JP2007145986A - Support rubber composition and rubber support using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a support rubber composition to become rubber having a stable modulus throughout a year and to provide a rubber support using the same. <P>SOLUTION: The support rubber composition comprises 100 parts by mass of diene-based rubber containing ≥50 mass% of natural rubber, 5-50 parts by mass of silica, a polyol compound in an amount of 5-17 mass% of the silica, a vulcanizing agent and a vulcanization accelerator. The rubber support uses the same. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rubber composition for a bearing and a rubber bearing using the same.

Conventionally, as a rubber composition for rubber support, the thing of patent documents 1-3 is proposed, for example.
Patent Document 1 states that “a seismic isolation structure including a laminated body in which a rubber plate and a hard plate are laminated, and the rubber composition used for the rubber plate includes 100 parts by weight of the base rubber. The base-isolated structure characterized in that 0.1 to 50 parts by weight of polynorbornene rubber is blended.
Patent Document 2 describes “a rubber composition for a laminate comprising a rubber component made of a diene rubber, and containing 10 to 100% by weight of isoprene rubber in the rubber component.”
Patent Document 3 discloses a rubber composition for a large rubber product containing 100 parts by mass of a diene rubber containing 50% by mass or more of natural rubber and 0.1 to 5 parts by mass of a vulcanization accelerator having a specific structure. Things are listed.

JP-A-11-198269 JP 2001-342295 A JP 2005-132913 A

However, the rubber comprising the rubber composition containing silica as described in Patent Document 1 has a modulus that varies depending on the season even in the same composition, that is, the modulus is high in summer when the humidity is high. The present inventors have found that the modulus is low in winter when the temperature is low. It has been found that such a decrease in modulus causes a decrease in horizontal rigidity.
Further, when the rubber composition described in Patent Document 2 or 3 contains silica, it has been found that the rubber made of such a rubber composition has room for improvement in terms of the change in modulus between summer and winter. It was.
Therefore, an object of the present invention is to provide a rubber composition for a bearing that can be a rubber having a stable modulus throughout the year.

  As a result of diligent studies to solve the problems, the present inventor has found that a diene rubber containing a specific amount of natural rubber, a specific amount of silica, a specific amount of a polyol compound, a vulcanizing agent, and a vulcanization accelerator. The present inventors have found that a rubber composition containing can be a rubber having a stable modulus throughout the year, and have completed the present invention.

That is, the present invention provides the following rubber compositions for bearings (1) to (4) and the rubber bearings of (5) below.
(1) 100 parts by mass of a diene rubber containing 50% by mass or more of natural rubber, 5 to 50 parts by mass of silica, a polyol compound in an amount of 5 to 17% by mass of the silica, a vulcanizing agent, and vulcanization acceleration A rubber composition for bearings containing an agent.
(2) The rubber composition for bearings according to (1), wherein the silica content is 5 to 25 parts by mass with respect to 100 parts by mass of the diene rubber.
(3) The rubber composition for bearings according to the above (1) or (2), wherein the polyol compound is diethylene glycol.
(4) The rubber composition for bearings according to any one of (1) to (3), wherein the vulcanization accelerator is represented by the following formula (1).

(In the formula, R ¹ and R ² are each independently a chained aliphatic hydrocarbon group having 1 to 6 carbon atoms which may be branched or a cyclic which may be branched having 3 to 6 carbon atoms. Represents an aliphatic hydrocarbon group.)
(5) A rubber bearing in which a rubber layer made of the rubber composition for bearing according to any one of the above (1) to (4) and a hard layer are alternately laminated.

  The rubber composition for bearings of the present invention can be a rubber having a stable modulus throughout the year.

The present invention will be described in detail below.
The rubber composition for bearings of the present invention comprises 100 parts by mass of a diene rubber containing 50% by mass or more of natural rubber, 5 to 50 parts by mass of silica, a polyol compound in an amount of 5 to 17% by mass of the silica, It contains a vulcanizing agent and a vulcanization accelerator.

