JP2015000898A - Vibration-proof rubber composition and vibration-proof rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-proof rubber composition that has a low dynamic magnification, has sufficient support characteristics, and prevents decrease in productivity.SOLUTION: A vibration-proof rubber composition comprises: a rubber component comprising natural rubber; a fatty acid component comprising conjugated fatty acid; and a sulfur atom-containing silane coupling agent.

Description

  The present invention relates to an anti-vibration rubber composition for producing an anti-vibration rubber used for torsional dampers, engine mounts, muffler hangers and the like of automobiles, and an anti-vibration rubber using the same.

  Conventionally, in various vehicles such as automobiles, in order to improve the comfort of passengers, various anti-vibration materials have been arranged at sites that are sources of vibration and noise to reduce the intrusion of vibration and noise into the room. Attempts have been made. For example, for engines that are the main source of vibration and noise, vibrations during engine drive are absorbed by using anti-vibration rubber for components such as torsional dampers, engine mounts, and muffler hangers. Reduces the intrusion of vibration and noise and the spread of noise to the surrounding environment.

  As a basic characteristic of such an anti-vibration rubber, a strength characteristic that supports a heavy object such as an engine and an anti-vibration performance that absorbs and suppresses the vibration are required. As an index representing strength characteristics and vibration isolation performance, a dynamic magnification represented by a ratio of a dynamic spring constant to a static spring constant has been conventionally used. The static spring constant indicates the support performance (hardness), and the dynamic spring constant indicates the vibration transmission cutoff performance. The lower the dynamic magnification, the better the anti-vibration rubber performance.

  Conventionally, various methods for improving the dynamic magnification have been proposed. In Patent Document 1, after carbon black is pulverized by a mill to cause a mechanochemical reaction, this is kneaded with a silane coupling agent and other anti-vibration rubber components, and then vulcanized to obtain an anti-vibration rubber. Manufacturing is described.

  Moreover, in patent document 2, by mix | blending the organic unsaturated fatty acid which contains a predetermined amount of the conjugated dienoic acid which contains at least 1 pair of the 2 or more carbon-carbon double bond in a conjugated relationship in a molecule | numerator in a rubber composition. The dynamic magnification is maintained or improved, and the vulcanization reversion and heat settling are improved.

JP 2009-35578 A JP-A-7-97483

  However, the anti-vibration rubber produced by the conventional anti-vibration rubber composition of Patent Documents 1 and 2 cannot be said to have a sufficiently low dynamic magnification to a practically required level, and the dynamic magnification is still further increased. There is a need for improvement. Further, the method described in Patent Document 1 has a problem that the vibration-proof rubber productivity is lowered because a step of pulverizing is required. On the other hand, even if the dynamic magnification is low, if the static spring constant itself does not satisfy a certain standard, the support characteristics of the anti-vibration rubber are impaired, and the function as the anti-vibration rubber cannot be fully exhibited. There is a fear.

  Accordingly, an object of the present invention is to provide an anti-vibration rubber composition having a low dynamic magnification, sufficient support characteristics, and no reduction in productivity.

  The object is achieved by a vibration-insulating rubber composition comprising a rubber component containing natural rubber, a fatty acid component containing a conjugated fatty acid, and a sulfur atom-containing silane coupling agent.

  The anti-vibration rubber produced from this anti-vibration rubber composition has been found to have sufficient support properties and very low dynamic magnification. Although the detailed reason is not clear, it is considered that the sulfur atom contained in the silane coupling agent and the conjugated double bond contained in the conjugated fatty acid interact with the polymer of the rubber component. And this anti-vibration rubber is obtained by kneading and vulcanizing the above anti-vibration rubber composition by a conventional method, and does not require a separate process compared to the conventional process, so the productivity may be reduced. Absent.

  Preferred embodiments of the vibration-insulating rubber composition of the present invention are as follows.

