JP5912934B2 - Rubber composition for tire and pneumatic tire - Google Patents

Description

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

Conventionally, the rubber composition for tires has been used as a filler with carbon black, which can easily interact with the rubber component and has an excellent reinforcing effect. However, in recent years, from the viewpoint of low fuel consumption and environmental protection. White fillers such as silica are used in place of carbon black.

However, white fillers such as silica have a lower affinity with natural rubber, butadiene rubber, styrene butadiene rubber, etc., which are widely used for tires, compared to carbon black, and wear resistance and mechanical strength (tensile strength and fracture) Often inferior in terms of elongation.

As a method for solving this problem, it has been proposed to use a silane coupling agent having reactivity with a white filler such as a rubber component or silica, but the reaction with the white filler should be sufficiently advanced. However, the unreacted white filler may remain poorly dispersed and the desired performance may not be exhibited. Furthermore, in order to prevent this, if a large amount of silane coupling agent is blended, due to the residual silane coupling agent, rubber burn during processing, wear resistance of vulcanized rubber and mechanical strength may be reduced. is there.

In addition, in order to prevent the wear resistance of the white filler compounded rubber from decreasing, a method of blending a low molecular weight diene rubber can be considered, but the matrix rubber components are incompatible with each other, such as styrene butadiene rubber and butadiene rubber. In such a case, there is a problem in the dispersibility of the filler, for example, the filler is unevenly distributed only in one rubber component, and it is difficult to obtain desired performance such as low fuel consumption and wet grip performance.

Patent Document 1 discloses a tire rubber composition containing a basic aqueous solution having a pH of 8 to 12 and silica for the purpose of enhancing the compatibility between silica and rubber, but the interaction between rubber and silica is disclosed. Cannot be sufficiently obtained, and the improvement effect such as low fuel consumption is not satisfactory. Therefore, it is desired to provide a silica-containing rubber that can improve fuel economy, wet grip performance, wear resistance, and processability in a well-balanced manner.

JP 2000-219779 A

An object of the present invention is to solve the above-mentioned problems and provide a rubber composition for a tire that improves the fuel efficiency, wet grip performance, wear resistance, and processability in a well-balanced manner, and a pneumatic tire using the same. And

The present invention relates to a tire rubber composition containing 10 to 200 parts by weight of a white filler and 0.1 to 40 parts by weight of a cyclized rubber with respect to 100 parts by weight of a rubber component.

The cyclization rate of the cyclized rubber is preferably 0.1 to 40%.
The cyclized rubber is preferably at least one selected from the group consisting of cyclized natural rubber, cyclized isoprene rubber, and cyclized butadiene rubber.

The cyclized rubber is preferably a modified cyclized rubber modified with a polar group-containing compound.
The white filler is preferably silica and / or aluminum hydroxide.

It is preferable that the content of the softening agent other than the cyclized rubber is less than 20 parts by mass with respect to 100 parts by mass of the rubber component.
The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, since the rubber composition for a tire includes 10 to 200 parts by weight of a white filler and 0.1 to 40 parts by weight of a cyclized rubber with respect to 100 parts by weight of the rubber component, The wet grip performance, wear resistance, and workability can be improved in a well-balanced manner.

The rubber composition for tires of the present invention contains a predetermined amount of a rubber component, a white filler and a cyclized rubber.

A rubber compounded with a white filler such as silica generally has low dispersibility of the filler and it is difficult to obtain a desired performance. However, in the present invention, by adding a cyclized rubber, silica and the like are mixed with a rubber component. Interaction is enhanced. Therefore, the dispersibility of the white filler is improved, fuel efficiency, abrasion resistance, wet grip performance can be improved, and good workability can be obtained, and the balance of these performances can be improved synergistically.

Furthermore, by using a cyclized rubber having a predetermined cyclization rate, the dispersibility of a white filler such as silica is dramatically improved, and the performance balance can be remarkably improved.
Moreover, the performance balance can be remarkably improved by using a polar group-containing compound-modified cyclized rubber as the cyclized rubber.

Rubber components include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), diene rubbers such as butadiene isoprene rubber, and chlorinated butyl rubber. Butyl rubbers such as those obtained by condensing or modifying these rubbers can also be used. Among these, diene rubber is preferable from the viewpoint of the performance balance, and for example, SBR, BR and the like can be suitably used. These rubber components may be used alone or in combination of two or more.

