JP2013159740A - Rubber composition for tire tread and pneumatic tire - Google Patents

Abstract

【選択図】なし[PROBLEMS] To improve low heat generation performance while maintaining rubber reinforcement.
SOLUTION: To 100 parts by mass of a diene rubber, 0.5 to 20 parts by mass of a compound represented by the following general formula (1), 30 to 120 parts by mass of silica, 5 to 60 parts by mass of carbon black, Is a rubber composition for tire treads. Moreover, it is a pneumatic tire which uses this rubber composition for a tread. In Formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an acryloyl group, a methacryloyl group, a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, a phenyl group, or 1 to 22 carbon atoms. An alkylphenyl group having the above alkyl group, A represents an alkylene group having 2 to 4 carbon atoms, and n represents a number of 4 to 90 indicating the average number of added moles of the oxyalkylene group.
[Chemical 1]

[Selection figure] None

Description

  The present invention relates to a rubber composition used for a tread of a pneumatic tire, and also relates to a pneumatic tire using the rubber composition.

  Conventionally, as a technique for improving the processability of a rubber composition for a tire tread, there is a method of adding process oil, a plasticizer, a processing aid or the like. However, these methods have problems such as deterioration of low heat generation performance and deterioration of steering stability performance and wear resistance performance due to a decrease in rubber reinforcement.

  In the following Patent Document 1, silica, a compound having one or more reactive groups for the rubber component and two or more adsorption groups for silica in the molecule, and a softener containing a specific oil are blended in the diene rubber. Thus, it is disclosed that wet performance is secured and steering stability performance is improved without increasing the viscosity of unvulcanized rubber and without impairing factory workability. As such compounds, those having a group derived from acrylic acid or methacrylic acid as a reactive group, a carboxyl group as an adsorbing group, and further having an oxyalkylene group are disclosed. Specifically, trimellitic acid is disclosed. Mono (2- (meth) acryloyloxyethyl) ester, polyoxyethylene glycerin trimaleate and the like are mentioned. The compounding of the compound in a rubber composition for tires is also disclosed in Patent Documents 2 to 5 below. The compound has a reactive group for the rubber component and an adsorbing group for silica, but does not disclose the point of blending the polyether compound unique to the present invention.

  On the other hand, the following Patent Document 6 relates to a technique for improving the temperature dependence of grip performance while satisfying rolling resistance performance and wear resistance performance, and a polyether system comprising at least two units of ethylene oxide and propylene oxide. It is disclosed that the temperature dependence of rubber hardness is improved by blending a copolymer. However, it does not disclose that the polyether compound unique to the present invention is blended.

  The following Patent Documents 7 and 8 disclose blending mono (meth) acrylates such as polypropylene glycol monomethacrylate and phenol EO-modified acrylate as processing aids with specific silica into diene rubber. Yes. However, these documents relate to a vibration-proof rubber composition, and the processing aid is blended for improving heat resistance (heat aging prevention effect), and does not suggest the present invention.

JP 2005-002295 A JP 2005-015691 A JP 2005-023144 A JP 2007-224195 A JP 2007-246627 A JP 2006-213864 A JP 2011-174034 A JP 2011-195807 A

  An object of the present invention is to provide a rubber composition for a tire tread capable of improving low heat generation performance while maintaining the reinforcing property of rubber, and a pneumatic tire using the same.

The rubber composition for a tire tread according to the present invention includes 0.5 to 20 parts by mass of a compound represented by the following general formula (1), 30 to 120 parts by mass of silica, and carbon with respect to 100 parts by mass of a diene rubber. And 5 to 60 parts by mass of black.

In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an acryloyl group, a methacryloyl group, a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, a phenyl group, or an alkyl group having 1 to 22 carbon atoms. A represents an alkylene group having 2 to 4 carbon atoms, and n represents a number of 4 to 90 indicating the average number of added moles of the oxyalkylene group.

  Moreover, the pneumatic tire according to the present invention is obtained by using the rubber composition in a tread.

  According to the present invention, by blending the specific polyether compound together with silica into the diene rubber, processability and low heat generation performance can be improved while maintaining rubber reinforcement.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  In the rubber composition according to the present embodiment, the diene rubber as the rubber component is not particularly limited. For example, natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR). ), Acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer, and the like. These diene rubbers may be used alone or in combination of two or more. The diene rubber is preferably a styrene butadiene rubber alone or a blend of styrene butadiene rubber and another diene rubber such as polybutadiene rubber. In the case of a blend, the styrene butadiene rubber is preferably 50% by mass or more in terms of the diene rubber component.