（式中、
Ｒ^１は、それぞれ独立して、炭素原子数１〜６の二価の炭化水素基を表し、
Ｒ^２は、それぞれ独立して、炭素原子数１〜６のアルコキシ基又は塩素原子を表し、
Ｘは、１〜１０の整数である。）
で表される。
（４）前記共役脂肪酸は、炭素原子数５〜３０のジエン酸である。
（５）前記共役脂肪酸を含む脂肪酸成分に対する前記硫黄原子含有シランカップリング剤の含有量比（硫黄原子含有シランカップリング剤／共役脂肪酸を含む脂肪酸成分）が、０．１〜１０である。 (1) The said sulfur atom containing silane coupling agent contains 0.1-5 mass parts with respect to 100 mass parts of said rubber components.
(2) The conjugated fatty acid is included in an amount of 10 to 90% by mass with respect to the mass of the fatty acid component, and the fatty acid component is included in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.
(3) The sulfur atom-containing silane coupling agent has the following formula (I)

(Where
Each R ¹ independently represents a divalent hydrocarbon group having 1 to 6 carbon atoms;
Each R ² independently represents an alkoxy group having 1 to 6 carbon atoms or a chlorine atom;
X is an integer of 1-10. )
It is represented by
(4) The conjugated fatty acid is a dienoic acid having 5 to 30 carbon atoms.
(5) The content ratio of the sulfur atom-containing silane coupling agent to the fatty acid component containing the conjugated fatty acid (sulfur atom-containing silane coupling agent / fatty acid component containing a conjugated fatty acid) is 0.1 to 10.

  The present invention also provides an anti-vibration rubber using the anti-vibration rubber composition.

  According to the present invention, the rubber component is blended with a fatty acid component containing a conjugated fatty acid and a sulfur atom-containing silane coupling agent, thereby having a low dynamic ratio and ensuring sufficient support characteristics. Rubber can be obtained.

  Hereinafter, the present invention will be described in detail. The anti-vibration rubber composition of the present invention contains a rubber component containing natural rubber as a main component, and further contains a fatty acid component containing a conjugated fatty acid and a sulfur atom-containing silane coupling agent.

  There is no restriction | limiting in particular as natural rubber, The normal natural rubber used for a vibration-proof rubber can be used. Specifically, for example, in sheet rubber (including crepe), RSS (Ribbed Smoked Sheet), White Crepes, Pale Crepes, Este Brown Crepes, Comp Crepes, Thin Brown Crapes (Rimills), Thin A, B For all grades of Flat Bark Crepes, Pure Smoked Blanket Crapes, and block rubber, SMR (Standard Malaysian Rubber), SIR (Indonesian), STR (Thai), SSR (Singapore V) Is mentioned. These may be used alone or in combination of two or more.

  The rubber component may contain a diene synthetic rubber. As the diene synthetic rubber, for example, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), or the like can be used. These can be used individually by 1 type or in mixture of 2 or more types. Among these, butadiene rubber (BR) and styrene-butadiene rubber (SBR) are preferable, and butadiene rubber (BR) is particularly preferable.

  When the rubber component contains a diene synthetic rubber, the mass ratio of the natural rubber to the diene synthetic rubber (natural rubber / diene synthetic rubber) is 99/1 to 50/50, preferably 90/10 to 70/30. is there. Within this range, the anti-vibration rubber is imparted with high durability unique to natural rubber, while the effect of further improving the damping property by the diene-based synthetic rubber can be achieved.

  In the present invention, the sulfur atom-containing silane coupling agent contains a sulfur atom covalently bonded to another atom in the molecule. Moreover, like a normal silane coupling agent, hydrolyzable groups, such as an alkoxy group and a chlorine atom, have couple | bonded with the silicon atom. As a sulfur atom containing silane coupling agent, the silane coupling agent which has a mercapto group in a molecule | numerator, or the silane coupling agent which contains a sulfide bond in a molecule | numerator is mentioned, for example.

  As the sulfur atom-containing silane coupling agent, those represented by the following formula (I) can be preferably used.

