KR20200018571A - Water-containing silicic acid for rubber reinforcement filling and preparation method thereof - Google Patents

Abstract

The present invention relates to a hydrous silicic acid for rubber reinforcement filling, wherein the surface solid acid density is in the range of 1.8 to 2.4 m-mol / m 2 and contains a cationic or nonionic surfactant. In another aspect, the present invention, in the step of producing a hydrous silicic acid, the addition of aluminate, and then adding a cationic or nonionic surfactant, the hydrous silicate for filling rubber reinforcement It relates to a method for producing. According to the present invention, it is possible to provide a rubber-reinforced filling hydrous silicic acid which can provide a rubber composition with further improved wear resistance than before.

Description

Water-containing silicic acid for rubber reinforcement filling and preparation method thereof

The present invention relates to hydrous silicic acid for rubber reinforcement filling. In detail, it is a filling hydrous silicic acid for rubber reinforcement which is effective in improving the reinforcement property of diene rubber using a silane coupling agent. The hydrous silicic acid of the present invention is useful as a reinforcement for rubber industrial products such as treads or belts for tires, in which rubber reinforcement (particularly wear resistance) is required.

In general, hydrous silicic acid is known under the name of white carbon and has been used as a rubber reinforcing filler since ancient times with carbon black. The hydrous silicic acid is excellent in heat aging resistance, tear resistance, bending crack resistance, adhesiveness, and the like of vulcanized rubber. On the other hand, dispersibility is worse than that of carbon black, the viscosity of the blend is high and the processability is poor at the time of high filling compounding, and the reinforcement (particularly wear resistance) is inferior in general rubber properties. In order to eliminate these drawbacks, the combined use of a silane coupling agent, other organic compound, etc. is performed. However, hydrous silicic acid has not been obtained which can provide satisfactory rubber properties. Therefore, the further modification of hydrous silicic acid is strongly requested | required with the study of a rubber compounding prescription. The hydrous silicic acid which can improve the wear resistance of rubber | gum is disclosed by patent documents 1 and 2, for example.

The present inventors have studied diligently from the viewpoint of controlling the pore structure of hydrous silicic acid and easily invading rubber molecules into the pores of hydrous silicic acid, and from the viewpoint of strengthening the chemical bond between the surface of hydrous silicic acid and rubber molecules. It carried out and found and patented that the hydrous silicic acid which made the pore structure of hydrous silicic acid the predetermined structure can provide the rubber composition which has the outstanding wear resistance which has not existed until now (patent document 3).

JP 2000-302912 A JPH 11-236208 A JP 2017-002210 A WO2013 / 168424 A

However, in the market in which a rubber composition relates, for example, a tire market, there is a demand for a rubber composition with improved wear resistance than in the related art with respect to environmental problems and energy problems. Therefore, there is a demand for hydrous silicic acid for rubber reinforcement filling which can provide such a rubber composition. For example, it is desired to provide a rubber reinforcing filler hydrous silicic acid which can provide a rubber composition with improved wear resistance more than the rubber reinforcing filler hydrous silicic acid described in Patent Document 3.

An object of the present invention is to provide a hydrous silicic acid for rubber reinforcement filling which can provide a rubber composition with improved wear resistance even more conventionally.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined from the point of view of improving reinforcement by paying attention to the reactivity of a silane coupling agent and hydrous silicic acid, efficiently combining hydrous silicic acid and a rubber molecule, and also improving dispersibility. As a result, the solid acid density on the surface of the hydrous silicic acid is important for the bonding of the hydrous silicic acid surface and the rubber molecule via the silane coupling agent. However, only the adjustment of the surface solid acid density can significantly improve the wear resistance. In addition to adjusting the surface solid acid density in a predetermined range, by adding a predetermined surfactant, it is possible to provide a hydrous silicic acid which can be remarkably improved with respect to diene rubber in combination with a silane coupling agent. I found something.

That is, the present inventors are excellent in rubber | gum by containing a predetermined surfactant in hydrous silicic acid which has a surface solid acid density of a predetermined range regarding provision of abrasion resistance to the rubber composition which used the silane coupling agent of hydrous silicic acid together. By improving the dispersibility of the hydrous silicic acid having reinforcement to rubber with a predetermined surfactant, the present inventors have found that the wear resistance that the hydrous silicic acid can impart to the rubber composition can be remarkably improved. .

The present invention is a hydrous silicic acid having a surface solid acid density in the range of 1.8 to 2.4 m-mol / m 2, and containing a predetermined surfactant, wherein the hydrous silicic acid is used in combination with a silane coupling agent. By mix | blending with a rubber composition, compared with the past, it succeeded in obtaining the rubber composition which remarkably improved wear resistance.

The hydrous silicic acid for rubber reinforcement filling of the present invention has a surface solid acid density in an effective range for promoting chemical bonding with rubber molecules via a silane coupling agent in order to improve wear resistance, and contains a predetermined surfactant. By this, the greatest feature is to remarkably improve the wear resistance to the rubber composition.

The present invention is as follows.

[1] A hydrous silicic acid for rubber reinforcement filling, wherein the surface solid acid density is in the range of 1.8 to 2.4 m-mol / m 2 and contains a cationic or nonionic surfactant.

[2] The hydrous silicic acid for rubber reinforcement filling according to [1], which is for reinforcing filling of a diene rubber composition using a silane coupling agent together.

[3] The hydrous silicic acid for rubber reinforcement filling according to [1] or [2], wherein the CTAB specific surface area is from 130 to 300 m 2 / g.