The diene rubber will be described below.
The diene rubber used in the rubber composition for bearings of the present invention is not particularly limited as long as it contains 50% by mass or more of natural rubber.

Natural rubber is not particularly limited. For example, a conventionally well-known thing is mentioned.
The amount of natural rubber is preferably 70% by mass or more in the diene rubber from the viewpoint of processability, green strength and vulcanized physical properties of the rubber composition for support.

Examples of rubbers that can be included in the diene rubber other than natural rubber include isoprene rubber (IR), butadiene rubber (BR), 1,2-polybutadiene rubber (1,2-BR), and styrene-butadiene copolymer rubber. (SBR), acrylonitrile-butadiene copolymer rubber (NBR, NIR, NBIR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR), ethylene propylene diene rubber (EPDM), etc. And diene-based synthetic rubbers such as urethane rubber, silicone rubber, acrylic rubber, epoxidized natural rubber, and acrylate butadiene rubber.
Rubbers other than natural rubber can be used alone or in combination of two or more.
Moreover, it is mentioned as one of the aspects with preferable that diene rubber contains natural rubber and diene rubbers other than natural rubber. In such a case, a rubber bearing obtained by alternately laminating a rubber layer composed of a rubber composition for a bearing containing natural rubber and a diene rubber other than natural rubber and a hard layer, the rubber layer and the hard rubber Excellent adhesion to the layer.

Silica will be described below.
The silica used for the rubber composition for bearings of the present invention is not particularly limited. Examples include fumed silica, calcined silica, precipitated silica, ground silica, fused silica, and diatomaceous earth.
Silica can be used alone or in combination of two or more.

  The content of silica is 5 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. In such a range, the resulting rubber has excellent fracture properties. From the viewpoint that the fracture property of the rubber becomes higher, the content of silica is preferably 5 to 25 parts by mass with respect to 100 parts by mass of the diene rubber, and is 5 parts by mass or more and less than 20 parts by mass. Is more preferable.

The polyol compound will be described below.
The polyol compound used in the rubber composition for bearings of the present invention has two or more hydroxy groups. Examples include ethylene glycol, diethylene glycol, and propylene glycol.
Among these, diethylene glycol is preferable from the viewpoint that the modulus of rubber is more stable throughout the year.
Moreover, it is preferable that the molecular weight is 50-500 from a viewpoint that the polyol compound is easy to be mixed and processed into rubber.
The polyol compound preferably has a boiling point of 150 ° C. or higher. In such a range, the rubber composition for support is not volatilized during mixing and vulcanization, and can remain in the composition.
A polyol compound can be used individually or in combination of 2 types or more, respectively.

  The content of the polyol compound is 5 to 17% by mass of the amount of silica. In such a range, the resulting rubber modulus becomes stable throughout the year. From the viewpoint that the modulus of the rubber becomes more stable throughout the year, the content of the polyol compound is preferably 5 to 15% by mass, more preferably 5 to 12% by mass of the amount of silica.

The vulcanizing agent will be described below.
The vulcanizing agent used in the rubber composition for bearings of the present invention is not particularly limited. For example, organic sulfur-containing compounds such as sulfur, tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), dipentamethylene thiuram disulfide (DPTT); organic peroxides such as dicumyl peroxide; quinonedioxime and the like It is done.
Vulcanizing agents can be used alone or in combination of two or more.

  The content of the vulcanizing agent is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the diene rubber from the viewpoint that the vulcanization can sufficiently proceed.

The vulcanization accelerator will be described below.
The vulcanization accelerator used for the rubber composition for bearings of the present invention is not particularly limited. Examples thereof include compounds represented by the following formula (1), sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, dithiocarbamate vulcanization accelerators, and thiuram vulcanization accelerators.