In the present invention, from the viewpoint of the performance balance, the content of the diene rubber in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass.

The SBR is not particularly limited, and for example, those commonly used in the tire industry such as Nipol NS116R manufactured by Nippon Zeon Co., Ltd. can be used.

When the rubber composition of the present invention contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more. If it is less than 40% by mass, the wet grip performance tends to decrease. The content of the SBR is preferably 90% by mass or less, more preferably 80% by mass or less. If it exceeds 90% by mass, the fuel efficiency tends to deteriorate.

The BR is not particularly limited. For example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having high cis content such as BR150B, VCR412 manufactured by Ube Industries, Ltd., VCR617, etc. Commonly used in the tire industry such as BR containing syndiotactic polybutadiene crystals can be used.

When the rubber composition of the present invention contains BR, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. . If it is less than 5% by mass, the wear resistance tends to decrease. The BR content is preferably 60% by mass or less, more preferably 50% by mass or less. If it exceeds 60% by mass, the wet grip performance tends to decrease.

It does not specifically limit as a white filler, A well-known thing can be used in the tire field | area, For example, a silica, a calcium carbonate, aluminum hydroxide etc. are mentioned. Among these, silica and / or aluminum hydroxide is preferable from the viewpoint that the effects of the present invention can be sufficiently obtained.

Examples of the silica include, but are not limited to, dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and wet process silica is preferable because it has many silanol groups.

Nitrogen adsorption specific surface area of the silica _(N 2 SA) of preferably at least ^{40 m} 2 / g, more preferably at least ^{50m 2 / g, 100m 2 /} g or more, and particularly preferably equal to or greater than 150m ² / g. If it is less than 40 m < ² > / g, there exists a tendency for the fracture strength after vulcanization to fall. The _N 2 SA of the silica is preferably not more than 500 meters ² / g, more preferably at most 300m ² / g. When it exceeds 500 m ² / g, there is a tendency that low heat build-up and rubber processability are lowered.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

It does not specifically limit as aluminum hydroxide, A general thing can be used in the tire industry.

The average particle diameter of aluminum hydroxide is preferably 0.1 to 8 μm, more preferably 0.1 to 5 μm, and the BET specific surface area is preferably 1 m ² / g or more, more preferably 1 to 50 m ² / g. More preferably, it is 2-20 m < ² > / g, Most preferably, it is 3-10 m < ² > / g. When the average particle size is less than 0.1 μm, the kneading workability is lowered while the improvement in grip force cannot be expected, and when it exceeds 8 μm, the elastic modulus is lowered and the wear resistance tends to be lowered. Further, when the BET specific surface area is less than 1 m ² / g, the effect of improving grip performance is small, and when it exceeds 50 m ² / g, the dispersibility tends to decrease. In addition, the average particle diameter of aluminum hydroxide is a number average particle diameter, and is measured by a transmission electron microscope, and the BET specific surface area is measured by the same method as that for silica.

Content of a white filler is 10 mass parts or more with respect to 100 mass parts of rubber components, Preferably it is 15 mass parts or more, More preferably, it is 20 mass parts or more. If it is less than 10 parts by mass, the low heat build-up may be insufficient. Moreover, this content is 200 mass parts or less, Preferably it is 150 mass parts or less, More preferably, it is 120 mass parts or less. When it exceeds 200 parts by mass, it becomes difficult to disperse the filler into the rubber, and the processability of the rubber tends to deteriorate.

In the present invention, a reinforcing filler other than the white filler may be blended, but the content of the white filler in 100% by mass of the reinforcing filler is preferably 20% by mass or more, and 50 More preferably, it is more preferably 70% by mass or more. If it is less than 20% by mass, the low heat build-up tends to be insufficient.

The rubber composition of the present invention may contain a silane coupling agent.
The silane coupling agent is not particularly limited, and conventionally known silane coupling agents can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-tri Methoxysilylpropyl) sulfide type such as tetrasulfide; mercapto type such as 3-mercaptopropyltrimethoxysilane; vinyl type such as vinyltriethoxysilane; amino type such as 3-aminopropyltriethoxysilane; γ-glycidoxypropyl Examples thereof include glycidoxy type such as triethoxysilane; nitro type such as 3-nitropropyltrimethoxysilane; chloro type such as 3-chloropropyltrimethoxysilane.