[4] The water-containing silicic acid for rubber reinforcement filling according to [3], wherein the ratio of the amount of the surfactant (mass part / 100 SiO ₂ mass part (solid content basis)) and the CTAB specific surface area (m 2 / g) is in the range of 0.001 to 0.01. .

[5] In any one step of the process for producing hydrous silicic acid,

The manufacturing method of the water reinforcing filler hydrous silicic acid as described in any one of [1]-[4] including adding an aluminate and then adding a cationic or nonionic surfactant.

[6] The process for producing hydrous silicic acid includes any one of steps of adding an acid continuously from the completion of addition of the aqueous alkali silicate solution, performing filtration washing with water, and drying step, and any of these steps. The manufacturing method as described in [5] in which an aluminate is added and a surfactant is added after that.

[7] The aluminate is sodium aluminate, the sodium aluminate has a Na ₂ O / Al ₂ O ₃ molar ratio of 1.8 to 20.0 and an Al ₂ O ₃ concentration of 1.0 to 16.0% by weight [5] or [6] The manufacturing method described in.

[8] The production method according to any one of [5] to [7], wherein the surfactant is added as an aqueous solution in the range of 20 to 90% by weight based on solid content.

[9] The step of forming hydrous silicic acid in an aqueous solution is performed by adding an aqueous alkali silicate solution and sulfuric acid to 70 to 90 ° C. in an aqueous alkali solution of silicate heated to 70 to 90 ° C. having a SiO ₂ concentration of 5 to 50 g / l and a pH of 10 to 12 ° C. When the temperature is added, the neutralization reaction is performed while controlling the addition amount (ratio) of the aqueous alkali silicate solution and sulfuric acid so that the pH of the reaction solution is determined in the range of 10 to 11, and the SiO ₂ concentration is in the range of 50 to 80 g / L. The manufacturing method in any one of [5]-[8] including performing the said addition until.

The hydrous silicic acid for rubber reinforcement filling of the present invention can improve the reinforcement (particularly wear resistance) of rubber when blended with natural rubber, synthetic rubber, for example, diene rubber, and thus has a high demand for wear resistance. It can be usefully used as a reinforcing filler for rubber industrial products, such as a tire and a belt.

<Hydrogenic acid for rubber reinforcement filling>

The hydrous silicic acid for rubber reinforcement filling of the present invention,

(A) the surface solid acid density is in the range of 1.8 to 2.4 m-mol / m 2, and

(B) It is characterized by containing a surfactant.

The hydrous silicic acid of the present invention has a high reactivity with the silane coupling agent and is added to the rubber composition together with the silane coupling agent to provide a rubber composition having excellent reinforcement property (especially wear resistance). Instead, the surface solid acid density is in a predetermined range (1.8 to 2.4 m-mol / m 2).

Conventionally, a silane coupling agent is widely used when mix | blending hydrous silicic acid in order to improve the dispersibility of hydrous silicic acid and rubber | gum. In the reaction between the hydrous silicic acid and the silane coupling agent, first, a hydrolysis group of the silane coupling agent undergoes a hydrolysis reaction to generate a silanol group (-SiOH), and the silanol group of the silane coupling agent and the silanol group present on the surface of the hydrous silicic acid are dehydrated. The condensation reaction binds to the hydrous silicic acid surface. It is known that these reactions are generally accelerated under acidic or alkaline conditions.

When another atom such as aluminum is blown into the hydrous silicic acid, it is known to become a solid acid by localization of charges around the atom. When a solid acid is present on the surface of hydrous silicic acid, it becomes a surface solid acid and expresses an acid catalyst effect.

Surface solid acids can be expected to express catalysis on the surface of hydrous silicic acid and to promote the reaction of hydrous silicic acid and silane coupling agent. In the past, there have been examples of the amount of the surface solid acid. However, in the present invention, in view of the fact that the surface solid acid acts as a catalyst, it was considered important to be distributed at a certain density with respect to the surface of hydrous silicic acid. That is, the catalysis was expected to promote the binding of the hydrous silicic acid and the silane coupling agent when the solid acid is present at a constant density on the surface of the hydrous silicic acid, thereby exhibiting a reinforcing improvement effect during rubber compounding.

However, as a result of the present inventor's examination, as shown in Reference Example 1, the presence of a solid acid at a constant density with respect to the surface of the hydrous silicic acid resulted in some reinforcing improvement effect (compared with the hydrous silicic acid of Comparative Example 1). As expected above, a remarkable reinforcement improvement effect at the time of rubber compounding could not be obtained. On the other hand, in the result of the reference example 1, compared with the case where the hydrous silicic acid of the comparative example 1 was used, dispersibility falls, and when this improves, on the expectation that a higher reinforcement improvement effect may be obtained, it references. The experiment of Example 2 was performed. That is, surfactant was used together in order to improve the dispersibility of hydrous silicic acid at the time of rubber compounding. However, as shown in the reference example 2, under the conditions of the reference example 2, sufficient dispersibility improvement effect was not acquired, and the reinforcement improvement effect was also not obtained.

On the other hand, as a result of controlling the surface solid acid density, it tried to add predetermined surfactant to the hydrous silicic acid with which dispersibility fell in the step before rubber compounding. As a result, as shown in Examples 1 to 6, no significant improvement in dispersibility was observed (equivalent to Comparative Example 2), but it was found that wear resistance could be remarkably improved. In the hydrous silicic acid of the present invention, it is assumed that the predetermined surfactant is adsorbed on the surface of the hydrous silicic acid, thereby preventing the aggregation of the hydrous silicic acid and improving the dispersibility. It is much more remarkable.

