JP6475008B2 - Anti-vibration rubber - Google Patents

Description

  The present invention relates to an anti-vibration rubber, and more particularly to an anti-vibration rubber that constitutes an anti-vibration device such as an engine mount, strut mount, body mount, and suspension bush of an automobile.

  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. Such anti-vibration rubber is required to achieve both a reduction in dynamic magnification (dynamic spring constant / static spring constant) and improvement in durability at a high level.

  In Patent Document 1, in order to achieve such an object, in a rubber composition for vibration-proof rubber, natural rubber latex and a slurry containing carbon black are mixed in a liquid phase and dried while optimizing the particle size of carbon black. It is disclosed that a rubber wet masterbatch is used. However, in this document, carbon black having a large particle size is used to reduce the dynamic magnification, and it cannot be said that this technique is suitable for carbon black having a small particle size.

  On the other hand, Patent Document 2 discloses that the dynamic magnification of a vibration-proof rubber is reduced by blending a thiosulfuric acid compound such as S- (3-aminopropyl) thiosulfuric acid or a salt thereof. However, it does not disclose use in combination with a rubber wet masterbatch, and does not mention the effect of improving durability.

  As a technique related to a rubber wet masterbatch, Patent Document 3 discloses carbon black to which natural rubber latex particles are adhered by adding at least a part of natural rubber latex when carbon black is dispersed in a dispersion solvent. It is disclosed that after the slurry containing it is mixed, the slurry and the remaining natural rubber latex are mixed, coagulated, and dried, but there is no mention of the effect of reducing dynamic magnification and improving durability. .

JP 2011-132350 A JP 2013-049838 A Japanese Patent No. 4738551

  An object of the present invention is to provide a vibration-proof rubber capable of achieving both reduction in dynamic magnification and improvement in durability.

  The anti-vibration rubber according to the present invention is a rubber wet masterbatch containing 5 to 100 parts by mass of carbon black with respect to 100 parts by mass of natural rubber obtained by mixing natural rubber latex and carbon black-containing slurry in a liquid phase and drying. And a thiosulfuric acid compound represented by the following formula (1) and / or a salt thereof, and the thiosulfuric acid compound and / or the salt thereof is 0.05 to 5 with respect to 100 parts by mass of the rubber component. A rubber composition containing parts by mass is formed by vulcanization molding.

式（１）において、ｎは０〜１０の整数を示す。

In the formula (1), n represents an integer of 0 to 10.

  According to the present invention, by using a rubber wet masterbatch and a thiosulfuric acid compound in combination, a reduction in dynamic magnification and an improvement in durability can be achieved at a high level.

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

  The anti-vibration rubber according to the present embodiment is a rubber composition comprising a rubber wet masterbatch containing natural rubber and carbon black, and a thiosulfuric acid compound represented by formula (1) and / or a salt thereof. Is formed by vulcanization molding. Even if rubber wet masterbatch and thiosulfuric acid compound are each applied alone, the effects of reducing dynamic magnification and improving durability can be obtained. It was found that an excellent coexistence effect of reducing dynamic magnification and improving durability can be obtained. The reason for this is not clear, but it is considered that the thiosulfuric acid compound acts on the carbon black dispersed in the rubber wet masterbatch to bring out more performance than when it is used alone.

  As the rubber wet masterbatch, a slurry in which carbon black is dispersed in a dispersion solvent (that is, a carbon black-containing slurry) and natural rubber latex are mixed in a liquid phase and dried, and used. What was produced by the well-known method may be used and a commercial item may be used. As one embodiment, when the method described in Japanese Patent No. 4738551, that is, when carbon black is dispersed in a dispersion solvent, at least a part of natural rubber latex is added, whereby carbon with natural rubber latex particles attached thereto is added. After the slurry containing black is produced, the slurry and the remaining natural rubber latex may be mixed, then coagulated and dried, and the above-mentioned compatibility effect can be enhanced.

