WO2012073822A1

WO2012073822A1 - Resin coated silica, rubber composition and tire

Info

Publication number: WO2012073822A1
Application number: PCT/JP2011/077185
Authority: WO
Inventors: 正幸齋藤; 大久保　明浩; 裕昭斎藤; 山崎　倫康; 優紀八木
Original assignee: 群栄化学工業株式会社
Priority date: 2010-12-01
Filing date: 2011-11-25
Publication date: 2012-06-07
Also published as: JP2012116972A; JP5731805B2; TW201235392A

Abstract

The present invention relates to resin coated silica which is obtained by coating silica that has a nitrogen adsorption specific surface area as determined by a BET method of 50-300 m²/g sequentially with a first coating material and a second coating material. The resin coated silica is characterized in that the first coating material contains a phenol, and the second coating material contains (A) a novolac type phenolic resin and a curing agent and/or (B) a resol type phenolic resin. The present invention is capable of providing: resin coated silica which has good kneadability with a rubber and excellent hardness imparting effect; and a rubber composition and a tire, each of which enables a good balance between steering stability and improvement in the fuel efficiency of a vehicle due to decrease in the rolling resistance of tires.

Description

Resin-coated silica, rubber composition and tire

The present invention relates to a resin-coated silica, a rubber composition containing the resin-coated silica, and a tire using the rubber composition.
This application claims priority based on Japanese Patent Application No. 2010-268709 filed in Japan on December 1, 2010, the contents of which are incorporated herein by reference.

In recent years, with increasing international interest in the global environment, there is an increasing demand for lower fuel consumption in automobiles from the viewpoint of reducing carbon dioxide emissions.
The rolling resistance of the tire tread portion has a great influence on the fuel consumption of an automobile. Therefore, in order to satisfy both environmental performance and safety, it is necessary to achieve both improvement in automobile fuel efficiency and steering stability due to a decrease in rolling resistance of the tire tread portion.

A rubber composition in which carbon black is blended with rubber is used for the tire tread portion in order to impart wear resistance and reinforcement. On the other hand, by using silica instead of carbon black, in addition to providing wear resistance and reinforcement, the balance between improved fuel economy and handling stability due to reduced rolling resistance of tires can be improved. Therefore, rubber compositions containing silica have been used (see Non-Patent Document 1).
However, since the surface of the silica particles is covered with silanol groups, the silica particles tend to aggregate in the rubber and have poor dispersibility. As a result, there is a problem that silica particles and rubber are difficult to mix. In addition, it was difficult to obtain an effect of imparting hardness to the tire.

In order to improve the dispersibility of the silica particles in the rubber, a method of surface-treating silica with a silane coupling agent containing a polysulfide structure has been disclosed (see Patent Document 1).
Also disclosed are resin-coated silica in which silica is coated with a phenol resin obtained by reacting phenols and aldehydes in the presence of a catalyst, and a rubber composition containing rubber as an essential component (Patent Document 2). reference).

Japanese Patent Laid-Open No. 08-333481 JP 2010-089443 A

However, in the methods described in Patent Documents 1 and 2, the dispersibility of silica particles in rubber is poor, and it is insufficient to achieve both improvement in vehicle fuel efficiency and steering stability due to a decrease in tire rolling resistance. is there. In addition, the kneadability between silica and rubber is not sufficient, and the effect of imparting hardness to the tire is insufficient.
The present invention has been made in view of the above circumstances, and is compatible with resin-coated silica having good kneadability with rubber and excellent hardness-imparting effect, and improved fuel efficiency and steering stability due to reduced rolling resistance. It is an object to provide a rubber composition and a tire.

In order to solve the above problems, the present invention employs the following configuration.
That is, the resin-coated silica of the present invention is a resin-coated silica in which silica having a nitrogen adsorption specific surface area of 50 to 300 m ² / g according to the BET method is sequentially coated with a first coating material and a second coating material, The first coating material contains phenols, and the second coating material contains (A) at least one of a novolac type phenol resin and a curing agent, and (B) a resol type phenol resin.
In the resin-coated silica of the present invention, the first coating material preferably contains a curing agent.
In the resin-coated silica of the present invention, the first coating material preferably contains a silane coupling agent.
The rubber composition of the present invention contains the resin-coated silica of the present invention and rubber.
The tire of the present invention is characterized in that the rubber composition of the present invention is used for a tire tread portion.

According to the present invention, it is possible to provide a resin-coated silica having good kneadability with rubber and excellent hardness imparting effect.
In addition, according to the present invention, it is possible to provide a rubber composition and a tire that achieve both improvement in fuel efficiency and steering stability of a vehicle due to a decrease in rolling resistance of the tire.

<Resin-coated silica>
The resin-coated silica of the present invention is obtained by sequentially coating silica having a nitrogen adsorption specific surface area of 50 to 300 m ² / g by BET method with a first coating material and a second coating material.

(silica)
The silica used for the resin-coated silica of the present invention may be wet silica or dry silica. Of these, wet silica is preferred because of its higher reinforcing effect.
In the present invention, “nitrogen adsorption specific surface area by BET method” means that nitrogen gas is adsorbed on the surface of powder particles, and the amount of monomolecular adsorption is measured by the BET equation from the relationship between the pressure and the amount of adsorption at that time. The specific surface area required.
The nitrogen adsorption specific surface area of silica by the BET method is 50 to 300 m ² / g, preferably 90 to 230 m ² / g, and more preferably 115 to 215 m ² / g.
When the nitrogen adsorption specific surface area of silica is not less than the lower limit, the reinforcing effect on rubber is excellent.
On the other hand, when it is at most the upper limit value, the silica dispersibility in the rubber is excellent.
Silica may be used alone or in combination of two or more.