As a method of inhibiting and preventing aggregation of hydrous silicic acid, the addition of a surfactant is widely known, and the surfactant is used during rubber kneading or added to hydrous silicic acid in advance (Patent Document 4). However, until now, in the production of hydrous silicic acid, the aluminum compound for strengthening aggregation and the surfactant used for the purpose of improving the dispersibility have not been used simultaneously. The inventors of the present invention control the surface solid acid density to a predetermined range by using these for the production of hydrous silicic acid in an appropriate manner, and by using a predetermined surfactant, the reactivity of the hydrous silicic acid with the silane coupling agent and the rubber composition It was found that the dispersibility to the resin was improved, and the effect of improving the reinforcement and wear resistance of the larger rubber was obtained.

In the hydrous silicic acid of the present invention, since the surfactant is adsorbed on the surface in advance, when dispersed in the rubber, it is possible to exhibit the maximum aggregation suppression effect or the dispersing effect with the minimum required amount. As a result, the characteristic (dispersion effect of functional silicic acid) of surfactant can be utilized more efficiently compared with the method of adding surfactant in the case of the rubber compounding conventionally performed.

The surface solid acid density of hydrous silicic acid in this invention can be calculated | required from surface solid acid amount and CTAB specific surface area as follows.

Surface solid acid measurement:

To about 0.1 g of hydrous silicic acid dried at 105 ° C. for 2 hours, 10 drops of a benzene solution of methyl red indicator prepared at 0.5 m-mol / L was added dropwise, and 5 ml of benzene was further added. The amount of surface solid acid per 1 g of hydrous silicic acid is calculated | required by titrating using the benzene solution of n-butylamine prepared at 50m-mol / L, and the n-butylamine dripping amount at the time of discoloration to yellow.

In order to have a predetermined surface solid acid density, the hydrous silicic acid of the present invention also depends on the CTAB specific surface area, but the amount of the solid acid is suitably in the range of 300 to 500 m-mol / g, for example.

CTAB specific surface area measurement:

It carries out based on JISK6430 (rubber compounding agent-silica-test method). The CTAB specific surface area is a value (m 2 / g) calculated from the amount adsorbed on hydrous silicic acid by setting the adsorption cross-sectional area of the CTAB molecule to 35 Pa ² .

In order to have a predetermined surface solid acid density, the hydrous silicic acid of the present invention also depends on the amount of solid acid, but the CTAB specific surface area is preferably 130 to 300 m 2 / g, more preferably 150 to 290 m 2 / g, and more preferably. Preferably in the range of 170 to 280 m 2 / g.

Generally, when valences with different valences or electronegativity exist on the surface of hydrous silicic acid, it is known to form surface solid acid points. It is believed that the solid acid present on the surface of the hydrous silicic acid can improve the reinforcement by chemically bonding the rubber molecule and the surface of the hydrous silicic acid via a silane coupling agent.

Al, Ti, Mg, etc. are mentioned as metal ion which forms a solid acid point by blowing into hydrous silicic acid, but aluminum is preferable in consideration of availability, stability, etc. Moreover, as an aluminum source which can be used for hydrous silicic acid manufacture, since it erodes the hydrous silicic acid surface efficiently and blows in, it is preferable that it is alkaline, an aluminate is preferable, and sodium aluminate is used most suitably.

In the present invention, when the surface solid acid density is less than 1.8 m-mol / m 2, the effect of promoting the reaction with the silane coupling agent is insufficient. Thus, the effect of improving the wear resistance over the prior art is not obtained. On the contrary, when it exceeds 2.4 m-mol / m <2>, reactivity becomes too high and there exists a possibility that a silane coupling agent may react locally, and it is unpreferable. The surface solid acid density is preferably in the range of 1.8 m-mol / m 2 or more and 2.35 m-mol / m 2 or less.

Hereinafter, although the kind of surfactant to add is demonstrated, it is limited to the cationic system and / or nonionic surfactant added to the hydrous silicic acid of this invention. Although cationic surfactant and nonionic surfactant may be used independently, they may be used together.

The cationic surfactant is a surfactant having a positive charge when dissolved in water, for example, quaternary ammonium salt, tertiary ammonium salt, secondary ammonium salt, primary ammonium salt, pyridinium salt, amine Salts; and the like. Examples of commercially available cationic surfactants include KOHTAMIN (manufactured by Kao Corporation), CATIOGEN (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like. However, it is not intended to be limited to this.

The said nonionic surfactant is surfactant which has a hydrophilic group which does not ionize when dissolved in water, For example, polyethyleneglycol alkylether, polyethyleneglycol fatty acid ester, alkylglycoside, fatty acid alkanolamide, glycerin fatty acid ester, Alkylglyceryl ether, sorbitan fatty acid ester, polyethylene glycol sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyvinylpyrrolidone , Polyoxyalkylene lauryl ether, polyoxyethylene phenyl ether and the like. Examples of commercially available nonionic surfactants include EMULGEN (manufactured by Kao Corporation), NOIGEN (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like. However, it is not intended to be limited to this.

The amount of the surfactant in the hydrous silicic acid of the present invention is not a problem so long as it is an amount capable of ensuring dispersibility without disturbing the reaction with the silane coupling agent by the surface solid acid, and the surfactant with respect to 100 parts by mass of hydrous silicic acid The ratio of the amount (mass part / 100 SiO ₂ mass part) and the CTAB specific surface area (m 2 / g) on the basis of the solid content may be in the range of 0.001 to 0.010, and preferably in the range of 0.002 to 0.009. Do.

