned ethylene polymer component (AI) is a multi-segment polymer consisting of: more than 35% by mass and less than 90% by mass of the aforementioned ultra-high molecular weight ethylene polymer (a1), and more than 10% by mass and less than 65% by mass of the aforementioned low molecular weight or high molecular weight ethylene polymer (a2) (the total mass of polymer (a1) and polymer (a2) is set at 100% by mass); The above-mentioned ethylene polymer component (AII) contains: an ethylene polymer (a3) ​​with an ultimate viscosity [η] of 0.1~2.9 dl / g as determined in decahydronaphthalene solvent at 135°C.

[0011] [4] The ethylene polymer composition described in [3] is obtained by a multi-stage polymerization method including the steps of generating the ultra-high molecular weight ethylene polymer (a1) and generating the low molecular weight or high molecular weight ethylene polymer (a2).

[0012] [5] The ethylene polymer composition described in any of [1] to [4], wherein the carbon fiber (B) is a surface-treated carbon fiber. [6] As described in [5], the ethylene polymer composition wherein the surface treatment of the carbon fiber (B) is a sizing treatment using an olefin polymer, a carbamate polymer, a nylon polymer, or an epoxy polymer.

[0013] [7] The ethylene polymer composition described in any of [1] to [6], wherein the average fiber length of the carbon fiber (B) extracted from the ethylene polymer composition is 100 μm or more and 400 μm or less. [8] The ethylene polymer composition described in any of [1] to [7], wherein the proportion of carbon fibers (B) extracted from the ethylene polymer composition having a fiber length of 100 μm or more and 300 μm or less is 30% or more.

[0014] [9] The ethylene polymer composition described in any of [1] to [8] contains a modified olefin polymer (C).

[10] The ethylene polymer composition described in any of [1] to [9], wherein the content of the carbon fiber (B) is 20 to 60 parts by mass relative to 100 parts by mass of the ethylene polymer composition (A).

[0015]

[11] A molded body comprising an ethylene polymer composition as described in any one of [1] to

[10] .

[12] The molded article described in item

[11] , wherein the proportion of the carbon fibers (B) contained in the molded article having a needle ratio of 1.5 or more is 30% or more.

[0016]

[13] The molded body described in

[11] or

[12] , wherein the shrinkage rate in both the length direction and the width direction of the molded body is less than 2.0%.

[14] The molded body described in any of

[11] to

[13] , wherein the flexural modulus of the molded body is 5000 MPa or more.

[0017]

[15] The molded body described in any of

[11] to

[14] , wherein the molded body undergoes more than 1500 repetitions in the vibration fatigue test (35MPa) when the displacement is 8mm.

[16] The molded body described in any of the items

[11] to

[15] is an injection molded body.

[17] The molded body described in any of

[11] to

[16] is a covering material or a sliding material. (Compared to the effectiveness of previous technologies)

[0018] According to the present invention, it can provide: an ethylene-based polymer composition that yields a molded body with excellent formability, rigidity, electrical conductivity, wear resistance and heat resistance, and the molded body thereof. Simple Explanation of the Diagram

[0019] Figure 1 is a schematic diagram illustrating the location of the ASTM D671 Type A test piece (molded body) and the observation surface of the test sample used to evaluate the alignment in the embodiment. Implementation

[0020] The present invention will now be described in detail. Furthermore, in this specification, the numerical range indicated by "~" refers to a range containing the lower and upper limits of the values ​​before and after "~".

[0021] The ethylene polymer composition of the present invention (hereinafter also referred to as "the composition of the present invention") contains: 100 parts by mass of an ethylene polymer component (A) with an limiting viscosity [η] of 1.5 to 10 dl / g and a density of 930 to 980 kg / m3, and 1 to 100 parts by mass of carbon fiber (B); wherein the ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) with an limiting viscosity [η] of 10 to 40 dl / g.

[0022] Furthermore, unless otherwise stated, the limiting viscosity [η] of this invention refers to the limiting viscosity [η] measured in decahydronaphthalene solvent at 135°C.

[0023] <Ethylene-based polymer composition (A)> The above-mentioned ethylene-based polymer component (A) is a homopolymer of ethylene or a copolymer of ethylene and α-olefins. It is generally referred to 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-based polymers, etc., which are polymers with ethylene as the main component.

[0024] When the above-mentioned ethylene-based polymer component (A) is a copolymer, it can be a random copolymer or a block copolymer.

[0025] α-olefins that can copolymerize with ethylene, preferably α-olefins having 3 to 20 carbon atoms, include systems such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, 1-tetradecene, 1-pentadecadecene, 1-hexadecene, 1-heptadecene, 1-nonadecadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. These α-olefin systems can be used alone or in combination of two or more.

[0026] The aforementioned ethylene polymer component (A) can be a single polymer or a mixture of two or more ethylene polymers.

[0027] The limiting viscosity [η] of the above-mentioned ethylene polymer component (A) is 1.5~10 dl / g, preferably 2.0~8.0 dl / g, and even more preferably 2.5~7.0 dl / g. By having the above-mentioned ethylene polymer component (A) with a limiting viscosity [η] within the above range, a molded article with excellent and balanced properties such as wear resistance, self-lubrication, impact strength, chemical resistance, appearance, and formability can be obtained from the composition of the present invention.

[0028] The density of the ethylene polymer component (A) described above (measured according to ASTM D1505) is 930~980 kg / m³, preferably 940~970 kg / m³. By having the ethylene polymer component (A) within the above-mentioned density range, a molded body with excellent wear resistance and flexibility can be obtained.

[0029] The aforementioned ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) with an limiting viscosity [η] of 10~40 dl / g (hereinafter also referred to as "polymer (a1)"). Because the aforementioned ethylene polymer component (A) contains the aforementioned polymer (a1), a molded body with excellent wear resistance, self-lubrication, impact strength, and chemical resistance can be obtained from the composition of the present invention.

[0030] The limiting viscosity [η] of the above polymer (a1) is preferably 15~35 dl / g, and more preferably 20~35 dl / g.

[0031] The aforementioned ethylene polymer component (A) may also contain low- or high-molecular-weight ethylene polymers (a2) with an limiting viscosity [η] of 0.1 to 9 dl / g (hereinafter also referred to as "polymer (a2)"). The aforementioned polymer (a2) may also be a wax.

[0032] The limiting viscosity [η] of the above polymer (a2) is preferably 0.1~5 dl / g, more preferably 0.5~3.0 dl / g, and exceptionally preferably 1.0~2.5 dl / g.

[0033] In the composition of the present invention, it is preferred that the above-mentioned ethylene polymer component (A) contains: 10-90% by mass of ethylene polymer component (AI) and 90-10% by mass of ethylene polymer component (AII) (the total amount of components (AI) and (AII) is set to 100% by mass). Furthermore, the ethylene polymer component (AI) contains: The above-mentioned ultra-high molecular weight ethylene polymers (a1) exceeding 35% by mass and below 90% by mass, and A multi-stage polymer comprising 10% by mass or more but less than 65% by mass of the aforementioned low or high molecular weight ethylene polymer (a2) (the total mass of polymer (a1) and polymer (a2) is set at 100% by mass); The limiting viscosity of the ethylene-based polymer component (AII) is 0.1~2.9 dl / g.

