Method for manufacturing a rubber composition for vibration-damping rubber.

Abstract

To provide a method for manufacturing a rubber composition for vibration-damping rubber that allows for a lower dynamic magnification of the final vibration-damping rubber while maintaining a certain degree of rubber hardness. [Solution] A method for producing a rubber composition for vibration-damping rubber containing at least diene rubber, silica, and a silane coupling agent, wherein the diene rubber contains at least natural rubber, and the silica has a BET specific surface area of ​​80 m². 2 A method for producing a rubber composition for vibration-damping rubber, comprising a non-pro step of kneading at least the diene rubber, silica, and silane coupling agent, wherein the composition is less than or equal to / g, and the non-pro step is a step of kneading for a kneading time of 90 to 150 seconds while maintaining a kneading temperature of 150 to 160°C.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a rubber composition for vibration-damping rubber, and more particularly to a method for producing a rubber composition that can be suitably used as a vibration-damping member such as an engine mount for an automobile. [Background technology]

[0002] In recent years, automobiles have become more powerful while also being required to be quiet. Therefore, considering the need for quietness, there has been a demand for the development of vibration-damping rubber compositions that exhibit small changes in the dynamic spring constant of the rubber.

[0003] Patent Document 1 below describes an anti-vibration rubber composition comprising a rubber component obtained by mixing solution polymerized end-modified SBR and butyl rubber, silica gel, a silane coupling agent, sulfur, and at least one of specific bismaleimide compounds, wherein the solution polymerized end-modified SBR contains epoxy groups and amino groups as functional groups, and the amount of each component in the rubber component is 80 to 20% by weight of solution polymerized end-modified SBR and 20 to 80% by weight of butyl rubber.

[0004] Patent Document 2 below describes an anti-vibration rubber composition in which the rubber component consists solely of diene rubber, and which contains carbon black, silica, and a silane coupling agent (excluding silane coupling agents selected from the group of aminoalkylalkoxysilane, aminoarylalkoxysilane, and aminoaralkylalkoxysilane) as fillers, wherein the diene rubber is natural rubber (excluding epoxidized natural rubber), butadiene rubber, styrene-butadiene rubber (SBR), isoprene rubber, styrene-isoprene copolymer, isobutylene-isoprene rubber, acrylonitrile-butadiene rubber, acrylate butadiene rubber, and modified versions of these natural or synthetic rubbers with altered molecular chain ends. The present invention describes a vibration-damping rubber composition that is a mixture of one or more types selected from the group, wherein 70% or more by mass of the rubber component consists of the natural rubber, the silica is silica gel satisfying a nitrogen adsorption specific surface area (BET method) in the range of 80 to 230 m2 / g, the carbon black is at least one type selected from the group of SRF, GPF, FEF, HAF, ISAF, FT, and MT, the amount of carbon black and silica blended is 10 to 80 parts by mass each per 100 parts by mass of the rubber component, and furthermore, the blending ratio of carbon black (a) to silica (b) is (a) / (b) = 40 / 60 to 20 / 80 (by mass ratio), and is used as vibration-damping rubber for automobiles. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5133503 [Patent Document 2] Patent No. 6597834 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Regarding the above-mentioned prior art, the present inventors have conducted thorough studies and found that there is room for further improvement in reducing the dynamic magnification of the final vibration-damping rubber while maintaining a certain degree of rubber hardness.

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide a method for producing a rubber composition for vibration-damping rubber that can reduce the dynamic ratio of the vibration-damping rubber obtained in the end, while maintaining a certain degree of rubber hardness. [Means for solving the problem]

[0008] The above problems can be solved by the following configuration. That is, the present invention is a method for producing a rubber composition for vibration-damping rubber containing at least a diene rubber, silica, and a silane coupling agent, wherein the diene rubber contains at least natural rubber, and the silica has a BET specific surface area of ​​80 m². 2 The present invention relates to a method for producing a rubber composition for vibration-damping rubber (1), characterized in that the composition is less than or equal to / g and includes a non-pro step of kneading at least the diene rubber, the silica, and the silane coupling agent, wherein the non-pro step is a step of kneading for a kneading time of 90 to 150 seconds while maintaining a kneading temperature of 150 to 160°C.

