JP5878037B2 - Method for producing rubber compounding agent and rubber composition - Google Patents

Description

  The present invention relates to a method for producing a rubber compounding agent used by blending with a rubber composition, and a rubber composition obtained by compounding the rubber compounding agent.

  Conventionally, in order to increase the elasticity of a rubber composition, there is a method of increasing the amount of sulfur or filler as a reinforcing filler or blending a resin. However, with these methods, it is difficult to satisfy low heat buildup and wear resistance. Low heat generation is a characteristic that hysteresis loss is small, and particularly in a rubber composition for a tire, it is an important characteristic for improving the fuel efficiency by reducing the rolling resistance of the tire. Since high elasticity is in a trade-off relationship, it is required to improve the balance between the two.

  The following Patent Documents 1 and 2 disclose a method in which a part of the filler is replaced with a rubber gel composed of crosslinked diene rubber particles, but this is insufficient in terms of achieving high elasticity.

  Patent Document 3 below discloses a method of blending a rubber gel having a hydroxyl group and an isocyanate silane coupling agent into a rubber composition, and may further blend a filler such as carbon black or silica. Have been described. However, an example in which these fillers are actually blended is not disclosed, and the effect when blending fillers is not disclosed. In this document, the rubber gel and the isocyanate silane coupling agent are separately added to and mixed with the matrix rubber component. Therefore, even if silica is blended, the rubber gel and the silica are passed through the isocyanate silane coupling agent. It is difficult to bond the two firmly, and sufficient elasticity cannot be achieved.

Japanese Patent No. 3299343 Japanese Patent Laid-Open No. 10-204217 JP-T-2004-506058

  The present invention has been made in view of the above points, and a method for producing a rubber compounding agent capable of improving the balance between high elasticity and low heat build-up, and a rubber containing the rubber compounding agent An object is to provide a composition.

  The method for producing a rubber compounding agent according to the present invention comprises a rubber gel comprising crosslinked diene rubber particles and having a hydroxyl group, 30 to 60 parts by mass of silica with respect to 100 parts by mass of the rubber gel, A rubber compounding agent comprising a rubber gel-silica composite is obtained by mixing an isocyanate silane coupling agent in an amount corresponding to 25 to 100 mol% in terms of the molar ratio of isocyanate groups to hydroxyl groups.

In the method for producing a rubber composition according to the present invention, 10 to 50 parts by mass of the rubber compounding agent thus obtained is mixed with 100 parts by mass of a diene rubber as a matrix rubber component. .
The rubber composition according to the present invention comprises a rubber gel comprising crosslinked diene rubber particles and having a hydroxyl group, and 30 to 60 parts by mass of silica based on 100 parts by mass of the rubber gel. A diene rubber 100 as a matrix rubber component containing a rubber compounding agent composed of a rubber gel-silica composite bonded via an isocyanate silane coupling agent in an amount corresponding to 25 to 100 mol% in terms of the molar ratio of isocyanate groups to groups. 10-50 mass parts is mix | blended with respect to a mass part.

  According to the present invention, a rubber gel having a hydroxyl group, silica, and an isocyanate silane coupling agent are mixed in advance at a predetermined ratio, so that the rubber gel and the silica are bonded via the isocyanate silane coupling agent, and the two are combined together. A rubber gel-silica composite is obtained. In this way, the rubber gel and the silica are firmly bonded, and since the rubber gel is originally capable of co-crosslinking with the matrix rubber, the rubber gel-silica composite can be effectively added to the rubber composition. It is considered that the reinforcing property is improved. Therefore, according to the present invention, the balance between high elasticity and low heat build-up can be improved.

It is explanatory drawing which showed typically the state in the rubber composition of the rubber gel-silica composite_body | complex which concerns on embodiment. It is explanatory drawing which showed typically the state in the rubber composition of the rubber gel and silica in normal silica mixing | blending.

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

  The rubber gel-silica composite as a rubber compounding agent (masterbatch) according to the embodiment is obtained by mixing a rubber gel composed of crosslinked diene rubber particles, silica, and an isocyanate silane coupling agent.