Illustrating the calculation method of the quantity in solid content basis of surfactant, For example, when CTAB specific surface area is hydrous silicic acid of 250 m <2> / g, the addition amount of surfactant (solid content basis) is 250 * per 100 mass parts of hydrous silicic acids. It can calculate in the range of 0.001-250 * 0.01 = 0.25-2.5 (mass part).

As a kind of surfactant, in order to adsorb | suck to a hydrous silicic acid surface efficiently, it must be cationic or nonionic surfactant, and sufficient dispersion effect is not found in anionic surfactant.

In order to process a surfactant uniformly on the surface of hydrous silicic acid, it is preferable to wet-process by the method mentioned later. In the case of the dry treatment in which the surfactant is directly mixed with the hydrous silicic acid dry powder, not only the effect of preventing aggregation by drying, but also the non-uniform treatment is easy, and the effect of improving dispersibility is not sufficiently obtained.

The hydrous silicic acid of the present invention exhibits particularly excellent effects for reinforcing filling of a diene rubber composition using a silane coupling agent in combination. Examples of the silane coupling agent and the diene rubber composition will be described later.

<Method for producing functional silicic acid>

The hydrous silicic acid of the present invention is produced by a method comprising adding aluminate and then adding a cationic or nonionic surfactant in any one of the processes for producing hydrous silicic acid. . It is preferable that aluminate is sodium aluminate from a viewpoint of the availability.

The process for producing the hydrous silicic acid includes, for example, any one of steps of continuously adding an acid from the completion of the addition of the aqueous alkali silicate solution, performing filtration water washing, drying, and any of these steps. In one, the aluminate, preferably sodium aluminate, can be added, followed by the addition of a surfactant. Sodium aluminate is preferably a Na ₂ O / Al ₂ O ₃ molar ratio of 1.8 to 20.0, and an Al ₂ O ₃ concentration of 1.0 to 16.0% by weight. The surfactant is preferably added as an aqueous solution in the range of 20 to 90% by weight based on solids.

The step of forming hydrous silicic acid in the aqueous solution in the production process, for example, alkali silicate aqueous solution and sulfuric acid in an aqueous alkali silicate solution heated to 70 to 90 ℃ having a SiO ₂ concentration of 5 to 50 g / l, pH 10 to 12 Is added at a temperature of 70 to 90 ° C., and the neutralization reaction is carried out while controlling the addition amount (ratio) of the aqueous alkali silicate solution and sulfuric acid so that the pH of the reaction solution is determined in the range of 10 to 11, and the SiO ₂ concentration is 50 to 80 g /. It may comprise performing said addition until it becomes a range of l.

It is known that the wet manufacturing method of hydrous silicic acid of this invention is generally performed by making alkali aqueous silicate aqueous solution react with a photo acid (generally sulfuric acid). The method for producing hydrous silicic acid of the present invention is also basically based on this method. As a particularly preferable aspect, the sulfuric acid excess method of gradually reducing the pH from the start to the end of the reaction easily obtains a hydrous silicic acid having a high CTAB surface area excellent in dispersibility, but is not limited to this method. In order to achieve the object of the present invention, the addition method of aluminum and the addition method of surfactant are also important.

The specific example of each process is as follows.

(a) in the alkali silicate aqueous solution heated to a SiO ₂ concentration of 5 to 50g / ℓ, pH 10 to 12 70 to 90 ℃, the addition of alkali silicate solution and sulfuric acid at a temperature of 70 to 90 ℃, and the reaction solution pH The neutralization reaction is carried out while controlling the addition amount (ratio) of the aqueous alkali silicate solution and sulfuric acid so as to be determined in the range of 10 to 11, and the addition is carried out until the SiO ₂ concentration is in the range of 50 to 80 g / L, and the silicic acid is dissolved in the aqueous solution. Forming process.

(b) A step of stopping the addition of the aqueous alkali silicate solution and continuing adding sulfuric acid until the pH of the reaction solution reaches 5 or less, thereby obtaining a precipitate.

(c) A step of filtering and washing the obtained precipitate to obtain a cake.

(d) If necessary, a step of emulsifying the cake obtained in (c) can be added.

(e) Process of drying and pulverizing the obtained cake or emulsion slurry to obtain hydrous silicic acid powder.

Aluminum and surfactant are added in any of the processes of (b)-(d). When it adds in (a) which is a reaction step, since the aggregation structure of hydrous silicic acid may change and the dispersibility of hydrous silicic acid may deteriorate, it is preferable to set it as the process after (b) after completion | finish of (a).

Moreover, addition of surfactant is more preferable at least before drying, since it may prevent aggregation at the time of drying.

As an aluminum source, aluminate is preferable, and sodium aluminate is optimal. Since the hydrous silicic acid is dissolved in a small amount in the weakly alkaline solution, by adding an alkaline Al ₂ O ₃ solution such as sodium aluminate, only the surface of the hydrous silicic acid is dissolved and aluminum is easily blown.

In addition, the addition of sodium aluminate prepared at a Na ₂ O / Al ₂ O ₃ molar ratio of 1.8 to 20.0 and an Al ₂ O ₃ concentration of 1.0 to 16.0% by weight is most preferable for the reasons described later, in order to uniformly treat the hydrous silicic acid surface. It is preferable to add by wet type | mold, and to stir for 5 minutes or more after addition, and to blow into a hydrous silicic acid surface.

