JP5469155B2 - Pneumatic tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire, and more particularly to a method for forming an inner liner, and includes a step of manufacturing a green tire by manufacturing a laminate of an unvulcanized rubber sheet such as a carcass ply and an inner liner. The present invention relates to a tire manufacturing method.

  In recent years, tires have been made lighter due to the strong social demand for low fuel consumption of vehicles, and among the tire components, they are placed inside the tires to reduce air leakage from the inside of the pneumatic tire to the outside. Even the inner liner that is required to be made is required to be lighter.

  Currently, the rubber composition for an air barrier layer improves the air permeation resistance of a tire by using a rubber compound mainly composed of butyl rubber including, for example, 70 to 100% by mass of butyl rubber and 30 to 0% by mass of natural rubber. Things have been done. In addition to butylene, the rubber compound mainly composed of butyl rubber contains about 1% by mass of isoprene, which, when combined with sulfur, vulcanization accelerator, and zinc white, enables co-crosslinking between adjacent rubber layers. I have to. The butyl rubber usually requires a thickness of about 0.6 to 1.0 mm for passenger car tires and about 1.0 to 2.0 mm for truck and bus tires. Therefore, there is a demand for a polymer that is more excellent in air permeation resistance than butyl rubber and that can reduce the thickness of the air barrier layer.

  In forming a green tire of a pneumatic tire, as shown in FIG. 7, when the inner liner P is formed on the drum 5A, the inner liner film P2 is placed on the unvulcanized inner liner rubber P1 on the conveyor in the longitudinal direction. Both end edges in the direction are aligned and pasted in advance to form a laminated body. The inner liner film P2 of the laminated body is used as the inner surface side, and is wound around the entire circumference of the band. In general, the joint PJ is formed by overlapping at one point, and thereafter, using the stitching roller, the joint PJ of the laminate is pressed to perform air bleeding.

  In such a technique, when the inner liner film P2 and the unvulcanized inner liner rubber P1 are wound on the drum, both end edges in the longitudinal direction thereof are aligned and adhered in advance. In the overlapping joining on the drum, the thickness of the joining portion PJ formed on the circumference on the drum 5A is inevitably increased. For this reason, even if a stitching roller is applied to the joint PJ, air may remain between the joints PJ, and when the residual air expands by vulcanization molding of the green tire, the joint PJ of the laminate P is peeled off. There was a fear.

  In addition, in this technique, the end portion of the laminated body P forms a joint portion at one place on the circumference of the drum 5A. Therefore, when peeling occurs at the joint portion of the molded inner tire liner, the adjacent carcass May cause damage to the ply.

  In the prior art, it has been proposed to use a thermoplastic elastomer for the inner liner in order to reduce the weight of the pneumatic tire. However, a material that is thinner than a butyl rubber inner liner and has high air permeation resistance is inferior to a butyl rubber inner liner in terms of vulcanization adhesion to insulation rubber and carcass ply rubber adjacent to the inner liner. It will be.

  In particular, if the adhesive strength at the joint portion of the inner liner is weak, the joint portion may be peeled off during running, and the tire internal pressure may be reduced, leading to tire bursts. Moreover, since the said joining part becomes a structure where another member is exposed to an inner surface, it becomes a path | route of an air leak and it becomes easy to produce a tire internal pressure fall.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2009-208444), an inner liner film and an unvulcanized rubber sheet are attached with both ends in the extending direction being shifted from each other, and this adhesive body is wound on a drum. A technique for forming an unvulcanized tire is disclosed.

  However, in order to shift both ends in the extending direction from each other, it is necessary to cut the members one by one and cut them one by one and attach them separately to each other, which may reduce productivity. In addition, depending on the bonding method, the accuracy may deteriorate, and air may accumulate between the films, resulting in damage during tire vulcanization.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-13646) proposes to improve adhesion by using petroleum resin or terpene resin as a tackifier for SIBS which is a thermoplastic elastomer. However, in addition to SIBS, a polyamide-based polymer is blended, and there is a problem that bending crack resistance is lowered.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2010-1000067) uses natural rosin, terpene, chroman indene resin, petroleum resin or alkylphenol resin as a tackifier in a blend of SIBS and a sulfur crosslinkable polymer. Thus, it has been proposed to improve the adhesion of the carcass ply rubber.

  However, in the technology of blending 10 to 300 parts by weight of a polymer capable of sulfur vulcanization with respect to 100 parts by weight of SIBS, when the sulfur crosslinkable polymer is 100 parts by weight or less, SIBS is a matrix (sea part), The sulfur-crosslinkable polymer has a domain structure (island portion), and the adhesive force at the contact interface with the carcass rubber is not improved. In addition, when the sulfur crosslinkable polymer is 100 parts by weight or more, gas barrier properties are reduced except for butyl rubber, adhesive strength is reduced with butyl rubber, and depending on the polymer to be blended, the adhesion becomes high and the thickness is 600 μm or less. There is a problem that a film cannot be produced.

JP 2009-208444 A JP 2010-13646 A JP 2010-1000067 A

  In the present invention, when a tire is formed by winding a laminate of an inner liner and an unvulcanized rubber sheet such as a carcass ply on a molding drum, the joint between the inner liner and the unvulcanized rubber sea on the periphery of the drum The thickness uniformity is improved, the remaining of the air is prevented, and the peeling of the joint portion of the inner liner and the carcass ply is effectively reduced. And it aims at providing the manufacturing method of the pneumatic tire excellent in rolling resistance, static air pressure fall rate, and uniformity.

The present invention relates to a method for producing a pneumatic tire having an inner liner on the inside of the tire.
(A) an assembling step for producing a laminate by laminating the widthwise end of the inner liner and the widthwise end of the unvulcanized rubber sheet by shifting each other by 50 mm to 500 mm in the width direction;
(B) cutting the laminate to a predetermined length corresponding to the drum width to produce a cutting sheet;
(C) The cut sheet is wound around the entire circumference of the drum such that the cut surface is in the circumferential direction of the drum and the inner liner is on the inner surface side, and the end of the inner liner and the end of the unvulcanized rubber sheet Having a joining step of joining the position of the part by shifting a certain distance,
The inner liner is composed of a composite layer of a first layer disposed inside the tire and a second layer disposed in contact with the unvulcanized rubber sheet,
At least one of the first layer and the second layer is composed of a polymer block (A) mainly composed of isobutylene and a polymer block (B) mainly composed of an aromatic vinyl compound, and at least one block Relates to a method for producing the pneumatic tire comprising an elastomer composition containing an isobutylene-modified copolymer containing β-pinene.

  In the assembling step, the width of the inner liner and the width of the unvulcanized rubber sheet are different, and they can be bonded while being shifted in the width direction so that both end portions in the width direction do not overlap each other.

  Further, the elastomer composition of the first layer contains 10 to 100% by mass of the isobutylene-modified copolymer in the whole elastomer component, and the elastomer composition of the second layer contains the isobutylene-modified copolymer as an elastomer component. It is preferable to contain 5-80 mass% of the whole.

  And it is preferable that content of (beta) -pinene in the said butylene type modified copolymer is 0.5-25 mass%.