(First coating material)
The first coating material contains phenols.
In the present invention, “phenols” refers to an aromatic hydroxy compound in which a hydrogen atom of an aromatic hydrocarbon nucleus is substituted with a hydroxy group.
Phenols include phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, allylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol, urushiol, etc. Is mentioned.
Among these, cresol, allylphenol, cardanol, and cashew nut shell oil are preferable, and cresol and cardanol are more preferable because they are liquid and are easy to coat silica and are economically advantageous.
Among the cresols, ortho-cresol is preferable. Of allylphenols, orthoallylphenol is preferred.
Phenols may be used alone or in combination of two or more.

The content of phenols in the first coating material (excluding the solvent and the dispersion medium) is 40% by mass or more and less than 100% by mass with respect to 100% by mass of the first coating material (excluding the solvent and the dispersion medium). Preferably, 60 mass% or more and less than 100 mass% is more preferable, and 100 mass% may be sufficient.
It becomes easy to reduce the polarity of the silica surface as content of phenols is more than a desirable lower limit. In addition, the silica coated with the first coating material can be easily coated with the second coating material.

The first coating material may contain components other than phenols.
In the resin-coated silica of the present invention, the first coating material preferably contains a curing agent. When the rubber composition containing the resin-coated silica is vulcanized by the combined use of the curing agent, the first coating material undergoes a curing reaction together with the second coating material, and the first coating material and the second coating material And the effect of integrating them is further increased.
In the present invention, the “curing agent” refers to a compound that crosslinks by reacting with a hydrogen atom of a phenolic aromatic hydrocarbon nucleus or a phenolic hydroxyl group.
Examples of the curing agent include hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4′-diaminodiphenylmethane, acetaldehyde ammonia, a resol type phenol resin, a urethane resin, and an epoxy resin. Among these, hexamethylenetetramine, hexamethoxymethylmelamine, and 4,4′-diaminodiphenylmethane are preferable, and hexamethylenetetramine is particularly preferable because the curing reaction easily proceeds well. A hardening | curing agent may be used individually by 1 type, and may use 2 or more types together.

The content of the curing agent in the first coating material (excluding the solvent and the dispersion medium) is preferably 0.5 to 50 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the phenols.
When the content of the curing agent is not less than the preferred lower limit, the effect of integrating the first coating material and the second coating material is improved, and when the obtained rubber composition is used as a tire, a good hardness is obtained. The steering stability is improved. On the other hand, even if the preferable upper limit is exceeded, the hardness imparting effect and the steering stability are not improved according to the increase. If it is less than or equal to the preferable upper limit value, the cost can be reduced.

In the resin-coated silica of the present invention, the first coating material preferably contains a silane coupling agent. The combined use of the silane coupling agent increases the affinity between silica and phenols, and increases the adhesion between silica and the first coating material.
Examples of silane coupling agents include aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, and 2- (3,4-epoxycyclohexyl) ) Epoxy silane such as ethyltrimethoxysilane; Vinyl silane such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxysilane such as 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; p- Styrylsilane such as styryltrimethoxysilane; mercaptosilane such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; bis (triethoxysilylpropyl) tetras Such as Surufidoshiran such as Fido, and the like.
Among these, 3-aminopropyltriethoxysilane is particularly preferable because adhesion between silica and the first coating material is further improved.
A silane coupling agent may be used individually by 1 type, and may use 2 or more types together.

In addition, the silane coupling agent containing the polysulfide structure (sulfur atom) described in Patent Document 1 is expensive, and there is a problem in that it is expensive to obtain a tire. However, in the resin-coated silica of the present invention, a silane coupling agent is not essential. Even when a silane coupling agent is used, instead of using this silane coupling agent containing a sulfur atom, the adhesion between silica and the first coating material can be achieved by using the above-mentioned general silane coupling agent. The effect of improving the performance can be obtained, and the cost can be reduced. The content of the silane coupling agent in the first coating material (excluding the solvent and the dispersion medium) is preferably 5 to 700 parts by mass, more preferably 30 to 350 parts by mass with respect to 100 parts by mass of the phenols.
When the content of the silane coupling agent is equal to or more than the preferred lower limit, the affinity between silica and phenols increases, and the adhesion between silica and the first coating material increases. When the content of the silane coupling agent is not more than the preferable upper limit value, strength as a rubber product such as breaking strength is not lowered.

(Second coating material)
The second coating material contains at least one of (A) a novolac type phenol resin and a curing agent, and (B) a resol type phenol resin. That is, the second coating material is either (A) a novolak type phenol resin and a curing agent, and (B) a resol type phenol resin, or (A) a novolac type phenol resin, a curing agent, and (B) a resole. Both types of phenolic resins are included.

(A) Novolak-type phenolic resin and curing agent As the novolac-type phenolic resin, those obtained by reacting phenols and aldehydes in the presence of an acid catalyst are used. Moreover, the novolak-type phenol resin which modified | denatured the reaction material of phenols and aldehydes with cashew nut shell oil, tung oil, rosin etc. in presence of an acid catalyst can also be used.
In the present invention, “aldehydes” refers to compounds having at least one hydrogen atom in the carbonyl group, that is, having a formyl group —CHO.
Phenols may be phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol, urushiol, etc. it can. The said phenols may be used individually by 1 type, and may use 2 or more types together.
As aldehydes, formaldehyde, paraformaldehyde, trioxane, glyoxal, benzaldehyde, salicylaldehyde, and the like can be used. The aldehydes may be used alone or in combination of two or more.
Among them, since it is easier to achieve both reduction in rolling resistance of the tire and driving stability of the vehicle when the tire is used, phenols are preferably phenol, cresol, cardanol, butylphenol, octylphenol, and bisphenol A, phenol, And cardanol is more preferred. As aldehydes, formaldehyde and paraformaldehyde are preferable, and formaldehyde is more preferable.
Examples of the acid catalyst include hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, succinic acid, butyric acid, lactic acid, benzenesulfonic acid, p-toluenesulfonic acid, boric acid, or a salt with a metal such as zinc chloride or zinc acetate. The said acid catalyst may be used individually by 1 type, and may use 2 or more types together.
A novolak-type phenol resin may be used individually by 1 type, and may use 2 or more types together.