When the Al ₂ O ₃ concentration of sodium aluminate is 1.0% by weight or more, the blowing of aluminum to the hydrous silicic acid surface is sufficient, and when it is 16.0% by weight or less, no aggregation of hydrous silicic acid is caused during addition. Although sodium aluminate is known to cause hydrolysis or crystallization depending on the Al ₂ O ₃ concentration and the Na ₂ O / Al ₂ O ₃ molar ratio in the aqueous solution, it is known that the Al ₂ O ₃ concentration is 1.0 wt% to 16.0. As the percent by weight is Na ₂ O / Al ₂ O ₃ molar ratio is 1.8 or more, is obtained and a stable sodium aluminate solution. The higher the molar ratio, the easier it is to obtain a stable solution, but the higher the molar ratio, the stronger the alkali. If the Na ₂ O / Al ₂ O ₃ molar ratio is 20.0 or less, there is no fear of causing aggregation of hydrous silicic acid. In addition, the lower the molar ratio is preferable as long as stable sodium aluminate is obtained.

Addition of surfactant is performed after adding aluminate. It is preferable to add surfactant which adjusted the solid content reference concentration to the range of 20 to 90 weight%. In order to uniformly process a hydrous silicic acid surface, it is preferable to add surfactant in a slurry (wet process), and to stir for 5 minutes or more after addition, and to uniformly process a hydrous silicic acid surface.

If the solid content reference concentration of the surfactant is 20% by weight or more, adsorption of the surfactant to the hydrous silicic acid surface is satisfactorily performed. If it is 90% by weight or less, the surface of the hydrous silicic acid is uniformly treated, and the aggregation suppression effect can be sufficiently exhibited. . Moreover, when adding in the emulsion slurry of the said (d) process, if it is this concentration range, it can add without causing the phenomenon, such as gelatinization. After the addition, the surfactant is disposed almost evenly on the surface of the hydrous silicic acid, and stirring is preferably performed for at least 5 minutes to suppress aggregation of the hydrous silicic acid.

In the present invention, the order of addition and method of addition of aluminate (eg sodium) and surfactant is important. In the method for producing hydrous silicic acid of the present invention, if the order of addition of aluminate and addition of surfactant is reversed, it is inhibited that aluminum is blown into the surface of hydrous silicic acid and the solid acid is inhibited by the surfactant. A hydrous silicic acid having an abrasion resistance improving effect of was not obtained.

Although the hydrous silicic acid of this invention can be applied as reinforcement filling of various rubber compositions, the reinforcing filling to diene type rubber is preferable. The use of a rubber composition can be widely used in the industrial rubber field | area where abrasion resistance, such as a tire and a belt, is calculated | required.

Although the rubber composition which can use the hydrous silicic acid of this invention is not restrict | limited, The rubber composition may be a rubber composition containing natural rubber (NR) or diene type synthetic rubber alone or in combination thereof. As synthetic rubber, synthetic polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), etc. are mentioned, for example. have. In particular, the hydrous silicic acid of the present invention has a remarkable wear resistance improvement effect in a rubber composition containing a diene synthetic rubber using a silane coupling agent in combination. The hydrous silicic acid of this invention can mix | blend 5-100 mass parts with respect to 100 mass parts of natural rubber and / or diene synthetic rubber. However, it is not intended to be limited to this range.

The said rubber composition can be what added the silane coupling agent. What is used for a rubber composition can illustrate the silane coupling agent, For example, at least 1 is represented by following formula (I)-formula (III).

(Wherein X represents an alkyl group or chlorine atom having 1 to 3 carbon atoms, n represents an integer of 1 to 3, m represents an integer of 1 to 3, p represents an integer of 1 to 9, and q represents an integer of 1 or more). I may have it)

(Wherein X is an alkyl group or chlorine atom having 1 to 3 carbon atoms, Y is a mercapto group, vinyl group, amino group, imido group, glycidoxy group, methacryloxy group or epoxy group, n is an integer of 1 to 3, m is An integer of 1 to 3, p represents an integer of 1 to 9).

Wherein X is an alkyl group or chlorine atom having 1 to 3 carbon atoms, Z is a benzothiazolyl group, N, N-dimethylthiocarbamoyl group or methacrylate group, n is an integer of 1 to 3, m is 1 An integer of 3 to 3, p represents an integer of 1 to 9, and q may have a distribution of an integer of 1 or more.)

Specific examples of the silane coupling agent include bis (3-triethoxysilylpropyl) polysulfide, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ-aminopropyltrimethoxysilane. , γ-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxy Silylpropyl-N, N-dimethylcarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, etc. are mentioned. The compounding quantity of a silane coupling agent is 1-20 mass% with respect to the mass of hydrous silicic acid, Preferably it is 2-15 mass%. However, it is not intended to be limited to this range.

In the case of using the hydrous silicic acid of the present invention in a rubber composition, in addition to the rubber and silane coupling agent described above, carbon black, a softener (wax, oil), an anti-aging agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator and the like, as necessary, may be used. The compounding agent used for the rubber industry can be mix | blended suitably. A rubber composition can prepare the said rubber component, the hydrous silicic acid of this invention, a silane coupling agent, the said carbon black mix | blended as needed, a rubber compounding agent, etc. with kneaders, such as a Banbury mixer.

The rubber composition incorporating the hydrous silicic acid of the present invention can be suitably applied to rubber products such as tires and conveyor belts, and rubber products such as tires and conveyor belts are excellent in reinforcement and wear resistance.

EXAMPLE

EXAMPLES Hereinafter, although an Example and a comparative example are shown and demonstrated in order to demonstrate this invention concretely, it is not limited to these. In addition, the measurement of each physical property value of hydrous silicic acid was implemented by the method shown next.