[0009] In the above method for producing a rubber composition for vibration-damping rubber (1), the method for producing a rubber composition for vibration-damping rubber (2) is preferred, in which the amount of silane coupling agent is 8 to 10% by mass of the amount of silica.

[0010] In the above method for producing a vibration-damping rubber composition (1) or (2), method (3) is preferred, in which the amount of silica added is 20 to 40 parts by mass when the total amount of the diene rubber is 100 parts by mass.

[0011] Of the above methods (1) to (3) for producing a rubber composition for vibration-damping rubber, method (4) is preferred, in which, when the total amount of the diene rubber is 100 parts by mass, the amount of natural rubber added is 70 parts by mass or more.

[0012] In any of the above methods (1) to (4) for producing a rubber composition for vibration-damping rubber, method (5) is preferred, which further contains carbon black, wherein when the total amount of the diene rubber is 100 parts by mass, the amount of carbon black added is 20 to 40 parts by mass.

[0013] In the above method for manufacturing the vibration-damping rubber composition (5), the carbon black has a BET specific surface area of ​​80 m². 2 A method for producing a rubber composition for vibration-damping rubber that is less than or equal to / g (6) is preferred. [Effects of the Invention]

[0014] According to the method for producing a rubber composition for vibration-damping rubber of the present invention, it is possible to produce a rubber composition for vibration-damping rubber that can be used as a raw material for vibration-damping rubber, while maintaining a certain degree of rubber hardness, and which can ultimately be used to reduce the dynamic magnification of the vibration-damping rubber obtained. [Modes for carrying out the invention]

[0015] The present invention relates to a method for producing a rubber composition for vibration-damping rubber, which comprises a diene rubber, silica, and a silane coupling agent.

[0016] Diene rubbers, which are one of the raw materials for the method of producing a rubber composition for vibration-damping rubber according to the present invention, include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, and styrene-isoprene-butadiene copolymer rubber. These can be used individually or in combination of two or more. In the non-pro step, in which natural rubber, silica, and a silane coupling agent are kneaded, gelation of the rubber may occur depending on the kneading conditions, which not only worsens the dispersibility of silica but may also render the rubber composition unusable. However, in the method of producing a rubber composition for vibration-damping rubber according to the present invention, by optimizing the non-pro step, it is possible to produce a rubber composition for vibration-damping rubber that can be used as a raw material for vibration-damping rubber while suppressing the gelation of natural rubber, and ultimately resulting in a vibration-damping rubber with a low dynamic ratio. Therefore, in the present invention, it is preferable to use natural rubber as a raw material, and when the total amount of diene rubber is 100 parts by mass, it is more preferable that the amount of natural rubber is 70 parts by mass or more, and particularly preferable that it is 100 parts by mass.

[0017] Silica, one of the raw materials for the method of producing the vibration-damping rubber composition according to the present invention, can be wet silica, dry silica, sol-gel silica, or surface-treated silica, which are commonly used for rubber reinforcement. Among these, wet silica is preferred. However, in the method of producing the vibration-damping rubber composition according to the present invention, the BET specific surface area is 80 m². 2 Use silica with a BET specific surface area of ​​80 m² or less. 2 When silica exceeding 1g / g is used, the dispersibility of silica tends to deteriorate, and the resulting vibration-damping rubber may not achieve sufficient low dynamic ratio. In the method for producing the vibration-damping rubber composition according to the present invention, it is more preferable that the amount of silica blended is 20 to 40 parts by mass when the total amount of diene rubber is 100 parts by mass.

