JP2018165087A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having excellent air retention and adhesiveness at an interface (particularly, a joint portion) between an inner liner and an insulation. SOLUTION: The pneumatic tire has a carcass, an insulation adjacent to the carcass on the inner side in the radial direction of the tire, and an inner liner adjacent to the inner liner on the inner side in the radial direction of the tire. It comprises a rubber composition for an inner liner containing a plastic elastomer and a butyl rubber, and the insulation relates to a pneumatic tire composed of an insulation rubber composition containing a butyl rubber and an isoprene rubber. [Selection diagram] Fig. 1

Description

The present invention relates to a pneumatic tire.

The pneumatic tire is composed of various members such as an inner liner in addition to the tread in contact with the road surface. The inner liner is a tire member that exhibits air retention by reducing the amount of air leakage (air permeation amount) from the inside of the tire to the outside. The member is provided with air retention by blending butyl rubber such as butyl rubber which does not easily transmit air (for example, Patent Document 1). On the other hand, attempts have been made to blend a styrene-isobutylene-styrene block copolymer in order to impart air retention.

JP 2014-227494 A

As a result of the study by the present inventors, in a rubber composition for an inner liner, when a thermoplastic elastomer such as a styrene-isobutylene-styrene block copolymer is blended, the air retention is improved, but the vulcanized adhesiveness with different rubbers It turned out that turning (peeling) occurred at the interface between the inner liner and the insulation adjacent to the inner liner when the tire was run. It has also been found that this peeling is likely to occur particularly at the joint portion generated during the molding of the tire.
In order to solve this problem, a method of sticking a butyl tape to the joint portion is also conceivable, but it is not sufficient, for example, there is a concern that peeling occurs outside the joint portion.
An object of the present invention is to solve the above-mentioned problems and to provide a pneumatic tire excellent in air retainability and adhesiveness at an interface (particularly a joint portion) between an inner liner and an insulation.

The present invention is a pneumatic tire having a carcass, an installation adjacent to the carcass on the inner side in the tire radial direction, and an inner liner adjacent to the installation on the inner side in the tire radial direction,
The inner liner is composed of a rubber composition for an inner liner including a thermoplastic elastomer and a butyl rubber,
The insulation relates to a pneumatic tire made of a rubber composition for insulation including butyl rubber and isoprene rubber.

According to the present invention, there is provided a pneumatic tire having a carcass, an insulation adjacent to the carcass on the inner side in the tire radial direction, and an inner liner adjacent to the insulation on the inner side in the tire radial direction, wherein the inner liner is , Comprising a rubber composition for an inner liner containing a thermoplastic elastomer and a butyl rubber, and the insulation is a pneumatic tire comprising a rubber composition for an insulation containing a butyl rubber and an isoprene rubber. Therefore, it has excellent air retention and adhesion at the interface between the inner liner and the insulation (particularly the joint portion).

1 is a cross-sectional view illustrating a part of a pneumatic tire according to an embodiment of the present invention.

The pneumatic tire of the present invention is a pneumatic tire having a carcass, an installation adjacent to the carcass in a tire radial inner side, and an inner liner adjacent to the installation in a tire radial inner side,
The inner liner is composed of a rubber composition for an inner liner including a thermoplastic elastomer and a butyl rubber,
The insulation is composed of a rubber composition for insulation containing butyl rubber and isoprene rubber.

In the present invention, it is presumed that the following effects can achieve both air retention and adhesiveness (hereinafter also simply referred to as adhesiveness) at the interface between the inner liner and the insulation (in particular, the joint portion). Is done.
In the present invention, the inner liner containing a thermoplastic elastomer such as a styrene-isobutylene-styrene block copolymer is combined with an insulation containing a butyl rubber or an isoprene rubber to improve the adhesion between both members. It is possible to improve adhesion at the interface between the inner liner and the insulation (particularly the joint portion), and to suppress peeling at the joint interface.
Thus, in the present invention, even when an inner liner blended with a thermoplastic elastomer such as a styrene-isobutylene-styrene block copolymer is used, the adhesiveness of both members is improved by combining the specific insulation. Therefore, it is possible to employ an inner liner excellent in air retention, which is blended with a thermoplastic elastomer such as a styrene-isobutylene-styrene block copolymer.
Further, in the present invention, in addition to the good air retention due to the thermoplastic elastomer such as styrene-isobutylene-styrene block copolymer blended in the inner liner and the butyl rubber, the insulation also contains the butyl rubber. Therefore, better air retention can be obtained.
Thus, in the present invention, air retention and adhesiveness can be synergistically improved by the synergistic action of the specific inner liner and the specific insulation.

