JP6367793B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided with an inner liner, and more particularly, to a pneumatic tire with improved ultraviolet degradation resistance and oxidation degradation performance.

  In recent years, tires have been made lighter due to the strong social demand for low fuel consumption of vehicles, and among the tire members, the amount of air leakage from the inside of the pneumatic tire to the outside is arranged inside the tire. Even inner liners that have a function of reducing air pressure reduction and improving air permeation resistance have been reduced in weight. For this reason, a film made of a material including a thermoplastic resin that has excellent air permeation resistance and can reduce the thickness of the inner liner layer has been proposed instead of the conventionally used butyl rubber.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-136766), a thermoplastic resin film is disposed inside a carcass layer, and the distance in the tire radial direction from the plane connecting the cross-sectional centers of the carcass cords of the carcass layer is described. It has been reported that, when it is made as small as possible, the shear rigidity in the tire circumferential direction is improved by the thermoplastic resin film, and the braking performance at the time of sudden braking from high speed running can be improved. Patent Document 1 also describes that the thermoplastic resin film forms bellows-like irregularities along the surface of the carcass cord.

  However, tires are sometimes exposed to the outdoors during transportation or display at a store, and are subject to deterioration due to sunlight, that is, ultraviolet rays. For this reason, the thermoplastic resin may deteriorate and cracks may be formed inside the tire, giving the user the impression that the inside appearance is poor. Moreover, the tire interior space of a pneumatic tire is normally filled with air. When cracks enter the inside of the tire, oxygen contained in the filled air is lost. In addition, the oxygen penetrates into the tire component and oxidizes the tire component over time. Thereby, since a thermoplastic resin deteriorates, it causes deterioration of durability of a tire. In order to suppress such deterioration of the durability of the tire due to ultraviolet rays, Patent Document 2 (Japanese Patent Laid-Open No. 2012-254779) proposes adding an ultraviolet absorber or an antioxidant to the thermoplastic resin.

JP 2004-136766 A Japanese Patent Application Laid-Open No. 2012-254779

  The present invention is to prevent deterioration of thermoplastic resin due to ultraviolet rays or oxygen in a pneumatic tire provided with an inner liner, thereby preventing a decrease in rigidity of the thermoplastic resin, and thus preventing a decrease in braking performance. .

  The pneumatic tire according to the present invention includes an inner liner disposed inside the tire, and a carcass ply provided adjacent to the inner liner and having a cord embedded in a rubber layer. The inner liner includes a first layer having a first elastomer component including a styrene-isobutylene-styrene block copolymer, a first ultraviolet absorber, and a first antioxidant, a styrene-isoprene-styrene block copolymer, and styrene. -It is comprised with the polymer laminated body containing the 2nd elastomer component containing the at least one of an isobutylene block copolymer, the 2nd layer which has a 2nd ultraviolet absorber, and a 2nd antioxidant. The total blending amount of the first ultraviolet absorber and the first antioxidant is 0.5% by mass or more and 40% by mass or less with respect to the first elastomer component. The total blending amount of the second ultraviolet absorber and the second antioxidant is 0.5% by mass or more and 40% by mass or less with respect to the second elastomer component. The thickness of the first layer is from 0.05 mm to 0.6 mm, and the thickness of the second layer is from 0.01 mm to 0.3 mm. The second layer is disposed in contact with the rubber layer of the carcass ply. When the diameter of the cord is D, the distance L from the plane passing through the center of the cross section of the cord to the second layer is 0 or more and (1 + D / 2) mm or less.

  The total amount of the first ultraviolet absorber and the first antioxidant is preferably 2.0% by mass or more and 20% by mass or less with respect to the first elastomer component. The total amount of the second ultraviolet absorber and the second antioxidant is preferably 2.0% by mass or more and 20% by mass or less with respect to the second elastomer component.

  It is preferable that at least one of a styrene-isobutylene-styrene block copolymer and a SIBS-modified copolymer is blended in either the first layer or the second layer.

  Either the first layer or the second layer preferably contains a tackifier or polyisobutylene.

  The boundary surface between the polymer laminate and the rubber layer of the carcass ply preferably has an uneven shape.

  In the pneumatic tire according to the present invention, at least one of the ultraviolet absorber and the antioxidant is contained not only in the first layer constituting the inner liner but also in the second layer. Deterioration is prevented, thus preventing a reduction in braking performance.

It is a schematic sectional drawing of the right half of the pneumatic tire of this invention. It is a typical sectional view expanding and showing the neighborhood of a boundary of a carcass ply and an inner liner in a pneumatic tire concerning one embodiment of the present invention. It is a typical sectional view expanding and showing the neighborhood of a boundary of a carcass ply and an inner liner in a pneumatic tire concerning one embodiment of the present invention. It is typical sectional drawing of the inner liner which concerns on one embodiment of this invention. It is typical sectional drawing of the inner liner which concerns on one embodiment of this invention.

<Tire structure>
The pneumatic tire of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a right half of a pneumatic tire according to an embodiment of the present invention, which is typically used as a pneumatic tire for passenger cars. A pneumatic tire 1 shown in FIG. 1 includes a tread portion 2, sidewall portions 3 and bead portions 4 arranged so as to form a toroid shape from both ends of the tread portion 2. Further, a bead core 5 is embedded in the bead portion 4. Further, a carcass ply 6 provided from one bead portion 4 to the other bead portion 4 (not shown) and folded at both ends around the bead core 5 and on the outer side of the crown portion of the carcass ply 6. Are arranged with a belt layer 7 composed of at least two plies.

  The belt layer 7 usually intersects two plies made of steel cords or cords such as aramid fibers with respect to the tire circumferential direction so that the cords are usually at an angle of 5 to 30 °. Are arranged as follows. In addition, a topping rubber layer can be provided on both outer sides of the belt layer 7 to reduce peeling at both ends of the belt layer 7. The carcass ply 6 has cords made of organic fibers such as polyester, nylon, and aramid arranged at approximately 90 ° in the tire circumferential direction, and the bead core 5 has a region surrounded by the carcass ply 6 and its folded portion. A bead apex 8 extending from the upper end in the direction of the sidewall portion 3 is disposed.

  An inner liner 9 is disposed on the inner side in the tire radial direction of the carcass ply 6 from one bead portion 4 to the other bead portion 4 (not shown).

  FIG. 2 is a schematic cross-sectional view showing an enlarged vicinity of the boundary between the carcass ply and the inner liner in the pneumatic tire according to the embodiment of the present invention. The inner liner 9 according to the present invention is composed of a polymer laminate including a first layer IL1 and a second layer IL2. The second layer IL2 is in contact with the rubber layer 6a constituting the carcass ply 6 and forms a boundary surface S. The carcass ply 6 has a plurality of cords K embedded in a rubber layer 6a at regular intervals.

  Here, in the pneumatic tire of the present invention, when the diameter of the cord K is D, the surface passing through the cross-sectional center of the cord K (the surface formed by connecting the cross-sectional centers of the cords K) is second from the KC. The distance L to the layer IL2 (that is, the distance L is the distance from the surface KC passing through the cross-sectional center of the code K to the boundary surface S) is 0 or more and (1 + D / 2) mm or less.

  As described later, the second layer IL2 includes at least one of a styrene-isoprene-styrene block copolymer (hereinafter also referred to as “SIS”) and a styrene-isobutylene block copolymer (hereinafter also referred to as “SIB”). Including. SIS and SIB have higher rigidity than the rubber layer 6 a of the carcass ply 6. Therefore, by making the distance L as small as (1 + D / 2) mm or less, shear stress acts in the tire circumferential direction of the second layer IL2, and the shear rigidity in the tire circumferential direction is improved. As a result, it is possible to improve the steering stability during travel of the pneumatic tire. On the other hand, when the distance L is smaller than 0 mm, the restraining force between the cords K of the carcass ply 6 is reduced, the cord K interval is likely to fluctuate, and the rigidity in the tire circumferential direction is lowered. Note that the distance L is smaller than 0 mm means that the boundary surface S between the rubber layer 6a and the second layer IL2 constituting the carcass ply 6 is closer to the side wall portion 3 than the surface KC passing through the cross-sectional center of the cord K. Means to be located.