  As the natural rubber latex, concentrated latex, fresh latex called field latex, and the like can be used without distinction, and a concentration adjusted by adding water as necessary may be used. For example, natural rubber concentrated latex (DRC (Dry Rubber Content) = 60%) manufactured by Regitex, NR field latex (DRC = 31.2%) manufactured by Golden Hope, etc. are commercially available and can be used. The solid content (rubber) concentration of the natural rubber latex is not particularly limited, and may be, for example, 10 to 60% by mass or 20 to 30% by mass.

  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 series). ) Etc. are used. Among these, it is preferable to use at least one selected from the group consisting of HAF class, FEF class, and GPF class.

  As the dispersion solvent for dispersing carbon black, water is preferably used, but water containing an organic solvent may be used, for example. The carbon black concentration in the carbon black-containing slurry is not particularly limited, and may be, for example, 1 to 20% by mass or 3 to 10% by mass.

  When preparing a slurry containing carbon black to which natural rubber latex particles are adhered, the amount of natural rubber latex added is preferably 0.5 to 50% by mass based on the total amount of natural rubber latex used. . Moreover, the solid content (rubber) amount of the natural rubber latex to be added is preferably 0.5 to 10%, more preferably 1 to 6% in terms of mass ratio with respect to carbon black.

  For the preparation of these slurries and the mixing of the slurry and the latex solution, for example, a general disperser such as a high shear mixer, a high-pressure homogenizer, an ultrasonic homogenizer, or a colloid mill can be used. As the coagulant for coagulation and drying, acids such as formic acid and sulfuric acid that are usually used for coagulating natural rubber latex, and salts such as sodium chloride can be used. As a method of dehydrating and drying after coagulation, various drying apparatuses such as an oven, a vacuum dryer, and an air dryer may be used, and dehydration and drying may be performed while applying mechanical shearing force using an extruder.

  The rubber wet masterbatch preferably contains 5 to 100 parts by mass of carbon black with respect to 100 parts by mass of natural rubber. That is, the amount of carbon black contained in the rubber wet masterbatch may be 5 to 100 parts by mass, 10 to 80 parts by mass, or 15 to 70 parts by mass with respect to 100 parts by mass of natural rubber. -60 mass parts may be sufficient. In addition to natural rubber and carbon black, the rubber wet masterbatch, for example, surfactants, zinc oxide, stearic acid, anti-aging agents, softeners such as wax and oil, processing aids, etc., as desired. You may mix | blend the compounding agent normally used in the rubber industry.

  In the rubber composition of the present embodiment, the rubber component may be composed only of natural rubber derived from the rubber wet masterbatch, but may contain additional diene rubber. It is preferable that at least 10% by mass of the rubber component contained in the rubber composition is natural rubber derived from the rubber wet masterbatch. That is, the rubber component is preferably a natural rubber derived from a rubber wet masterbatch alone or a blend of 10% by mass or more of the natural rubber and 90% by mass or less of another diene rubber. The natural rubber derived from the rubber wet masterbatch may be 25% by mass or more, 50% by mass or more, or 70% by mass or more of the rubber component.

  Examples of the additional diene rubber include natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), or These modified rubbers may be mentioned, and any one or more of these may be blended. Preferably, it is at least one selected from the group consisting of NR, BR and SBR.

  In the rubber composition of the present embodiment, the carbon black may be composed of only carbon black derived from the rubber wet masterbatch, but may contain additional carbon black. At least 15% by mass of the carbon black contained in the rubber composition is preferably carbon black derived from the rubber wet masterbatch, more preferably 40% by mass or more, and further preferably 70% by mass or more. That is, in addition to carbon black contained in the rubber wet masterbatch, carbon black may be added by post-addition, but the amount of carbon black added after is 85% by mass of the total carbon black contained in the rubber composition The content is preferably 60% by mass or less, more preferably 30% by mass or less of the total amount of carbon black. The total amount of carbon black contained in the rubber composition is, for example, preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass, and still more preferably 100 parts by mass of the rubber component. Is 30-60 parts by mass.

