JP2012125969A - Polymer laminate, and pneumatic tire with inner liner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer laminate, which is reduced in thickness and excellent in air permeation resistance and adhesiveness with adjacent rubber, and a pneumatic tire with an inner liner using the same.SOLUTION: The polymer laminate includes: a first layer containing SIBS and 0.1-50 pts.mass of an organized clay mineral based on 100 pts.mass of the SIBS; and a second layer including at least one of a styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer. The thickness of the first layer is 0.05-0.6 mm, and the thickness of the second layer is 0.01-0.3 mm.

Description

  The present invention relates to a polymer laminate and a pneumatic tire using it as an inner liner.

  In recent years, tires have been reduced in weight due to a strong social demand for lower fuel consumption of vehicles. Among the tire members, the inner liner is arranged inside the tire in the radial direction of the tire and has a function to improve the air permeation resistance by reducing the amount of air leakage from the inside of the pneumatic tire to the outside (air permeation amount). However, weight reduction has come to be performed.

  Currently, the use of butyl rubber containing 70-100% by weight of butyl rubber and 30-0% by weight of natural rubber as the rubber composition for the inner liner is used to improve the air permeation resistance of the tire. . Further, the rubber compound mainly composed of butyl rubber contains about 1% by mass of isoprene in addition to butylene, and this, together with sulfur, vulcanization accelerator, and zinc white, enables crosslinking between rubber molecules. 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 has been proposed a polymer that is more excellent in air permeation resistance than butyl rubber and can make the inner liner layer thinner.

  In Patent Document 1, as a pneumatic tire capable of simultaneously suppressing air pressure reduction, improving durability, and improving fuel consumption, 100 parts by mass of a rubber component made of natural rubber and / or synthetic rubber is used. , The following general formula (I),

  (In the formula, m and n are each independently 1 to 100, and x is 1 to 1000.) The ethylene-vinyl alcohol copolymer represented by at least is contained in the range of 15 to 30 parts by mass. There has been proposed a pneumatic tire obtained by using the rubber composition for an inner liner as an inner liner layer. However, in the technique of Patent Document 1, the thickness of the rubber sheet using the rubber composition is 1 mm, and there is room for improvement in terms of weight reduction of the tire.

  Patent Document 2 proposes 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 2, in order to form a nylon film layer, after the nylon film is RFL-treated, it is necessary to bond a rubber paste made of a rubber composition, which causes a problem that the process becomes complicated. . Further, in the vulcanization process, generally, a bladder body is inserted into an unvulcanized tire (raw tire) housed in a mold, and the bladder body is inflated and pressed against the inner surface of the mold from the inside of the unvulcanized tire. The tire vulcanization method that performs vulcanization is adopted. However, in the inner liner layer of Patent Document 2, the nylon film layer and the bladder are in contact with each other in a heated state, and the nylon film layer adheres and adheres to the bladder. There is also a problem of being broken.

JP 2007-291256 A JP-A-9-165469

  An object of the present invention is to provide a polymer laminate having a small thickness and excellent air permeation resistance and adhesion to an adjacent rubber, and a pneumatic tire using the polymer laminate for an inner liner.

  The polymer laminate of the present invention comprises a styrene-isobutylene-styrene triblock copolymer and 0.1 to 50 parts by mass of an organically treated clay mineral with respect to 100 parts by mass of the styrene-isobutylene-styrene triblock copolymer. And a second layer containing at least one of a styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer, and the thickness of the first layer is 0.00. The thickness is from 05 mm to 0.6 mm, and the thickness of the second layer is from 0.01 mm to 0.3 mm.

  The styrene-isobutylene-styrene triblock copolymer preferably has a weight average molecular weight of 50,000 to 400,000 and a styrene component content of 10 to 30% by mass.

  The styrene-isoprene-styrene triblock copolymer preferably has a weight average molecular weight of 100,000 to 290,000 and a styrene component content of 10 to 30% by mass.

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

  The present invention is also a pneumatic tire in which the second layer of the polymer laminate is disposed outward in the tire radial direction.

  According to the present invention, it is possible to provide a polymer laminate having a small thickness, excellent air permeation resistance and adhesion to an adjacent rubber, and a pneumatic tire using the polymer laminate for an inner liner.

