JP7011460B2 - Masterbatch manufacturing method, rubber composition manufacturing method and tire manufacturing method - Google Patents

Description

The present disclosure relates to a method for producing a masterbatch, a method for producing a rubber composition, and a method for producing a tire.

Wet masterbatch with carbon black dispersed in natural rubber has higher Mooney viscosity than dry masterbatch. The wet masterbatch can be obtained, for example, by mixing natural rubber latex and carbon black slurry, coagulating and dehydrating. A dry masterbatch is a closed kneader such as a Banbury mixer, in which carbon black is kneaded into natural rubber.

Japanese Unexamined Patent Publication No. 2016-22618

In order to reduce the Mooney viscosity, it is conceivable to add a decomposing agent to the wet masterbatch when kneading with a closed kneader such as a Banbury mixer.

However, if a decoupling agent is added when kneading with a closed kneader, the low heat generation property deteriorates. It is considered that this is because the rubber molecular chain is broken before the decomposing agent is sufficiently dispersed, and the dispersal of the decomposing agent becomes poor. It is considered that the rubber molecular chains are broken before the desorbent is sufficiently dispersed because the rubber temperature rises sharply from the start of kneading in the closed kneader.

An object of the present disclosure is to provide a method for producing a masterbatch capable of lowering Mooney viscosity while maintaining low heat generation.

The method for producing a master batch in the present disclosure includes a step of coagulating a pre-coagulation rubber latex containing a filler to obtain a coagulated product and a step of dehydrating the coagulated product, and the step of dehydrating the coagulated product is a coagulated product. , Or to the coagulated product after dehydration, a mixture containing a rubber, a filler and a decoction agent is added, and the coagulant is dehydrated by an extruder.

It is a side view of the extruder used in Embodiment 1. FIG.

The method for producing a master batch according to the present disclosure includes a step of coagulating a pre-coagulation rubber latex containing a filler to obtain a coagulated product and a step of dehydrating the coagulated product, and the step of dehydrating the coagulated product includes a step of coagulating the coagulated product. , The coagulant, or the coagulant after dehydration, is added with a mixture containing rubber, a filler and a decoction agent, and is dehydrated by an extruder. The method for producing a masterbatch according to the present disclosure can include a step of mixing a filler slurry and a rubber latex in order to obtain a rubber latex before coagulation treatment.

The method for producing a masterbatch according to the present disclosure can reduce Mooney viscosity while maintaining low heat generation. This is because a mixture containing rubber, a filler and a decomposing agent is added to the coagulant and dehydrated by an extruder to disperse the decomposing agent in a state where the temperature of the rubber rises slowly. It is possible, and it is considered that this is because the dewatering agent can be dispersed before the rubber molecular chain is broken.

Further, the method for producing a masterbatch according to the present disclosure can effectively reduce Mooney viscosity. This is because the method for producing the masterbatch of the embodiment in the present disclosure can disperse the decomposing agent in a state where the temperature of the rubber rises slowly, so that the decomposing agent can be effectively dispersed. Conceivable. Therefore, the method for producing a masterbatch according to the present disclosure can effectively reduce Mooney viscosity.

The method for producing the rubber composition of the embodiment in the present disclosure includes the method for producing the masterbatch of the embodiment in the present disclosure. That is, the method for producing a rubber composition according to the present disclosure includes a step of coagulating a pre-coagulation rubber latex containing a filler to obtain a coagulant, a step of dehydrating the coagulant to obtain a master batch, and a master. Includes a step of kneading the batch and compounding agent.

The method for manufacturing a tire according to the present disclosure includes the method for manufacturing a masterbatch according to the present disclosure. That is, the method for manufacturing a tire according to the present disclosure includes a step of coagulating a pre-coagulation rubber latex containing a filler to obtain a coagulant, and a step of dehydrating the coagulant to obtain a master batch.

In the embodiments of the present disclosure, the filler can be an inorganic filler such as carbon black, silica, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide and the like. One or more of these can be selected and used.

Embodiment 1
Hereinafter, the first embodiment of the present disclosure will be described. The first embodiment uses carbon black as a filler for making a masterbatch.

