WO2016013573A1

WO2016013573A1 - Method for producing rubber composition, rubber composition, compound, and method for improving silica yield rate of rubber composition

Info

Publication number: WO2016013573A1
Application number: PCT/JP2015/070819
Authority: WO
Inventors: 西岡　利恭; 一富田; 皇雄三崎; 亮太上池
Original assignee: 日本エイアンドエル株式会社
Priority date: 2014-07-25
Filing date: 2015-07-22
Publication date: 2016-01-28
Also published as: TW201609983A; JP2017160278A

Abstract

Provided is a method for producing a rubber composition that includes a rubber latex (A) and silica particles (B), said method including a co-coagulation step in which the rubber latex (A) and silica particles (B) are brought into contact with a coagulant (D) to cause co-coagulation, wherein, at the same time as or prior to the time when the total quantity of the rubber latex (A), the total quantity of the silica particles (B), and the total quantity of the coagulant (D) finish being inserted into a starting material system that is made to co-coagulate, a portion or the total quantity of a water-soluble polymer compound (C) is inserted. Therein, in relation to 100 parts by weight (in terms of solid content) of the rubber latex (A), the amount of silica particles (B) used is 20-200 parts by weight (in terms of solid content), the amount of the water-soluble polymer compound (C) used is 0.05-10 parts by weight (in terms of solid content), and the amount of the coagulant (D) used is 10-50 parts by weight (in terms of solid content).

Description

Method for producing rubber composition, rubber composition, compound, and method for improving silica yield ratio in rubber composition

The present invention relates to a method for producing a rubber composition having a high silica yield ratio. The present invention also relates to a rubber composition obtained by the production method, a composition containing the rubber composition, and a method for improving the yield ratio of silica in the rubber composition.

For the purpose of improving the strength and wear resistance of various rubber materials, a rubber composition (hereinafter referred to as carbon dry masterbatch and abbreviated as C-DMB) in which solid rubber and carbon black particles are kneaded has been used for a long time. It has been used in various fields. Further, a rubber composition obtained by kneading solid rubber and silica particles (hereinafter referred to as silica dry masterbatch and abbreviated as Si-DMB) has long been widely known as a material having performance similar to that of C-DMB. It was.

In the early 1990s, tire manufacturers found that when Si-DMB was used for tire tread rubber, there was less energy loss and fuel savings. Since then, Si-DMB has been As a rubber composition with little loss, it has come to be widely used for tire tread rubber and power transmission rubber products that undergo repeated deformation.

However, since silica particles have a lower chemical affinity for solid rubber than carbon black particles, Si-DMB requires a great amount of time and power energy in the process of uniformly dispersing silica particles in the solid rubber, that is, the kneading process. There has been a strong need for a significant reduction.

As one means, instead of solid rubber, water-dispersible rubber latex such as synthetic rubber latex or natural rubber latex and water-dispersed slurry of silica particles are uniformly mixed in a liquid state in advance, and then acid or inorganic metal is mixed. A method has been proposed in which a rubber composition is produced by coagulating with a salt or the like and sequentially undergoing precipitation, dehydration, washing, and drying steps. The rubber composition produced by this method (hereinafter referred to as silica wet masterbatch and abbreviated as Si-WMB) is a technical concept well known from many prior arts since the 1970s.

For example, Patent Documents 1 to 12 disclose multifaceted technologies for Si-WMB, such as the properties of silica particles, the method of stirring an aqueous dispersion slurry of silica particles, the use of a silane coupling agent, and the type and usage of a salting-out agent. Information is disclosed.

However, the silica particle yield ratio in Si-WMB (ratio of the solid content weight of the silica particles remaining in the Si-WMB to the solid content weight of the blended silica particles is probably because the hydrophilicity of the silica particle surface is very strong. ) Is very low. In particular, Patent Document 11 describes that only a yield ratio as low as about 40% can be obtained unless the silica particles are previously treated with a silane coupling agent. In general, silane coupling agents are said to be expensive. For this reason, it is not clear, but to the best of our knowledge, Si-WMB is currently not mass-produced on a commercial basis. .