  The rubber gel is a particulate rubber composed of a crosslinked body having a diene rubber structure, and can be produced by crosslinking a rubber dispersion. Examples of the rubber dispersion include rubber latex produced by suspension polymerization, rubber dispersion obtained by emulsifying solution-polymerized rubber in water, and examples of the crosslinking agent include organic peroxides and sulfur-based crosslinking. Agents and the like. The rubber particles can also be crosslinked by copolymerization with a polyfunctional compound having a crosslinking action during the emulsion polymerization of the rubber. Specifically, for example, disclosed in JP-A-6-57038, JP-A-10-204225, JP-T 2004-504465, JP-T 2004-506058, JP-T 2004-530760, and the like. The method can be used.

  Examples of the diene rubber constituting the rubber gel include natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, styrene-isoprene rubber, butadiene-isoprene rubber, styrene-isoprene-butadiene copolymer rubber, and nitrile rubber. These may be used alone or in combination of two or more. Preferably, polybutadiene rubber or styrene butadiene rubber is the main component.

  The glass transition temperature (Tg) of the rubber gel is preferably -100 to -10 ° C. By using such a rubber gel having a low glass transition temperature, it is possible to reduce the hysteresis loss and reduce the heat generation. The glass transition temperature is more preferably −100 to −50 ° C. The glass transition temperature of the rubber gel can be adjusted by the type of diene rubber used as a base and the degree of crosslinking thereof. The glass transition temperature is a value (temperature increase rate 20 ° C./min) measured using differential scanning calorimetry (DSC) in accordance with JIS K7121.

The particle size of the rubber gel is preferably an average particle size (DVN value (d ₅₀ ) according to DIN 53 206) of 5 to 2000 nm from the viewpoints of dispersibility, low heat build-up, reinforcement, etc. with respect to the matrix rubber component. Preferably it is 10-500 nm, More preferably, it is 20-200 nm.

  In the present embodiment, modified diene rubber particles having a hydroxyl group are used as the rubber gel. Such a rubber gel having a hydroxyl group may be synthesized using a monomer having a hydroxyl group introduced during polymerization of a diene rubber, or a terminal-modified rubber having a hydroxyl group introduced into the active terminal after polymerization. You can also. Moreover, you may introduce | transduce a hydroxyl group into a polymer terminal by using what generates a hydroxy radical for the initiator at the time of superposition | polymerization. Moreover, after producing diene rubber particles by the above-mentioned crosslinking, a hydroxyl group can be incorporated into the particle surface by reacting a compound having a hydroxyl group with a C═C double bond on the particle surface.

Although it does not specifically limit as said silica, It is preferable to use the wet silica which has a hydrous silicic acid as a main component. BET specific surface area of silica is preferably, more preferably 130~220m ² / g is particularly but not limited to 50 to 250 m ² / g. The BET specific surface area is a nitrogen adsorption specific surface area according to the BET method, and is measured according to the BET method described in ISO 5794. Silica can enhance the reinforcing effect by being integrated with the rubber gel, and can also agglomerate the rubber gel by shearing the silica when mixed with the rubber gel, thereby suppressing the generation of the rubber gel aggregate.

  The isocyanate silane coupling agent is an organosilicon compound having an alkoxyl group as a hydrolyzable group bonded to a silicon atom and an isocyanate group (NCO), and various isocyanate alkoxysilanes can be used. Preferable examples include 3-isocyanatopropyltrialkoxysilane, and particularly preferable are 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropyltrimethoxysilane. In the isocyanate silane coupling agent, the alkoxyl group has reactivity with the silanol group on the surface of the silica particles, and the isocyanate group has reactivity with the hydroxyl group of the rubber gel. Therefore, the rubber gel and silica are firmly bonded via the isocyanate silane coupling agent.

  When the rubber gel, silica, and isocyanate silane coupling agent are mixed to produce a rubber gel-silica composite, the amount of silica can be 30 to 60 parts by mass with respect to 100 parts by mass of the rubber gel. When the amount of silica is less than 30 parts by mass, the rubber gel is not sufficiently refined when mixed with the rubber gel, and the effect of increasing elasticity cannot be obtained. In addition, low heat build-up is impaired. On the other hand, when the amount of silica exceeds 60 parts by mass, the rubber gel-silica composite becomes large and the low heat build-up is impaired. The amount of silica is more preferably 30 to 50 parts by mass, and still more preferably 40 to 50 parts by mass with respect to 100 parts by mass of the rubber gel.

