ETHYLENE-BASED POLYMER COMPOSITION AND USE APPLICATIONS THEREOF

Abstract

An object of the present invention is to obtain an ethylene-based polymer composition useful as a material for shaped articles having a low surface resistivity and a low volume resistivity and exhibiting excellent slidability. The present invention pertains to an ethylene-based polymer composition containing an ethylene-based polymer (A) and a carbon-based filler (C), the ethylene-based polymer composition having a melt flow rate (MFR) in the range of 0.1 to 20 g/10 min as measured in accordance with JIS K7210-1: 2014 at a measurement temperature of 230° C. under a load of 10 kgf.

Claims

1. An ethylene-based polymer composition comprising an ethylene-based polymer (A) and a carbon-based filler (C), the ethylene-based polymer composition having a melt flow rate (MFR) in the range of 0.1 to 20 g/10 min as measured in accordance with JIS K7210-1: 2014 at a measurement temperature of 230° C. under a load of 10 kgf.

2. The ethylene-based polymer composition according to claim 1, wherein the content of the ethylene-based polymer (A) is 70 to 99.9 mass %, and the content of the carbon-based filler (C) is 0.1 to 30 mass % [where the total of (A)+(C) is 100 mass %].

3. The ethylene-based polymer composition according to claim 1, wherein the carbon-based filler (C) is carbon nanotube.

4. The ethylene-based polymer composition according to claim 1, wherein the ethylene-based polymer (A) comprises an ethylene-based polymer having an intrinsic viscosity [η] in the range of 10 to 40 dl/g.

5. The ethylene-based polymer composition according to claim 1, wherein the ethylene-based polymer (A) is an ethylene-based polymer composition comprising an ethylene-based polymer composition (A-I) and an ethylene-based polymer composition (A-II); wherein the ethylene-based polymer composition contains 10 to 90 mass % of the ethylene-based polymer composition (A-I) and 90 to 10 mass % of the ethylene-based polymer composition (A-II) [where the total of (A-I)+(A-II) is 100 mass %]; wherein the ethylene-based polymer composition (A-I) is an ethylene polymer composition comprising: more than 35 mass % and 90 mass % or less of an ultrahigh-molecular weight ethylene-based polymer (a component (a-1)) having an intrinsic viscosity [η] of 10 to 40 dl/g, and 10 mass % or more and less than 65 mass % of a low-molecular weight to high-molecular weight ethylene-based polymer (a component (a-2)) having an intrinsic viscosity [η] of 0.1 to 9 dl/g, based on the total mass of the component (a-1) and the component (a-2); wherein the ethylene-based polymer composition (A-I) has a density of 930 to 980 kg/m.sup.3 and an intrinsic viscosity [η] of 3.0 to 10.0 dl/g; and wherein the ethylene-based polymer composition (A-II) comprises an ethylene (co)polymer having at least an intrinsic viscosity [η] of 0.1 to 2.9 dl/g.

6. The ethylene-based polymer composition according to claim 1, further comprising a polyamide in an amount of 30 mass % or less [relative to the total of (A)+(C)+polyamide taken as 100 mass %].

7. A shaped article comprising the ethylene-based polymer composition described in claim 1.

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

9. The shaped article according to claim 7, which is a covering material.

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

Description

EXAMPLES

[0093] Hereinbelow, the present invention will be described in greater detail based on Examples. However, it should be construed that the scope of the present invention is not limited to those Examples. In the description of the following Examples and other experiments, “parts” means “parts by mass” unless otherwise specified.

[0094] In Examples and Comparative Examples of the present invention, the following ethylene-based polymer (A) and the following carbon-based filler (C) were used.

(1) Ethylene-Based Polymer (A)

(1.1) Ethylene-Based Copolymer Composition (A-1)

[0095] An ethylene-based polymer composition (A-I-1) (intrinsic viscosity [η]: 4.4 dl/g) was provided that had been obtained by two-stage polymerization of an ultrahigh-molecular weight polyethylene (a component (a-1)) having an intrinsic viscosity [η] of 30 dl/g and a low-molecular weight polyethylene (a component (a-2)) having an intrinsic viscosity [η] of 1.5 dl/g in a mass ratio of 41/59. To the ethylene-based polymer composition (A-I-1) was added a high-density low-molecular weight polyethylene having an intrinsic viscosity [η] of 1.1 dl/g and a density of 965 kg/m.sup.3 (produce name: HI-ZEX 1700JP, manufactured by Prime Polymer Co., Ltd.) as an ethylene-based polymer composition (A-II-1) in a mass ratio of 49/51 so that the concentration of the ultrahigh-molecular weight polyethylene (the component (a-1)) in an ethylene-based polymer composition (A-1) would be 20 mass %. The resulting mixture was melt-blended using twin-screw extruder PCM manufactured by Ikegai Corp. Pellets of an ethylene-based copolymer composition (A-1) were thus obtained.

