WO2013047356A1

WO2013047356A1 - Rubber composition for tyre and pneumatic tyre using the same

Info

Publication number: WO2013047356A1
Application number: PCT/JP2012/074191
Authority: WO
Inventors: 三原　諭; 芦浦　誠; 直樹串田; 克典清水; 猛清原
Original assignee: 横浜ゴム株式会社
Priority date: 2011-09-30
Filing date: 2012-09-21
Publication date: 2013-04-04
Also published as: KR20140057651A; DE112012004088T5; CN104011128A; DE112012004088B9; DE112012004088B4; JP2013075977A; KR101604585B1; CN104011128B; JP5668660B2

Abstract

The purpose of the present invention is to provide a rubber composition for a tyre having superior workability whilst maintaining a 60ºC tanδ reduction effect, a manufacturing method for this rubber composition, and a pneumatic tyre using this rubber composition. The rubber composition of the present invention comprises a diene rubber including 30 to 90 wt% of one, two or more types of aromatic vinyl-conjugated diene copolymer having 20 to 40 wt% of 1,2-bonds in the conjugated diene. The total amount of 1,2-bonds is 10 to 55 wt% of the overall diene rubber. In the mixing step process for this rubber composition, 0.5 to 20 parts by weight silane coupling agent expressed by a specific formula and 20 to 120 parts by weight silica are mixed in per 100 parts by weight diene rubber. A vulcanising agent is not used in the mixing process, and the mixing temperature in the mixing process is less than 140ºC.

Description

Rubber composition for tire and pneumatic tire using the same

The present invention relates to a rubber composition for tires and a pneumatic tire using the same.

Conventionally, in the development of low rolling tires, by adding a mercapto silane coupling agent to diene rubber and silica, silica dispersibility is improved compared to conventional sulfur-containing silane coupling agents, and tan δ is greatly increased. Has been found to be reduced. However, because of the high reactivity of mercapto-based silane coupling agents, there is a problem of deterioration of workability (rapid scorching of rubber is fast) with increasing viscosity of the compound. When a mercapto silane coupling agent is used, the temperature at which the diene rubber, silica, mercapto silane coupling agent, etc. are mixed is generally 140 ° C. or higher (for example, Patent Document 1).

JP 2010-270247 A

When the mixing temperature at the time of mixing the conventional compound is less than 140 ° C., the reaction between the silica and the silane coupling agent and the dispersion of silica become insufficient, and the 60 ° C. tan δ increases.
Further, when a diene rubber, silica, mercapto silane coupling agent or the like is mixed at 140 ° C. or higher, the viscosity of the compound obtained generally increases. In this regard, the inventors of the present application have found that the generation of radicals during the compound mixing and the increase in the concentration cause the increase in the viscosity of the compound. The inventors of the present application have conceived that the viscosity of the compound can be reduced by trapping radicals in the compound.
Therefore, the present invention is excellent in workability while maintaining the 60 ° C. tan δ reduction effect (for example, a rubber composition for tires having a low viscosity of an unvulcanized compound and a smooth surface of an unvulcanized compound extrudate) An object of the present invention is to provide a pneumatic tire using the rubber composition for a tire, a manufacturing method thereof, and the tire.

As a result of diligent research to solve the above problems, the present inventor has found that the diene rubber is an aromatic vinyl-conjugated diene copolymer in which 1,2-bond in the conjugated diene is 20 to 40% by weight or Two or more kinds are included in an amount of 30 to 90% by weight, and the total amount of 1,2-bonds is 10 to 55% by weight based on the total amount of the diene rubber. Produced by a mixing step of mixing 0.5 to 20 parts by weight of the silane coupling agent and 20 to 120 parts by weight of silica, and without using a vulcanizing agent in the mixing step, the mixing temperature in the mixing step It was found that a tire rubber composition having a temperature of less than 140 ° C. can improve processability while maintaining a 60 ° C. tan δ reduction effect.
In addition, the inventors of the present application include 0.5 to 20 parts by weight of a silane coupling agent represented by a specific formula and 20 to 120 parts by weight of silica with respect to 100 parts by weight of the specific diene rubber. It is manufactured by a mixing step, and no vulcanizing agent is used in the mixing step. In the mixing step, [A] the mixing temperature is less than 140 ° C. and / or [B] 6,6-tetramethylpiperidine, dialkyldithiophosphate compound represented by a specific formula, thiodicarboxylic acid ester represented by a specific formula, phosphite compound represented by a specific formula, acrylate represented by a specific formula, specific And at least one radical trapping agent selected from the group consisting of a phenol compound and a lactone compound represented by the formula: According to the method for producing a rubber composition for a tire, which is 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber, radicals in the system are suppressed while maintaining a 60 ° C. tan δ reduction effect. The present inventors have found that a rubber composition for tires that can improve processability can be produced, and completed the present invention.
Conventional compounds with a composition that does not cause thickening of the compound even when the mixing temperature is high are used, and a high mixing temperature is applied to the compound having such a composition, so there is little possibility of causing poor mixing. It was.
On the other hand, in the present invention, mixing failure does not occur even at a mixing temperature of less than 140 ° C., which has been conventionally considered to cause mixing failure, is excellent in molding processability, and lowers 60 ° C. tan δ. It has been found a new compound that can be.

That is, the present invention provides the following 1 to 10.
1. The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which the 1,2-bond in the conjugated diene is 20 to 40% by weight, and the 1,2-bonds Is 10 to 55% by weight of the total amount of the diene rubber,
Produced by a mixing step in which 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica are mixed with 100 parts by weight of the diene rubber. A rubber composition for tires, wherein no vulcanizing agent is used in the mixing step, and the mixing temperature in the mixing step is less than 140 ° C.

[In the formula, at least one of R ¹¹ , R ¹² and R ¹³ is —O— (R ¹⁵ —O) _m —R ¹⁶ (R ¹⁵ is a divalent hydrocarbon group having 1 to 30 carbon atoms. R ¹⁶ is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and m is an integer of 1 to 30 , and the plurality of R ¹⁵ when R ¹⁵ is plural is may be the same or different.),
When one or two of R ¹¹ , R ^12, and R ¹³ are —O— (R ¹⁵ —O) _m —R ¹⁶ , the remaining group is an alkyl group having 1 to 12 carbon atoms, —O —R ¹⁷ (R ¹⁷ is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms.) , A hydrogen atom or an aryl group having 6 to 30 carbon atoms,
R ¹¹ , R ¹² and R ¹³ may be the same or different,
R ¹⁴ is a divalent hydrocarbon group having 1 to 30 carbon atoms. ]
2. In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the following formula (3), a formula (4) Using at least one radical trapping agent selected from the group consisting of a phosphite compound represented by the following formula, an acrylate represented by the following formula (5), a phenol compound represented by the following formula (6) and a lactone compound. 2. The rubber composition for tires according to 1 above, wherein the amount of the agent is 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber.

(In the formula (2), R ²¹ and R ²² are each independently an alkyl group having 1 to 18 carbon atoms, and n is 0 or 1. A plurality of R ²¹ and R ²² are the same, respectively. May be different.)

(In the formula (3), R ³¹ is .R ³² representing an alkylene group having 1 to 12 carbon atoms, R ³¹ and R ³² in. A plurality of an alkyl group having 1 to 30 carbon atoms, a respectively identical Or different.)