The pneumatic tire of the present invention includes a carcass, an insulation adjacent to the carcass on the inner side in the tire radial direction, and an inner liner adjacent to the insulation on the inner side in the tire radial direction.

The carcass is a member formed of a tire cord and a tire cord-covered rubber layer, and specifically, a member shown in FIG. 1 and the like of Japanese Patent Laid-Open No. 2008-75066 (cited with reference to all of them). .

The insulation is a member disposed between the inner liner and the carcass. Specifically, the insulation is a member shown in FIGS. 1-2 of JP-A-2008-150523 and FIG. 1 of JP-A-2007-269876.

The inner liner is a member formed so as to form a tire lumen surface, and by this member, the air permeation amount can be reduced and the tire internal pressure can be maintained. Specifically, it is a member shown in FIG. 1 of JP 2008-291091 A, FIGS. 1-2 of JP 2007-160980 A, and the like.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention.
In FIG. 1, the vertical direction is the tire radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. An alternate long and short dash line CL represents the equator plane of the pneumatic tire 2. The tread portion 4 of the pneumatic tire 2 includes an inner liner 14, an insulation 16, a carcass 10 (first ply 28, second ply 30), and a breaker 12 (inner layer 44, outer layer 46) in order from the inner side in the tire radial direction. A band 15 is provided. In one embodiment of the present invention, the rubber composition for insulation is used for the insulation 16 adjacent to the carcass 10 at the inside in the tire radial direction, and the rubber composition for inner liner is used for the insulation 16 in the tire radial direction. Used on the inner liner 14 adjacent on the inside.

In the present invention, the inner liner and the insulation are composed of a rubber composition for the inner liner and a rubber composition for the insulation, respectively.

Next, the rubber composition for inner liners and the rubber composition for insulation used in the present invention will be described.

(Rubber composition for inner liner)
The rubber composition for an inner liner includes a thermoplastic elastomer such as styrene-isobutylene-styrene block copolymer (SIBS) and a butyl rubber as a polymer component.
In the present specification, the polymer component means an elastomer component serving as a base material of the rubber composition, and specifically, a diene rubber used as a rubber component in the tire industry and an inner liner (rubber). It means a thermoplastic elastomer used as a base material for the composition.

The thermoplastic elastomer is not particularly limited, and examples thereof include styrene-isobutylene-styrene block copolymer (SIBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene block copolymer (SIB), and styrene. -Butadiene-styrene block copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene- Examples thereof include a styrene block copolymer (SEEPS) and a styrene-butadiene / butylene-styrene block copolymer (SBBS). Of these, SIBS is preferable.

SIBS isobutylene block provides excellent air retention. Therefore, when a rubber composition containing SIBS is used for the inner liner, a pneumatic tire excellent in air retention can be obtained.

Further, SIBS has excellent durability because its molecular structure other than aromatic is completely saturated, thereby preventing deterioration and hardening. Therefore, when a rubber composition containing SIBS is used for the inner liner, a pneumatic tire having excellent durability can be obtained.

The weight average molecular weight (Mw) of SIBS is preferably 50,000 to 400,000, more preferably 70,000 to 200,000. The effect of this invention is acquired more suitably as a weight average molecular weight is in the said range.
In addition, the weight average molecular weight (Mw) of SIBS is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ- manufactured by Tosoh Corporation). It can be determined by standard polystyrene conversion based on the measured value according to M).

Content of the styrene unit in SIBS becomes like this. Preferably it is 10-40 mass%, More preferably, it is 15-30 mass%. When the content of the styrene unit is within the above range, the effect of the present invention can be more suitably obtained.

SIBS preferably has a molar ratio of isobutylene units to styrene units (isobutylene units / styrene units) of 40/60 to 95/5 from the viewpoint of rubber elasticity of the copolymer. In SIBS, the degree of polymerization of each block is about 10,000 to 150,000 for the isobutylene block and 5,000 to 5,000 for the styrene block from the viewpoint of rubber elasticity and handling (becomes liquid when the degree of polymerization is less than 10,000). It is preferably about 30,000.
In the present specification, the content of isobutylene units SIBS, the content of styrene unit ^is calculated by H 1 -NMR measurement.

