JP2015021097A - Rubber composition for vibration-proof rubber, and vibration-proof rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dynamic magnification without impairing heat resistance.SOLUTION: The rubber composition for vibration-proof rubber contains 10-100 pts.mass of carbon black based on 100 pts.mass of a diene-based rubber component including natural rubber, and 0.3-5 pts.mass of a compound represented by formula (1) based on 100 pts.mass of carbon black. In the formula, Rrepresents a hydrogen atom, a 1-6C alkyl group or alkenyl group, or a 3-6C cyclic alkyl group or alkenyl group; A represents NH, NR, O, or S; Rrepresents a 1-6C alkyl group or alkenyl group, or a 3-6C cyclic alkyl group or alkenyl group; n represents an integer of 1-6; and x represents an integer of 1-4.

Description

  The present invention relates to a rubber composition for vibration-proof rubber and vibration-proof rubber, and more specifically, vibration-proof rubber that can be suitably used for vibration-proof devices such as automobile engine mounts, strut mounts, body mounts, and suspension bushes. The present invention relates to a rubber composition for vibration and a vibration-proof rubber using the same.

  Anti-vibration rubber is used for vehicles such as automobiles in order to absorb vibrations of the engine and the vehicle body and improve riding comfort and prevent noise. As the anti-vibration rubber, a rubber composition in which carbon black as a reinforcing filler is blended with natural rubber is generally used. In such a rubber composition for vibration-proof rubber, it is required to reduce the dynamic magnification without impairing heat resistance.

  In Patent Document 1, a master batch formed by mixing a carbon black-containing slurry solution and a natural rubber latex in a liquid phase and drying is used as a rubber composition for vibration-proof rubber in order to achieve both reduction in dynamic magnification and improvement in durability. It is disclosed to use. However, it is insufficient as a technique for improving the dynamic magnification, and further improvement is required.

  Incidentally, in order to improve the dispersibility of carbon black in the rubber composition and strengthen the chemical bond between the carbon black and the rubber molecule, Patent Document 2 discloses 2,2′-bis (benzimidazolyl-2). ) A rubber-carbon black coupling agent comprising a sulfide compound such as ethyl disulfide is disclosed. However, this document is intended to demonstrate excellent wet grip performance and low fuel consumption performance as a rubber composition for tires, and discloses the application to vibration-proof rubber as well as the effect of reducing dynamic magnification. It has not been.

  Moreover, as a technique for improving the dispersibility of a filler such as carbon black, Patent Document 3 discloses that a rubber composition is obtained using a rubber wet masterbatch. However, this document improves the heat buildup, durability, and rubber strength of the pneumatic tire by improving the dispersibility of the filler, and does not disclose a reduction in the dynamic magnification of the vibration-proof rubber. .

JP 2011-132350 A JP 2013-023610 A JP 2012-144680 A

  An object of the present invention is to provide a rubber composition for vibration-proof rubber and a vibration-proof rubber capable of reducing the dynamic magnification without impairing heat resistance.

The rubber composition for vibration-proof rubber according to the present invention contains 10 to 100 parts by mass of carbon black with respect to 100 parts by mass of the diene rubber component including natural rubber, and is represented by the following general formula (1). The compound contains 0.3 to 5 parts by mass with respect to 100 parts by mass of carbon black.

In the formula, R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms, and A represents NH, NR ² , O or S, and R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. n shows the integer of 1-6, x shows the integer of 1-4.

  The anti-vibration rubber according to the present invention is obtained by vulcanization molding using the rubber composition for anti-vibration rubber.