  FIG. 3 is an enlarged schematic sectional view showing the vicinity of the boundary between the carcass ply and the inner liner in a pneumatic tire according to another embodiment of the present invention. As shown in FIG. 3, when the second layer IL2 of the polymer laminate enters between the cord K and the cord K of the carcass ply 6, the boundary surface S between the second layer IL2 and the rubber layer 6a is uneven. The shape may be formed. In the embodiment shown in FIG. 3, the distance L from the surface KC passing through the cross-sectional center of the cord K to the boundary surface S between the rubber layer 6a and the second layer IL2 is substantially zero. With this configuration, the shear rigidity in the tire circumferential direction is improved, and as a result, the braking performance when the pneumatic tire is running can be improved. The distance L when the boundary surface S has an uneven shape means the average value of the shortest distance L ′ from the surface KC passing through the cross-sectional center of the cord K to the boundary surface S between the rubber layer 6a and the second layer IL2. To do.

<Inner liner>
In the present invention, the inner liner is composed of a polymer laminate including a first layer disposed inside the tire and a second layer disposed so as to contact the rubber layer 6a of the carcass ply 6. The first layer contains both the first UV absorber and the first antioxidant, and the second layer contains both the second UV absorber and the second antioxidant. Therefore, a pneumatic tire excellent in braking performance can be provided.

[First layer]
The first layer has a first elastomer component containing a styrene-isobutylene-styrene block copolymer (hereinafter also referred to as “SIBS”), a first ultraviolet absorber, and a first antioxidant.

(1) First Elastomer Component The first elastomer component contains a styrene-isobutylene-styrene triblock copolymer (SIBS). Here, SIBS includes an isobutylene block in the molecular chain. Therefore, the polymer film made of SIBS has excellent air permeation resistance. Therefore, a pneumatic tire excellent in air permeation resistance can be obtained by using the first layer containing SIBS for the inner liner.

  As described above, a pneumatic tire having excellent air permeation resistance can be obtained by using the first layer containing SIBS for the inner liner. Therefore, it is not necessary to use a high specific gravity halogenated rubber which has been conventionally used for imparting air permeation resistance such as halogenated butyl rubber. Further, even when a high specific gravity halogenated rubber is used, the amount of use can be reduced. From these things, since the weight of the tire can be reduced, the effect of improving the fuel efficiency can be obtained.

  Further, since SIBS is saturated in its molecular structure except for an aromatic ring, it is hard to be cured even when it is deteriorated and has excellent durability. Therefore, when the first layer containing SIBS is used for the inner liner, a pneumatic tire having excellent durability can be obtained.

  The molecular weight of SIBS is not particularly limited. However, from the viewpoints of rubber elasticity, fluidity of SIBS, moldability to inner liner, etc., the mass average molecular weight of SIBS by GPC measurement is preferably 50,000 or more and 400,000 or less. If the mass average molecular weight of SIBS as measured by GPC is less than 50000, rubber elasticity, tensile strength and tensile elongation of SIBS may be reduced. Moreover, when the mass average molecular weight of SIBS by GPC measurement exceeds 400,000, there exists a possibility that the moldability (extrusion processability etc.) to an inner liner may fall by the fall of the fluidity | liquidity of SIBS. The content of the styrene component in SIBS is preferably 10 to 40% by mass, more preferably 10 to 30% by mass, from the viewpoint of improving the air permeability and durability of the tire. More preferably, it is 14-23 mass%. The molar ratio of isobutylene component and styrene component (isobutylene / styrene) constituting SIBS is preferably 40/60 to 95/5 from the viewpoint of rubber elasticity of SIBS.

  In SIBS, from the viewpoint of rubber elasticity and handleability of SIBS (the degree of polymerization may be liquid when the degree of polymerization is less than 10,000), the degree of polymerization of each block in the molecular chain is about 10,000 to 150,000 for the isobutylene block. It is preferable that the styrene block is about 5000 to 30000.

  SIBS can be obtained by a general vinyl compound polymerization method such as a living cationic polymerization method. For example, JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible, and isobutylene as a vinyl compound and other compounds are used as living compounds. It is disclosed that a polyisobutylene block copolymer can be produced by cationic polymerization. In addition to this, a method for producing a vinyl compound polymer by a living cationic polymerization method is disclosed in, for example, US Pat. No. 4,946,899, US Pat. No. 5,219,948, and Japanese Patent Laid-Open No. 3-174403. It is described in.

  Since SIBS has no double bond other than an aromatic ring in the molecule, it is more stable to ultraviolet rays than a polymer having a double bond in the molecule (for example, polybutadiene), and is therefore weather resistant. Good properties. In addition, the refractive index (nD) at 20 ° C. of light having a wavelength of 589 nm, despite having no double bond other than an aromatic ring in the molecule and being a saturated rubbery polymer, is a polymer handbook. [1989: Wiley (Polymer Handbook, Willy, 1989)], it is 1.506. This is significantly higher than other saturated rubbery polymers (eg ethylene-butene copolymers).

  The first elastomer component may be made of SIBS, but may contain SIBS and a SIBS-modified copolymer, or may be made of a SIBS-modified copolymer. The SIBS-modified copolymer is obtained by modifying the styrene block portion of SIBS with an acid chloride or acid anhydride having an unsaturated bond. Here, examples of the acid chloride include methacrylic acid chloride, methacrylic acid bromide, methacrylic acid iodide, acrylic acid chloride, acrylic acid bromide, acrylic acid iodide, crotonyl acid chloride, and crotonyl acid bromide. In particular, methacrylic acid chloride and acrylic acid chloride are suitable. Examples of the acid anhydride include acetic anhydride, maleic anhydride, and phthalic anhydride, and acetic anhydride is particularly preferable. Two or more of these compounds can be used in combination. Since the unsaturated group is introduced into SIBS by such modification, crosslinking using a crosslinking agent can be made possible.

  The SIBS-modified copolymer is preferably blended in an amount of 10% by mass or more and 100% by mass, more preferably 30% by mass or more and 100% by mass in the first elastomer component. When the blending amount of the SIBS-modified copolymer is less than 10% by mass of the first elastomer component, vulcanization adhesion between the second layer and the carcass ply rubber may not be sufficient.

  In the SIBS-modified copolymer, the acid chloride and the acid anhydride are preferably contained in an amount of 1% by mass or more, more preferably 5% by mass or more, and 30% by mass or less. More preferably.

  As a method of crosslinking the SIBS-modified copolymer, a conventional method can be used. For example, thermal crosslinking by heating or crosslinking by a crosslinking agent can be performed. Here, as the crosslinking agent, organic peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane and the like can be used. . The organic peroxide is preferably blended in an amount of 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the first elastomer component. In addition, polyfunctional vinyl monomer (for example, divinylbenzene), triallyl cyanurate, or polyfunctional methacrylate monomer (for example, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylol propane tri (Methacrylate or allyl methacrylate) can also be used in combination as a crosslinking agent. In this case, it can be expected to improve the flex cracking property of the composition after crosslinking.

  Since the SIBS-modified copolymer contains an isobutylene block, the film made of the SIBS-modified copolymer has excellent air permeation resistance. In addition, in the SIBS-modified copolymer, unsaturated groups are introduced into SIBS, so that thermal crosslinking and crosslinking with a crosslinking agent are possible, and basic properties such as tensile strength, elongation at break and permanent strain, as well as flex crack properties. In addition, the air permeation resistance is improved and the properties as an inner liner are improved.

  A pneumatic tire having excellent air permeation resistance can also be obtained by using the first layer containing the SIBS-modified copolymer for the inner liner. Therefore, as in the case where the first layer containing SIBS is used for the inner liner, the weight of the tire can be reduced, so that the effect of improving fuel efficiency can be obtained. The same can be said for the molecular weight of the SIBS-modified copolymer.

  The SIBS-modified copolymer can be obtained, for example, by the following method. After placing the styrene-isobutylene-styrene block copolymer in a separable flask, the inside of the polymerization vessel is purged with nitrogen. Thereafter, an organic solvent (for example, n-hexane and butyl chloride) dried with molecular sieves is added, and methacrylic acid chloride is further added. Finally, aluminum trichloride is added and reacted while stirring the solution. After a certain time from the start of the reaction, a predetermined amount of water is added to the reaction solution and stirred to terminate the reaction. The reaction solution is washed with a large amount of water several times or more, further slowly dropped into a large amount of a mixed solvent of methanol and acetone to precipitate a polymer, and the obtained polymer is vacuum dried. A method for producing a SIBS-modified copolymer is disclosed in, for example, Japanese Patent No. 4510005 (Japanese Patent Laid-Open No. 2002-226667).