On the other hand, the amount of the isocyanate silane coupling agent is preferably an amount corresponding to 25 to 100 mol% in terms of the molar ratio of isocyanate groups to hydroxyl groups of the rubber gel. If the amount of the isocyanate silane coupling agent is too small, the effect of bonding the rubber gel and silica cannot be obtained sufficiently. Conversely, if the amount is too large, the elongation at break is lowered. The amount of the isocyanate silane coupling agent is more preferably an amount corresponding to 30 to 80 mol% in the above molar ratio. Here, the molar ratio of the isocyanate group of the isocyanate silane coupling agent to the hydroxyl group of the rubber gel is the ratio of the number of moles of isocyanate group when the number of moles of the hydroxyl group is 100. The amount of hydroxyl groups in the rubber gel can be measured by ¹³ C-NMR. For example, in the case of rubber gel A synthesized in the examples described later, the hydroxyl group is about 2.2 mol% by measurement, and 100 g of rubber gel (since the main component of the rubber gel is butadiene, the monomer unit is butadiene monomer (MW54)). , There are 1.85 mol of butadiene monomer in 100 g of rubber gel). When the hydroxyl group and the isocyanate group are equimolar amounts, it becomes 100 mol%.

  The mixing method is not particularly limited, and for example, the above three components may be mixed by applying mechanical shearing force with a mixer such as a Banbury mixer, a single-screw kneader, or a twin-screw kneader. As a result, in the isocyanate silane coupling agent, the alkoxyl group is bonded to the silanol group on the surface of the silica particles, and the isocyanate group reacts with the hydroxyl group of the rubber gel, so that the rubber gel and silica are firmly bonded via the isocyanate silane coupling agent. A bonded rubber gel-silica composite is obtained. In addition, since the rubber gel can be agglomerated by shearing the silica during mixing, the rubber compounding agent having good dispersibility with respect to the matrix rubber component can be obtained by suppressing the generation of the rubber gel agglomerate.

  The rubber composition according to the embodiment is obtained by mixing the rubber gel-silica composite with a diene rubber as a rubber compounding agent and dispersing the diene rubber as a continuous phase, that is, a matrix rubber component. A rubber gel-silica composite as a phase is dispersed. Specifically, in the rubber composition of the embodiment, as shown in FIG. 1, it is considered that the rubber gel and the silica are firmly bonded, and the rubber gel and the matrix rubber are bonded by sulfur crosslinking. As described above, since the rubber gel having a smaller hysteresis loss than the matrix rubber can be selectively bonded to the silica, it is possible to suppress the deterioration of the hysteresis loss and to increase the elasticity by the reinforcing action of the silica bonded to the rubber gel. It is thought that it can plan. On the other hand, when rubber gel and silica are dry mixed as in the prior art, it is considered that there are many physical bonds between the matrix rubber and silica, as shown in FIG. As a result, the hysteresis loss becomes large, and the effect of increasing elasticity due to the composite integration of rubber gel and silica cannot be obtained. Therefore, according to the present embodiment, compared with the case where the composite is not prepared in advance, the heat generation is reduced by the hysteresis loss and the direction is advantageous for higher elasticity. Therefore, the balance between higher elasticity and lower heat generation is achieved. Can be improved as compared with the prior art.

  As the diene rubber as the matrix rubber component, a raw rubber that has not been crosslinked is used. Naturally, the rubber gel that is a crosslinked diene rubber particle is included in the diene rubber as the matrix rubber component. I can't. Examples of the diene rubber include natural rubber (NR), polyisoprene rubber (IR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), styrene-isoprene rubber, butadiene-isoprene rubber, styrene-isoprene- Examples thereof include butadiene copolymer rubber, nitrile rubber (NBR), and butyl rubber (IIR). These may be used alone or in combination of two or more. Among these, when used for tires, a blend of one or more of natural rubber, polyisoprene rubber, styrene-butadiene rubber, and polybutadiene rubber is preferable.

  The blending amount of the rubber gel-silica composite in the rubber composition is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the diene rubber as the matrix rubber component. When the blending amount of the rubber gel-silica composite is too small, the effect of improving the elastic modulus becomes insufficient. Conversely, when the blending amount is too large, the elongation at break is lowered.