  According to the present invention, the rubber composition for vibration-proof rubber containing the diene rubber component containing natural rubber and the carbon black is blended with the sulfide compound represented by the general formula (1), so that the heat resistance is equivalent. The dynamic magnification can be reduced while maintaining the level.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The rubber composition for vibration-proof rubber according to this embodiment is obtained by blending carbon black and a compound represented by the above general formula (1) into a diene rubber component containing natural rubber. In the compound represented by the formula (1), the sulfide bond part reacts with the rubber molecule of the diene rubber component, and the effect is that the aromatic condensed heterocyclic ring at the terminal interacts with the benzene ring on the carbon black surface. The bond between the diene rubber component and carbon black can be strengthened. As a result, the dispersibility of carbon black can be enhanced, and the reinforcing effect can be enhanced. Therefore, it is considered that the static spring constant can be increased and the dynamic magnification can be reduced. In this compound, an alkylene group is inserted between the aromatic condensed heterocyclic ring and the sulfide bond. If a heterocycle and sulfur are directly bonded, even if they are bonded to a rubber molecule, cleavage is likely to occur at the same time, and the degree of bonding decreases. However, in the above compound, an alkylene group is inserted between the heterocycle and sulfur. Therefore, it is considered that the cleavage of the bond with the rubber molecule is suppressed, so that the heat resistance can be prevented from being lowered.

  As the diene rubber component, natural rubber (NR) alone may be used, or natural rubber and diene synthetic rubber may be used in combination. Examples of the diene-based synthetic rubber include isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber (CR). One or two or more of these can be blended with natural rubber. BR and / or SBR are preferred. In addition, as these natural rubber and diene synthetic rubber, those in which a terminal or a part of the main chain is modified can be used.

  The content of the natural rubber in the diene rubber component is not particularly limited, but in order to effectively exhibit the fatigue resistance performance of the natural rubber, it may be 50 parts by mass or more with respect to 100 parts by mass of the diene rubber component. Preferably, it is 70 parts by mass or more.

Examples of the carbon black include SAF class (ASTM number N100 series), ISAF class (N200 series), HAF class (N300 series), FEF class (N500 series), GPF class (N600 series), SRF class (N700). For example). Among these, considering the low dynamic magnification, those having a CTAB adsorption specific surface area (measured in accordance with JIS K6217-3) in the range of 30 to 100 m ² / g are preferably used.

  The blending amount of the carbon black is preferably 10 to 100 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the diene rubber component, from the viewpoint of the hardness of the rubber after vulcanization, the reinforcing property and the rubber mixing property. Is 20-80 parts by mass. In the rubber composition of the present embodiment, the reinforcing filler is mainly composed of carbon black, and may be carbon black alone. However, other inorganic fillers such as silica may be used as long as the effect is not impaired. An agent may be contained.

  In the rubber composition according to this embodiment, a compound represented by the above general formula (1) is blended. This compound is a sulfide compound having a structure (bis structure) in which an aromatic condensed heterocycle is bonded to both ends of a sulfide group via an alkylene group.

In the above formula (1), R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, and an n-hexyl group. Are those having 1 to 4 carbon atoms. As an alkenyl group, a vinyl group, an allyl group, etc. are mentioned, for example, Preferably it is a C1-C4 thing. Examples of the cyclic alkyl group or alkenyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like, and an alkyl group bonded to a ring carbon atom such as a 2-methylcyclopropyl group. It may have a substituent, and further may be a group formed by removing a hydrogen atom from a side chain, such as a cyclopropylmethyl group.

A in the formula (1) represents NH, NR ² , O or S. In the case of NH or NR ² , the heterocyclic ring is a benzimidazolyl group, and in the case of O, the heterocyclic ring is a benzoxazolyl group. In the case of S, the heterocyclic ring is a benzthiazolyl group. R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms. Specific examples and preferred carbon numbers thereof are those described above for R Same as ¹ .

  N in Formula (1) shows the integer of 1-6, More preferably, it is an integer of 1-3. Moreover, x is an integer of 1-4, More preferably, it is an integer of 2-4.

  Specific examples of the compound represented by the formula (1) include bis (benzimidazolyl-2) methyl sulfide, 2,2′-bis (benzimidazolyl-2) ethyl sulfide, 2,2′-bis (benzimidazolyl- 2) Ethyl disulfide, 2,2′-bis (benzimidazolyl-2) ethyl trisulfide, 2,2′-bis (benzimidazolyl-2) ethyl tetrasulfide, 3,3′-bis (benzimidazolyl-2) propyl Disulfide, 4,4′-bis (benzimidazolyl-2) butyl disulfide, 5,5′-bis (benzimidazolyl-2) pentyl disulfide, 6,6′-bis (benzimidazolyl-2) hexyl disulfide, 2,2 '-Bis (1-methylbenzimidazolyl-2) ethyl disulfide, 2,2'-bis ( Nsoxazolyl-2) ethyl disulfide, 2,2′-bis (benzoxazolyl-2) ethyl tetrasulfide, 2,2′-bis (4-methylbenzoxazolyl-2) ethyl disulfide, 2,2′- Examples thereof include bis (benzthiazolyl-2) ethyl disulfide and 2,2′-bis (benzthiazolyl-2) ethyl tetrasulfide, and these can be used alone or in combination.

