JP5632684B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pneumatic tire in which a protective layer is disposed in a bead area inside an inner liner made of a polymer laminate.

  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 in an inner liner having a function of improving the air permeation resistance by reducing (air permeation amount), weight reduction and the like have been performed.

  At present, the rubber composition for an inner liner 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. Has 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 has better air permeation resistance than butyl rubber and that can reduce the thickness of the inner liner layer.

  Conventionally, there is a technique using a thermoplastic elastomer for reducing the weight of the inner liner layer. However, when the thermoplastic elastomer is made thinner than the conventional butyl rubber inner liner, it is not possible to satisfy the functions of air barrier and light weight at the same time. Furthermore, the strength of the inner liner is reduced by making it thinner, and the inner liner layer may be broken by the heat and pressure of the bladder during the vulcanization process.

  Patent Document 1 discloses a laminate for improving the adhesion between the inner liner layer and the rubber layer. By providing an adhesive layer on both sides of the inner liner layer, the adhesive layers come into contact with each other at the overlapping portion of the inner liner layer, and are firmly bonded by heating, thereby improving air pressure retention. . However, the adhesive layer for superimposing the inner liner layer comes into contact with the bladder in a heated state in the vulcanization process, and there is a problem that it adheres to and adheres to the bladder.

  In Patent Document 2, as a countermeasure against rubbing damage with the bladder during vulcanization, a method of applying a protective layer to the inner liner or applying it in a solution is applied, but the number of man-hours increases and there is a problem in productivity and production cost. is there.

  In Patent Document 3, a mixture of nylon resin having good air permeability and butyl rubber is formed by dynamic crosslinking to produce an inner liner layer having a thickness of 100 μm. However, nylon resin is hard at room temperature and unsuitable as an inner liner for tires. In addition, the vulcanization adhesion to the rubber layer is not performed only with the mixture obtained by the dynamic crosslinking. Therefore, the adhesion layer for vulcanization is required in addition to the inner liner layer. Therefore, the inner liner member has a complicated structure and many processes. This is disadvantageous from the viewpoint of productivity.

  Prior Document 4 disperses a maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer in an ethylene-vinyl alcohol copolymer having good air barrier properties to produce a flexible gas barrier layer. . In addition, the thermoplastic polyurethane layer has an sandwich sandwich structure, and rubber paste (70/30 of butyl rubber / natural rubber is dissolved in toluene) is applied to the surface to be bonded to the tire rubber to produce an inner liner layer. However, the modified ethylene-vinyl alcohol copolymer dispersed in a flexible resin has low adhesive strength and may be peeled off from the thermoplastic polyurethane layer. Further, the flexible resin-dispersed modified ethylene-vinyl alcohol copolymer has a soft resin dispersed therein, but has poor bending fatigue properties and breaks during running of the tire. Furthermore, although rubber paste is applied to the surface to be bonded to the tire rubber, a process different from the normal inner liner process is required, resulting in poor productivity.

  Patent Document 5 relates to a pneumatic tire in which an inner liner layer is formed using nylon having a low air permeability, and adhesion with a tire inner surface or a carcass layer, which is a rubber composition, can be improved. However, in the technique of Patent Document 5, in order to form a nylon film layer, after the nylon film is RFL-treated, it is necessary to adhere a rubber paste made of a rubber composition, and there is a problem that the process becomes complicated. . Further, in the vulcanization process, generally, after inserting the bladder body into an unvulcanized tire (raw tire) accommodated in the mold, the bladder body is inflated and pressed against the inner surface of the mold from the inside of the unvulcanized tire. However, in the inner liner layer of Patent Document 5, the nylon film layer and the bladder are in contact with each other in a heated state, and there is a problem that the nylon film layer sticks and adheres to the bladder and is torn. .

JP-A-9-19987 JP 2006-248439 A Patent No. 2999188 JP 2008-24219 A JP-A-9-165469

  The present invention is a pneumatic tire equipped with an inner liner, which is excellent in basic properties of the inner liner such as air permeation resistance and bending fatigue resistance, improves weight reduction, and reduces damage to the inner liner due to bladder rubbing. With the goal.

