VIBRATIONPROOF RUBBER COMPOSITION, VULCANIZED MOLDED BODY, AND VIBRATIONPROOF RUBBER

Abstract

A vibrationproof rubber composition capable of obtaining a vibrationproof rubber having a specific hardness and an excellent balance of mechanical properties, vibrationproof properties, and a friction coefficient, a vulcanized molded body obtained by vulcanizing the vibrationproof rubber composition, and vibrationproof rubber is provided. A vibrationproof rubber composition comprising: 100 parts by mass of xanthogen-modified chloroprene rubber; 0.5 to 2 parts by mass of stearic acid amide; and 4 to 5 parts by mass of erucic acid amide, wherein: the vibrationproof rubber composition further comprises carbon black with an average primary particle diameter of 60 to 470 nm, and a molded body obtained by vulcanizing the vibrationproof rubber composition has a type A durometer hardness of 50 to 70 is provided.

Claims

1. A vibrationproof rubber composition comprising: 100 parts by mass of xanthogen-modified chloroprene rubber; 0.5 to 2 parts by mass of stearic acid amide; and 4 to 5 parts by mass of erucic acid amide, wherein: the vibrationproof rubber composition further comprises carbon black with an average primary particle diameter of 60 to 470 nm, and a molded body obtained by vulcanizing the vibrationproof rubber composition has a type A durometer hardness of 50 to 70.

2. The vibrationproof rubber composition of claim 1, wherein the vibrationproof rubber composition comprises 20 to 120 parts by mass of the carbon black with an average primary particle size of 60 to 470 nm with respect to 100 parts by mass of the xanthogen-modified chloroprene rubber.

3. The vibrationproof rubber composition of claim 1, wherein the carbon black with an average primary particle size of 60 to 470 nm comprises first carbon black with an average primary particle size of 60 to 80 nm and/or second carbon black with an average primary particle size of more than 80 nm and 470 nm or less.

4. The vibrationproof rubber composition of claim 3, wherein the vibrationproof rubber composition comprises 20 to 64 parts by mass of the first carbon black and/or 50 to 120 parts by mass of the second carbon black with respect to 100 parts by mass of the xanthogen-modified chloroprene rubber.

5. A vulcanized molded body obtained by vulcanizing the vibrationproof rubber composition of claim 1.

6. A vibrationproof rubber using the vulcanized molded body of claim 5.

Description

EXAMPLES

[0058] The invention will be described in more detail based on the Examples below, but the invention is not to be construed as limited to these Examples.

<Examples 1 to 8 and Comparative Examples 1 to 15>

[0059] The raw materials were mixed in the formulas shown in Tables 1 and 2 and further kneaded using two 8-inch open rolls to prepare sheets of rubber compositions with a thickness of 2.3 mm. The rubber compositions of Examples 1 to 8 and Comparative Examples 1 to 15 were produced. The obtained sheet was press-vulcanized under the conditions of 160° C., for 20 minutes and a pressure of 0.8 MPa to prepare a vulcanized molded body having a thickness of 2.0 mm.

[0060] The details of the raw materials for the rubber compositions are as follows Xanthogen-modified chloroprene rubber: DCR-66 (registered trademark), manufactured by Denka Company Limited

[0061] Mercaptan-modified chloroprene rubber: DCR-36 (registered trademark), manufactured by Denka Company Limited

[0062] Carbon black A: primary particle size 62 nm: manufactured by TOKAI CARBON CO., LTD., Seast SVH (registered trademark)

[0063] Carbon black B: primary particle size 450 nm: manufactured by Cancarb Limited, Thermax N-990 (registered trademark)

[0064] Carbon Black C: primary particle size 26 nm: manufactured by Asahi Carbon Co., Ltd., Asahi #70

[0065] Carbon black D: primary particle size 45 nm: manufactured by Asahi Carbon Co., Ltd., Asahi #60U

[0066] The other raw materials were commercially available products, respectively.

[0067] The primary particle diameter of carbon black was determined by measuring the circle equivalent diameters of 200 particles on a micrograph taken with an electron microscope in accordance with JIS Z8901 and calculating the arithmetic average value of them.

<Evaluation Method>

[0068] The physical properties of the obtained vulcanized molded body were evaluated. The evaluation method is as shown below.

(1) Tensile Strength and Elongation at Break

[0069] The tensile strength and elongation at break were measured in accordance with JIS K6251. A dumbbell-shaped No. 3 test piece was cut from a sheet of the vulcanized molded body and measurement was performed using a fully automatic rubber tensile tester (AGS H, manufactured by SHIMADZU CORPORATION) at 23° C. with a tensile speed of 500 mm/min.

(2) Type A Durometer Hardness

[0070] In accordance with JIS K6253-3, the type A durometer hardness was measured at 23° C. with three sheets of the vulcanized molded body stacked on top of each other. The hardness tester used was Asker Rubber Hardness Tester Type A, manufactured by KOBUNSHI KEIKI CO.,LTD..