US Pat. No. 3,523,096 US Pat. No. 3,686,113 US Pat. No. 3,686,219 US Pat. No. 3,686,220 US Pat. No. 3,689,451 US Pat. No. 3,689,452 US Pat. No. 3,694,398 US Pat. No. 3,716,513 U.S. Pat. No. 3,840,382 US Patent No. 4002594 US Pat. No. 5,763,388 Japanese Patent No. 5220189

An object of the present invention is to provide a rubber composition having a high silica yield ratio and a method for producing the same. Moreover, the objective of this invention is providing the compound containing the said rubber composition. Furthermore, the objective of this invention is providing the yield ratio improvement method of the silica in a rubber composition.

The present invention relates to a method for producing a rubber composition comprising a rubber latex (A) and silica particles (B), wherein the rubber latex (A) and the silica particles (B) are contacted with a coagulant (D) and co-coagulated. At the same time as when the total amount of the rubber latex (A), the total amount of the silica particles (B) and the total amount of the coagulant (D) have been added to the raw material system to be co-coagulated or Before that, a part or all of the water-soluble polymer compound (C) is added, and the amount of silica particles (B) used is 20 to 200 with respect to 100 parts by weight (converted to solid content) of the rubber latex (A). Parts by weight (in terms of solid content), the amount of water-soluble polymer compound (C) used is 0.05 to 10 parts by weight (in terms of solids), and the amount of coagulant (D) used is 10 to 50 parts by weight (in terms of solids) A method for producing a rubber composition is provided.

In the co-coagulation step, the water-soluble polymer compound (C) and the coagulant (D) are mixed in advance before bringing the rubber latex (A) and the silica particles (B) into contact with the coagulant (D). The rubber latex (A) and the silica particles (B) are preferably contacted with the coagulant (D) in the presence of the conductive polymer compound (C).

The rubber latex (A) preferably contains an emulsion polymerization conjugated diene rubber latex. It is preferable that the water-soluble polymer compound (C) contains a polyalkylene oxide.

The present invention also provides a rubber composition that can be obtained by the above production method, and a compound containing the rubber composition.

Furthermore, the present invention is a method for improving the yield ratio of silica in a rubber composition containing a co-coagulated product of rubber latex (A) and silica particles (B), comprising rubber latex (A) and silica particles (B ) In contact with the coagulant (D) for co-coagulation, and in the co-coagulation step, the raw material system to be co-coagulated has a total amount of rubber latex (A), a total amount of silica particles (B) and a coagulant. At the same time or before the end of charging the total amount of (D), a part or all of the water-soluble polymer compound (C) is charged, and 100 parts by weight of rubber latex (A) (in terms of solid content), The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solids), the amount of water-soluble polymer compound (C) is 0.05 to 10 parts by weight (in terms of solids), and a coagulant ( D) is used in an amount of 10 to 50 parts by weight ( And solid content conversion), it provides a yield ratio improving method of the silica in the rubber composition.

According to the present invention, it is possible to provide a method for producing a rubber composition capable of obtaining a rubber composition having a high silica yield ratio. Moreover, according to this invention, the rubber composition with a high yield ratio of a silica, and the compound containing the said rubber composition can be provided. Furthermore, according to the present invention, a method for improving the yield ratio of silica in a rubber composition can be provided.

The method for producing a rubber composition according to this embodiment is a method for producing a rubber composition containing a rubber latex (A) and silica particles (B), wherein the rubber latex (A) and the silica particles (B) are coagulant. When contacting and co-coagulating with (D), the water-soluble polymer compound (C) is added until the total amount of the rubber latex (A) and the silica particles (B) is brought into contact with the coagulant (D). The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solid content) and 100 parts by weight (in terms of solid content) of rubber latex (A). ) Is used in an amount of 0.05 to 10 parts by weight (in terms of solid content) and the coagulant (D) is used in an amount of 10 to 50 parts by weight (in terms of solid content).