（式中、
Ｒ^１は、それぞれ独立して、炭素原子数１〜６の二価の炭化水素基を表し、
Ｒ^２は、それぞれ独立して、炭素原子数１〜６のアルコキシ基又は塩素原子を表し、
Ｘは、１〜１０の整数である。）

(Where
Each R ¹ independently represents a divalent hydrocarbon group having 1 to 6 carbon atoms;
Each R ² independently represents an alkoxy group having 1 to 6 carbon atoms or a chlorine atom;
X is an integer of 1-10. )

R ¹ is preferably an alkylene group having 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms.

R ² is preferably an alkoxy group having 1 to 4 carbon atoms, particularly preferably a methoxy group or an ethoxy group. X is preferably an integer of 2 to 6. Specifically, bis (3-triethoxysilylpropyl) tetrasulfide is preferable.

  The content of the sulfur atom-containing silane coupling agent in the vibration-proof rubber composition of the present invention is preferably 0.1 to 5 parts by mass, particularly 0.5 to 4 parts by mass with respect to 100 parts by mass of the rubber component. Within this range, the effect of reducing the dynamic magnification can be sufficiently obtained.

  The conjugated fatty acid contained in the fatty acid component is a fatty acid having a conjugated double bond in its carbon chain. Examples of the conjugated fatty acid include unsaturated fatty acids having 5 to 30 carbon atoms, preferably 15 to 22 carbon atoms. Moreover, the number of double bonds should just be 2-6, for example. That is, dienoic acid, trienoic acid, tetraenoic acid, pentaenoic acid, and hexaenoic acid can be used. Of these, dienoic acid is preferred.

  Specific examples of conjugated fatty acids include 2,4-pentadienoic acid, 2,4-hexadienoic acid, 2,4-decadienoic acid, 2,4-dodecadienoic acid, α-eryostearic acid, and 9,11-octadecadienoic acid. 10,12-octadecadienoic acid, 9,11,13-octadecatrienoic acid, 9,11,13,15-octadecatetraenoic acid, and the like. These conjugated fatty acids contain 1 in the fatty acid component. Species may be present, or two or more kinds may be present. Among the exemplified conjugated fatty acids, 9,11-octadecadienoic acid is particularly preferable.

  As the fatty acid component containing a conjugated fatty acid, for example, dehydrated castor oil fatty acid obtained by dehydrating a fatty acid obtained by saponifying castor oil can be preferably used. The dehydrated castor oil fatty acid includes octadecadienoic acid derived from ricinoleic acid in the constituent components of castor oil. This octadecadienoic acid includes both 9,11-octadecadienoic acid having a conjugated double bond in the carbon chain and 9,12-octadecadienoic acid that is not. In addition to octadecadienoic acid, dehydrated castor oil fatty acid includes other fatty acids (oleic acid, linoleic acid, palmitic acid, stearic acid, etc.) in the constituents of castor oil.

  The content ratio of the conjugated fatty acid in the fatty acid component is 10 to 90% by weight, particularly 20 to 80% by weight, based on the total mass of the fatty acid component.

  And the preferable content of the fatty acid component in the vibration-proof rubber composition of the present invention is 1 to 10 parts by mass, preferably 2 to 10 parts by mass, particularly preferably 5 to 10 parts by mass with respect to 100 parts by mass of the rubber component. is there. If the amount is less than this range, the effect of lowering the dynamic magnification may not be sufficiently obtained. If the amount is more than this range, the vibration isolating rubber composition may not be sufficiently kneaded.

  The anti-vibration rubber composition of the present invention includes a sulfur atom-containing silane coupling agent and a fatty acid component containing a conjugated fatty acid, so that a sufficient anti-vibration property is ensured and an anti-vibration rubber having a low dynamic ratio is obtained. Can do.

  Here, the content ratio of the sulfur atom-containing silane coupling agent to the fatty acid component containing the conjugated fatty acid (sulfur atom-containing silane coupling agent / fatty acid component containing the conjugated fatty acid) is 0.1 to 10, particularly 0.4 to. 3 is preferred.