The content of the silane coupling agent is preferably 0 to 20 parts by mass with respect to 100 parts by mass of the rubber component. If the amount exceeds 20 parts by mass, the effect of dispersing the filler cannot be obtained for an increase in cost, and further, the reinforcing property and wear resistance may be lowered, and unreacted silane coupling agent remains. As a result, there is a risk that the rubber will be burned during processing and the breaking performance of the rubber after vulcanization may be reduced. The lower limit is more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and the upper limit is more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less.

As the other reinforcing filler, carbon black is preferably used from the viewpoint of obtaining a sufficient reinforcing effect. Carbon black is not particularly limited, and examples thereof include SAF, ISAF, HAF, MAF, FEF, SRF, and GPF.

Nitrogen adsorption specific surface area _(N 2 SA) of carbon black is usually 5 to 200 m ² / g, the lower limit is preferably ^{50 m} 2 / g, the upper limit is 150 meters ² / g. Carbon black has a dibutyl phthalate (DBP) absorption amount of usually 5 to 300 ml / 100 g, preferably a lower limit of 80 ml / 100 g and an upper limit of 180 ml / 100 g. The nitrogen adsorption specific surface area is measured according to ASTM D4820-93, and the DBP absorption is measured according to ASTM D2414-93.

The content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, sufficient reinforcement may not be obtained. The content of carbon black is preferably 60 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 10 parts by mass or less. If it exceeds 60 parts by mass, the fuel efficiency tends to deteriorate.

As the cyclized rubber, compounds having various chemical structures have been proposed, but the cyclized rubber in the present invention is not limited to any of them, and any compound can be used. The cyclized rubber may be unmodified, modified, or a mixture of plural kinds. In the present invention, the cyclized rubber is not a rubber component, but is a softening agent component that improves the compatibility of the rubber component with a white filler such as silica and has a reactivity, and disperses the white filler such as silica. It also has the effect of

The cyclization rate of the cyclized rubber is preferably 0.1% or more, more preferably 1% or more, and further preferably 3% or more. If it is less than 0.1%, sufficient interaction with the white filler cannot be obtained, and the fuel efficiency may be deteriorated. The cyclization rate is preferably 40% or less, more preferably 35% or less, and still more preferably 30% or less. If it exceeds 40%, the cyclized rubber may gel or adhere to the kneader.

The cyclization rate is the ratio of double bonds reacted by the cyclization reaction to the number of double bonds of the raw rubber component (conjugated diene polymer) before the cyclization reaction. For example, by measuring the peak areas of protons derived from double bonds before and after the cyclization reaction of the conjugated diene polymer used as a raw material by ¹ H-NMR analysis, the cyclization reaction when the pre-cyclization reaction is 100 The ratio of the double bond remaining in the subsequent cyclized product can be obtained and measured as a value (%) represented by the formula: (100−the ratio of the double bond remaining in the cyclized product).

The number average molecular weight (Mn) of the cyclized rubber is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, and 10,000 to 300,000. More preferably. If it is less than 1,000, the wear resistance and fuel efficiency may be deteriorated, and if it exceeds 1,000,000, the viscosity increases and the workability may be deteriorated.

The molecular weight distribution of the cyclized rubber, that is, the weight average molecular weight / number average molecular weight (Mw / Mn) is preferably 4 or less.
In addition, Mw / Mn is a standard polystyrene conversion value measured by GPC.

The glass transition temperature (Tg) of the cyclized rubber is not particularly limited and is usually −100 to 100 ° C., but preferably −90 to 80 ° C., more preferably −90 to 40 from the viewpoint of the effect of the present invention. ° C, particularly preferably -90 to 20 ° C, most preferably -90 to 5 ° C.

The gel amount of the cyclized rubber is preferably 10% by mass or less, more preferably 5% by mass or less from the viewpoint of the effect of the present invention, and a gel having substantially no gel is particularly preferable.

As the cyclized rubber, a conjugated diene polymer cyclized product can be preferably used. The conjugated diene polymer cyclized product is prepared by (co) polymerizing a conjugated diene monomer or a conjugated diene monomer and another monomer copolymerizable with the conjugated diene monomer by a known method. And the like obtained by cyclizing the conjugated diene polymer.

Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl- Examples include 1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, and the like. These monomers may be used alone or in combination of two or more.