The method for manufacturing a tire according to the first embodiment is a step of mixing a carbon black slurry and a rubber latex to obtain a rubber latex before solidification treatment, a step of coagulating the rubber latex before solidification treatment to obtain a solidified product, and a solidified product. A step of dehydrating to obtain a master batch, a step of kneading at least the master batch and the compounding agent to obtain a rubber mixture, a step of kneading a vulcanization-based compounding agent into the rubber mixture to obtain a rubber composition, and a rubber composition. It includes a step of vulcanizing and molding an unvulcanized tire made of a material.

The method for manufacturing a tire according to the first embodiment includes a step of mixing a carbon black slurry and a rubber latex to obtain a rubber latex before solidification treatment. In the carbon black slurry, carbon black is dispersed in water. The amount of carbon black in the carbon black slurry is preferably 1% by mass or more, more preferably 3% by mass or more, based on 100% by mass of the carbon black slurry. The upper limit of the amount of carbon black in the carbon black slurry is preferably 15% by mass, more preferably 10% by mass. The carbon black slurry can be obtained, for example, by mixing carbon black and water. As the carbon black, for example, carbon black such as SAF, ISAF, HAF, FEF, GPF, and conductive carbon black such as acetylene black and Ketjen black can be used. The carbon black may be granulated carbon black or ungranulated carbon black, which is granulated in consideration of its handleability. Carbon black and water can be mixed with a general disperser such as a high shear mixer, a homomixer, a ball mill, a bead mill, a high pressure homogenizer, an ultrasonic homogenizer, or a colloid mill. In the rubber latex for mixing with the carbon black slurry obtained by such a method, the rubber particles are dispersed in water in a colloidal manner. The rubber latex is, for example, a natural rubber latex, a synthetic rubber latex, or the like. The dry rubber content of the rubber latex to be mixed with the carbon black slurry is preferably 10% by mass or more, more preferably 20% by mass or more. The upper limit of the dry rubber content in the rubber latex is, for example, 60% by mass, preferably 40% by mass, and more preferably 30% by mass. The carbon black slurry and the rubber latex can be mixed by a general disperser such as a high shear mixer, a homomixer, a ball mill, a bead mill, a high pressure homogenizer, an ultrasonic homogenizer, and a colloid mill. In the rubber latex before the solidification treatment, rubber particles, carbon black and the like are dispersed in water. The pre-coagulation rubber latex may contain an anti-aging agent. On the other hand, no decoupling agent was added to the pre-coagulation rubber latex, and the pre-coagulation rubber latex did not contain the decoction agent.

The method for manufacturing a tire according to the first embodiment further includes a step of coagulating the rubber latex before the coagulation treatment to obtain a coagulated product. A coagulant can be added to the pre-coagulation rubber latex to cause coagulation. The coagulant is, for example, an acid. Examples of the acid include formic acid and sulfuric acid. Pre-coagulation The coagulated product obtained by coagulating the rubber latex contains water.

The method for manufacturing a tire according to the first embodiment further includes a step of dehydrating the coagulated product to obtain a masterbatch. In this step, a mixture (a mixture containing rubber, carbon black, and a decomposing agent) was added to the coagulated product, and the coagulated product after adding the mixture was dehydrated by an extruder 20 (see FIG. 1), and was dehydrated. , Includes molding the solidified product after the addition of the mixture. The water content of the dehydrated coagulated product after the addition of the mixture is preferably 15% or less, more preferably 10% by mass or less, still more preferably 5% by mass or less.