  The present invention is a pneumatic tire provided with an inner liner on the inner side of the tire, the inner liner comprising a first layer having a thickness of 0.05 mm to 0.6 mm made of a styrene-isobutylene-styrene triblock copolymer; , A styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer, and a polymer laminate comprising a second layer having a thickness of 0.01 mm to 0.3 mm The second layer is disposed so as to contact the rubber layer of the carcass ply, is adjacent to the inner liner, and is at least vertically up and down from a position 0.2H from the bead toe with respect to the tire cross-section height H. In the pneumatic tire, a protective layer having a thickness of 0.01 mm to 1.0 mm is disposed in a range of 04H.

  The styrene-isobutylene-styrene triblock copolymer has a styrene component content of 10 to 30% by mass, and the styrene-isoprene-styrene triblock copolymer has a styrene component content of 10 to 30% by mass. It is desirable that the weight average molecular weight is 100,000 to 290,000.

  The styrene-isobutylene diblock copolymer is preferably linear, has a styrene component content of 10 to 35% by mass, and a weight average molecular weight of 40,000 to 120,000.

The protective layer is a styrene - isobutylene - is preferably at least one styrene triblock copolymer - styrene triblock copolymer Contact and styrene - isoprene.

  Furthermore, the present invention is a method for producing the pneumatic tire, comprising the step of disposing an inner liner on the inner surface of the unvulcanized tire, wherein the thickness is within the range of 0.04H at least vertically from the position 0.2H from the bead toe. A step of arranging a protective layer of 0.01 mm to 1.0 mm, and further placing an unvulcanized tire having the protective layer on a mold and vulcanizing the bladder from the inside of the unvulcanized tire while inflating the bladder. This is a method for manufacturing a pneumatic tire.

It is typical sectional drawing which shows the right half of the pneumatic tire in one embodiment of this invention. It is an enlarged view of a bead part in a sectional view of a pneumatic tire. It is typical sectional drawing of the inner liner in one embodiment of this invention. It is typical sectional drawing of the inner liner in one embodiment of this invention. It is typical sectional drawing of the inner liner in one embodiment of this invention. It is typical sectional drawing of the inner liner in one embodiment of this invention.

  The present invention is a pneumatic tire provided with an inner liner on the inner side of the tire, the inner liner comprising a first layer having a thickness of 0.05 mm to 0.6 mm made of a styrene-isobutylene-styrene triblock copolymer; , A styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer, and a polymer laminate comprising a second layer having a thickness of 0.01 mm to 0.3 mm Preferably, the second layer is disposed so as to contact the rubber layer of the carcass ply.

  Further, adjacent to the inner side of the inner liner, with respect to the tire cross-section height H, a protection of a thickness of 0.01 mm to 1.0 mm in a range of at least 0.04H from the position 0.2H away from the bead toe. Layers are arranged.

  A pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a right half of a sectional view of a pneumatic tire for passenger cars. The pneumatic tire 1 has a tread portion 2 and sidewall portions 3 and bead portions 4 so as to form a toroid shape from both ends of the tread portion. Further, a bead core 5 is embedded in the bead portion 4. Also, a carcass ply 6 provided from one bead portion 4 to the other bead portion, with both ends folded back and locked around the bead core 5, and at least two sheets on the outer side of the crown portion of the carcass ply 6 A belt layer 7 made of a ply is arranged.

  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 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. In the region surrounded by the carcass ply and the folded portion, the bead core 5 extends from the upper end to the sidewall direction. An extending bead apex 8 is arranged.

  An inner liner 9 extending from one bead portion 4 to the other bead portion 4 is disposed on the inner side in the tire radial direction of the carcass ply 6.

  An enlarged view of the bead portion in FIG. 1 showing a cross-sectional view of the pneumatic tire is shown in FIG. In FIG. 2, the inner liner 9 is disposed adjacent to the rubber layer constituting the carcass ply 6.

  In the pneumatic tire, the inner liner 9 is present at a portion including at least 0.2H from the bead toe with respect to the tire cross-section height H. The cross-sectional shape of the green tire is curved so as to protrude in the tire lumen direction at a position 0.2H from the bead toe 4T, that is, in the vicinity where the bead apex 8 is located. Therefore, when the bladder B contracts after vulcanization, the bladder B moves in the direction of the arrow in the tire lumen. Therefore, in the vicinity of the bead toe 4T to the bead apex 8 in the high temperature state after vulcanization, that is, in the vicinity of the position of 0.2H, the inner fluidized at the high temperature during vulcanization due to the movement of the bladder during contraction. The liner is rubbed to roughen the surface and the thickness becomes non-uniform.