Examples of other monomers copolymerizable with the conjugated diene monomer include styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, and p-tert. -Butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, 2-methyl-1,4-dichlorostyrene, Aromatic vinyl monomers such as 2,4-dibromostyrene and vinylnaphthalene; Chain olefin monomers such as ethylene, propylene and 1-butene; Cyclic olefin monomers such as cyclopentene and 2-norbornene; 1,5 -Hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-no Non-conjugated diene monomers such as rubornene; (meth) acrylic acid esters such as methyl (meth) acrylate and ethyl (meth) acrylate; (meth) acrylonitrile, (meth) acrylamide and the like. These monomers may be used alone or in combination of two or more.

The content of the conjugated diene monomer unit in the conjugated diene polymer may be appropriately selected within a range not impairing the effects of the present invention, but is preferably 40 mol% or more, more preferably 60 mol% or more, and still more preferably. Is 80 mol% or more.

As the cyclized rubber, the conjugated diene polymer cyclized product described above can be used. Among them, cyclized natural rubber, cyclized isoprene rubber, cyclized butadiene rubber and the like are particularly preferable from the viewpoint of the effect of the present invention.

As described above, the conjugated diene polymer cyclized product can be prepared by cyclizing the conjugated diene polymer, but this cyclization reaction can be carried out by a known method, for example, after the (co) polymerization reaction, one-pot reaction as it is. And a method of cyclization by adding a cyclization catalyst in (3), (co) polymerization, a method of re-creating a solution from a dried conjugated diene polymer, and the like.

Here, in the cyclization reaction, for example, a known cyclization catalyst is allowed to act directly on raw rubber or on a rubber solution, and a part of chain molecules in the rubber molecule is cyclized to reduce double bonds. Thereby obtaining a cyclized rubber. Examples of the cyclization catalyst include organic sulfonic acids such as sulfuric acid and p-toluenesulfonic acid, and chlorosulfonic acid.

As the cyclized rubber, a modified cyclized rubber modified with a polar group-containing compound is preferable. Thereby, the performance balance can be further improved. The modified cyclized rubber can be prepared, for example, by subjecting the conjugated diene polymer cyclized product to a modification reaction with a polar group-containing compound.

As the polar group-containing compound used for the modification reaction, for example, a compound capable of introducing a polar group into a conjugated diene polymer cyclized product can be used, and an acid anhydride group, a carboxyl group, a hydroxyl group, a thiol group, an ester group, Examples thereof include ethylenically unsaturated compounds having a polar group such as an epoxy group, amino group, amide group, cyano group, silyl group, and halogen. Here, the polar group is preferably an acid anhydride group, a carboxyl group, or a hydroxyl group.

Examples of the compound having an acid anhydride group or a carboxyl group include maleic anhydride, itaconic anhydride, aconitic anhydride, norbornene dicarboxylic acid anhydride, ethylenically unsaturated compounds such as acrylic acid, methacrylic acid and maleic acid. It is done. Of these, maleic anhydride is particularly preferred from the viewpoint of reactivity.

Examples of the ethylenically unsaturated compound having a hydroxyl group include hydroxyalkyl esters of unsaturated acids such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; N-methylol (meth) acrylamide , N- (2-hydroxyethyl) (meth) acrylamide and other unsaturated acid amides having a hydroxyl group; polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono And polyalkylene glycol monoesters of unsaturated acids such as (meth) acrylate; polyhydric alcohol monoesters of unsaturated acids such as glycerol mono (meth) acrylate; and the like. Of these, hydroxyalkyl esters of unsaturated acids are preferable, and 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate are particularly preferable.

Examples of other ethylenically unsaturated compounds having a polar group include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and dimethylamino. Examples include propyl (meth) acrylate, (meth) acrylamide, (meth) acrylonitrile and the like.

The reaction for introducing the polar group is not particularly limited. For example, when an ethylenically unsaturated compound is added, a known reaction generally called an ene addition reaction or a graft polymerization reaction may be used. The reaction is preferably performed by heating in a solution in a dry air stream.

The content of the cyclized rubber is 0.1 parts by mass or more, preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content is 40 mass parts or less, Preferably it is 30 mass parts or less. If it is less than 0.1 part by mass, the effect of dispersing the white filler is not sufficient, and if it exceeds 40 parts by mass, the physical properties of the rubber may be lowered.