Furthermore, the isobutylene-based modified copolymer has a weight average molecular weight of 30,000 to 400,000, a molecular weight distribution (Mw / Mn) value of 1.3 or less, and a styrene-isobutylene-styrene block copolymer or scan styrene - it is preferred that the styrene block of the isobutylene block copolymer contains β- pinene.

  In the production method of the present invention, the inner liner using the isobutylene-based modified copolymer is laminated with the unvulcanized rubber sheet shifted from each other in the width direction, and the laminate is arranged so that the inner liner is on the inner surface side. It is wound around the entire circumference of the drum. Then, by joining the end portions of the inner liner and the unvulcanized rubber sheet at positions spaced apart from each other in the circumferential direction of the drum, the thickness difference between the joint portion of the inner liner and the joint portion of the unvulcanized rubber sheet Can be relaxed. In stitching, the air at the joints can be reliably removed, and peeling of the joints due to residual air can be reduced.

  In addition, the molded inner liner and the uncured rubber sheet such as the carcass ply are formed with a joint portion separated from each other in the circumferential direction. Therefore, even if peeling occurs at the joint portion of the carcass ply. Since the peeled portion is reinforced by the inner liner, damage and breakage of the product tire are alleviated.

  And the reinforcement effect by an inner liner when the junction part of a carcass ply peels becomes high, and the reinforcement effect by a carcass ply when a junction part of an inner liner peels becomes high.

It is the schematic which shows an assembly process. It is a perspective view which shows the outline of an assembly process. It is the schematic which shows a cutting process. (A) is sectional drawing of a cutting sheet, (b) is the schematic which shows the state which winds a cutting sheet around a drum. It is the schematic which shows a cutting process. (A) is sectional drawing of a cutting sheet, (b) is the schematic which shows the state which winds a cutting sheet around a drum. It is the schematic of the shaping | molding method of the conventional inner liner. It is a schematic sectional drawing of a pneumatic tire. It is a schematic sectional drawing which shows the arrangement | positioning state of a composite layer and a carcass ply.

The present invention is a method for manufacturing a pneumatic tire provided with an inner liner on the inner side of the tire, and the manufacturing method is performed in the following green tire molding process.
(A) An assembling step in which a laminated body is manufactured by laminating the widthwise end of the inner liner and the widthwise end of the unvulcanized rubber sheet in the widthwise direction within a range of 50 mm to 500 mm.
(B) The cutting process which manufactures a cutting sheet | seat by cut | disconnecting the said laminated body to the fixed length corresponding to a drum width.
(C) The cut sheet is wound around the entire circumference of the drum such that the cut surface is in the drum circumferential direction and the inner liner is on the inner surface side, and the end of the inner liner and the end of the unvulcanized rubber sheet A joining process in which the position of the material is joined with a certain distance.

Here, the manufacturing method of the pneumatic tire of this invention is demonstrated with reference to figures.
Embodiment 1
<Assembly process>
FIG. 1 is a lateral schematic view showing the assembly process, and FIG. 2 is a perspective schematic view showing the assembly process. In FIGS. 1 and 2, the film-like inner liner 2 is covered with a release paper, and is sent from the storage roll R1 through the first drive roller R2 in the direction of the arrow, and is separated from the release paper by the release rollers R3 and R4. To be separated. And the inner liner 2 is sent to a pair of calendar roll R7.

  On the other hand, the unvulcanized rubber sheet 3 is sent to the pair of calendar rolls R7 via the second drive roller R6. Here, the inner liner 2 and the unvulcanized rubber sheet 3 are bonded together to produce the laminate 1. The laminated body 1 is wound around the winding roll R8 and temporarily stored, or is continuously sent to the subsequent cutting process. Here, the inner liner 2 and the unvulcanized rubber sheet 3 having substantially the same width are used, and the positions of these both ends are shifted from each other, and a shift distance (amount) L is formed. Has been.

  Here, the shifting distance (amount) L is adjusted in the range of 50 mm to 500 mm, preferably in the range of 100 mm to 300 mm. This is because when the shifting distance (amount) L is smaller than 50 mm, the interval between the joint portion of the unvulcanized rubber sheet and the joint portion of the inner liner is narrowed, and adhesion failure at the joint portion is likely to occur. On the other hand, if the shifting distance (amount) L exceeds 500 mm, tire formation on the drum becomes difficult.

  The inner liner is made of an elastomer composition containing an isobutylene-based modified copolymer as a main component, and the inner liner is a single layer of a polymer sheet having a thickness of 0.05 mm to 0.6 mm. The first layer is composed of a composite layer of a second layer which is disposed on the unvulcanized rubber sheet side and is made of a thermoplastic elastomer and has a thickness of 0.01 mm to 0.3 mm. The width of the inner liner is adjusted depending on the tire size.

  In the present invention, since the inner liner and the unvulcanized rubber sheet are pressure-bonded by using a roll, there is no air accumulation, and the inner liner and the unvulcanized rubber sheet can be securely adhered to each other, and are efficient and have good productivity.

<Cutting process>
FIG. 3 is a schematic perspective view showing the cutting process. The laminated body 1 is sent from a winding roll R8 to a cutting machine by a belt conveyor, or continuously sent from an assembly process. The laminate 1 is cut at a predetermined length in the longitudinal direction according to the size of the tire to produce a cut sheet 4. Note that conventional methods such as knife cutting can be employed for cutting the laminate. The cutting direction of the cutting sheet 4 corresponds to the circumferential direction of the drum, and the cutting length in the longitudinal direction corresponds to the width direction of the drum 5. The cutting length of the inner liner is appropriately adjusted depending on the tire size.

<Joint process>
FIG. 4 is a schematic view illustrating a cutting sheet joining step. Here, FIG. 4A is a cross-sectional view of the cutting sheet 4, and FIG. 4B is a schematic view showing a method of winding the cutting sheet 4 on the drum 5. The laminate is wound so that the inner liner 2 is adjacent to the surface of the drum 5. Here, the positions where the end portions 2a, 2b of the inner liner are joined together to form a joined portion, and the positions where the end portions 3a, 3b of the unvulcanized rubber sheet are joined together to form the joined portion are Is offset.

<Tire molding and vulcanization process>
As described above, in the joining step, a laminated body of an inner liner and an unvulcanized carcass ply is manufactured and formed into a drum shape and a cylindrical shape. After the joining process, both ends of the laminate located at both ends of the drum are rolled back around the bead cores, and the center part of the laminate of the inner liner and the uncured carcass ply is bulged and deformed while narrowing the interval between the bead cores. Let Along with this operation, a belt member, tread rubber or the like is attached to the central portion of the laminate, and another rubber member such as a sidewall or bead apex is also attached to form a raw tire. A product tire can be manufactured by putting the green tire formed in this way into a mold and vulcanizing by a conventional method.

Embodiment 2
In Embodiment 2, the width W2 of the inner liner 2 is formed wider than the width W1 of the unvulcanized rubber sheet 3.

<Cutting process>
FIG. 5 is a schematic view showing a cutting process. The laminated body 1 is sent from the winding roll R8 to the cutting machine by a belt conveyor, or continuously sent from the assembly process. The laminate 1 is cut to a predetermined length in the longitudinal direction according to the size of the tire to produce a cut sheet 4. Note that conventional techniques such as knife cutting can be employed for cutting the laminate. The cutting direction of the cutting sheet 4 corresponds to the circumferential direction of the drum, while the cutting length in the longitudinal direction corresponds to the width direction of the drum 5.