  The rubber composition of this embodiment is blended with the thiosulfuric acid compound represented by the above formula (1) and / or a salt thereof. As described above, not only a thiosulfate compound but also a salt thereof may be used, but it is preferable to use a thiosulfate compound that is not a salt because thiosulfate has deliquescence and poor storage properties. Here, examples of the salt include alkali metal salts such as lithium salt, sodium salt, potassium salt, and cesium salt; transition metal salts such as cobalt salt and copper salt; typical metal salts such as zinc salt; ammonium salt, trimethylammonium salt and the like And substituted or unsubstituted ammonium salts. Moreover, when using a thiosulfuric acid compound and its salt as a mixture thereof, such a mixture is, for example, a method of mixing a thiosulfuric acid compound and its salt, or a method of metallizing a part of a thiosulfuric acid compound using a metal alkali. A product obtained by a method of neutralizing a part of a metal salt of a thiosulfuric acid compound using a protonic acid can be used.

  Examples of the thiosulfuric acid compound represented by the above formula (1) include S- (2-aminoethyl) thiosulfuric acid, S- (3-aminopropyl) thiosulfuric acid, S- (4-aminobutyl) thiosulfuric acid, S- (5-aminopentyl) thiosulfuric acid, S- (6-aminohexyl) thiosulfuric acid, S- (7-aminoheptyl) thiosulfuric acid, S- (8-aminooctyl) thiosulfuric acid, S- (9-aminononyl) ) Thiosulfuric acid, S- (10-aminodecyl) thiosulfuric acid, S- (11-aminoundecyl) thiosulfuric acid, S- (12-aminododecyl) thiosulfuric acid, and n in formula (1) is 0 to It is preferably an integer of 4, more preferably n is an integer of 1 to 3, and still more preferably S- (3-aminopropyl) thiosulfuric acid where n is 1.

  The thiosulfate compound can be produced by any known method such as the method described in JP2013-49838A. For example, a monohaloalkylamine hydrochloride and a metal salt or ammonium salt of thiosulfate are used. It can be made to react. A salt of a thiosulfuric acid compound may be produced by neutralizing with a protic acid such as hydrochloric acid or sulfuric acid. Examples of the salt of the thiosulfuric acid compound include a method of reacting a monohaloalkylamine with a metal salt or ammonium salt of thiosulfuric acid, a reaction of a phthalimide potassium salt with a dihaloalkane, and a metal salt of thiosulfuric acid or It can be produced by a method such as a method of reacting with an ammonium salt.

  The amount of the thiosulfuric acid compound and / or salt thereof is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the rubber component. Preferably it is 0.2-2 mass parts.

  In addition to the above components, the rubber composition according to the present embodiment includes various additives such as zinc white, stearic acid, anti-aging agent, softener, wax, vulcanizing agent, vulcanization accelerator, and vulcanization retarder. Can be blended. 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 parts by mass of the rubber component. It is preferable that it is 0.2-5 mass parts with respect to it, More preferably, it is 0.5-3 mass parts.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Vulcanization accelerators such as accelerators and dithiocarbamate vulcanization accelerators may be used alone or in admixture as appropriate. Among these, sulfenamide vulcanization accelerators are preferable from the viewpoint of the effect of reducing dynamic magnification. 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 said rubber components, More preferably, it is 0.2-3 mass parts.

  The rubber composition 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, the rubber thiosulfuric compound and / or salt thereof and other additives excluding the vulcanizing agent and the vulcanization accelerator (optional diene rubber and carbon) A rubber composition can be prepared by adding and mixing a black (which may contain black), and then adding and mixing a vulcanizing agent and a vulcanization accelerator in the final mixing stage. The temperature of the rubber composition at the end of mixing in the first mixing stage is preferably 150 ° C. or higher (for example, 150 to 180 ° C.) in order to promote the reaction of the thiosulfuric acid compound and / or its salt. In promoting the reaction, the mixing time of 150 ° C. or more may be extended.

  The anti-vibration rubber according to the present embodiment is formed by vulcanization molding using the rubber composition. For example, the rubber composition is molded by injection molding or the like into a shape corresponding to the rubber member in the anti-vibration device. Then, by performing heat treatment, the vibration-proof rubber according to the embodiment is obtained. Although it does not specifically limit as vulcanization temperature, It can be set as 120-200 degreeC, More preferably, it is 140-180 degreeC.