(2) 1st ultraviolet absorber A 1st ultraviolet absorber absorbs the light of the ultraviolet region which has a wavelength of 290 nm or more, and prevents degradation of the molecular chain of a high molecular compound. For example, benzophenone-based, salicylate-based, and benzotriazole-based ultraviolet absorbers absorb ultraviolet light having a wavelength of 320 nm to 350 nm, which is most susceptible to degradation by polymer compounds, and convert light in this wavelength region into vibration energy or thermal energy. It has a function of preventing absorption into a polymer compound by conversion. In particular, benzotriazole ultraviolet absorbers can absorb a wide range of ultraviolet light. Here, it is as follows if the 1st ultraviolet absorber is illustrated.

[Benzotriazole UV absorber]
TINUVIN P / FL (manufactured by BASF, molecular weight 225, melting point 128-132 ° C., maximum absorption wavelength 341 nm) (2- (2-hydroxy-benzotriazol-2-yl) -p-cresol)
TINUVIN 234 (manufactured by BASF, molecular weight 447.6, melting point 137 to 141 ° C., maximum absorption wavelength 343 nm) (2- [2-hydroxy-3,5-bis (α, α′dimethylbenzyl) phenyl] -2H-benzo Triazole)
TINUVIN 326 / FL (manufactured by BASF, molecular weight 315.8, melting point 138-141 ° C., maximum absorption wavelength 353 nm), ADK STAB LA-36 (manufactured by ADEKA) (2- (2′-hydroxy-3′-tert) -Butyl-5'-methylphenyl) -5-chlorobenzotriazole)
TINUVIN 237 (manufactured by BASF, molecular weight 338.4, melting point 139-144 ° C., maximum absorption wavelength 359 nm) (2,4-di-t-butyl-6- (5-chlorobenzotriazol-2-yl-) phenol)
TINUVIN 328 (BASF, molecular weight 351.5, melting point 80-88 ° C., maximum absorption wavelength 347 nm) (2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole) TINUVIN 329 / FL ( BASF, molecular weight 323, melting point 103-105 ° C., maximum absorption wavelength 343 nm) (2- (2-hydroxy-benzotriazol-2-yl) -4-tert-octylphenol).

[Liquid UV absorber]
TINUVIN 213 (BASF, melting point −40 ° C., maximum absorption wavelength 344 nm) (methyl 5- (2-hydroxy-benzotriazol-2-yl) -4-hydroxy-3-tert-butylbenzenepropanoate)
TINUVIN 571 (manufactured by BASF, molecular weight 393.6, melting point −56 ° C., maximum absorption wavelength 343 nm) (2- (2-hydroxy-benzotriazol-2-yl) -4-methyl-6-dodecylphenol).

[Triazine UV absorber]
TINUVIN 1577FF (manufactured by BASF, molecular weight 425, melting point 148 ° C., maximum absorption wavelength 274 nm) (2- [4,6-diphenyl-1,3,5-triazin-2-yl] -5- (hexyloxy) phenol) .

[Benzophenone UV absorber]
CHIMASSORB 81 / FL (BASF, molecular weight 326.4, melting point 48-49 ° C.) (2-hydroxy-4- (octyloxy) benzophenone).

[Benzoate UV absorber]
TINUVIN 120 (BASF, molecular weight 438.7, melting point 192 to 197 ° C., maximum absorption wavelength 265 nm) (2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate) .

[Hindered amine stabilizer]
CHIMASSORB 2020 FDL (BASF, molecular weight 2600-3400, melting point 130-136 ° C.) (dibutylamine 1,3,5-triazine / N, N-bis (2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine / N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate)
CHIMASSORB 944 FDL (BASF, molecular weight 2000-3100, melting point 100-135 ° C.) (poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2, 4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl) imino}])
TINUVIN 622 LD (manufactured by BASF, molecular weight 3100 to 4000, melting point 55 to 70 ° C.) (butanedioic acid 1- [2- (4-hydroxy-2,2,6,6-tetramethylpiperidino) ethyl])
TINUVIN 144 (manufactured by BASF, molecular weight 685, melting point 146-150 ° C.) (2-butyl-2- [3,5-di (tert-butyl) -4-hydroxybenzyl] malonic acid bis (1,2,2, 6,6-pentamethyl-4-piperidyl)
TINUVIN 292 (BASF, molecular weight 509) (bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate))
TINUVIN 770 DF (manufactured by BASF, molecular weight 481, melting point 81-85 ° C.) (bis (2,2,6,6-tetramethylpiperidin-4-yl) sebacate).

  As a 1st ultraviolet absorber, any 1 type of the said ultraviolet absorber may be used, and 2 or more types of the said ultraviolet absorber may be mixed and used.

(3) First Antioxidant The first antioxidant functions as a radical scavenger and can prevent deterioration of the molecular chain of the polymer by mainly capturing carbon radicals. The first antioxidant is exemplified below.

[Hindered phenolic antioxidants]
IRGANOX 1010 (manufactured by BASF), Adeka Stub AO-60 (manufactured by ADEKA), Sumilyzer BP-101 (manufactured by Sumitomo Chemical Co., Ltd.) (pentaerythrityl tetrakis [3- (3,505-di-t-butyl- 4-hydroxyphenyl) propionate])
IRGANOX 1035 (manufactured by BASF) (2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate])
IRGANOX 1076 (manufactured by BASF) (octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate)
IRGANOX 1098 (manufactured by BASF) (N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide))
IRGANOX 1135 (manufactured by BASF) (isooctyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate])
IRGANOX1330 (manufactured by BASF) (1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene)
IRGANOX1726 (manufactured by BASF) (4,6-bis (dodecylthiomethyl) -O-cresol)
IRGANOX1425 (manufactured by BASF) (bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium (50%), polyethylene wax (50%))
IRGANOX1520 (manufactured by BASF) (2,4-bis [(octylthio) methyl] -O-cresol)
IRGANOX245 (manufactured by BASF) (triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate])
IRGANOX259 (manufactured by BASF) (1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate])
IRGANOX 3114 (manufactured by BASF) (Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate)
IRGANOX5057 (BASF) (octylated diphenylamine)
IRGANOX565 (manufactured by BASF) (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine)
Syanox CY1790 (manufactured by Sun Chemical Co., Ltd.) (1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid)
ADK STAB AO-40 (manufactured by ADEKA Co., Ltd.), Sumilycer BBM (manufactured by Sumitomo Chemical Co., Ltd.) (4,4′-butylidenebis (3-methyl-6-tert-butylphenol))
ADK STAB AO-50 (manufactured by ADEKA), Sumilyzer BP-76 (manufactured by Sumitomo Chemical Co., Ltd.) (stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate)
ADK STAB AO-80 (manufactured by ADEKA), Sumilyzer GA-80 (manufactured by Sumitomo Chemical Co., Ltd.) (3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4) -Hydroxy-5-methylfienyl) propionyloxy] ethyl] 2,4,8,10-tetraoxaspiro [5,5] -undecane).

[Phosphorus antioxidant]
Phosphorous antioxidants are used as peroxide decomposing agents, and are excellent in the antioxidant function during thermal processing molding.
IRGAFOS12 (BASF, molecular weight 1462.9) (6,6 ′, 6 ″-[nitrilotris (ethyleneoxy)] tris (2,4,8,10-tetra-tert-butylbenzo [d, f] [1 , 3,2] dioxaphosphepine)))
IRGAFOS38 (manufactured by BASF, molecular weight 514) (ethylbisphosphite (2,4-di-tert-butyl-6-methylphenyl))
IRGAFOS168 (BASF, molecular weight 646)
ADK STAB 2112 (made by ADEKA Corporation)
Sumilyzer P-16 (manufactured by Sumitomo Chemical Co., Ltd.) (Tris (2,4-di-t-butylphenyl) phosphite)
ADK STAB PEP-8 (manufactured by ADEKA) (distearyl pentaerythritol diphosphite)
ADK STAB PEP-36 (manufactured by ADEKA) (cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite).

[Hydroxylamine type]
IRGASTAB FS 042 (manufactured by BASF) (N, N-dioctadecylhydroxylamine).