[0034] The aforementioned ethylene polymer component (a1) is preferably obtained by a multi-stage polymerization method including the steps of generating the aforementioned ultra-high molecular weight ethylene polymer (a1) and generating the aforementioned low molecular weight or high molecular weight ethylene polymer (a2).

[0035] In the above multi-stage polymerization method, polymer (a1) is usually generated in the first stage, followed by polymer (a2) in the second stage.

[0036] The preferred proportion of the above-mentioned ethylene polymer component (AI) is 15-90% by mass, the more preferred proportion is 20-80% by mass, and the particularly preferred proportion is 26.7-49% by mass; and the preferred proportion of the above-mentioned ethylene polymer component (AII) is 85-10% by mass, the more preferred proportion is 80-20% by mass, and the particularly preferred proportion is 73.3-51% by mass (the total amount of component (AI) and component (AII) is set to 100% by mass).

[0037] Composition of ethylene-based polymers (AI) The ultra-high molecular weight ethylene polymer (a1) constituting the above-mentioned ethylene polymer component (AI) is usually obtained by polymerization in the first stage of a multi-stage polymerization method.

[0038] The low-molecular-weight or high-molecular-weight ethylene polymer (a2) constituting the above-mentioned ethylene polymer component (AI) is usually obtained by a second stage of polymerization after the above-mentioned polymer (a1) has been polymerized in a multi-stage polymerization process.

[0039] The aforementioned ethylene-based polymer component (AI) can be manufactured by polymerizing ethylene and the desired α-olefin in the presence of a catalyst using a multi-stage polymerization process. The multi-stage polymerization can be carried out using the same method as the polymerization method described in Japanese Patent Application Publication No. 2-289636.

[0040] Furthermore, by first polymerizing the aforementioned polymer (a1) and then subsequently polymerizing the aforementioned polymer (a2), the aforementioned ethylene-based polymer component (A1) exhibits excellent compatibility with the aforementioned ethylene-based polymer component (A2). As a result, in the composition of the present invention, the aforementioned ultra-high molecular weight ethylene-based polymer (a1) is uniformly dispersed, and the aforementioned ultra-high molecular weight ethylene-based polymer (a1) and the aforementioned ethylene-based polymer component (A2) are bonded. That is, the interfacial strength between the aforementioned polymer (a1) and the aforementioned ethylene-based polymer component (A2) can be improved. Therefore, by containing the aforementioned components (A1) and (A2), the composition of the present invention can achieve an excellent balance of properties such as wear resistance, self-lubrication, impact strength, chemical resistance, appearance, and formability, especially an excellent balance of wear resistance, appearance, and formability.

[0041] In the aforementioned ethylene polymer component (AI), the aforementioned ultra-high molecular weight ethylene polymer (a1) is preferably contained in an amount of more than 35% by mass and less than 90% by mass, more preferably more than 40% by mass and less than 80% by mass, and particularly preferably 41% to 75% by mass. Furthermore, the aforementioned low molecular weight or high molecular weight ethylene polymer (a2) is preferably contained in an amount of more than 10% by mass and less than 65% by mass, more preferably more than 20% by mass and less than 60% by mass, and particularly preferably 25% to 59% by mass.

[0042] By setting the ratio of polymer (a1) to polymer (a2) within the above range, the compatibility of component (AI) and component (AII) can be improved, and the composition of the present invention has particularly excellent wear resistance, appearance and formability.

[0043] The aforementioned ethylene polymer components (AI) essentially contain only ultra-high molecular weight ethylene polymers (polymer (a1)) and low or high molecular weight ethylene polymers (polymer (a2)).

[0044] The above-mentioned components (AI) may also contain additives commonly added to polyolefins (e.g., heat stabilizers, weather stabilizers, etc.; crosslinking agents, crosslinking aids, antistatic agents, lubricants, anti-blocking agents, anti-fogging agents, slip agents, dyes, mineral oil-based softeners, petroleum resins, waxes, etc.). The composition of the present invention may also contain additives added to the above-mentioned components (AI) to the extent that it does not impair the effects of the present invention.

[0045] The density of the above-mentioned ethylene polymer components (AI) (measured according to ASTM D1505) is typically 930~980 kg / m³, preferably 940~970 kg / m³. The limiting viscosity [η] of the above-mentioned ethylene polymer components (AI) is typically 3.0~10.0 dl / g, preferably 3.0~8.0 dl / g, and even more preferably 3.0~7.0 dl / g.

[0046] By having the density described above, the ethylene-based polymer component (AI) can reduce the coefficient of dynamic friction of the molded body, thus obtaining a molded body with excellent self-lubricating properties. Furthermore, by having a limiting viscosity [η] within the aforementioned range, the ethylene polymer component (AI) can achieve a good dispersion state between the ethylene polymer component (AI) and the ethylene polymer component (AII).

[0047] That is, by finely dispersing the polymer (a2) contained in the ethylene polymer component (AI) and the ethylene polymer component (AII) whose melt flow rate is achieved using an extruder or the like, a uniform dispersion state can be achieved. Furthermore, by using the ethylene polymer component (AI), a molded article with excellent wear resistance, self-lubrication, impact strength, chemical resistance, appearance, and formability can be obtained from the composition of the present invention.

[0048] "Ethylene-based polymer composition (AII)" The preferred ethylene polymer composition (AII) is an ethylene polymer (a3) ​​with an limiting viscosity [η] of 0.1~2.9 dl / g.

[0049] Examples of the aforementioned ethylene-based polymers (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, ethylene-vinyl acetate copolymer saponifications, ethylene-(meth)acrylic acid copolymers, and ethylene-α-olefin-diene (triene, polyene) terpolymers. Among these, examples of α-olefins include: propylene (3-20 carbon atoms), 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Furthermore, examples of dienes (trienes, polyenes) include conjugated or non-conjugated dienes, trienes, polyenes, 5-ethylidene-2-norethene, vinylnorethene, etc.

[0050] The aforementioned ethylene polymer component (AII) can be a single ethylene polymer (a3), or a composition of two or more ethylene polymers (a3), or a composition of ethylene polymer (a3) ​​and polyolefins (polypropylene, polybutene, etc.). Furthermore, the aforementioned ethylene polymer component (AII) can also be a wax.

[0051] The ethylene-based polymer (a3) ​​mentioned above is preferably high-density polyethylene (HDPE), low-density polyethylene (LDPE), and more preferably high-density polyethylene (HDPE).