  Therefore, a protective layer P is arranged adjacent to the inner liner 9 in the range of at least 0.04H above and below the position 0.2H from the bead toe, and the inner liner is rubbed with the bladder B during vulcanization. It is possible to prevent the surface of 9 from becoming rough and to reduce uneven thickness.

<Arrangement of protective layer>
The protective layer P is arranged in the range of at least 0.04H above and below with respect to the position 0.2H from the bead toe. The protective layer P needs to exist in the range of at least 0.04H, and can be disposed over 0.04H. The protective layer P is usually disposed within a range of 0.01H to 0.4H with respect to the tire cross-section height H. When the upper end portion of the outer side of the protective layer P in the tire radial direction is disposed at a position exceeding 0.4H from the bead toe, the tire radial direction of the protective layer P when the unvulcanized tire is deformed from a cylindrical shape to a toroidal shape. The outer upper end portion is easily peeled off as the tire expands in the radial direction. On the other hand, if the lower end of the protective layer P on the inner side in the tire radial direction is disposed at a position less than 0.01H from the bead toe, the protective layer P in the vulcanized tire is preferably slipped on the rim. Absent.

  Although the thickness of the protective layer P is adjusted in the range of 0.01 mm or more and 1.0 mm or less from a viewpoint of a protective function and weight reduction, the range of 0.03 mm or more and 0.8 mm or less is preferable. In addition, although a thing with uniform thickness can be employ | adopted for a protective layer, the shape which gradually reduces thickness in the both end directions can also be employ | adopted that the center part is the thickest.

<Material of protective layer>
As a constituent material of the protective layer, the softening point is in the range of 150 ° C to 250 ° C, preferably 180 ° C to 200 ° C. The vulcanization temperature in a general tire vulcanization process is in the range of 150 ° C. to 180 ° C., and it is desirable that the material does not soften or flow at this vulcanization temperature. From this viewpoint, the material for the protective layer is preferably a thermoplastic elastomer, a thermoplastic resin, or a mixture thereof.

<Thermoplastic elastomer>
Thermoplastic elastomers include styrene elastomers, olefin elastomers, polyester elastomers, urethane elastomers, polyamide elastomers, isobutylene and aromatic vinyl or diene monomer copolymers, acrylic rubber (ACM), ionomers, and halogen-containing rubbers. (For example, bromide of Br-IIR, Cl-IIR, isobutylene paramethylstyrene copolymer).

The protective layer is a styrene - isobutylene - is preferably at least one styrene triblock copolymer - styrene triblock copolymer Contact and styrene - isoprene.

<Thermoplastic resin>
As thermoplastic resins, polyamide resins (nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, etc.), polyester resins (polybutylene terephthalate, polyethylene terephthalate, polyethylene) Aromatic polyesters such as isophthalate, polybutylene terephthalate / tetramethylene glycol copolymer, PET / PEI copolymer, polyarylate, polybutylene naphthalate, polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer), Polynitrile resins (for example, polyacrylonitrile, polymethacrylonitrile, acrylonitrile / styrene copolymer, methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butylene) Diene copolymers, etc.), poly (meth) acrylate resins (polymethyl methacrylate, polyethyl methacrylate, ethylene ethyl acrylate copolymers, ethylene acrylic acid copolymers, ethylene methyl acrylate resins), polyvinyl resins (acetic acid) Vinyl, polyvinyl alcohol, vinyl alcohol / ethylene copolymer, polyvinylidene chloride, polyvinyl chloride, vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer), cellulose resin (cellulose acetate, cellulose acetate butyrate) ), Fluorine resins (polyvinylidene fluoride, polyvinyl fluoride, polychlorofluoroethylene, tetrafluoroethylene / ethylene copolymer), imide resins (aromatic polyimide), and the like can be used.