The rubber latex (A) may be an emulsion in which rubber polymer fine particles are stably dispersed in a solvent, and may further contain an emulsifier as necessary. Examples of the rubber latex (A) include emulsion polymerization conjugated diene rubber latex, natural rubber latex and modified latex thereof. Further, a solid rubber such as solution polymerized styrene-butadiene copolymer rubber, solution polymerized polybutadiene rubber, solution polymerized acrylonitrile-butadiene copolymer rubber is dissolved in a good solvent for each rubber, and then it is used with an emulsifier or a surfactant. The rubber latex etc. which were made into the forced emulsion in water are also mentioned, These can be used 1 type (s) or 2 or more types. Among these, the rubber latex (A) preferably contains an emulsion polymerization conjugated diene rubber latex.

As emulsion polymerization conjugated diene rubber latex, known polybutadiene emulsion polymer latex, styrene-butadiene emulsion copolymer latex, acrylonitrile-butadiene emulsion copolymer latex, styrene-butadiene-vinylpyridine emulsion copolymer latex. 1 type, or 2 or more types can be used. The emulsion polymerization conjugated diene rubber latex is particularly preferably a styrene-butadiene emulsion copolymer latex.

In addition, when obtaining an emulsion copolymer latex, it is possible to copolymerize a known copolymerizable monomer having a functional group in addition to styrene, butadiene, acrylonitrile, and vinylpyridine. Specific examples of such monomers include unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid, and unsaturated epoxy monomers such as anhydrides, glycidyl methacrylate, and allyl glycidyl ether. Body, hydroxyl-containing unsaturated monomers such as hydroxyethyl acrylate, hydroxyethyl methacrylate, etc., and one or more of each can be used.

The average particle size of the rubber-based polymer contained in the rubber latex (A) by the photon correlation method is preferably 10 nm to 200 nm, and more preferably 20 nm to 100 nm. The average particle diameter of rubber latex by photon correlation method should be adjusted by appropriately adjusting the various emulsifiers used in the polymerization of rubber latex, the type and amount of polymerization initiator used, the method of addition, the ratio of polymerization water used, etc. Is possible.

The silica particles (B) may be silica prepared by a wet method. As silica particles (B), an aqueous solution of sodium silicate, that is, a wet silica aqueous dispersion slurry produced by depositing silica particles by adding an acid to water glass or blowing carbon dioxide gas, a wet silica Silica water dispersion slurry in which silica powder obtained by drying from water dispersion slurry is dispersed in water again, and silica water dispersion slurry in which dry silica powder produced by a dry method is dispersed in water are mentioned. 1 type (s) or 2 or more types can be used.

The water-soluble polymer compound (C) is a compound having a viscosity average molecular weight of 100,000 to 20 million. The viscosity average molecular weight of the water-soluble polymer compound (C) is more preferably 500,000 to 15 million. Examples of the water-soluble polymer compound (C) include polyalkylene oxide, polyacrylamide, acrylamide-unsaturated carboxylate copolymer, alkali-soluble acrylic emulsion, and modified products thereof. Or two or more of them can be used. The water-soluble polymer compound (C) is preferably a polyalkylene oxide, polyacrylamide, or an acrylamide-unsaturated carboxylate copolymer. The water-soluble polymer compound (C) particularly preferably contains a polyalkylene oxide. The water-soluble polymer compound (C) is more preferably polyethylene oxide.

As the coagulant (D), acids such as mineral acid and acetic acid, alkali metals, alkaline earth metals, aluminum sulfates, chlorides and hydroxides can be used. Among these, sodium chloride, calcium chloride, and aluminum sulfate are preferable, and sodium chloride is more preferable.

In the production method of the present invention, rubber latex (A), silica particles (B), water-soluble polymer compound (C), and coagulant (D) are used, and 100 parts by weight (solid content) of rubber latex (A). The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solid content), and the amount of water-soluble polymer compound (C) used is 0.05 to 10 parts by weight (in terms of solids). The amount of the coagulant (D) used must be 10 to 50 parts by weight (in terms of solid content).