[0052] The density of the above-mentioned ethylene polymer (a3) ​​(determined according to ASTM D1505) is typically 820~980 kg / m3, preferably 930~980 kg / m3, and even more preferably 950~980 kg / m3.

[0053] The limiting viscosity [η] of the above-mentioned ethylene polymer (a3) ​​is typically 0.1~2.9 dl / g, preferably 0.3~2.8 dl / g, even better 0.5~2.5 dl / g, and exceptionally good 1.0~2.5 dl / g.

[0054] Because the aforementioned ethylene polymer component (AII) contains the aforementioned ethylene polymer (a3), it can be well dispersed when mixed with the aforementioned ethylene polymer component (AI). That is, when the melt flow rate is adjusted using an extruder or the like, the dispersion state can be uniform by the fine dispersion of the ethylene polymer component (AII) and the low or high molecular weight ethylene polymers (a2) contained in the ethylene polymer component (AI). Therefore, by using ethylene polymer component (A) with both ethylene polymer component (AI) and ethylene polymer component (AII), molded articles with excellent wear resistance, self-lubrication, impact strength, chemical resistance, appearance, softness, and formability can be obtained.

[0055] The above-mentioned components (AII) may also contain additives commonly added to polyolefins (e.g., heat stabilizers, weather stabilizers, etc.; crosslinking agents, crosslinking aids, antistatic agents, lubricants, anti-blocking agents, anti-fogging agents, slip agents, dyes, mineral oil-based softeners, petroleum resins, waxes, etc.). The composition of the present invention may also contain additives added to the above-mentioned components (AII) to the extent that it does not impair the effects of the present invention.

[0056] <Carbon Fiber (B)> The aforementioned carbon fiber (B) is not particularly limited and can be any known type of carbon fiber, such as: polyacrylonitrile-based, rayon-based, pitch-based, polyvinyl alcohol-based, regenerated cellulose-based, and pitch-based carbon fibers made from mesophase pitch. One of these systems can be used alone, or two or more can be used in combination.

[0057] The aforementioned carbon fiber (B) can be a general-purpose fiber or a high-strength fiber. Furthermore, the aforementioned carbon fiber (B) can also be a long fiber, a short fiber, a short fiber, or a regenerated fiber.

[0058] The aforementioned carbon fiber (B) is preferably a surface-treated carbon fiber. The surface treatment method for carbon fiber can be any commonly used and known method, such as electrolytic surface treatment of the carbon fiber using acid or alkaline aqueous solutions to impart functional groups to the carbon fiber surface; or treatment using a sizing agent. Preferably, sizing treatment can be performed using, for example, olefin polymers, epoxy polymers, nylon polymers, and urethane polymers.

[0059] The average length (i.e., average fiber length) of the aforementioned carbon fiber (B) is preferably 0.1 mm or more and 15.0 mm or less, more preferably 0.3 mm or more and 13.0 mm or less, and particularly preferably 0.5 mm or more and 13.0 mm or less. If the average fiber length is above the lower limit mentioned above, there is a tendency to fully manifest the mechanical property reinforcement effect caused by the carbon fiber. If the average fiber length is below the upper limit mentioned above, there is a tendency to disperse the carbon fiber in the ethylene-based polymer composition, resulting in a good appearance of the molded article.

[0060] The average fiber length of the carbon fibers (B) extracted from the composition of the present invention is preferably 100 μm or more and 400 μm or less, more preferably 120 μm or more and 380 μm or less, and particularly preferably 150 μm or more and 360 μm or less. By ensuring that the average fiber length of the carbon fibers (B) extracted from the composition of the present invention is within the above-mentioned range, the processability during the fabrication of the molded article is good. On the other hand, if the average fiber length exceeds the above-mentioned range, the carbon fibers and resin are not easily and uniformly mixed during molding, which may lead to a decrease in the physical properties of the composition and the molded article.

[0061] Furthermore, in the carbon fibers (B) extracted from the composition of the present invention, the proportion of carbon fibers with a fiber length of 100 μm or more and 300 μm or less is preferably 30% or more, more preferably 35-99%, and especially preferably 40-98%. By ensuring that the proportion of carbon fibers with a fiber length of 100 μm or more and 300 μm or less is within the above range, a molded article with improved mechanical strength and excellent wear resistance can be obtained. The fiber length and average fiber length of the carbon fiber (B) extracted from the composition of the present invention can be obtained, for example, by the method described in the following examples.

[0062] The average diameter of the aforementioned carbon fiber (B) is preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 21 μm or less, and particularly preferably 1 μm or more and 19 μm or less. If the average diameter of the carbon fiber is above the lower limit mentioned above, the carbon fiber is less likely to break during molding, and the impact strength of the resulting molded article tends to be improved. If the average diameter of the carbon fiber is below the upper limit mentioned above, the appearance of the molded article is good, the aspect ratio of the carbon fiber is not reduced, and the mechanical properties of the molded article, such as rigidity and heat resistance, tend to be adequately reinforced.

[0063] In the composition of the present invention, if the content of the ethylene polymer component (A) is set to 100 parts by mass, the content of the carbon fiber (B) is 1 to 100 parts by mass, preferably 4 to 70 parts by mass, more preferably 7 to 65 parts by mass, particularly preferably 10 to 60 parts by mass, and even more preferably 20 to 60 parts by mass. If the content of the carbon fiber (B) is within the above range, the composition of the present invention has excellent formability, and a molded body with excellent rigidity, conductivity, wear resistance, and heat resistance can be obtained from the composition of the present invention.

[0064] Commercially available carbon fiber (B) products include: TENAX (HT P802 (polyolefin polymer sizing agent), HT C605 (nylon polymer sizing agent), HT C503 (urethane polymer sizing agent)) manufactured by Teijin Co., Ltd.; Torayca short fiber T008-006 (epoxy polymer sizing agent) manufactured by Toray Industries, Ltd.; and EX-1LC (epoxy polymer sizing agent) manufactured by Nippon Polymer Sangyo Co., Ltd., etc.

[0065] <Modified Olefin Polymers (C)> The composition of this invention may also contain modified olefin polymers (C). The modified olefin polymer (C) mentioned above uses a compatibilizer, for example, to improve the compatibility of the ethylene polymer component (A) with the carbon fiber (B).

[0066] The modified olefin polymer (C) mentioned above is not particularly limited, and may be, for example, an acid-modified product (e.g., maleic anhydride-modified product), an air oxide, or a styrene-modified product of a homopolymer or copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. Among these, it is preferred to be a modified product 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).

[0067] Examples of the aforementioned α-olefins (α-olefins with 3 to 12 carbon atoms or α-olefins with 4 to 12 carbon atoms) include: propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0068] The modified olefin polymer (C) is preferably a modified ethylene polymer. The above-mentioned modified olefin polymer (C) is more preferably a modified ethylene polymer (C11) obtained by grafting modification of the following ethylene polymer (C1) with unsaturated carboxylic acid or its derivatives.