In addition to the above components, the rubber composition of the present invention comprises a softener such as oil and wax, an anti-aging agent, an additive such as stearic acid and zinc oxide, a vulcanizing agent such as sulfur, a vulcanization accelerator, and a vulcanizing agent. You may mix | blend a promotion adjuvant etc. suitably.

For the reason that the effects of the present invention can be obtained satisfactorily, the content of the softening agent other than the cyclized rubber with respect to 100 parts by mass of the rubber component is preferably less than 20 parts by mass, more preferably 10 parts by mass or less, and still more preferably. 5 parts by mass or less. The content includes the amount of oil contained in the oil-extended rubber.

Examples of the softening agent other than the cyclized rubber include oil and wax.
Examples of the oil include process oils such as paraffinic, naphthenic, and aromatic process oils. Examples of the wax include petroleum waxes such as paraffin wax, natural waxes (natural waxes) such as carnauba wax, beeswax, and candelilla wax. These may be used alone or in combination of two or more.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Etc. These vulcanization accelerators may be used alone or in combination of two or more. Of these, sulfenamide vulcanization accelerators are preferred.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N -Dicyclohexyl-2-benzothiazolylsulfenamide (DCBS) and the like. Of these, TBBS is preferable.

The content of the vulcanization accelerator is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 5 parts by mass or less, more preferably 100 parts by mass of the rubber component. Is 3 parts by mass or less. By adjusting within the above range, the effect of the present invention can be obtained more suitably.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading each of the above components with a kneader such as a Banbury mixer, a kneader, or an open roll, and then vulcanizing. The rubber composition can be used for each member of a tire and the arrangement is not limited, but it can be particularly suitably used for a tread.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, by extruding a rubber composition containing the above components in accordance with the shape of a tread or the like at an unvulcanized stage, and molding it with a tire molding machine by a normal method along with other tire members, Form an unvulcanized tire. The pneumatic tire of the present invention can be manufactured by heating and pressurizing the unvulcanized tire in a vulcanizer. The pneumatic tire is preferably used as a tire for passenger cars, a tire for trucks and buses, a tire for motorcycles, a tire for competition, and the like.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

(Production Example 1)
A pressure-resistant reactor equipped with a stirrer substituted with nitrogen was charged with 1400 g of dehydrated toluene and 18 mmol of n-butyllithium, and the internal temperature was maintained at 60 ° C. 487 g of isoprene was continuously added to the reactor over 15 minutes, and the internal temperature was controlled not to exceed 75 ° C. Thereafter, the mixture was reacted at 70 ° C. for 10.5 hours, and then 1.4 mmol of methanol was added as a polymerization terminator to terminate the polymerization reaction.
After stopping the polymerization reaction, the temperature was raised to 80 ° C., 4.24 g of p-toluenesulfonic acid was added, and the cyclization reaction was performed for 1 hour while maintaining the temperature at 80 ° C. Subsequently, an aqueous solution in which 1.70 g of sodium carbonate was dissolved in 5.1 g of water was added to stop the cyclization reaction, and the reaction solution was filtered to remove the catalyst residue. After adding 0.4 g of anti-aging agent (Irganox 1010: manufactured by Ciba Specialty Chemicals) to this solution, toluene was distilled off and dried under reduced pressure to obtain an unmodified cyclized rubber 1.

(Production Example 2)
A pressure-resistant reactor equipped with a stirrer substituted with nitrogen was charged with 1400 g of dehydrated toluene and 18 mmol of n-butyllithium, and the internal temperature was maintained at 60 ° C. 487 g of isoprene was continuously added to the reactor over 15 minutes, and the internal temperature was controlled not to exceed 75 ° C. Thereafter, the mixture was reacted at 70 ° C. for 10.5 hours, and then 1.4 mmol of methanol was added as a polymerization terminator to terminate the polymerization reaction.
After stopping the polymerization reaction, the temperature was raised to 80 ° C., 4.24 g of p-toluenesulfonic acid was added, and the cyclization reaction was performed for 1 hour while maintaining the temperature at 80 ° C. Subsequently, an aqueous solution in which 1.70 g of sodium carbonate was dissolved in 5.1 g of water was added to stop the cyclization reaction, and the reaction solution was filtered to remove the catalyst residue.
The reaction solution was heated to 160 ° C. and 15 g of maleic anhydride was added. Next, after reacting at 160 ° C. for 1 hour, unreacted maleic anhydride and toluene were distilled off, and 0.6 g of Irganox 1010 (manufactured by Ciba Specialty Chemicals) was added, followed by drying under reduced pressure. Modified cyclized rubber 2 was obtained.