● Surface solid acid amount / density

To about 0.1 g of hydrous silicic acid dried at 105 ° C. for 2 hours, 10 drops of a benzene solution of methyl red indicator prepared at 0.5 m-mol / L was added dropwise, and 5 ml of benzene was added. It titrated using the benzene solution of n-butylamine prepared at 50m-mol / L, and the surface solid acid amount was computed from the n-butylamine dripping amount at the time of discoloration to yellow. In addition, the surface solid acid density was calculated by dividing the amount of surface solid acid by the CTAB specific surface area.

● CTAB specific surface area

It carried out based on JIS K6430 (rubber compounding agent-silica-test method). However, the adsorption cross-sectional area of CTAB molecules was calculated as 35 Pa ² .

● Formulation

According to the mixing | blending shown in Table 1, the rubber test sample was adjusted with the following kneading procedure.

(i) In a 1.7 L Banbury mixer (KOBELCO), 700 g of the polymer was kneaded (30 seconds), and the compound A of Table 1 was added to give a compound temperature of 140 to 150 ° C at the time of extraction. ) And rotational speed, and took out after kneading for about 5 minutes.

(ii) After cooling the compound at room temperature, the compound B of Table 1 was added, kneaded for about 1 minute and then taken out (the temperature at the time of taking out was 100 ° C. or lower), and sheeting was carried out on an 8-inch open roll. Vulcanizate properties were measured.

● Unvulcanized Property (Scotch Time t5)

Using a Mooney Viscometer VR-1132 (manufactured by Uejima Seisakusho), measured at 125 ° C and an L type rotor.

● Vulcanizer Characteristics (Tensile Strength)

The measurement was performed according to the JIS test method.

● Dispersibility Test

 Measured with Opti Grade's dispergrader.

Magnification 100 times E scale

It calculated | required with the dispersibility index at the time of making X value of the comparative example 1 100. Higher indexes indicate better dispersibility.

● abrasion test

Measured with an acron wear tester.

Inclination: 15 °, load: 6 pounds test count; The wear reduction volume at 1000 revolutions was measured. The measurement result was calculated | required by the abrasion resistance index at the time of making comparative example 1 100. Higher indexes indicate better wear resistance.

In the evaluation of the present invention, the case where the dispersibility index is 100 or more and the wear resistance index is 150 or more, focusing on the dispersibility and wear resistance, A is the case where the dispersibility index is 100 or more and the wear resistance index is 180 or more. S. In addition, the dispersibility index of 100 or more and the wear resistance index of 100 or more and less than 140 have insufficient improvement effect, so that any one of B, the dispersibility index, and the wear index is less than 100 does not show an improvement effect. , C.

(Example 1)

Into a 240 liter jacketed stainless steel vessel equipped with a stirrer, 14 liters (SiO ₂ 150 g / L, SiO ₂ / Na ₂ O mass ratio 3.3) of 80 liters of water and an aqueous sodium silicate solution were charged, and heated to a temperature of 82 ° C. At this time, the SiO ₂ concentration was 22 g / L and the pH was 11.5.

To this aqueous solution, the same aqueous sodium silicate solution and sulfuric acid (18.4 mol / l) were added in excess of sulfuric acid so that the SiO ₂ concentration was 65 g / l and the pH was 10.9 for 100 minutes while maintaining the temperature of 82 ° C ± 1 ° C. The addition of sodium silicate was stopped at 100 minutes.

After the completion of the predetermined neutralization reaction, the same sulfuric acid was added until the pH became 3.0 to obtain a precipitate. The reactant obtained after that was filtered and washed with water to obtain a cake. The cake obtained was emulsified. With respect to the emulsion slurry, a Na ₂ O / Al ₂ O ₃ molar ratio of 5.9, Al ₂ O ₃ concentration of 5.0% by weight of the prepared sodium aluminate aqueous solution of Al ₂ O ₃ / SiO ₂ mass ratio in order to uniformly process a silicate hydrate, a surface It took time enough to add 0.8%. By adding sodium aluminate at a sufficiently low Al ₂ O ₃ concentration, the surface of the hydrous silicic acid can be treated uniformly, and the amount of aluminum blown into the hydrous silicic acid surface increases. After stirring for 10 minutes, aluminum was blown to the surface of hydrous silicic acid, and then cation A (cationic surfactant: polydiaryldimethylammonium chloride) prepared at a solid concentration of 20% by weight was 1.4 in terms of surfactant / SiO ₂ mass ratio (based on solids). % Was added and stirred for 10 minutes. Then, it dried and manufactured hydrous silicic acid and evaluated.

(Example 2)

In a jacket attached to a stainless steel container equipped with a stirrer of 240ℓ, 80ℓ of water and aqueous solution of sodium silicate _{3.5ℓ (SiO 2 150g / ℓ,} SiO 2 / Na 2 O weight ratio of 3.3) is added, heated to a temperature was 72 ℃. At this time, the SiO ₂ concentration was 6.0 g / l, and the pH was 10.9.

To this aqueous solution, the same aqueous sodium silicate solution and sulfuric acid (18.4 mol / l) were added so that the SiO ₂ concentration was 65 g / l for 100 minutes while maintaining the temperature at 72 ° C ± 1 ° C and pH 10.9. Only the addition of sodium silicate was stopped.