It is typical sectional drawing which shows the right half of the pneumatic tire in one embodiment of this invention. It is typical sectional drawing of the polymer laminated body in one embodiment of this invention. It is typical sectional drawing of the polymer laminated body in one embodiment of this invention. It is typical sectional drawing of the polymer laminated body in one embodiment of this invention. It is typical sectional drawing of the polymer laminated body in one embodiment of this invention.

<Polymer laminate>
The polymer laminate of the present invention comprises a styrene-isobutylene-styrene triblock copolymer (hereinafter also referred to as “SIBS”), 0.1 to 50 parts by mass of an organically treated clay mineral with respect to 100 parts by mass of the SIBS. And a second layer containing at least one of a styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer, and the thickness of the first layer is 0.05 mm. The thickness of the second layer is 0.01 mm to 0.3 mm. The 1st layer and 2nd layer which comprise the polymer laminated body of this invention are demonstrated below.

<First layer>
The thickness of the 1st layer which comprises the polymer laminated body of this invention is 0.05-0.6 mm. When the thickness of the first layer is less than 0.05 mm, the vulcanization of the raw tire in which the polymer laminate is applied to the inner liner causes the first layer to be broken by press pressure, and an air leak phenomenon occurs in the obtained tire. May occur. On the other hand, when the thickness of the first layer exceeds 0.6 mm, the tire weight increases and the fuel efficiency performance decreases. The first layer preferably further has a thickness of 0.05 to 0.4 mm.

  The first layer can be obtained by forming a film by an ordinary method of forming a film of a thermoplastic resin or a thermoplastic elastomer such as SIBS and organically treated clay mineral by extrusion molding or calendar molding.

  Such a first layer is characterized by containing SIBS and an organically treated clay mineral. Here, the “organized clay mineral” means a layered clay mineral obtained by intercalating an organic compound.

(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 produced by applying a polymer film made of SIBS to an inner liner, conventional air permeation resistance such as halogenated butyl rubber is imparted to ensure air permeation resistance by including SIBS. Therefore, the amount of use can be reduced even when the high specific gravity halogenated rubber which has been used for this purpose is not used or used. As a result, the weight of the tire can be reduced, and the effect of improving fuel consumption can be obtained.

  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.

  SIBS generally contains 10 to 40% by mass of a styrene component. It is preferable that content of the styrene component in SIBS is 10-30 mass% at the point from which air permeation resistance and durability become more favorable.

  The SIBS preferably has a molar ratio of isobutylene to styrene (isobutylene / styrene) of 40/60 to 95/5 from the viewpoint of rubber elasticity of the copolymer. In SIBS, the degree of polymerization of each block is about 10,000-150,000 for isobutylene and 5,000-30,000 for styrene from the viewpoint of rubber elasticity and handling (becomes liquid when the degree of polymerization is less than 10,000). It is preferably about 000.

  SIBS can be obtained by a general vinyl compound polymerization method, for example, a living cationic polymerization method.

  For example, JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible. By using isobutylene and other compounds as vinyl compounds, It is disclosed that a polyisobutylene-based block copolymer can be produced. In addition to this, a method for producing a vinyl compound polymer by a living cationic polymerization method is disclosed in, for example, US Pat. No. 4,946,899, US Pat. No. 5,219,948, and JP-A-3-174403. It is described in the gazette.

  Since the SIBS has no double bond other than aromatic in the molecule, it is more stable to ultraviolet rays than a polymer having a double bond in the molecule, such as polybutadiene, and therefore has a weather resistance. Good properties. 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.

(Organized clay mineral)
The organically treated clay mineral is a layered clay mineral obtained by intercalating an organic compound. When the organic compound intercalates between the layers of the layered clay mineral, the layers are expanded and the dispersibility into the polymer is improved.

  The layered clay mineral is a kind of layered silicate mineral, and the crystal structure is a stack of three layers of silicate tetrahedral layer-alumina octahedral layer-silicate tetrahedral layer, and the unit layer has a thickness of about 10 mm (1 nm), It has a very thin plate shape with a spread of 0.1 to 1 μm.