[Hindered phenol / phosphorus mixed antioxidant]
45 IRGANOX B 225 (BASF) (IRGAFOS168: IRGANOX1010 = 1: 1)
IRGANOX215 (BASF) (IRGAFOS168: IRGANOX1010 = 2: 1)
IRGANOX220 (manufactured by BASF) (IRGAFOS168: IRGANOX1010 = 3: 1)
IRGANOX921 (manufactured by BASF) (IRGAFOS168: IRGANOX1076 = 2: 1).

  As the first antioxidant, any one of the above antioxidants may be used, or two or more of the above antioxidants may be mixed and used.

(4) Total blending amount of the first UV absorber and the first antioxidant The total blending amount of the first UV absorber and the first antioxidant is 0.5% by mass or more and 40% by mass with respect to the first elastomer component. % Or less. If the total blending amount is less than 0.5% by mass with respect to the first elastomer component, the effect expected by the addition of the first ultraviolet absorber and the first antioxidant may not be sufficiently exhibited. When this total compounding quantity exceeds 40 mass% with respect to a 1st elastomer component, the fall of the original function of a 1st layer may be caused. Preferably, the total blending amount is 2.0% by mass or more and 20% by mass or less with respect to the first elastomer component.

  One or more of the above listed first ultraviolet absorbers can be used in combination with one or more of the above listed first antioxidants. For example, it is preferable to use a combination of a benzotriazole ultraviolet absorber and a hindered phenol antioxidant.

(5) Oxygen absorber In this invention, antioxidant is the concept containing an oxygen absorber. As the oxygen absorbent, a general oxygen absorbent having the ability to capture oxygen in the air can be used, for example, iron powder oxygen absorption that absorbs oxygen in the air using an oxidation reaction of iron powder. You can give the agent. At this time, it is usually preferable to use 0.1 to 50 parts by mass of a halide in combination with 100 parts by mass of iron powder having a surface area of 0.5 m ² / g or more. The halide may be an alkali metal chloride, bromide or iodide (eg sodium chloride or sodium bromide), or an alkaline earth metal chloride, bromide or iodide (eg calcium chloride or chloride). Magnesium) and the like. Iron powder and a halide may be mixed, or the surface of the iron powder may be coated with a halide. As the oxygen absorbent used in the present invention, an oxygen absorbent obtained by further promoting the oxidation of iron by oxygen by further combining porous particles such as zeolite with water impregnated may be used. In particular, hindered phenolic antioxidants as radical trapping agents for carbon radicals are preferred.

(6) Tackifier It is preferable that a tackifier is blended in the first layer. Thereby, the external appearance of a pneumatic tire can be improved by prevention of air-in. In addition, tire characteristics such as durability, driving stability during traveling, air permeation resistance (air blocking property), and rolling resistance can be further improved. In particular, by improving the adhesive strength between the first layer and the second layer and / or the adhesive strength between the second layer and the carcass ply, it is possible to improve driving stability during traveling. Moreover, the addition of the tackifier further improves the adhesive strength of the first elastomer component containing SIBS, and further improves the adhesive strength of the first layer. Thereby, problems such as the rubber composition layer forming the first layer falling off during tire molding are less likely to occur, and the molding processability of the pneumatic tire can be further improved.

  When tackifier is mix | blended with the 1st layer, it is preferable that 1-100 mass parts is mix | blended with respect to 100 mass parts of SIBS, and 1-50 mass parts is mix | blended. More preferred. If the compounding amount of the tackifier is less than 1 part by mass with respect to 100 parts by mass of SIBS, the effect obtained by blending the tackifier may not be sufficiently obtained. On the other hand, when the compounding amount of the tackifier exceeds 100 parts by mass with respect to 100 parts by mass of SIBS, the steering stability during running or the air permeation resistance tends to decrease.

Here, “tackifier” refers to an additive for enhancing the tackiness of the rubber composition forming the inner liner. The mass average molecular weight of the tackifier by GPC measurement is preferably 1 × 10 ² to 1 × 10 ⁶ . When the mass average molecular weight of the tackifier by GPC measurement is less than 1 × 10 ² , the viscosity of the tackifier is too low, which is disadvantageous in terms of moldability to the inner liner. On the other hand, when the mass average molecular weight of the tackifier by GPC measurement exceeds 1 × 10 ⁶ , the tackiness tends to be insufficient to the first layer. The softening point of the tackifier is preferably in the range of 50 ° C to 150 ° C. When the softening point of the tackifier is less than 50 ° C., the rubber hardness of the tire is greatly lowered, and the steering stability tends to be lowered. On the other hand, when the softening point of the tackifier exceeds 150 ° C, the tackifying effect tends to be insufficient. The softening point is measured using a differential scanning calorimeter (“DSC 2910” manufactured by TA Instruments Japan Co., Ltd.). Examples of the tackifier that can be used in the present invention include the following.

[C9 petroleum resin]
C9 petroleum resin is obtained by polymerizing the C5 to C9 fraction (mainly C9 fraction), which is the remainder obtained by removing useful compounds such as ethylene, propylene or butadiene from the thermal decomposition product of naphtha in a mixed state. Aromatic petroleum resin. All are trade names, Alcon P70, P90, P100, P115, P125, P140, M90, M100, M115, M135 (all Arakawa Chemical Industries, Ltd., softening point 70-145 ° C.); , P100, P125, P140 (all manufactured by Idemitsu Petrochemical Co., Ltd., aromatic copolymer hydrogenated petroleum resin, softening point 100-140 ° C., mass average molecular weight 700-900, bromine number 2.0-6.0 g) / 100 g); Petcoal XL (manufactured by Tosoh Corporation).

[C5 petroleum resin]
C5 petroleum resin is obtained by polymerizing a C4 to C5 fraction (mainly C5 fraction), which is a residue obtained by removing a useful compound such as ethylene, propylene or butadiene from a thermal decomposition product of naphtha in a mixed state. It is an aliphatic petroleum resin. All are trade names: Highlets G100 (Mitsui Petrochemical Co., Ltd., softening point 100 ° C.); Marcarets T100AS (Maruzen Oil Co., Ltd., softening point 100 ° C.); Escorez 1102 (Tonex Corp., softening point) 110 ° C.).

[Terpene resin]
All are trade names, YS Resin PX800N, PX1000, PX1150, PX1250, PXN1150N, Clearon P85, P105, P115, P125, P135, P150, M105, M115, K100 (all from Yashara Chemical Co., Ltd., softening point 75-160 ° C).

[Aromatic modified terpene resin]
All are trade names, such as YS resin TO85, TO105, TO115, TO125 (all manufactured by Yashara Chemical Co., Ltd., softening point 80-130 ° C.).

[Terpene phenol resin]
All are trade names, Tamanoru 803L, 901 (Arakawa Chemical Industries, softening point 120-160 ° C.); YS Polystar U115, U130, T80, T100, T115, T130, T145, T160 (all Yashara Chemical Co., Ltd. ), Softening point 75-165 ° C.).

[Coumarone resin]
Coumarone resin (manufactured by Kobe Oil Chemical Co., Ltd.) having a softening point of 90 ° C. is available.

[Coumaron Inden Oil]
There is a trade name of 15E (manufactured by Kobe Oil Chemical Co., Ltd., pour point 15 ° C.).

[Rosin ester]
All are trade names, Ester gum AAL, A, AAV, 105, AT, H, HP, HD (all Arakawa Chemical Industries, softening point 68-110 ° C.); Harrier Star TF, S, C, DS70L, DS90, DS130 (all manufactured by Harima Kasei Co., Ltd., softening point 68-138 ° C.) and the like.

[Hydrogenated rosin ester]
All are trade names and include Superesters A75, A100, A115, and A125 (all manufactured by Arakawa Chemical Industries, Ltd., softening point 70 to 130 ° C.).

[Alkylphenol resin]
There are Tamanoru 510 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 75 to 95 ° C.) under the trade name.

[DCPD]
Under the trade name, there is Escoretz 5300 (manufactured by Tonex Co., Ltd., softening point 105 ° C.).

  Among these, a fully hydrogenated petroleum resin of C9 petroleum resin is preferable. The completely hydrogenated petroleum resin of C9 petroleum resin has good compatibility with SIBS constituting the first layer, and has a high effect of improving the adhesive strength of the first layer. The effect of improving the adhesive strength and / or the adhesive strength between the second layer and the carcass ply is high.