This step (the step of dehydrating the solidified product to obtain a masterbatch) includes adding a mixture to the solidified product and dehydrating the solidified product after adding the mixture with an extruder 20 (see FIG. 1). The mixture contains rubber, carbon black and a deliquescent. In the mixture, carbon black and a decomposing agent are dispersed in the rubber. The rubber is, for example, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and the like. The amount of natural rubber in the mixture is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 100% by mass, based on 100% by mass of rubber in the mixture. As the carbon black, for example, carbon black such as SAF, ISAF, HAF, FEF, GPF, and conductive carbon black such as acetylene black and Ketjen black can be used. The carbon black may be granulated carbon black or ungranulated carbon black, which is granulated in consideration of its handleability. The carbon black of the mixture is American Society for Testing and Materials (ASTM) and may belong to the same classification as the carbon black in the solidified product, or may belong to a different classification. The amount of carbon black in the mixture is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of rubber in the mixture. The amount of carbon black is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of rubber in the mixture. The deliquescent agent preferably contains 2,2'-dibenzamide diphenyl disulfide (DBD). The deafening agent preferably contains not only DBD but also a metal salt of fatty acid. The fatty acid constituting the metal salt of the fatty acid can be a saturated or unsaturated fatty acid having 6 to 28 carbon atoms, for example, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, linolenic acid. , Arakidic acid, behenic acid, nervonic acid and the like. Of these, saturated fatty acids having 14 to 20 carbon atoms are preferable. Examples of the metal constituting the metal salt of the fatty acid include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel and molybdenum. Of these, zinc is preferable. The amount of DBD in the decompression agent is preferably 5% by mass or more, more preferably 10% by mass or more, based on 100% by mass of the decompression agent. The upper limit of the amount of DBD is, for example, 30% by mass in 100% by mass of the decompression agent. The melting point of the deliquescent agent is preferably 50 ° C to 110 ° C. The amount of the deliquescent agent in the mixture can be, for example, 0.1 part by mass or more, or 0.5 part by mass or more, based on 100 parts by mass of the rubber in the mixture. The amount of the deliquescent agent can be, for example, 150 parts by mass or less, or 100 parts by mass or less, based on 100 parts by mass of the rubber in the mixture. In addition, instead of the decompression agent containing DBD, or in combination with the decoction agent containing DBD, another decoction agent may be used. Examples of such a chewy agent include zinc salts of 2-benzamidethiophenol, xylyl mercaptan, β-naphthyl mercaptan, pentachlorothiophenol (PCTP) and the like.

The mixture is a procedure similar to the above-mentioned procedure (specifically, a procedure including a step of mixing a carbon black slurry and a rubber latex to obtain a pre-coagulation rubber latex and a step of coagulating the pre-coagulation rubber latex. ) (Hereinafter referred to as "coagulant before addition of a rubber disintegrant") is dehydrated and kneaded with the coagulant to be produced. The composition of the coagulant before the addition of the decoction may be the same as or different from the composition of the coagulant (the coagulant to which the mixture is added) described above. An extruder 20 can be used, for example, to dehydrate the coagulated product before the addition of the decoction. A kneader can be used to knead the decoction and the coagulate before adding the decoction. Examples of the kneader include a closed kneader and an open roll. Banbury mixers, kneaders, etc. can be mentioned as closed kneaders.

As shown in FIG. 1, the extruder 20 for dehydrating the solidified product after adding the mixture is a single-screw extruder, and includes a screw 23 and an outer cylinder 27. A flow path (not shown) for a heating fluid is provided inside the screw 23. That is, the screw 23 includes a flow path for the heating fluid. Examples of the heating fluid include steam. The temperature of the heating fluid is preferably, for example, 100 ° C to 230 ° C. The extruder 20 can heat the coagulated product after adding the mixture not only by the rotation of the screw 23 but also by the heating fluid. The outer cylinder 27 includes a first outer cylinder 25 and a second outer cylinder 26. The second outer cylinder 26 is located downstream of the first outer cylinder 25. The first outer cylinder 25 is provided with a slit 24. The first outer cylinder 25 constitutes the first region 21 of the extruder 20. The second outer cylinder 26 constitutes the second region 22 of the extruder 20. The extruder 20 may further include a jacket 28. The extruder 20 has a supply port 29. The solidified product and the mixture may be charged separately into the extruder 20, or the solidified product and the mixture may be combined and charged into the extruder 20. The coagulated product after the addition of the mixture is dehydrated in the first region 21 and the second region 22 and discharged from the discharge port 30. As described above, the extruder 20 can dehydrate the coagulated product after the addition of the mixture by removing the water by heat and removing the water by pressing.

This step (step of dehydrating the coagulant to obtain a masterbatch) can include molding the coagulated product after addition of the mixture, which has been dehydrated by the extruder 20. The masterbatch thus obtained contains rubber, carbon black and deliquescent.

The masterbatch contains rubber. The rubber is, for example, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and the like. The amount of natural rubber in the masterbatch is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 100% by mass, based on 100% by mass of rubber.

The masterbatch contains rubber derived from the mixture. The amount of rubber derived from the mixture can be, for example, 40% by mass or less, 30% by mass or less, or 20% by mass or less, based on 100% by mass of rubber in the masterbatch. It can be 10% by mass or less. However, if the amount of rubber derived from the mixture is too large, the low heat generation tends to deteriorate. This is because the rubber derived from the mixture receives heat and shear due to kneading. On the other hand, the amount of rubber derived from the mixture can be, for example, 1% by mass or more, or 5% by mass or more, based on 100% by mass of rubber in the masterbatch.