  The compound represented by formula (1) is, for example, a 1,2-diaminobenzene compound, a 2-aminothiophenol compound, or a 2-aminophenol compound, and a thiodicarboxylic acid compound of 4N. It can be synthesized by reacting in hydrochloric acid.

  Examples of the 1,2-diaminobenzene compounds include 1,2-diaminobenzene, 2,3-tolylenediamine, 1,2-diamino-3-ethylbenzene, 1,2-diamino-3-n-propylbenzene. 1,2-diamino-3-isopropylbenzene, 1,2-diamino-3-n-butylbenzene and the like. Examples of the 2-aminothiophenol compound include 2-aminothiophenol, 2-amino-3-methylthiophenol, 2-amino-3-ethylthiophenol, 2-amino-3-n-propylthiophenol, 2 -Amino-4-methylthiophenol, 2-amino-4-ethylthiophenol, 2-amino-4-n-propylthiophenol, 2-amino-5-methylthiophenol, 2-amino-5-ethylthiophenol, 2 -Amino-5-n-propylthiophenol, 2-amino-6-methylthiophenol, 2-amino-6-ethylthiophenol, 2-amino-6-n-propylthiophenol and the like. Examples of 2-aminophenol compounds include 2-aminophenol, 2-amino-3-methylphenol, 2-amino-3-ethylphenol, 2-amino-3-n-propylphenol, and 2-amino-4. -Methylphenol, 2-amino-4-ethylphenol, 2-amino-4-n-propylphenol, 2-amino-5-methylphenol, 2-amino-5-ethylphenol, 2-amino-5-n- Examples include propylphenol, 2-amino-6-methylphenol, 2-amino-6-ethylphenol, and 2-amino-6-n-propylphenol. Examples of the thiodicarboxylic acid compound include thiodiglycolic acid, dithiodiglycolic acid, tetrathiodiglycolic acid, thiodipropionic acid, dithiodipropionic acid, trithiodipropionic acid, tetrathiodipropionic acid, dithiodibutyric acid. Tetrathiodibutyric acid, dithiodipentylic acid, tetrathiodipentylic acid, dithiodihexylic acid, tetrathiodihexylic acid and the like.

  It is preferable that the compounding quantity of the compound represented by Formula (1) is 0.3-5 mass parts with respect to 100 mass parts of carbon black. By setting it as such a compounding quantity, a static spring constant can be raised and dynamic magnification can be reduced. The compounding amount of the compound is more preferably 1.0 to 3.0 parts by mass.

  In the rubber composition according to this embodiment, as the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea, which are usually used for rubber vulcanization, are used. Vulcanization accelerators such as vulcanization accelerators, guanidine vulcanization accelerators, and dithiocarbamate vulcanization accelerators can be used alone or in appropriate combination. As a compounding quantity of a vulcanization accelerator, it is preferable that it is 0.1-5 mass parts with respect to 100 mass parts of diene rubber components, More preferably, it is 0.5-3.0 mass parts.

  In this embodiment, it is preferable to mix a thiuram vulcanization accelerator among the above. The thiuram vulcanization accelerator is generally added to increase the vulcanization speed. According to this embodiment, the combined use with the compound represented by the above formula (1) maintains the dynamic ratio, An unexpected effect that the static spring constant can be increased is obtained. Therefore, when comparing with the same static spring constant, the dynamic magnification can be reduced by the increase of the static spring constant, and the vibration isolation performance can be further improved, such as excellent noise blocking effect in a high frequency range. .