A typical example of the layered clay mineral is montmorillonite. Montmorillonite becomes positive charge deficient in a part of Al is the center atom of the alumina octahedral layer in the crystal structure is replaced by Mg, although each crystal layer itself is negatively charged, the crystal layers Na ⁺・ Insufficiency of charge is neutralized by sandwiching cations such as K ⁺ , Ca ²⁺ and Mg ^2+, and a stable state is obtained. Therefore, montmorillonite exists in a state in which a number of crystal layers are overlapped.

  When water contacts the surface of the montmorillonite plate-like crystal layer, water molecules hydrate to the exchangeable cations between the layers, and the layers expand. Further, by intercalating an organic compound between layers using the cation exchange property of montmorillonite, the layers are expanded and the dispersibility in organic solvents and polymers is improved.

  Examples of layered clay minerals include montmorillonite (especially sodium montmorillonite, magnesium montmorillonite and calcium montmorillonite), bentonite, kaolinite, nonlite, beidellite, vorconskite, hectorite, saponite, sauconite, sobokite, stevensite, subfolder Mite minerals such as phyllosilicates such as smite, vermiculite and other smectite clays, illite and illite / smectite mixtures (lectretite, talosobite, ladykite and mixtures of the above clay compounds with illite) or attapulgite and sepiolite hydrotals Site-based layered compounds are exemplified. Of these, smectite clay is preferable, and montmorillonite clay is particularly preferable. Bentonite containing a smectite clay mineral may be used. These layered clay minerals are generally obtained by collecting natural minerals and performing a predetermined refining operation. These synthetic clays can be used interchangeably.

  Examples of the organic compound that can be used as an intercalant include organic compounds having a polar group that is easily ionized in the molecule. An organic compound having a polar group causes a strong interaction with the surface of a layer covered with negative ions such as oxygen ions of smectite clay minerals, and enters (intercalates) the layered clay mineral. It is thought to expand and expand.

  As the organic compound, those having an alkyl group having 6 or more carbon atoms and having a polar group ionizing at the terminal are preferable. Examples thereof include those having a hydroxyl group or a carboxyl group, aldehydes, amines, amides, or quaternary ammonium salts.

  Examples of the organic compound having a hydroxyl group include aliphatic alcohols such as octyl alcohol and nonyl alcohol, alcohols such as aromatic alcohol substituted with an alkyl group, and phenols.

  Examples of organic compounds having a carboxyl group include linear aliphatics such as stearic acid, palmitic acid, and lauric acid, linear alkenoic acids such as oleic acid, dienoic acids such as linoleelaidic acid, and polyunsaturated acids such as trienoic acid. Examples include aliphatic acids.

Examples of aldehydes include hexyl aldehyde.
As amines or amides, polar organic compounds having one or more amines or amides, such as alkylamines, aminocycloalkanes and aminocycloalkane substituents, cycloaliphatic diamines, aliphatic amines, alkylaromatic amines, alkyldiaryls Examples include amines, aliphatic amides, etc., including primary, secondary, and / or tertiary amines or amides. Of these, alkylamines, aliphatic amines, alkylaromatic amines, and alkyldiarylamines are preferable. The said organic compound can be used individually or in mixture of 2 or more types.

  Preferred amines include 1-hexylamine, 1-heptylamine, 1-octylamine, 1-nomylamine, 1-dodecylamine, 1-hexadecylamine, 1-octadecylamine, primary amines such as oleylamine, di-n Secondary amines such as dodecylamine, di-n-hexadecylamine, di-n-octadecylamine, dimethyl-n-octylamine, dimethyl-n-decylamine, dimethyl-n-tetradecylamine, dimethyl-n-hexa Tertiary amines such as decylamine, dimethyl-n-octadecylamine, dimethyloleylamine, di-n-decylmethylamine dicocoalkylmethylamine, tri-n-octylamine, tri-n-decylamine, tri-n-hexadecyl Aliphatic amines such as amines can be mentioned.

  Preferable amides include hexylamide, heptylamide, octylamide, nonylamide, lauramide, myristamide, palmitamide, steramide, palmamid, oleamide, linoleamide and the like.

  Moreover, what has a nitrile group or a lactam group, a pyridine, ester, surfactant, ethers etc. can also be used as an organic compound which has a polar group.