(In the formula (4), R ⁴¹ represents an alkoxy group having 1 to 4 carbon atoms. R ⁴² and R ⁴³ each independently represents an alkyl group having 1 to 4 carbon atoms. R ⁴⁴ represents hydrogen. .q representing the atom or an alkyl group having 1 to 4 carbon atoms is an integer of 0 or more, r is integer of 2 or more, q and r satisfy the relationship of q + r = 3. plurality of R ^42, R ⁴³ and R ⁴⁴ may be the same or different.)

(In formula (5), R ⁵¹ to R ⁵⁵ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.)

(In the formula (6), R ⁶¹ , R ⁶² and R ⁶³ each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom, and R ⁶¹ , R ⁶² and R ⁶³ (At least two of them represent a hydrocarbon group containing an alkyl group having 4 to 20 carbon atoms and optionally containing a hetero atom.)
3. 3. The rubber composition for tires according to 1 or 2 above, wherein one or more of the aromatic vinyl-conjugated diene copolymers have a hydroxyl group at the terminal.
4). 4. The tire use according to any one of 1 to 3, wherein a plasticizer is further used in the mixing step, and the amount of the plasticizer is 35 parts by weight or less with respect to 100 parts by weight of the diene rubber. Rubber composition.
5. After the mixing step, a glycol compound and / or a silane compound having an alkyl group is blended as a dispersion aid, and the amount of the dispersion aid is 0.5 to 5 parts by weight with respect to 100 parts by weight of the diene rubber. 5. The rubber composition for tires according to any one of 1 to 4 above, wherein
6). 6. The tire according to 5 above, wherein a plasticizer is further used in the mixing step, and the total amount of the dispersion aid and the plasticizer is 35 parts by weight or less with respect to 100 parts by weight of the diene rubber. Rubber composition.
7). Any one of the above 1 to 6, wherein the diene rubber further comprises at least one selected from the group consisting of an aromatic vinyl-conjugated diene copolymer having a 1,2-bond of less than 20% by weight, a butadiene rubber, and a natural rubber. The rubber composition for tires described in 1.
8). The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight, The total amount of bonds is 10 to 55% by weight in the total amount of the diene rubber,
Produced by a mixing step in which 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica are mixed with 100 parts by weight of the diene rubber. The manufacturing method of the rubber composition for tires which does not use a vulcanizing agent in a mixing process, and the mixing temperature in the said mixing process is less than 140 degreeC.

[In the formula, at least one of R ¹¹ , R ¹² and R ¹³ is —O— (R ¹⁵ —O) _m —R ¹⁶ (R ¹⁵ is a divalent hydrocarbon group having 1 to 30 carbon atoms. R ¹⁶ is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and m is an integer of 1 to 30 , and the plurality of R ¹⁵ when R ¹⁵ is plural is may be the same or different.),
When one or two of R ¹¹ , R ^12, and R ¹³ are —O— (R ¹⁵ —O) _m —R ¹⁶ , the remaining group is an alkyl group having 1 to 12 carbon atoms, —O —R ¹⁷ (R ¹⁷ is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms.) , A hydrogen atom or an aryl group having 6 to 30 carbon atoms,
R ¹¹ , R ¹² and R ¹³ may be the same or different,
R ¹⁴ is a divalent hydrocarbon group having 1 to 30 carbon atoms. ]
9. In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the following formula (3), a formula (4) ), A phosphite compound represented by the following formula (5), at least one radical trapping agent selected from the group consisting of a phenol compound and a lactone compound represented by the following formula (6). 9. The method for producing a tire rubber composition according to 8 above, wherein the amount of the trapping agent is 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber.

(In the formula (6), R ⁶¹ , R ⁶² and R ⁶³ each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom, and R ⁶¹ , R ⁶² and R ⁶³ (At least two of them represent a hydrocarbon group containing an alkyl group having 4 to 20 carbon atoms and optionally containing a hetero atom.)
10. A pneumatic tire using a tire rubber composition according to any one of 1 to 7 or a tire rubber composition manufactured by the method for manufacturing a tire rubber composition according to 8 or 9 as a tire tread.

The tire rubber composition of the present invention is excellent in workability while maintaining the 60 ° C. tan δ reduction effect. According to the method for producing a tire rubber composition of the present invention, it is possible to obtain a tire rubber composition having excellent processability while maintaining the 60 ° C. tan δ reduction effect. The pneumatic tire using the tire rubber composition of the present invention or the tire rubber composition obtained by the method for producing the tire rubber composition of the present invention has a high 60 ° C. tan δ reduction effect and excellent productivity.

FIG. 1 is a partial cross-sectional view in the tire meridian direction showing an example of an embodiment of a pneumatic tire using the rubber composition for a tire of the present invention.

The present invention will be described in detail below.
The rubber composition for tires of the present invention,
The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which the 1,2-bond in the conjugated diene is 20 to 40% by weight, and the 1,2-bonds Is 10 to 55% by weight of the total amount of the diene rubber,
Produced by a mixing step in which 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica are mixed with 100 parts by weight of the diene rubber. A tire rubber composition characterized in that no vulcanizing agent is used in the mixing step and the mixing temperature in the mixing step is less than 140 ° C.

[In the formula, at least one of R ¹¹ , R ¹² and R ¹³ is —O— (R ¹⁵ —O) _m —R ¹⁶ (R ¹⁵ is a divalent hydrocarbon group having 1 to 30 carbon atoms. R ¹⁶ is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and m is an integer of 1 to 30 , and the plurality of R ¹⁵ when R ¹⁵ is plural is may be the same or different.),
When one or two of R ¹¹ , R ^12, and R ¹³ are —O— (R ¹⁵ —O) _m —R ¹⁶ , the remaining group is an alkyl group having 1 to 12 carbon atoms, —O —R ¹⁷ (R ¹⁷ is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms.) , A hydrogen atom or an aryl group having 6 to 30 carbon atoms,
R ¹¹ , R ¹² and R ¹³ may be the same or different,
R ¹⁴ is a divalent hydrocarbon group having 1 to 30 carbon atoms. ]

<Diene rubber>
The diene rubber will be described below.
In the present invention, the diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight. , 2- The total amount of bonds is 10 to 55% by weight based on the total amount of the diene rubber, so that mixing failure does not occur even if the mixing temperature is low in the mixing step, and the generation of radicals is suppressed. An increase in viscosity is suppressed, processability is excellent, and 60 ° C. tan δ can be reduced.
The diene rubber used in the present invention contains one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight.
In the aromatic vinyl-conjugated diene copolymer contained in the diene rubber, the amount of 1,2-bond in the conjugated diene unit constituting the copolymer is 20 to 40% by weight of the copolymer. If there is no particular limitation.
The skeleton of the aromatic vinyl-conjugated diene copolymer can be constituted by a copolymer obtained by copolymerizing a conjugated diene monomer and an aromatic vinyl monomer. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. 1,3-pentadiene and the like. Examples of the aromatic vinyl monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert -Butylstyrene, divinylbenzene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethylstyrene, vinylpyridine and the like.
The skeleton of the aromatic vinyl-conjugated diene copolymer is preferably styrene butadiene rubber.
In the present invention, the amount of 1,2-bond in the conjugated diene unit constituting the aromatic vinyl-conjugated diene copolymer is reduced from 60 ° C. tan δ and excellent in workability, so that 20 -40% by weight, preferably 22-40% by weight, more preferably 25-40% by weight.