(Production Example 3)
In a pressure vessel equipped with a stirrer purged with nitrogen, 300 g of liquid polyisoprene (Kuraray LIR-30: Mn = 28,000) and 700 g of toluene were charged. The mixture was heated to 80 ° C. to completely dissolve polyisoprene, and then 2 g of p-toluenesulfonic acid was added to carry out a cyclization reaction while maintaining the internal temperature at 80 ° C. After reacting for 1 hour, a 25% aqueous solution of sodium carbonate containing 0.8 g of sodium carbonate was added to stop the reaction, stirred at 80 ° C. for 30 minutes, and then filtered to remove the catalyst residue.
The reaction solution was heated to 160 ° C. and 14 g of maleic anhydride was added. Next, after reacting at 160 ° C. for 1 hour, unreacted maleic anhydride and toluene were distilled off, and Irganox 1010 (manufactured by Ciba Specialty Chemicals) 0.3 g was added, followed by drying under reduced pressure. Modified cyclized rubber 3 was obtained.

(Production Example 4)
A modified cyclized rubber 4 was obtained in the same manner as in Production Example 3 except that liquid polybutadiene (manufactured by Sartomer, Rycon 150, Mn = 5,200) was used instead of liquid polyisoprene.

(Production Example 5)
Modified cyclized rubber 5 in the same manner as in Production Example 3 except that polybutadiene (UBEPOL 150L, Mn = 250,000) manufactured by Ube Industries, Ltd. was used instead of liquid polyisoprene, and the cyclization reaction time was changed to 3 hours. Got.

The physical properties of the obtained cyclized rubber (unmodified or modified cyclized rubber) were measured by the following methods, and the results are shown in Table 1.

(Cyclization rate of cyclized rubber)
The cyclization rate of the cyclized rubber was determined from the peak area ratio of protons in the polymer before and after the cyclization reaction by ¹ H-NMR measurement using an NMR apparatus of AV400 manufactured by BRUKER, data analysis software TOP SPIN2.1. . In addition, the detailed cyclization rate calculation method is as having described in the following literature.
Y. Tanaka and H.M. Sato, J .; Polym. Sci: Poly. Chem. Ed. , 17, 3027 (1979)

(Number average molecular weight (Mn) and weight average molecular weight (Mw) of cyclized rubber)
The calibration curve obtained from the molecular weight distribution curve obtained by performing gel permeation (permeation) chromatography of cyclized rubber (GPC, manufactured by Tosoh Corporation) using polystyrene as a standard substance and tetrahydrofuran as a solvent at a temperature of 40 ° C. Mn and Mw were calculated.

(Glass transition temperature Tg of cyclized rubber)
The glass transition temperature of the cyclized rubber was measured using a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd .: SSC5200) under the conditions of a starting temperature of −100 ° C. and a heating rate of 10 ° C./min.

(Gel amount of cyclized rubber)
After 0.2 g of a sample cut to 2 mm square was immersed in 100 ml of toluene for 48 hours, the ratio of the dry weight of the gel remaining on the 80-mesh wire net was shown as a percentage.

Below, the chemical | medical agent used by the Example , the reference example, and the comparative example is shown collectively.
SBR: Nipol NS116 manufactured by ZEON CORPORATION
BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.
Unmodified or modified cyclized rubber 1-5: Production Examples 1-5
Liquid BR: Rycon 150 (Mn = 5200) manufactured by Sartomer
Silica: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by EVONIK-DEGUSSA
Carbon black: Dia Black I manufactured by Mitsubishi Chemical Corporation (ISAF carbon, average particle size 23 nm, DBP oil absorption 114 ml / 100 g)
Aluminum hydroxide: Heidilite H-43 manufactured by Showa Denko KK (average particle size: 0.6 μm, BET specific surface area: 6.5 m ² / g)
Oil: Process X-140 (aromatic process oil) manufactured by Japan Energy Co., Ltd.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Stearic acid: Stearic acid “paulownia” manufactured by NOF Corporation
Zinc oxide: 2 types of anti-aging of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylene manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) Diamine)
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

<Examples , reference examples, and comparative examples>
In accordance with the formulation of Table 2, using a 1.7L Banbury mixer manufactured by Kobe Steel Co., Ltd., chemicals other than sulfur and a vulcanization accelerator were filled to a filling rate of 58%, and 140 rpm at 140 rpm. A kneaded product was obtained by kneading until reaching 0C. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition.
Further, the obtained unvulcanized rubber composition was molded into a predetermined size, and a vulcanized rubber composition was obtained by press vulcanization at 150 ° C. for 20 minutes, and a vulcanization of about 2 mm × 130 mm × 130 mm was obtained. A rubber slab sheet was prepared.