After the completion of the predetermined neutralization reaction, the same sulfuric acid was added until the pH became 3.0 to obtain a precipitate. The reactant obtained after that was filtered and washed with water to obtain a cake. The obtained cake was emulsified, and 1.5% of the sodium aluminate aqueous solution prepared at a Na ₂ O / Al ₂ O ₃ molar ratio 3.0 and an Al ₂ O ₃ concentration of 10.0% by weight was added at an Al ₂ O ₃ / SiO ₂ mass ratio. Add as much time as possible. After stirring for 5 minutes to blow aluminum onto the surface of hydrous silicic acid, cation B (cationic surfactant: stearylamine acetate) prepared at 40% by weight of solids was added so as to be 1.5% by surfactant / SiO ₂ mass ratio (based on solids). Then, it stirred for 5 minutes. Then, it dried and manufactured hydrous silicic acid and evaluated.

(Example 3)

The reaction was carried out in the same manner as in Example 2, and only the addition of sodium silicate was stopped at 100 minutes. Was added such that the sulfuric acid and the _{like, Na 2 O / Al 2 O} 3 molar ratio of 3.0, Al ₂ O ₃ 0.8% prepared sodium aluminate solution at a concentration 10.0% by weight as Al ₂ O ₃ / SiO ₂ weight ratio. After stirring for 5 minutes to blow aluminum on the surface of hydrous silicic acid, cation A prepared at 50% by weight of solid content was added so as to be 0.5% by surfactant / SiO ₂ mass ratio (based on solids) and stirred for 5 minutes or more.

Even after completion | finish of surfactant addition, the same sulfuric acid addition continued to obtain a precipitate until it became pH3.0. The reactant obtained after that was filtered and washed with water to obtain a cake. The obtained cake was dried to produce hydrous silicic acid and evaluated.

(Example 4)

Into a 240 liter stainless steel container equipped with a stirrer, 6.0 liters (SiO ₂ 150 g / L, SiO ₂ / Na ₂ O mass ratio 3.3) of 85 liters of water and an aqueous sodium silicate solution were charged, and heated to a temperature of 90 ° C. At this time, the SiO ₂ concentration was 10.0 g / l and the pH was 11.2.

To this aqueous solution, the same aqueous sodium silicate solution and sulfuric acid (18.4 mol / l) were added so that the SiO ₂ concentration was 60 g / l for 100 minutes while maintaining the temperature at 90 ° C ± 1 ° C and pH 10.9. Only the addition of sodium silicate was stopped.

Was added such that the sulfuric acid and the like, Na ₂ O / Al ₂ O ₃ molar ratio of 19.7, a 0.8% aqueous solution of sodium aluminate prepared by Al ₂ O ₃ concentration of 1.0% by weight as Al ₂ O ₃ / SiO ₂ weight ratio. It was added to a stirred for 5 minutes by blowing aluminum silicate hydrate, a surface, and 1.3% for a cation A a solid fraction of 80% by weight of a surface active agent / SiO ₂ weight ratio (based on solids) were added and stirred for at least 5 minutes.

Even after completion | finish of surfactant addition, the same sulfuric acid addition continued to obtain a precipitate until it became pH 3.0. The reactant obtained after that was filtered and washed with water to obtain a cake. The obtained cake was dried to produce hydrous silicic acid and evaluated.

(Example 5)

The obtained cake was emulsified, and 1.5% of the sodium aluminate aqueous solution prepared at a molar ratio of 2.2 Na ₂ O / Al ₂ O _{3 and} 15.0% by weight of Al ₂ O ₃ was added at an Al ₂ O ₃ / SiO ₂ mass ratio. Add as much time as possible. After stirring for 5 minutes, aluminum was blown to the surface of hydrous silicic acid, and then cation C (cationic surfactant: distearyl dimethylammonium chloride) prepared at 75% by weight of solids was 1.5% at a surfactant / SiO ₂ mass ratio (based on solids). It was added to and stirred for 5 minutes. Aside from this operation, hydrous silicic acid was produced in the same manner as in Example 3 and evaluated.

(Example 6)

The obtained cake was emulsified, and 1.5% of the sodium aluminate aqueous solution prepared at a molar ratio of 2.2 Na ₂ O / Al ₂ O _{3 and} 15.0% by weight of Al ₂ O ₃ was added at an Al ₂ O ₃ / SiO ₂ mass ratio. Add as much time as possible. After stirring for 5 minutes, aluminum was blown to the surface of hydrous silicic acid, and then 1.5% of the nonionic (nonionic surfactant: polyoxyethylene oleyl ether) prepared at 80% by weight of solids was surfactant / SiO ₂ mass ratio (based on solids). Was added to, and stirred for 5 minutes. Aside from this operation, hydrous silicic acid was produced in the same manner as in Example 3 and evaluated.

Comparative Example 1 is Nipsil AQ (manufactured by Tososilica). Nipsil AQ is a hydrous silicic acid that is widely used as a rubber reinforcing filler. As shown in Table 2, the dispersibility of the hydrous silicic acid of Examples 1 to 6 was equal to or higher than that of Comparative Example 1, and a significant improvement in wear resistance was confirmed.

(Comparative Example 2)

The reaction was carried out in the same manner as in Example 2, and only the addition of sodium silicate was stopped at 100 minutes. Was added to the sulfuric acid of the same, cation A was adjusted to a solid content of 40% by weight of surface active agent / SiO ₂ weight ratio (solids basis) added to the medium so as to have 1.5%, and the mixture was stirred for at least 5 minutes.

Even after completion | finish of surfactant addition, the same sulfuric acid addition continued to obtain a precipitate until it became pH3.0. The reactant obtained after that was filtered and washed with water to obtain a cake. The obtained cake was dried to produce hydrous silicic acid and evaluated.