In the rubber composition according to this embodiment, a compound (polyether compound) represented by the following general formula (1) is blended as a processing aid.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, and an acrylate group or a methacrylate group represented by CH ₂ ═CR ¹ —COO— is a site that reacts with the diene rubber.

R ² is an acryloyl group (ie, CH ₂ ═CH—CO—), a methacryloyl group (ie, CH ₂ ═C (CH ₃ ) —CO—), a hydrogen atom, or a straight chain having 1 to 22 carbon atoms. Or a branched alkyl group (preferably an alkyl group having 1 to 18 carbon atoms), a phenyl group, or a linear or branched alkyl group having 1 to 22 carbon atoms (preferably an alkyl having 1 to 18 carbon atoms) An alkylphenyl group having a group).

  A represents an alkylene group having 2 to 4 carbon atoms. Therefore, the oxyalkylene group represented by AO is an oxyethylene group, an oxypropylene group or an oxybutylene group, preferably an oxyethylene group or an oxypropylene group, and a site that interacts with a silanol group (Si-OH) of silica. It becomes. These oxyalkylene groups may be composed of only one kind in one molecule, or two or more kinds may be combined. When two or more types are combined, a random type or a block type may be used. n is a number of 4 to 90 indicating the average number of added moles of the oxyalkylene group, preferably a number of 5 to 60, more preferably a number of 6 to 40, and even more preferably a number of 7 to 20. .

Specific examples of the polyether compound include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, poly (ethylene glycol / propylene glycol) -mono (meth) acrylate, polyethylene glycol / polypropylene glycol / mono (meta). ) Acrylate, poly (ethylene glycol tetramethylene glycol) -mono (meth) acrylate, poly (propylene glycol tetramethylene glycol) -mono (meth) acrylate and other polyalkylene glycol mono (meth) acrylates;
Polyalkylene glycol di (meth) acrylates such as polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate;
Alkoxy poly such as methoxypolyethylene glycol-mono (meth) acrylate, octoxypolyethyleneglycol / polypropyleneglycol-mono (meth) acrylate, lauroxypolyethyleneglycol-mono (meth) acrylate, stearoxypolyethyleneglycol-mono (meth) acrylate Alkylene glycol-mono (meth) acrylate;
Phenoxypolyalkylene glycol-mono (meth) acrylate such as phenoxypolyethylene glycol-mono (meth) acrylate, phenoxypolyethylene glycol / polypropylene glycol-mono (meth) acrylate;
Alkylphenoxypolyalkylene glycol-mono (meth) such as nonylphenoxypolyethylene glycol-mono (meth) acrylate, nonylphenoxypolypropylene glycol-mono (meth) acrylate, nonylphenoxypoly (ethylene glycol / propylene glycol) -mono (meth) acrylate Acrylate;
Etc. Any of these may be used alone or in combination of two or more. Here, (meth) acrylate indicates acrylate or methacrylate.

  The blending amount of the polyether compound is 0.5 to 20 parts by mass, preferably 1 to 20 parts by mass, more preferably 3 to 15 and even more preferably 100 parts by mass of the diene rubber. 3 to 10 parts by mass. If the blending amount of the polyether compound is small, the effect of the addition may not be sufficiently obtained. Conversely, if it is too large, the low heat generation performance may be impaired.

Silica used in the rubber composition according to this embodiment is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), and wet silica is preferable. Colloidal properties of the silica are not particularly limited, those which are nitrogen adsorption specific surface area (BET) 150~250m ² / g by BET method is preferably used, more preferably 180~230m ² / g. The BET of silica is measured according to the BET method described in ISO 5794.

  The compounding quantity of a silica is 30-120 mass parts with respect to 100 mass parts of diene rubbers, Preferably it is 30-100 mass parts, More preferably, it is 40-90 mass parts. If the blending amount of silica is less than 30 parts by mass, the effect of improving the low heat generation performance by blending with the polyether compound may be insufficient. On the other hand, if the amount of silica exceeds 120 parts by mass, the workability may be impaired.

  Carbon rubber can be blended with silica in the rubber composition according to the present embodiment. The carbon black is not particularly limited, and examples thereof include SAF, ISAF, HAF, and FEF. Preferably, SAF, ISAF, or HAF is used because of excellent wear resistance.

  The compounding quantity of carbon black is 5-60 mass parts with respect to 100 mass parts of diene rubbers, Preferably it is 10-40 mass parts. In the rubber composition according to the present embodiment, the filler is preferably composed mainly of silica. Therefore, it is preferable that 50% by mass or more of silica is included with respect to the total amount of filler composed of silica and carbon black.