When the second coating material contains (A) a novolak type phenol resin and a curing agent, and (B) does not contain a resol type phenol resin, the novolak type phenol resin in the second coating material (excluding the solvent and the dispersion medium) The content of is preferably 30 to 99% by mass, more preferably 60 to 98% by mass, and still more preferably 70 to 95% by mass with respect to 100% by mass of the second coating material (excluding the solvent and dispersion medium).
When the content of the novolac type phenol resin is equal to or more than the preferable lower limit value, the kneadability of silica with rubber is improved. In addition, when tires are used, it is easy to achieve both a reduction in tire rolling resistance and driving stability of automobiles. When the content of the novolac type phenol resin is not more than the preferable upper limit value, physical properties as a rubber product such as breaking strength and hardness are not deteriorated.

(A) As a hardening | curing agent in a component, the thing similar to the hardening | curing agent in the said 1st coating material is mentioned. Among these, hexamethylenetetramine, hexamethoxymethylmelamine, and 4,4′-diaminodiphenylmethane are more preferable, and hexamethylenetetramine is particularly preferable because the curing reaction easily proceeds well.
A hardening | curing agent may be used individually by 1 type, and may use 2 or more types together.

The content of the curing agent in the second coating material is preferably 1 to 30 parts by mass and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the novolac type phenol resin.
When the content of the curing agent is equal to or more than the preferred lower limit, the effect of imparting hardness to the vulcanized rubber composition is improved. In addition, when a tire is used, it is easy to achieve both reduction in rolling resistance and driving stability of the automobile. On the other hand, even if the preferable upper limit is exceeded, the tire hardness imparting effect corresponding to the increase and the improvement of the driving stability of the automobile are not observed. If it is less than or equal to the preferable upper limit value, the cost can be reduced.

(B) Resol type phenol resin As the resol type phenol resin, a product obtained by reacting phenols and aldehydes in the presence of an alkali catalyst is used. In addition, a resol type phenol resin obtained by modifying a reaction product of a phenol and an aldehyde with cashew nut shell oil, tung oil, rosin or the like in the presence of an alkali catalyst can also be used. These resol type phenol resins are self-hardening.
Examples of the phenols and aldehydes include the same phenols and aldehydes as those described above for the novolak type phenol resin.
Among them, phenol, cresol, cardanol, butylphenol, and octylphenol are preferred as phenols because phenol tires are more likely to have a reduction in rolling resistance and driving stability of the vehicle when used as a tire, and phenol and cardanol are preferred. More preferred. As aldehydes, formaldehyde and paraformaldehyde are preferable, and formaldehyde is more preferable.
Alkali catalysts include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; ammonium hydroxide; diethylamine, triethylamine, and triethanol. Examples include amines such as amines, ethylenediamine, and hexamethylenetetramine. The said alkali catalyst may be used individually by 1 type, and may use 2 or more types together.
A resol type phenol resin may be used individually by 1 type, and may use 2 or more types together.

When the second coating material contains (B) a resol type phenol resin and (A) a novolac type phenol resin and a curing agent, the resol type phenol resin in the second coating material (excluding the solvent and dispersion medium) The content of is preferably 30 to 100% by mass, more preferably 70 to 100% by mass, and may be 100% by mass with respect to 100% by mass of the second coating material (excluding the solvent and dispersion medium).
When the content of the resol type phenolic resin is equal to or more than the preferable lower limit value, the kneadability of silica with rubber is improved. In addition, when tires are used, it is easy to achieve both a reduction in tire rolling resistance and driving stability of automobiles.

The second coating material includes (A) novolac type phenol resin and curing agent, (B) resol type phenol resin, melamine resin, urea resin, epoxy resin, urethane resin, alkyd resin, unsaturated polyester resin, Polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, ABS resin (acrylonitrile-butadiene-styrene copolymer), AS resin (acrylonitrile-styrene copolymer), acrylic resin, polyamide resin, polycarbonate resin, polyethylene terephthalate resin (C) resins such as polybutylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, and polyether sulfone resin may be used.
Moreover, in order to accelerate | stimulate the hardening reaction of a novolak-type phenol resin and a hardening | curing agent and the hardening reaction of a resol type phenol resin, you may use hardening catalysts, such as a calcium hydroxide, for the 2nd coating material.
(C) When resin is used in combination, (total content of novolac-type phenol resin and resol-type phenol resin) / (content of all resins) in the second coating material (excluding solvent and dispersion medium) Is preferably 0.50 to 1 and more preferably 0.65 to 1 in terms of mass ratio.
When the mass ratio is not less than the preferred lower limit, the kneading property of silica to rubber is improved without deteriorating physical properties as a rubber product such as breaking strength and hardness. In addition, when tires are used, it is easy to achieve both a reduction in tire rolling resistance and driving stability of automobiles.

(Production of resin-coated silica)
The resin-coated silica of the present invention can be produced by sequentially coating the silica with a first coating material and a second coating material. Specifically, there is a method in which silica and a first coating material are mixed, and then a second coating material is added and mixed.