(3) Vibrationproof property (Dynamic magnification)

[0071] The dynamic magnification can be calculated by measuring the dynamic spring constant (Kd) and static spring constant (Ks) under 23° C. conditions using cylindrical test pieces in accordance with the general test conditions specified in JIS K 6386. A dynamic characteristic tester (KCH701-20, manufactured by SAGINOMIYA SEISAKUSHO, INC.) was used as the measuring device.

(4) Friction Coefficient

[0072] The friction coefficient was measured using a testing machine manufactured by Bruker Corporation. As the rubber material for measuring the friction coefficient, a rubber sheet having a thickness of 2 mm was used. While pressing a friction element of the tip R6 (tip with a radius of 6 mm) against the rubber sheet with a load of 20 N, the rubber sheet was vibrated at ±25 mm in the direction perpendicular to the friction element to measure the friction coefficient at a predetermined frequency and temperature.

[Table 1]

[0073]

TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5 6 7 8 1 2 3 4 composition xantogen-modified 100 100 100 100 100 100 100 100 100 100 100 chloroprene rubber mercaptan-modified 100 chloroprene rubber carbon black a (primary particle 20 50 64 24 diameter: 62 nm) carbon black b (primary particle 100 100 100 100 50 100 35 125 100 diameter: 450 nm) carbon black c (primary particle diameter 26 nm) carbon black d (primary particle diameter: 45 nm) stearic acid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 stearic acid amide 0.5 1 2 1 0.5 0.5 0.5 0.5 0.5 0.5 0.5 5 eric acid amide 5 5 5 4 5 5 5 5 5 5 5 ethylene bisstearate amide behenoate amide paraffin wax 4,4-bis {α, α-dimethylbenzyl) 1 1 1 1 1 1 1 1 1 1 1 1 diphenylamine MgO 4 4 4 4 4 4 4 4 4 4 4 4 dioctyl sebacate 10 10 10 10 10 10 20 10 10 10 10 10 ZnO 5 5 5 5 5 5 5 5 5 5 5 5 trimethylchiurea 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 tetramethylthium disulfide 0.4 04 0.4 0.4 0.4 0.4 04 0.4 04 0.4 0.4 0.4 N-phenyl-N′-(1,3-dimethylbutyl)- 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 05 0.5 0.5 0.5 p-phenylenediamine properties of tension strength (MPa) 15.2 148 14.8 15 3 15 9 16.8 17.2 16 2 13.7 14.8 15.5 144 vulcanized stretch growth (%) 410 392 415 378 475 528 540 430 367 682 375 367 molded body hardness (Durometer-A) 65 66 65 62 53 69 68 67 65 48 72 71 (vulcanization vibrationproof property 2.28 2.32 2.29 2.15 1 94 2.18 2.28 2.25 2.54 1.80 2.48 2.22 condition: (dynamic magnification) 160° C. friction coefficient 1 Hz 0° C. 0.4 0.7 0.7 0.8 09 0.7 06 0.5 04 1.3 0.4 1.8 20 minutes) 1 Hz 70° C. 0.5 0.7 0.6 0.8 0.8 06 0.6 0.6 0.5 1.0 0.5 0.8

TABLE-US-00002 TABLE 2 Comparative Example 5 6 7 8 9 10 11 12 13 14 15 composition xantogen-modified 100 100 100 100 100 100 100 100 100 100 100 chloroprene rubber mercaptan-modified chloroprene rubber carbon black a (primary particle diameter: 62 nm) carbon black b (primary 100 100 100 100 100 100 100 100 100 particle diameter: 450 nm) carbon black c (primary 20 particle diameter: 26 nm) carbon black d (primary 24 particle diameter: 45 nm) stearic acid 0.5 0.5 0.5 5.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 stearic acid amide 2 1 0.5 0.5 eric acid amide 5 3 10 5 5 5 5 ethylene bisstearate amide 5 5 behenoate amide 5 5 paraffin wax 5 4,4′-bis (α, α-dimetbylbenzyl) 1 1 1 1 1 1 1 1 1 1 1 diphenylamine MgO 4 4 4 4 4 4 4 4 4 4 4 dioctyl sebacate 10 10 10 10 10 10 10 10 10 10 10 ZnO 5 5 5 5 5 5 5 5 5 5 5 trimethylchiurea 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 tetramethylthium disulfide 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 N-phenyl-N′-(1,3-dimethylbutyl)- 0.5 0.5 0.5 0.5 0.5 0 5 05 0.5 0.5 0.5 0.5 p-phenylenediamine properties of tension strength (MPa) 15.0 15.0 12.7 14.9 14.1 12 8 14.1 14.1 14 6 16.5 16 3 vulcanized stretch growth (%) 383 366 406 327 420 427 332 361 354 526 532 molded body hardness (Durometer-A) 66 63 63 70 65 66 70 70 67 57 55 (vulcanization vibrationproof property 2.24 2.10 3.04 2.18 2.38 2.49 1.88 2.17 2.18 2.04 2.01 condition: (dynamic magnification) 160° C. friction coefficient 1 Hz 0° C. 0.6 1.6 0.4 1.6 0.6 0.6 1.3 1.2 1.2 1.2 1.2 20 minutes) 1 Hz 70° C. 1.0 1.1 0.6 1.3 1.0 0.7 1.0 1.1 0.9 1.1 1.0