The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solids) and 30 to 190 parts by weight (in terms of solids) with respect to 100 parts by weight (in terms of solids) of rubber latex (A). It is preferably 50 to 180 parts by weight (in terms of solid content). If the silica particle (B) is less than 20 parts by weight (in terms of solid content), the substantial silica content is small, and if it exceeds 200 parts by weight (in terms of solid content), the yield of silica particles is poor.

The amount of the water-soluble polymer compound (C) used is 0.05 to 10 parts by weight (in terms of solid content) with respect to 100 parts by weight (in terms of solid content) of the rubber latex (A). It is preferably part by weight (in terms of solid content), more preferably 0.1 to 5 parts by weight (in terms of solid content). If the water-soluble polymer compound (C) is less than 0.05 parts by weight (in terms of solid content), the yield rate of silica particles is inferior, and even if it exceeds 10 parts by weight (in terms of solid content), the improvement in performance is small and added. It is difficult to obtain an effect commensurate with the amount.

The amount of the coagulant (D) used is 10 to 50 parts by weight (in terms of solids) and 100 to 45 parts by weight (in terms of solids) with respect to 100 parts by weight (in terms of solids) of the rubber latex (A). It is preferably 10 to 40 parts by weight (in terms of solid content), and more preferably. If the coagulant (D) is less than 10 parts by weight (in terms of solid content), the yield rate of silica particles is poor, and even if it exceeds 50 parts by weight (in terms of solid content), the improvement in performance is small and the effect commensurate with the amount added. Is difficult to obtain.

In the co-coagulation step, the water-soluble high concentration is added at the same time or before the end of charging the total amount of rubber latex (A), the total amount of silica particles (B) and the total amount of coagulant (D) into the raw material system to be co-coagulated. It is important to add part or all of the molecular compound (C).

In other words, in the co-coagulation step, the water-soluble polymer compound (at the same time or before the end of contacting the whole amount of the rubber latex (A), the whole amount of the silica particles (B) and the whole amount of the coagulant (D) ( Part or all of C) is brought into contact with at least one of rubber latex (A), silica particles (B) and coagulant (D).

In the co-coagulation step, when the rubber latex (A) and the silica particles (B) are brought into contact with the coagulant (D) and co-coagulated, the total amount of the rubber latex (A) and the silica particles (B) is coagulated. It can be said that the water-soluble polymer compound (C) is added before the contact with (D).

That is, in the production method of the present invention, the order of adding the rubber latex (A), the silica particles (B), the water-soluble polymer compound (C) and the coagulant (D), particularly the water-soluble polymer compound (C). The timing of putting in is important. According to the method for producing the rubber composition, it is not necessary to purify during the co-coagulation step, and a rubber composition having an excellent silica yield can be obtained in a short step.