The aromatic vinyl-conjugated diene copolymer can further have a functional group such as a hydroxyl group, an alkoxysilyl group, and an amino group. The functional group can be attached to the end of the aromatic vinyl-conjugated diene copolymer and / or as a side chain. The functional group can be bonded directly or via a group to the backbone of the aromatic vinyl-conjugated diene copolymer. Examples of the group via the functional group and the skeleton of the aromatic vinyl-conjugated diene copolymer include an organic group such as a hydrocarbon group and polysiloxane.
The weight average molecular weight of the aromatic vinyl-conjugated diene copolymer is preferably 6.0 × 10 ⁵ to 15 × 10 ⁵ from the viewpoint of reduction of tan δ at 60 ° C. and workability, and 8.0 × 10 ^5. More preferably, it is ˜14 × 10 ⁵ . The weight average molecular weight (Mw) of the aromatic vinyl-conjugated diene copolymer is measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.
The aromatic vinyl-conjugated diene copolymers can be used alone or in combination of two or more. As the aromatic vinyl-conjugated diene copolymer, one or more kinds having a hydroxyl group at the terminal can be used. The aromatic vinyl-conjugated diene copolymer is not particularly limited for its production.

In the present invention, the amount of the aromatic vinyl-conjugated diene copolymer is 30 to 90% by weight, and 35 to 85% by weight based on the total amount of the diene rubber, from the viewpoint that 60 ° C. tan δ is reduced and processability is excellent. It is preferably 40 to 85% by weight.

In the present invention, the diene rubber may contain other diene rubber as a rubber component other than the aromatic vinyl-conjugated diene copolymer in which 1,2-bond in the conjugated diene is 20 to 40% by weight. . Examples of other diene rubbers include natural rubber, isoprene rubber, butadiene rubber, and aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is other than 20 to 40% by weight (for example, styrene butadiene rubber). And aromatic vinyl-conjugated diene copolymers having 1,2-bonds of less than 20% by weight or more than 40% by weight, butyl rubber, halogenated butyl rubber, and the like. From the viewpoint of reducing 60 ° C. tan δ and improving processability, natural rubber, butadiene rubber, and styrene-butadiene rubber having 1,2-bonds other than 20 to 40% by weight in the conjugated diene are preferable.
In the case where the other diene rubber is an aromatic vinyl-conjugated diene copolymer in which the 1,2-bond in the conjugated diene is other than 20 to 40% by weight, from the viewpoint that 60 ° C. tan δ is further reduced and processability is excellent. An aromatic vinyl-conjugated diene copolymer in which 1,2-bond in the conjugated diene is less than 20% by weight is preferable.
Other diene rubbers can be used alone or in combination of two or more.
The content of the other diene rubber is 60 ° C. tan δ when the other diene rubber is an aromatic vinyl-conjugated diene copolymer in which 1,2-bonds in the conjugated diene are other than 20 to 40% by weight. From the standpoint of further reduction and excellent workability, the total amount of diene rubber is preferably 15 to 55% by weight, more preferably 20 to 53% by weight.
The weight average molecular weight of the aromatic vinyl-conjugated diene copolymer with 1,2-bonds other than 20 to 40% by weight is preferably 6.0 × 10 ⁵ to 15 × 10 ⁵ , and 8.0 × 10 ^5. More preferably, it is ˜14 × 10 ⁵ .
The content of other diene rubbers is more excellent in workability by reducing 60 ° C. tan δ when the other diene rubber is other than an aromatic vinyl-conjugated diene copolymer (for example, butadiene rubber, natural rubber). In view of the above, the total amount of diene rubber is preferably 10 to 70% by weight, more preferably 10 to 65% by weight.

In the present invention, the total amount of 1,2-bonds is from 10 to 55% by weight, and from 15 to 55% by weight, based on the total amount of diene rubber, from the viewpoint that 60 ° C. tan δ is reduced and processability is excellent. It is preferably 20 to 55% by weight. The diene rubber further contains an aromatic vinyl-conjugated diene copolymer in which the 1,2-bond in the conjugated diene is other than 20 to 40% by weight, and / or the aromatic vinyl-conjugated diene copolymer. When a diene rubber having a 1,2-bond other than butadiene rubber (for example, butadiene rubber) is included, the amount of 1,2-bond is an aromatic vinyl in which the 1,2-bond in the conjugated diene is 20 to 40% by weight. -1,2-bonds possessed by conjugated diene copolymers, 1,2-bonds possessed by aromatic vinyl-conjugated diene copolymers other than 20-40% by weight of 1,2-bonds in conjugated dienes, and aromatics The total of 1,2-bonds possessed by a diene rubber having 1,2-bonds other than the aromatic vinyl-conjugated diene copolymer.

<Silane coupling agent>
The silane coupling agent will be described below. The silane coupling agent used in the present invention is a compound represented by the following formula (1) (mercapto group-containing silane coupling agent).

Examples of the divalent hydrocarbon group having 1 to 30 carbon atoms represented by R ¹⁴ and R ¹⁵ include an aliphatic hydrocarbon group such as an alkylene group (for example, a methylene group, a dimethylene group, and a trimethylene group); Group hydrocarbon groups; and combinations thereof.
Examples of the alkyl group having 1 to 30 carbon atoms, the alkenyl group having 2 to 30 carbon atoms, the aryl group having 6 to 30 carbon atoms, and the aralkyl group having 7 to 30 carbon atoms represented by R ¹⁶ and R ¹⁷ include, for example, Examples thereof include alkyl groups such as methyl group and ethyl group; alkenyl groups such as vinyl group and allyl group; aryl groups such as phenyl group and tolyl group; aralkyl groups such as benzyl group and phenethyl group.
m is preferably an integer of 1 to 30.
When one or two of R ¹¹ , R ¹² and R ¹³ are —O— (R ¹⁵ —O) _m —R ¹⁶ , the remaining group is an alkyl group having 1 to 12 carbon atoms, carbon Examples of the aryl group having 6 to 30 include an alkyl group such as a methyl group and an ethyl group; and an aryl group such as a phenyl group and a tolyl group.

The compound represented by the formula (1) is preferably a product name “VP Si363” of Degussa, from the viewpoint of further reducing tan δ at 60 ° C. and being excellent in workability. VP Si363 is represented by the following formula (1a).

In formula (1a), two of R ¹¹ , R ¹² and R ¹³ are —O— (C ₂ H ₄ —O) _n —C ₁₃ H ₂₇ and the rest are —O—C ₂ H ₅ . The average number of n is 5, and R ¹⁴ is a trimethylene group. The average content of —C ₂ H ₅ in —O—C ₂ H ₅ in R ¹¹ to R ¹³ is 33% or less.

The silane coupling agents can be used alone or in combination of two or more.
In the present invention, the amount of the silane coupling agent is 0.5 to 20 parts by weight with respect to 100 parts by weight of the diene rubber from the viewpoint of reducing 60 ° C. tan δ and excellent workability, and 1.0 to 18 parts by weight. Part is preferable, and 2.0 to 15 parts by weight is more preferable.

<Silica>
Silica will be described below. The silica used in the present invention is not particularly limited. Examples include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate and the like. Of these, precipitated silica is preferable from the viewpoint of reducing tan δ at 60 ° C. and improving workability. Silica can be used alone or in combination of two or more.
In the present invention, the amount of silica used in the mixing step is 20 to 120 parts by weight with respect to 100 parts by weight of the diene rubber from the viewpoint of reducing 60 ° C. tan δ and excellent workability, and 30 to 110 parts by weight. Part.