  When the tackifier is blended in the first layer, the second elastomer component of the second layer is styrene-isoprene-styrene triblock copolymer (SIS) or styrene-isobutylene diblock copolymer (SIB) 20 It is preferable to be comprised from -90 mass% and 10-80 mass% of styrene-isobutylene-styrene triblock copolymers (SIBS). By using SIBS together with SIS or SIB as the second elastomer component, the effect of the tackifier can be sufficiently obtained. However, when the content of SIBS in the second elastomer component exceeds 80% by mass, the adhesive strength between the second layer and the carcass ply tends to decrease. Moreover, it exists in the tendency for the effect of a tackifier to fully not be acquired as content of SIBS in a 2nd elastomer component is less than 10 mass%.

(7) Polyisobutylene It is preferable that polyisobutylene is blended in the first layer. Thereby, adhesiveness increases and workability improves.

  When polyisobutylene is blended in the first layer, the polyisobutylene is preferably blended in an amount of 3 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of SIBS. . If the blending amount of polyisobutylene is less than 3 parts by weight with respect to 100 parts by weight of SIBS, the effect obtained by blending polyisobutylene may not be sufficiently obtained. On the other hand, when the compounding amount of polyisobutylene exceeds 20 parts by mass with respect to 100 parts by mass of SIBS, the fracture strength may be lowered.

  The molecular weight of polyisobutylene is not particularly limited, but is preferably 9000 or more and 60000 or less, and more preferably 12000 or more and 51000 or less, from the viewpoint of achieving both improvement in adhesion and prevention of reduction in fracture strength.

(8) Thickness of the first layer The thickness of the first layer including SIBS (T1 in FIG. 2) is 0.05 to 0.6 mm. When the thickness T1 of the first layer is less than 0.05 mm, the vulcanization of the raw tire in which the polymer laminate is applied to the inner liner causes the first layer to be broken by the press pressure, and the resulting tire has an air leak. Phenomena may occur. On the other hand, if the thickness T1 of the first layer exceeds 0.6 mm, the tire mass increases and the fuel efficiency performance decreases. The thickness T1 of the first layer is preferably 0.05 to 0.4 mm.

  The first layer can be obtained according to a usual method for forming a thermoplastic resin or a thermoplastic elastomer into a film. For example, a first rubber composition containing a first elastomer component, a first ultraviolet absorber, and a first antioxidant. The product can be obtained by forming into a film by extrusion molding or calendering. The first layer may further contain other additives such as a reinforcing agent, a vulcanizing agent, a vulcanization accelerator, various oils, an anti-aging agent, a softening agent, a plasticizer, or a coupling agent.

[Second layer]
The second layer includes a second elastomer component containing at least one of styrene-isoprene-styrene block copolymer (SIS) and styrene-isobutylene block copolymer (SIB), a second ultraviolet absorber, and a second antioxidant. And having an agent.

(1) Second Elastomer Component The second elastomer component contains at least one of SIS and SIB. Since the isoprene block of SIS and the isobutylene block of SIB are soft segments, the polymer film containing SIS or SIB tends to be vulcanized and bonded to the rubber component. Therefore, by using the inner liner provided with the second layer containing SIS or SIB, a pneumatic tire excellent in adhesive strength between the inner liner and the rubber layer of the carcass ply can be obtained. Thereby, durability of a pneumatic tire and steering stability at the time of driving | running | working can be improved.

  The molecular weight of SIS is not particularly limited. However, from the viewpoints of rubber elasticity of SIS and molding processability to the inner liner, the mass average molecular weight of SIS by GPC measurement is preferably 100,000 or more and 290000 or less. When the mass average molecular weight of SIS by GPC measurement is less than 100,000, rubber elasticity and tensile strength of SIS may be reduced. Moreover, when the mass average molecular weight of SIS by GPC measurement exceeds 290000, there exists a possibility that the molding processability (extrusion processability etc.) to an inner liner may fall by the fall of the fluidity | liquidity of SIS. The content of the styrene component in the SIS is 10 to 30% by mass from the viewpoints of SIS tackiness, SIS rubber elasticity, adhesion strength of the second layer to the first layer and adhesion strength of the second layer to the carcass ply. Preferably there is.

  The degree of polymerization of each block constituting the SIS is preferably about 500 to 5000 for the isoprene block and preferably about 50 to 1500 for the styrene block from the viewpoint of rubber elasticity and handleability of the SIS.

  The SIS can be obtained by a general vinyl compound polymerization method such as a living cationic polymerization method.

  It is preferable to use a linear SIB from the viewpoint of rubber elasticity, adhesive strength of the second layer to the first layer, and adhesive strength of the second layer to the carcass ply. The molecular weight of SIB is not particularly limited. However, from the viewpoint of rubber elasticity of SIB and moldability to the inner liner, the mass average molecular weight of SIB by GPC measurement is preferably 40000 to 120,000. If the mass average molecular weight of SIB by GPC measurement is less than 40000, rubber elasticity and tensile strength of SIB may be reduced. Moreover, when the mass average molecular weight of SIB by GPC measurement exceeds 120,000, there exists a possibility that the moldability (extrusion processability etc.) to an inner liner may fall by the fall of the fluidity | liquidity of SIB. The content of the styrene component in the SIB is 10 to 35% by mass from the viewpoints of the adhesiveness of the SIB, the rubber elasticity of the SIB, the adhesive strength of the second layer to the first layer, and the adhesive strength of the second layer to the carcass ply. Preferably there is.

  The degree of polymerization of each block constituting the SIB is preferably about 300 to 3000 for the isobutylene block and about 10 to 1500 for the styrene block from the viewpoint of rubber elasticity and handleability of the SIB.

  SIB can be obtained by a general vinyl compound polymerization method such as a living cationic polymerization method. For example, in International Publication No. 2005/033035, methylcyclohexane, n-butyl chloride and cumyl chloride are added to a stirrer, cooled to −70 ° C., reacted for 2 hours, and then a large amount of methanol is added. A method is disclosed in which the reaction is stopped and vacuum dried at 60 ° C. to obtain SIB.

  The second elastomer component is preferably obtained by mixing each of SIS and SIB at an arbitrary ratio. In this case, the second layer may have a single layer structure including both SIS and SIB, or may have a multilayer structure including a layer including SIS and a layer including SIB layer.

  The second elastomer component is styrene-isoprene-butadiene-styrene copolymer (SIBS), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), styrene- One or more selected from the group consisting of ethylene / ethylene / propylene / styrene copolymer (SEEPS), styrene / butadiene / butylene / styrene copolymer (SBBS), and those obtained by introducing an epoxy group into these thermoplastic elastomers. The thermoplastic elastomer may be included. The same applies to the first layer. Examples of the thermoplastic elastomer having an epoxy group include an epoxy-modified styrene-butadiene-styrene copolymer (specific examples include “epoefriend A1020” manufactured by Epoxidized SBS Daicel Chemical Industries, Ltd., mass average molecular weight: 100,000). , Epoxy equivalent: 500, etc.).

(2) Second ultraviolet absorber The second ultraviolet absorber, like the first ultraviolet absorber, absorbs light in the ultraviolet region having a wavelength of 290 nm or more and prevents the molecular chain of the polymer compound from deteriorating. As the second ultraviolet absorber, the materials listed as specific examples of the first ultraviolet absorber can be used without particular limitation, and any one of the materials listed as specific examples of the first ultraviolet absorber is used. Alternatively, two or more kinds may be mixed and used. The second ultraviolet absorber blended in the second layer may be the same as the first ultraviolet absorber blended in the first layer, or different from the first ultraviolet absorber blended in the first layer. May be.

(3) Second Antioxidant Similar to the first antioxidant, the second antioxidant functions as a radical scavenger and can prevent deterioration of the molecular chain of the polymer by mainly capturing carbon radicals. As the second antioxidant, the materials listed as specific examples of the first antioxidant can be used without particular limitation, and any one of the materials listed as specific examples of the first antioxidant is used. Alternatively, two or more kinds may be mixed and used. The second antioxidant compounded in the second layer may be the same as the first antioxidant compounded in the first layer, or different from the first antioxidant compounded in the first layer. May be.