  In order to further improve the dispersibility of silica, the rubber composition according to this embodiment preferably contains a silane coupling agent such as sulfide silane or mercaptosilane. Although the compounding quantity of a silane coupling agent is not specifically limited, It is preferable that it is 2-20 mass% with respect to a silica compounding quantity.

  The rubber composition according to the present embodiment is generally used in rubber compositions such as oil, zinc white, stearic acid, anti-aging agent, wax, vulcanizing agent, and vulcanization accelerator in addition to the above components. Various additives can be blended.

  Examples of the vulcanizing agent include sulfur and sulfur-containing compounds (for example, sulfur chloride, sulfur dichloride, polymer polysulfide, morpholine disulfide, and alkylphenol disulfide). Two or more types can be used in combination. Although the compounding quantity of a vulcanizing agent is not specifically limited, It is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of said diene rubbers, More preferably, it is 0.5-5 mass parts. is there.

  As said vulcanization accelerator, various vulcanization accelerators, such as a sulfenamide type | system | group, a thiuram type | system | group, a thiazole type | system | group, and a guanidine type | system | group, can be used, for example, any 1 type is used individually or in combination of 2 or more types. be able to. The blending amount of the vulcanization accelerator is not particularly limited, but is preferably 0.1 to 7 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the diene rubber. It is.

  The rubber composition according to the present embodiment can be prepared by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer. That is, in the first mixing stage, to the diene rubber, together with the polyether compound, silica and carbon black, other additives excluding the vulcanizing agent and the vulcanization accelerator are added and mixed, and then the obtained mixture In addition, a rubber composition can be prepared by adding and mixing a vulcanizing agent and a vulcanization accelerator in the final mixing stage.

  The rubber composition thus obtained is used as a rubber composition for a tread of a pneumatic tire, and is vulcanized at, for example, 140 to 200 ° C. according to a conventional method, whereby various tread rubbers for pneumatic tires are used. Can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Using a Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, in the first mixing stage, components other than sulfur and vulcanization accelerator are added and mixed (discharge temperature = 160 ° C.), and then obtained. In the final mixing stage, sulfur and a vulcanization accelerator were added to and mixed with the resulting mixture (discharge temperature = 90 ° C.) to prepare a tire tread rubber composition.

  In each rubber composition, 3 parts by weight of zinc white ("Zinc Hana 1" manufactured by Mitsui Kinzoku Mining Co., Ltd.) per 100 parts by mass of diene rubber (total amount of SBR and BR) as a common compound, Anti-aging agent (Sumitomo Chemical Co., Ltd. “Antigen 6C”) 2 parts by mass, stearic acid (Kao Co., Ltd. “Lunac S-20”) 2 parts by mass, wax (Nippon Seiki Co., Ltd. “OZOACE0355”) 2 Part by mass, 1.5 parts by mass of sulfur (“5% oil-filled fine powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.) and 1.8 parts by mass of a vulcanization accelerator (“Soccele CZ” manufactured by Sumitomo Chemical Co., Ltd.) were blended. .

  The details of each component in Table 1 are as follows.

SBR: Styrene butadiene rubber, “VSL5025-0HM” manufactured by LANXESS
・ BR: Polybutadiene rubber, “BR150B” manufactured by Ube Industries, Ltd.
Silica: “Nip Seal AQ” manufactured by Tosoh Silica Co., Ltd. (BET = 205 m ² / g)
Coupling agent: Sulfide silane coupling agent, “Si69” manufactured by Evonik Degussa
Carbon black: HAF, “Dia Black N341” manufactured by Mitsubishi Chemical Corporation
-Oil: "Extract No. 4 S" manufactured by Showa Shell Sekiyu KK

Polyether compound 1: manufactured by Lion Corporation, polyethylene glycol “PEG # 300”
Polyether compound 2: manufactured by Lion Corporation, polyoxyethylene polyoxypropylene monobutyl ether “Reosolve 703B”

Polyether compound 3: “Blemmer PE-90” manufactured by NOF Corporation, polyethylene glycol monomethacrylate (n = 2 in the following formula (2))
Polyether compound 4: “Blemmer PE-350” manufactured by NOF Corporation, polyethylene glycol monomethacrylate (n = 8 in the following formula (2))

Polyether compound 5: “Light Ester 9EG” manufactured by Kyoeisha Chemical Co., Ltd., polyethylene glycol dimethacrylate (n = 9 in the following formula (3))

Polyether compound 6: “Light Ester 041MA” manufactured by Kyoeisha Chemical Co., Ltd., methoxypolyethylene glycol methacrylate (n = 30 in the following formula (4))