<Radical trapping agent>
In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the following formula (3), and the following formula (4): The phosphite compound shown, the acrylate shown by following formula (5), the phenol compound shown by following formula (6), and the at least 1 sort (s) of radical trap agent chosen from the group which consists of lactone compounds can be used. When a radical trapping agent is further used in the mixing step, 60 ° C. tan δ is further reduced, and the processability is excellent.

(Dialkyldithiophosphate compounds)

Examples of the alkyl group having 1 to 18 carbon atoms include a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, and a decyl group. When n is 0, two sulfur atoms can be directly bonded.

(2,2,6,6-tetramethylpiperidine)
2,2,6,6-tetramethylpiperidine is a compound represented by the following formula. 2,2,6,6-tetramethylpiperidine has a nitroxide free radical.

(Thiodicarboxylic acid ester)
The thiodicarboxylic acid ester used in the rubber composition for tires of the present invention is a compound represented by the following formula (3).

In the above formula (3), each R ³¹ independently represents an alkylene group having 1 to 12 carbon atoms. Among them, for the reason that the processability of the tire rubber composition of the present invention is further excellent, the carbon number is 1 It is preferably an alkylene group of ˜2. Specific examples of the alkylene group having 1 to 2 carbon atoms include an ethylene group. A plurality of R ³¹ may be the same or different.
In the above formula (3), R ³² represents an alkyl group having 1 to 30 carbon atoms. Among them, the alkyl group having 1 to 24 carbon atoms is preferred because the processability of the rubber composition for tires of the present invention is further improved. It is preferably an alkyl group having 6 to 24 carbon atoms, more preferably an alkyl group having 6 to 18 carbon atoms, and still more preferably an alkyl group having 8 to 18 carbon atoms. An alkyl group having 12 to 18 carbon atoms is particularly preferable, and an alkyl group having 12 to 14 carbon atoms is most preferable. Specific examples of the alkyl group having 12 to 18 carbon atoms include dodecyl group, hexadecyl group, tetradecyl group, octadecyl group and the like. A plurality of R ³² may be the same or different.

Preferred examples of the thiodicarboxylic acid ester include, for example, 3,3′-thiobispropionic acid dioctyl ester, 3,3′-thiobispropionic acid didecyl ester, and 3,3′-thiobispropionic acid didodecyl ester. Esters, 3,3′-thiobispropionic acid ditetradecyl ester, 3,3′-thiobispropionic acid dihexadecyl ester, 3,3′-thiobispropionic acid dioctadecyl ester, among others, Since the processability of the rubber composition for tires of the present invention is further excellent and 60 ° C. tan δ is further reduced, 3,3′-thiobispropionic acid didodecyl ester, 3,3′-thiobispropionic acid diester Tetradecyl ester, 3,3′-thiobispropionic acid dihexadecyl ester, 3,3′-thiobisp Preferably acid dioctadecyl ester, 3,3'-thio-bis acid didodecyl ester, 3,3'-thiobis propionic acid di tetradecyl ester is more preferable.

(Phosphite compound)
The phosphite compound used for the tire rubber composition of the present invention is a compound represented by the following formula (4).

In the above formula (4), R ⁴¹ represents an alkoxy group having 1 to 4 carbon atoms, and among them, it is an ethoxy group or a propoxy group because the processability of the tire rubber composition of the present invention is further excellent. Is preferable, and an ethoxy group is more preferable.
In the above formula (4), R ⁴² and R ⁴³ each independently represents an alkyl group having 1 to 4 carbon atoms, and among them, the processability of the tire rubber composition of the present invention is further excellent. A propyl group or a butyl group is preferable, and a tert-butyl group is more preferable. A plurality of R ⁴² and R ⁴³ may be the same or different.
In the above formula (4), R ⁴⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Among them, for the reason that the processability of the tire rubber composition of the present invention is further excellent, a hydrogen atom or a methyl group is preferable. A plurality of R ⁴⁴ may be the same or different.
In the above formula (4), q represents an integer of 0 or more, r represents an integer of 2 or more, and among them, the processability of the tire rubber composition of the present invention is further improved, and 60 ° C. tan δ is further increased. For reasons of reduction, it is preferable that q is 0 and r is 3. q and r satisfy the relation of q + r = 3.

As a preferred embodiment of the phosphite compound, for example, at least one of R ⁴² and R ^{43 in} the formula (4) is a tert-butyl group, and at least one of the plurality of R ⁴⁴ is a hydrogen atom or Examples of the compound are methyl groups, and specific examples thereof include tris (2,4-di-tert-butylphenyl) phosphite, bis (2,4-di-tert-butyl-6-methylphenyl) ethylphosphine. For example, fights.

(Acrylate)
The acrylate used in the tire rubber composition of the present invention is an acrylate represented by the following formula (5).

In the above formula (5), R ⁵¹ represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms (eg, methyl group, ethyl group, tert-butyl group, 1,1-dimethylpropyl group). Among them, the processability of the rubber composition for tires of the present invention is more excellent, and the straight chain or branched alkyl group having 1 to 6 carbon atoms is preferable because 60 ° C. tan δ is further reduced. And a methyl group is more preferable.
In the above formula (5), R ⁵² and R ⁵⁵ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms (for example, methyl group, ethyl group, tert-butyl group) Among these, the processability of the rubber composition for tires of the present invention is further excellent, and 60 ° C. tan δ is further reduced. A chain or branched alkyl group is preferable, a branched alkyl group having 1 to 6 carbon atoms is more preferable, a tert-butyl group or a 1,1-dimethylpropyl group is more preferable, and a 1,1-dimethylpropyl group is more preferable. Particularly preferred.
In the above formula (5), R ⁵³ and R ⁵⁴ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a tert-butyl group) Among these, the processability of the rubber composition for tires of the present invention is further excellent, and 60 ° C. tan δ is further reduced. A chain or branched alkyl group is preferable, a branched alkyl group having 1 to 6 carbon atoms is more preferable, and a 1,1-dimethylpropyl group is more preferable.

Preferred examples of the acrylate include a compound in which, in the above formula (5), R ⁵¹ is a hydrogen atom, R ⁵² and R ⁵⁵ are tert-butyl groups, R ⁵³ and R ⁵⁴ are methyl groups, and In the formula (5), examples include compounds in which R ⁵¹ is a methyl group and R ⁵² , R ⁵³ , R ⁵⁴ and R ⁵⁵ are 1,1-dimethylpropyl groups. In the above formula (5), R ⁵¹ is a methyl group, and R ⁵² , R ⁵³ , R ⁵⁴ and R ⁵⁵ are 1,1-dimethylpropyl. Compounds that are groups are preferred.

(Phenol compound)
The phenolic compound used in the tire rubber composition of the present invention is a compound represented by the following formula (6).

In the above formula (6), R ⁶¹ , R ⁶² and R ⁶³ each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom. Specific examples of the hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom include a methyl group, an ethyl group, a propyl group, an alkyl group having 4 to 20 carbon atoms described later, an octylthiomethyl group, and dodecylthio. A methyl group etc. are mentioned.
In addition, at least two of R ⁶¹ , R ⁶² and R ⁶³ represent a hydrocarbon group containing an alkyl group having 4 to 20 carbon atoms and optionally containing a hetero atom.
Here, the hydrocarbon group containing an alkyl group may be the alkyl group having 4 to 20 carbon atoms.
Specific examples of the alkyl group having 4 to 20 carbon atoms include butyl group (n-butyl group, sec-butyl group, isobutyl group, tert-butyl group), pentyl group, heptyl group, octyl group, dodecyl group, octadecyl group. Etc.

