JP6378071B2 - Composite production method, composite, rubber composition, and pneumatic tire - Google Patents

Description

  The present invention relates to a method for producing a composite, a composite, a rubber composition, and a pneumatic tire.

  A method of kneading a porous material into rubber to obtain a rubber composition is known.

  Also known is a method of obtaining a composition by adding water and a slurry containing a porous phyllosilicate dispersed in water to a blend containing a natural rubber latex (see, for example, Patent Document 1).

JP 2000-63567 A

  However, as a result of intensive studies by the present inventor, the vulcanized rubber obtained by vulcanizing a rubber composition obtained by kneading a porous material into the rubber is bonded to the vulcanized rubber component and the porous material. It was found that the porous material may be detached due to its weak nature.

  Moreover, even in the vulcanized rubber obtained by vulcanizing the composition obtained by the technique described in Patent Document 1, there is room for improving the adhesion between the vulcanized rubber component and the phyllosilicate.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a composite as a raw material of vulcanized rubber having excellent adhesion between the vulcanized rubber component and the porous material, and a method for producing the same. is there.

  That is, the present invention includes a step of obtaining a mixed solution by mixing a porous substance, carbon black and a solvent, a step of obtaining a mixed latex by mixing the mixed solution and a rubber latex, and a step of adding an acid to the mixed latex. The manufacturing method of the composite_body | complex containing these. In the manufacturing method according to the present invention, after the carbon black has entered the pores, the rubber latex is entered into the pores. Then, the mixed latex is coagulated in a state where the carbon black and the rubber latex are present in the pores. Thereby, it is possible to entangle rubber with carbon black existing in the pores. Since the composite obtained by the production method according to the present invention has such characteristics, it is a raw material for vulcanized rubber having excellent adhesion between the vulcanized rubber component and the porous material.

  The rubber latex is preferably natural rubber latex. Usually, since rubber latex contains water, the solvent preferably contains water, and the solvent is more preferably water.

  The average particle size of the porous material is preferably 1 mm or less, for example. When it is 1 mm or less, it is possible to obtain a composite that is a raw material of vulcanized rubber that is further excellent in adhesion between the vulcanized rubber component and the porous material.

  It is preferable that the mixed liquid forms a slurry. When the mixed liquid forms a slurry, a composite that is a raw material of the vulcanized rubber that is more excellent in adhesion between the vulcanized rubber component and the porous material can be obtained.

  The present invention also relates to a composite obtained by such a production method.

  The invention also relates to a rubber composition comprising such a composite. The rubber composition according to the present invention can be suitably used for a pneumatic tire. The present invention also relates to a pneumatic tire obtained using such a rubber composition.

[Production method of composite]
The method for producing a composite according to the present invention includes a step of obtaining a mixed solution by mixing a porous material, carbon black and a solvent, a step of obtaining a mixed latex by mixing the mixed solution and a rubber latex, and a mixed latex. Adding an acid.

  In the step of obtaining the mixed solution, the porous material, carbon black and solvent are mixed.

Examples of the porous material include fruit seeds, pumice, zeolite, and activated carbon. Of these, those having mesopores and those having macropores are preferable because carbon black can easily enter the pores. The average pore diameter of the mesopores is 2 nm or more, for example. The average pore diameter of the macropores is, for example, 50 nm or more. Moreover, a plant-derived material is preferable because it is environmentally friendly.
The average pore diameter can be measured by a mercury intrusion method.

The average particle diameter of the porous material is preferably 1 mm or less. On the other hand, the average particle size of the porous material is preferably 0.3 mm or more, more preferably 0.5 mm or more.
In addition, the average particle diameter of a porous substance is measured using the Shimadzu Corporation SALD-2200 laser diffraction type particle size distribution measuring device.

  As the carbon black, for example, conductive carbon black such as acetylene black and ketjen black can be used in addition to carbon black used in normal rubber industry such as SAF, ISAF, HAF, FEF, and GPF.