(4) The total blending amount of the second ultraviolet absorber and the second antioxidant The total blending amount of the second ultraviolet absorber and the second antioxidant is 0.5% by mass or more and 40% by mass with respect to the second elastomer component. % Or less. If the total blending amount is less than 0.5% by mass with respect to the second elastomer component, the effect expected by the addition of the second ultraviolet absorber and the second antioxidant may not be sufficiently exhibited. When this total compounding amount exceeds 40 mass% with respect to the 2nd elastomer component, the fall of the original function of a 2nd layer may be caused. Preferably, the total blending amount is 2.0% by mass or more and 20% by mass or less with respect to the second elastomer component.

  One or more of the materials listed as specific examples of the first ultraviolet absorber may be used in combination with one or more of the materials listed as specific examples of the first antioxidant. For example, it is preferable to use a combination of a benzotriazole ultraviolet absorber and a hindered phenol antioxidant.

(5) Oxygen absorbent It is preferable that an oxygen absorbent is blended in the second layer. As an oxygen absorber, the material enumerated as an oxygen absorber mix | blended with a 1st layer can be used without being specifically limited.

(6) Tackifier It is preferable that a tackifier is blended in the second layer. Thereby, the same effect as the effect acquired by mix | blending the tackifier with the 1st layer is acquired.

  When the tackifier is blended in the second layer, the tackifier is preferably blended in an amount of 1 to 100 parts by mass, and 1 to 50 parts by mass with respect to 100 parts by mass of the second elastomer component. More preferably. The effect acquired by mix | blending a tackifier cannot fully be acquired as the compounding quantity of a tackifier is less than 1 mass part with respect to 100 mass parts of 2nd elastomer components. On the other hand, when the compounding amount of the tackifier exceeds 100 parts by mass with respect to 100 parts by mass of the second elastomer component, steering stability or air permeation resistance during running tends to decrease.

For the same reason as the tackifier incorporated in the first layer, the mass average molecular weight of the tackifier by GPC measurement is preferably 1 × 10 ² to 1 × 10 ⁶ , and the softening point of the tackifier is 50 ° C. It is preferable to be in the range of ˜150 ° C. When the softening point of the tackifier is less than 50 ° C., the rubber hardness of the tire is greatly lowered, and the steering stability tends to be lowered. As the tackifier compounded in the second layer, the materials listed as specific examples of the tackifier compounded in the first layer can be used without particular limitation, and the adhesive compounded in the first layer Any one of the materials listed as specific examples of the imparting agent may be used, or two or more materials may be mixed and used. The tackifier compounded in the second layer may be the same as the tackifier compounded in the first layer, or may be different from the tackifier compounded in the first layer.

(7) Polyisobutylene It is preferable that polyisobutylene is blended in the second layer. Thereby, the same effect as that obtained by blending polyisobutylene in the first layer is obtained.

  When the second layer contains polyisobutylene, the polyisobutylene is preferably contained in an amount of 3 to 20 parts by mass and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the second elastomer component. preferable. If the content of polyisobutylene is less than 3 parts by mass with respect to 100 parts by mass of the second elastomer component, the effect obtained by blending polyisobutylene may not be sufficiently obtained. On the other hand, when the content of polyisobutylene exceeds 20 parts by mass with respect to 100 parts by mass of the second elastomer component, the fracture strength may be reduced.

  For the same reason as the polyisobutylene compounded in the first layer, the molecular weight of the polyisobutylene is preferably 9000 or more and 60000 or less, and more preferably 12000 or more and 51000 or less.

(8) Thickness of the second layer The thickness of the second layer (T2 in FIG. 2) is 0.01 to 0.3 mm. Here, the thickness T2 of the second layer means the thickness of the SIS layer when the second layer consists of only the SIS layer, and the thickness of the SIB layer when the second layer consists of only the SIB layer. When the second layer has a multilayer structure such as a two-layer structure of an SIS layer and an SIB layer, it means the total thickness of the multilayer structure. When the thickness T2 of the second layer is less than 0.01 mm, the second layer is broken by pressing pressure during vulcanization of the raw tire in which the polymer laminate is applied to the inner liner, and the vulcanization adhesive strength is reduced. There is a fear. On the other hand, if the thickness T2 of the second layer exceeds 0.3 mm, the tire mass increases and the fuel efficiency performance decreases. The thickness T2 of the second layer is preferably 0.05 to 0.2 mm.

  The second layer can be obtained according to a usual method of forming a film of a thermoplastic resin or a thermoplastic elastomer. For example, a second rubber composition containing a second elastomer component, a second ultraviolet absorber, and a second antioxidant. The product can be obtained by forming into a film by extrusion molding or calendering. The second layer may further contain other additives such as a reinforcing agent, a vulcanizing agent, a vulcanization accelerator, various oils, an anti-aging agent, a softening agent, a plasticizer, or a coupling agent.

  Examples of forms that the inner liner (polymer laminate) in the present invention can take are shown in FIGS. In the example shown in FIG. 4, the polymer laminate 10 that is an inner liner includes a SIBS layer 11 as a first layer and a SIS layer 12 as a second layer. The polymer laminate 10 is placed toward the outer side in the tire radial direction so that the SIS layer 12 is in contact with the carcass ply 61. Thereby, the adhesive strength between the SIS layer 12 and the carcass ply 61 can be increased in the tire vulcanization process. Therefore, the obtained pneumatic tire can have excellent air permeation resistance and durability because the inner liner and the rubber layer of the carcass ply 61 are well bonded.

  In the example shown in FIG. 5, the polymer laminate 10 includes an SIBS layer 11 as a first layer and an SIB layer 13 as a second layer. The polymer laminate 10 is installed toward the outer side in the tire radial direction so that the SIB layer 13 is in contact with the carcass ply 61. Thereby, the adhesive strength between the SIB layer 13 and the carcass ply 61 can be increased in the tire vulcanizing step. Therefore, the obtained pneumatic tire can have excellent air permeation resistance and durability because the inner liner and the rubber layer of the carcass ply 61 are well bonded.

<Method for producing polymer laminate>
The polymer laminate (unvulcanized) is a first rubber composition containing a first elastomer component, a first ultraviolet absorber, and a first antioxidant (the first rubber composition forms the first layer). And a second rubber composition containing a second elastomer component, a second ultraviolet absorber, and a second antioxidant (the second rubber composition forms the second layer), for example, FIG. 4 or FIG. Can be obtained by laminating extrusion such as laminating extrusion or coextrusion.

<Pneumatic tire manufacturing method>
A general manufacturing method can be used for the pneumatic tire of the present invention. That is, it can be manufactured by applying the polymer laminate 10 to an inner liner of a raw tire of the pneumatic tire 1 and vulcanizing it together with other members. When the polymer laminate 10 is arranged on the green tire, the second layer (such as the SIS layer 12 or the SIB layer 13) of the polymer laminate 10 is arranged outward in the tire radial direction so as to be in contact with the carcass ply 61. With this arrangement, the adhesive strength between the second layer and the carcass ply 61 can be increased in the tire vulcanization step. The obtained pneumatic tire can have excellent air permeation resistance and durability because the inner liner and the rubber layer of the carcass ply 61 are well bonded.

  The rubber layer of the carcass ply used in the pneumatic tire of the present invention is made of generally used rubber components such as natural rubber, polyisoprene, styrene-butadiene rubber, polybutadiene rubber, and fillers such as carbon black and silica. Can be used.

  Here, when the rubber composition constituting the first layer and / or the second layer of the polymer laminate includes the above tackifier, the rubber composition is softened in the mold at a temperature during vulcanization, for example, 150 to 180 ° C. State (intermediate state between solid and liquid). Therefore, when the mold is opened after vulcanization, the shape of the polymer laminate is deformed when the rubber composition is in a softened state. Moreover, since the reactivity is higher in the softened state than in the solid state, it may stick to and adhere to an adjacent member. Therefore, when the polymer laminate includes a tackifier, it is preferable to provide a cooling step after vulcanization. Examples of the cooling method include a method of rapidly cooling the inside of the bladder to 50 to 120 ° C. within 10 to 300 seconds after vulcanization. As the cooling medium, one or more selected from air, water vapor, water and oil can be used.

  According to the above cooling method, the inner liner can be made thinner regardless of whether the rubber composition contains a tackifier, for example, the inner liner has a thickness of about 0.05 to 0.6 mm. Can be made smaller. This is because the releasability from the bladder of the tire obtained by vulcanization is improved by the cooling step.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Manufacture of polymer laminate>
Based on the compounding amounts shown in Tables 1 and 2, rubber compositions of Examples 1 to 17 and Comparative Compounds 1 to 13 were prepared using the materials shown below. The prepared rubber composition was pelletized with a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.). T-die extruder (screw diameter: φ80mm, L / D: 50, die lip width: 500mm, cylinder temperature: 220 ° C, film gauge: 0.30mm when forming the first layer, 0.1 when forming the second layer mm)) to obtain a polymer laminate.