Specific embodiments of adding rubber latex (A), silica particles (B), water-soluble polymer compound (C) and coagulant (D) include, for example,
(1) When the rubber latex (A) and the silica particles (B) are charged, then the water-soluble polymer compound (C) is charged, and finally the coagulant (D) is charged,
(2) When the rubber latex (A) and the silica particles (B) are charged and then the water-soluble polymer compound (C) is started, then the coagulant (D) is charged through another route.
(3) When the rubber latex (A) and the water-soluble polymer compound (C) are charged, the silica particles (B) are charged, and finally the coagulant (D) is charged.
(4) After adding the rubber latex (A) and the water-soluble polymer compound (C), and then starting to add the silica particles (B), when adding the coagulant (D) from another route,
(5) After introducing the silica particles (B) and the water-soluble polymer compound (C), the rubber latex (A) is added, and finally the coagulant (D) is added.
(6) After adding the silica latex (B) and the water-soluble polymer compound (C) and then starting to add the rubber latex (A), when adding the coagulant (D) from another route,
(7) After adding the water-soluble polymer compound (C), when the rubber latex (A) and silica particles (B) are added, and finally the coagulant (D) is added,
(8) After adding the water-soluble polymer compound (C) and then starting to add the rubber latex (A) and the silica particles (B), when adding the coagulant (D) from another route,
(9) After adding the silica particles (B), when adding the rubber latex (A) and the water-soluble polymer compound (C), and finally adding the coagulant (D),
(10) After adding the silica latex (B) and then starting to add the rubber latex (A) and the water-soluble polymer compound (C), then adding the coagulant (D) from another route,
(11) After introducing the rubber latex (A), when adding the silica particles (B) and the water-soluble polymer compound (C), and finally adding the coagulant (D),
(12) After adding the rubber latex (A) and then starting to add the silica particles (B) and the water-soluble polymer compound (C), when adding the coagulant (D) from another route,
(13) After charging the rubber latex (A) and the water-soluble polymer compound (C), the mixture of silica particles (B) and the coagulant (D) is charged.
(14) When the rubber latex (A) and the water-soluble polymer compound (C) are charged, and then the silica particles (B) are charged, the coagulant (D) is charged through another route.
(15) When the mixture of the rubber latex (A) and the coagulant (D) is charged after the silica particles (B) and the water-soluble polymer compound (C) are charged,
(16) When the silica particles (B) and the water-soluble polymer compound (C) are charged, and then the rubber latex (A) is charged at the same time, the coagulant (D) is charged through another route,
(17) When the mixture of the water-soluble polymer compound (C) and the coagulant (D) is charged after the rubber latex (A) and the silica particles (B) are charged,
(18) When the rubber latex (A) and the silica particles (B) are charged, and then the water-soluble polymer compound (C) is charged at the same time, the coagulant (D) is charged through another route, etc. Can be mentioned.

In the present invention, from the viewpoint of the yield rate of silica particles, when the rubber latex (A) and the silica particles (B) are brought into contact with the coagulant (D) and co-coagulated, the rubber latex (A) and the silica particles (B It is necessary to add the water-soluble polymer compound (C) until the total amount of) is brought into contact with the coagulant (D). Among these, it is more preferable to add the water-soluble polymer compound (C) to the coagulant (D) before bringing the rubber latex (A) and the silica particles (B) into contact with the coagulant (D). The co-coagulation step is preferably performed in water. By performing the co-coagulation step in water, the water-soluble polymer compound (C) can be dissolved in water and more uniformly mixed with other components.

In the present invention, there are no particular limitations on the conditions for co-coagulation, and the pH is generally 4 to 10 conditions, but it is preferable to co-coagulate at pH 5 to 9 from the viewpoint of the yield rate of silica particles, More preferably, it is co-coagulated at pH 6-8. The temperature is generally 0 to 99 ° C., but from the viewpoint of the yield rate of silica particles, co-coagulation is preferably performed at 5 to 80 ° C., preferably at 10 to 60 ° C. More preferably, it is co-solidified.

In the present invention, mixing can be performed using a known stirrer, mixer or the like.

The rubber composition of the present invention can be produced by co-coagulation followed by washing with water, dehydration, drying, etc., but these steps are not particularly limited and are generally used. Can be used. Moreover, it is preferable not to perform washing | cleaning in the manufacturing method of this invention from the point which can raise the yield rate of a silica further.

The rubber composition of the present invention is obtained by the method for producing a rubber composition of the present invention.

The rubber composition of the present invention can contain known additives. Known additives include vulcanizing agents, vulcanization accelerators, vulcanization acceleration aids, fillers, silane coupling agents, plasticizers, anti-aging agents, etc., and these may be used alone or as a mixture of two or more. Can be used as

Examples of the vulcanizing agent include organic sulfur-containing compounds such as sulfur, trimethylthiourea and N, N′-diethylthiourea.

Vulcanization accelerators include, for example, the trade name “Soccinol DM” (MBTS) manufactured by Sumitomo Chemical Co., Ltd., “Soccinol PX” (ZnEPDC) manufactured by the Company, “Soccinol PZ” (ZnMDC) manufactured by the Company, There are “Soccinol EZ” (ZnEDC), “Soccinol BZ” (ZnBDC), “Soccinol MZ” (ZnMBT), “Soccinol TT” (TMTD), etc.