The coating amount of the first coating material is preferably such that the phenols contained in the coating material coated on silica are 0.5 to 50 parts by mass with respect to 100 parts by mass of silica. The amount to be part is more preferable. The larger the specific surface area of silica, the greater the amount of the first coating material applied.
When the phenols contained in the coating material have a preferable lower limit value or more, the polarity of the silica surface is easily reduced. In addition, when the polarity of the silica surface is reduced, the silica coated with the first coating material can be easily coated with the second coating material. On the other hand, when it is not more than the preferred upper limit value, it is easy to achieve both reduction in rolling resistance of the tire and steering stability of the vehicle when the tire is used.

When the first coating material contains a silane coupling agent, the coating amount of the first coating material is 0 for the silane coupling agent contained in the coating material applied to silica to 100 parts by mass of silica. The amount is preferably 3 to 20 parts by mass, and more preferably 1 to 10 parts by mass.
When the silane coupling agent contained in the coating material has a preferable lower limit value or more, the adhesion between the silica and the first coating material tends to increase. On the other hand, even if it exceeds the preferable upper limit value, no improvement in the adhesion between the silica and the first coating material according to the increase is observed. If it is less than or equal to the preferable upper limit value, the cost can be reduced.

When the second coating material contains (A) a novolac type phenolic resin and a curing agent, and (B) does not contain a resol type phenolic resin, the coating amount of the second coating material is the same as that in the coating material applied to silica. The novolac type phenolic resin contained in is preferably in an amount of 0.5 to 50 parts by mass, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of silica.
When the novolac type phenol resin contained in the coating material is equal to or more than the preferable lower limit value, the kneadability of silica to rubber is improved. When the novolac type phenolic resin contained in the coating material has a preferable upper limit value or less, physical properties as a rubber product such as breaking strength and hardness are not deteriorated. When the amount of the novolac-type phenolic resin is within the above-mentioned preferable range, when the tire is used, it is easy to achieve both a reduction in rolling resistance of the tire and a driving stability of the automobile.

When the second coating material contains (B) a resol type phenol resin and (A) a novolac type phenol resin and a curing agent, the coating amount of the second coating material is within the coating material applied to silica. The amount of the resol type phenolic resin contained in is preferably 0.5 to 50 parts by mass, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of silica.
When the resol type phenolic resin contained in the coating material has a preferable lower limit value or more, kneadability of silica with rubber is improved. When the resol type phenolic resin contained in the coating material has a preferable upper limit value or less, physical properties as a rubber product such as breaking strength and hardness are not deteriorated. When the amount of the resol type phenol resin is within the above-mentioned preferable range, it is easy to achieve both reduction in rolling resistance and steering stability when a tire is formed.

When the second coating material contains both (A) a novolak type phenolic resin, a curing agent, and (B) a resole type phenolic resin, the coating amount of the second coating material is set in the coating material applied to silica. The total amount of the novolac type phenol resin and the resol type phenol resin contained in is preferably 0.5 to 50 parts by mass, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of silica.
When the total of the novolak-type phenol resin and the resol-type phenol resin contained in the coating material is equal to or more than the preferable lower limit value, the kneadability of silica to rubber is improved. When the total of the novolac type phenol resin and the resol type phenol resin contained in the coating material is not more than the preferable upper limit value, physical properties as a rubber product such as breaking strength and hardness are not deteriorated. When the total amount of the novolac type phenol resin and the resol type phenol resin is within the above-mentioned preferable range, when the tire is used, the reduction of the rolling resistance of the tire and the driving stability of the vehicle are easily compatible.

As the first coating material and the second coating material, materials diluted or dispersed with an appropriate solvent or dispersion medium may be used as necessary. As the solvent or dispersion medium, water, methanol, acetone, methyl ethyl ketone, or the like can be used.
When the first coating material contains a silane coupling agent, the silane coupling agent may be premixed with other components contained in the first coating material and mixed with silica, or the silane coupling agent May be mixed with silica alone, and then other components contained in the first coating material may be mixed.
For mixing the silica and the respective coating materials, apparatuses such as a batch mixer and a continuous mixer can be used. These devices may be used at room temperature or with heating as necessary. In particular, when a solid material is used for each coating material, it is preferable to use the apparatus after heating because the mixing operation can be easily performed.
If necessary, the silica obtained after adding and mixing the second coating material may be dried by a known dryer or the like. What is necessary is just to determine the drying temperature and drying time in that case suitably by the solvent or dispersion medium to be used, the dilution amount of material, etc.