[0069] The preferred density of the above-mentioned ethylene-based polymer (c1) is 930~975 kg / m³, and the melt flow rate (MFR) at 190°C and 2.16 kg load, as determined by ASTM D1238, is 0.1~10 g / 10 min, or the melt flow rate (MFR) at 190°C and 10 kg load, as determined by ASTM D1238, is 0.1~20 g / 10 min.

[0070] The optimal density of the ethylene-based polymer (C1) is 940–970 kg / m³. If the density is within this range, the ethylene-based polymer component (A) has high compatibility with the carbon fiber (B).

[0071] The melt flow rate of the ethylene polymer (C1) (according to ASTM D1238, 190℃, 2.16kg load) is preferably 0.2~8 g / 10 min, more preferably 0.5~6 g / 10 min, and exceptionally preferably 0.5~3 g / 10 min. The melt flow rate of the ethylene polymer (C1) (according to ASTM D1238, 190℃, 10kg load) is preferably 0.1~15 g / 10 min, more preferably 0.1~10 g / 10 min, and exceptionally preferably 0.1~8 g / 10 min. If the melt flow rate is within the above range, the compatibility between the ethylene polymer component (A) and the carbon fiber (B) is high.

[0072] The grafting amount of unsaturated carboxylic acids or their derivatives in the modified ethylene polymer (C11) is typically 0.01 to 10% by mass, preferably 0.02 to 10% by mass. If the grafting amount is within the above range, the compatibility between the ethylene polymer component (A) and the carbon fiber (B) is high.

[0073] Examples of unsaturated carboxylic acids or their derivatives include: (meth)acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, iconic acid, citrate, crotonic acid, isocrotonic acid, nadic acid (internal bicyclic [2.2.1]hept-5-ene-dicarboxylic acid), and their derivatives, such as: acid halides, amides, anhydrous forms, esters, etc. Specific examples of the aforementioned derivatives include, for instance, maleic anhydride, maleic acid anhydride, citrate anhydride, monomethyl maleic acid, dimethyl maleic acid, glycidyl maleic acid, methyl (meth)acrylate, ethyl (meth)acrylate, glycidyl (meth)acrylate, monoethyl maleic acid, diethyl maleic acid, monomethyl fumarate, dimethyl fumarate, monomethyl itanate, diethyl itanate, etc., as well as esters and half-esters. Among these, unsaturated dicarboxylic acids and their anhydrides are preferred, and maleic acid, nadic acid, and their anhydrides are more preferred.

[0074] The aforementioned modified ethylene polymer (C11) can be manufactured using various known methods. For example, it can be produced by dissolving the ethylene polymer in an organic solvent, then adding unsaturated carboxylic acids or their derivatives, and, if desired, free radical initiators such as organic peroxides, to the resulting solution, typically at a temperature of 60–350°C (preferably 80–190°C) for 0.5–15 hours (preferably 1–10 hours); or by using an extruder or similar solvent-free method, adding the ethylene polymer, unsaturated carboxylic acids or their derivatives, and, if desired, free radical initiators such as organic peroxides, typically at a temperature above the melting point of the ethylene polymer, preferably at 160–350°C for 0.5–10 minutes.

[0075] The unmodified ethylene-based polymerization system can be manufactured using known methods (such as high-pressure methods, or low-pressure methods using Ziegler-type Ti-based catalysts, Co-based catalysts, or metallocene-based catalysts).

[0076] The ethylene polymer (c1) may contain one type of ethylene polymer or two or more types of ethylene polymers. When the ethylene polymer (c1) contains two or more ethylene polymers, each of the two or more ethylene polymers satisfies the requirements of density and melt flow rate of the ethylene polymer (c1).

[0077] If the composition of the present invention contains the modified olefin polymer (C), and the content of the ethylene polymer component (A) is set to 100 parts by mass, then the content of the modified olefin polymer (C) 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 particularly preferably 0.5 to 7 parts by mass. If the content of the modified olefin polymer (C) is within the above range, then the ethylene polymer component (A) and the carbon fiber (B) can be well compatible.

[0078] <Any ingredient> In addition to the ethylene polymer components (A), carbon fiber (B), and modified olefin polymer (C) mentioned above, the ethylene polymer composition of the present invention may, as needed, contain inorganic fillers other than carbon fiber (B), heat stabilizers, weather stabilizers, ultraviolet absorbers, light stabilizers, waxes, lubricants, sliding agents, core agents, anti-blocking agents, antistatic agents, anti-fogging agents, dyes, dispersants, flame retardants, flame retardant additives, plasticizers, compatibilizers, etc., commonly used additives for polyolefins, or impact strength modifiers such as elastomers, and polymers such as polyamides, without compromising the effects of the present invention.

[0079] When the ethylene-based polymer composition of the present invention contains the above-mentioned additives or polymers, their content is not particularly limited and can be set to, for example, a range of 0.01 to 30% by mass.

[0080] The above-mentioned additives are preferably waxes. Examples of waxes include: polyethylene waxes (excluding those belonging to the above-mentioned ethylene polymer components (AII)) and polypropylene waxes.

[0081] If the ethylene polymer composition of the present invention contains wax, the aggregation of carbon fibers (B) in the ethylene polymer component (A) can be suppressed, thus making it easy to mix. It is believed that the carbon fibers (B) can be easily dispersed in the ethylene polymer component (A).

[0082] When the ethylene polymer composition of the present invention contains wax, the content of wax is preferably in the range of 0.01 to 10% by mass relative to the total amount of the composition.

[0083] The ethylene polymer composition of the present invention, according to JIS K 7210-1:2014, has a preferred MFR of 0.01~20 g / 10 min, and a more preferred MFR of 0.01~10 g / 10 min, determined at 190°C and 10 kg load.

[0084] <Method for manufacturing ethylene-based polymeric components> The ethylene-based polymer composition of the present invention is obtained by mixing the above-mentioned ethylene-based polymer component (A), the above-mentioned carbon fiber (B), any of the above-mentioned modified olefin polymer (C), and any of the above-mentioned components according to a conventional method (for example, by dry blending of each component), and then performing melt mixing using a single-shaft or bi-shaft extruder, extruding in strand form and then granulating into particles.

[0085] The carbon fiber (B) mentioned above can also be premixed with polymer components such as the ethylene polymer component (A) mentioned above, and then used according to the form of the masterbatch.

[0086] <molded body> The molding system of the present invention contains the above-mentioned ethylene-based polymer composition. The manufacturing method (molding method) of the molded article includes conventional polyolefin molding methods, such as: extrusion molding, injection molding, film molding, gas molding, blow molding, extrusion blow molding, injection blow molding, stamping, vacuum forming, powder molding, calendering, foaming molding, and other known thermoforming methods. Preferably, injection molding is used to process the above-mentioned ethylene-based polymer composition to obtain a molded article containing the above-mentioned ethylene-based polymer composition.