  Examples of the thiuram vulcanization accelerator include tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), and tetrakis (2-ethylhexyl) thiuram. Examples thereof include disulfide, dipentamethylene thiuram tetrasulfide (DPTT), dipentamethylene thiuram hexasulfide and the like, and these can be used alone or in combination of two or more. The compounding amount of the thiuram vulcanization accelerator is preferably 0.05 to 1.0 part by mass, more preferably 0.1 to 0.5 part by mass with respect to 100 parts by mass of the diene rubber component. .

  Further, other vulcanization accelerators may be used in combination with the thiuram vulcanization accelerator, and the sulfenamide vulcanization accelerator is preferred as the vulcanization accelerator used in combination. Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N, N -Dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), N-oxydiethylene-2-benzothiazolylsulfenamide (OBS), N, N-diisopropyl-2-benzothiazolylsulfenamide (DPBS), N, N-di (2-ethylhexyl) -2-benzothiazolylsulfenamide, N, N-di (2-methylhexyl) -2-benzothiazolylsulfenamide and the like can be mentioned. Species or a combination of two or more can be used. As a compounding quantity of the vulcanization accelerator used together, it is preferable that it is 0.1-3 mass parts with respect to 100 mass parts of diene rubber components, More preferably, it is 0.5-1.5 mass parts.

  In addition to the above components, the rubber composition according to the present embodiment may contain various additives such as zinc white, stearic acid, anti-aging agent, softener, wax, vulcanizing agent, and vulcanization retarder. it can. Examples of the vulcanizing agent include sulfur components such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. Although not particularly limited, the blending amount thereof is 100 masses of the diene rubber component. It is preferable that it is 0.2-7 mass parts with respect to a part, More preferably, it is 0.5-5 mass parts, Furthermore, it is 1-4 mass parts.

  The rubber composition according to the present embodiment can be prepared by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer. For example, in the first mixing stage, carbon black and other additives except for the vulcanizing agent and the vulcanization accelerator are added to and mixed with the diene rubber, and then added to the resulting mixture in the final mixing stage. The rubber composition can be prepared by adding and mixing the compound represented by the formula (1) together with the vulcanizing agent and the vulcanization accelerator. The compound represented by the formula (1) may be added and mixed in the first mixing stage.

  In a preferred embodiment, a rubber wet masterbatch containing natural rubber and carbon black is used. That is, the natural rubber and carbon black are preferably blended using a master batch obtained by mixing natural rubber latex and a carbon black-containing slurry solution in a liquid phase and drying. By combining the masterbatch with the coupling agent represented by the above formula (1) in a state in which the dispersibility of carbon black with respect to natural rubber is improved in advance by forming a masterbatch in this way, a coupling agent is obtained. It is possible to strengthen the bond between natural rubber and carbon black, and to improve the dynamic magnification improvement effect. In this case, the compound represented by the formula (1) is preferably added and mixed in the final mixing stage, but may be added and mixed in the first mixing stage together with the rubber wet masterbatch.

  The method for forming the master batch is not particularly limited, and a method described in JP 2012-144680 A or JP 2011-132350 A may be employed. For example, the carbon black-containing slurry solution can be produced by mixing carbon black and a dispersion solvent such as water using a general dispersing machine such as a high shear mixer or a homomixer. Although the carbon black density | concentration in a carbon black containing slurry solution is not specifically limited, It is preferable that it is 1-20 mass%, More preferably, it is 3-10 mass%. The natural rubber latex is preferably a natural rubber / water system in which the dispersion solvent is water. The solid content (rubber) concentration of the natural rubber latex is preferably 10 to 60% by mass, more preferably 20 to 30% by mass. In order to mix the carbon black-containing slurry solution and the natural rubber latex in a liquid phase, a general dispersing machine such as a high shear mixer or a homomixer can be used. As a drying method after mixing, a coagulant such as formic acid may be added and dried after coagulation, or may be dried without coagulation.

  In the rubber composition according to the present embodiment, when such a master batch is used, the natural rubber and carbon black may be composed only of those derived from the master batch, and may be mixed with other components (for example, In the first mixing step), natural rubber and / or carbon black may be additionally mixed.