<Joint process>
FIG. 6A is a cross-sectional view of the cut sheet, and FIG. 6B is a schematic view showing a state in which the cut sheet is wound around the drum. Here, the inner liner 2 is wound on the drum 5 so as to be in contact with each other, and both ends 2a and 2b are overlapped to form a joint portion. An unvulcanized rubber piece 6 is used to join the both ends 3a, 3b of the unvulcanized rubber sheet 3 such as insulation onto it. In this case, two joint portions are formed, but are offset from the joint portion position with the inner liner.

<Inner liner>
The inner liner used in the first and second embodiments of the present invention is composed of a composite layer of a first layer disposed inside the tire and a second layer disposed in contact with the rubber layer of the carcass ply. Yes. Either the first layer or the second layer is composed of an elastomer composition containing an isobutylene-based modified copolymer.

<Isobutylene-modified copolymer>
In the present invention, the isobutylene-based modified copolymer is an isobutylene-based modified copolymer comprising a polymer block (A) mainly composed of isobutylene and a polymer block (B) mainly composed of an aromatic vinyl compound. And at least one block is a random copolymer containing β-pinene.

Here, the isobutylene-based modified copolymer typically contains β-pinene in a styrene block of a styrene-isobutylene-styrene block copolymer (SIBS ) or a styrene-isobutylene block copolymer (SIB). It is a copolymer.

  The polymer block (A) containing isobutylene as a main component is a polymer block composed of 80% by mass or more of units whose soft segments are derived from isobutylene. Such a polymer block can be produced using aliphatic olefins, dienes, vinyl ethers, silanes, vinyl carbazole, acenaphthylene and the like as monomer components.

On the other hand, the polymer block (B) mainly composed of an aromatic vinyl compound is a polymer block composed of 80% by mass or more of units whose hard segments are derived from an aromatic vinyl compound.

  Examples of aromatic vinyl compounds include styrene, methyl styrene, α-methyl styrene, β-methyl styrene, 2,6-dimethyl styrene, 2,4-dimethyl styrene, α-methyl-o-methyl styrene, α-methyl- m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-dimethylstyrene, β-methyl-2,4-dimethylstyrene, chlorostyrene, 2,6 -Dichlorostyrene, 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α-chloro-m-chlorostyrene, α-chloro-p-chloro Styrene, β-chloro-o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene, α -Chloro-2,4-dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4-dichlorostyrene, t-butylstyrene, methoxystyrene, chloromethylstyrene, bromomethylstyrene, etc. Is done. Styrene and α-methylstyrene are particularly preferable from the viewpoint of cost.

  The isobutylene-based modified copolymer of the present invention is a random copolymer in which at least one of the polymer blocks (A) and (B) is β-pinene. From the viewpoint of low temperature characteristics, it is preferable to copolymerize with a polymer block (B) mainly composed of an aromatic vinyl compound.

  On the other hand, from the viewpoint of adhesiveness, it is preferably copolymerized with the polymer block (A) mainly composed of isobutylene. In this case, the content of β-pinene is preferably 0.5 to 25% by mass, more preferably 2 to 25% by mass of the isobutylene-based modified copolymer. When the content of β-pinene is less than 0.5% by mass, the adhesiveness is not sufficient, and when it exceeds 25% by mass, it becomes brittle and rubber elasticity tends to decrease.

  The structure of the isobutylene-based modified copolymer of the present invention is not particularly limited, and includes a block copolymer, a triblock copolymer, a multiblock copolymer having a linear, branched, or star-like molecular chain structure. Either of these can be selected. From the viewpoint of physical property balance and molding processability, the polymer blocks (A) and (B) are diblock copolymers ((A)-(B)) and triblock copolymers ((B)-(A)- The structure of (B)) can be adopted. These may be used alone or in combination of two or more in order to obtain desired physical properties and moldability.

  The molecular weight of the isobutylene-based modified copolymer is preferably 30,000 to 300,000 in terms of weight average molecular weight by GPC measurement from the viewpoints of fluidity, molding processability, rubber elasticity, and the like. Is particularly preferred. When the weight average molecular weight is lower than 30,000, mechanical properties tend not to be sufficiently exhibited, whereas when it exceeds 300,000, fluidity and workability tend to deteriorate. Furthermore, from the viewpoint of processing stability, the molecular weight distribution value (weight average molecular weight / number average molecular weight) of the isobutylene-based modified copolymer is preferably 1.3 or less.

<Method for producing isobutylene-based modified copolymer>
A method for producing an isobutylene-based modified copolymer is disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-195969. For example, it can be produced by polymerizing the monomer component in the presence of a polymerization initiator represented by the following general formula (I).

(CR ¹ R ² X) _n R ³ (1)
Wherein X is a halogen atom, a substituent selected from an alkoxy group having 1 to 6 carbon atoms or an acyloxy group, R ¹ and R ² are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, R ¹ , R ² may be the same or different, R ³ is a monovalent or polyvalent aromatic hydrocarbon group or a monovalent or polyvalent aliphatic hydrocarbon group, and n represents a natural number of 1 to 6. .)
The compound represented by the general formula (1) serves as an initiator, generates a carbon cation in the presence of a Lewis acid or the like, and serves as a starting point for cationic polymerization. Examples of the compound of the general formula (1) include bis (1-chloro-1-methylethyl) benzene [C ₆ H ₄ (C (CH ₃ ) ₂ Cl) ₂ ], tris (1-chloro-1-methyl). Ethyl) benzene [(ClC (CH ₃ ) ₂ ) ₃ C ₆ H ₃ ] is exemplified.

When producing an isobutylene-based modified copolymer, a Lewis acid catalyst can be allowed to coexist. The Lewis acid can be used for cationic polymerization. For example, metal halides such as TiCl ₄ , TiBr ₄ , BCl ₃ , BF ₃ , BF ₃ .OEt ₂ , ZnBr ₂ , AlCl ₃ ; Et ₂ AlCl, EtAlCl _2, etc. These organometallic halides can be used. The Lewis acid can be used in an amount of 0.1 to 100 molar equivalents relative to the compound represented by the general formula (1).

  In the production of the isobutylene-based modified copolymer, an electron donor component can be allowed to coexist. Examples of the electron donor component include pyridines, amines, amides, and sulfoxides.

  Polymerization of the isobutylene-based modified copolymer can be performed in an organic solvent, and an organic solvent that does not inhibit cationic polymerization can be used. For example, halogenated hydrocarbons such as methyl chloride, dichloromethane, chloroform, ethyl chloride, dichloroethane, alkylbenzenes such as benzene, toluene, xylene, ethylbenzene, and linear aliphatic carbonization such as ethane, propane, butane, pentane, hexane, heptane, etc. Hydrogen, branched aliphatic hydrocarbons such as 2-methylpropane and 2-methylbutane, and cyclic aliphatic hydrocarbons such as cyclohexane, methylcyclohexane and ethylcyclohexane can be used.

  The amount of the organic solvent is adjusted so that the concentration of the copolymer is 5 to 40% by mass from the viewpoint of viscosity adjustment and heat dissipation of the copolymer solution to be produced. The copolymerization reaction is preferably in the range of -20 ° C to -70 ° C.