[0087] The molded body described above may be a molded body formed from the above-mentioned ethylene-based polymer composition, or it may be a molded body having a portion formed from the above-mentioned ethylene-based polymer composition, such as a surface layer.

[0088] In the molded article of the present invention, the proportion of carbon fibers (B) with a needle-like ratio of 1.5 or higher is preferably 30% or higher, more preferably 30-70%, particularly preferably 31-65%, and even more preferably 32-60%. By ensuring that the proportion of carbon fibers with a needle-like ratio of 1.5 or higher is within the above range, the mechanical strength of the molded article can be improved, and a molded article with excellent rigidity and fatigue resistance can be obtained. The proportion of carbon fibers with a needle-like ratio of 1.5 or higher is obtained according to the method described in the embodiments below.

[0089] The shrinkage rate of the molded article in both the length and width directions is preferably less than 2.0%, more preferably less than 1.5%, and particularly preferably 0.05 to 1.0%. The above shrinkage rates can be obtained according to the methods described in the embodiments below.

[0090] The flexural modulus of the molded article of the present invention is preferably 5000 MPa or higher, more preferably 6000~20000 MPa, and particularly preferably 7000~15000 MPa. The above-mentioned flexural modulus can be obtained according to the method described in the embodiments below.

[0091] In vibration fatigue testing (35 MPa), the molded article of the present invention exhibits a preferred number of repetitions of 1500 or more, a more preferred number of 2000 or more, and an even more preferred number of 5000 or more when the displacement is 8 mm. The higher the upper limit of the above repetitions, the better; therefore, there is no particular limitation, but a preferred number is 10 million, a more preferred number is 1 million, and an even more preferred number is 500,000. The above repetition numbers can be obtained according to the method described in the embodiments below.

[0092] Molded bodies can be used in a wide range of applications, including household goods for daily use and recreational purposes, as well as general industrial and commercial products. Specific examples of molded bodies include: components for home appliances, communication equipment, electrical components, electronic components, automotive components, other vehicle components, shipbuilding and aircraft materials, mechanical components, building materials, civil engineering components, agricultural materials, power tool components, food containers, films, sheets, and fibers.

[0093] The molded articles of this invention can be widely used in conventional polyethylene applications, especially in applications requiring such applications due to their excellent balance of wear resistance, rigidity, self-lubrication, impact strength, and sheet forming properties, such as: metal coatings (laminated materials) for steel pipes, wires, automotive sliding door rails, etc.; rubber coatings (laminated materials) for various rubbers such as pressure-resistant rubber tubes, automotive door gaskets, cleanroom door gaskets, automotive window strips, and automotive door and window waterproof strips; linings for hoppers, chutes, etc.; sliding materials such as gears, bearings, rollers, belt reels, various guide rails, elevator guide rails, and various protective pads, etc.

[0094] Because the molded body of the present invention also has excellent conductivity, it can suppress the charge of various mechanical components and sliding parts, making it very suitable for applications requiring conductivity and antistatic properties. [Example]

[0095] The present invention will now be described in more detail with reference to embodiments; however, the present invention is not limited to these embodiments.

[0096] [Determination Method] The measurement methods for the physical properties of the polymers used in the examples, etc., the compositions obtained according to the examples, etc., and the molded articles produced using the compositions are as follows.

[0097] [Limiting viscosity [η]] Measured in decalin at 135°C.

[0098] [Density] The density of the ethylene-based polymer component (A) is measured by the density gradient method according to ASTM D1505. The density of the composition obtained from the examples or comparative examples is measured in water at 23°C by the hydrostatic weighing method according to JIS Z8807:2012.

[0099] [Fiber analysis of carbon fiber (B) extracted from the ethylene-based polymer composition] [Pretreatment] The granular composition obtained from the examples or comparative examples is heated in an electric furnace at 500°C for 30 minutes in an atmospheric environment.

[0100] [Image analysis of carbon fiber (B)] A part of the ash obtained according to the pretreatment is taken out on a glass slide. After spreading with oil and covering with a cover glass, the specimen is set as the observation sample. Using the "Stereo Microscope SZX16" manufactured by Olympus Corporation, the reflected bright-field image of the above sample is observed at a lens magnification of 4 times. From the observation field of view, a field of view containing fibers of 100 μm or more is selected. After obtaining the image, it is analyzed using image analysis software ("Win ROOF 2018" manufactured by MITANI Corporation) to obtain the fiber length and fiber number of carbon fiber (B).

[0101] [Average fiber length of carbon fiber (B)] Based on the results obtained from the above image analysis, the average fiber length of the carbon fibers contained in the composition is calculated. [Ratio of carbon fiber (B) with fiber length of 100 - 300 μm] Based on the results obtained from the above image analysis, the ratio of the fibers with a fiber length of 100 - 300 μm among all the analyzed fibers is calculated.

[0102] [Orientation] [Production of ASTM D671 Type A test piece] The composition obtained from the examples or comparative examples was fed into the hopper of an EC-75SXIII molding machine manufactured by Shibaura Machinery Co., Ltd., and melted at 230°C. It was then injection molded into a mold to produce a plate-shaped ASTM D671 Type A test piece (molded body) with the shape shown in Figure 1. The mold temperature during injection molding was set to 30~50°C, the injection pressure to 90~110 MPa, and the holding pressure to 55~65 MPa.

[0103] <Preparation of Observational Samples> For the ASTM D671 Type A test piece (molded body) shown in the schematic diagram in Figure 1, firstly, it is cut in the same direction as the injection molding flow direction (injection molding direction), that is, along line AA in Figure 1, and the area of ​​the sample taken is cut out. Secondly, the area of ​​the sample taken is embedded in resin, the cut surface along line AA is ground, and then it is cut to the required thickness using a slicing machine. Finally, carbon vapor deposition is performed to prepare the sample for observation.

[0104] <Observation and Analysis> The prepared samples were examined using a Hitachi High Technology (SHIPPING) S-3700N scanning electron microscope at an accelerating voltage of 10kV and a magnification of 150x. The observation direction of the samples was as shown in Figure 1, with the ground surface of the cut portion of the molded body designated as the frontal direction. The image was taken with the observation surface as seen from this direction parallel to the long side of the photographic image. The image center was set at a depth of 0.7-0.8 mm from the surface (top) of the molded body.

[0105] After acquiring the image, it was analyzed using image analysis software (Win ROOF 2018, manufactured by MITANI Corporation). Carbon fibers (CFs) were extracted from the image binarization, and the needle ratio of all extracted CFs was calculated and averaged. The needle ratio was calculated from the absolute maximum length of the observed elliptical CF and the ratio of the absolute maximum length to the vertical diagonal length (absolute maximum length / diagonal length).