  The rubber composition according to this embodiment preferably contains a reinforcing filler (inorganic filler) such as silica or carbon black. These reinforcing fillers are considered to exhibit an effect of dispersing the rubber gel-silica composite by shearing when kneaded with the matrix rubber component. Therefore, by blending the reinforcing filler, it is possible to easily exhibit the effect of improving the elastic modulus by the rubber gel-silica composite, and it is possible to suppress the decrease in elongation at break. The compounding amount of the reinforcing filler is preferably 30 to 150 parts by mass, more preferably 30 to 100 parts by mass, and still more preferably 40 with respect to 100 parts by mass of the diene rubber as the matrix rubber component. -70 mass parts. The amount of the reinforcing filler mentioned here does not include the amount of silica contained in the rubber gel-silica composite.

As the silica as the reinforcing filler, it is preferable to use wet silica containing hydrous silicic acid as a main component, similarly to the silica used in the rubber gel-silica composite, and the BET specific surface area of silica is particularly preferably but not limited to a 50 to 250 m ² / g, more preferably 130~220m ² / g. In addition, when compounding silica as a reinforcing filler, it is preferable to use a sulfur-containing silane coupling agent such as sulfide silane or mercaptosilane in combination, and the sulfur-containing silane coupling agent is usually used as the reinforcing filler. It can be used at 2 to 25 parts by mass with respect to 100 parts by mass of silica.

  Further, the carbon black as the reinforcing filler is not particularly limited. For example, SAF class (N100 series), ISAF class (N200 series), HAF class (N300 series), FEF (N500 series), GPF ( N600 series) (both ASTM grade). These reinforcing fillers such as carbon black and silica may be used alone or in combination of two or more.

  In addition to the above components, the rubber composition according to this embodiment is generally used in rubber compositions such as softeners, plasticizers, anti-aging agents, zinc white, stearic acid, vulcanizing agents, and vulcanization accelerators. Various additives to be added can be arbitrarily blended. In producing the rubber composition, the rubber gel-silica composite, the reinforcing filler, and these additives may be added to the diene rubber as the matrix rubber component and mixed (kneaded). Usually, in the first mixing stage, chemicals excluding vulcanizing additives such as vulcanizing agents and vulcanization accelerators are added to diene rubber as a matrix rubber component together with rubber gel-silica composite and reinforcing filler. By adding and kneading, a rubber composition can be produced by adding and mixing the vulcanizing additive to the kneaded product obtained in the first mixing stage in the subsequent second mixing stage. For mixing, a Banbury mixer, an open roll, a single-screw kneader, a twin-screw kneader or the like generally used in the preparation of the rubber composition can be used.

  Examples of the vulcanizing agent include sulfur and sulfur-containing compounds, and are not particularly limited. However, the blending amount is 0.1 to 10 parts by mass with respect to 100 parts by mass of the diene rubber as the matrix rubber. It is preferable that it is 0.5-5 mass parts. Moreover, as a compounding quantity of a vulcanization accelerator, it is preferable that it is 0.1-7 mass parts with respect to 100 mass parts of this diene rubber, More preferably, it is 0.5-5 mass parts.

  The rubber composition thus obtained is vulcanized and molded according to a conventional method, for example, tires such as treads and sidewalls, belts and ply topping rubbers, bead fillers, rim strips, conveyor belts, and vibration-proof rubbers. It can be used for various applications such as. Preferably, since the rubber composition can achieve high elasticity while suppressing deterioration of low heat build-up, it is used as a rubber member for a pneumatic tire. The balance of sex can be improved.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Synthesis of rubber gel A]
The rubber gel was synthesized by synthesizing a butadiene latex and then adding an organic peroxide for crosslinking. Specifically, in a reaction vessel, 252 g of distilled water, 6.6 g of potassium rosinate (“Longis K25” manufactured by Arakawa Chemical Industries, Ltd.), and Naphthalenesulfonic acid formalin condensate Na salt (“Demol N” manufactured by Kao Corporation) ) 0.14 g, 0.70 g of potassium chloride, 0.14 g of tetraethylenepentamine and 0.34 g of dodecanethiol were added, and after bubbling with nitrogen, the reaction vessel was kept at 0 ° C. to vaporize 100.8 g of liquefied butadiene. The mixture was transferred to a reaction vessel by the method and emulsified. Thereafter, 0.28 g of cumene hydroxyperoxide and 0.41 g of 30% by mass hydrogen peroxide were added to initiate polymerization, and the reaction was carried out for 24 hours to obtain a butadiene latex.