[0018] One of the raw materials for the method of manufacturing a rubber composition for vibration isolation rubber according to the present invention, the silane coupling agent, is not particularly limited as long as it contains sulfur in the molecule, and various silane coupling agents blended with silica in the rubber composition can be used. For example, bis(3-triethoxysilylpropyl)tetrasulfide (e.g., "Si69" manufactured by Evonik Industries), bis(3-triethoxysilylpropyl)disulfide (e.g., "Si75" manufactured by Evonik Industries), bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)disulfide and other sulfide silanes, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane and other mercapto silanes, 3-octanoylthio-1-propyltriethoxysilane, 3-propionylthiopropyltrimethoxysilane and other protected mercapto silanes can be mentioned. The blending amount of the silane coupling agent is preferably 8 to 10% by mass when the total amount of silica is 100% by mass.

[0019] In the method for manufacturing a rubber composition for vibration isolation rubber according to the present invention, it is preferable to further blend carbon black as a raw material in the rubber composition for vibration isolation rubber. As the carbon black, for example, in addition to carbon black used in the normal rubber industry such as SAF, ISAF, HAF, FEF, GPF, etc., conductive carbon black such as acetylene black and ketjen black can be used. However, from the viewpoint of solving the problem, the BET specific surface area of the carbon black used as a raw material is preferably 80 m 2 / g or less. In the rubber composition according to the present invention, when the total amount of the diene rubber is 100 parts by mass, the content of carbon black is preferably 20 to 40 parts by mass.

[0020] The manufacturing method of the rubber composition for vibration isolation rubber according to the present invention has a non-pro kneading step of kneading at least a diene rubber, silica, and a silane coupling agent. The non-pro kneading step may be performed only once, or may be performed multiple times to improve the dispersibility of silica in the rubber.

[0021] In the manufacturing method of the rubber composition for vibration isolation rubber according to the present invention, in the non-pro kneading step, kneading is performed for 90 to 150 seconds while maintaining the kneading temperature in the range of 150 to 160°C. If the kneading time is less than 90 seconds while the kneading temperature is set to 150 to 160°C, the reaction between silica and the silane coupling agent becomes insufficient, and due to the deterioration of the dispersibility of silica, the low dynamic magnification of the finally obtained vibration isolation rubber cannot be achieved. On the other hand, if the kneading time exceeds 150 seconds while the kneading temperature is set to 150 to 160°C, the gelation of natural rubber may progress, and again, the low dynamic magnification of the finally obtained vibration isolation rubber cannot be achieved. From the perspective of solving the problem, in the manufacturing method of the rubber composition for vibration isolation rubber according to the present invention, it is more preferable to perform kneading for 110 to 130 seconds in the non-pro kneading step while maintaining the kneading temperature in the range of 150 to 160°C.

[0022] In the manufacturing method of the rubber composition for vibration isolation rubber according to the present invention, after the non-pro kneading step, a final step of blending vulcanizing agents such as sulfur and vulcanization accelerators is provided.

[0023] Sulfur may be ordinary sulfur for rubber, and for example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur, etc. can be used. In the rubber composition according to the present invention, when the total amount of the diene rubber is 100 parts by mass, the sulfur content is preferably 0.1 to 5.0 parts by mass.

[0024] As the vulcanization accelerator, vulcanization accelerators such as sulfenamide-based vulcanization accelerators, thiuram-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiourea-based vulcanization accelerators, guanidine-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators, which are commonly used for rubber vulcanization, may be used alone or mixed as appropriate. In the rubber composition according to the present invention, when the total amount of the diene rubber is 100 parts by mass, the content of the vulcanization accelerator is more preferably 0.1 to 5.0 parts by mass.

[0025] In the method for producing a rubber composition for vibration-damping rubber according to the present invention, compounding agents known to those skilled in the art, such as antioxidants, zinc oxide, stearic acid, softeners such as waxes and oils, and processing aids, can be added in either the pre-processing step or the final processing step, or in any other step.

[0026] Examples of anti-aging agents commonly used for rubber include aromatic amine-based anti-aging agents, amine-ketone-based anti-aging agents, monophenol-based anti-aging agents, bisphenol-based anti-aging agents, polyphenol-based anti-aging agents, dithiocarbamate-based anti-aging agents, and thiourea-based anti-aging agents.