  In addition to the components described above, the vibration-proof rubber composition of the present invention includes vulcanizing agents, vulcanization accelerators, vulcanization acceleration aids, fillers, waxes, oils and anti-aging agents that are commonly used in the rubber industry. Additives such as agents are appropriately blended.

  Sulfur can be used as the vulcanizing agent. The compounding amount of sulfur is generally 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of vulcanization accelerators for promoting vulcanization include 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, Nt-butyl-2-benzothia. Benzothiazole vulcanization accelerators such as disulfaneamide, Nt-butyl-2-benzothiazylsulfenamide; guanidine vulcanization accelerators such as diphenylguanidine; tetramethylthiuram disulfide, tetrabutylthiuram disulfide, Thiuraum vulcanization accelerators such as tetradodecyl thiuram disulfide, tetraoctyl thiuram disulfide, tetrabenzyl thiuram disulfide; dithiocarbamates such as zinc dimethyldithiocarbamate; other zinc dialkyldithiophosphates It can be.

  About said vulcanization accelerator, 1 type, such as a sulfenamide type | system | group, a thiuram type | system | group, a thiazole type | system | group, a guanidine type | system | group, a dithiocarbamate type | system | group, may be used independently, and 2 or more types may be used together. . Thiuram and / or thiazole systems with relatively high vulcanization acceleration capacity, and guanidine and / or sulfenamide systems with relatively medium to low vulcanization acceleration capacity for adjustment of vulcanization behavior (speed), etc. A combination of these vulcanization accelerators is preferably employed. Specifically, a combination of tetramethylthiuram disulfide and N-cyclohexyl-2-benzothiazylsulfenamide, a combination of tetrabutylthiuram disulfide and Nt-butyl-2-benzothiazylsulfenamide, dibenzo Examples include combinations of thiazyl disulfide and diphenylguanidine. The blending amount of the vulcanization accelerator is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

  In the present invention, from the viewpoint of further promoting vulcanization, a vulcanization acceleration aid such as zinc white (ZnO) or stearic acid can be blended. The compounding amount of these vulcanization acceleration aids is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount exceeds 10 parts by mass, workability and dynamic magnification may be degraded, and if it is less than 1 part by mass, vulcanization delay may occur.

  Known oils can be used and are not particularly limited. Specifically, process oils such as paraffin oil, vegetable oils such as palm oil, synthetic oils such as alkylbenzene oil, and the like are used. Can do. In the present invention, paraffin oil can be preferably used. These can be used alone or in combination of two or more. The blending amount of these oils is not particularly limited, but can be approximately 1 to 40 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount deviates from the above range, the kneading workability may be deteriorated.

  As the anti-aging agent, known ones can be used, and are not particularly limited, and examples thereof include a phenol type anti-aging agent, an imidazole type anti-aging agent and an amine type anti-aging agent. The blending amount of these anti-aging agents is usually 2 to 10 parts by mass, preferably 3 to 7 parts by mass with respect to 100 parts by mass of the rubber component.

  Carbon black, silica, or the like can be used as the filler. As the carbon black, known ones can be used, and are not particularly limited, and examples thereof include carbon blacks such as SRF, GPF, FEF, HAF, ISAF, SAF, FT, and MT. In the present invention, FEF can be preferably used. These carbon blacks can be used alone or in combination of two or more.

On the other hand, silica having a BET specific surface area in the range of 70 to 230 m ² / g is preferably used. If this BET specific surface area is 70 m ² / g or more, a good reinforcing effect can be obtained, and deterioration of rubber physical properties and durability can be suppressed. Further, if the BET specific surface area is 230 m ² / g or less, it is possible to suppress poor dispersion of silica in the rubber composition, and as a result, it is possible to suppress deterioration in durability and deterioration of dynamic magnification due to poor dispersion. it can. A more preferable range of this BET specific surface area is 80 to ²⁰⁰ m ² / g.