[0106] [Conductivity (surface resistivity, volume resistivity)] <Preparation of a test piece with a length of 120mm, a width of 130mm, and a thickness of 3mm> The composition obtained from the examples or comparative examples was fed into the hopper of an EC-75SXIII molding machine manufactured by Shibaura Machinery Co., Ltd., and melted at 230°C. The mixture was then injection molded into a mold to produce a test piece with a length of 120mm, a width of 130mm, and a thickness of 3mm. The mold temperature was set to 50~70°C, the injection pressure to 90~110MPa, and the holding pressure to 40~70MPa.

[0107] <Determination of Surface Resistivity and Volume Resistivity> Using a test piece with a length of 120mm × width of 130mm × thickness of 3mm, the surface resistivity and volume resistivity were measured using an ADC (digital ultra-high resistance / micro-ammeter 8340A) and the double-ring method under the conditions of 23℃, humidity: 50%, applied voltage: 500V, and applied time: 60 seconds.

[0108] In addition, for the surface resistivity below 1.0×10 7 in the above measurements, the measurements were performed according to JIS K7194:1994 using the "LORESTA-GX-MCP-T700 low resistance resistivity meter" manufactured by Nitto Seiko Analytical Technology Co., Ltd., under the conditions of applied current: 1mA, application time: 10 seconds, temperature: 23°C, and humidity: 50%.

[0109] [Heat resistance (heat distortion temperature, HDT)] According to ISO-75-1,2, the test piece is shaped as described in JIS K7162 1A, and the heat distortion temperature is determined. Here, the heat distortion temperature is determined for the case where the bending stress is set to 0.45 MPa (HDT 0.45 MPa) and the case where it is set to 1.80 MPa (HDT 1.80 MPa).

[0110] [Formability (forming shrinkage)] In the same manner as described above, test pieces with a length of 120 mm × width of 130 mm × thickness of 3 mm were produced by injection molding. The dimensions of the test pieces (lengths in the length and width directions) after 3 days of molding were calculated, and the dimensional changes relative to the mold dimensions (lengths in the length and width directions) were evaluated, and their formability was evaluated. Specifically, the molded body (test piece) after injection molding was taken out of the mold and left to stand at room temperature for 3 days. Then, the lengths of each side in the length and width directions of the test piece and the differences in the lengths of each side in the length and width directions of the injection mold were measured for the four sides. The percentage ratios relative to the differences in the mold side lengths were obtained for each of the four sides, and the average value of these percentages was set as the molding shrinkage rate. The molding shrinkage rate in the length direction was set as the shrinkage rate MD, and the molding shrinkage rate in the width direction was set as the shrinkage rate TD.

[0111] [Sliding property (coefficient of kinetic friction) and abrasion resistance (specific wear rate)] The test piece with a length of 120 mm × width of 130 mm × thickness of 3 mm produced in the same manner as described above was perforated to produce a test piece with a length of 30 mm × width of 30 mm × thickness of 3 mm. Using this test piece, according to JIS K7218 "Plastics - Method A for Sliding Wear Test", the coefficient of kinetic friction and the specific wear rate were measured using a Matsushita type friction and wear testing machine. The test conditions were set as follows: target material: S45C, speed: 50 cm / second, distance: 3 km, load: 15 kg, measurement ambient temperature: 23°C.

[0112] [Tensile fracture strength, tensile fracture elongation, and tensile elastic modulus] According to ISO 527-1,2, the test piece shape was formed into the shape described in JIS K7162 1A, and the tensile speed was set to 50 mm / min to obtain the tensile fracture strength and tensile fracture elongation. Also, according to ISO 527-1,2, the test piece shape was set to JIS K7162 1A, and the tensile speed was set to 1 mm / min to obtain the tensile elastic modulus.

[0113] [Flexural strength, flexural elastic modulus] <Production of JIS K7162 1A test piece> The composition obtained in the examples or comparative examples was put into the hopper of the "EC-75SXIII molding machine" manufactured by Shibaura Machine Co., Ltd., melted at 230 °C, and injection molded into a mold to produce JIS K7162 1A test pieces. The mold temperature was set at 50 - 70 °C, the injection pressure was set at 80 - 120 MPa, and the holding pressure was set at 60 - 90 MPa. However, only when the composition obtained in Comparative Example 1 was used, the injection pressure was changed to 70 - 90 MPa and the holding pressure was changed to 25 - 45 MPa.

[0114] <Measurement of flexural strength and flexural modulus of elasticity> Using the JIS K7162 1A test pieces, according to ISO 178, the shape of the above test pieces was set to 80 mm (length), 10 mm (width), and 4 mm (thickness), and the flexural strength and flexural modulus of elasticity were obtained at a span distance of 64 mm and a test speed of 2 mm / min.

[0115] [Flexural fatigue test] <Production of ASTM D671 Type A test pieces> The composition obtained in the examples or comparative examples was put into the hopper of the "EC-75SXIII molding machine" manufactured by Shibaura Machine Co., Ltd., melted at 230 °C, and injection molded into a mold to produce ASTM D671 Type A test pieces. The mold temperature was set at 30 - 50 °C, the injection pressure was set at 90 - 110 MPa, and the holding pressure was set at 55 - 65 MPa.

[0116] <Measurement of vibration fatigue life> The ASTM D671 Type A test pieces were installed in the "B70 type repetitive vibration fatigue testing machine" manufactured by Toyo Seiki Seisaku-sho, Ltd., and a vibration fatigue test was carried out at room temperature, a frequency of 30 Hz, and a pressure of 35 MPa. The number of repetitions when the displacement was 8 mm was obtained and set as the fatigue resistance (times).

[0117] [Raw materials] The raw materials used in the examples or comparative examples are as follows.

[0118] (Ethylene-based polymer component (AI)) 《Manufacture of ethylene-based polymer component (AI-1)》 Using conventional methods, a high molecular weight ethylene polymer (polymer (a1)) with an ultimate viscosity of 30 dl / g is generated by polymerization in the first stage. Then, a low molecular weight ethylene polymer (polymer (a2)) with an ultimate viscosity of 1.5 dl / g is generated by polymerization in the second stage. The ethylene polymer component (AI-1) with an ultimate viscosity of 4.4 dl / g is obtained by two-stage polymerization with a mass ratio of 41 / 59 for polymer (a1) / polymer (a2).

[0119] Manufacturing of ethylene-based polymer components (AI-2) Using conventional methods, a high molecular weight ethylene polymer (polymer (a1)) with an ultimate viscosity of 30 dl / g is generated by polymerization in the first stage. Then, a low molecular weight ethylene polymer (polymer (a2)) with an ultimate viscosity of 1.5 dl / g is generated by polymerization in the second stage. The ethylene polymer component (AI-2) with an ultimate viscosity of 6.9 dl / g is obtained by two-stage polymerization with a mass ratio of 75 / 25 (polymer (a1) / polymer (a2)).

[0120] (Ethylene-based polymer composition (AII)) Use the following ethylene-based polymer components. Ethylene-based polymer composition (AII-1): High-density low molecular weight polyethylene (HI-ZEX 1700J) with an limiting viscosity [η] of 1.1 dl / g and a density of 965 kg / m³.