The masterbatch also contains carbon black. The amount of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of rubber in the masterbatch. The amount of carbon black is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of rubber in the masterbatch.

The masterbatch also contains an antiseptic. The amount of the deliquescent agent is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and further preferably 0.1 part by mass or more with respect to 100 parts by mass of the rubber in the masterbatch. On the other hand, the amount of the deliquescent agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber in the masterbatch.

The method for manufacturing a tire according to the first embodiment includes a step of kneading a masterbatch and a compounding agent to obtain a rubber mixture. Examples of the compounding agent include a filler, zinc oxide, stearic acid, wax, an antiaging agent, and a silane coupling agent. One or more of these can be selected and kneaded with the masterbatch. The compounding agent added to the masterbatch in this step does not contain a frothing agent. Examples of the filler include carbon black, silica, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide and the like. Of these, silica is preferable. As anti-aging agents, aromatic amine-based anti-aging agents, amine-ketone anti-aging agents, monophenol anti-aging agents, bisphenol anti-aging agents, polyphenol anti-aging agents, dithiocarbamate anti-aging agents, thiourea anti-aging agents Anti-aging agents and the like can be mentioned. In this kneading step, other rubbers can be kneaded together with the masterbatch and the compounding agent. Examples of the rubber added to the master batch at the time of kneading include natural rubber, polyisoprene rubber, styrene-butadiene rubber, nitrile rubber, and chloroprene rubber. Kneading can be performed with a kneading machine. Examples of the kneader include a closed kneader and an open roll. Banbury mixers, kneaders, etc. can be mentioned as closed kneaders.

The method for manufacturing a tire according to the first embodiment further includes a step of kneading a vulcanization-based compounding agent into a rubber mixture to obtain a rubber composition. Examples of the vulcanization-based compounding agent include vulcanization agents such as sulfur and organic peroxides, vulcanization accelerators, vulcanization acceleration aids, and vulcanization retarders. Examples of sulfur include powdered sulfur, precipitated sulfur, insoluble sulfur, and highly dispersible sulfur. Sulfur amide-based vulcanization accelerator, thiuram-based vulcanization accelerator, thiazole-based vulcanization accelerator, thiourea-based vulcanization accelerator, guanidine-based vulcanization accelerator, dithiocarbamate-based vulcanization accelerator as vulcanization accelerators And so on.

The rubber composition comprises rubber derived from the masterbatch. The amount of rubber derived from the masterbatch can be, for example, 40% by mass or more, 60% by mass or more, and 80% by mass or more with respect to 100% by mass of rubber in the rubber composition. It can be, and it can be 100% by mass.

The rubber composition comprises carbon black. The amount of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of rubber in the rubber composition. The amount of carbon black is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of rubber in the rubber composition.

The rubber composition contains a deliquescent agent. The amount of the deliquescent agent is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and further preferably 0.1 part by mass or more with respect to 100 parts by mass of rubber in the rubber composition. .. On the other hand, the amount of the deliquescent agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of rubber in the rubber composition.

The rubber composition can further contain zinc oxide, stearic acid, wax, an antioxidant, sulfur, a vulcanization accelerator and the like. The amount of sulfur is preferably 0.5 part by mass to 5 parts by mass in terms of sulfur content with respect to 100 parts by mass of rubber in the rubber composition. The amount of the vulcanization accelerator is preferably 0.1 part by mass to 5 parts by mass with respect to 100 parts by mass of the rubber in the rubber composition.

The rubber composition can be used in the production of tires. Specifically, it can be used for manufacturing a tire member constituting a tire. For example, the rubber composition can be used to make tread rubber, sidewall rubber, chaher rubber, bead filler rubber and the like.

The method for manufacturing a tire according to the first embodiment includes a step of vulcanizing and molding an unvulcanized tire made of a rubber composition. The unvulcanized tire comprises a tire member made of a rubber composition. That is, the unvulcanized tire comprises a tire member containing a rubber composition. The tire obtained by the method of the first embodiment can be, for example, a pneumatic tire.