  As the solvent, a solvent containing water is preferable, and water is particularly preferable.

  In the step of obtaining the mixed latex, the mixed solution and the rubber latex are mixed.

  As rubber latex, natural rubber latex, synthetic rubber latex, etc. can be used, for example.

  As the natural rubber latex, for example, field latex, concentrated latex, ammonia latex and the like can be used. The number average molecular weight of the natural rubber in the natural rubber latex is preferably 2 million or more, for example. Examples of the synthetic rubber latex include styrene-butadiene rubber, butadiene rubber, nitrile rubber, and chloroprene rubber produced by emulsion polymerization.

  The mixed latex can be coagulated by the step of adding an acid to the mixed latex. Examples of the step of adding an acid to the mixed latex include a step of adding an acid while stirring the mixed latex. Examples of the acid include formic acid and sulfuric acid that are usually used for coagulation.

  The composite obtained by the step of adding an acid to the mixed latex contains a rubber component, a porous material, and carbon black.

  With respect to the obtained composite, the content of the porous material is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. On the other hand, the content of the porous material is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 2 parts by mass or less with respect to 100 parts by mass of the rubber component.

  With respect to the composite, the carbon black content is preferably 1 part by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. On the other hand, the carbon black content is preferably 45 parts by mass or less, more preferably 30 parts by mass or less, with respect to 100 parts by mass of the rubber component.

  The composite can be used, for example, as a master batch.

[Rubber composition]
The rubber composition according to the present invention is obtained by, for example, kneading a composite with a tackifier, a vulcanizing compound, stearic acid, zinc oxide, an anti-aging agent, oil, silica, a silane coupling agent, and the like. Can get.

  The rubber composition according to the present invention includes a composite. In addition to the composite, the rubber composition according to the present invention may contain a tackifier, a vulcanizing compound, stearic acid, zinc oxide, an anti-aging agent, oil, silica, a silane coupling agent, and the like.

  Examples of the vulcanizing compounding agent include vulcanizing agents such as sulfur and organic peroxides, vulcanization accelerators, vulcanization acceleration aids, vulcanization retarders and the like.

  Sulfur as the vulcanizing compounding agent may be normal sulfur for rubber. For example, powdered sulfur, precipitated sulfur, insoluble sulfur, highly dispersible sulfur and the like can be used. When the rubber physical properties and durability after vulcanization are taken into consideration, the sulfur content relative to 100 parts by mass of the rubber component is preferably 0.5 to 5.0 parts by mass in terms of sulfur content.

  As the vulcanization accelerator, sulfenamide vulcanization accelerator, thiuram vulcanization accelerator, thiazole vulcanization accelerator, thiourea vulcanization accelerator, guanidine vulcanization, which are usually used for rubber vulcanization. Examples thereof include accelerators and dithiocarbamate vulcanization accelerators. As for the compounding quantity of the vulcanization accelerator with respect to 100 mass parts of rubber components, 0.1-5.0 mass parts is preferable.

  The rubber composition according to the present invention can be suitably used for a pneumatic tire. Specifically, it can be suitably used as a raw material for a tire member of a pneumatic tire. More specifically, it can be suitably used as a raw material for treads and the like.

  The pneumatic tire according to the present invention includes, for example, a tire member obtained using such a rubber composition.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described.

[Additive]
The additives are shown below.
Natural rubber latex (Thai natural rubber latex)
Carbon black “DiaN220” (ISAF)
RSS # 3
Sulfur Shikoku Kasei Co., Ltd. (5% oil-treated sulfur)
Vulcanization accelerator “Noxeller CZ” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazolylsulfenamide)

  In Table 1, the amount of the additive compounded in the kneading step is shown as the number of parts by mass with respect to the solid content of natural rubber latex and the total of 100 parts by mass of RSS # 3.