  The BET specific surface area is measured by the Brunauer, Emmet and Teller (“BET”) method described in “Journal of American Chemical Society (J. Am. Chem. Soc.)”, Vol. 60, page 309. Is the value to be

As the said silica, the various commercially available thing whose BET specific surface area is 70-230 m < ² > / g can be used. The term “silica” in the present invention is a broad concept including silicon dioxide, silicic acid, and silicate containing SiO ₂ in the composition formula, but silicon dioxide which is anhydrous silicic acid has the above-mentioned effects. In particular, silica produced by a wet method such as silica gel is preferred. As the silica as described above, one kind may be used alone, or two or more kinds may be used in combination.

  In the present invention, as the filler, only the above-described carbon black may be used, only silica may be used, or carbon black and silica may be used in combination.

  The blending amount of these fillers is usually 15 to 60 parts by mass, preferably 20 to 50 parts by mass with respect to 100 parts by mass of the rubber component. When the amount exceeds 60 parts by mass, workability may be deteriorated, and when it is less than 15 parts by mass, adhesion may be deteriorated.

  The anti-vibration rubber composition of the present invention is optionally provided with an antioxidant, a foaming agent, a plasticizer, a lubricant, a tackifier, a petroleum resin, an ultraviolet absorber, a dispersant, a compatibilizing agent, and a homogenizing agent. An additive such as an agent may further be included.

  When obtaining the rubber composition of the present invention, there is no particular limitation on the blending method of each of the above components, and all the component raw materials may be blended and kneaded at once, and each component may be divided into two or three stages. You may mix | blend and knead | mix. In the kneading, a kneader such as a roll, an internal mixer, a Banbury rotor or the like can be used. Furthermore, when forming into a sheet shape or a belt shape, a known molding machine such as an extrusion molding machine or a press machine may be used.

  Moreover, there are no particular limitations on the vulcanization conditions for curing the rubber composition, but vulcanization conditions can be generally employed at 140 to 180 ° C. for 5 to 120 minutes.

  The anti-vibration rubber of the present invention is obtained by vulcanizing the rubber composition described above. As the anti-vibration rubber, for example, it is suitably used for torsional dampers, engine mounts, muffler hangers and the like of automobiles. However, it is not limited to these.

  Each material shown in the following table is kneaded and vulcanized with the indicated composition, vulcanized and cured each anti-vibration rubber composition of each Example and Comparative Example, 120 mm long × 120 mm wide × 2 mm thick A sheet molding was prepared. This sheet was used as an anti-vibration rubber evaluation body.

Details of the materials used are as follows.
・ Natural rubber (RSS # 4)
・ Butadiene rubber (JSR "T700")
・ Sulfur atom-containing silane coupling agent (Degussa “SI-69”, bis (3-triethoxysilylpropyl) tetrasulfide)
・ Sulfur atom-free silane coupling agent (“KBE1003”, vinyltriethoxysilane, manufactured by Shin-Etsu Chemical)
・ Carbon (Asahi Carbon “Asahi # 65”, FEF grade carbon black)
・ Silica (Tosoh "ER-R")
・ Stearic acid (“Stearic acid 50S” manufactured by Shin Nippon Chemical Co., Ltd.)
・ Zinc flower (Hakusui Tech "No.3 Zinc flower")
・ Wax ("Sangite S" manufactured by Seiko Chemical)
Anti-aging agent RD (“NOCRACK 224”, 2,2,4-trimethyl-1,2-dihydroquinoline polymer manufactured by Ouchi Shinsei Chemical Industry)
Anti-aging agent 6C (“Nocrack 6C” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine)
・ Dehydrated castor oil fatty acid (“DCO-FA” manufactured by Ito Oil Co., Ltd., fatty acid component containing 9,11-octadecadienoic acid as a conjugated fatty acid in an amount of 35% by weight)
・ Naphthenic oil (“Diana Process Oil NS-100” manufactured by Idemitsu Kosan Co., Ltd.)
・ Aroma oil (“Diana Process Oil AH-24” manufactured by Idemitsu Kosan Co., Ltd.)
・ Sulfur (Tsurumi Chemical "powder sulfur")
・ Vulcanization accelerator (“Noxeller CZ-G”, N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd.)