[0121] (Ethylene-based polymer composition (A)) Manufacturing of Ethylene-based Polymer Component (A-1) Ethylene-based polymer components (AI-1) and (AII-1) were blended at a mass ratio of 49 / 51 ((AI-1) / (AII-1)), and melt blending was performed using a Chibei Iron Works PCM twin-shaft extruder to obtain ethylene-based polymer component (A-1) with a granular limiting viscosity [η] of 3.0 dl / g and a density of 968 kg / m³. The content of ultra-high molecular weight ethylene-based polymer (polymer (a1)) in ethylene-based polymer component (A-1) was 20% by mass.

[0122] Manufacturing of Ethylene-based Polymer Component (A-2) Ethylene-based polymer component (AI-2) and ethylene-based polymer component (AII-1) were blended at a mass ratio of 33 / 67 ((AI-2) / (AII-1)). Melt blending was performed using a Chibei Iron Works PCM twin-shaft extruder to obtain ethylene-based polymer component (A-2) with a granular limiting viscosity [η] of 5.8 dl / g and a density of 966 kg / m³. The content of ultra-high molecular weight ethylene-based polymer (polymer (a1)) in ethylene-based polymer component (A-2) was 25% by mass.

[0123] (Carbon fiber (B)) Use the following carbon fiber. Carbon fiber (B-1): "TENAX HT P802" manufactured by Teijin Co., Ltd. (treated with polyolefin polymer sizing agent, fiber length: 3mm, diameter: 7μm, carbon fiber content: 98% by mass) Carbon fiber (B-2): "TENAX HT C605" manufactured by Teijin Co., Ltd. (treated with nylon-based polymer sizing agent, fiber length: 6mm, diameter: 7μm, carbon fiber content: 95.5% by mass) Carbon fiber (B-3): Toray Industries, Inc. "TORAYCA T008-006" (Epoxy polymer sizing agent treatment, fiber length: 6mm, diameter: 7μm, carbon fiber percentage: 99% by mass)

[0124] (Other carbon-based fillers) Use the following carbon nanotubes. Carbon nanotubes: NANOCYL "NC7000" (average diameter: 9.5nm, average length: 1.5μm)

[0125] Production of Carbon Nanotube Masterbatch The above-mentioned carbon nanotubes (15% by mass), ethylene polymer component (A-1) (75% by mass), and wax (polyethylene wax) (10% by mass) are mixed using existing methods to prepare a masterbatch containing carbon nanotubes.

[0126] (Modified olefin polymer (C)) The following modified olefin polymers are used as compatibilizers. Modified olefin polymer (C-1): Maleic acid modified ethylene polymer (density: 965 kg / m³, MFR (190°C, 2.16 kg load): 5 g / 10 min, degree of modification: 2.4) was manufactured according to the manufacturing method of ethylene polymer PE-0 described in International Publication No. 2019 / 208169, paragraphs

[0042] to

[0043] . Modified olefin polymer (C-2): A maleic acid modified ethylene polymer (density 967 kg / m³, limiting viscosity [η] 5 dl / g[η], MFR (190℃, 10 kgf): 6.2, degree of modification: 0.8) was manufactured according to the method for manufacturing modified polyolefin composition described in paragraph

[0083] of Japanese Patent Application Publication No. 2019-218568.

[0127] [Example 1] Dry blending was performed using 78% by mass of ethylene-based polymer (A-1), 20% by mass of carbon fiber (B-1), and 2% by mass of modified olefin polymer (C-1). The resulting product was then melt-extruded using a PARKER CORPORATION Co., Ltd. twin-shaft compounding extruder "HK-25D" at a barrel temperature of 260°C, a screw speed of 200 rpm, and an output rate of 12 kg / h. The blending amounts of each component in the obtained product (with the total amount of ethylene-based polymer set at 100 parts by mass) are shown in Table 1. Furthermore, the physical properties of the obtained product were measured according to the above method. The results are shown in Table 1.

[0128] [Example 2] Except for the proportions of the ethylene-based polymer (A-1), carbon fiber (B-1), and modified olefin polymer (C-1) as shown in Table 1, the compositions were prepared in the same manner as in Example 1, and their physical properties were measured. The results are shown in Table 1.

[0129] [Example 3] Except for replacing the modified olefin polymer (C-1) with modified olefin polymer (C-2), and adjusting the blending amounts as shown in Table 1 according to the amounts of ethylene polymer (A-1), carbon fiber (B-1), and modified olefin polymer (C-2), the composition was prepared in the same manner as in Example 1, and its physical properties were measured. The results are shown in Table 1.

[0130] [Example 4] Except for replacing the ethylene-based polymer component (A-1) with ethylene-based polymer component (A-2), and adjusting the blending amounts of ethylene-based polymer component (A-2), carbon fiber (B-1), and modified olefin polymer component (C-1) as shown in Table 1, the composition was prepared in the same manner as in Example 1, and its physical properties were measured. The results are shown in Table 1.

[0131] [Example 5] Except for replacing carbon fiber (B-1) with carbon fiber (B-2) and adjusting the blending amounts as shown in Table 1 according to the amounts of ethylene-based polymer (A-1), carbon fiber (B-2), and modified olefin-based polymer (C-1), the other components were prepared in the same manner as in Example 1, and their physical properties were measured. The results are shown in Table 1.

[0132] [Example 6] Except for replacing carbon fiber (B-1) with carbon fiber (B-3) and adjusting the blending amounts as shown in Table 1 according to the amounts of ethylene-based polymer (A-1), carbon fiber (B-3), and modified olefin-based polymer (C-1), the other components were prepared in the same manner as in Example 1, and their physical properties were measured. The results are shown in Table 1.

[0133] [Comparative Example 1] Except for replacing the ethylene-based polymer component (A-1) with ethylene-based polymer component (AII-1), and adjusting the blending amounts of ethylene-based polymer component (AII-1), carbon fiber (B-1), and modified olefin polymer component (C-1) as shown in Table 1, the composition was prepared in the same manner as in Example 1, and its physical properties were measured. The results are shown in Table 1.

[0134] [Comparative Example 2] Except for the absence of carbon fiber (B-1) and modified olefin polymer (C-1), and the use of only ethylene polymer component (A-1), the compositions were prepared in the same manner as in Example 1, and their physical properties were measured. The results are shown in Table 1.

[0135] [Comparative Example 3] Dry blending of 40% by mass of ethylene-based polymer component (A-2) and 60% by mass of carbon nanotube masterbatch was performed. The resulting compound was then melt-extruded using a PARKER CORPORATION Co., Ltd. twin-shaft compounding extruder "HK-25D" at a barrel temperature of 260°C, a screw speed of 200 rpm, and an output rate of 12 kg / h. The blending amounts of each component in the obtained compound (with the total amount of the ethylene-based polymer set at 100 parts by mass) are shown in Table 1. Furthermore, the physical properties of the obtained compound were measured according to the above method. The results are shown in Table 1.