  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. Details of each component used in the examples and comparative examples are as follows.

・ NR: Natural rubber, RSS # 3
-BR: Butadiene rubber, "Buna CB22" manufactured by LANXESS
・ Carbon Black FEF: “Seast SO” manufactured by Tokai Carbon
・ Carbon black HAF: “Seast 3” manufactured by Tokai Carbon
・ Zinc flower: “Zinc flower No. 1” manufactured by Mitsui Mining & Mining
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Wax: “OZOACE2701” manufactured by Nippon Seisakusha
Anti-aging agent RD: “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
Anti-aging agent 6C: “SANTOFLEX 6PPD” manufactured by Flexsys
・ Sulfur: "Sulfur powder for rubber 150 mesh" manufactured by Hosoi Chemical Co., Ltd.
・ Vulcanization accelerator CZ: “Noxeller CZ-G (CZ)” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Vulcanization accelerator TS: “Suncellor TS” manufactured by Sanshin Chemical Industry Co., Ltd.
・ Vulcanization retarder CTP: “Anscorch CTP” manufactured by Kawaguchi Chemical Industry Co., Ltd.

  Thiosulfuric acid compound: S- (3-aminopropyl) thiosulfuric acid. What was synthesize | combined by the method of Paragraph 0041 of Unexamined-Japanese-Patent No. 2013-49838.

  Masterbatch 1: A rubber wet masterbatch containing 50 parts by mass of carbon black FEF with respect to 100 parts by mass of natural rubber. What was produced by the method of Paragraphs 0055-0058 of patent 4738551. Specifically, as natural rubber latex, natural rubber concentrated latex (DRC = 60%) manufactured by Regitex is used, and 50 parts by mass of carbon black FEF is added to dilute latex adjusted to 0.5% by mass (latex). The solid content (rubber amount) is 1% by mass with respect to carbon black, and carbon black is dispersed using PRIMIX Robomix to produce a carbon black-containing slurry with natural rubber latex particles attached. did. To the obtained carbon black-containing slurry, add the remaining natural rubber latex (adjusted by adding water so that the solid content concentration is 25% by mass) so that the total rubber amount becomes 100 parts by mass, Subsequently, mixing was performed using a household mixer SM-L56 type manufactured by SANYO to produce a natural rubber latex containing carbon black. To the resulting carbon black-containing natural rubber latex, a 10% by weight aqueous solution of formic acid as a coagulant is added until pH 4 is reached, and the coagulum is dried to a moisture content of 1.5% or less with a Suehiro EPM screw press V-01 type. By doing this, the master batch 1 was manufactured.

  Masterbatch 2: A rubber wet masterbatch containing 40 parts by mass of carbon black FEF with respect to 100 parts by mass of natural rubber. Carbon black FEF was added in an amount of 40 parts by mass, and the others were prepared in the same manner as Masterbatch 1.

  Master batch 3: A rubber wet master batch containing 50 parts by mass of carbon black HAF with respect to 100 parts by mass of natural rubber. Carbon black HAF was used instead of carbon black FEF, and the others were produced in the same manner as Masterbatch 1.

  The evaluation method of the rubber composition is as follows.

[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) is calculated to determine the dynamic magnification. Tables 1 and 4 show the values of Comparative Example 1, Table 2 shows the values of Comparative Example 4, and Table 3 shows the values of Comparative Example 7. , And each index was set to 100. The smaller the index, the lower the dynamic magnification and the better the dynamic characteristics.
・ 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): DYNAMIC SERVO Co., Ltd. dynamic servo is used as a measuring machine, initial strain (compression) is 10%, frequency is 100 Hz, amplitude is ± 0.05 mm (± 0.2%). JIS K6394 (The unit is N / mm).