  The rubber composition according to the present embodiment is a dynamic magnification which is a ratio (Kd / Ks) of a 100 Hz dynamic spring constant (Kd) to a static spring constant (Ks) measured for a vulcanized product at 150 ° C. for 25 minutes. Is preferably 5.0 or less. In general, the dynamic magnification can be reduced by using carbon black having a larger particle diameter or reducing the amount of carbon black. And especially in the said rubber composition, a dynamic magnification can be further lowered | hung by mix | blending the compound represented by the said Formula (1) with natural rubber and carbon black. The dynamic magnification is more preferably 2.0 or less, and still more preferably 1.5 or less. The lower the dynamic magnification, the better from the viewpoint of vibration proof performance, so the lower limit is not particularly limited, but is usually 1.0 or more.

  The rubber composition according to the present embodiment can obtain an anti-vibration rubber by performing vulcanization after molding into a predetermined shape. That is, the rubber composition according to the embodiment can be obtained by molding the rubber composition into a shape corresponding to the rubber member in the vibration isolator by injection molding or the like and performing heat treatment. Although it does not specifically limit as vulcanization temperature, It can be set as 120-200 degreeC, More preferably, it is 140-180 degreeC.

  As described above, the obtained vibration-proof rubber has a dynamic magnification of 5.0 or less, more preferably 2.0 or less, still more preferably 1.5 or less, and the dynamic magnification can be lowered. In general, the static spring constant and the dynamic magnification have a proportional relationship that the larger the static spring constant is, the larger the dynamic magnification is. On the other hand, according to the present embodiment, it is possible to reduce the dynamic magnification while breaking the proportional relationship and increasing the static spring constant, and the vibration isolation performance can be further improved.

  Specific examples of the anti-vibration rubber according to this embodiment include engine mounts, strut mounts, body mounts, cab mounts, member mounts, differential mounts and other mounts, suspension bushings, arm bushings, torque bushing bushes, and torsional dampers. And various types of anti-vibration rubber for automobiles such as muffler hangers, damper pulleys, and dynamic dampers. In addition to automobiles, it can be suitably used for anti-vibration rubber for railway vehicles, anti-vibration rubber for industrial machinery, seismic isolation rubber for construction, seismic isolation rubber bearings, etc., and seismic isolation rubber.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. The raw materials used in the examples and comparative examples are as follows.

[raw materials]
NR (1): natural rubber, RSS # 3
・ Natural rubber latex: “HA-NR” manufactured by Resitex, DRC (Dry Rubber Content) = 60% by mass
-NR (2): natural rubber latex coagulated and dried-BR: butadiene rubber, "Buna CB22" manufactured by LANXESS
-SBR: Styrene butadiene rubber, "Nipol NS116" manufactured by Nippon Zeon Co., Ltd.
Carbon black GPF: “Seast V” manufactured by Tokai Carbon Co., Ltd. (CTAB = 37 m ² / g)
Carbon black FEF: “Seast SO” manufactured by Tokai Carbon Co., Ltd. (CTAB = 49 m ² / g)
Carbon black T-NS: “Show Black N330T” manufactured by Cabot Japan Co., Ltd. (CTAB = 80 m ² / g)
・ Oil: “Process NC140” manufactured by JOMO
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Zinc flower: "Zinc flower No. 1" manufactured by Mitsui Mining & Smelting Co., Ltd.
-Wax: “OZOACE 2701” manufactured by Nippon Seiki Co., Ltd.
Anti-aging agent 6PPD: “SANTOFLEX 6PPD” manufactured by Flexsys
Anti-aging agent RD: “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Sulfur: "Sulfur powder for rubber 150 mesh" manufactured by Hosoi Chemical Co., Ltd.
・ Vulcanization accelerator TS: Tetramethylthiuram monosulfide, “Noxeller TS” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator TT: Tetramethylthiuram disulfide, “Noxeller TT-P” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide, “Noxeller CZ-G (CZ)” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Vulcanization retarder: “Retarder CTP” manufactured by Ouchi Shinsei Chemical Co., Ltd.
2EBZ: 2,2′-bis (benzimidazolyl-2) ethyl disulfide (Reference Example 1 in paragraph 0033 in JP2013-23610)
4EBZ: 2,2′-bis (benzimidazolyl-2) ethyl tetrasulfide (Reference Example 2 in paragraph 0034 in JP2013-23610)

  Each evaluation method is as follows.