<Elastomer composition of first layer>
In the present invention, the elastomer component of the elastomer composition used for the first layer of the inner liner is composed of an isobutylene-based modified copolymer alone or a mixture with other elastomer components.

  The isobutylene-based modified copolymer is in the range of 10 to 100% by mass, preferably 30 to 100% by mass of the entire elastomer component. When the isobutylene-based modified copolymer is less than 10% by mass, the vulcanization adhesive strength with the second layer may be reduced.

  As the elastomer component, a thermoplastic elastomer, particularly a styrene thermoplastic elastomer is preferably used. Here, the styrene thermoplastic elastomer refers to a copolymer containing a styrene block as a hard segment. For example, styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene block copolymer (SIB), styrene-butadiene-styrene block copolymer (SBS), styrene-isobutylene-styrene block copolymer (SIBS). ), Styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene There is a butadiene-butylene-styrene block copolymer (SBBS).

  The styrenic thermoplastic elastomer may have an epoxy group in its molecular structure. For example, Epofriend A1020 manufactured by Daicel Chemical Industries, Ltd. (weight average molecular weight is 100,000, epoxy equivalent is 500). An epoxy-modified styrene-butadiene-styrene copolymer (epoxidized SBS) can be used. Of the styrene-based thermoplastic elastomers, a styrene-isobutylene-styrene block copolymer is preferably used.

  A rubber component can be mixed as an elastomer component of the first layer. By mixing the rubber component, it is possible to impart adhesiveness to an adjacent carcass ply in an unvulcanized state, and to improve vulcanization adhesion to the carcass ply and insulation by vulcanization.

  The rubber component preferably contains at least one selected from the group consisting of natural rubber, isoprene rubber, chloroprene rubber and butyl rubber. The compounding amount of the rubber component is preferably in the range of 5 to 20% by mass with respect to 100 parts by mass of the thermoplastic epolymer component.

  The thickness of the first layer is 0.05 to 0.6 mm. When the thickness of the first layer is less than 0.05 mm, the first layer is broken by pressing pressure during vulcanization of a green tire in which the polymer laminate is applied to the inner liner, and an air leak phenomenon occurs in the obtained tire. May occur. On the other hand, if the thickness of the first layer exceeds 0.6 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the first layer is preferably 0.05 to 0.4 mm. The first layer can be obtained by forming SIBS into a film by an ordinary method of forming a thermoplastic resin or thermoplastic elastomer into a film such as extrusion molding or calendar molding.

<Second layer elastomer composition>
In the present invention, the elastomer component of the elastomer composition used for the second layer of the inner liner is composed of a mixture of an isobutylene-based modified copolymer and another elastomer component.

  The isobutylene-based modified copolymer is in the range of 5 to 80% by mass, preferably 10 to 60% by mass, based on the entire elastomer component. If the isobutylene-based modified copolymer is less than 5% by mass, the vulcanization adhesion with the first layer may be reduced, and if it exceeds 80% by mass, the vulcanization adhesion with the carcass ply may be reduced. There is sex.

  As the elastomer component of the elastomer composition used for the second layer, a thermoplastic elastomer, particularly a styrene thermoplastic elastomer is preferably used. Examples of styrenic thermoplastic elastomers include styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene block copolymer (SIB), styrene-butadiene-styrene block copolymer (SBS), and styrene-isobutylene-styrene. Block copolymer (SIBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer There are a combination (SEEPS) and a styrene-butadiene-butylene-styrene block copolymer (SBBS).

  In particular, a thermoplastic elastomer composition containing at least one of styrene-isoprene-styrene block copolymer (SIS) and styrene-isobutylene block copolymer (SIB) is preferable.

  Of the styrenic thermoplastic elastomers used in the second layer, SIS and SIB are particularly suitable. Since the isoprene block of the styrene-isoprene-styrene copolymer (SIS) is a soft segment, the polymer film made of SIS is easily vulcanized and bonded to the rubber component. Therefore, when a polymer film made of SIS is used for the inner liner, the inner liner is excellent in adhesiveness with, for example, the rubber layer of the carcass ply, so that a pneumatic tire excellent in durability can be obtained.

  From the viewpoint of rubber elasticity and moldability, the molecular weight of the SIS is preferably 100,000 to 290,000 in terms of weight average molecular weight as measured by GPC. If the weight average molecular weight is less than 100,000, the tensile strength may be lowered, and if it exceeds 290,000, the extrusion processability is deteriorated. The content of the styrene component in the SIS is preferably 10 to 30% by mass from the viewpoints of tackiness, adhesiveness, and rubber elasticity.

  In the present invention, the polymerization degree of each block in SIS is preferably about 500 to 5,000 for isoprene and about 50 to 1,500 for styrene from the viewpoint of rubber elasticity and handling.

  The SIS can be obtained by a general vinyl compound polymerization method, for example, a living cationic polymerization method. The SIS layer can be obtained by forming the SIS into a film by a usual method of forming a thermoplastic resin or a thermoplastic elastomer into a film such as extrusion molding or calendar molding.

  Since the isobutylene block of the styrene-isobutylene block copolymer (SIB) is a soft segment, the polymer film made of SIB is easily vulcanized and bonded to the rubber component. Therefore, when a polymer film made of SIB is used as an inner liner, the inner liner is excellent in adhesiveness with an adjacent rubber forming a carcass or an insulation, for example, so that a pneumatic tire excellent in durability is obtained. be able to.

  It is preferable to use a linear SIB from the viewpoint of rubber elasticity and adhesiveness. The molecular weight of SIB is not particularly limited, but from the viewpoint of rubber elasticity and moldability, the weight average molecular weight by GPC measurement is preferably 40,000 to 120,000. If the weight average molecular weight is less than 40,000, the tensile strength may be lowered, and if it exceeds 120,000, the extrusion processability may be deteriorated.

  The content of the styrene component in the SIB is preferably 10 to 35% by mass from the viewpoints of tackiness, adhesiveness, and rubber elasticity. In the present invention, the polymerization degree of each block in SIB is preferably about 300 to 3,000 for isobutylene and about 10 to 1,500 for styrene from the viewpoint of rubber elasticity and handling.

  The SIB can be obtained by a living polymerization method of a general vinyl compound. For example, methylcyclohexane, n-butyl chloride, and cumyl chloride are added to a stirrer, cooled to -70 ° C, and reacted for 2 hours. Then, a production method is disclosed in which a large amount of methanol is added to stop the reaction and vacuum drying is performed at 60 ° C. to obtain SIB.

  The SIB layer can be formed by a usual method of forming SIB into a film of a styrenic thermoplastic elastomer such as extrusion molding or calendar molding.

  The thickness of the second layer is preferably 0.01 mm to 0.3 mm. Here, the thickness of the second layer refers to the thickness when the second layer is composed of only one layer such as a SIS layer or SIB. On the other hand, when the second layer is a two-layer or third layer including, for example, a SIS layer and an SIB layer, it means the total thickness of these. If the thickness of the second layer is less than 0.01 mm, the second layer may be broken by the press pressure during vulcanization of the raw tire in which the polymer laminate is applied to the inner liner, and the vulcanization adhesive force may be reduced. There is. On the other hand, if the thickness of the second layer exceeds 0.3 mm, the tire weight may increase and the fuel efficiency performance may deteriorate. The thickness of the second layer is further preferably 0.05 to 0.2 mm.