As described above, the method for producing a masterbatch in the first embodiment can reduce the Mooney viscosity while maintaining low heat generation. This is to disperse the decomposing agent in a state where the temperature rise of the rubber is gradual by adding a mixture containing rubber, carbon black and a decomposing agent to the coagulated product and dehydrating the mixture with the extruder 20. It is considered that this is possible because the dewatering agent can be dispersed before the rubber molecular chain is broken.

Modification 1
In the first embodiment, the mixture is added to the solidified product before being dehydrated by the extruder 20 and the mixture is dehydrated by the extruder 20, but in the modification 1 of the first embodiment, the solidified product is once delivered by the extruder 20. Alternatively, it is dehydrated multiple times, a mixture is added, and this is dehydrated by the extruder 20. In the first modification, a vacuum dryer, an air dryer, or the like may be used instead of the extruder 20 for dehydration before adding the mixture. In the first modification, since the water content of the coagulated product is reduced at the time when the mixture is added, heat and shear can be efficiently applied to the coagulated product after the mixture is added.

Modification 2
In the first embodiment, a mixture is added to the solidified product before it is dehydrated by the extruder 20, and this is dehydrated once by the extruder 20 and molded. However, in the second modification of the first embodiment, the extruder 20 is used. A mixture is added to the solidified product before dehydration, and the mixture is dehydrated a plurality of times (for example, twice) with an extruder 20 to be molded. In the second modification, a vacuum dryer, an air dryer, or the like may be used instead of the extruder 20 for this further dehydration, that is, the second and subsequent dehydrations.

Modification 3
In the first embodiment, in order to prepare a mixture, a wet step (specifically, a step of mixing a carbon black slurry and a rubber latex to obtain a rubber latex before solidification treatment and a step of solidifying the rubber latex before solidification treatment are performed. A coagulant before addition of a decoction agent is prepared by a method including), and the coagulant is kneaded with the coagulant. Add the rubber solution and knead.

Modification 4
In the first embodiment, the compounding agent added at the time of kneading the masterbatch does not contain the decomposing agent, but in the modified example 4 of the first embodiment, the compounding agent added at the time of kneading the masterbatch contains the decomposing agent. .. That is, in the modified example 4, a mixture (a mixture containing rubber, carbon black, and a decomposing agent) is added to the coagulated product to add a decoction agent, but further, a decoction agent is added at the time of kneading the masterbatch. do.

Modification 5
In the first embodiment, the carbon black and water are mixed in order to obtain the carbon black slurry, but in the modified example 5 of the first embodiment, instead of this operation, the carbon black and the rubber are mixed in order to obtain the carbon black slurry. It is mixed with latex (hereinafter, rubber latex for mixing with carbon black is referred to as "dilute rubber latex"). By mixing carbon black and dilute rubber latex, reaggregation of carbon black can be prevented. This is because it is considered that an ultrathin latex phase is formed on a part or all of the surface of the carbon black, and the latex phase suppresses the reaggregation of the carbon black. In dilute rubber latex, rubber particles are colloidally dispersed in water. The dilute rubber latex is, for example, a natural rubber latex, a synthetic rubber latex, or the like. The number average molecular weight of natural rubber in natural rubber latex is, for example, 2 million or more. The synthetic rubber latex is, for example, styrene-butadiene rubber latex, butadiene rubber latex, nitrile rubber latex, and chloroprene rubber latex. The dry rubber content of the dilute rubber latex is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.3% by mass or more. The upper limit of the dry rubber content is, for example, 5% by mass, preferably 2% by mass, and more preferably 1% by mass.

Of course, it is possible to select one or a plurality of these modifications and combine them with the first embodiment.

Hereinafter, examples of the present disclosure will be described.

The raw materials and chemicals are shown below.
Natural rubber latex (dry rubber content = 31.2% Mw = 232,000) Made by Golden Hope Coagulant Formic acid (1st grade 85%) Made by Nakaraitesk (10% solution diluted to pH 1.2, adjusted to pH 1.2, used)
N234 Carbon Black Tokai Carbon N134 Carbon Black Tokai Carbon N339 Carbon Black Tokai Carbon Shark Dissolving Agent A "Noctizer SD" (DBD and stearic acid mixture DBD content 25% by mass, melting point 54 ° C or higher) Ouchi Shinko Kagaku Kogyo Co., Ltd. Pushing Disinfectant B "Aktiplast MS" (mixture of DBD and fatty acid zinc DBD content 10% by mass Melting point 90 ° C to 100 ° C) Rhein Chemie Rheinau Shucking Dissolving Agent C "Structor A89" (DBD) Content 40% by mass Melt melting point 55 ℃) S & S Japan's Zinchua "No. 1 Zinchua" Mitsui Metals' stearate "Lunac S-20"Kao's anti-aging agent A "Nocrack 6C" Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent B "RD" Sulfur "powdered sulfur" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. Sulfurization accelerator A "Suncella CM" manufactured by Sanshin Kagaku Kogyo Co., Ltd. Silica "Nipseal AQ" manufactured by Shinko Kagaku Co., Ltd. Silane coupling agent "Si69" manufactured by Toso Silica Industry Co., Ltd.