SIBS can be obtained by a general polymerization method of vinyl compounds. For example, it can be obtained by a living cationic polymerization method.

JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible, and polyisobutylene is obtained by using isobutylene and other compounds as vinyl compounds. It is disclosed that block copolymers of the system can be produced. In addition to this, methods for producing vinyl compound polymers by the living cation polymerization method are disclosed in, for example, US Pat. No. 4,946,899, US Pat. No. 5,219,948, JP-A-3-174403, and the like. Have been described.

As SIBS, for example, products such as Kaneka Corporation (SIBSTAR series, etc.) can be used.

The content of the thermoplastic elastomer (preferably SIBS) in 100% by mass of the polymer component is preferably 50% by mass or more, more preferably 60% by mass or more. By setting it to the lower limit or more, good air retainability and adhesiveness (particularly air retainability) tend to be obtained. The content is preferably 95% by mass or less. By setting it to the upper limit or less, good air retention and adhesiveness (particularly adhesiveness) tend to be obtained.

Examples of the butyl rubber include halogenated butyl rubber (X-IIR) such as brominated butyl rubber (BR-IIR) and chlorinated butyl rubber (Cl-IIR), and butyl rubber (IIR). These may be used alone or in combination of two or more. Among these, X-IIR such as Cl-IIR is preferable, and Cl-IIR is more preferable because the effects of the present invention can be more suitably obtained.

As the butyl rubber, for example, products such as ExxonMobil Co., Ltd., JSR Corporation, Japan Butyl Corporation, etc. can be used.

The content of butyl rubber in 100% by mass of the polymer component is preferably 5% by mass or more. By setting it to the lower limit or more, good air retention and adhesiveness (particularly adhesiveness) tend to be obtained. Moreover, this content becomes like this. Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less. By setting it to the upper limit or less, good air retention tends to be obtained.

Polymer components other than the thermoplastic elastomer and butyl rubber that can be used in the rubber composition for the inner liner are not particularly limited, and areoprene rubber such as natural rubber (NR) and isoprene rubber (IR), butadiene rubber (BR), Examples thereof include diene rubbers such as styrene butadiene rubber (SBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These may be used alone or in combination of two or more.

In the present specification, examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As the NR, for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20 and the like can be used. As IR, it is not specifically limited, For example, IR2200 etc. can use what is common in tire industry. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. Of these, NR is preferable.

The total content of butyl rubber and thermoplastic elastomer (preferably SIBS) in 100% by mass of the polymer component is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass.

Carbon rubber is preferably blended in the rubber composition for the inner liner. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 5 m ² / g or more, more preferably 10 m ² / g or more, and still more preferably 15 m ² / g or more. By setting the lower limit or more, good air retention and adhesiveness tend to be obtained. Further, the _N 2 SA is preferably from 300 meters ² / g or less, more preferably ^{150m 2 / g, 40m 2 /} g or less is more preferable. By making it below the upper limit, good air retention and adhesiveness tend to be obtained.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by JISK6217-2: 2001.

Carbon black has a dibutyl phthalate oil absorption (DBP) of preferably 5 ml / 100 g or more, more preferably 40 ml / 100 g or more, and still more preferably 70 ml / 100 g or more. By setting the lower limit or more, good air retention and adhesiveness tend to be obtained. The DBP is preferably 300 ml / 100 g or less, more preferably 200 ml / 100 g or less, still more preferably 120 ml / 100 g or less. By making it below the upper limit, good air retention and adhesiveness tend to be obtained.
In addition, DBP of carbon black is calculated | required by the measuring method of JISK6217-4: 2001.

Examples of carbon black include products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nikka Carbon Co., Ltd., Columbia Carbon Co., etc. Can be used.

When carbon black is contained, the content of carbon black is preferably 20 parts by mass or more, more preferably 30 parts by mass or more with respect to 100 parts by mass of the polymer component. The content is preferably 65 parts by mass or less. By setting the content of carbon black to the above content, better air retention and adhesion can be obtained. In addition, the occurrence of cracks during traveling can be suppressed, and good fuel efficiency can be obtained.

It is preferable that zinc oxide is blended in the rubber composition for the inner liner. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Conventionally known zinc oxide can be used, for example, Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd. Can be used.