[0096] The ethylene-based copolymer composition (A-1) with an intrinsic viscosity [η] of 3.0 dl/g that was obtained by the above production method was used as an ethylene-based polymer (A).

(1.2) Ethylene-Based Copolymer (B-1)

[0097] A high-density low-molecular weight polyethylene having an intrinsic viscosity [η] of 1.1 dl/g and a density of 965 kg/m.sup.3 (produce name: HI-ZEX 1700J, manufactured by Prime Polymer Co., Ltd.) was used.

(2) Carbon-Based Filler (C)

(2.1) Carbon-Based Filler (C-1)

[0098] Carbon nanotubes, produce name: Carbon nanotubes NC7000, manufactured by Nanocyl SA., were used as a carbon-based filler (C-1). The carbon nanotubes had an average diameter of 9.5 nm and an average length of 1.5 μm.

(2.2) Preparation of Carbon-Based Filler (C-1)-Containing Masterbatch (1)

[0099] 15 mass % of the carbon-based filler (C-1), 75 mass % of the ethylene-based copolymer composition (A-1) and 10 mass % of a wax were mixed together to give a masterbatch (1).

(2.3) Preparation of Carbon-Based Filler (C-1)-Containing Masterbatch (2)

[0100] 15 mass % of the carbon-based filler (C-1), 75 mass % of the ethylene-based copolymer (B-1) and 10 mass % of a wax were mixed together to give a masterbatch (2).

[0101] Properties of the ethylene-based polymer composition were measured by the following methods.

[Method for Measuring Intrinsic Viscosity [η]]

[0102] In accordance with ASTM D4020, the ethylene-based polymer composition was dissolved into decalin, and the intrinsic viscosity measured at 135° C. was defined as [η].

[Method for Measuring Density]

[0103] The density of the ethylene-based copolymer composition before the addition of the carbon-based filler was measured by a density gradient method in accordance with ASTM D1505.

Example 1

[0104] The ethylene-based copolymer composition (A-1): 90 mass %, and the carbon-based filler (C-1)-containing masterbatch (1): 10 mass % were dry-blended. The resulting dry blend was added to a hopper of twin-screw extruder BT30 manufactured by Research Laboratory of Plastics Technology Co., Ltd., and was melt-kneaded at 230° C. to give pellets of an ethylene-based polymer composition.

[0105] The MFR of the ethylene-based polymer composition obtained was measured by the following method.

[0106] In accordance with JIS K7210-1: 2014, the melt flow rate (MFR) was measured at a measurement temperature of 230° C. under a load of 10 kgf to be 16.2 g/10 min.

[0107] The pellets of the ethylene-based polymer composition were added to a hopper of injection molding machine Toshiba 75 Ton manufactured by Toshiba Machine Co., Ltd. The pellets were melted at 230° C., and the melt was injection-molded into a 30° C. mold at an injection pressure of 90 MPa and a holding pressure of 75 MPa. A multipurpose test specimen Type-A conforming to ISO 3167: 93, and a 300 mm×300 mm×3 mm thick flat plate were thus fabricated.

[0108] Separately, a hydraulic hot press machine manufactured by Shinto Metal Industries, Ltd. was set at 230° C., and the pellets of the ethylene-based polymer composition were preheated for 8 minutes and were pressed at 10 MPa for 3 minutes. The sheet was transferred to another hydraulic press machine manufactured by Shinto Metal Industries, Ltd. that had been preset at 20° C., and was cold-pressed for 5 minutes. A 1 mm thick pressed sheet test specimen was thus prepared. A 5 mm thick brass plate was used as the hot plate.

[0109] Properties of the ethylene-based polymer composition obtained were measured by the following methods.

[0110] The results are described in Table 1.

[Density]

[0111] The density of the shaped article of the ethylene-based polymer composition was measured in water at 23° C. by a submerged weighing method in accordance with JIS 28807: 2012.

[Tensile Strength at Break and Tensile Elongation at Break]

[0112] A test specimen having a shape described in JIS K7162 1A was tested in accordance with ISO 527-1 and 2 at a stress rate of 50 mm/min to determine the tensile strength at break and the tensile elongation at break.