Polyether compound 7: “Blemmer AE-400” manufactured by NOF Corporation, polyethylene glycol monoacrylate (n = 10 in the following formula (5))

Polyether compound 8: “Blemmer 70PEP-350B” manufactured by NOF Corporation, polyethylene glycol / polypropylene glycol / monomethacrylate (n1 = 5, n2 = 2, block type in the following formula (6))

Polyether compound 9: “Blenmer 55PET-800” manufactured by NOF Corporation, poly (ethylene glycol / tetramethylene glycol) -monomethacrylate (n1 = 10, n2 = 5, random type in the following formula (7))

Polyether compound 10: “Blenmer 50POEP-800B” manufactured by NOF Corporation, octoxypolyethylene glycol / polypropylene glycol / monomethacrylate (n1 = 8, n2 = 6, block type in the following formula (8))

Polyether compound 11: “Blemmer PSE-1300” manufactured by NOF Corporation, stearoxy polyethylene glycol-monomethacrylate (n = 30 in the following formula (9))

Polyether compound 12: “Blemmer 43PAPE-600B” manufactured by NOF Corporation, phenoxypolyethylene glycol / polypropylene glycol / monomethacrylate (n1 = 6, n2 = 6, block type in the following formula (10))

Polyether compound 13: “Blemmer ANP-300” manufactured by NOF Corporation, nonylphenoxypolypropylene glycol monoacrylate (n = 5 in the following formula (11))

  About each rubber composition, while evaluating workability, the hardness and the low heat generation performance were measured and evaluated using the test piece of the predetermined shape vulcanized | cured for 30 minutes at 150 degreeC. Each evaluation / measurement method is as follows.

・ Processability: In accordance with JIS K6300, using a rotorless Mooney measuring machine manufactured by Toyo Seiki Co., Ltd., preheated unvulcanized rubber at 100 ° C for 1 minute, and measured the torque value after 4 minutes in Mooney units for comparison. It was shown as an index with the value of Example 1 being 100. The smaller the index, the better the workability.

Hardness: Using a type A durometer in accordance with JIS K6253, the hardness at 23 ° C. was measured (test piece thickness = 13 mm), and the value of Comparative Example 1 was expressed as an index. A larger index means higher hardness and better reinforcement.

・ Low heat generation performance: Using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd., the loss factor tan δ was measured under the conditions of static strain 10%, dynamic strain ± 1%, frequency 10 Hz, temperature 60 ° C., comparative example The value was expressed as an index where the value of 1 was 100. The smaller the index is, the smaller tan δ is. Therefore, it means that heat generation is difficult and low heat generation performance is excellent.

  The results are as shown in Table 1. In Comparative Example 2 in which the amount of oil was increased as compared with Comparative Example 1 as a control, the low heat generation performance deteriorated, and the reinforcing property was impaired and the hardness was reduced. In Comparative Example 3 in which polyethylene glycol was blended as a processing aid and Comparative Example 4 in which polyoxyalkylene butyl ether was blended, although the processability was improved, the effect of improving the low heat generation performance was insufficient. Although polyethylene glycol monomethacrylate was used as a processing aid, in Comparative Example 5 in which the average number of moles of oxyethylene groups added was 2, the reinforcement was impaired. Although the polyether compound having a specific structure was used as a processing aid, the comparative example 6 with a small amount of the compound was insufficient in improving the low heat generation performance, and the comparative example 7 with a too large amount was reinforced. The effect of improving the low heat generation performance was impaired although it was excellent in performance.

  On the other hand, when it is Examples 1-12 which mix | blended the specified amount of the polyether compound with a specific structure as a processing aid, improving workability, maintaining or improving reinforcement (that is, hardness). At the same time, the low heat generation performance was remarkably improved. In Example 13, in which the amount of silica was increased compared to Example 2, a further improvement effect of the reinforcing property was obtained. Further, in Example 14 in which the amount of silica was reduced and the amount of carbon black was increased as compared with Example 2, a further improvement effect of workability was obtained.

Claims (2)

A tire containing 0.5 to 20 parts by mass of a compound represented by the following general formula (1), 30 to 120 parts by mass of silica, and 5 to 60 parts by mass of carbon black with respect to 100 parts by mass of the diene rubber. Tread rubber composition.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an acryloyl group, a methacryloyl group, a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, a phenyl group, or an alkyl having 1 to 22 carbon atoms. A represents an alkylphenyl group having a group, A represents an alkylene group having 2 to 4 carbon atoms, and different ones may be included in one molecule, and n represents an average added mole number of an oxyalkylene group. 90.)    A pneumatic tire using the rubber composition according to claim 1 as a tread.