At least one of the above R ⁶¹ , R ⁶² and R ⁶³ is more excellent in processability of the tire rubber composition of the present invention, and moreover, because of the further reduction of 60 ° C. tan δ, a hetero atom (nitrogen atom, oxygen A hydrocarbon group containing an atom, phosphorus atom, sulfur atom, etc.), more preferably a group selected from the group consisting of groups represented by the following formulas (7) to (9): More preferably, it is a group represented by (7).

When at least one of R ⁶¹ , R ⁶² and R ⁶³ is a hydrocarbon group containing a hetero atom (nitrogen atom, oxygen atom, phosphorus atom, sulfur atom, etc.), the unpaired electron of the hetero atom and the silane cup Interaction with the polyether chain of the ring agent (above —O— (R ¹⁵ —O) _m —R ¹⁶ ) results in suppression of the interaction between the phenolic compound and silica, improving the dispersibility of silica. It is estimated that 60 ° C. tan δ is further reduced.
Moreover, it is estimated that the said hetero atom acts on the phenolic hydroxyl group of a phenol compound, the radical stabilization ability of a phenol compound improves, and workability further improves.

In the above formula (7), R ⁷¹ represents a linear alkylene group having 1 to 3 carbon atoms, and is preferably an ethylene group.
In the above formula (7), R ⁷² represents a linear or branched alkyl group having 4 to 18 carbon atoms, preferably an alkyl group having 12 or more carbon atoms.
In the above formula (7), * represents a bonding position.

In the above formula (8), R ⁸¹ represents a linear or branched alkyl group having 4 to 8 carbon atoms, and among them, an alkyl group having 6 or more carbon atoms is preferable. A plurality of R ⁸¹ may be the same or different.
In the above formula (8), * represents a bonding position.

In the above formula (9), R ⁹¹ represents a linear alkylene group having 1 to 4 carbon atoms, and is preferably a methylene group.
In the above formula (9), R ⁹² represents a linear or branched alkyl group having 4 to 12 carbon atoms, and among them, the processability of the tire rubber composition of the present invention is further improved. From the reason that 60 ° C. tan δ is further reduced, an alkyl group having 8 to 12 carbon atoms is preferable, and an alkyl group having 8 to 10 carbon atoms is more preferable.
In the above formula (9), * represents a bonding position.

Specific examples of the compound represented by the above formula (6) include 2,6-di-tert-butyl-p-cresol, isooctyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate. , Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,4-bis (octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino)- 1,3,5-triazine, 4,6-bis (dodecylthiomethyl) -o-cresol, 4,6-bis (octylthiomethyl) -o-cresol and the like, among which octadecyl-3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,4-bis (octylthio) -6- (4-hydroxy-3,5 Di-tert-butylanilino) -1,3,5-triazine, 4,6-bis (dodecylthiomethyl) -o-cresol, 4,6-bis (octylthiomethyl) -o-cresol are preferred, and octadecyl-3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate is more preferred.

(Lactone compound)
The lactone compound used for the tire rubber composition of the present invention is not particularly limited as long as it is a compound having a lactone structure. Here, the lactone structure refers to a cyclic structure having a carboxylic acid ester bond —C (═O) —O— in the ring.

As a first preferred embodiment of the lactone compound, a compound represented by the following formula (10) can be mentioned.

In the above formula (10), R ¹⁰¹ and R ¹⁰² each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, and the processability of the tire rubber composition of the present invention Is preferable, and a hydrogen atom is preferable because 60 ° C. tan δ is further reduced. A plurality of R ¹⁰¹ and R ¹⁰² may be the same or different.
In the above formula (10), m represents an integer of 1 to 3, and is preferably 2 for the reason that the processability of the tire rubber composition of the present invention is further excellent and 60 ° C. tan δ is further reduced. .

A second preferred embodiment of the lactone compound includes a compound represented by the following formula (11).

In the above formula (11), R ¹¹¹ represents a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, and the processability of the tire rubber composition of the present invention is further improved. For the reason that tan δ is further reduced, it is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 7 carbon atoms. A plurality of R ¹²¹ may be the same or different.
In the above formula (11), n represents an integer of 1 to 3.

The amount of the radical trapping agent is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber, from the viewpoint of further reducing 60 ° C. tan δ and being excellent in workability. More preferred are parts by weight.

Further plasticizers can be used in the mixing step. When a plasticizer is further used in the mixing step, the processability is superior. The plasticizer is not particularly limited. Examples thereof include petroleum mineral oil, coal tar mineral oil, fatty oil vegetable oil, phenol aldehyde resin, dioctyl phthalate, polyester, dioctyl sebacate, and terpene resin. The plasticizer may be previously added to a diene rubber (for example, an aromatic vinyl-conjugated diene copolymer).
The amount of the plasticizer is preferably 35 parts by weight or less, more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the diene rubber from the viewpoint of further reducing 60 ° C. tan δ and improving workability. preferable.
As will be described later, when a dispersion aid is used after the mixing step, the total amount of the dispersion aid and the plasticizer is reduced to 60 ° C. tan δ, and is excellent in workability. The amount is preferably 35 parts by weight or less, more preferably 10 to 35 parts by weight.

In the present invention, at least a diene rubber, a silane coupling agent represented by the formula (1), and silica are mixed in the mixing step.
The mixing temperature in the mixing step is less than 140 ° C., preferably 120 to 138 ° C., and preferably 125 to 135 ° C. from the viewpoint of suppressing generation of radicals, reducing 60 ° C. tan δ and excellent workability. Is more preferable.
No vulcanizing agent and / or vulcanization accelerator or vulcanization aid is used in the mixing step. When a vulcanizing agent, a vulcanization accelerator, and a vulcanization aid are used in the mixing step, the total amount of the vulcanization agent, the vulcanization accelerator, and the vulcanization aid is more excellent in workability by reducing 60 ° C. tan δ. In view of the above, the amount is preferably 2 parts by weight or less based on 100 parts by weight of the diene rubber.
The mixing method in the mixing step is not particularly limited. For example, the compound can be produced by kneading using a kneader such as a hermetic mixer, roll, or internal mixer.
The tire rubber composition of the present invention is produced by a mixing process. In the present invention, the compound produced in the mixing step (mixing first step) is used, and then, if necessary, a mixing second step of adding a dispersion aid, a vulcanizing agent and / or a vulcanizing agent. It is possible to set a third mixing step in which an auxiliary agent or a vulcanization auxiliary agent is added.

In the present invention, when setting the second mixing step using a dispersion aid after the mixing step (first mixing step), the dispersion aid is not particularly limited as long as it is generally used in a rubber composition. . Examples include glycol compounds, silane compounds having an alkyl group, and polysiloxane compounds.
The dispersion aid is preferably a glycol compound and / or a silane compound having an alkyl group from the viewpoint of further reducing 60 ° C. tan δ and improving workability.
Examples of the glycol compound include ethylene glycol, diethylene glycol, propylene glycol, and polypropylene glycol.
Examples of the silane compound having an alkyl group include compounds having one or more alkyl groups on one silicon atom. The alkyl group may have 1 to 18 carbon atoms. The silane compound can have 1 to 3 alkoxy groups in addition to the alkyl group. Specific examples include alkyltrialkoxysilanes such as octyltriethoxysilane and octyltrimethoxysilane; dialkyldialkoxysilanes; trialkylalkoxysilanes.
The amount of the dispersion aid is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the diene rubber from the viewpoint of further reducing 60 ° C. tan δ and being excellent in workability. More preferably.