<Elastomer>
In the protective layer of the present invention, the elastomer can be mixed in the range of 50% by mass or less with the above-described thermoplastic elastomer or thermoplastic resin. Here, as the elastomer, diene rubber and hydrogenated products thereof, such as o, NR, IR, epoxidized natural rubber, SBR, BR, NBR, hydrogenated NBR, hydrogenated SBR, olefin rubber, such as ethylene propylene rubber ( EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), butyl rubber (IIR), chloroprene rubber, hydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, maleic acid modified chlorinated polyethylene, silicone rubber such as methyl vinyl silicone Rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber, sulfur-containing rubber, such as polysulfide rubber, fluorine rubber, such as vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-pro Ren-based rubber, fluorine-containing silicone rubbers, such as fluorine-containing phosphazene-based rubber can be used.

<Inner liner>
In the present invention, the polymer laminate used for the inner liner includes a first layer made of styrene-isobutylene-styrene triblock copolymer (SIBS) having a thickness of 0.05 mm to 0.6 mm, styrene-isoprene-styrene tri It consists of a second layer containing at least one of a block copolymer (SIS) and a styrene-isobutylene diblock copolymer (SIB), and the thickness of the second layer is 0.01 mm to 0.3 mm.

<First layer>
In the present invention, the first layer is made of a styrene-isobutylene-styrene triblock copolymer (SIBS). Due to the isobutylene block of SIBS, the polymer film made of SIBS has excellent air permeation resistance. Therefore, when a polymer film made of SIBS is used for the inner liner, a pneumatic tire having excellent air permeation resistance can be obtained.

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

  When a pneumatic tire is manufactured by applying a polymer film made of SIBS to the inner liner, air permeation resistance can be secured. Therefore, it is not necessary to use a halogenated rubber having a high specific gravity such as a halogenated butyl rubber which has been used for imparting conventional air permeation resistance, and the amount used can be reduced even when used. As a result, the weight of the tire can be reduced and the fuel consumption can be reduced.

  The molecular weight of SIBS is not particularly limited, but the weight average molecular weight by GPC measurement is preferably 50,000 to 400,000 from the viewpoints of fluidity, molding process, rubber elasticity and the like. If the weight average molecular weight is less than 50,000, the tensile strength and the tensile elongation may be lowered, and if it exceeds 400,000, the extrusion processability may be deteriorated. From the viewpoint of improving air permeation resistance and durability, SIBS has a styrene component content in SIBS of 10 to 30% by mass, preferably 14 to 23% by mass.

  The SIBS is a copolymer in which the degree of polymerization of each block is about 10,000 to 150,000 for isobutylene from the viewpoint of rubber elasticity and handling (becomes liquid when the degree of polymerization is less than 10,000), and styrene. Then, it is preferable that it is about 5,000-30,000.

  SIBS can be obtained by a living cationic polymerization method of a general vinyl compound. For example, JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible. By using isobutylene and other compounds as vinyl compounds, It is disclosed that a polyisobutylene-based block copolymer can be produced.

  Since SIBS does not have double bonds other than aromatics in the molecule, it is more stable to ultraviolet rays than a polymer having double bonds in the molecule, such as polybutadiene, and is therefore weather resistant. Is good. Furthermore, although it has no double bond in the molecule and is a saturated rubber-like polymer, the refractive index (nD) at 20 ° C. of light with a wavelength of 589 nm is the Polymer Handbook (1989: Wiley). (Polymer Handbook, Willy, 1989)) is 1.506. This is significantly higher than other saturated rubbery polymers such as ethylene-butene copolymers.

  The thickness of the first layer made of SIBS 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 a conventional technique of forming a thermoplastic resin or thermoplastic elastomer into a film, such as extrusion molding or calender molding.

<Second layer>
In the present invention, the second layer is at least one of an SIS layer made of styrene-isoprene-styrene triblock copolymer (hereinafter also referred to as SIS) and an SIB layer made of styrene-isobutylene diblock copolymer (hereinafter also referred to as SIB). Including

  Since the isoprene block of the styrene-isoprene-styrene triblock 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.

  The molecular weight of SIS is not particularly limited, but from the viewpoint of rubber elasticity and moldability, the weight average molecular weight by GPC measurement is preferably 100,000 to 290,000. 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. It is preferable that content of the styrene component in SIS is 10-30 mass% from a viewpoint of adhesiveness, 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.

  SIS can be obtained by a general vinyl compound polymerization method, for example, by 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 diblock 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.

  SIB can be obtained by a general vinyl compound polymerization method, for example, by 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 production method is disclosed in which the reaction is stopped and vacuum-dried at 60 ° C. to obtain SIB.