In formula (1), R ¹ and R ² may each independently be a chain aliphatic hydrocarbon group having 1 to 6 carbon atoms which may be branched or a branched chain having 3 to 6 carbon atoms. Represents a good cycloaliphatic hydrocarbon group.
Here, as the chain aliphatic hydrocarbon group having 1 to 6 carbon atoms, specifically, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, Examples include isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group and the like. . The chain aliphatic hydrocarbon group may contain a double bond or a triple bond. Of these, a methyl group and an ethyl group are preferable.
Specific examples of the cyclic aliphatic hydrocarbon group having 3 to 6 carbon atoms that may be branched include cyclopropan-1-yl, cyclobutan-1-yl, and cyclopentan-1-yl. , Cyclohexane-1-yl and the like.

Specific examples of the compound represented by the formula (1) having such a substituent in R ¹ and R ² include 2- (N, N-dimethylthiocarbamoylthio) benzothiazole, 2- ( N, N-diethylthiocarbamoylthio) benzothiazole, 2- (N, N-dicyclohexylthiocarbamoylthio) benzothiazole and the like.

  A commercially available product can be used as the compound represented by the formula (1), and examples thereof include Noxeller 64 (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.).

Specific examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide (CBS, Noxeller CZ; manufactured by Ouchi Shinsei Chemical Co., Ltd.), N-tert-butyl. -2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N, N-dicyclohexyl-2-benzothiazylsulfenamide and the like.
Specific examples of the thiazole vulcanization accelerator include 2- (4′-morpholinodithio) benzothiazole, 2-mercaptobenzothiazole, benzothiazyl disulfide, and the like.

Specific examples of the dithiocarbamate vulcanization accelerator include zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc ethylphenyldithiocarbamate and the like.
Specific examples of the thiuram vulcanization accelerator include tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N), tetramethylthiuram monosulfide (TS), tetraethylthiuram disulfide (TET), and tetramethylthiuram disulfide. (TT), dipentamethylene thiuram hexasulfide (TRA) and the like.

Among these, from the viewpoint that the modulus of the resulting rubber is more stable throughout the year, the compound represented by the formula (1) is preferable, and 2- (N, N-dimethylthiocarbamoylthio) benzothiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole and 2- (N, N-dicyclohexylthiocarbamoylthio) benzothiazole are more preferable.
Vulcanization accelerators can be used alone or in combination of two or more.

  The amount of the vulcanization accelerator is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber, from the viewpoint that the modulus of the resulting rubber is more stable throughout the year. More preferably, it is 3.0 parts by mass.

  The rubber composition for bearings of the present invention can contain additives as necessary in addition to the diene rubber, silica, polyol compound, vulcanizing agent and vulcanization accelerator. Examples of additives include vulcanization accelerators, vulcanization retarders, colorants (pigments), anti-aging agents, fillers (reinforcing agents), softeners, plasticizers, activators, tackifiers, and lubricants. Can be mentioned.

Specific examples of the vulcanization acceleration aid include metal oxides such as zinc white and magnesia; risurge, red lead, calcium hydroxide, fatty acid and the like. These may be used alone or in combination of two or more.
The content of the vulcanization acceleration aid that can be added as desired is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the vulcanization accelerating auxiliary is within this range, it is preferable because vulcanization proceeds sufficiently and a material having high physical properties (for example, excellent modulus and hardness) can be obtained.

Specific examples of the vulcanization retarder include organic acids such as phthalic anhydride, benzoic acid, salicylic acid and acetylsalicylic acid; N-nitroso-diphenylamine, N-nitroso-phenyl-β-naphthylamine, N-nitroso- Nitroso compounds such as polymers of trimethyl-dihydroquinoline; Halides such as trichloromelanin; 2-mercaptobenzimidazole, N-cyclohexylthiophthalimide and the like. These may be used alone or in combination of two or more.
The content of the vulcanization retarder that can be added as desired is preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the vulcanization retarder is within this range, it is preferable because the scorch can be stabilized without inhibiting vulcanization.