The mixing temperature in the second mixing step is preferably less than 140 ° C.
The mixing method in the second mixing step is not particularly limited. A known rubber kneading machine such as a Banbury mixer, a kneader, or a roll can be used.

In the present invention, when the third mixing step is set after the mixing step (first mixing step) or after the second mixing step, the vulcanizing agent, vulcanization accelerator, and vulcanization aid used in the third mixing step. The agent is not particularly limited as long as it is generally used in rubber compositions. For example, a conventionally well-known thing is mentioned.
The amount of the vulcanizing agent (for example, sulfur) is preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the diene rubber.

The mixing temperature in the third mixing step is preferably less than 140 ° C.
The mixing method in the third mixing step is not particularly limited. A known rubber kneading machine such as a Banbury mixer, a kneader, or a roll can be used.

The tire rubber composition of the present invention may further contain a filler other than silica. Examples of fillers other than silica include carbon black, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, and titanium oxide.

The rubber composition for tires of the present invention may further contain an additive as long as the effect and purpose are not impaired. As additives, for example, silane coupling agents other than formula (1), anti-aging agents, processing aids, liquid polymers, terpene resins, thermosetting resins and the like are generally used for tire rubber compositions. And various compounding agents. The additive can be kneaded by a general method to form a rubber composition, which can be used for vulcanization or crosslinking. As long as the amount of the additive is not contrary to the object of the present invention, a conventional general amount can be used.

The conditions for vulcanizing the tire rubber composition of the present invention are not particularly limited.
The tire rubber composition of the present invention or the tire rubber composition produced by the method for producing a tire rubber composition of the present invention described later can be suitably used for a pneumatic tire (for example, a tire tread). .

Next, the manufacturing method of the rubber composition for tires of this invention is demonstrated below.
The method for producing the tire rubber composition of the present invention comprises:
The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight, The total amount of bonds is 10 to 55% by weight in the total amount of the diene rubber,
Produced by a mixing step in which 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica are mixed with 100 parts by weight of the diene rubber. It is a manufacturing method of the rubber composition for tires which does not use a vulcanizing agent in a mixing process, and the mixing temperature in the said mixing process is less than 140 ° C.

The tire rubber composition of the present invention can be produced by the method for producing a tire rubber composition of the present invention.
The components used in the method for producing a tire rubber composition of the present invention are the same as those of the tire rubber composition of the present invention.
In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the above formula (3), the above formula (4) A phosphite compound represented by formula (5), an acrylate represented by formula (5), a phenol compound represented by formula (6) and at least one radical trapping agent selected from the group consisting of the lactone compounds. It is preferable to do this. When a radical trapping agent is further used in the mixing step, 60 ° C. tan δ is further reduced, and the processability is excellent.

The radical trapping agent and the amount thereof are the same as described above.
In the method for producing a rubber composition for a tire of the present invention, the mixing temperature in the mixing step is less than 140 ° C. as described above. From the viewpoint of further reducing 60 ° C. tan δ and improving workability, it is preferably 120 to 140 ° C.
When the radical trapping agent is 2,2,6,6-tetramethylpiperidine, the mixing temperature is preferably 120 to less than 140 ° C.
When the radical trapping agent is a dialkyldithiophosphate compound represented by the formula (2), the mixing temperature is preferably 120 to 140 ° C. or less.

The pneumatic tire of the present invention will be described below. The pneumatic tire of the present invention is a pneumatic tire using, as a tire tread, the tire rubber composition of the present invention or the tire rubber composition manufactured by the manufacturing method of the tire rubber composition of the present invention.
The pneumatic tire of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an example of an embodiment of a pneumatic tire using a tire rubber composition. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion.

In FIG. 1, two carcass layers 4 in which reinforcing cords extending in the tire radial direction are arranged at predetermined intervals in the tire circumferential direction between left and right bead portions 3 and embedded in a rubber layer are extended. The part is folded back from the inner side in the tire axial direction so as to sandwich the bead filler 6 around the bead core 5 embedded in the bead part 3. An inner liner layer 7 is disposed inside the carcass layer 4. On the outer peripheral side of the carcass layer 4 of the tread portion 1, two belt layers 8 in which reinforcing cords inclined and extending in the tire circumferential direction are arranged at predetermined intervals in the tire axial direction and embedded in the rubber layer are arranged. It is installed. The reinforcing cords of the two belt layers 8 intersect each other with the inclination directions with respect to the tire circumferential direction being opposite to each other. A belt cover layer 9 is disposed on the outer peripheral side of the belt layer 8. A tread portion 1 is formed of a tread rubber layer 12 on the outer peripheral side of the belt cover layer 9. The tread rubber layer 12 is composed of the rubber composition for tires of the present invention. A side rubber layer 13 is disposed outside the carcass layer 4 of each sidewall portion 2, and a rim cushion rubber layer 14 is provided outside the folded portion of the carcass layer 4 of each bead portion 3.

The pneumatic tire of the present invention is not particularly limited except that the tire rubber composition of the present invention or the tire rubber composition produced by the method for producing a tire rubber composition of the present invention is used for a tread of a pneumatic tire. For example, it can be produced according to a conventionally known method. Moreover, as gas with which a tire is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<Manufacture of rubber composition for tire>
The components shown in the first step of each table are used in the amounts (parts by weight) shown in the same table, and these are kneaded for 6 minutes at the mixing temperature shown in each table with a closed mixer and released. The rubber composition for tires (unvulcanized) was prepared by adding the components shown in the mixing second step and the mixing third step in the amounts (parts by weight) shown in the table and kneading them with an open roll.
The first mixing step corresponds to the mixing step in the present invention.
The mixing temperature in the second mixing step in Tables 1 and 2 was 130 ° C, and the mixing temperature in the third mixing step in Tables 1 and 2 was 130 ° C. The mixing temperature in the second mixing step in Tables 3 and 4 was 130 ° C, and the mixing temperature in the third mixing step in Tables 3 and 4 was 130 ° C. The mixing temperature in the second mixing step in Tables 5 and 6 was 130 ° C., and the mixing temperature in the third mixing step in Tables 5 and 6 was 110 ° C.
<Manufacture of vulcanized rubber samples>
The tire rubber composition obtained as described above was press vulcanized at 160 ° C. for 20 minutes in a mold having a predetermined shape to produce a vulcanized rubber sample.

<Evaluation>
Using the unvulcanized rubber composition for tires obtained as described above, the extrusion processability, relative radical concentration, and Mooney viscosity were evaluated by the following methods. Further, tan δ at 60 ° C. was measured by the following method using the vulcanized rubber sample obtained as described above. The results are shown in each table.
Regarding the results of the relative radical concentration and tan δ at 60 ° C., Tables 1 and 2 are evaluated with reference to Standard Example 1, Tables 3 and 4 are evaluated with reference to Standard Example 2, and 5, 6, 7 The table was evaluated with reference to Standard Example 3.
Extrusion workability The surface condition of the extrudate was visually evaluated based on ASTM D2230. The evaluation criteria are the following five-step evaluation, and 4 or more are allowed.
5 = extrudable; 4 = extrudable; 3 = not extrudable; 2 = not extrudable and the surface of the extrudate is poor; 1 = not extrudable and the surface of the extrudate is very bad

Relative radical concentration The free radical concentration in the unvulcanized rubber was measured using a free radical monitor JES-FR30EX manufactured by JEOL. An unvulcanized rubber sample (5 mm width × 30 mm length × 1 mm thickness) was set in a sample tube and measured under the condition of 20 ° C. The measurement results obtained here include both carbon and sulfur radicals. As an ESR marker, Mn ²⁺ thermally diffused in MgO was used. The radical concentration in each sample was expressed as a relative area (index) when the peak area of the Mn (manganese) marker was 100. The larger the index, the higher the radical concentration of rubber.