[Flexural Strength and Flexural Modulus]

[0113] In accordance with ISO 178, a test specimen 80 mm (in length), 10 mm (in width) and 4 mm (in thickness) was tested with a span distance of 64 mm at a test speed of 2 mm/min to determine the flexural strength and the flexural modulus.

[Dynamic Friction Coefficient and Specific Wear Rate]

[0114] In accordance with JIS K7218, “Testing Method A for Sliding Wear Resistance of Plastics”, the dynamic friction coefficient and the specific wear rate were measured with a Matsubara-type friction wear tester to evaluate the slidability and the wear resistance.

[0115] The testing conditions were mating material: S45C, speed: 50 cm/sec, distance: 3 km, load: 15 kg, and measurement environment temperature: 23° C.

[Surface Resistivity and Volume Resistivity]

[0116] The 1 mm thick pressed sheet of the ethylene-based polymer composition was tested with digital ultrahigh resistance/minute current electrometer 8340A manufactured by ADC CORPORATION by a guarded-electrode method at 23° C. under the conditions where humidity: 50%, applied voltage: 500 V, and application time: 60 seconds.

[0117] When the measurement of surface resistivity resulted in a level below 1.0×10.sup.7, measurement was performed in accordance with JIS K7194: 1994 using low resistivity meter Loresta-GX-MCP-T700 manufactured by Nittoseiko Analytech Co., Ltd. under the conditions where applied current: 1 mA, application time: 10 seconds, 23° C., and humidity: 50%.

Examples 2 and 3

[0118] An ethylene-based polymer composition was obtained in the same manner as in Example 1, except that the ethylene-based polymer composition used in Example 1 was replaced by an ethylene-based polymer composition prepared while changing the amounts of the ethylene-based copolymer composition (A-1) and the carbon-based filler (C-1)-containing masterbatch (1) as described in Table 1. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0119] The results are described in Table 1.

Example 4

[0120] An ethylene-based polymer composition was obtained in the same manner as in Example 1, except that the ethylene-based polymer composition used in Example 1 was replaced by an ethylene-based polymer composition prepared while changing the amounts of the ethylene-based copolymer composition (A-1) and the carbon-based filler (C-1)-containing masterbatch (1) as described in Table 1. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0121] The results are described in Table 1.

Example 5

[0122] The ethylene-based copolymer composition (A-1): 50 mass %, the carbon-based filler (C-1)-containing masterbatch (1): 40 mass %, and polyamide 6 (produce name: Amilan CM1007 manufactured by TORAY INDUSTRIES, INC.): 10 mass % were dry-blended. The resulting dry blend was added to a hopper of twin-screw extruder BT30 manufactured by Research Laboratory of Plastics Technology Co., Ltd., and was melt-kneaded at 240° C. to give pellets of an ethylene-based polymer composition.

[0123] The MFR of the ethylene-based polymer composition obtained was measured by the following method.

[0124] In accordance with JIS K7210-1: 2014, the melt flow rate (MFR) was measured at a measurement temperature of 230° C. under a load of 10 kgf to be 7.6 g/10 min.

[0125] Next, the pellets of the ethylene-based polymer composition were added to a hopper of injection molding machine Toshiba 75 Ton manufactured by Toshiba Machine Co., Ltd. The pellets were melted at 230° C., and the melt was injection-molded into a 30° C. mold at an injection pressure of 90 MPa and a holding pressure of 75 MPa. A multipurpose test specimen Type-A conforming to ISO 3167: 93, and a 300 mm×300 mm×3 mm thick flat plate were thus fabricated.

[0126] Separately, a hydraulic hot press machine manufactured by Shinto Metal Industries, Ltd. was set at 240° C., and the pellets of the ethylene-based polymer composition were preheated for 8 minutes and were pressed at 10 MPa for 3 minutes. The sheet was transferred to another hydraulic press machine manufactured by Shinto Metal Industries, Ltd. that had been preset at 20° C., and was cold-pressed for 5 minutes. A 1 mm thick pressed sheet test specimen was thus prepared. A 5 mm thick brass plate was used as the hot plate.

[0127] The results are described in Table 1.

Example 6

[0128] An ethylene-based polymer composition was obtained in the same manner as in Example 1, except that the ethylene-based copolymer composition (A-1): 40 mass %, the carbon-based filler (C-1)-containing masterbatch (1): 40 mass %, and the polyamide 6: 20 mass % were used. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0129] The results are described in Table 1.