  The styrenic thermoplastic elastomer may have an epoxy group in its molecular structure. For example, Epofriend A1020 manufactured by Daicel Chemical Industries, Ltd. (weight average molecular weight is 100,000, epoxy equivalent is 500). An epoxy-modified styrene-butadiene-styrene copolymer (epoxidized SBS) can also be used.

<SIBS mixture>
At least one of the first layer and the second layer may be a mixture of SIS and SIBS, or a mixture of SIB and SIBS. In this case, the mixing amount of SIBS is adjusted in the range of 10 to 80% by mass, preferably 30 to 70% by mass of the elastomer component. When the SIBS is less than 10% by mass, the adhesion with the first layer is lowered, and when the SIBS exceeds 80% by mass, the adhesion with the carcass ply tends to be lowered.

<Tackifier>
In this invention, 0.1-100 mass parts of tackifiers are mix | blended with respect to 100 mass parts of elastomer components at least any one of the said 1st layer and 2nd layer. Here, the tackifier refers to a compounding agent for increasing the tackiness of the elastomer composition, and examples thereof include the following tackifiers.

  Typically, there are C9 petroleum resin and C5 petroleum resin. Here, C9 petroleum resin is obtained by thermally decomposing naphtha to obtain useful compounds such as ethylene, propylene, butadiene, etc., but the remaining C5-C9 fraction (mainly C9 fraction) from which they have been removed is mixed. It is an aromatic petroleum resin obtained by polymerization as it is. For example, as trade names, Alcon P70, P90, P100, P125, P140, M90, M100, M115, M135 (all manufactured by Arakawa Chemical Industries, Ltd., softening point 70 to 145 ° C.), and I-MABE S100, S110 , P100, P125, P140 (all manufactured by Idemitsu Petrochemical Co., Ltd., aromatic copolymer hydrogenated petroleum resin, softening point 100-140 ° C., weight average molecular weight 700-900, bromine number 2.0-6.0 g) / 100 g) and Petcoal XL (manufactured by Tosoh Corporation).

  C5 petroleum resin is obtained by thermally decomposing naphtha to obtain useful compounds such as ethylene, propylene and butadiene. The remaining C4 to C5 fractions (mainly C5 fractions) from which they have been removed are mixed. It is an aliphatic petroleum resin obtained by polymerization as it is. Product names include Highletz G100 (Mitsui Petrochemical Co., Ltd., softening point 100 ° C.), Marcarez T100AS (Maruzen Oil Co., Ltd., softening point 100 ° C.), and Escorez 1102 (Tonex Corp., softening) The point is 110 ° C.).

  Terpene resins are, for example, YS Resin PX800N, PX1000, PX1150, PX1250, PXN1150N, Clearon P85, P105, P115, P125, P135, P150, M105, M115, K100 (all manufactured by Yasuhara Chemical Co., Ltd.) The point is 75 to 160 ° C.).

  Examples of the aromatic modified terpene resin include YS resin TO85, TO105, TO115, and TO125 (all manufactured by Yashara Chemical Co., Ltd., softening point: 75 to 165 ° C.).

  The terpene phenol resins are, for example, trade names such as TAMANOL 803L, 901 (Arakawa Chemical Industries, softening point 120 ° C. to 160 ° C.), and YS polystar U115, U130, T80, T100, T115, T145, T160 (any Also from Yashara Chemical Co., Ltd., softening point 75-165 ° C).

  Coumarone resin includes, for example, coumarone resin having a softening point of 90 ° C. (manufactured by Kobe Oil Chemical Co., Ltd.). Coumaron indene oil has, for example, 15E (manufactured by Kobe Oil Chemical Co., Ltd., pour point 15 ° C.) as a trade name.

  For example, rosin ester has a trade name of ester gum AAL, A, AAV, 105, AT, H, HP, HD (all manufactured by Arakawa Chemical Industries, Ltd., softening point 68 ° C to 110 ° C), and Harrier Star TF. , S, C, DS70L, DS90, DS130 (all manufactured by Harima Kasei Co., Ltd., softening point 68 ° C to 138 ° C).

  Examples of the hydrogenated rosin ester include super esters A75, A100, A115, and A125 (all manufactured by Arakawa Chemical Industries, Ltd., softening point: 70 ° C to 130 ° C). The alkylphenol resin includes, for example, TAMANOL 510 (manufactured by Arakawa Chemical Industries, Ltd., softening point: 75 ° C to 95 ° C) as a trade name. DCPD has a trade name of Escorez 5300 (manufactured by Tonex Co., Ltd., softening point 105 ° C.).

  As for the tackifier, the fully hydrogenated petroleum resin of C9 petroleum resin has good compatibility with SIB, and can improve the adhesion without deteriorating the gas barrier property. It also has the effect of lowering the viscosity and can be advantageously used for film extrusion.

  The tackifier is blended in the range of 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic elastomer of the first layer. When the tackifier is less than 0.1 parts by mass, the vulcanization adhesive strength with the second layer is not sufficient, while when it exceeds 100 parts by mass, the tackiness becomes too high, and the workability and productivity are reduced. The gas barrier property is further lowered.

  The second layer is disposed between the first layer inside the tire and the carcass ply, and adhesion between them is required. Then, the said tackifier is mix | blended in 0.1-100 mass parts with respect to 100 mass parts of thermoplastic elastomer of a 2nd layer, Preferably, it is 1-50 mass parts. When the tackifier is less than 0.1 parts by mass, the vulcanization adhesive strength with the first layer is not sufficient. On the other hand, when it exceeds 100 parts by mass, the tackiness becomes too high, and the workability and productivity are reduced. The gas barrier property is further lowered.

<Additive of elastomer composition>
A crosslinking agent and a crosslinking aid can be added to the elastomer composition of the first layer and the second layer. As the crosslinking agent, sulfur, tetramethylthiuram disulfide, 4,4-dithiobismorpholine, organic peroxide, phenol formaldehyde resin, and halomethylphenol can be used.

  Examples of crosslinking aids include metal oxides such as sulfenamide, benzothiazole, guanidine, dithiocarbamic acid and zinc oxide, fatty acids such as stearic acid, nitrogen-containing compounds, triallyl isocyanurate, ethylene glycol dimethacrylate, and trimethylolpropane methacrylate. Can be used. The compounding quantity of a crosslinking agent and a crosslinking adjuvant is 0.3-6 mass parts with respect to 100 mass parts of elastomer components.

  The elastomer composition may further contain a filler, an anti-aging agent, a softening agent, a processing aid and the like. As the filler, carbon black, wet silica, dry silica, calcium carbonate, kaolin, talc, clay and the like can be used. Anti-aging agents include antioxidants, UV absorbers, and light stabilizers. As the softening agent, paraffinic oil, naphthenic oil, aroma oil, rapeseed oil, dioctyl phthalate and the like can be used. Further, higher fatty acids, fatty acid esters, fatty acid metal salts, fatty acid amides, paraffin waxes, fatty alcohols, fluorine / silicone resins and the like can be used as processing aids.