When zinc oxide is contained, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more with respect to 100 parts by mass of the polymer component. The content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 2.5 parts by mass or less. By setting the content of zinc oxide to the above content, better air retention and adhesiveness can be obtained. Moreover, generation | occurrence | production of the crack at the time of driving | running | working can also be suppressed.

The rubber composition for the inner liner is preferably blended with sulfur. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Nihon Kiboshi Kogyo Co., Ltd., Hosoi Chemical Co., Ltd. can be used.

When sulfur is contained, the content of sulfur is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more with respect to 100 parts by mass of the polymer component. The content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, still more preferably 2.0 parts by mass or less, and still more preferably 1.5 parts by mass or less. By setting the content of sulfur to the above content, better air retention and adhesiveness can be obtained.

(Insulation rubber composition)
The rubber composition for insulation contains butyl rubber and isoprene rubber as polymer components.

The content of the butyl rubber in 100% by mass of the polymer component is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. By setting the lower limit or more, good air retention and adhesiveness tend to be obtained. Moreover, this content becomes like this. Preferably it is 90 mass% or less, More preferably, it is 85 mass% or less. By making it below the upper limit, good air retention and adhesiveness tend to be obtained.
The butyl rubber can be preferably used in the same manner as described above.

The content of isoprene-based rubber in 100% by mass of the polymer component is preferably 10% by mass or more, more preferably 15% by mass or more. By setting the lower limit or more, good air retention and adhesiveness tend to be obtained. The content is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. By making it below the upper limit, good air retention and adhesiveness tend to be obtained.
In addition, the isoprene-type rubber can use the thing similar to the above suitably in the same aspect.

The total content of butyl rubber and isoprene rubber in 100% by mass of the polymer component is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass.

The polymer components other than butyl rubber and isoprene rubber that can be used in the rubber composition for insulation are not particularly limited, but the same polymer components as those for the inner liner rubber composition can be suitably used in the same manner.

It is preferable that carbon black is blended in the rubber composition for insulation. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.
Moreover, it is preferable that both the rubber composition for inner liners and the rubber composition for insulation contain carbon black. Thereby, an adhesion interface is suitably reinforced and better adhesiveness is obtained.

Although it does not specifically limit as carbon black, The thing similar to the rubber composition for inner liners can be used conveniently in the same aspect.

When carbon black is contained, the carbon black content is preferably 50 parts by mass or more with respect to 100 parts by mass of the polymer component. The content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less. By setting the content of carbon black to the above content, better air retention and adhesion can be obtained. In addition, the occurrence of cracks during traveling can be suppressed, and good fuel efficiency can be obtained.

It is preferable that sulfur is blended in the rubber composition for insulation. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Although it does not specifically limit as sulfur, The thing similar to the rubber composition for inner liners can be used conveniently in the same aspect.

When sulfur is contained, the content of sulfur is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, and further preferably 0.8 parts by mass or more with respect to 100 parts by mass of the polymer component. is there. The content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, still more preferably 2.0 parts by mass or less, and particularly preferably 1.5 parts by mass or less. By setting the content of sulfur to the above content, better air retention and adhesiveness can be obtained.

It is preferable that zinc oxide is blended in the rubber composition for insulation. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Although it does not specifically limit as a zinc oxide, The thing similar to the rubber composition for inner liners can be used conveniently in the same aspect.

When zinc oxide is contained, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more with respect to 100 parts by mass of the polymer component. The content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 2.5 parts by mass or less. By setting the content of zinc oxide to the above content, better air retention and adhesiveness can be obtained. Moreover, generation | occurrence | production of the crack at the time of driving | running | working can also be suppressed.

(Rubber composition for inner liner, rubber composition for insulation)
It is preferable to add a vulcanization accelerator to the rubber composition for the inner liner and the rubber composition for the insulation. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N′-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfena De-based vulcanization accelerator; diphenylguanidine, it may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more. Among these, a thiazole vulcanization accelerator is preferable and di-2-benzothiazolyl disulfide is more preferable because the effects of the present invention can be more suitably obtained.

When the rubber composition for an inner liner and the rubber composition for an insulation contain a vulcanization accelerator, the content of the vulcanization accelerator is based on 100 parts by mass of the polymer component and 100 parts by mass of the polymer component. The amount is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more. The content is preferably 10 parts by mass or less, more preferably 3.0 parts by mass or less, and still more preferably 2.0 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

It is preferable to blend stearic acid into the rubber composition for the inner liner and the rubber composition for the insulation. Thereby, there exists a tendency for favorable air retainability and adhesiveness to be acquired.