Example 7

<Production of Modified Ethylene Polymer Composition>

[0130] The ethylene-based copolymer composition (A-1): 100 parts by mass, maleic anhydride: 0.8 parts by mass, and an organic peroxide [produce name: PERHEXYN-25B, manufactured by NOF CORPORATION]: 0.07 parts by mass were mixed together in a Henschel mixer. The resulting mixture was subjected to melt graft modification in a 65 mm-diameter single-screw extruder that had been preset at 250° C. A modified ethylene-based copolymer composition was thus obtained. The amount of maleic anhydride grafts in the modified polyolefin composition obtained was measured by IR analysis to be 0.8 mass %.

<Production of Ethylene-Based Polymer Composition>

[0131] The ethylene-based copolymer composition (A-1): 38 mass %, the modified ethylene-based copolymer composition: 2 mass %, the carbon-based filler (C-1)-containing masterbatch (1): 40 mass %, and the polyamide 6: 20 mass % were dry-blended in the same manner as in Example 1 to give an ethylene-based polymer composition. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0132] The results are described in Table 1.

Example 8

[0133] The ethylene-based copolymer composition (A-1): 40 mass %, and the carbon-based filler (C-1)-containing masterbatch (1): 60 mass % were dry-blended. The resulting dry blend was added to a hopper of twin-screw extruder BT30 manufactured by Research Laboratory of Plastics Technology Co., Ltd., and was melt-kneaded at 250° C. to give pellets of an ethylene-based polymer composition. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

Comparative Example 1

[0134] An ethylene-based polymer composition was obtained in the same manner as in Example 1, except that the ethylene-based polymer composition used in Example 1 was replaced by an ethylene-based polymer composition free from the carbon-based filler (C-1)-containing masterbatch (1). The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0135] The results are described in Table 1.

Comparative Example 2

[0136] The ethylene-based copolymer composition (A-1): 80 mass %, and the carbon-based filler (C-1)-containing masterbatch (2): 20 mass % were dry-blended. The resulting dry blend was added to a hopper of twin-screw extruder BT30 manufactured by Research Laboratory of Plastics Technology Co., Ltd., and was melt-kneaded at 230° C. to give pellets of an ethylene-based polymer composition. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0137] The results are described in Table 1.

Comparative Example 3

[0138] The ethylene-based copolymer (B-1): 80 mass %, and the carbon-based filler (C-1)-containing masterbatch (2): 20 mass % were dry-blended. The resulting dry blend was added to a hopper of twin-screw extruder BT30 manufactured by Research Laboratory of Plastics Technology Co., Ltd., and was melt-kneaded at 200° C. to give pellets of an ethylene-based polymer composition. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0139] The results are described in Table 1.

Comparative Example 4

[0140] An ethylene-based polymer composition was obtained in the same manner as in Comparative Example 3, except that the ethylene-based polymer composition used in Comparative Example 3 was replaced by an ethylene-based polymer composition prepared while changing the amounts of the ethylene-based copolymer (B-1) and the carbon-based filler (C-1)-containing masterbatch (2) as described in Table 1. The ethylene-based polymer composition obtained was evaluated by the same methods as in Example 1.

[0141] The results are described in Table 1.

TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ethylene-based copolymer mass % 90 80 40 60 composition (A-1) Ethylene-based copolymer mass % (B-1) Carbon-based filler (C-1)— mass % 10 20 60 40 containing masterbatch (1) Carbon-based filler (C-1)— mass % containing masterbatch (2) Polyamide 6 mass % Modified ethylene-based mass % copolymer composition Content of ethylene-based mass % 98.5 96.9 90.4 93.8 copolymer composition (A-1) relative to the total of ethylene- based copolymer composition (A-1) and carbon-based filler (C-1) taken as 100 mass % Content of carbon-based filler mass % 1.5 3.1 9.6 6.2 (C-1) relative to the total of ethylene-based copolymer composition (A-1) and carbon- based filler (C-1) taken as 100 mass % Content of ethylene-based mass % 97.5 95 85 90 copolymer composition (A-1) in ethylene-based polymer composition Content of carbon-based filler mass % 1.5 3 9 6 (C-1) in ethylene-based polymer composition MFR g/10 min 16.2 12.6 8.38 10.2 Density kg/m.sup.2 968 974 1002 988 Tensile strength at break MPa 32.7 34 36.1 35 Tensile elongation at break % 13.5 12.9 12.2 12.9 Flexural strength MPa 54.5 56 58.7 58 Flexural modulus MPa 1543 1589 1660 1638 Dynamic friction coefficient - 0.13 0.13 0.26 0.19 Specific wear rate 10.sup.−3 mm.sup.3/ 258 210 117 148 kg km Surface resistivity Ω/cm 7.1 × 10{circumflex over ( )}11 2.5 × 10{circumflex over ( )}14 4.1 × 10{circumflex over ( )}2 2.7 × 10{circumflex over ( )}3 Volume resistivity Ω .Math. cm 4.6 × 10{circumflex over ( )}16 1.5 × 10{circumflex over ( )}15 4.7 × 10{circumflex over ( )}1 3.0 × 10{circumflex over ( )}2 Comp. Ex. 1 Ex. 5 Ex. 6 Ex. 7 Ethylene-based copolymer mass % 100 50 40 38 composition (A-1) Ethylene-based copolymer mass % (B-1) Carbon-based filler (C-1)- mass % 0 40 40 40 containing masterbatch (1) Carbon-based filler (C-1)- mass % containing masterbatch (2) Polyamide 6 mass % 10 20 20 Modified ethylene-based mass % 2 copolymer composition Content of ethylene-based mass % 100 93.3 92.5 90 copolymer composition (A-1) relative to the total of ethylene- based copolymer composition (A-1) and carbon-based filler (C-1) taken as 100 mass % Content of carbon-based filler mass % 0 6.7 7.5 7.5 (C-1) relative to the total of ethylene-based copolymer composition (A-1) and carbon- based filler (C-1) taken as 100 mass % Content of ethylene-based mass % 100 90 90 90 copolymer composition (A-1) in ethylene-based polymer composition Content of carbon-based filler mass % 0 6 6 6 (C-1) in ethylene-based polymer composition MFR g/10 min 22 7.6 9.7 13.1 Density kg/m.sup.2 961 1000 1022 1018 Tensile strength at break MPa 27.5 45 33 35 Tensile elongation at break % 18.8 6.9 8.2 5.7 Flexural strength MPa 49.6 45 39 40 Flexural modulus MPa 1370 1880 1380 1610 Dynamic friction coefficient - 0.17 0.2 0.22 0.19 Specific wear rate 10.sup.−3 mm.sup.3/ 218 77 139 100 kg km Surface resistivity Ω/cm 9.7 × 10{circumflex over ( )}16 4.0 × 10{circumflex over ( )}2 7.3 × 10{circumflex over ( )}1 2.0 × 10{circumflex over ( )}2 Volume resistivity Ω .Math. cm 6.8 × 10{circumflex over ( )}16 2.0 × 10{circumflex over ( )}1 2.0 × 10{circumflex over ( )}0 2.0 × 10{circumflex over ( )}1 Ex. 8 Comp. Ex. 2 Comp. Ex.3 Comp. Ex. 4 Ethylene-based copolymer mass % 40 80 composition (A-1) Ethylene-based copolymer mass % 80 60 (B-1) Carbon-based filler (C-1)- mass % 60 containing masterbatch (1) Carbon-based filler (C-1)- mass % 20 20 40 containing masterbatch (2) Polyamide 6 mass % Modified ethylene-based mass % copolymer composition Content of ethylene-based mass % 90.4 96.3 0 0 copolymer composition (A-1) relative to the total of ethylene- based copolymer composition (A-1) and carbon-based filler (C-1) taken as 100 mass % Content of carbon-based filler mass % 9.6 3.6 100 100 (C-1) relative to the total of ethylene-based copolymer composition (A-1) and carbon- based filler (C-1) taken as 100 mass % Content of ethylene-based mass % 85 83 0 0 copolymer composition (A-1) in ethylene-based polymer composition Content of carbon-based filler mass % 9 3 3 6 (C-1) in ethylene-based polymer composition MFR g/10 min 2 27.2 230 80.8 Density kg/m.sup.2 1005 1000 980 995 Tensile strength at break MPa 37 33 31 25 Tensile elongation at break % 11 13 14.7 22.1 Flexural strength MPa 39 36 30 31 Flexural modulus MPa 1810 1560 1390 1444 Dynamic friction coefficient - 0.2 0.21 0.2 0.22 Specific wear rate 10.sup.−3 mm.sup.3/ 199 1400 1600 4550 kg km Surface resistivity Ω/cm 1.1 × 10{circumflex over ( )}1 2.5 × 10{circumflex over ( )}15 1.5 × 10{circumflex over ( )}14 2.5 × 10{circumflex over ( )}1 Volume resistivity Ω .Math. cm 2.9 × 10{circumflex over ( )}1 8.3 × 10{circumflex over ( )}14 9.4 × 10{circumflex over ( )}13 2.5 × 10{circumflex over ( )}1