Further, the obtained unvulcanized rubber composition is formed into a tread shape, bonded to another tire member, and vulcanized at 170 ° C. for 15 minutes to produce a test tire (size: 195 / 65R15). did.

The following evaluation was performed about the obtained unvulcanized rubber composition, a vulcanized rubber slab sheet, and a test tire. The results are shown in Table 2.

(Processability)
Based on JIS K6300-1, Mooney viscosity (ML _{1 + 4} ) was measured at 130 ° C., and Comparative Example 1 was taken as 100, and the workability index was calculated from the following formula. The larger the index, the better the processability when unvulcanized.
(Processability index) = (Mooney viscosity of Comparative Example 1) / (Mooney viscosity of each formulation) × 100

(Viscoelasticity test)
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, the loss tangent (tan δ) of the vulcanized rubber slab sheet was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz. The rolling resistance index of Comparative Example 1 was set to 100, and the rolling resistance was indicated by an index according to the following formula. The larger the rolling resistance index, the lower the rolling resistance, which is preferable.
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

(Wet grip performance)
Each test tire was mounted on all wheels of a vehicle (domestic FF2000cc), and the braking distance from an initial speed of 100 km / h was measured on a wet asphalt road surface. The braking distance index of Comparative Example 1 was set to 100, and the index was displayed by the following formula. The larger the index, the better the wet skid performance (wet grip performance).
(Wet grip performance) = (Brake distance of Comparative Example 1) / (Brake distance of each formulation) × 100

(Abrasion resistance)
Using a Lambourne abrasion tester manufactured by Iwamoto Seisakusho, the amount of wear was measured at a surface rotation speed of 50 m / min, an additional load of 3.0 kg, a sandfall of 15 g / min and a slip rate of 20%. The inverse of was taken. And the reciprocal number of the wear amount of the comparative example 1 was set to 100, and the reciprocal number of the wear amount of the other composition was expressed as an index. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.

In Comparative Examples 2 to 3 in which aluminum hydroxide or liquid BR was added to Comparative Example 1, no effect of improving the performance balance was observed. On the other hand, in the rubber compounded with silica, in Reference Example 1 in which unmodified cyclized rubber is used instead of oil, a processability index “99” having no practical problem is obtained, while low fuel consumption (rolling resistance), wet grip Performance and wear resistance could be improved at the same time, and the performance balance could be improved synergistically. Furthermore, even in Examples 2 to 5 using modified cyclized rubber, the fuel economy, wet grip performance, and wear resistance were further improved while obtaining the workability indexes “98” and “99” which are practically no problem. It was clarified that a synergistic improvement effect of the performance balance can be obtained remarkably. Further, in Example 2 in which aluminum hydroxide was further added in Example 2, the performance balance could be improved while obtaining a rolling resistance index “97” and an abrasion resistance index “98”, which had no practical problems.

Claims (5)

Per 100 parts by mass of the rubber component, 10 to 200 parts by weight of white filler, cyclized rubber (unless cyclized rubber is epoxidized natural rubber) and 0.1 to 40 parts by mass seen including,
The cyclization rate of the cyclized rubber is 0.1 to 40%,
The rubber composition for a tire , wherein the cyclized rubber is a modified cyclized rubber modified with a polar group-containing compound . The cyclized rubber, cyclized natural rubber, cyclized isoprene rubber and cyclizing at least one kind of claim 1 Symbol placement tire rubber composition is selected from the group consisting of butadiene rubber. The tire rubber composition according to claim 1 or 2, wherein the white filler is silica and / or aluminum hydroxide. The tire rubber composition according to any one of claims 1 to 3 , wherein a content of a softening agent other than the cyclized rubber is less than 20 parts by mass with respect to 100 parts by mass of the rubber component. The pneumatic tire produced using the rubber composition in any one of Claims 1-4 .