A conventionally well-known thing can be used as a stearic acid, For example, products, such as NOF Corporation, NOF company, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba fatty acid company, can be used.

In the rubber composition for the inner liner and the rubber composition for the insulation, when stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 100 parts by mass with respect to the polymer component. 1.0 parts by mass or more. The content is preferably 10 parts by mass or less, more preferably 3.0 parts by mass or less, and still more preferably 2.0 parts by mass or less. Within the above numerical range, the effects of the present invention tend to be obtained satisfactorily.

You may mix | blend an anti-aging agent with the rubber composition for inner liners, and the rubber composition for insulation.

Examples of the antiaging agent include naphthylamine type antiaging agents such as phenyl-α-naphthylamine; diphenylamine type antiaging agents such as octylated diphenylamine and 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine; N -Isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, etc. P-phenylenediamine-based antioxidants; quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer; 2,6-di-t-butyl-4-methylphenol; Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3 ', 5'-di-t-butyl- '- hydroxyphenyl) propionate] bis methane, tris, and the like polyphenolic antioxidants. These may be used alone or in combination of two or more. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 More preferred is a polymer of 1,2-dihydroquinoline.

As the anti-aging agent, for example, products such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexis Co. can be used.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the anti-aging agent is contained, the content of the anti-aging agent is preferably 0.3 parts by mass or more with respect to 100 parts by mass of the polymer component. Preferably it is 0.5 mass part or more. The content is preferably 10 parts by mass or less, more preferably 3.0 parts by mass or less, and still more preferably 2.0 parts by mass or less.

You may mix | blend a silica with the rubber composition for inner liners, and the rubber composition for insulation.

Examples of the silica include dry process silica (anhydrous silica), wet process silica (hydrous silica), and wet process silica is preferred because it has many silanol groups. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 90 m ² / g or more, more preferably 120 m ² / g or more, and still more preferably 150 m ² / g or more. The N ₂ SA is preferably 400 m ² / g or less, more preferably 200 m ² / g or less, and still more preferably 180 m ² / g or less.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

Examples of silica that can be used include products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

In the rubber composition for an inner liner and the rubber composition for an insulation, when silica is contained, the content of silica is preferably 5 parts by mass or more, more preferably 30 parts by mass or more with respect to 100 parts by mass of the polymer component. It is. The content is preferably 200 parts by mass or less, more preferably 100 parts by mass or less.

In the rubber composition for an inner liner and the rubber composition for an insulation, the total content of carbon black and silica is preferably based on 100 parts by mass of the polymer component because the effects of the present invention can be obtained better. It is 20-250 mass parts, Preferably it is 40-120 mass parts, More preferably, it is 50-80 mass parts.

You may mix | blend a silane coupling agent with the rubber composition for inner liners, and the rubber composition for insulation.

The silane coupling agent is not particularly limited. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilyl ester) 3) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3 -Sulphides such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive NXT, NXT-Z, etc. mercapto, vinyltriethoxysilane, vinyl Vinyl type such as trimethoxysilane, amino type such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycid Glycidoxy such as cyclopropyltrimethoxysilane, nitro such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane Etc. These may be used alone or in combination of two or more.

Examples of the silane coupling agent that can be used include Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd., and Toray Dow Corning Co., Ltd.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the silane coupling agent is contained, the content of the silane coupling agent is preferably 3 parts by mass or more with respect to 100 parts by mass of silica, and 5 masses. Part or more is more preferable. There exists a tendency for the effect by having mix | blended the silane coupling agent as it is 3 mass parts or more to be acquired. The content is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. When the amount is 20 parts by mass or less, an effect commensurate with the blending amount is obtained, and good workability during kneading tends to be obtained.

You may mix | blend resin with the rubber composition for inner liners, and the rubber composition for insulation. Here, the resin corresponds to the polymer component.

The resin is not particularly limited as long as it is generally used in the tire industry, and examples thereof include coumarone indene resin, terpene resin, pt-butylphenol acetylene resin, and acrylic resin. These may be used alone or in combination of two or more.

Examples of the resin include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Arizona Chemical Co., Ltd., Nikko Chemical Co., Ltd. Products such as Nippon Shokubai, JX Energy Co., Ltd., Arakawa Chemical Co., Ltd., Taoka Chemical Co., Ltd. can be used.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the resin is contained, the content of the resin 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 polymer component. It is. The content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 15 parts by mass or less.