[Fatigue endurance test]
As a test piece for the durability test, two cylindrical metal fittings having an outer diameter of 40 mm and a thickness of 5 mm were paired, and vulcanized rubber was poured and connected between them. The vulcanized rubber was 30 mm in diameter and 22 mm in thickness. Two pairs of the test pieces were set as one set, and were installed so as to be symmetric with respect to the excitation axis extending from the load cell of the testing machine. A displacement (deflection) of 0.5 mm is applied to the test piece in the direction of the excitation axis. From the load-deflection diagram at that time, the load when the deflection amount is 0.1 mm and the deflection amount are 0.1. The load at 4 mm was obtained, and the spring constant was calculated from the quotient of the difference between both loads and the difference in deflection. In Tables 1 and 4, the spring constants are shown as indices with the values of Comparative Example 1, Table 2 as Comparative Example 4, and Table 3 as Comparative Example 7 as 100, respectively.

  In addition, the test piece is subjected to constant vibration at a frequency of 3 Hz with a load of 1.2 kN, and the number of vibrations until the vulcanized rubber breaks is measured. The number of vibrations is used as an index of durability. The results are shown in the table as the endurance times. In Tables 1 and 4, the number of times of endurance was expressed as an index with the value of Comparative Example 1 being set, Table 2 being the value of Comparative Example 4 and Table 3 being the value of Comparative Example 7 being 100. The larger the index, the better the durability.

[First embodiment]
Using a Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, in the first mixing stage, components other than sulfur, vulcanization accelerator and vulcanization retarder are added and mixed (discharge temperature during mixing) Then, sulfur and a vulcanization accelerator 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. In each rubber composition, the blending amount of carbon black was adjusted so that the spring constant was substantially constant.

  The results are as shown in Table 1. In Examples 1 to 3 in which a rubber wet masterbatch and a thiosulfate compound were used in combination with Comparative Example 1 as a control, the durability was remarkably improved and the dynamic magnification was also increased. It was greatly reduced. Both the durability and the dynamic ratio are more improved than the improvements of Comparative Example 2 and Comparative Example 3 in which the rubber wet masterbatch and the thiosulfuric acid compound were used alone, respectively. About durability, the synergistic effect more than the sum of the improvement allowance (+120) of the comparative example 2 and the improvement allowance (+13) of the comparative example 3 was acquired (+223 in Example 1).

[Examples 2 to 4]
According to the composition (parts by mass) shown in Tables 2 to 4 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 2-4.

  As shown in Table 2, even when the carbon black is changed from FEF to HAF, the rubber wet masterbatch and the thiosulfate compound are used in combination, and a remarkable improvement effect is obtained in terms of durability and dynamic ratio with respect to the control. It was. As shown in Table 3, even in the blend system of natural rubber and butadiene rubber, the combined use of a rubber wet masterbatch and a thiosulfate compound has a significant improvement effect in durability and dynamic ratio over the control. It was. As shown in Table 4, even in the case of Example 6 in which the natural rubber derived from the rubber wet masterbatch is less than 25 parts by mass of 100 parts by mass of the rubber component, it is remarkable in durability and dynamic magnification with respect to the control. Improvement effect was obtained.

Claims (4)

A rubber wet masterbatch containing 5 to 100 parts by mass of carbon black with respect to 100 parts by mass of natural rubber obtained by mixing natural rubber latex and a slurry containing carbon black in a liquid phase and drying, and represented by the following formula (1): a thiosulfate compound and / or salt thereof, by blending, the thiosulfate compound and / or a salt thereof to prepare a rubber composition containing 0.05 to 5 parts by mass with respect to 100 parts by mass of the rubber component and vulcanizing the rubber composition, rubber vibration insulator manufacturing method of.

(In formula (1), n represents an integer of 0 to 10.) The method for producing a vibration-proof rubber according to claim 1, wherein at least 10% by mass of the rubber component contained in the rubber composition is a natural rubber derived from the rubber wet masterbatch. The method for producing a vibration-proof rubber according to claim 1 or 2, wherein at least 15% by mass of the carbon black contained in the rubber composition is carbon black derived from the rubber wet masterbatch. The rubber wet masterbatch is prepared by adding at least a part of natural rubber latex when carbon black is dispersed in a dispersion solvent to produce a slurry containing carbon black having natural rubber latex particles attached thereto, The method for producing a vibration-proof rubber according to any one of claims 1 to 3, wherein the slurry and the remaining natural rubber latex are mixed, then coagulated and dried.