  The SIB layer can be obtained by forming SIB into a film by an ordinary method of forming a thermoplastic resin or thermoplastic elastomer into a film such as extrusion molding or calendering.

  The thickness of the second layer is 0.01 mm to 0.3 mm. Here, the thickness of the second layer refers to the thickness of the SIS layer when the second layer is composed only of the SIS layer, and the thickness of the SIB layer when the second layer is composed of only the SIB layer. When a layer consists of two layers of an SIS layer and an SIB layer, it means the total thickness of the SIS layer and the SIB layer. When 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 increases and the fuel efficiency performance decreases. The thickness of the second layer is further preferably 0.05 to 0.2 mm.

<Polymer laminate>
Various structures can be adopted as the structure of the polymer laminate used for the inner liner in the present invention. These forms will be described with reference to FIGS. 3 to 6 which are schematic sectional views of the inner liner.

<Form 1>
In the embodiment of the present invention, the polymer laminate 10 is composed of a SIBS layer 11 as a first layer and a SIS layer 12 as a second layer, as shown in FIG. When the polymer laminate 10 is applied to an inner liner of a pneumatic tire, the SIS layer 12 and the carcass are disposed in the tire vulcanization process when the SIS layer 12 is installed so as to be in contact with the carcass ply 61 toward the outer side in the tire radial direction. Adhesive strength with 61 can be increased. 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.

<Form 2>
In the embodiment of the present invention, the polymer laminate 10 is composed of an SIBS layer 11 as a first layer and an SIB layer 13 as a second layer, as shown in FIG. When the polymer laminate 10 is applied to an inner liner of a pneumatic tire, if the surface of the SIB layer 13 is disposed facing the outer side in the tire radial direction so as to be in contact with the carcass ply 61, the SIB layer 13 and the carcass 61 can be increased in adhesive strength. 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.

<Mode 3>
In the embodiment of the present invention, as shown in FIG. 5, the polymer laminate 10 includes a SIBS layer 11 as a first layer, a SIS layer 12 and a SIB layer 13 as a second layer, which are laminated in the above order. Is done. When the polymer laminate 10 is applied to the inner liner 61 of a pneumatic tire, if the surface of the SIB layer 13 is installed facing the outer side in the tire radial direction so as to be in contact with the carcass ply 61, in the tire vulcanization process, The adhesive strength between the layer 13 and the carcass ply 6 can be increased. 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.

<Form 4>
In the embodiment of the present invention, as shown in FIG. 6, the polymer laminate 10 includes a SIBS layer 11 as a first layer, a SIB layer 13 as a second layer, and a SIS layer 12 laminated in the order described above. Is done. When the polymer laminate 10 is applied to an inner liner of a pneumatic tire, when the surface of the SIS layer 12 is disposed so as to contact the carcass ply 61 toward the outer side in the tire radial direction, in the tire vulcanization process, the SIS layer 12 and the carcass ply 61 can be increased in adhesive strength. Therefore, the obtained pneumatic tire 1 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 10 can be obtained by subjecting SIBS and / or at least one of SIS and SIB to laminate extrusion such as laminate extrusion or coextrusion in the order described in any one of forms 1 to 4.

<Pneumatic tire manufacturing method>
The pneumatic tire of the present invention can be manufactured by the following steps.
(A) The process of arrange | positioning an inner liner on the inner surface of an unvulcanized tire.
(B) The process of arrange | positioning the protective layer with a thickness of 0.01 mm-1.0 mm in the range of 0.04H at least up and down from the position of 0.2H from a bead toe.
(C) The process of arrange | positioning the unvulcanized tire which has arrange | positioned the said protective layer to a metal mold | die, and vulcanizing, expanding a bladder from the inner side of an unvulcanized tire.

  In the present invention, the polymer laminate 10 is applied to an inner liner of a raw tire of the pneumatic tire 1 and vulcanized and molded together with other members. When the polymer laminate 10 is arranged on the green tire, the SIS layer 12 or the SIB layer 13 that is the second layer of the polymer laminate 10 is arranged outward in the tire radial direction so as to be in contact with the carcass ply 61. When arranged in this manner, the adhesive strength between the SIS layer 12 or the SIB layer 13 and the carcass 6 can be increased in the tire vulcanization step.