[Preparation of fine materials]
The dried ume seeds were pulverized with a ball mill to obtain a pulverized product. The pulverized product was sieved to obtain a fine product having an average particle size of 0.5 mm to 1.0 mm.

[Preparation of kneaded product]
Example 1
A fine product, carbon black, and water were mixed according to the formulation shown in Table 1 to obtain a slurry. The slurry and natural rubber latex were mixed to obtain a rubber latex solution. A composite was obtained by adding formic acid to the rubber latex solution and coagulating it.
In accordance with the formulation described in Table 1, additives were blended into the composite and kneaded using a roll to obtain a kneaded product.

(Comparative Example 1)
Additives were blended according to the formulation described in Table 1, and kneaded using a roll to obtain a kneaded product.

(Comparative Examples 2-3)
In accordance with the formulation described in Table 1, fines and water were mixed to obtain a slurry. The slurry and natural rubber latex were mixed to obtain a rubber latex solution. The composite was obtained by adding formic acid to the rubber latex solution and coagulating it.
In accordance with the formulation described in Table 1, additives were blended into the composite and kneaded using a roll to obtain a kneaded product.

(Comparative Example 4)
According to the formulation described in Table 1, carbon black and water were mixed to obtain a slurry. The slurry and natural rubber latex were mixed to obtain a rubber latex solution. The composite was obtained by adding formic acid to the rubber latex solution and coagulating it.
In accordance with the formulation described in Table 1, additives were blended into the composite and kneaded using a roll to obtain a kneaded product.

[Evaluation]
Vulcanized rubber was obtained by vulcanizing the kneaded product at 150 ° C. for 30 minutes. About the vulcanized rubber, the adhesiveness of the fine material was evaluated based on the following evaluation conditions. The results are shown in Table 1.

(Adhesion of fine objects)
The vulcanized rubber was cut with a razor, and the cut surface was observed with a microscope (microscope with dial gauge manufactured by Nikon). The number of fine objects and the number of indentations were counted, and the residual ratio of the fine objects was determined by the following formula.
Residual rate = (number of fine objects) / (number of fine objects + number of indentations)
The case where the residual ratio was 70% or more was judged as ◯, the case where it was less than 70% and over 50% was judged as Δ, and the case where it was 50% or less was judged as ×.

  From Table 1, it can be seen that the vulcanized rubbers of Comparative Examples 1 and 4 obtained by mixing and kneading rubber and fine materials have a low residual rate of fine materials and weak adhesion. It can also be seen that the vulcanized rubber of Comparative Example 3 obtained by mixing and kneading a composite containing fines and not containing carbon black and carbon black is weak in adhesion.

  On the other hand, it can be seen that the vulcanized rubber of Example 1 has a high residual ratio of fines and is excellent in adhesiveness.

Claims (10)

A step of obtaining a mixed liquid by mixing a porous material, carbon black and a solvent;
A step of obtaining a mixed latex by mixing the mixed solution and rubber latex;
Adding an acid to the mixed latex,
In the step of obtaining the mixed liquid, the carbon black penetrates into the pores of the porous material.
A method for producing a composite. The manufacturing method of the composite_body | complex of Claim 1 whose average particle diameter of the said porous substance is 0.3 mm or more . The method for producing a composite according to claim 1 , wherein the rubber latex is natural rubber latex. The manufacturing method of the composite_body | complex in any one of Claims 1-3 in which the said solvent contains water. The average particle diameter of the said porous substance is 1 mm or less, The manufacturing method of the composite_body | complex in any one of Claims 1-4 . The manufacturing method of the composite_body | complex in any one of Claims 1-5 in which the said liquid mixture makes a slurry form. The composite_body | complex obtained by the manufacturing method in any one of Claims 1-6 .   A rubber composition comprising the composite according to claim 7.   The rubber composition according to claim 8 for tire use.   A pneumatic tire obtained using the rubber composition according to claim 8.