[0027] In the method for producing a rubber composition for vibration-damping rubber according to the present invention, the non-pro step, the final step, and an additional step of mixing in an optional compounding agent can be carried out using a kneader commonly used in the rubber industry, such as a Banbury mixer, kneader, or roll.

[0028] The method for producing a rubber composition for vibration-damping rubber according to the present invention makes it possible to produce a rubber composition for vibration-damping rubber that can be used as a raw material for vibration-damping rubber that can ultimately be made to have a low dynamic ratio while maintaining a certain degree of rubber hardness. Therefore, the vibration-damping rubber that is ultimately produced can be suitably used for vibration-damping and seismic isolation rubber such as vibration-damping rubber for automobiles such as engine mounts, torsional dampers, body mounts, cap mounts, member mounts, strut mounts, and muffler mounts, as well as vibration-damping rubber for railway vehicles, vibration-damping rubber for industrial machinery, seismic isolation rubber for buildings, and seismic isolation rubber bearings, and is particularly useful as a component of vibration-damping rubber for automobiles that requires a low dynamic ratio. [Examples]

[0029] The present invention will be described in more detail below by illustrating some embodiments.

[0030] (Manufacturing of rubber compositions) Examples 1-4 and Comparative Examples 1-6 For 100 parts by mass of the diene rubber, a rubber composition was formulated according to the formulation in Table 1, and the rubber composition was adjusted by the production method of the rubber composition for vibration isolators according to Examples 1 to 4 and Comparative Examples 1 to 6 using an ordinary Banbury mixer. Each compounding agent described in Table 1 is shown below.

[0031] · Natural rubber; RSS#3 · Carbon black (FEF); trade name "Seast SO", manufactured by Tokai Carbon Co., Ltd., BET specific surface area is 42 m 2 / g · Carbon black (GPF); trade name "Seast V", manufactured by Tokai Carbon Co., Ltd., BET specific surface area is 27 m 2 / g · Silica (1); trade name "Nipsil ER", manufactured by Tosoh Silica Corporation, BET specific surface area is 100 m 2 / g · Silica (2); trade name "Nipsil RS150", manufactured by Tosoh Silica Corporation, BET specific surface area is 80 m 2 / g · Silica (3); trade name "ULTRASIL360", manufactured by Evonik Industries AG, BET specific surface area is 55 m 2 / g · Silane coupling agent; trade name "Si69", manufactured by Evonik Industries AG · Zinc oxide; trade name "Zinc white No. 3", manufactured by Mitsui Mining & Smelting Co., Ltd. · Stearic acid; trade name "Lunac S20", manufactured by Kao Corporation · Wax; trade name "OZOACE2701", manufactured by Nippon Seiro Co., Ltd. · Antioxidant (1); trade name "Nocrack 6C", manufactured by Ouchi Shinko Chemical Industry Co., Ltd. · Antioxidant (2); trade name "Antage RD", manufactured by Kawaguchi Chemical Industry Co., Ltd. · Sulfur; trade name "5% oil-treated sulfur", manufactured by Hosoi Chemical Industry Co., Ltd. · Vulcanization accelerator (1); trade name "CZ", manufactured by Ouchi Shinko Chemical Industry Co., Ltd. · Vulcanization accelerator (2); trade name "Noxeller TS", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0032] The rubber compositions produced by the methods for manufacturing vibration-damping rubber compositions described in Examples 1-4 and Comparative Examples 1-6 were evaluated under the following conditions. The vulcanization conditions during the production of the vulcanized rubber were heating and vulcanizing at 170°C for 13 minutes.

[0033] [Hardness of vibration-damping rubber] The JIS Type A hardness of vulcanized rubber was evaluated based on JIS-K 6253. The evaluation was performed using an index, with the hardness of the vibration-damping rubber manufactured in Comparative Example 1 set to 100. A difference of ±3 from the hardness of the vibration-damping rubber in Comparative Example 1 indicates that the rubber hardness has been maintained. The results are shown in Table 1.