You may mix | blend oil with the rubber composition for inner liners, and the rubber composition for insulation.

Examples of the oil include process oil, vegetable oil and fat, or a mixture thereof. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more.

Examples of the oil include Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd. Etc. can be used.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the oil is contained, the content of the oil 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 polymer component. It is. The content is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and still more preferably 20 parts by mass or less. The oil content includes the amount of oil contained in rubber (oil-extended rubber).

A liquid diene polymer may be blended as a softening agent in the inner liner rubber composition and the insulation rubber composition.

The liquid diene polymer is a diene polymer in a liquid state at normal temperature (25 ° C.). The liquid diene polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 1.0 × 10 ^{3 to} 2.0 × 10 ⁵ measured by gel permeation chromatography (GPC), 3.0 It is more preferable that it is * 10 < ³ > -1.5 * 10 < ⁴ >.
Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene isoprene copolymer (liquid SIR), and the like. It is done. These may be used alone or in combination of two or more.
In the rubber composition for an inner liner and the rubber composition for an insulation, when the liquid diene polymer is contained, the liquid diene polymer is blended at 50 parts by mass or less with respect to 100 parts by mass of the polymer component, for example. The

You may mix | blend a wax with the rubber composition for inner liners, and the rubber composition for insulation.

The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers such as ethylene and propylene. These may be used alone or in combination of two or more.

As the wax, for example, products such as Ouchi Shinsei Chemical Co., Ltd., Nippon Seiwa Co., Ltd., Seiko Chemical Co., Ltd. can be used.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the wax is contained, the content of the wax is preferably 0.5 parts by mass or more, more preferably 1 part by mass with respect to 100 parts by mass of the polymer component. More than a part. Further, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less.

In addition to the above components, the rubber composition can contain additives commonly used in the tire industry, such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. Examples include fillers; processing aids such as plasticizers and lubricants; softeners other than oil and liquid diene polymers; vulcanizing agents other than sulfur (for example, organic crosslinking agents and organic peroxides);

Further, a plate-like inorganic filler may be blended with the rubber composition for the inner liner and the rubber composition for the insulation (particularly, the rubber composition for the inner liner). Thereby, better air retention is obtained.

Examples of the plate-like inorganic filler include clay, talc, bentonite, and montmorillonite. These may be used alone or in combination of two or more.

In the rubber composition for an inner liner and the rubber composition for an insulation, when the plate-like inorganic filler is contained, the content of the plate-like inorganic filler is preferably 5 to 85 mass with respect to 100 parts by mass of the polymer component. Parts, more preferably 10 to 70 parts by mass.

(Pneumatic tire)
The pneumatic tire of the present invention can be manufactured by a conventionally known method such as the following method.
First, after compounding (adding) components other than the vulcanizing agent and vulcanization accelerator into a rubber kneading apparatus such as a Banbury mixer and an open roll (base kneading step), the obtained kneaded product is further mixed By blending (adding) and kneading the vulcanizing agent and vulcanization accelerator, unvulcanized rubber compositions for the inner liner and for the insulation are prepared, respectively.

As kneading conditions, when additives other than the vulcanizing agent and the vulcanization accelerator are blended, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30 seconds. -30 minutes, preferably 1-30 minutes.
When blending a vulcanizing agent and a vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C.

Next, each unvulcanized rubber composition is extruded according to the shape of the inner liner and insulation. Then, they are bonded together with other tire members on a tire molding machine to produce an unvulcanized tire (= raw cover), and then the unvulcanized tire is heated and pressurized in the vulcanizer. Thus, a pneumatic tire can be manufactured.

In addition, for example, a method of pasting a rubber composition in a sheet shape into a predetermined shape, a method of charging the rubber composition into two or more extruders and forming two layers at the head outlet of the extruder, etc. According to a known method, a sheet made of an inner liner and an insulation may be produced, and then the sheet may be bonded together with other tire members on a tire molding machine to produce an unvulcanized tire.

In the pneumatic tire of the present invention, the thickness of the inner liner (thickness when unvulcanized) is preferably 0.1 to 5.0 mm, more preferably 0.3 to 2.0 mm. When the thickness of the inner liner is within the above range, the effects of the present invention can be more suitably obtained.
Here, the thickness of the inner liner means the thickness of the inner liner on the equator plane (the length in the tire radial direction).