The phenols in the first coating material are phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, allylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol And (A) the novolac type phenol resin and the curing agent in the second coating material, the novolac type phenol resin is phenol, resorcin, cresol, xylenol, propyl. Phenol, butylphenol, octylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew At least one phenol selected from the group consisting of tschel oil, gallic acid, eugenol, and urushiol, and at least one aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, glyoxal, benzaldehyde, and salicylaldehyde With a catalyst such as hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type It is preferably at least one selected from the group consisting of phenolic resins, urethane resins, and epoxy resins.
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenols in the first coating material are phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, allylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol And (B) the resole type phenolic resin in the second coating material is phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, phenylphenol, bromo Phenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol, and Reaction of at least one phenol selected from the group consisting of luciol and at least one aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, glyoxal, benzaldehyde, and salicylaldehyde in the presence of an alkali catalyst. It is preferred that
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenols in the first coating material are phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, allylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol And (A) the novolac type phenol resin and the curing agent in the second coating material, the novolac type phenol resin is phenol, resorcin, cresol, xylenol, propyl. Phenol, butylphenol, octylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew At least one phenol selected from the group consisting of tschel oil, gallic acid, eugenol, and urushiol, and at least one aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, glyoxal, benzaldehyde, and salicylaldehyde With a catalyst such as hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type (B) resol type phenol resin in the second coating material, which is at least one selected from the group consisting of phenol resin, urethane resin, and epoxy resin At least selected from the group consisting of phenol, resorcin, cresol, xylenol, propylphenol, butylphenol, octylphenol, phenylphenol, bromophenol, bisphenol A, bisphenol F, cardanol, cashew nut shell oil, gallic acid, eugenol, and urushiol It is preferable to react one kind of phenol with at least one kind of aldehyde selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, glyoxal, benzaldehyde, and salicylaldehyde in the presence of an alkali catalyst.
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenols in the first coating material are at least one selected from the group consisting of cresol, allylphenol, cardanol, and cashew nut shell oil, and (A) the novolac type phenol resin and the curing agent in the second coating material Of these, the novolac type phenolic resin is an acid catalyst comprising at least one phenol selected from the group consisting of phenol, cresol, cardanol, butylphenol, octylphenol, and bisphenol A, and aldehydes of formaldehyde and / or paraformaldehyde. Preferably, the curing agent is at least one selected from the group consisting of hexamethylenetetramine, hexamethoxymethylmelamine, and 4,4′-diaminodiphenylmethane.
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenol in the first coating material is at least one selected from the group consisting of cresol, allylphenol, cardanol, and cashew nut shell oil, and (B) the resol type phenol resin in the second coating material is phenol, It is preferable that at least one phenol selected from the group consisting of cresol, cardanol, butylphenol, and octylphenol is reacted with aldehydes of formaldehyde and / or paraformaldehyde in the presence of an alkali catalyst.
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenols in the first coating material are at least one selected from the group consisting of cresol, allylphenol, cardanol, and cashew nut shell oil, and (A) the novolac type phenol resin and the curing agent in the second coating material Of these, the novolac type phenolic resin is an acid catalyst comprising at least one phenol selected from the group consisting of phenol, cresol, cardanol, butylphenol, octylphenol, and bisphenol A, and aldehydes of formaldehyde and / or paraformaldehyde. A second coating material that is reacted in the presence of at least one selected from the group consisting of hexamethylenetetramine, hexamethoxymethylmelamine, and 4,4′-diaminodiphenylmethane. (B) the presence of an alkali catalyst in which the resol type phenol resin in (B) is at least one phenol selected from the group consisting of phenol, cresol, cardanol, butylphenol, and octylphenol, and aldehydes of formaldehyde and / or paraformaldehyde The reaction is preferably carried out under the following conditions.
As a curing agent for the first coating material, hexamethylenetetramine, hexamethoxymethylmelamine, paraformaldehyde, formaldehyde, glyoxal, trioxane, 4,4'-diaminodiphenylmethane, acetaldehyde ammonia, resol type phenolic resin, urethane resin, and epoxy resin And at least one selected from the group consisting of aminosilanes such as 3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane; 3-glycidoxypropyltrimethoxy as silane coupling agents; Silanes and epoxy silanes such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; Methacryloxy silanes such as tacryloxypropylmethyldimethoxysilane and 3-methacryloxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane Or at least one selected from the group consisting of sulfide silanes such as bis (triethoxysilylpropyl) tetrasulfide may be added.

The phenol in the first coating material is cresol or cardanol, and among the (A) novolac type phenol resin and the curing agent in the second coating material, the novolac type phenol resin is phenol and / or cardanol and formaldehyde. Are preferably reacted in the presence of an acid catalyst, and the curing agent is preferably hexamethylenetetramine or 4,4′-diaminodiphenylmethane. Hexamethylenetetramine may be added to the first coating material as a curing agent, and 3-aminopropyltriethoxysilane may be added as a silane coupling agent.
Alternatively, the phenols in the first coating material are cresol or cardanol, and the (B) resol type phenol resin in the second coating material contains phenol and / or cardanol and formaldehyde in the presence of an alkali catalyst. It is preferable to have reacted. Hexamethylenetetramine may be added to the first coating material as a curing agent, and 3-aminopropyltriethoxysilane may be added as a silane coupling agent.
Furthermore, the phenols in the first coating material are cresol or cardanol, and among the (A) novolac type phenol resin and the curing agent in the second coating material, the novolac type phenol resin is phenol and / or cardanol. And formaldehyde are reacted in the presence of an acid catalyst, the curing agent is hexamethylenetetramine, or 4,4′-diaminodiphenylmethane, and (B) resol type phenolic resin is phenol or cardanol and formaldehyde Is preferably reacted in the presence of an alkali catalyst. Hexamethylenetetramine may be added to the first coating material as a curing agent, and 3-aminopropyltriethoxysilane may be added as a silane coupling agent.

<Rubber composition>
The rubber composition of the present invention contains the resin-coated silica of the present invention and a rubber.
(Rubber)
Examples of the rubber include natural rubber; diene rubbers such as styrene butadiene rubber, polyisoprene rubber, polybutadiene rubber, and ethylene butadiene rubber.

The content of the resin-coated silica in the rubber composition is preferably 10 to 200 parts by weight and more preferably 30 to 150 parts by weight with respect to 100 parts by weight of the rubber.
When the content of the resin-coated silica is not more than the preferable upper limit value, the resin-coated silica and the rubber are easily mixed well. When the content of the resin-coated silica is equal to or more than the preferable lower limit, the rolling resistance of the tire can be reduced when the tire is formed. In addition, when the content of the resin-coated silica is within the above-described preferable range, it is easy to achieve both reduction in rolling resistance of the tire and driving stability of the vehicle when the tire is used.