<Tire structure>
A pneumatic tire provided with an inner liner inside the tire according to the present invention will be described with reference to FIG. FIG. 8 is a schematic cross-sectional view of the right half of the pneumatic tire. The pneumatic tire 11 includes a tread portion 12 and sidewall portions 13 and bead portions 14 so as to form a toroid shape from both ends of the tread portion. Further, a bead core 15 is embedded in the bead portion 14. Further, a carcass ply 16 provided from one bead portion 14 to the other bead portion and wrapped around the bead core 15 at both ends, and at least two on the outer side of the crown portion of the carcass ply 16. A belt layer 17 made of a ply is arranged.

  The belt layer 17 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 to reduce peeling at both ends of the belt layer. In the carcass ply, organic fiber cords such as polyester, nylon, and aramid are arranged at approximately 90 ° in the tire circumferential direction. An extending bead apex 18 is arranged. Further, an inner liner 9 extending from one bead portion 14 to the other bead portion 14 is disposed inside the carcass ply 16 in the tire radial direction.

  Next, FIG. 9 shows the arrangement state of the inner liner with the carcass ply in the vulcanized tire. In FIG. 9, the composite layer PL is composed of a first layer PL1 and a second layer PL2. When the composite layer PL is applied to the inner liner of a pneumatic tire, if the second layer PL2 is installed facing outward in the tire radial direction so as to be in contact with the carcass ply C, in the tire vulcanization process, The adhesive strength with the carcass C can be increased. The obtained pneumatic tire has excellent air permeation resistance because the inner liner and the rubber layer of the carcass ply C are well bonded.

<Pneumatic tire manufacturing method>
The manufacturing method of the pneumatic tire of this invention can use the conventional manufacturing method. An inner liner is manufactured using the composite layer PL. The inner tire is applied to the raw tire of the pneumatic tire 11 and vulcanized and molded together with other members. When the composite layer PL is disposed on the green tire, the second layer PL2 of the composite layer PL is disposed outward in the tire radial direction so as to be in contact with the carcass ply C. When arranged in this manner, the adhesive strength between the second layer PL2 and the carcass 6 can be increased in the tire vulcanizing step. The obtained pneumatic tire has excellent air permeation resistance because the inner liner and the rubber layer of the carcass ply C are well bonded.

The method for producing a pneumatic tire of the present invention will be described below based on examples.
<Preparation of elastomer component>
The elastomer used for the first layer and the second layer of the present invention was prepared as follows.

(1) Isobutylene-based modified copolymer (1-1) Component A-1: (styrene / β-pinene) -isobutylene- (styrene / β-pinene) block copolymer (β-pinene content: 9.7 mass) %, Number average molecular weight (Mn): 103,000).

The manufacturing method of the said component A-1 is as follows.
After replacing the inside of the container of the 2 L separable flask with nitrogen, 31.0 mL of n-hexane and 294.6 mL of butyl chloride similarly dried using molecular syringes were added using a syringe, and the polymerization container was -70. After cooling in a dry ice / methanol mixing bath at 0 ° C., a Teflon (registered trademark) liquid feeding tube is placed in a pressure-resistant glass liquefied collection tube with a three-way cock containing 88.9 mL (941.6 mmol) of isobutylene monomer. And the isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. 0.148 g (0.6 mmol) of p-dicumyl chloride and 0.07 g (0.8 mmol) of α-picoline were added. Further, 0.87 mL (7.9 mmol) of titanium tetrachloride was added to initiate polymerization. After stirring at the same temperature for 1.5 hours from the start of polymerization, 1 mL of the polymerization solution was extracted from the polymerization solution as a sample. Then, 10.4 g (99.4 mmol) of styrene monomer and 6.8 g (49.7 mmol) of β-pinene that had been cooled to −70 ° C. were uniformly stirred, and then added to the polymerization vessel. 45 minutes after adding styrene and β-pinene, about 40 mL of methanol was added to terminate the reaction. After distilling off the solvent from the reaction solution, it was dissolved in toluene and washed twice with water. The toluene solution was added to a large amount of methanol to precipitate the polymer, and the resulting product was vacuum dried at 60 ° C. for 24 hours. The molecular weight of the block copolymer obtained by GPC method was measured. The number average molecular weight (Mn) is 103,000, and Mw / Mn is 1.21.

  (1-2) Component A-2: (Styrene / β-pinene) -isobutylene- (styrene / β-pinene) block copolymer (β-pinene content: 5.3% by mass, number average molecular weight: 10,7000) ).

The manufacturing method of component A-2 is as follows.
After replacing the inside of the container of the 2 L separable flask with nitrogen, 31.0 mL of n-hexane and 294.6 mL of butyl chloride similarly dried using molecular syringes were added using a syringe, and the polymerization container was -70 ° C. After cooling in a dry ice / methanol mixing bath, a Teflon (registered trademark) feeding tube was placed in a pressure-resistant glass liquefied collection tube with a three-way cock containing 88.9 mL (941.6 mmol) of isobutylene monomer. Then, isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. 0.148 g (0.6 mmol) of p-dicumyl chloride and 0.07 g (0.8 mmol) of α-picoline were added.

  Next, 0.87 mL (7.9 mmol) of titanium tetrachloride was added to initiate polymerization. After stirring at the same temperature for 1.5 hours from the start of polymerization, 1 mL of the polymerization solution was extracted from the polymerization solution as a sample. Then, 10.4 g (99.4 mmol) of styrene monomer cooled to −70 ° C. and 3.6 g (26.3 mmol) of β-pinene were uniformly stirred and then added to the polymerization vessel. About 40 mL of methanol was added 45 minutes after addition of styrene and β-pinene to terminate the reaction. After distilling off the solvent from the reaction solution, it was dissolved in toluene and washed twice with water. Further, the toluene solution was added to a large amount of methanol to precipitate a polymer, and the obtained polymer was vacuum-dried at 60 ° C. for 24 hours. The molecular weight of the block polymer obtained by GPC method was measured. The number average molecular weight (Mn) of the block copolymer is 107,000, and Mw / Mn is 1.23.

  (1-3) Component A-3: Styrene- (isobutylene / β-pinene) -styrene block copolymer (β-pinene content 5.3 mass%, number average molecular weight 10,9000).

The manufacturing method of component A-3 is as follows.
After the inside of the polymerization vessel of the 2 L separable flask was replaced with nitrogen, 31.0 mL of n-hexane and 294.6 mL of butyl chloride dried with molecular sieves were added using a syringe and the polymerization vessel was added. After cooling in a -70 ° C dry ice and methanol mixing bath, 3.6 g (26.3 mmol) of β-pinene was added.

Next, a liquid feeding tube made of Teflon (registered trademark) was connected to a pressure-resistant glass liquefied collection tube with a three-way cock containing 88.9 mL (941.6 mmol) of isobutylene monomer, and the isobutylene monomer was placed in the polymerization vessel by nitrogen pressure. Liquid was sent. Further, 0.148 g (0.6 mmol) of p-dicumyl chloride and 0.07 g (0.8 mmol) of α-picoline were added. Next, 0.87 mL (7.9 mmol) of titanium tetrachloride was further added to initiate polymerization. 45 minutes after the start of polymerization and 10.4 g (99.4 mmol) of styrene monomer cooled to −70 ° C. was added into the polymerization vessel. About 40 mL of methanol was added 45 minutes after the addition of styrene to terminate the reaction. After distilling off the solvent from the reaction solution, it was dissolved in toluene and washed twice with water. Further, the toluene solution was added to a large amount of methanol to precipitate a polymer, and the obtained polymer was vacuum-dried at 60 ° C. for 24 hours. The molecular weight of the block copolymer obtained by GPC method was measured. The number average molecular weight (Mn) of the block copolymer is 109,000, and Mw / Mn is 1.21.