-Mooney viscosity It measured at 100 degreeC based on JISK6300. The lower the index, the better the workability.
・ Tan δ at 60 ℃
Using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho, the initial strain was 10%, the amplitude was ± 2%, and the frequency was 20 Hz. The lower the index, the better the rolling resistance.

The details of each component shown in Tables 1 and 2 are as follows.
SBR1: 20 parts by weight of styrene butadiene rubber added to 100 parts by weight of SBR, 60% by weight of Vn (1,2-bond) in SBR, OH-modified, weight average molecular weight 9.3 × 10 ⁵ , Nipol NS530 manufactured by Nippon Zeon
SBR2: Styrene butadiene rubber oiled 37.5 parts by weight with respect to 100 parts by weight of SBR, 43% by weight of Vn (1,2-bond) in SBR, OH-modified, weight average molecular weight 12.6 × 10 ⁵ , E581 manufactured by Asahi Kasei Corporation
SBR3: Styrene butadiene rubber oiled 25 parts by weight with respect to 100 parts by weight of SBR, 33% by weight of Vn (1,2-bond) in SBR, OH-modified, weight average molecular weight 13.3 × 10 ⁵ , Nipol NS570 manufactured by Nippon Zeon
SBR4: Styrene butadiene rubber oiled 37.5 parts by weight with respect to 100 parts by weight of SBR, 10% by weight of Vn (1,2-bond) in SBR, no OH modification, weight average molecular weight 6.3 × 10 ⁵ , Toughden 1534 manufactured by Asahi Kasei Corporation
SBR6: Styrene butadiene rubber oiled with 37.5 parts by weight with respect to 100 parts by weight of SBR, 71.5% by weight of Vn (1,2-bond) in SBR, weight average molecular weight of 7.8 × 10 ⁵ , LANXESS brand name BUNA VSL5025-HM1
BR: butadiene rubber, 1% by weight of Vn (1,2-bond amount) in BR, no OH modification, weight average molecular weight 5.0 × 10 ⁵ , Nipol 1220 manufactured by Zeon Corporation
Silica 1: “Zeosil 1165MP” manufactured by Rhodia
・ Silane coupling agent 1: sulfide silane coupling agent, Si69VP manufactured by Degussa
Silane coupling agent 2: VP Si363 manufactured by Degussa
・ Zinc flower: Zinc oxide, manufactured by Shodo Chemical Industry Co., Ltd., "Zinc oxide 3 types"
・ Stearic acid: manufactured by Nippon Fats and Oil
Anti-aging agent: “6PPD”, manufactured by Flexis
-Oil: Showa Shell Sekiyu KK "Extract No. 4 S"
・ Dispersing aid 1: “Zyethylene glycol” manufactured by Maruzen Petrochemical Co., Ltd.
-Dispersing aid 2: "Octyltriethoxysilane" manufactured by Shin-Etsu Chemical Co., Ltd.
・ Sulfur: manufactured by Tsurumi Chemical Industry Co., Ltd.
・ Vulcanization accelerator 1: “Noxeller CZ-G” manufactured by Ouchi Shinsei Chemical Industry
・ Vulcanization accelerator 2: Vulcanization accelerator Sunseller DG made by Sanshin Chemical Industry

Details of the components shown in Tables 3 and 4 are as follows.
SBR1: Nipol NS530 manufactured by Zeon Corporation (similar to SBR1 in Table 1)
-SBR3: Nipol NS570 manufactured by Zeon Corporation (similar to SBR3 in Table 1)
SBR5: Styrene butadiene rubber oiled 37.5 parts by weight with respect to 100 parts by weight of SBR, 72% by weight of Vn (1,2-bond) in SBR, weight average molecular weight 11.7 × 10 ⁵ , Dow Chemical SLR6430
-TEMPO:

Reagent

2,2,6,6-Tetramethylpiperidine 1-Oxyl ^O Free Radical manufactured by Tokyo Chemical Industry Co., Ltd.
The other components are the same as those in Table 1.

Details of the components shown in Tables 5 and 6 are as follows.
-SBR1: Same as SBR1 in Table 1-SBR3: Same as SBR3 in Table 1-SBR5: Same as SBR5 in Table 3-DTP: Zinc dithiophosphate represented by the following formula, Rhenocure ZBOP / S

(In the formula, R ¹ and R ² are alkyl groups represented by C _p H _{2p + 1} (p = 1 to 18), and n is 1.)

Components other than the above are the same as in Table 1.

Details of the components shown in Table 7 are as follows.
GM: Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.) (compound represented by the above formula (5), wherein R ⁵¹ is a hydrogen atom, R ⁵² and R ⁵⁵ are tert-butyl groups, and R ⁵³ and R ⁵⁴ are methyl) Base.)
GS: Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) (compound represented by the above formula (5), wherein R ⁵¹ is a methyl group, R ⁵² , R ⁵³ , R ⁵⁴ and R ⁵⁵ are 1,1-dimethylpropyl) Base.)
The other components are the same as those in Table 1.

As is clear from the results shown in the table, the aromatic vinyl-conjugated diene copolymer in which the 1,2-bond in the conjugated diene is 20 to 40% by weight is not included, and the average vinyl content in the diene rubber is high. When Comparative Example [I] -1 was mixed at 135 ° C., poor mixing occurred, and the rubber surface obtained after extrusion of the unvulcanized compound was rough and inferior in workability. Comparative Examples [I] -2 and 3 having a mixing temperature of 140 ° C. or higher had a high relative radical concentration, and the rubber surface obtained after extrusion of the unvulcanized compound was rough and the processability was poor. Comparative Example [I] -4 in which the amount of the silane coupling agent represented by the formula (1) is less than 0.5 parts by weight, an aromatic in which the 1,2-bond in the conjugated diene is 20 to 40% by weight Comparative Example [I] -7 containing one or more vinyl-conjugated diene copolymers in an amount of less than 30% by weight and the total amount of 1,2-bonds being less than 10% by weight in the total amount of diene rubber is 60 The tan δ was high and the rolling resistance was high. Comparative Example [I] -5 in which the amount of the silane coupling agent represented by the formula (1) exceeds 20 parts by weight, Comparative Example in which the total amount of 1,2-bonds exceeds 55% by weight in the total amount of the diene rubber I] -6, Comparative Example [90] containing more than 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight -8 had a rough rubber surface obtained after extrusion of the unvulcanized compound and was inferior in workability.
Comparative Example [II] -1 and Comparative Example [III] -1, in which the total amount of 1,2-bonds exceeds 55% by weight of the total amount of diene rubber, are processed with a rough rubber surface obtained after extrusion of the unvulcanized compound. Inferior. Comparative Examples [II] -2, 3 and Comparative Examples [III] -2, 3 with a mixing temperature of 140 ° C. or higher have a high relative radical concentration, and the rubber surface obtained after extrusion of the unvulcanized compound is rough and has poor processability. The Mooney viscosity was high.
On the other hand, Examples [I] -1 to 11, Examples [II] -1 to 5, Examples [III] -1 to 5, and Examples [IV] -1 to 4 are poorly mixed and / or Alternatively, the generation of radicals is suppressed, and the processability (low viscosity of the compound, extruding is possible, and the rubber surface after extrusion is smooth) is excellent, and 60 ° C. tan δ can be reduced.