(Reference Example 1)

The reaction was carried out in the same manner as in Example 2, and only the addition of sodium silicate was stopped at 100 minutes. While adding the same sulfuric acid, an aqueous sodium aluminate solution adjusted to a Na ₂ O / Al ₂ O ₃ molar ratio 3.0 and an Al ₂ O ₃ concentration of 10.0% by weight was added so that the Al ₂ O ₃ / SiO ₂ mass ratio was 0.8%, and 5 Stir for more than minutes. Thereafter, the obtained reactant was filtered and washed with water to obtain a cake. The obtained cake was dried to produce hydrous silicic acid and evaluated.

(Reference Example 2)

For Reference Example 1, 1.69 phr (1.5% of surfactant active ingredient / SiO ₂ mass ratio) of 40% active ingredient was further added during rubber kneading.

Dispersibility and wear resistance were calculated | required by the index at the time of making the comparative example 1 100. Higher indexes indicate better dispersibility and wear resistance.

A case where the dispersibility index is 100 or more and the wear resistance index is 180 or more is S and 150 or more.

C, dispersibility of 100 or more, and abrasion resistance index of 100 to 140 were used for the case where there was less than 100 in dispersibility and abrasion resistance as B because the improvement of abrasion resistance was inadequate.

As shown in Table 2, Examples 1-6 have the remarkable wear resistance improvement effect compared with the comparative example 1.

In the reference example 1 in which the surface solid acid density is in the range of the present invention, the wear resistance is improved as compared with the comparative example 1, but the dispersibility is lowered, and only by adjusting the surface solid acid density, No significant wear resistance improving effect is obtained. As shown in Reference Example 2, the same cation A as used in Examples 1, 3, and 4 with hydrous silicic acid had the same surface solid acid density as in Reference Example 1, and was kneaded with rubber. Even if kneaded, the wear resistance and the dispersibility are almost the same as those in Reference Example 1. The hydrous silicic acid of the comparative example 2 is equivalent to Examples 10 and 16 of patent document 4, and contains the same cation A as used in Examples 1, 3, and 4. However, the surface solid acid density is outside the scope of the present invention, and a significant improvement in abrasion resistance such as hydrous silicic acid of Examples 1 to 6 is not confirmed. The hydrous silicic acid of Examples 1 to 6 and the hydrous silicic acid of Comparative Example 2 are almost equivalent in dispersibility, or the hydrous silicic acid of Examples 3 and 6 is slightly inferior to the hydrous silicic acid of Comparative Example 2. Nevertheless, the effect of improving the wear resistance of the hydrous silicic acid of Examples 1 to 6 is remarkably higher than that of the hydrous silicic acid of Comparative Example 2.

From these results, the wear resistance improvement effect of the diene rubber composition which uses the silane coupling agent together by the hydrous silicic acid of this invention has surface solid acid density in a predetermined range, and a predetermined surfactant is supported by hydrous silicic acid. It is a synergistic effect obtained by merely adjusting the surface solid acid density to a predetermined range, or adjusting the surface solid acid density to a predetermined range, and kneading the predetermined surfactant with the hydrous silicic acid to obtain a rubber composition. Unexpected effect.

The hydrous silicic acid for rubber reinforcement filling of the present invention is capable of providing a useful rubber composition in the field of industrial rubber, particularly in which wear resistance such as treads and belts of tires is required.

Claims (9)

As hydrous silicic acid for rubber reinforcement filling,
A hydrous silicic acid for rubber reinforcement filling, characterized in that the surface solid acid density is in the range of 1.8 to 2.4 m-mol / m 2 and contains a cationic or nonionic surfactant. The hydrous silicic acid for rubber reinforcement filling of Claim 1 which is for reinforcement filling of the diene type rubber composition which uses a silane coupling agent together. The hydrous silicic acid for rubber reinforcement filling according to claim 1 or 2, wherein the CTAB specific surface area is from 130 to 300 m 2 / g. The hydrous silicic acid for rubber reinforcement filling according to claim 3, wherein the ratio of the content of the surfactant (mass part / 100 SiO ₂ mass part (solid content basis)) to the CTAB specific surface area (m 2 / g) is in the range of 0.001 to 0.01. As a manufacturing method of the hydrous silicic acid for rubber reinforcement filling of any one of Claims 1-4,
In any one step of the process for producing hydrous silicic acid,
A method for producing hydrous silicic acid for rubber reinforcement filling, comprising adding aluminate and then adding a cationic or nonionic surfactant. 6. The process according to claim 5, wherein the process for producing hydrous silicic acid comprises any one of steps of continuously adding an acid from completion of addition of aqueous alkali silicate solution, performing filtration washing, drying step, and these steps. The manufacturing method in any one of Claims which add aluminate and then surfactant. The aluminate salt is sodium aluminate, the sodium aluminate salt has a Na ₂ O / Al ₂ O ₃ molar ratio of 1.8 to 20.0, and an Al ₂ O ₃ concentration of 1.0 to 16.0% by weight. , Manufacturing method. The production method according to any one of claims 5 to 7, wherein the surfactant is added as an aqueous solution in the range of 20 to 90% by weight on a solids basis. Claim 5, wherein to the alkali silicate solution heated to claim 8 according to any one of items, the aqueous solution forming a silicate hydrate, is a 70 to 90 ℃ SiO ₂ concentration of 5 to 50g / ℓ, pH 10 to 12 during, The aqueous alkali silicate solution and sulfuric acid were added at a temperature of 70 to 90 ° C, and the neutralization reaction was performed while controlling the addition amount (ratio) of the aqueous alkali silicate solution and sulfuric acid so that the pH of the reaction solution was in the range of 10 to 11, and the SiO ₂ concentration was A production method comprising performing said addition until it is in the range of 50-80 g / L.