Specific examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, ultramarine, bengara, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, and sulfate; azo pigments, phthalocyanine pigments, Quinacridone pigment, quinacridone quinone pigment, dioxazine pigment, anthrapyrimidine pigment, ansanthrone pigment, indanthrone pigment, flavanthrone pigment perylene pigment, perinone pigment, diketopyrrolopyrrole pigment, quinonaphthalone pigment, anthraquinone pigment, thioindigo pigment, benzimidazolone Examples thereof include organic pigments such as pigments and isoindoline pigments. These may be used alone or in combination of two or more.
The content of the colorant that can be added as desired is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the colorant is within this range, it is preferable because the color can be colored without impairing physical properties (for example, modulus, hardness, etc.).

Specific examples of the antioxidant include N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), N, N′-dinaphthyl-p-phenylenediamine (DNPD). ), N-isopropyl-N′-phenyl-p-phenylenediamine (IPPD), styrenated phenol (SP), and the like. These may be used alone or in combination of two or more.
The content of the anti-aging agent that can be added as desired is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the anti-aging agent is within this range, it is preferable because the anti-aging effect can be sufficiently obtained.

Specific examples of the filler include carbon black, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium sulfate, aluminum hydroxide, wax stone clay, Examples include kaolin clay, baked clay, talc, and mica. These may be used alone or in combination of two or more.
The content of the filler that can be added as desired is preferably 20 to 100 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the filler is within this range, it is preferable because sufficient physical properties (for example, elongation at break and hardness) can be obtained.

Specific examples of the softener include plant softeners such as tall oil mainly composed of linoleic acid, oleic acid, and abietic acid, pine tar, rapeseed oil, cottonseed oil, peanut oil, castor oil, palm oil, fuactis; And mineral oil softeners such as paraffinic oil, naphthenic oil, and aromatic oil. These may be used alone or in combination of two or more.
The content of the softening agent that can be added as desired is preferably 1 to 150 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the softening agent is within this range, it is preferable because workability such as mixing and rolling is excellent.

Specific examples of the plasticizer include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate, isodecyl succinate, diethylene glycol dibenzoate, pentaerythritol ester, butyl oleate, methyl acetylricinoleate, phosphorus Examples include tricresyl acid, trioctyl phosphate, trimellitic acid ester, propylene glycol adipate polyester, butylene glycol adipate polyester, and the like. These may be used alone or in combination of two or more.
The content of the plasticizer that can be added as desired is preferably 1 to 150 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the plasticizer is within this range, it is preferable because of excellent workability such as mixing and rolling.

Specific examples of the activator include stearic acid, oleic acid, lauric acid, and zinc stearate. These may be used alone or in combination of two or more.
The content of the activator that can be added as desired is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the activator is within this range, it is preferable because vulcanization proceeds sufficiently.

Specific examples of the tackifier include alkylphenol formaldehyde resins, alkylphenol acetylene resins, coumarone indene resins, xylene formaldehyde resins, polybutenes, and rosin derivatives. These may be used alone or in combination of two or more.
The content of the tackifier that can be added as desired is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the tackifier is within this range, it is preferable because sufficient tackiness can be obtained without impairing processability.

Specific examples of the lubricant include stearic acid metal soap, high melting point wax, low molecular weight polyethylene, and octadecylamine. These may be used alone or in combination of two or more.
The content of the lubricant that can be added as desired is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. If the content of the lubricant is within this range, it is preferable because sufficient fluidity can be obtained.

  The rubber composition for bearings of the present invention is not particularly limited for its production. For example, it can be produced by mixing silica, a polyol compound, a vulcanizing agent and a vulcanization accelerator, and, if necessary, an additive in a diene rubber. Specifically, for example, a diene rubber, silica, a polyol compound, a vulcanizing agent and a vulcanization accelerator, and an additive that can be used as necessary are used in a roll, a kneader, an extruder, a universal agitator. And a method of producing by kneading using a twin screw extruder, a Banbury mixer or the like.

Next, the rubber bearing of the present invention will be described below.
The rubber bearing of the present invention is obtained by alternately laminating a rubber layer made of the rubber composition for a bearing of the present invention and a hard layer.