Examples of the vulcanization acceleration aid include fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid, and metal oxides such as zinc white.

Examples of the filler include carbon black, kaolin clay, hard clay, calcium carbonate, barium sulfate, and diatomaceous earth.

Silane coupling agents include, for example, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, γ-glycidoxypropyltri Methoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ- Aminopropyltrimethoxysilane, bis- (3- (triethoxysilyl) propyl) tetrasulfide, bis- (3- (triethoxysilyl) propyl) disulfide, γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide, γ- Examples include trimethoxysilylpropylbenzothiazyl tetrasulfide.

Examples of the plasticizer include paraffinic oil, ester oil, and olefin oil.

Anti-aging agents include, for example, imidazoles such as 2-mercaptobenzimidazole, such as phenyl-α-naphthylamine, N, N′-di-β-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl- Examples include amines such as p-phenylenediamine, and phenols such as di-tert-butyl-p-cresol and styrenated phenol.

A compound obtained by further adding an additional rubber component to the rubber composition of the present invention is suitable for producing a tread rubber. That is, the present invention can also provide a tread rubber by appropriately molding a compound containing the above rubber composition and an additional rubber component (a compound for tread rubber).

The additional rubber component may be the same as or different from the rubber component derived from the rubber latex. The additional rubber component is not particularly limited. For example, natural rubber, polyisoprene rubber, emulsion polymerization styrene-butadiene copolymer rubber, solution polymerization random styrene-butadiene copolymer rubber, high transstyrene-butadiene copolymer rubber, low Cis polybutadiene rubber, high cis polybutadiene rubber, high trans polybutadiene rubber, styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, solution polymerization random styrene-butadiene-isoprene copolymer rubber, emulsion polymerization styrene-butadiene-isoprene copolymer Various diene rubbers such as block copolymers such as rubber, emulsion polymerization styrene-acrylonitrile-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, polystyrene-polybutadiene-polystyrene block copolymer Etc. The. These can be used alone or in combination of two or more.

In addition to the silica particles (B), an additional filler may be added to the tread rubber compound. Examples of the additional filler include carbon black.

The tread rubber compound includes various silane coupling agents, softeners, plasticizers, anti-aging agents, zinc white, stearic acid, vulcanizing agents, vulcanization accelerators, and the like that are commonly used in tread rubber compounds. Additives can also be blended.

The compound for tread rubber of the present invention is obtained by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. Unless otherwise specified,% and parts are based on weight.

(Measurement of polymerization conversion rate of rubber latex (A))
The reaction solution collected from the reaction vessel is weighed, dried at 150 ° C. for 1 hour, weighed again to measure the solid content, and can be calculated from the following equation.
Polymerization conversion rate (%) = [(solid content (g) −solid content other than monomer contained in reaction solution (g)) / amount of monomer component added to reaction system (g)] × 100

(Measurement of average particle diameter of rubber latex (A) by photon correlation method)
The average particle diameter of the obtained rubber latex (A) by the photon correlation method was measured. In the measurement, FPAR-1000 (manufactured by Otsuka Electronics) was used (JIS Z8826).

(Yield number of silica particles in the rubber composition, silica particle yield ratio)
The manufactured rubber composition is put in an empty platinum crucible and weighed, and then the platinum crucible is put in an electric furnace set at 800 ° C. and burned for 10 hours. After 10 hours, the platinum crucible is removed from the electric furnace and weighed again. The difference between the weight before combustion and the weight after combustion is the yield of latex in the rubber composition, and the weight after combustion is the yield of silica particles. From the following formula, the silica particles with respect to 100 parts by weight of the latex yield The number of yield parts (in terms of solid content) was calculated.
Yield part (parts by weight) of silica particles = (silica yield (g) / latex yield (g)) × 100
Next, the yield ratio of the silica particles was calculated from the following formula from the calculated number of parts of the silica particles (converted to solids) and the number of parts of the silica particles (converted to solids) with respect to 100 parts by weight of the rubber latex.
Silica particle yield ratio = (Yield part of silica particles (parts by weight) / Number of blended parts of silica particles (parts by weight))