After adding distilled water so that the rubber gel concentration of the synthesized butadiene latex is 20% by mass, 200 g of butadiene latex (20% by mass) is added to t-butyl peroxylaurate (“Perbutyl L” manufactured by NOF Corporation). 3.6 g was added, the temperature of the reaction vessel was 40 ° C., stirring was performed at 30 rpm, and nitrogen bubbling was gently performed. After 2 hours, the set temperature was gradually increased to 90 ° C. over about 1 hour. During the gelation reaction, the stirring speed was 5 rpm and nitrogen bubbling was stopped. After the reaction for 4 hours, the sample was returned to room temperature and ethanol was poured to precipitate a sample (rubber gel). Thereafter, the sample was washed and vacuum-dried to obtain a hydroxy-modified rubber gel A (polybutadiene gel) having Tg = −80 ° C. and an average particle size = 130 nm. The obtained rubber gel A had 2.2 mol% of hydroxyl groups. The amount of hydroxyl group introduced was confirmed by ¹³ C-NMR measurement (solid NMR) of the rubber gel and comparing the peak around 60 ppm with the peak around 130 ppm.

[Synthesis of rubber gel B]
Similar to rubber gel A, rubber gel B was synthesized by peroxide crosslinking of latex. Specifically, in a reaction vessel, 315 g of distilled water, 8.3 g of potassium rosinate (“Longis K25” manufactured by Arakawa Chemical Co., Ltd.), Na-naphthalenesulfonic acid formalin condensate Na salt (“Demol N” manufactured by Kao Corporation) ) Add 0.18g, 0.88g of potassium chloride, 0.18g of tetraethylenepentamine and 0.43g of dodecanethiol, and after bubbling with nitrogen, keep the reaction vessel at 0 ° C and transfer 50.3g of styrene first. A styrene emulsion was obtained. Thereafter, 100.8 g of liquefied butadiene was transferred to the reaction vessel by a vaporization method and emulsified. Thereafter, 0.35 g of cumene hydroxyperoxide and 0.51 g of 30% by mass hydrogen peroxide were added to initiate polymerization, and the reaction was carried out for 24 hours to obtain a styrene butadiene latex.

After adding distilled water so that the rubber gel concentration of the synthesized styrene butadiene latex is 20% by mass, 200 g of styrene butadiene latex (20% by mass) is added to t-butyl peroxylaurate (“Perbutyl L” manufactured by NOF Corporation). )) 3.6 g was added, the temperature of the reaction vessel was brought to 40 ° C., stirring at 30 rpm, and gentle bubbling of nitrogen was performed. After 2 hours, the set temperature was gradually increased to 90 ° C. over about 1 hour. During the gelation reaction, the stirring speed was 5 rpm and nitrogen bubbling was stopped. After the reaction for 4 hours, the sample was returned to room temperature and ethanol was poured to precipitate a sample (rubber gel). Thereafter, the sample was washed and vacuum-dried to obtain a hydroxy-modified rubber gel B (styrene polybutadiene gel) having Tg = −15 ° C. and an average particle size = 60 nm. The obtained rubber gel B had 3.0 mol% of hydroxyl groups. The amount of hydroxyl group introduced was determined by ¹³ C-NMR measurement (solid NMR) of the rubber gel and comparing peaks near 60 ppm with peaks at 130 ppm and 140 ppm.