[0034] [Dynamic magnification of vibration-damping rubber] (Static spring constant (Ks)) Each rubber composition was press-molded while being vulcanized at 170°C for 12 minutes to produce cylindrical vulcanized rubber samples (50 mm in diameter, 25 mm in height). The prepared test pieces were compressed twice by 5 mm in the axial direction of the cylinder, and the deflection loads of 1.25 mm and 3.75 mm were measured from the load deflection curve when the strain recovered. The static spring constant (Ks) (N / mm) was calculated from these values. (Dynamic spring constant (Kd)) The test piece used to measure the static spring constant (Ks) was compressed by 2.5 mm in the axial direction of the cylinder. A constant displacement harmonic compression vibration with an amplitude of 0.05 mm at a frequency of 100 Hz was applied from below, centered on this 2.5 mm compression point. The dynamic load was detected by an upper load cell, and the dynamic spring constant (Kd) (N / mm) was calculated in accordance with JIS-K 6394. (Dynamic magnification: Kd / Ks) The dynamic magnification was calculated using the following formula. (Dynamic Magnification) = (Dynamic Spring Constant (Kd)) / (Static Spring Constant (Ks)) The dynamic magnification of the vibration-damping rubber in Comparative Example 1 was set to 100 for index evaluation. A lower value indicates a lower dynamic magnification of the vibration-damping rubber, meaning that the reduction in dynamic magnification has been sufficiently achieved. The results are shown in Table 1.

[0035] [Table 1]

[0036] From the results in Table 1, it can be seen that the vulcanized rubber (vibration-damping rubber) produced by the manufacturing methods for vibration-damping rubber compositions according to Examples 1 to 4 achieves a low dynamic magnification while maintaining a certain degree of rubber hardness. On the other hand, it can be seen that the vulcanized rubber (vibration-damping rubber) produced by the manufacturing methods for vibration-damping rubber compositions according to Comparative Examples 2 to 3 does not achieve a low dynamic magnification because the rubber composition does not contain silica. Furthermore, the vulcanized rubber (vibration-damping rubber) produced by the manufacturing method for vibration-damping rubber compositions according to Comparative Example 4 has a BET specific surface area of ​​100 m² of silica contained in the rubber composition. 2 Since the value exceeds / g, it is clear that the reduction in dynamic magnification has not been achieved. Furthermore, in the vulcanized rubber (vibration-damping rubber) of the rubber composition produced by the manufacturing method of the vibration-damping rubber composition according to Comparative Examples 5 and 6, it is clear that the reduction in dynamic magnification has not been achieved because the mixing time at a mixing temperature of 150 to 160°C during the non-progressive process was not controlled within an appropriate range.

Claims

1. A method for producing a rubber composition for vibration-damping rubber containing at least diene rubber, silica, and a silane coupling agent, The aforementioned diene rubber contains at least natural rubber, The silica has a BET specific surface area of ​​80 m². 2 Items less than or equal to / g, The process includes at least a non-processing step of kneading the diene rubber, the silica, and the silane coupling agent, A method for producing a rubber composition for vibration-damping rubber, characterized in that the non-processing step is a step of kneading for a kneading time of 90 to 150 seconds while maintaining a kneading temperature of 150 to 160°C.

2. A method for producing a rubber composition for vibration-damping rubber according to claim 1, wherein the amount of the silane coupling agent is 8 to 10% by mass of the amount of the silica.

3. A method for producing a vibration-damping rubber composition according to claim 1, wherein the amount of silica added is 20 to 40 parts by mass when the total amount of the diene rubber is 100 parts by mass.

4. A method for producing a vibration-damping rubber composition according to claim 1, wherein the amount of natural rubber added is 70 parts by mass or more when the total amount of the diene rubber is 100 parts by mass.

5. A method for producing a vibration-damping rubber composition containing carbon black, wherein the amount of carbon black added is 20 to 40 parts by mass when the total amount of the diene rubber is 100 parts by mass.

6. The carbon black has a BET specific surface area of ​​80 m². 2 A method for producing the vibration-damping rubber composition according to claim 5, wherein the amount is less than or equal to / g.

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