The rubber bearing of the present invention will be described in detail with reference to the accompanying drawings. The rubber bearing of the present invention is not limited to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a rubber bearing of the present invention.
In FIG. 1, 10 is a rubber bearing. The rubber bearing 10 is a laminate of flanges 11 and 12, a soft layer 13 and a hard layer 14. Metal flanges 11 and 12 are disposed on the upper and lower surfaces of the rubber bearing 10. A plurality of soft layers 13 and hard layers 14 are alternately laminated between the flanges 11 and 12. The soft layer 13 can be constituted by vulcanizing and molding the support rubber composition of the present invention. The outer periphery of the laminate is covered with a coating layer 15 made of the same rubber composition as that of the soft layer 13.
Further, the hard layer 14 used in the rubber support 10 is not particularly limited as long as it has a higher hardness than the soft layer 13. Examples of the material include metals, ceramics, and plastics. One preferred embodiment is to use a steel plate.

Since the soft layer 13 can be obtained by vulcanizing and molding the support rubber composition of the present invention, the modulus of the rubber becomes stable throughout the year. This is very useful because the horizontal stiffness of the rubber does not change throughout the year and tends to be constant.
The use of the rubber bearing of the present invention is not particularly limited. For example, it can be used in various types of vibration energy absorbing devices such as seismic isolation, seismic isolation, and seismic isolation (for example, support for road bridges, basic seismic isolation for bridges and buildings, and seismic isolation for detached houses).

  The rubber bearing of the present invention is not particularly limited for its production. For example, the rubber composition for support of the present invention is kneaded using a roll, kneader, extruder, universal agitator, twin screw extruder, Banbury mixer, etc., and the obtained kneaded product is preferably 120 to 190 ° C. Can be produced by heating and vulcanizing at a temperature of 135 to 150 ° C.

The production of the rubber bearing includes a rolling process for rolling the rubber composition for a bearing of the present invention into a sheet, and a laminated body forming process in which a rubber sheet and a hard layer obtained by the rolling process are laminated to form a laminated body. And a vulcanization adhesion step in which the laminate formed by the laminate formation step is bonded by vulcanization.
The (1) rolling step, (2) laminate forming step, and (3) vulcanization bonding step will be described in detail below.

(1) Rolling process A rolling process is a process of rolling the rubber composition for support of the present invention into a sheet form in an unvulcanized state, and thereby a rubber sheet is obtained.
The sheet obtained by rolling generally has a length of 50 to 70 m × width of 60 to 100 cm × thickness of 0.2 to 0.5 cm when a rolling roll is used. In order to obtain a rubber sheet to be used, the obtained sheets can be stacked so as to have a predetermined thickness (for example, 2.5 cm). In addition, if the sheet | seat obtained by rolling has the thickness of the rubber sheet used for a rubber bearing, it is not necessary to pile up a sheet | seat.
Further, after the rolling process, if necessary, there may be a process of appropriately chopping the length or width of the rubber sheet in order to obtain a rubber sheet shape suitable for use in the laminate forming process described later. .

(2) Laminate Forming Step The laminate forming step is a step of laminating a rubber sheet and a hard layer obtained by a rolling step, whereby a laminate is formed. Here, the hard layer is the same as described above.

(3) Vulcanization adhesion process A vulcanization adhesion process is a process of making it adhere by vulcanizing the layered product formed by the layered product formation process. It is preferable to vulcanize at 120 to 190 ° C, and more preferable to vulcanize at 135 to 150 ° C. As a result, a rubber bearing in which the rubber sheet forming the laminate and the hard layer are vulcanized and bonded is manufactured.
Specifically, for example, a rubber bearing having a length × width × height of 100 cm × 100 cm × 35 cm can be produced by vulcanization at a temperature of 135 ° C. for 10 hours.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
1. Preparation of rubber composition for bearing Natural rubber (NR), carbon black (CB), silica, zinc oxide, stearic acid, anti-aging agent, aroma oil, polyol compound with compositional components (parts by mass) shown in Table 1 below Then, an unvulcanized rubber composition was prepared by blending sulfur and a vulcanization accelerator.