<Evaluation method>
The following evaluation test was performed on the evaluation body of the vibration-proof rubber produced above.
-Hardness Hd (-) was measured based on JIS K 6253 (type A).
-Static spring constant (Ks), dynamic spring constant (Kd), and dynamic magnification (Kd / Ks) were based on JIS K 6385, and Kd was measured at 100 Hz.

  The 1 / (Kd / Ks ^ 2) value indicates the value of the dynamic magnification (Kd / Ks) with respect to the static spring constant (Ks), and is a numerical value of the relationship between the magnitude of the static spring constant and the dynamic magnification. is there. A higher value indicates a lower actual dynamic magnification.

  INDEX is 1 / (Kd / Ks ^ 2) of each of the corresponding examples and comparative examples when the value of 1 / (Kd / Ks ^ 2) of Comparative Examples 1A, 2A, 3A and 4A is 100, respectively. Is an index display of the value of.

  In the following table, Comparative Examples 1A to G and Examples 1A to F are blended systems using carbon as a filler, and Comparative Examples 2A and 2A are blended systems using silica as a filler. Example 3A and Examples 3A-B are compounding systems using both carbon and silica as fillers, and Comparative Example 4A and Example 4A are compounding systems using both natural rubber and butadiene rubber as rubber components. .

<Evaluation results>
In the carbon compounding systems of Comparative Examples 1A to G and Examples 1A to F, when both the sulfur atom-containing silane coupling agent and dehydrated castor oil fatty acid are contained, the dynamic ratio is low, and 1 / (Kd / Ks It was observed that the value of ^ 2) was improved. In particular, the INDEX of Examples 1A to F is prominent as compared with the case where the dehydrated castor oil fatty acid is blended alone (Comparative Example 1C) and the case where the sulfur atom-containing silane coupling agent is blended alone (Comparative Example 1F). It has been observed that

  Similarly, when both the sulfur atom-containing silane coupling agent and dehydrated castor oil fatty acid are contained as in the compositions of Examples 2A, 3A, 3B, and 4A, the dynamic ratio is low, and corresponding comparative examples. It was recognized that the value of 1 / (Kd / Ks ^ 2) was improved with respect to 2A, 3A and 4A.

Claims (7)

  An anti-vibration rubber composition comprising a rubber component containing natural rubber, a fatty acid component containing a conjugated fatty acid, and a sulfur atom-containing silane coupling agent.   2. The vibration-proof rubber composition according to claim 1, wherein the sulfur atom-containing silane coupling agent is contained in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component. The conjugated fatty acid is contained in an amount of 10 to 90% by mass with respect to the mass of the fatty acid component,
The anti-vibration rubber composition according to claim 1 or 2, wherein the fatty acid component contains 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The sulfur atom-containing silane coupling agent has the following formula (I)

(Where
Each R ¹ independently represents a divalent hydrocarbon group having 1 to 6 carbon atoms;
Each R ² independently represents an alkoxy group having 1 to 6 carbon atoms or a chlorine atom;
X is an integer of 1-10. )
The anti-vibration rubber composition according to any one of claims 1 to 3, wherein   The vibration-insulating rubber composition according to any one of claims 1 to 4, wherein the conjugated fatty acid is a dienoic acid having 5 to 30 carbon atoms.   The content ratio of the sulfur atom-containing silane coupling agent to the fatty acid component containing the conjugated fatty acid (sulfur atom-containing silane coupling agent / fatty acid component containing a conjugated fatty acid) is 0.1 to 10. The anti-vibration rubber composition according to any one of claims 1 to 5.   An anti-vibration rubber comprising the anti-vibration rubber composition according to any one of claims 1 to 6.