  The protective layer P is affixed to the inner surface of the unvulcanized tire with a film-like protective layer P adjacent to the inner liner, put into a mold, and the bladder is expanded inside the unvulcanized tire. Vulcanization is performed. The obtained pneumatic tire has excellent air permeation resistance and durability because the inner liner and the rubber layer of the carcass ply 61 are well bonded.

  The pneumatic tires of Examples and Comparative Examples were manufactured according to the specifications shown in Table 1, and the performance was evaluated. Here, SIB, SIBS and SIS used for the first layer and the second layer used for the inner liner were prepared as follows.

<SIB>
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. The 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
<SIBS>
Shibstar SIBSTAR 102T (Shore A hardness 25, styrene component content 25 mass%, weight average molecular weight: 100,000) manufactured by Kaneka Corporation was used.

<SIS>
D1161JP (styrene component content 15 mass%, weight average molecular weight: 150,000) manufactured by Kraton Polymer Co., Ltd. was used.

  The above SIBS, SIS and SIB were pelletized with a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.). Thereafter, an inner liner was prepared using a T-die extruder (screw diameter: φ80 mm, L / D: 50, die lip width: 500 mm, cylinder temperature: 220 ° C., film gauge: 0.3 mm), or an inflation co-extruder.

  A pneumatic tire is a 195 / 65R15 size tire having the basic structure shown in FIG. 1, and a raw tire is manufactured using the polymer laminate as an inner liner, and then pressed at 170 ° C. for 20 minutes in the vulcanization process. Molded and manufactured.

<Comparative Example 1>
In the inner liner of Comparative Example 1, the following blending components were mixed with a Banbury mixer and formed into a sheet with a calendar roll to obtain a polymer film having a thickness of 1.0 mm.

Chlorobutyl (Note 1) 90 parts by weight Natural rubber (Note 2) 10 parts by weight Filler (Note 3) 50 parts by weight (Note 1) “Exon Chlorobutyl 1068” manufactured by ExxonMobil Co., Ltd. (Note 2) TSR20. (Note 3) “Seast V” (N660, nitrogen adsorption specific surface area: 27 m ² / g) manufactured by Tokai Carbon Co., Ltd.

<Comparative Examples 2 and 3>
A 0.6 mm thick SIBS layer produced by the above method was used as an inner liner. Comparative Example 2 is an example having no protective layer, and Comparative Example 3 is an example having a protective layer.

<Comparative Examples 4 and 5>
Comparative Example 4 uses an SIBS layer as the first layer of the inner liner, an SIS layer as the second layer, and does not have a protective layer. Comparative Example 5 shows the SIBS layer as the first layer of the inner liner and the SIB layer as the second layer. In this example, no protective layer is used.

<Examples 1-4>
Examples 1 and 2 are examples in which an SIBS layer is used as the first layer of the inner liner, an SIS layer is used as the second layer, and a protective layer is provided. In this example, the SIBS layer is used, the SIB layer is used as the second layer, and a protective layer is provided.

  All the protective layers including those used in Comparative Example 3 have a thickness of 0.1 mm, an upper end height of 0.28H, and a lower end height of 0.10H.

  As a material for the protective layer, Shibstar SIBSTAR 102T (Shore A hardness 25, styrene component content 25 mass%, weight average molecular weight: 100,000 SIBS) manufactured by Kaneka Corporation was used.

<Performance test>
Pneumatic tires having inner liners of Examples and Comparative Examples were produced, and the following performance tests were performed.

<Peel test>
Test pieces were prepared according to JIS K 6256 “Vulcanized rubber and thermoplastic rubber—How to determine adhesion”. A sheet of material used for the inner liner and the rubber layer is bonded and vulcanized. The peel strength was measured at the bonding interface after vulcanization. The size of the test piece was 25 mm wide, and the peel test was performed at room temperature of 23 ° C. The peel strength of Comparative Example 1 is taken as 100 and is shown as a relative value. The larger the value, the better the peel strength.