Each component in Table 1 uses RSS3 as natural rubber, Showa Black S118 (made by Showa Cabot) as carbon black, Toxeal GU (made by Tokuyama) as silica, and zinc oxide as zinc oxide. 3 types (manufactured by Shodo Chemical Co., Ltd.), stearic acid (manufactured by Nippon Oil & Fats Co., Ltd.), Santoflex 6PPD (manufactured by Flexis Co.) as an anti-aging agent, Extract 4 (manufactured by Showa Shell Sekiyu KK) Diethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) was used as the polyol compound, oil-treated sulfur (manufactured by Karuizawa Seisakusho) was used as the sulfur, and Noxeller 64 (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) was used as the vulcanization accelerator.
Silica used was dried for 5 days under conditions of 10 ° C. and 20% RH.

2. Evaluation (1) Tensile Strength and Elongation Each rubber composition obtained from Table 1 was measured for tensile strength and elongation according to JIS K6251-1993. The vulcanization conditions at that time were a vulcanization temperature of 150 ° C. and a vulcanization time of 15 minutes. The results are shown in Table 1.

3. Modulus test assuming fluctuation of humidity depending on season (1) Preparation of rubber composition for bearing Example 1 in which silica (dried silica) contained in each rubber composition for bearing shown in Table 1 was replaced with humidified silica -3 and compositions of Comparative Examples 1-2 were prepared. Table 2 shows the blending amounts of dry silica and humidified silica in each composition.
In the present invention, by using a dry or humidified silica as the silica contained in the same composition, it is possible to simulate the variation of the modulus in the summer and winter environments of the same bearing rubber composition. I am testing. When dry silica is contained, the humidity of the winter environment (humidity is low) is assumed, and when humidified silica is contained, the humidity of the summer environment (high humidity) is assumed.
The dried silica used was dried as described above.
As the humidified silica, Tokusil GU (manufactured by Tokuyama) was humidified by placing it at 30 ° C. and 80% RH for 2 days.

(2) Measurement of M ₁₀₀ of M ₁₀₀ is in accordance with JIS K6251-1993, and a dry silica-containing composition with a humidified silica-containing composition of each example vulcanization temperature 0.99 ° C., vulcanization time of 15 minutes Vulcanization was performed under the conditions, and the obtained vulcanized rubber was cut into dumbbell-shaped test pieces (dumbbell-shaped No. 3) having a thickness of 2 mm, and M ₁₀₀ of the obtained dumbbell-shaped test pieces was measured. The results are shown in Table 2.
Table 2 shows the value of M ₁₀₀ ratio (winter / summer Mod ratio) when dry silica (winter) is used with respect to M ₁₀₀ when humidified silica (summer) is used as an evaluation of seasonal physical property fluctuations. . When the winter / summer Mod ratio is 0.95 or more, ◎, when 0.90 or more and less than 0.95, ◯, and when less than 0.90, ×.
Further, the torque when a rubber composition for support containing dry silica as silica was vulcanized at a vulcanization temperature of 150 ° C. was measured over time using a rheometer (manufactured by Toyo Seiki Co., Ltd., disk rheometer). Attached FIGS. 2 to 7 are charts of vulcanization curves showing the results.

  As is apparent from the results shown in Table 1, Examples 1 to 3 have higher tensile strength than Comparative Example 2. In addition, the rubber compositions for bearings of Examples 1 to 3 have higher elongation than Comparative Example 1.