The rubber composition may contain components other than the resin-coated silica and rubber.
In addition to the resin-coated silica, a reinforcing material such as carbon black, aluminum hydroxide, alumina, calcium carbonate, mica, and clay may be used in combination with the rubber composition. These reinforcing materials may be those whose surfaces are untreated or those whose surfaces are treated with a known silane coupling agent or the like.
Further, the rubber composition includes a reinforcing resin such as a phenol resin; a curing agent such as hexamethylenetetramine and hexamethoxymethylmelamine; a rubber crosslinking agent such as sulfur and 4,4′-diaminodiphenylmethane; a vulcanization accelerator. Compounding ingredients usually used in the rubber industry such as anti-aging agent, plasticizer, various oils, wax, stearic acid, and zinc oxide may be used.

A rubber composition in an unvulcanized state (unvulcanized rubber composition) is obtained by kneading resin-coated silica, rubber, and other compounding components as necessary with a device such as a Banbury mixer, a roll, or a kneader. Can be manufactured.
Further, a rubber composition in a vulcanized state is prepared by filling an unvulcanized rubber composition in a predetermined mold and preferably performing a heat treatment (vulcanization) at 130 to 180 ° C. for 5 to 60 minutes. (Vulcanized rubber composition) is obtained.

The rubber composition of the present invention can be used for tires, belts, rubber crawlers, anti-vibration rubbers, hoses, mats, marine fences, and the like. Especially, it is suitable for tires and is particularly suitable for tire tread parts.

<Tire>
The tire of the present invention uses the rubber composition of the present invention in a tire tread portion.
Such a tire is manufactured by a usual method. Specifically, the rubber composition of the present invention processed in an unvulcanized state into a predetermined shape of a tire tread portion, and a rubber composition prepared for each member of a tire are in an unvulcanized state These are processed in a predetermined shape and bonded to each other by a tire molding machine to form a raw tire (unvulcanized state), which is then heated and pressurized in a vulcanizer.

When producing an unvulcanized rubber composition, it is better to use the resin-coated silica of the present invention than to use a conventional silane coupling agent containing a polysulfide structure or silica surface-treated only with a phenol resin. The kneadability of silica with rubber is good. Further, the vulcanized rubber composition using the resin-coated silica of the present invention improves the fuel consumption and operation of the vehicle by reducing the rolling resistance of the tire, compared to the vulcanized rubber composition using the conventional surface-treated silica. Both stability and excellent hardness. These reasons are presumed as follows.

In the resin-coated silica of the present invention, the silica is directly coated with the first coating material containing phenols. Phenols have a hydrophilic phenolic hydroxyl group and a lipophilic phenyl group. And this hydrophilic phenolic hydroxyl group and the silanol group of the silica surface are couple | bonded firmly by a hydrogen bond. As a result, the polarity of the silica surface coated with the first coating material is lower than the polarity of the surface of the silica alone, and the adhesion between the silica and the second coating material is increased. It becomes easy to coat with a coating material. Furthermore, phenols have a significantly lower viscosity or melt viscosity than resins such as phenol resins. Therefore, the silica coating process can be easily performed without diluting with a solvent or the like.
Further, the resin-coated silica of the present invention is further coated with a second coating material containing at least one of (B) a resol type phenol resin or (A) a novolak type phenol resin and a curing agent, which is a self-hardening resin. ing. Thus, since silica has the coating layer by the 1st and 2nd coating material, the viscosity at the time of kneading | mixing with rubber | gum becomes low, and the kneadability with respect to the rubber | gum of silica improves. In addition, by increasing the affinity between the coating layer and nonpolar or low polarity rubber, the dispersibility of silica in the rubber is improved, thereby improving the fuel efficiency and handling of the vehicle due to the reduction in tire rolling resistance. Both stability is considered excellent.
Furthermore, when the rubber composition is vulcanized, the second coating material undergoes a curing reaction with the first coating material, and the first coating material and the second coating material are integrated to form silica and A resin coating layer having high adhesion is formed. In addition, the second coating material is integrated with the rubber and the reinforcing resin that is blended as necessary to cause a curing reaction. These actions are considered to provide sufficient hardness to the vulcanized rubber composition.

The resin-coated silica of the present invention is easy to produce as described above. Furthermore, the vulcanized rubber composition using the resin-coated silica of the present invention is superior in hardness and has the same breaking strength as the conventional vulcanized rubber composition using the surface-treated silica. It has sufficient strength as a rubber product.
As described above, by using the resin-coated silica of the present invention as a tire raw material, it is possible to provide a tire that satisfies both environmental performance and safety.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
<Evaluation>
In this example, the kneadability of the unvulcanized rubber composition was evaluated by the following method.
Further, the storage elastic modulus, loss tangent (tan δ), hardness and breaking strength of the vulcanized rubber composition were measured by the following methods.

[Kneadability]
For unvulcanized rubber composition, after measuring the relationship between torque and time (torque-time curve) at 150 ° C. using a curast meter (manufactured by JSR, CURELASTOMETER MODELIII), after the rubber composition has melted The kneadability was evaluated by determining the curast minimum torque (N · m) before vulcanization. The smaller the value of this curast minimum torque, the better the kneading property.

[Storage modulus, loss tangent (tan δ)]
The vulcanized rubber composition was measured for the storage elastic modulus and loss tangent (tan δ) at 70 ° C. at a frequency of 10 Hz using DMS110 manufactured by SSI Nanotechnology.
The higher the value of the storage elastic modulus, the better the driving stability of the automobile when a tire is used. The smaller the value of tan δ, the smaller the rolling resistance of the tire.

[Hardness]
The hardness (Shore A) of the vulcanized rubber composition was measured according to JIS K6253 using a type A durometer GS-719G manufactured by Teclock. It means that it is excellent in the hardness provision effect, so that the measured value of this hardness is high.