<Bending fatigue test>
According to JIS K 6260 “Demach flex cracking test method for vulcanized rubber and thermoplastic rubber”, a polymer laminate or a polymer film was attached to rubber and vulcanized to prepare a predetermined test piece having a groove in the center. . An incision was made in advance at the center of the groove of the test piece, and a test was conducted to measure crack growth by repeatedly bending and deforming. The crack length was measured at an ambient temperature of 23 ° C., a strain of 30%, and a period of 5 Hz, and the number of repetitions of bending deformation required for the crack to grow by 1 mm was calculated. Using the value of Comparative Example 1 as a reference (100), the bending fatigue properties of the polymer laminates of Examples 1 to 4 and Comparative Examples 2 to 5 were indexed. It can be said that the larger the numerical value, the better the cracks are less likely to grow. For example, the index of Example 1 is obtained by the following formula.

(Bending fatigue index) = (Number of repetitions of bending deformation of Example 1) / (Number of repetitions of bending deformation of Comparative Example 1) × 100
<Static air pressure drop rate test>
The 195 / 65R15 steel radial PC tire manufactured by the above method was assembled into a JIS standard rim 15 × 6 JJ, sealed with an initial air pressure of 300 Kpa, left at room temperature for 90 days, and the rate of decrease in air pressure was calculated.

<Bladder rubbing damage>
A 195 / 65R15 size vulcanized tire was manufactured by press molding at 170 ° C. for 20 minutes. After the vulcanized tire was cooled at 100 ° C. for 3 minutes, the vulcanized tire was taken out of the mold to produce a pneumatic tire. The bladder rubbing damage was visually inspected for damage to the inner liner layer disposed inside the vulcanized tire. The judgment criteria are as follows.

A: The number of damages of the inner liner is 0 per tire.
B: The number of damages of the inner liner is 1 or more per tire.

<Performance evaluation results>
Examples 1 to 4 all had a protective layer, and no bladder rubbing damage was observed. On the other hand, in Comparative Examples 2, 4 and 5 having no protective layer, bladder rubbing damage was observed. In Comparative Example 3 having a protective layer but only the first inner liner, the rubbing rubbing damage was observed.

  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.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 2 tread part, 3 side wall part, 4 bead part, 5 bead core, 6 carcass ply, 7 belt layer, 8 bead apex, 9 inner liner, 10 polymer laminated body, 11 SIBS layer, 12 SIS layer, 13 SIB layer, P protective layer.

Claims (5)

A pneumatic tire with an inner liner on the inside of the tire,
The inner liner includes a first layer made of styrene-isobutylene-styrene triblock copolymer having a thickness of 0.05 mm to 0.6 mm, a styrene-isoprene-styrene triblock copolymer, and a styrene-isobutylene diblock copolymer. It is composed of a polymer laminate including a second layer having a thickness of 0.01 mm to 0.3 mm including at least one of the coalesced, and the second layer is disposed so as to be in contact with the rubber layer of the carcass ply. And
Adjacent to the inner liner, a protective layer having a thickness of 0.01 mm to 1.0 mm is disposed in a range of 0.04H at least vertically from the position 0.2H from the bead toe relative to the tire cross-section height H and,
The said protective layer is the said pneumatic tire which consists of at least 1 sort (s) of a styrene-isobutylene-styrene triblock copolymer and a styrene-isoprene-styrene triblock copolymer . The pneumatic tire according to claim 1, wherein the styrene-isobutylene-styrene triblock copolymer of the first layer has a styrene component content of 10 to 30% by mass. The styrene-isoprene-styrene triblock copolymer contained in the second layer has a styrene component content of 10 to 30% by mass and a weight average molecular weight of 100,000 to 290,000. the pneumatic tire according to 2. The styrene-isobutylene diblock copolymer is linear, the styrene component content is 10 to 35% by mass, and the weight average molecular weight is 40,000 to 120,000. The pneumatic tire according to item 1 . It is a manufacturing method of the pneumatic tire according to claim 1,
Placing an inner liner on the inner surface of the unvulcanized tire,
Styrene-isobutylene-styrene triblock copolymer and styrene-isoprene-styrene triblock copolymer having a thickness of 0.01 mm to 1.0 mm in a range of 0.04 H at least vertically from the position of 0.2 H from the bead tow A step of disposing a protective layer comprising at least one of the above, further comprising disposing an unvulcanized tire having the protective layer disposed on a mold and vulcanizing the bladder from the inside of the unvulcanized tire while inflating the bladder. A method for manufacturing a pneumatic tire.

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