[Production of rubber gel-silica composite]
Using a Banbury mixer, the rubber gels A and B obtained above were mixed with silica and an isocyanate silane coupling agent according to the composition (parts by mass) shown in Table 1 below, and the rubber gel-silica composite according to the example was mixed. 2, 3, 7, 8, 10 and rubber gel-silica composites 1, 4, 5, 6, 9 according to comparative examples were prepared. Specifically, the mixing was performed at an initial temperature of 100 ° C. for 10 seconds with rubber gel mastication, 20 seconds with silica, and 90 seconds with isocyanate silane coupling agent. When the reaction rate of the isocyanate silane coupling agent was confirmed by NMR for each of the obtained composites 1 to 10, the isocyanate groups reacted 100% in any composite. The reaction rate is calculated by the integration ratio of the signal that changes to C (—NHCO—) of the urethane bond by the reaction of C (—NCO) of the isocyanate group of the isocyanate silane coupling agent in ¹³ C-NMR. did.

  Details of each component in Table 1 are as follows.

Silica: “Ultrasil VN3” manufactured by Degussa, BET specific surface area = 168 m ² / g
・ Isocyanate silane coupling agent: 3-isocyanatopropyltriethoxysilane, “KBE-9007” manufactured by Shin-Etsu Chemical Co., Ltd.

[First embodiment]
Using a Banbury mixer, a rubber composition was prepared according to the formulation (parts by mass) shown in Table 2 below. Specifically, in the first mixing stage, components other than sulfur and vulcanization accelerator are added and mixed, and then the resulting mixture is added and mixed with sulfur and vulcanization accelerator in the final mixing stage to obtain a rubber composition. A product was prepared. Each component in the table is as follows. The composites 1 to 10 in the table are the rubber gel-silica composites obtained above, and the rubber gel A, silica, and isocyanate silane coupling agent in the table are used for the synthesis of these composites. It is the same as each raw material.

IR: Polyisoprene rubber, “IR2200” manufactured by JSR Corporation
Carbon black: “Seast 3” manufactured by Tokai Carbon Co., Ltd., HAF
・ Sulphide silane coupling agent: “Si75” manufactured by Degussa
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Zinc flower: “Zinc flower 3” manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Sulfur: “Sulfur Powder” manufactured by Tsurumi Chemical Co., Ltd.
・ Vulcanization accelerator CZ: “Soxinol CZ” manufactured by Sumitomo Chemical Co., Ltd.
・ Vulcanization accelerator D: “Noxeller D” manufactured by Ouchi Shinsei Chemical Co., Ltd.

Each rubber composition obtained was vulcanized at 160 ° C. for 20 minutes to prepare a test piece having a predetermined shape. Using the obtained test piece, the complex elastic modulus E ^* , the loss coefficient tan δ, and the fracture The time elongation EB was measured. The measuring method is as follows.

E ^* : An index based on JIS K6394, in which the complex elastic modulus E ^* is measured under the conditions of a temperature of 25 ° C., a frequency of 10 Hz, a dynamic strain of 5%, and a static strain of 10%. displayed. The larger the index is, the higher the complex elastic modulus is, and the higher the elasticity is.

Tan δ: According to JIS K6394, the loss factor tan δ was measured under the conditions of a temperature of 25 ° C., a frequency of 10 Hz, a dynamic strain of 5%, and a static strain of 10%, and displayed as an index with the value of Comparative Example 1 as 100. The smaller the index, the smaller the tan δ, and hence the smaller the hysteresis loss and the better the low heat buildup (low fuel consumption).

-EB: The elongation at break was measured by a tensile test according to JIS K6251 (dumbbell shape No. 3), and displayed as an index with the value of Comparative Example 1 being 100. The larger the index, the greater the elongation at break, which is preferable.

  The results are as shown in Table 2, and in Examples 1 to 4 and 8 in which the rubber gel-silica composites according to the examples were blended, low exothermicity was maintained as compared with Comparative Example 1 which was the standard blend. While improving, high elasticity was achieved, and the balance between low heat generation and high elasticity was improved. On the other hand, in Comparative Example 2 in which the rubber gel and the isocyanate silane coupling agent were separately added without complexing, the balance between low exothermic property and high elasticity was improved, but the master batch was prepared with the same composition as Example 1 Is not enough.

  In Comparative Example 3, the rubber gel and the isocyanate silane coupling agent were used as a master batch, and silica was not combined, so the rubber gel aggregated and the low heat build-up was impaired. In Comparative Example 4, since the amount of silica in the composite was small, the effect of increasing elasticity could not be obtained. In Comparative Example 5, on the contrary, the amount of silica in the composite was too large, and thus the low heat build-up was impaired.