[0136] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 formula Components of ethylene-based polymers (A) type Al Al Al A-2 Al Al AII-1 Al A-2 kg / m 3 968 968 968 966 968 968 965 968 968 Quality 100 100 100 100 100 100 100 100 100 Carbon fiber (B) type Bl Bl Bl Bl B-2 B-3 Bl - - Quality 25.1 43.2 25.1 25.1 24.5 25.4 25.1 - - carbon nanotubes Quality - - - - - - - - 10.6 wax Quality 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7.1 Modified olefin polymers (C) type Cl Cl C-2 Cl Cl Cl Cl - - Quality 2.6 2.9 2.6 2.6 2.6 2.6 2.6 - - physical properties density Composition density kg / m 3 1020 1040 1050 1020 1040 1020 1040 960 1000 fiber Average fiber length μm 330 201 315 267 332 271 300 ND <100 The ratio of 100 to 300 μm % 46 91 52 68 48 64 61 ND 0 Alignment The ratio of needle-like structures to 1.5 is considered a proportion. % 45.2 32.8 44.5 52.5 40.4 58.2 51.3 ND 0 electrical conductivity Surface resistivity Ω / cm 8.7E+02 3.1E+01 1.1E+03 6.3E+02 3.8E+03 4.2E+04 8.1E+01 9.7E+16 5.7E+06 Volume resistivity Ω·cm 2.6E+02 9.0E+00 3.3E+02 1.9E+02 1.1E+03 1.3E+04 2.4E+01 2.1E+17 2.9E+03 Heat resistance HDT 0.45MPa °C 129 130 129 129 129 127 130 77 78 HDT 1.80MPa °C 116 120 116 115 114 105 123 50 51 Formability Shrinkage rate MD % 0.29 0.18 0.27 0.3 0.32 0.48 0.16 2.9 2.7 Shrinkage rate TD % 0.13 0.22 0.13 0.14 0.17 0.22 0.16 1.9 2.2 Sliding coefficient of kinetic friction μd 0.20 0.17 0.22 0.22 0.22 0.33 0.20 0.17 0.19 abrasion resistance Specific wear 10^-3 mm³ / kgf·km 56 32 32 20 60 80 320 220 110 rigidity Tensile breaking strength MPa 66 70 70 60 60 60 75 30 40 Elongation at break % 1.4 1.2 1.5 1.3 1.2 1.6 1.6 19 12 tensile modulus MPa 9099 12336 9404 9145 9080 7690 11402 1241 1585 Bending strength MPa 90 100 90 90 85 80 100 30 40 Flexural modulus MPa 10150 14500 10000 10600 10400 8800 11100 130 1770 Fatigue resistance Vibration fatigue cycles Second-rate 5520 159000 11110 12500 2000 1500 28000 <1000 <1000

Claims

1. An ethylene-based polymer composition comprising: 100 parts by mass of an ethylene-based polymer component (A) having an limiting viscosity [η] of 1.5~10 dl / g and a density of 930~980 kg / m3 as determined in a solvent of decahydronaphthalene at 135°C; and 1~100 parts by mass of carbon fiber (B); wherein, The above-mentioned ethylene polymer component (A) contains an ultra-high molecular weight ethylene polymer (a1) with an ultimate viscosity [η] of 10~40 dl / g as measured in decahydronaphthalene solvent at 135°C; the carbon fibers (B) extracted from the above-mentioned ethylene polymer component have an average fiber length of 100 μm or more and 400 μm or less.

2. As in claim 1, an ethylene-based polymer composition, wherein, The above-mentioned ethylene polymer component (A) contains: a low or high molecular weight ethylene polymer (a2) with a limiting viscosity [η] of 0.1~9 dl / g as measured in decahydronaphthalene solvent at 135°C.

3. As in claim 2, an ethylene-based polymer composition, wherein, The aforementioned ethylene polymer component (A) comprises: 10-90% by mass of ethylene polymer component (AI) and 90-10% by mass of ethylene polymer component (AII) (the total mass of components (AI) and (AII) is set to 100% by mass); the aforementioned ethylene polymer component (AI) is a multi-segment polymer composed of: more than 35% by mass and less than 90% by mass of the aforementioned ultra-high molecular weight ethylene polymer (a1) and more than 10% by mass and less than 65% by mass of the aforementioned low molecular weight or high molecular weight ethylene polymer (a2) (the total mass of polymer (a1) and polymer (a2) is set to 100% by mass); the aforementioned ethylene polymer component (AII) comprises: ethylene polymer (a3) ​​with an ultimate viscosity [η] of 0.1-2.9 dl / g as determined in decahydronaphthalene solvent at 135°C.

4. As in claim 3, an ethylene-based polymer composition, wherein, The aforementioned ethylene polymer component (AI) is obtained by a multi-stage polymerization method including the steps of generating the aforementioned ultra-high molecular weight ethylene polymer (a1) and generating the aforementioned low molecular weight or high molecular weight ethylene polymer (a2).

5. An ethylene-based polymer composition as described in any of claims 1 to 4, wherein, The carbon fiber (B) mentioned above is a surface-treated carbon fiber.

6. As in claim 5, an ethylene-based polymer composition, wherein, The surface treatment of the carbon fiber (B) mentioned above is a sizing treatment using olefin polymers, urethane polymers, nylon polymers, or epoxy polymers.

7. An ethylene-based polymer composition as described in any of claims 1 to 4, wherein, The carbon fibers (B) extracted from the above-mentioned ethylene-based polymer composition contain 30% or more carbon fibers with a length of 100 μm or more and 300 μm or less.

8. An ethylene-based polymer composition as described in any of claims 1 to 4, wherein, Contains modified olefin polymers (C).

9. An ethylene-based polymer composition as described in any of claims 1 to 4, wherein, The content of carbon fiber (B) is 20 to 60 parts by mass relative to 100 parts by mass of the ethylene polymer component (A) mentioned above.

10. A molded article comprising an ethylene-based polymer composition according to any one of claims 1 to 9.

11. The shaped body as claimed in claim 10, wherein, In the above-mentioned molded body, the proportion of carbon fibers (B) with a needle-like ratio of 1.5 or more is 30% or more.

12. The shaped body as claimed in claim 10 or 11, wherein, The shrinkage rates in both the length and width directions of the above-mentioned molded body are less than 2.0%.

13. The shaped body as claimed in claim 10 or 11, wherein, The flexural modulus of the above-mentioned molded body is above 5000 MPa.

14. The shaped body as claimed in claim 10 or 11, wherein, In the vibration fatigue test (35MPa), the above-mentioned molded body was repeated more than 1500 times when the displacement was 8mm.

15. The molded body as requested in item 10 or 11 is an injection molded body.

16. The molded body as requested in item 10 or 11 is a covered material or a sliding material.

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