[Tensile properties]
Tensile strength and elongation at break were measured for a vulcanized rubber sample (vulcanization condition: 150 ° C. × 25 minutes) produced using a JIS No. 3 dumbbell based on JIS K6251. Table 1 is Comparative Example 1-1, Table 2 is Comparative Example 2-1, Table 3 is Comparative Example 3-1, Table 4 is Comparative Example 4-1, Table 5 is Comparative Example 5-1, and Table 6 is Comparative Example. In Table 6-1, Table 7 shows the value of Comparative Example 7-1 as an index of 100. The larger the index, the greater the tensile strength and elongation at break, indicating superior tensile properties.

[Dynamic magnification]
For a vulcanized rubber sample (50 mmΦ × 25 mm) obtained by vulcanizing each rubber composition at 150 ° C. × 25 minutes using a predetermined mold, the static spring constant Ks and the dynamic spring constant Kd are calculated as follows. And the ratio (Kd / Ks) was calculated to determine the dynamic magnification.

・ Static spring constant (Ks): Tensilon manufactured by Orientec Co., Ltd. was used as a measuring machine, and vulcanized rubber samples were compressed between 0 and 5 mm (compression up to 20%) at a crosshead speed of 10 mm / min. Repeatedly, a second load-deflection diagram was drawn and calculated based on the following equation.

Static spring constant (N / mm) = (w2-w1) / (δ2-δ1)
(W1 is a load (N) when the deflection amount δ1 is 1.3 mm, and w2 is a load (N) when the deflection amount δ2 is 3.8 mm.)
-Dynamic spring constant (Kd): Using a dynamic servo manufactured by Kashiwamiya Seisakusho Co., Ltd. as a measuring machine, performing initial strain (compression) 10%, frequency 100 Hz, amplitude ± 0.05 mm (± 0.2%), JIS K6394 (The unit is N / mm).

[Heat resistance: heat aging performance]
Separately prepare a vulcanized rubber sample whose tensile properties were measured, and use a “Gear Oven” manufactured by Toyo Seiki Co., Ltd. to heat-age at a temperature of 100 ° C. for 72 hours. It was measured. The ratio of the value after thermal aging to the value of tensile strength and elongation at break of the vulcanized rubber sample that was not heat-aged in each case was defined as the retention ratio of tensile strength and elongation at break. -1, Table 2 Comparative Example 2-1, Table 3 Comparative Example 3-1, Table 4 Comparative Example 4-1, Table 5 Comparative Example 5-1, Table 6 Comparative Example 6-1 and Table 7 Then, the value of the retention rate in Comparative Example 7-1 was displayed as an index with each value being 100. Both the tensile strength and elongation at break indicate that the larger the index, the higher the retention after heat aging and the better the heat resistance.

[First embodiment]
Using a Banbury mixer, in accordance with the composition (parts by mass) shown in Table 1 below, first, in the first mixing stage, components other than sulfur, vulcanization accelerator, and 2EBZ and 4EBZ are added and mixed (the discharge temperature during mixing is 160 ° C.) Then, sulfur, a vulcanization accelerator, and 2EBZ or 4EBZ were added to and mixed with the obtained mixture in the final mixing stage to prepare a rubber composition for vibration-proof rubber. About each rubber composition, the vulcanized rubber was produced and the characteristic was evaluated.

  The results are as shown in Table 1, and in comparison with Comparative Examples 1-1 to 1-3, Examples 1-1 to 1-5 blended with 2EBZ or 4EBZ, while maintaining heat resistance, a static spring The dynamic magnification was reduced while increasing the constant, and the anti-vibration performance was even better. In addition, as shown in Examples 1-2, 1-3, 1-5, by adding a thiuram vulcanization accelerator, the dynamic magnification is higher than that of Examples 1-1, 1-4 not blended. While maintaining, the static spring constant was high, and the anti-vibration performance was even better.

[Second to fifth embodiments]
According to the formulation (parts by mass) shown in Tables 2 to 5 below, rubber compositions for vibration-proof rubber were prepared in the same manner as in the first example, and vulcanized rubbers were prepared for the respective rubber compositions and the characteristics were evaluated. . The results are shown in Tables 2-5.