(2) SIB (styrene-isobutylene block copolymer)
To a 2 L reaction vessel equipped with a stirrer, 589 mL of methylcyclohexane (dried with molecular sieves), 613 ml of n-butyl chloride (dried with molecular sieves), and 0.550 g of cumyl chloride were added. 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 reaction was allowed to proceed for 2.0 hours while stirring the solution at -70 ° C. 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. This toluene solution was added to a methanol mixture to precipitate a polymer, and the obtained polymer was dried at 60 ° C. for 24 hours to obtain a styrene-isobutylene diblock copolymer (styrene component content: 15% by mass). , Weight average molecular weight: 70,000).

(3) SIBS (styrene-isobutylene-styrene block copolymer)
“Sibstar SIBSTAR 102T (Shore A hardness 25, styrene component content 25 mass%, weight average molecular weight: 100,000)” manufactured by Kaneka Corporation was used.

(4) SIS (styrene-isoprene-styrene block copolymer)
D1161JP (styrene component content 15 mass%, weight average molecular weight: 150,000) manufactured by Kraton Polymer Co., Ltd. was used.

  (5) “Exon Chlorobutyl 1066” manufactured by ExxonMobil Co., Ltd. was used for IIR.

<Adjustment of elastomer composition of first layer and second layer>
As shown in Tables 1 and 2, additives were blended into the elastomer component to prepare elastomer compositions for the first layer and the second layer.

(Note 1) IIR: “Exon Chlorobutyl 1066” manufactured by ExxonMobil Co., Ltd.
(Note 2) Carbon black (CB): “Seast V” (N660, N ₂ SA: 27 m ² / g) manufactured by Tokai Carbon Co., Ltd.
(Note 3) Zinc oxide (ZnO): “Zinc Hana 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
(Note 4) Stearic acid: “Lunac stearate S30” manufactured by Kao Corporation.
(Note 5) Anti-aging agent: “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 6) Vulcanization accelerator: “Noxeller DM” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 7) Sulfur: “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
(Note 8) Anti-adhesive agent: C9 petroleum resin, Alcon P140 (Arakawa Chemical Industries, Ltd., softening point 140 ° C., weight average molecular weight Mw: 900).
(Note 9) Polyisobutylene: “Tetrax 3T” (manufactured by Nippon Oil Corporation) (viscosity average molecular weight 30,000, weight average molecular weight, 49,000).

<Inner liner manufacturing method>
Based on the formulation in Table 1 and Table 2, additives are added to thermoplastic elastomers such as isobutylene-modified copolymers, SIBS, SIS and SIB, Banbury mixer, kneader, twin-screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.) to obtain an elastomer composition. Thereafter, an inner liner was produced with a T-die extruder (screw diameter: φ80 mm, L / D: 50, die lip width: 500 mm, cylinder temperature: 220 ° C.). The inner liner has a thickness of 0.3 mm (first layer: 0.25 mm, second layer: 0.05 mm).

<Unvulcanized rubber sheet>
In the present invention, a carcass ply is used as the unvulcanized rubber sheet, and the composition of the topping rubber is as follows.

<Composition A of topping rubber>
Natural rubber (Note 1) 100 parts by weight Carbon black (Note 2) 50 parts by weight Zinc flower (Note 3) 3 parts by weight Anti-aging agent (Note 4) 0.2 parts by weight Sulfur (Note 5) 1 part by weight Agent (Note 6) 1 part by mass Vulcanization aid (Note 7) 1 part by mass (Note 1) TSR20
(Note 2) “Seast V” manufactured by Tokai Carbon Co., Ltd. (N660, N ₂ SA: 27 m ² / g)
(Note 3) Zinc oxide (ZnO): “Zinc Hana 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
(Note 4) “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 5) “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
(Note 6) “Noxeller DM” manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 7) Stearic acid: “Karnaku Lunac S30” manufactured by Kao Corporation
<Manufacture of pneumatic tires>
The pneumatic tire of the present invention was manufactured based on the assembly process, the cutting process, and the joining process shown in FIGS. For details, as shown in Table 1, pneumatic tires of comparative examples and examples were manufactured. Vulcanization is press-molded at 170 ° C. for 20 minutes, cooled at 100 ° C. for 3 minutes without being taken out from the vulcanizing mold, taken out from the vulcanized tire, and 195 / 65R15 size having the basic structure shown in FIG. Manufactured. Tables 3 to 6 show the blending of the inner liner and the tire molding method together with the tire evaluation results. In each of the examples, the length of the inner liner is 1300 mm based on FIG. 5, and the shift distance (amount) L is changed to 50 mm, 500 mm, and 250 mm by changing the dimensions of the carcass ply. The width W2 of the inner liner was 1300 mm, and the width W1 of the carcass ply was 800 mm.

<Examples 1-3>
In Table 3, Examples 1 to 3 use only the isobutylene-based modified copolymer (component A-1) as the elastomer component in the first layer, and the SIS and isobutylene-based modified copolymer (component A) in the second layer. -1).

<Examples 4 to 18>
In Table 4, Examples 4-18 changed the compounding content (blending 2-16) containing an isobutylene type modified copolymer as an elastomer component in the 1st layer, and changed SIS and isobutylene type modified copolymer in the 2nd layer. It is an example using the compounding (compounding 16) which mixed the union (component A-1).

<Examples 19 to 32>
In Table 5, Examples 19-29 change the blending content (blending 5-blending 15) which contains an isobutylene modified copolymer as an elastomer component in the first layer, and SIS and isobutylene modified co-polymer in the second layer. This is an example using a blend (mixture 16) in which a polymer (component A-1) is mixed.

  Example 30 uses a blend (component A-1) (mixture 1) made of an isobutylene-modified copolymer for the first layer, and SIS and an isobutylene-modified copolymer (component A-1) for the second layer. This is an example using a mixed formulation (Formulation 22).

  Example 31 uses a blend (component A-1) (mixture 1) made of an isobutylene-modified copolymer in the first layer, and SIB and an isobutylene-modified copolymer (component A-1) in the second layer. This is an example using a mixed formulation (Formulation 23).

  Example 32 uses a blend (component A-1) (mixture 1) made of an isobutylene-based modified copolymer, and SIS and an isobutylene-modified copolymer (component A-1) and IIR are further mixed in the second layer. This is an example using a blend (blend 24).

  It is recognized that the examples of the present invention are generally superior to Comparative Example 1 described later in terms of vulcanization adhesion, flex crack growth, rolling resistance index, static air pressure reduction rate and uniformity.

<Comparative Examples 1-14>
In Table 6, Comparative Examples 1, 2, 6, 7, and 10 to 13 are examples using SIBS (Comparative Formulation 1) for the first layer and SIS or SIB for the second layer.