(Manufacture of rubber latex (A))
In a pressure resistant polymerization reactor made of stainless steel, 200 parts by weight of pure water, 4.5 parts by weight of disproportionated potassium rosinate, 0.45 parts by weight of naphthalene sulfonic acid formalin condensate, 74 parts by weight of butadiene, 26 parts of styrene T-dodecyl mercaptan 0.2 part by weight, sodium triphosphate 0.65 part by weight, ethylenediaminetetraacetic acid 0.07 part by weight, sodium formaldehyde sulfoxylate 0.15 part by weight, paramentane hydroperoxide 0.10 Part by weight and 0.05 part by weight of ferrous sulfate heptahydrate were mixed and the polymerization reaction was started at 5 ° C. After confirming that the polymerization conversion reached 0.57 6 hours after the start of the polymerization, 0.5 parts by weight of diethylhydroxyamine was added 7 hours after the start of the polymerization to stop the polymerization reaction. The polymerization conversion rate when the reaction was stopped was 0.62. After removing the unreacted monomer by steam distillation, the solid content concentration was adjusted to 20.0% by weight with pure water to obtain a rubber latex (A).
The average particle diameter of the rubber latex (A) according to the photon correlation method was 60 nm.

(Silica particles (B))
Prepare 79 parts by weight of pure water in a stainless steel container equipped with a stirrer, add 21 parts by weight (containing about 5% by weight of water) of “Nipsil VN3” manufactured by Tosoh Corporation while stirring, and add silica water dispersion slurry (solid content) The concentration was 20.0% by weight).

(Water-soluble polymer compound (C))
1 part by weight of “PEO-8” manufactured by Sumitomo Seika Co., Ltd. was dissolved in 99 parts by weight of water to obtain a 1% by weight aqueous polyethylene oxide solution.

(Coagulant (D))
D-1: 10% by weight aqueous sodium chloride solution in which 10 parts by weight of sodium chloride was dissolved in 90 parts by weight of pure water.
D-2: 1% by weight calcium chloride aqueous solution in which 1 part by weight of calcium chloride is dissolved in 99 parts by weight of pure water.

(Manufacture of anti-aging emulsion water dispersion)
In a stainless steel container with a jacket set with a stirrer, put 76.3 parts by weight of styrenated phenol, 23.7 parts by weight of sodium dodecylbenzenesulfonate, and 160 parts by weight of pure water. The mixture was stirred for 30 minutes to emulsify and then cooled to room temperature to produce an aqueous dispersion of an antioxidant with a solid content concentration of 38.5% by weight.

(Manufacture of rubber composition)
Examples 1 to 4 and Comparative Examples 1 to 3
In the ratio shown in Table 1, the coagulant (D) adjusted to 25 ° C. was prepared in a stainless steel container with a stirrer, and the water-soluble polymer compound (C) was added and stirred. Thereto, an aqueous dispersion obtained by mixing rubber latex (A), silica particles (B), and an anti-aging emulsion water dispersion was added, stirred for 15 minutes, and co-coagulated to obtain a rubber composition. Thereafter, the obtained rubber composition was filtered through a 100-mesh stainless steel wire mesh and washed three times with 2500 parts by weight of 60 ° C. warm water with respect to 100 parts by weight of the rubber composition. The washed residue remaining on the mesh was dried at 110 ° C. for 6 hours. The number of silica yield parts and the silica yield ratio in the obtained rubber composition are shown together in Table 1.

Example 5
In the ratio shown in Table 1, the coagulant (D) and the water-soluble polymer compound (C) were mixed with an aqueous dispersion obtained by mixing the rubber latex (A), the silica particles (B), and the anti-aging emulsion water dispersion. The mixed aqueous solution was added, stirred for 15 minutes, and co-coagulated to obtain a rubber composition. Thereafter, it was washed and dried in the same manner as in Examples 1 to 4.