1 tread part 12 tread rubber layer

Claims

The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which the 1,2-bond in the conjugated diene is 20 to 40% by weight, and the 1,2-bonds Is 10 to 55% by weight of the total amount of the diene rubber,
The diene rubber is produced by a mixing step of mixing 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica with respect to 100 parts by weight of the diene rubber, A rubber composition for tires, wherein no vulcanizing agent is used in the mixing step, and the mixing temperature in the mixing step is less than 140 ° C.

[In the formula, at least one of R 11 , R 12 and R 13 is —O— (R 15 —O) m —R 16 (R 15 is a divalent hydrocarbon group having 1 to 30 carbon atoms. R 16 is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and m is an integer of 1 to 30 , and the plurality of R 15 when R 15 is plural is may be the same or different.),
When one or two of R 11 , R 12 and R 13 are the aforementioned —O— (R 15 —O) m —R 16 , the remaining group is substituted with an alkyl group having 1 to 12 carbon atoms, —O —R 17 (R 17 is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms.) , A hydrogen atom or an aryl group having 6 to 30 carbon atoms,
R 11 , R 12 and R 13 may be the same or different,
R 14 is a divalent hydrocarbon group having 1 to 30 carbon atoms. ]
In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the following formula (3), the following formula (4) Using at least one radical trapping agent selected from the group consisting of a phosphite compound represented by the following formula, an acrylate represented by the following formula (5), a phenol compound represented by the following formula (6) and a lactone compound, The tire rubber composition according to claim 1, wherein the amount of the agent is 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber.

(In the formula (2), R 21 and R 22 are each independently an alkyl group having 1 to 18 carbon atoms, and n is 0 or 1. A plurality of R 21 and R 22 are the same, respectively. May be different.)

(In the formula (3), R 31 is .R 32 representing an alkylene group having 1 to 12 carbon atoms, R 31 and R 32 in. A plurality of an alkyl group having 1 to 30 carbon atoms, a respectively identical Or different.)

(In the formula (4), R 41 represents an alkoxy group having 1 to 4 carbon atoms. R 42 and R 43 each independently represents an alkyl group having 1 to 4 carbon atoms. R 44 represents hydrogen. .q representing the atom or an alkyl group having 1 to 4 carbon atoms is an integer of 0 or more, r is integer of 2 or more, q and r satisfy the relationship of q + r = 3. plurality of R 42, R 43 and R 44 may be the same or different.)

(In formula (5), R 51 to R 55 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.)

(In the formula (6), R 61 , R 62 and R 63 each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom, and R 61 , R 62 and R 63 (At least two of them represent a hydrocarbon group containing an alkyl group having 4 to 20 carbon atoms and optionally containing a hetero atom.)
The rubber composition for tire according to claim 1 or 2, wherein one or more of the aromatic vinyl-conjugated diene copolymers have a hydroxyl group at a terminal.
The tire according to any one of claims 1 to 3, wherein a plasticizer is further used in the mixing step, and the amount of the plasticizer is 35 parts by weight or less with respect to 100 parts by weight of the diene rubber. Rubber composition.
After the mixing step, a glycol compound and / or a silane compound having an alkyl group is blended as a dispersion aid, and the amount of the dispersion aid is 0.5 to 5 parts by weight with respect to 100 parts by weight of the diene rubber. The tire rubber composition according to any one of claims 1 to 4, wherein the rubber composition is for tires.
The plasticizer according to claim 5, wherein a plasticizer is further used in the mixing step, and a total amount of the dispersion aid and the plasticizer is 35 parts by weight or less with respect to 100 parts by weight of the diene rubber. Rubber composition for tires.
7. The diene rubber according to claim 1, further comprising at least one selected from the group consisting of an aromatic vinyl-conjugated diene copolymer having 1,2-linkage of less than 20% by weight, butadiene rubber and natural rubber. A rubber composition for a tire according to claim 1.
The diene rubber contains 30 to 90% by weight of one or more aromatic vinyl-conjugated diene copolymers in which 1,2-bond in the conjugated diene is 20 to 40% by weight, The total amount of bonds is 10 to 55% by weight in the total amount of the diene rubber,
The diene rubber is produced by a mixing step of mixing 0.5 to 20 parts by weight of a silane coupling agent represented by the following formula (1) and 20 to 120 parts by weight of silica with respect to 100 parts by weight of the diene rubber, The manufacturing method of the rubber composition for tires which does not use a vulcanizing agent in a mixing process, and the mixing temperature in the said mixing process is less than 140 degreeC.

[In the formula, at least one of R 11 , R 12 and R 13 is —O— (R 15 —O) m —R 16 (R 15 is a divalent hydrocarbon group having 1 to 30 carbon atoms. R 16 is an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms, and m is an integer of 1 to 30 , and the plurality of R 15 when R 15 is plural is may be the same or different.),
When one or two of R 11 , R 12 and R 13 are the aforementioned —O— (R 15 —O) m —R 16 , the remaining group is substituted with an alkyl group having 1 to 12 carbon atoms, —O —R 17 (R 17 is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms.) , A hydrogen atom or an aryl group having 6 to 30 carbon atoms,
R 11 , R 12 and R 13 may be the same or different,
R 14 is a divalent hydrocarbon group having 1 to 30 carbon atoms. ]
In the mixing step, 2,2,6,6-tetramethylpiperidine, a dialkyldithiophosphate compound represented by the following formula (2), a thiodicarboxylic acid ester represented by the following formula (3), the following formula (4) ), A phosphite compound represented by the following formula (5), at least one radical trapping agent selected from the group consisting of a phenol compound and a lactone compound represented by the following formula (6), The method for producing a tire rubber composition according to claim 8, wherein the amount of the trapping agent is 0.1 to 5 parts by weight with respect to 100 parts by weight of the diene rubber.

(In the formula (2), R 21 and R 22 are each independently an alkyl group having 1 to 18 carbon atoms, and n is 0 or 1. A plurality of R 21 and R 22 are the same, respectively. May be different.)

(In the formula (3), R 31 is .R 32 representing an alkylene group having 1 to 12 carbon atoms, R 31 and R 32 in. A plurality of an alkyl group having 1 to 30 carbon atoms, a respectively identical Or different.)

(In the formula (4), R 41 represents an alkoxy group having 1 to 4 carbon atoms. R 42 and R 43 each independently represents an alkyl group having 1 to 4 carbon atoms. R 44 represents hydrogen. .q representing the atom or an alkyl group having 1 to 4 carbon atoms is an integer of 0 or more, r is integer of 2 or more, q and r satisfy the relationship of q + r = 3. plurality of R 42, R 43 and R 44 may be the same or different.)

(In formula (5), R 51 to R 55 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.)

(In the formula (6), R 61 , R 62 and R 63 each independently represents a hydrocarbon group having 1 to 30 carbon atoms which may contain a hetero atom, and R 61 , R 62 and R 63 (At least two of them represent a hydrocarbon group containing an alkyl group having 4 to 20 carbon atoms and optionally containing a hetero atom.)
A pneumatic tire using the tire rubber composition according to any one of claims 1 to 7 or the tire rubber composition produced by the method for producing a tire rubber composition according to claim 8 or 9 as a tire tread. .