The present inventor found from the results of Comparative Example 2, FIG. 5 and FIG. 6 that the change in the modulus of the rubber composition for the bearing due to the season is due to humidity. That is, even when the rubber composition for the bearing having the same composition is used, the modulus of the rubber composition for the bearing is high in the summer when the humidity is high, and the modulus of the rubber composition for the bearing is low in the winter when the humidity is low. The present inventor has found that such a decrease in the modulus in winter is likely to cause a decrease in the horizontal rigidity, so that it is necessary to stabilize the modulus at a summer level throughout the year.
As apparent from the results shown in Table 2, in Examples 1 to 3, the modulus shows a high value regardless of the amount of moisture contained in the composition. From this, it can be said that the modulus of the rubber obtained from the rubber composition for bearings of the present invention is stable throughout the year.
Further, as is apparent from the charts shown in FIGS. 2 to 4 (using dry silica), the value of the torque (modulus equivalent) of the rubber obtained from the rubber composition for bearing of the present invention increases the amount of the polyol compound. As the torque increases, the torque value is substantially equal to that of Comparative Example 2 (humidified silica is used) in FIG.

  Regarding the change in the modulus depending on the season, in the summer, the rubber composition for bearings contains a lot of moisture, and the silica in the composition is in a state of hydrogen bonding with a relatively large amount of moisture, whereas in the winter, In the rubber composition for bearings, water is low and silica is combined with a vulcanization accelerator instead of water, which causes a decrease in the vulcanization speed and a decrease in the crosslinking density of the rubber composition, resulting in a decrease in modulus. The inventors infer that this is the case. Even if the mechanism is different, it is within the scope of the present invention.

FIG. 1 is a schematic cross-sectional view showing an example of a rubber bearing of the present invention. FIG. 2 shows a rubber composition for bearing of Example 1 [containing dry silica and DEG (diethylene glycol). Is a chart of a vulcanization curve showing the results of measuring the torque when vulcanizing at a vulcanization temperature of 150 ° C. over time using a rheometer. FIG. 3 shows the rubber composition for bearing of Example 2 [containing dry silica and DEG (diethylene glycol). Is a chart of a vulcanization curve showing the results of measuring the torque when vulcanizing at a vulcanization temperature of 150 ° C. over time using a rheometer. FIG. 4 shows a rubber composition for bearing of Example 3 [containing dry silica and DEG (diethylene glycol). Is a chart of a vulcanization curve showing the results of measuring the torque when vulcanizing at a vulcanization temperature of 150 ° C. over time using a rheometer. FIG. 5 is a chart of a vulcanization curve showing the results of measuring the torque over time using a rheometer when the composition of Comparative Example 2 (containing dry silica) was vulcanized at a vulcanization temperature of 150 ° C. It is. FIG. 6 shows the composition of Comparative Example 1 [containing dry silica and DEG (diethylene glycol). Is a chart of a vulcanization curve showing the results of measuring the torque when vulcanizing at a vulcanization temperature of 150 ° C. over time using a rheometer. FIG. 7 shows the composition of Comparative Example 1 [containing humidified silica and DEG (diethylene glycol). And a composition of Comparative Example 2 (containing humidified silica) is a chart of a vulcanization curve showing the results of measuring the torque over time using a rheometer when vulcanized at a vulcanization temperature of 150 ° C. is there.

Explanation of symbols

10 Rubber bearing 11, 12 Flange 13 Soft layer 14 Hard layer 15 Cover layer

Claims (5)

  100 parts by mass of a diene rubber containing 50% by mass or more of natural rubber, 5 to 50 parts by mass of silica, a polyol compound in an amount of 5 to 17% by mass of the silica, a vulcanizing agent, and a vulcanization accelerator. A rubber composition for bearings.   The rubber composition for a support according to claim 1, wherein a content of the silica is 5 to 25 parts by mass with respect to 100 parts by mass of the diene rubber.   The rubber composition for bearing according to claim 1 or 2, wherein the polyol compound is diethylene glycol. The rubber composition for bearings in any one of Claims 1-3 by which the said vulcanization accelerator is represented by following formula (1).

(In the formula, R ¹ and R ² are each independently a chained aliphatic hydrocarbon group having 1 to 6 carbon atoms which may be branched or a cyclic which may be branched having 3 to 6 carbon atoms. Represents an aliphatic hydrocarbon group.)   The rubber bearing which laminated | stacked the rubber layer which consists of the rubber composition for a support in any one of Claims 1-4, and the hard layer alternately.

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