Preparation of Mixture A Water was added to a natural rubber latex manufactured by Golden Hope at 25 ° C. to adjust the dry rubber content to 25% by mass. On the other hand, carbon black was added to water and stirred to obtain a carbon black slurry. The carbon black slurry was added to a natural rubber latex having a dry rubber content of 25% by mass according to Table 1, stirred, and a coagulant was added until the pH reached 4, to obtain a coagulated product. The coagulated product was dehydrated with a squeezer type uniaxial extrusion dehydrator (screw press V-02 type manufactured by Suehiro EPM). The decoction agent A was added to the coagulated product after dehydration according to Table 1, and the mixture was kneaded with a B-type Banbury mixer manufactured by Kobe Steel to obtain a mixture A.

Preparation of Mixture B A coagulant was obtained by the same procedure as the preparation of the coagulant in the mixture A. The coagulated product was dehydrated with a squeezer-type single-screw extruder. The coagulated product after dehydration was kneaded with a B-type Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture B.

Preparation of Masterbatch in Example 1 Water was added to a natural rubber latex manufactured by Golden Hope at 25 ° C. to adjust the dry rubber content to 25% by mass. On the other hand, carbon black was added to water and stirred to obtain a carbon black slurry. The carbon black slurry and the antiaging agent A were added to a natural rubber latex having a dry rubber content of 25% by mass according to Table 2, stirred, and the coagulant was added until the pH reached 4, to obtain a coagulated product. The coagulated product was first dehydrated with a squeezer-type single-screw extruder. Mixture A was added to the coagulated product after the primary dehydration according to Table 2, and the mixture was secondarily dehydrated by a squeezer type uniaxial extrusion dehydrator to obtain a masterbatch.

Preparation of Masterbatch in Example 2 Mixture A was added to the coagulated product prepared in the same procedure as in Example 1 according to Table 2, and this was first dehydrated by a squeezer type uniaxial extrusion dehydrator. This was secondarily dehydrated with a squeezer type single-screw extruder to obtain a masterbatch.

Preparation of Masterbatch in Example 3 Mixture A was added to the coagulated product prepared in the same procedure as in Example 1 according to Table 2, and this was dehydrated with a squeezer type uniaxial extrusion dehydrator to obtain a masterbatch.

Preparation of Masterbatch in Comparative Example 1 The coagulated product prepared in the same procedure as in Example 1 was primary dehydrated by a squeezer type uniaxial extrusion dehydrator. Mixture B was added to the coagulated product after the primary dehydration according to Table 2, and the mixture was secondarily dehydrated with a squeezer-type single-screw extruder to obtain a masterbatch.

Preparation of Masterbatch in Comparative Example 2 The coagulated product prepared in the same procedure as in Example 1 was primary dehydrated by a squeezer type uniaxial extrusion dehydrator. A concretion agent A was added to the coagulated product after the primary dehydration according to Table 2, and this was secondarily dehydrated with a squeezer type uniaxial extrusion dehydrator to obtain a masterbatch.

Preparation of Masterbatch in Comparative Example 3 The coagulated product prepared in the same procedure as in Example 1 was dehydrated with a squeezer type uniaxial extrusion dehydrator to obtain a masterbatch.

Preparation of unvulcanized rubber in each example Add a compounding agent excluding sulfur and vulcanization accelerator to the masterbatch according to Table 3, knead with a B-type Banbury mixer manufactured by Kobe Steel, and discharge the rubber mixture. did. The rubber mixture, sulfur and the vulcanization accelerator were kneaded with a B-type Banbury mixer to obtain unvulcanized rubber.