  As shown in Tables 2 and 3, even in the case of a blend of natural rubber and butadiene rubber or styrene butadiene rubber, it was found that Examples 2-1 to 2-4 and 3-1 were blended with 2EBZ or 4EBZ. Compared to Comparative Example 2-1 or Comparative Example 3-1, which is Toll, the dynamic magnification was reduced while increasing the static spring constant while maintaining heat resistance, and the vibration-proof performance was remarkably improved.

  In addition, as shown in Tables 4 and 5, even when the type of carbon black is changed to one having a smaller particle size, Examples 4-1 to 4-3 and 5-1 are blended with 2EBZ or 4EBZ. Compared to Comparative Example 4-1 or Comparative Example 5-1, which is a control, the dynamic magnification is reduced while maintaining the heat resistance and increasing the static spring constant, and the vibration-proof performance is remarkably improved. It was.

[Sixth and seventh embodiments]
According to the composition (parts by mass) shown in Table 6 and Table 7 below, rubber compositions for vibration-proof rubber were prepared in the same manner as in the first example, and vulcanized rubbers were prepared for each rubber composition and evaluated for characteristics. did. The production methods of master batches A and B in Tables 6 and 7 are as follows.

Master batch A: using natural rubber latex and carbon black FEF, in accordance with Example 1 of JP 2012-144680 A, the composition of the master batch is 45.2 parts by mass of carbon black with respect to 100 parts by mass of rubber. It was manufactured to become.

Masterbatch B: Using natural rubber latex and carbon black FEF, in accordance with Example 1 of JP2012-144680A, the composition of the masterbatch is 53.0 parts by mass of carbon black with respect to 100 parts by mass of rubber. It was manufactured to become.

  The results are as shown in Tables 6 and 7. When Comparative Examples 6-1 and 6-2 were compared, the dynamic spring rate was reduced by using the master batch, but the static spring constant was also lowered. This is considered to be due to the fact that the aggregated portion of carbon black is reduced and the hardness due to the aggregated portion is reduced by making the master batch. In contrast, in Examples 6-1 and 6-2, the dynamic magnification was reduced while increasing the static spring constant as compared with Comparative Example 6-1. In addition, when Examples 6-1 and 6-2 were compared, the use of the master batch reduced the dynamic magnification without lowering the static spring constant, and a more excellent effect was obtained. This is because, in the case of the example, since the dispersibility is good without blending the compound of the formula (1), there is no decrease in hardness due to the aggregated portion of the carbon black as in the comparative example. This is probably because of this. As shown in Table 7, when the thiuram vulcanization accelerator was blended, the same remarkable improvement effect as in Table 6 was obtained.

Claims (5)

While containing 10 to 100 parts by mass of carbon black with respect to 100 parts by mass of the diene rubber component including natural rubber, the compound represented by the following general formula (1) is 0.3% with respect to 100 parts by mass of carbon black. A rubber composition for an anti-vibration rubber, comprising ˜5 parts by mass.

(In the formula, R ¹ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms, and A represents NH, NR ² , O or S, and R ² represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms, or a cyclic alkyl group or alkenyl group having 3 to 6 carbon atoms, where n is (An integer of 1-6 is shown, and x is an integer of 1-4.)   The rubber composition for vibration-proof rubber according to claim 1, wherein the thiuram vulcanization accelerator is contained in an amount of 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the diene rubber component.   The said natural rubber and the said carbon black were mix | blended using the masterbatch formed by mixing a natural rubber latex and a carbon black containing slurry solution in a liquid phase, and drying. Rubber composition for anti-vibration rubber.   A dynamic magnification which is a ratio (Kd / Ks) of a dynamic spring constant (Kd) at 100 Hz to a static spring constant (Ks) measured for a vulcanized product vulcanized at 150 ° C. for 25 minutes is 5.0 or less. The rubber composition for vibration-proof rubber according to any one of claims 1 to 3.   A vibration-proof rubber obtained by vulcanization molding using the rubber composition for vibration-proof rubber according to any one of claims 1 to 4.