  In Comparative Example 6, the isocyanate silane coupling agent added to the composite was too small, and the effect of improving the balance between low heat buildup and high elasticity could not be obtained. In Comparative Example 7, on the contrary, there was too much isocyanate silane coupling agent, and the elongation at break was greatly reduced.

  As is clear from the results of Examples 1 and 5 and Comparative Examples 8 and 9, if the amount of the composite is small, a sufficient elasticity increase effect cannot be obtained, and conversely if too large, the elongation at break decreases. End up.

  In Examples 6 and 7, since the blending amount of the reinforcing filler was smaller than that of Comparative Example 1, the elastic modulus was the same or slightly inferior, but the low heat build-up was remarkably improved. It was improved in terms of the balance between the two performances. From the results of Examples 6 and 7, when the compounding amount of the reinforcing filler is small, the effect of improving the elastic modulus is small. In Examples 6 and 7, a remarkable effect of increasing elasticity was recognized with respect to Comparative Example 10 in which the compounding amount of the reinforcing filler was the same.

  As is clear from the results of Example 8, the balance between low heat build-up and high elasticity was improved even if the type of rubber gel constituting the composite was changed. In Example 8, the glass transition temperature of the base rubber gel was higher than that in Example 1, and thus the effect of improving the heat generation was reduced, but the effect of increasing the elasticity was higher. It was.

[Second Embodiment]
Using a Banbury mixer, a rubber composition was prepared in the same manner as in the first example according to the formulation (parts by mass) shown in Table 3 below. About each component in a table | surface, it is as follows and others are the same as 1st Example.

SBR: Styrene butadiene rubber, “SBR1502” manufactured by JSR Corporation
・ BR: Polybutadiene rubber, “BR01” manufactured by JSR Corporation

About each obtained rubber composition, after producing a test piece similarly to 1st Example, complex elastic modulus E ^* , loss coefficient tan-delta, and elongation at break EB were measured. The measuring method is as described above, but here, it is expressed as an index with the value of Comparative Example 11 being 100.

  The results are as shown in Table 3. Like the first example, even when the type of diene rubber used as the matrix rubber component is changed, the elongation at break is greatly deteriorated by blending the rubber gel-silica composite. Thus, an excellent effect was obtained in that the elasticity was increased and the low heat generation was improved.

  The rubber composition according to the present invention can be used for various rubber products such as tires, anti-vibration rubbers, and belts, and can be preferably used for rubber members that constitute pneumatic tires.

Claims (6)

  A rubber gel composed of crosslinked diene rubber particles and having hydroxyl groups, 30 to 60 parts by weight of silica with respect to 100 parts by weight of the rubber gel, and 25 to 100 moles in terms of a molar ratio of isocyanate groups to hydroxyl groups of the rubber gel %, A rubber compounding agent comprising a rubber gel-silica composite is obtained by mixing an amount of an isocyanate silane coupling agent corresponding to%.   The rubber rubber compounding method according to claim 1, wherein the rubber gel has an average particle size of 5 to 2000 nm and a glass transition temperature of -100 to -10 ° C. A method for producing a rubber composition , comprising mixing 10 to 50 parts by mass of the rubber compounding agent obtained by the method according to claim 1 or 2 with respect to 100 parts by mass of a diene rubber as a matrix rubber component. Furthermore, the manufacturing method of the rubber composition of Claim 3 which mixes 30-150 mass parts of reinforcing fillers with respect to 100 mass parts of said diene rubbers. A rubber gel composed of crosslinked diene rubber particles and having a hydroxyl group, and 30 to 60 parts by mass of silica with respect to 100 parts by mass of the rubber gel is 25 to 100 in terms of a molar ratio of isocyanate groups to hydroxyl groups of the rubber gel. 10 to 50 parts by mass of a rubber compounding agent comprising a rubber gel-silica composite bonded through an isocyanate silane coupling agent in an amount corresponding to mol% with respect to 100 parts by mass of a diene rubber as a matrix rubber component. A rubber composition obtained by blending. The rubber composition according to claim 5, further comprising a reinforcing filler in an amount of 30 to 150 parts by mass with respect to 100 parts by mass of the diene rubber.