[SIBS]
“Shipster SIBSTAR 102T (Shore A hardness 25, styrene component content 25% by mass, mass average molecular weight by GPC measurement: 100000)” manufactured by Kaneka Corporation as a styrene-isobutylene-styrene triblock copolymer (SIBS) ” Was used.

[Production of SIBS-modified copolymer]
In a 2 liter separable flask, 75 g of a styrene-isobutylene block copolymer (styrene content 30%, number of moles of styrene unit 0.216 mol) was substituted, and the inside of the container was replaced with nitrogen. Using a syringe, 1200 mL of n-hexane dried with molecular sieves and 1800 ml of n-butyl chloride dried with molecular sieves were added.

  Next, 30 g (0.291 mol) of methacrylic acid chloride was added using a syringe. While stirring the solution, 39.4 g (0.295 mol) of aluminum trichloride was added to initiate the reaction. After 30 minutes of reaction, about 1000 milliliters of water was added to the reaction solution and stirred vigorously to complete the reaction. The reaction solution is washed several times with a large amount of water, and further slowly added dropwise to a large amount of methanol and acetone mixed solvent (l: 1) to precipitate the reaction product, and then the reaction product is heated at 60 ° C for 24 hours. By vacuum drying, a SIBS-modified copolymer (mass average molecular weight: 150,000, styrene content: 20% by mass, acid chloride: 1.0% by mass) was obtained.

[Tackifier]
As a tackifier, C9 petroleum resin Alcon P140 (manufactured by Arakawa Chemical Industries, Ltd., softening point 140 ° C., mass average molecular weight Mw: 900) was used.

[Polyisobutylene]
As polyisobutylene, “Tetrax 3T” (viscosity average molecular weight 30000, mass average molecular weight 49000) manufactured by Nippon Oil Corporation was used.

[Ultraviolet absorber]
As the first UV absorber and the second UV absorber, “ADEKA STAB LA-36 (benzotriazole UV absorber, melting point 138-141 ° C., molecular weight 315.8, maximum absorption wavelength 353 nm, 2- ( 2′-Hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole ”was used.

[Antioxidant]
As the first and second antioxidants, “IRGANOX 1010 (hindered phenol antioxidant, melting point 110 to 125 ° C., specific gravity 1.15, molecular weight 117.7, pentaerythrityl tetrakis (3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate)) ”was used.

[SIS]
As a styrene-isoprene-styrene block copolymer (SIS), D116JP (styrene component content: 15 mass%, mass average molecular weight: 150,000) manufactured by Clayton Volima Co., Ltd. was used.

[Manufacture of SIB]
Methylcyclohexane (dried with molecular sieves) 589 mL, n-butyl chloride (dried with molecular sieves) 613 ml, and cumyl chloride 0.550 g were added to a 2 L reaction vessel equipped with a stirrer. After cooling the reaction vessel to -70 ° C, 0.35 mL of α-picoline (2-methylpyridine) and 179 mL of isobutylene were added. Further, 9.4 mL of titanium tetrachloride was added to initiate polymerization, and the solution was reacted at −70 ° C. with stirring for 2.0 hours. Next, 59 mL of styrene was added to the reaction vessel, and the reaction was continued for another 60 minutes, and then a large amount of methanol was added to stop the reaction. After removing the solvent and the like from the reaction solution, the polymer was dissolved in toluene and washed twice with water. The toluene solution was added to a methanol mixture to precipitate a polymer, and the resulting polymer was dried at 60 ° C. for 24 hours to obtain a styrene-isobutylene diblock copolymer (SIB) (styrene component content: 15 mass%, mass average molecular weight: 70000).

<Manufacture of pneumatic tires>
A raw tire in which the obtained polymer laminate was applied to an inner liner was manufactured, and then a vulcanization process was performed. In the vulcanization process, pressing was performed at 170 ° C. for 20 minutes, cooling was performed at 110 ° C. for 3 minutes without taking out from the vulcanization die, and then taking out from the vulcanization die. Water was used as the cooling medium. As a result, a 195 / 65R15 size pneumatic tire having the basic structure shown in FIG. 1 was manufactured.

<Performance test>
The following performance test was performed on the pneumatic tire manufactured as described above. The results are shown in Tables 3 to 7.

(A) Weather resistance test About the inside of an inner liner, the weather resistance test was done on the following conditions using the Sunshine super long life weather meter by Suga Test Instruments Co., Ltd. Irradiation was conducted for 60 minutes under conditions of rain for 12 minutes in a bath temperature of 63 ° C., humidity of 50% and 60 ° C., and the number of cracks in the inner liner after the test was measured. The weather resistance index was calculated by substituting the measured number of cracks into the following equation. The weather resistance index is an index based on the number of cracks in Comparative Example 1, and the greater the value of the weather resistance index, the higher the weather resistance of the tire.
Weather resistance index = (number of cracks in Comparative Example 1) / (number of cracks in each Example or other Comparative Examples) × 100.

(B) Bending crack growth test The durability running test was evaluated based on whether the inner liner was cracked or peeled off. The prototype tire was assembled into a JIS standard rim 15 × 6 JJ, the tire internal pressure was set to 150 KPa, which is lower than usual, the load was 600 kg, the speed was 100 km / h, and the running distance was 20000 km. After completion of the test, the inside of the tire was observed to measure the number of cracks or the number of peels. The bending fatigue index was calculated by substituting the measured number of cracks or number of peelings into the following formula. The flex fatigue resistance index is an index based on the number of cracks in Comparative Example 1, and the larger the flex fatigue resistance index, the smaller the flex crack growth.
Bending fatigue resistance index = (number of cracks in comparative example 1) / (number of cracks in each example or other comparative example) × 100.

(C) Elastic modulus change test Viscoelasticity of inner liner using viscoelasticity spectrum meter VES (Iwamoto Seisakusho Co., Ltd.) before traveling and after traveling a specified travel distance of 20000 km under the same conditions as the flex crack growth test. Was measured, and the rate of change in elastic modulus was calculated. The elastic modulus change index was calculated using the calculated elastic modulus change rate. The elastic modulus change index is an index based on the elastic modulus change rate in Comparative Example 1. The larger the elastic modulus change index value, the lower the elastic modulus change rate (increase rate) and the better.
Change rate of elastic modulus = (elastic modulus after running) / (elastic modulus before running) × 100
Elastic modulus change index = (Change rate of elastic modulus of Comparative Example 1) / (Change rate of elastic modulus of each Example or other Comparative Examples) × 100.

(D) Calculation of static air pressure reduction rate (% / month) The tires (195 / 65R15 steel radial PC tire) of each Example and each Comparative Example manufactured by the above-described method were assembled to a JIS standard rim 15 × 6JJ, and the initial An air pressure of 300 Kpa was sealed, left at room temperature for 90 days, the rate of decrease in air pressure was calculated, and the rate of decrease in air pressure per month (30 days) (unit:% / month) was calculated. It shows that it is so favorable that the value of static air pressure fall rate is small.

(E) Brake distance measurement test The tire after the specified travel distance of 20000 km and the tire before the travel are mounted on a domestic FR sports type vehicle, and sudden braking is applied while driving at 140 km / h on the test course. It was measured. This test was performed five times for each tire, and an average value for three times excluding the maximum value and the minimum value was calculated. The braking distance index was calculated by substituting this average value into the following equation. The braking distance index is an index based on the braking distance in Comparative Example 1, and the larger the braking distance index value, the shorter the braking distance and the better the braking performance of the tire.
Braking distance index = (braking distance of comparative example 1) / (braking distance of each embodiment or other comparative example) × 100
.

(F) Comprehensive judgment The judgment criteria for the comprehensive judgment are as shown in Table 8.

<Discussion>
Comparative Example 1 is a pneumatic tire using Comparative Formulation 1 as the first layer and Comparative Formula 9 as the second layer. The tire had insufficient weather resistance index, flex fatigue resistance index, elastic modulus change index, static air pressure reduction rate, and braking distance index.