[Breaking strength]
With respect to the vulcanized rubber composition, the breaking strength (MPa) of a test piece having a dumbbell shape No. 3 was measured according to JIS K6251 using a strograph V10-C manufactured by Toyo Seiki. The higher the value of the breaking strength, the better the strength.

<Materials used for silica surface treatment>
Silica (a): Ultrasil VN3 (trade name, manufactured by Degussa), wet silica having a nitrogen adsorption specific surface area of 205 m ² / g by BET method.
Silica (b): Zeosil 1115MP (trade name, manufactured by Rhodia), wet silica having a nitrogen adsorption specific surface area of 115 m ² / g by BET method.
Orthocresol: Orthocresol (trade name, manufactured by Nippon Steel Chemical Co., Ltd.).
Cardanol: Cardanol (trade name, manufactured by Golden Cashew products pvt. Ltd.).
Silane coupling agent (1): 3-aminopropyltriethoxysilane KBE-903 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).
Novolac type phenolic resin (1): PS-6230 (trade name, manufactured by Gunei Chemical Industry Co., Ltd .; cardanol-phenol-formaldehyde resin, softening point 85 ° C.) in a 50% by mass methanol solution.
Novolac type phenol resin (2): PSK-2320 (trade name, manufactured by Gunei Chemical Industry Co., Ltd .; phenol-formaldehyde resin, softening point 90 ° C.) in a 50% by mass methanol solution.
Curing agent (1): 10% by mass aqueous solution of hexamethylenetetramine (manufactured by Mitsubishi Gas Chemical Company).
Curing agent (2): 4,4′-diaminodiphenylmethane, Sumicure M (trade name, manufactured by Sumitomo Chemical Co., Ltd.) in a 10% by mass methanol solution.
Resol type phenol resin: PL-6507 (trade name, manufactured by Gunei Chemical Industry Co., Ltd .; cardanol-phenol-formaldehyde resin, methanol solution having a solid content of 50% by mass).
Silane coupling agent (2): 50% by mass methanol solution of bis (triethoxysilylpropyl) tetrasulfide KBE-846 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.).

<Materials used for production of rubber composition>
Silica (a1) to (a9): Surface-treated silica of Examples 1 to 5, 7, and 8 and Comparative Examples 1 to 2.
Silica (b1): The surface-treated silica of Example 6.
Natural rubber: RSS No. 3 Wax: Sunnock wax (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.).
Oil: Diana Process AH40 (trade name, manufactured by Idemitsu Kosan Co., Ltd.).
Anti-aging agent: NOCRACK 6C (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.).
Stearic acid: Sakura stearate (trade name, manufactured by NOF Corporation).
Zinc flower: Zinc oxide (manufactured by Sakai Chemical Co., Ltd.).
Novolac type phenolic resin (3): PS-4569 (trade name, manufactured by Gunei Chemical Industry Co., Ltd .; cashew modified phenol-formaldehyde resin, melting point 72 ° C.).
Sulfur: Sulfur (manufactured by Tsurumi Chemical Co., Ltd.).
Curing agent (1): 10% by mass aqueous solution of hexamethylenetetramine (manufactured by Mitsubishi Gas Chemical Company).
Vulcanization accelerator: Noxeller NS-P (trade name, manufactured by Ouchi Shinsei Chemical Co., Ltd.).

<Silica surface treatment>
According to the composition shown in Table 1, each material was stirred and mixed to prepare surface-treated silica.
In Table 1, the blending amount of each material indicates the amount of the material itself (the amount as a solution when the material is a solution) with respect to 100 parts by mass of silica.

Example 1
2.7 parts by mass of cardanol was added to 100 parts by mass of silica (a), and the mixture was stirred and mixed with a Henschel mixer. Next, 12.6 parts by mass of the novolac-type phenol resin (1) (50% by mass methanol solution) and 9.0 parts by mass of the curing agent (1) (10% by mass aqueous solution) are added with stirring and mixed in a hot air dryer. The surface-treated silica (a1) was obtained by drying at 90 ° C. for 1 hour.

(Example 2)
To 100 parts by mass of silica (a), 4.5 parts by mass of ortho-cresol was added and mixed by stirring with a Henschel mixer. Next, 9.0 parts by mass of the novolac-type phenol resin (1) (50% by mass methanol solution) and 9.0 parts by mass of the curing agent (1) (10% by mass aqueous solution) are added with stirring and mixed in a hot air dryer. The surface-treated silica (a2) was obtained by drying at 90 ° C. for 1 hour.

(Example 3)
To 100 parts by mass of silica (a), 4.5 parts by mass of cardanol was added and stirred and mixed with a Henschel mixer. Next, 9.0 parts by mass of the novolak-type phenol resin (2) (50% by mass methanol solution) and 9.0 parts by mass of the curing agent (1) (10% by mass aqueous solution) are added with stirring and mixed in a hot air dryer. The surface-treated silica (a3) was obtained by drying at 90 ° C. for 1 hour.

Example 4
2.7 parts by mass of cardanol was added to 100 parts by mass of silica (a), and the mixture was stirred and mixed with a Henschel mixer. Next, 12.6 parts by mass of a resol type phenol resin (50% by mass methanol solution) was added, mixed by stirring, and dried by a hot air dryer at 90 ° C. for 1 hour to obtain surface-treated silica (a4). It was.

(Example 5)
To 100 parts by mass of silica (a), 2.0 parts by mass of the silane coupling agent (1) and 1.5 parts by mass of cardanol were added and stirred and mixed with a Henschel mixer. Next, 3.0 parts by mass of the novolac-type phenolic resin (1) (50% by mass methanol solution) and 3.0 parts by mass of the curing agent (1) (10% by mass aqueous solution) are added with stirring and mixed in a hot air dryer. The surface-treated silica (a5) was obtained by drying at 90 ° C. for 1 hour.