Comparative Example 4
An aqueous dispersion obtained by mixing rubber latex (A), silica particles (B) and an anti-aging emulsion emulsified aqueous dispersion at the ratio shown in Table 1 was added to the coagulant (D) and stirred for 15 minutes. Thereafter, the water-soluble polymer compound (C) was added, stirred for 15 minutes, and co-coagulated to obtain a rubber composition. Thereafter, it was washed and dried in the same manner as in Examples 1 to 4.

As is apparent from Table 1, in Examples 1 to 5 using the method for producing a rubber composition of the present invention, a rubber composition having a high silica yield ratio could be obtained.
Comparative Examples 1 to 3 did not contain the water-soluble polymer compound (C) and could not obtain a rubber composition having a high silica yield ratio. In Comparative Example 4, the water-soluble polymer compound (C) is added to the aqueous dispersion obtained by mixing the rubber latex (A), the silica particles (B), and the coagulant (D), and silica. A rubber composition with a high yield ratio could not be obtained.

As described above, since the rubber composition having a high silica yield ratio is obtained by the method for producing a rubber composition of the present invention, the workability is greatly improved in the production process of the rubber composition that requires compounding of silica particles. It can also contribute to the improvement and drastic reduction of the required power energy in the kneading process. That is, it is possible to provide a practical production technique of a rubber composition that is excellent in terms of environment and energy saving.

Claims

A method for producing a rubber composition comprising rubber latex (A) and silica particles (B),
A co-coagulation step of co-coagulating the rubber latex (A) and the silica particles (B) with the coagulant (D),
In the co-coagulation step, the water-soluble high concentration is obtained at the same time or before the end of charging the total amount of rubber latex (A), the total amount of silica particles (B) and the total amount of coagulant (D) into the raw material system to be co-coagulated. A part or all of the molecular compound (C) is charged,
The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solid content) and 100 parts by weight (in terms of solid content) of rubber latex (A), and the amount of water-soluble polymer compound (C) used. Is 0.05 to 10 parts by weight (in terms of solid content), and a method for producing a rubber composition, wherein the amount of the coagulant (D) used is from 10 to 50 parts by weight (in terms of solid content).
Before bringing the rubber latex (A) and the silica particles (B) into contact with the coagulant (D), the water-soluble polymer compound (C) and the coagulant (D) are mixed in advance, and the water-soluble polymer compound (C The method for producing a rubber composition according to claim 1, wherein the rubber latex (A) and the silica particles (B) are contacted with the coagulant (D) in the presence of.
The method for producing a rubber composition according to claim 1 or 2, wherein the rubber latex (A) comprises an emulsion polymerization conjugated diene rubber latex.
The method for producing a rubber composition according to any one of claims 1 to 3, wherein the water-soluble polymer compound (C) contains a polyalkylene oxide.
A rubber composition obtainable by the production method according to any one of claims 1 to 4.
A compound for tread rubber containing the rubber composition according to claim 5.
A method for improving the yield ratio of silica in a rubber composition comprising rubber latex (A) and silica particles (B),
A co-coagulation step of co-coagulating the rubber latex (A) and the silica particles (B) with the coagulant (D),
In the co-coagulation step, the water-soluble high concentration is obtained at the same time or before the end of charging the total amount of rubber latex (A), the total amount of silica particles (B) and the total amount of coagulant (D) into the raw material system to be co-coagulated. A part or all of the molecular compound (C) is charged,
The amount of silica particles (B) used is 20 to 200 parts by weight (in terms of solid content) with respect to 100 parts by weight (in terms of solid content) of rubber latex (A), and the amount of water-soluble polymer compound (C) used is A method for improving the yield ratio of silica in a rubber composition, wherein 0.05 to 10 parts by weight (in terms of solid content) and the amount of coagulant (D) used is 10 to 50 parts by weight (in terms of solid content).