  Comparative Example 2 is a pneumatic tire using Comparative Formulation 2 as the first layer and Comparative Formulation 9 as the second layer. Although the weather resistance index of the tire was slightly improved as compared with Comparative Example 1, the flex fatigue resistance index and the static air pressure reduction rate were the same as those of Comparative Example 1. In addition, the elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 3 is a pneumatic tire using Comparative Formulation 3 as the first layer and Comparative Formula 9 as the second layer. Although the weather resistance index of the tire was slightly improved as compared with Comparative Example 1, the flex fatigue resistance index and the static air pressure reduction rate were the same as those of Comparative Example 1. In addition, the elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 4 is a pneumatic tire using Comparative Formula 4 as the first layer and Comparative Formula 9 as the second layer. The weather resistance index, flex fatigue resistance index, and static air pressure decrease rate of the tire were slightly improved as compared with Comparative Example 1, but the elastic modulus change index and braking distance index were decreased as compared with Comparative Example 1.

  Comparative Example 5 is a pneumatic tire using Comparative Formulation 5 as the first layer and Comparative Formulation 9 as the second layer. The weather resistance index, flex fatigue resistance index, and static air pressure decrease rate of the tire were slightly improved as compared with Comparative Example 1, but the elastic modulus change index and braking distance index were decreased as compared with Comparative Example 1.

  Comparative Example 6 is a pneumatic tire using Comparative Formulation 6 as the first layer and Comparative Formula 9 as the second layer. The weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the flex fatigue resistance index, elastic modulus change index, and braking distance index were lower than those of Comparative Example 1.

  Comparative Example 7 is a pneumatic tire using Comparative Formula 3 as the first layer and Comparative Formula 10 as the second layer. The weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the flex fatigue resistance index, elastic modulus change index, and braking distance index were lower than those of Comparative Example 1.

  Comparative Example 8 is a pneumatic tire using Comparative Formulation 3 as the first layer and Comparative Formulation 11 as the second layer. Although the weather resistance index of the tire was slightly improved as compared with Comparative Example 1, the flex fatigue resistance index and the static air pressure reduction rate were the same as those of Comparative Example 1. The elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 9 is a pneumatic tire using Comparative Formulation 3 as the first layer and Comparative Formulation 12 as the second layer. The weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the flex fatigue resistance index was equivalent to that of Comparative Example 1. The elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 10 is a pneumatic tire using Comparative Formulation 3 as the first layer and Comparative Formulation 13 as the second layer. The weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the flex fatigue resistance index was equivalent to that of Comparative Example 1. The elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  In Comparative Examples 1 to 10, the total amount of the ultraviolet absorber and the antioxidant is less than 0.5% by mass or exceeds 40% by mass. Therefore, it is considered that the above results were obtained.

  Comparative Example 11 is a pneumatic tire using the implementation formulation 5 as the first layer and the comparison formulation 7 as the second layer. Although the weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, the flex fatigue resistance index, the elastic modulus change index, and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 12 is a pneumatic tire that uses Example 6 as the first layer and Comparative 13 as the second layer. The weather resistance index, flex fatigue resistance index, and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the elastic modulus change index and braking distance index were lower than Comparative Example 1.

  Comparative Example 13 is a pneumatic tire using Comparative Formulation 5 as the first layer and Implementation Formula 9 as the second layer. The weather resistance index and static air pressure reduction rate of the tire were slightly improved as compared with Comparative Example 1, but the flex fatigue resistance index was equivalent to that of Comparative Example 1. The elastic modulus change index and the braking distance index were lower than those of Comparative Example 1.

  Comparative Example 14 is a pneumatic tire using Comparative Formulation 6 as the first layer and Implementation Formula 10 as the second layer. Although the weather resistance index of the tire was slightly improved as compared with Comparative Example 1, the static air pressure reduction rate was equivalent to that of Comparative Example 1. The bending fatigue index, the elastic modulus change index, and the braking distance index decreased as compared with Comparative Example 1.

  In Comparative Example 11, the total amount of the ultraviolet absorber and the antioxidant is 0.5% by mass or more and 40% by mass or less in the first layer, but less than 0.5% by mass in the second layer. . In Comparative Example 12, the total blending amount of the ultraviolet absorber and the antioxidant is 0.5% by mass or more and 40% by mass or less in the first layer, but exceeds 40% by mass in the second layer. Yes. In Comparative Example 13, the total amount of the UV absorber and the antioxidant is 0.5% by mass or more and 40% by mass or less in the second layer, but less than 0.5% by mass in the first layer. . In Comparative Example 14, the total amount of the ultraviolet absorber and the antioxidant is 0.5% by mass or more and 40% by mass or less in the second layer, but exceeds 40% by mass in the first layer. Yes. Therefore, it is considered that the above results were obtained.

  Examples 1 to 8 are pneumatic tires using Examples 1, 2, 3, 4, 5, 6, 7, and 8 as the first layer, and Example 13 as the second layer. The weather resistance index, static air pressure decrease rate, elastic modulus change index, flex fatigue resistance index, and braking distance index of the tire were improved as compared with Comparative Example 1.

  Examples 9 to 12 are pneumatic tires using Example 5 as the first layer and Examples 14, 15, 16, and 17 as the second layer, respectively. The weather resistance index, static air pressure decrease rate, elastic modulus change index, flex fatigue resistance index, and braking distance index of the tire were improved as compared with Comparative Example 1.

  Examples 14 and 15 and Comparative Examples 15 and 16 are pneumatic tires using the working composition 2 as the first layer and the working composition 13 as the second layer. The weather resistance index, static air pressure decrease rate, elastic modulus change index, and bending fatigue index of the tire were improved as compared with Comparative Example 1. However, in Examples 14 and 15, the distance L was 0 or more and (1 + D / 2) mm or less, but in Comparative Examples 15 and 16, the distance L was larger than (1 + D / 2) mm. Therefore, the braking distance index improved in Examples 14 and 15 as compared with Comparative Example 1, but decreased in Comparative Examples 15 and 16 as compared with Comparative Example 1.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 2 tread part, 3 side wall part, 4 bead part, 5 bead core, 6 carcass ply, 6a rubber layer, 7 belt layer, 8 bead apex, 9 inner liner, 10 polymer laminated body, 11 SIBS layer, 12 SIS layer, 13 SIB layer, IL1 first layer, IL2 second layer, K code, plane passing through the cross-sectional center of KC code K, L distance, S boundary surface.

Claims (5)

A pneumatic tire comprising an inner liner disposed inside a tire, and a carcass ply provided adjacent to the inner liner and having a cord embedded in a rubber layer,
The inner liner, as an elastomer component, a styrene - isobutylene - includes only first elastomer component consisting of styrene block copolymer, and has a first ultraviolet absorbent, a first layer having no first antioxidant And a second layer having a second elastomer component containing at least one of a styrene-isoprene-styrene block copolymer and a styrene-isobutylene block copolymer, a second layer having a second ultraviolet absorber and a second antioxidant. Composed of laminates,
Distribution of the first ultraviolet absorbent total amount is more than 40 mass% 2.0 mass% or more with respect to the first elastomer component,
The total amount of the second ultraviolet absorber and the second antioxidant is 0.5% by mass or more and 40% by mass or less based on the second elastomer component,
The thickness of the first layer is 0.05 mm or more and 0.6 mm or less,
The thickness of the second layer is 0.01 mm or more and 0.3 mm or less,
The second layer is disposed so as to contact the rubber layer of the carcass ply,
A pneumatic tire, wherein a distance L from a surface passing through a center of a cross section of the cord to the second layer is 0 or more and (1 + D / 2) mm or less when the diameter of the cord is D. Distribution of the first ultraviolet absorbent total amount is 20 mass% or less 2.0% by mass or more with respect to the first elastomer component,
2. The pneumatic tire according to claim 1, wherein a total blending amount of the second ultraviolet absorber and the second antioxidant is 2.0% by mass or more and 20% by mass or less with respect to the second elastomer component.   The pneumatic tire according to claim 1 or 2, wherein at least one of a styrene-isobutylene-styrene block copolymer and a SIBS-modified copolymer is blended in the second layer.   The pneumatic tire according to any one of claims 1 to 3, wherein a tackifier or polyisobutylene is blended in any of the first layer and the second layer.   The pneumatic tire according to any one of claims 1 to 4, wherein a boundary surface between the polymer laminate and the rubber layer of the carcass ply forms an uneven shape.

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