  Comparative Examples 3 to 5 use isobutylene-based modified copolymer (component A-1) for the first layer, and use SIS and isobutylene-modified copolymer (component A-1) (compound 16) for the second layer. In this example, the shift distance (amount) is outside the scope of the present invention.

  Comparative Example 14 uses isobutylene-based modified copolymer (component A-1) (formulation 1) for the first layer, and a mixture of SIS, isobutylene-modified copolymer (component A-1) and IIR for the second layer. This is an example using (Formulation 24).

<Performance test>
The pneumatic tire manufactured as described above was evaluated for performance by the following method.

<Vulcanization adhesion>
A carcass ply is bonded to the composite layer of the first layer and the second layer and vulcanized at 170 ° C. for 20 minutes to prepare a sample for measuring vulcanization adhesion. The peel strength was measured with a tensile tester to obtain a vulcanized adhesive strength. By the following formula, the vulcanization adhesive strength of each formulation was displayed as an index based on Comparative Example 1. In addition, it shows that vulcanization adhesive force is so high that the index | exponent of vulcanization adhesive force is large.

Vulcanization adhesion index = (vulcanization adhesion of each example) / (vulcanization adhesion of Comparative Example 1) × 100
<Bending crack growth>
The durability running test was evaluated based on whether the inner liner was cracked or peeled off. The prototype tire is assembled to a JIS standard rim 15 × 6 JJ, the tire internal pressure is set to 150 KPa, which is lower than usual, the load is 600 kg, the speed is 100 km / h, the traveling distance is 20,000 km, the inside of the tire is observed, cracks, The number of peels was measured. Using Comparative Example 1 as a reference, the crack growth property of each formulation was displayed as an index. A larger index value indicates a smaller flex crack growth.

Flex crack growth index = (number of cracks in comparative example 1) / (number of cracks in each example) × 100
<Rolling resistance index>
Using a rolling resistance tester manufactured by Kobe Steel Co., Ltd., the prototype tire was assembled to a JIS standard rim 15 × 6JJ, and the temperature was set to room temperature (30 ° C.) under conditions of a load of 3.4 kN, an air pressure of 230 kPa, and a speed of 80 km / h. And rolling resistance was measured. And based on the following formula, the comparative example 1 was made into the reference | standard 100, and the rolling resistance change rate (%) of the Example was displayed by the index | exponent. It shows that rolling resistance is reduced, so that rolling resistance change rate is large.

Rolling resistance index = (Rolling resistance of Comparative Example 1) / (Rolling resistance of Example) × 100
<Static air pressure drop rate test>
The prototype tire is assembled to a JIS standard rim 15 × 6 JJ, filled with an initial air pressure of 300 kPa, and left at room temperature for 90 days to calculate the rate of decrease in air pressure. A smaller numerical value is preferable because the air pressure is less likely to decrease.

<Uniformity>
In accordance with JASO-C607: 2000 “Tire uniformity test method for automobile tires” using a tire uniformity tester, RFV was measured, and evaluation was performed using an index with Comparative Example 1 as 100. The smaller the value, the better the uniformity. The measurement conditions were an rim of 8.0 × 17, a tire rotational speed of 60 rpm, an air pressure of 200 kPa, and a longitudinal load of 4000 kPa.

  The pneumatic tire of the present invention can be used as a pneumatic tire for trucks and buses, heavy machinery, etc. in addition to a pneumatic tire for passenger cars.

  11 Pneumatic tire, 12 tread portion, 13 sidewall portion, 14 bead portion, 15 bead core, 16 carcass ply, 17 belt layer, 18 bead apex, 19 inner liner, PL composite layer, PL1 first layer, PL2 second layer .

Claims (7)

In the manufacturing method of a pneumatic tire provided with an inner liner on the inside of the tire,
(A) an assembling step for producing a laminate by laminating the widthwise end of the inner liner and the widthwise end of the unvulcanized rubber sheet by shifting each other by 50 mm to 500 mm in the width direction;
(B) cutting the laminate to a predetermined length corresponding to the drum width to produce a cutting sheet;
(C) The cut sheet is wound around the entire circumference of the drum such that the cut surface is in the circumferential direction of the drum and the inner liner is on the inner surface side, and the end of the inner liner and the end of the unvulcanized rubber sheet Having a joining step of joining the position of the part by shifting a certain distance,
The inner liner is composed of a composite layer of a first layer disposed inside the tire and a second layer disposed in contact with the unvulcanized rubber sheet,
The elastomer composition used for the first layer comprises a polymer block (A) mainly composed of isobutylene and a polymer block (B) mainly composed of an aromatic vinyl compound, and at least one block is β- The isobutylene-based modified copolymer containing pinene is included in an amount of 10 to 100% by mass of the entire elastomer component,
The elastomer composition used for the second layer is the method for producing a pneumatic tire , wherein the isobutylene-based modified copolymer contains 5 to 80% by mass of the entire elastomer component .   2. The air according to claim 1, wherein in the assembling step, the width of the inner liner and the width of the unvulcanized rubber sheet are different, and the both ends of the width direction are bonded to each other while being shifted in the width direction so as not to overlap each other. A method for manufacturing a tire. The Lee Seo butylene-modified copolymer content of the polymer in the β- pinene method of manufacturing a pneumatic tire according to claim 1 or 2 is 0.5 to 25 mass%. The said isobutylene type | system | group modified copolymer is a weight average molecular weights 30,000-400,000, and the value of molecular weight distribution (Mw / Mn) is 1.3 or less in any one of Claims 1-3 . A method of manufacturing a pneumatic tire. The air according to any one of claims 1 to 4 , wherein the isobutylene-based modified copolymer contains β-pinene in a styrene block of a styrene-isobutylene-styrene block copolymer or a styrene-isobutylene block copolymer. A method for manufacturing a tire. In the manufacturing method of a pneumatic tire provided with an inner liner on the inside of the tire,
(A) An unvulcanized rubber sheet and an inner liner having a width wider than the width of the unvulcanized rubber sheet are prepared, and both end portions in the width direction of the unvulcanized rubber sheet have a width of the inner liner. The laminated body is manufactured by laminating the width direction end of the inner liner and the width direction end of the unvulcanized rubber sheet so as to be located inside the both ends of the direction, with a difference of 50 mm to 500 mm in the width direction. An assembly process to perform,
(B) cutting the laminate to a predetermined length corresponding to the drum width to produce a cutting sheet;
(C) The cut sheet is wound around the entire circumference of the drum so that the cut surface is in the circumferential direction of the drum and the inner liner is on the inner surface side, so that both ends in the width direction of the inner liner overlap. Having a joining process of joining,
The inner liner is composed of a composite layer of a first layer disposed inside the tire and a second layer disposed in contact with the unvulcanized rubber sheet,
The elastomer composition used for the first layer comprises a polymer block (A) mainly composed of isobutylene and a polymer block (B) mainly composed of an aromatic vinyl compound, and at least one block is β- The isobutylene-based modified copolymer containing pinene is included in an amount of 10 to 100% by mass of the entire elastomer component,
The elastomer composition used for the second layer is the method for producing a pneumatic tire, wherein the isobutylene-based modified copolymer contains 5 to 80% by mass of the entire elastomer component. The manufacturing method of the pneumatic tire of Claim 6 which joins the both ends of the width direction of an unvulcanized rubber sheet using the unvulcanized rubber piece in the said joining process.

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