In the pneumatic tire of the present invention, the insulation thickness (thickness when unvulcanized) is preferably 0.1 to 5.0 mm, more preferably 0.3 to 2.0 mm. The effect of this invention is acquired more suitably as the thickness of an insulation is in the said range.
Here, the thickness of the insulation means the thickness of the insulation on the equator plane (the length in the tire radial direction).

The pneumatic tire of the present invention can be suitably used for passenger car tires, large passenger car tires, large SUV tires, heavy duty tires such as trucks and buses, light truck tires, and motorcycle tires.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
Below, the various chemical | medical agents used by the Example and the comparative example are demonstrated collectively.
Natural rubber: Natural rubber Butyl rubber: Cl-IIR
Thermoplastic elastomer: styrene-isobutylene-styrene triblock copolymer (SIBS, weight average molecular weight: 100,000, styrene unit content: 25 mass%, Shore A hardness: 25)
Carbon black: carbon black (N ₂ SA: 27 m ² / g, DBP absorption: 87 ml / 100 g)
Anti-aging agent: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic manufactured by NOF Corporation Acid `` 椿 ''
Oil: Aroma oil Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Di-2-benzothiazolyl disulfide

<Examples and Comparative Examples>
(Rubber composition for inner liner, rubber composition for insulation)
In accordance with the contents shown in Tables 1 and 2, materials other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. It was. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition.

(Pneumatic tire)
Further, the obtained unvulcanized rubber composition for each inner liner and each rubber composition for insulation were extruded into the shape of each member according to Table 3, and other tires on a tire molding machine. An unvulcanized tire was formed by bonding together with the member, and press vulcanized for 10 minutes under the condition of 170 ° C. to produce a test tire (size: 195 / 65R15). In addition, the thickness in Table 3 means the thickness in an unvulcanized tire.

The following evaluation was performed using the obtained test tire. The evaluation results are shown in Table 3.

(Adhesiveness at the joint)
The test tire was put in a wet heat oven at 80 ° C. and a relative humidity of 95% without rim assembly and deteriorated for 4 weeks. Adhesiveness at the joint (inner liner and installation) when running a deteriorated test tire on a drum under a load overload condition of 140% of the maximum load (maximum air pressure condition) of JIS standard Peeling at the interface). The results were expressed as an index using Comparative Example 1 as a reference (100). It shows that it is excellent in the adhesiveness in the interface (especially joint part) of an inner liner and insulation, so that an index | exponent is large. When the index was 130 or more, it was judged to be good.

(Air retention)
The test tire was assembled on a JIS standard rim 15 × 6 JJ, sealed with an initial air pressure of 200 Kpa, left at room temperature for 90 days, and the rate of decrease in air pressure (% / month) was calculated. The results were expressed as an index using Comparative Example 1 as a reference (100). The larger the index, the better the air retention. When the index was 130 or more, it was judged to be good.

A pneumatic tire having a carcass, an insulation adjacent to the carcass in a tire radial inner side, and an inner liner adjacent to the insulation in a tire radial inner side, wherein the inner liner includes styrene-isobutylene-styrene It consists of a rubber composition for an inner liner containing a thermoplastic elastomer such as a block copolymer and a butyl rubber, and the insulation is composed of a rubber composition for an insulation containing a butyl rubber and an isoprene rubber. The pneumatic tires of the examples were excellent in air retention and adhesion at the interface between the inner liner and the insulation (particularly the joint portion).

In addition, by comparing the comparative examples 1, 5, 7 and the example 2, and comparing the comparative examples 1, 6, 7 and the example 3, the air retention is achieved by using the specific inner liner and the specific installation together. It was revealed that the property and adhesiveness can be improved synergistically.

2 Pneumatic tire 4 Tread 10 Carcass 12 Breaker 14 Inner liner 15 Band 16 Installation 28 First ply 30 Second ply 44 Inner layer 46 Outer layer

Claims (1)

A pneumatic tire having a carcass, an installation adjacent to the carcass in a tire radial inner side, and an inner liner adjacent to the installation in a tire radial inner side,
The inner liner comprises a rubber composition for an inner liner containing a thermoplastic elastomer and a butyl rubber,
The insulation is a pneumatic tire made of a rubber composition for insulation including butyl rubber and isoprene rubber.

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