Loss tangent tanδ
The unvulcanized rubber was vulcanized at 150 ° C. for 30 minutes, and the heat generation property of the vulcanized rubber was evaluated by tan δ according to JIS K-6394. The tan δ was determined by a test using a UBM Leo spectrometer E4000 at 50 Hz, 80 ° C., and a dynamic strain of 2%. The tan δ of each example was displayed as an index with the tan δ of Comparative Example 1 as 100. The smaller the index, the lower the exothermic property and the better.

Mooney viscosity According to JIS K6300, using a rotary Mooney measuring machine manufactured by Toyo Seiki Seisakusho, the rubber mixture is preheated at 100 ° C. for 1 minute, then the rotor is rotated, and the torque value 4 minutes after the start of rotation is measured in Mooney units. Recorded. The Mooney viscosity of each example was displayed by an index with the Mooney viscosity of Comparative Example 1 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Although the difference between the vulcanized rubber tan δ in Example 1 and that in Comparative Example 1 was only 3 points, the Mooney viscosity of the rubber mixture in Example 1 was 19 points superior to that of Comparative Example 1. rice field.

The Mooney viscosity of the rubber mixture in Example 1 was 9 points better than that of Comparative Example 2.

The tan δ of the vulcanized rubber in Example 3 was 8 points superior to that of Comparative Example 3.

Unvulcanized rubber was prepared according to Tables 4 to 6. That is, a mixture C, a mixture D, and a mixture E were prepared according to Table 4, a masterbatch of each example was prepared according to Table 5, and unvulcanized rubber of each example was prepared according to Table 6.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an index with the tan δ of Example A as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example is expressed as an index with the Mooney viscosity of Example A as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Unvulcanized rubber was prepared according to Tables 7-9. That is, the mixture F and the mixture G were prepared according to Table 7, the masterbatch of each example was prepared according to Table 8, and the unvulcanized rubber of each example was prepared according to Table 9.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an index with the tan δ of Comparative Example 6 as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example was expressed as an index with the Mooney viscosity of Comparative Example 6 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Unvulcanized rubber was prepared according to Tables 10-12. That is, a mixture H and a mixture I were prepared according to Table 10, a masterbatch of each example was prepared according to Table 11, and unvulcanized rubber of each example was prepared according to Table 12.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an exponent with the tan δ of Comparative Example 8 as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example is expressed as an index with the Mooney viscosity of Comparative Example 8 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Unvulcanized rubber was prepared according to Tables 13 to 15. That is, a mixture J and a mixture K were prepared according to Table 13, a masterbatch of each example was prepared according to Table 14, and unvulcanized rubber of each example was prepared according to Table 15.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an exponent with the tan δ of Comparative Example 10 as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example is expressed as an index with the Mooney viscosity of Comparative Example 10 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Unvulcanized rubber was prepared according to Tables 16-18. That is, a mixture X and a mixture Y were prepared according to Table 16, a masterbatch of each example was prepared according to Table 17, and unvulcanized rubber of each example was prepared according to Table 18.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an index with the tan δ of Comparative Example 12 as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example was expressed as an index with the Mooney viscosity of Comparative Example 12 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Unvulcanized rubber was prepared according to Tables 19-21. That is, the mixture L and the mixture M were prepared according to Table 19, the masterbatch of each example was prepared according to Table 20, and the unvulcanized rubber of each example was prepared according to Table 21.

Tanδ and Mooney viscosity were measured by the methods already described. The tan δ of each example is expressed as an exponent with the tan δ of Comparative Example 14 as 100. The smaller the index, the lower the exothermic property and the better. On the other hand, the Mooney viscosity of each example is expressed as an index with the Mooney viscosity of Comparative Example 14 as 100. The smaller the index, the lower the Mooney viscosity and the better the workability.

Claims (3)

The process of coagulating the pre-coagulation rubber latex containing the filler to obtain a coagulated product,
Including the step of dehydrating the coagulated product.
The step of dehydrating the coagulated product comprises adding a mixture containing rubber, a filler and a frothing agent to the coagulated product or the coagulated product after dehydration, and dehydrating the coagulated product with an extruder.
How to make a masterbatch. A method for producing a rubber composition, which comprises a step of kneading the masterbatch obtained by the method for producing a masterbatch according to claim 1 and a compounding agent. A method for manufacturing a tire, which comprises the method for manufacturing a masterbatch according to claim 1.

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