(Example 6)
Surface-treated silica (b1) was obtained in the same manner as in Example 5 except that the silica (a) was changed to silica (b).

(Example 7)
To 100 parts by mass of silica (a), 2.0 parts by mass of silane coupling agent (1), 4.5 parts by mass of cardanol, and 4.5 parts by mass of curing agent (1) (10% by mass aqueous solution) are added. The mixture was stirred and mixed with a Henschel mixer. Next, 9.0 parts by mass of the novolac-type phenolic resin (1) (50% by mass methanol solution) and 4.5 parts by mass of the curing agent (1) (10% by mass aqueous solution) were added with stirring and mixed in a hot air dryer. The surface-treated silica (a6) was obtained by drying at 90 ° C. for 1 hour.

(Example 8)
To 100 parts by mass of silica (a), 2.0 parts by mass of the silane coupling agent (1) and 4.5 parts by mass of cardanol were added and stirred and mixed with a Henschel mixer. Next, 9.0 parts by mass of novolac-type phenol resin (1) (50% by mass methanol solution), 4.5 parts by mass of curing agent (1) (10% by mass aqueous solution) and curing agent (2) (10% by mass methanol solution) ) 4.5 parts by mass was added, mixed with stirring, and dried in a hot air dryer at 90 ° C. for 1 hour to obtain surface-treated silica (a7).

(Comparative Example 1)
Add 16.0 parts by mass of the silane coupling agent (2) (50% by mass methanol solution) to 100 parts by mass of silica (a), stir and mix with a Henschel mixer, and 130 ° C. for 1 hour with a hot air dryer. By drying, surface-treated silica (a8) was obtained.

(Comparative Example 2)
In 100 parts of silica (a), 2.0 parts by mass of a silane coupling agent (1) and 20.0 parts by mass of a novolac type phenol resin (2) (50% by mass methanol solution) are added, and a Henschel mixer is used. The mixture was stirred and mixed, and dried by hot air dryer at 90 ° C. for 1 hour to obtain surface-treated silica (a9).

<Manufacture of rubber composition>
According to the composition shown in Table 2, each material was kneaded to prepare an unvulcanized rubber composition. Moreover, the unvulcanized rubber composition was heated in a mold to obtain a vulcanized rubber composition.
In Table 2, the blending amount of each material indicates the amount of the material itself (the amount as a solution when the material is a solution) with respect to 100 parts by mass of natural rubber.

Example 9
100 parts by weight of natural rubber, 85 parts by weight of silica (a1), 2 parts by weight of wax, 4 parts by weight of oil, 2 parts by weight of anti-aging agent, 4 parts by weight of stearic acid, 5 parts by weight of zinc white, 10 parts by mass of the novolac type phenol resin (3) was kneaded in a pressure kneader at 150 ° C. for 5 minutes. To the obtained kneaded product, 2.5 parts by mass of sulfur, 5 parts by mass of the curing agent (1) (10% by mass aqueous solution), and 1.5 parts by mass of the vulcanization accelerator were added. By kneading at 90 ° C. for 5 minutes, a sheet-like unvulcanized rubber composition was obtained.

Next, the obtained unvulcanized rubber composition was put in a 150 mm × 150 mm × 2 mm mold and heated at 150 ° C. for 40 minutes to obtain a vulcanized rubber composition.

(Examples 10 to 16, Comparative Examples 3 to 4)
Unvulcanized rubber composition and vulcanized rubber in the same manner as in Example 9, except that silica (a1) was changed to silica (a2) to (a5), (b1), (a6) to (a9), respectively. A composition was obtained.

The curast minimum torque was determined for the unvulcanized rubber composition of each example by the above evaluation method. Further, the storage elastic modulus, tan δ, hardness and breaking strength of the vulcanized rubber composition were measured. The results are shown in Table 2.

From the results shown in Table 2, the unvulcanized rubber compositions of Examples 9 to 16 were compared with the unvulcanized rubber compositions of Comparative Examples 3 and 4 until the rubber composition was melted and vulcanized. From the fact that the value of the minimum torque is small, it can be seen that the kneadability at the time of producing the rubber composition is good.
In addition, the vulcanized rubber compositions of Examples 9 to 16 have a higher storage elastic modulus and a smaller tan δ value than the vulcanized rubber compositions of Comparative Examples 3 and 4, and therefore, steering stability. It can be seen that the effect of improving the fuel efficiency of the automobile due to the reduction in tire rolling resistance is also high.

Further, since the vulcanized rubber compositions of Examples 9 to 16 have higher hardness values than the vulcanized rubber compositions of Comparative Examples 3 and 4, the surface-treated silica of Examples 1 to 8 was used. It can be seen that (resin-coated silica) is excellent in hardness imparting effect.
In addition, since the vulcanized rubber compositions of Examples 9 to 16 have a breaking strength equal to or higher than the vulcanized rubber compositions of Comparative Examples 3 and 4, they have practically sufficient strength as rubber products. It can be said that.

Claims

A resin-coated silica in which silica having a nitrogen adsorption specific surface area of 50 to 300 m 2 / g according to the BET method is sequentially coated with a first coating material and a second coating material,
The first coating material comprises phenols;
The resin-coated silica, wherein the second coating material includes (A) at least one of a novolac type phenol resin and a curing agent, and (B) a resol type phenol resin.
The resin-coated silica according to claim 1, wherein the first coating material contains a curing agent.
The resin-coated silica according to claim 1 or 2, wherein the first coating material contains a silane coupling agent.
A rubber composition comprising the resin-coated silica according to claim 1 and rubber.
A tire using the rubber composition according to claim 4 in a tire tread portion.