  Examples of the quaternary ammonium salt include dimethyl distearyl ammonium salt, trimethyl stearyl ammonium salt, dimethyl dioctadecyl ammonium, dimethyl benzyl octadecyl ammonium, and trimethyl octadecyl ammonium.

  As a method for intercalating an organic compound into the layered clay mineral, a known method can be employed. For example, in order to contact a montmorillonite clay mineral and an organic compound, the layered clay mineral is preliminarily made to contain 10% by mass to 20 times the mass of water, and then the organic compound and the montmorillonite clay mineral are contacted. There is a method for obtaining an organically treated clay mineral.

  The cation exchange amount of the organic compound in the organically treated clay mineral is preferably 50 to 200 meg / 100 g.

  The compounding amount of the organically treated clay mineral is 0.1 to 50% by mass, more preferably 0.5 to 30% by mass with respect to 100 parts by mass of the polymer mixture. When the blending amount of the organically treated clay mineral is less than 0.1% by mass, the air permeability and the tensile property at high temperature of the polymer composition are lowered. On the other hand, when the blending amount of the organically treated clay mineral exceeds 50% by mass, the hardness of the polymer composition becomes too high and the bending fatigue property is lowered.

<Second layer>
The second layer constituting the polymer laminate of the present invention comprises a SIS layer comprising a styrene-isoprene-styrene triblock copolymer (hereinafter also referred to as “SIS”) and a styrene-isobutylene diblock copolymer (hereinafter referred to as “ At least one of the SIB layers.

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

  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 SIS, the molar ratio of isoprene and styrene (isoprene / styrene) is preferably 90/10 to 70/30. In SIS, the degree of polymerization of each block 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.

(Styrene-isobutylene diblock copolymer: SIB)
Since the isobutylene block of SIB is a soft segment, the polymer film made of SIB tends to be 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.

  The SIB preferably has a molar ratio of isobutylene units to styrene units (isobutylene units / styrene units) of 90/10 to 65/35. In SIB, the degree of polymerization of each block is preferably about 300 to 3,000 for an isobutylene block and about 10 to 1,500 for a styrene block 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 to react. A production method is disclosed in which SIB is obtained by stopping and vacuum drying at 60 ° C.

  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 is the thickness of the SIS layer when the second layer is composed of only the SIS layer, the thickness of the SIB layer when the second layer is composed of only the SIB layer, When it consists of two layers of the SIS layer and the SIB layer, it means the total thickness of the SIS layer and the SIB layer. 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. is there. On the other hand, when 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.

<Other polymers or resins>
The first layer or the second layer constituting the polymer laminate of the present invention may contain other polymers or resins in addition to the above-mentioned SIBS, SIS and SIB. For example, in addition to SIBS, nylon, PET, chlorobutyl rubber, natural rubber, ethylene propylene-diene terpolymer (EPDM), styrene butadiene rubber (SBR), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile -Butadiene rubber (NBR) etc. can be mix | blended.

<Other ingredients>
For the first layer or the second layer constituting the polymer laminate of the present invention, other reinforcing agents, vulcanizing agents, vulcanization accelerators, various oils, anti-aging agents, softening agents, plasticizers, coupling agents, etc. Various compounding agents and additives blended in the general rubber composition can be blended. Moreover, the content of these compounding agents and additives can also be set to general amounts.

<Polymer laminate>
As the structure of the polymer laminate of the present invention, the following forms shown in FIGS. Below, the polymer laminated body of each of these forms is demonstrated.

(Embodiment 1)
In one 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.

  In FIG. 1, when the polymer laminate 10 is applied to the inner liner 9 of the pneumatic tire 1, if the surface on which the SIS layer 12 exists is installed facing the outer side in the tire radial direction so as to be in contact with the carcass 6, for example, In the vulcanization step, the adhesive strength between the SIS layer 12 and the carcass 6 can be increased. Therefore, the obtained pneumatic tire 1 can have excellent air permeation resistance and durability because the inner liner 9 and the rubber layer of the carcass 6 are well bonded.

(Embodiment 2)
In one embodiment of the present invention, the polymer laminate 10 includes a SIBS layer 11 as a first layer and a SIB layer 13 as a second layer, as shown in FIG.

  In FIG. 1, when the polymer laminate 10 is applied to the inner liner 9 of the pneumatic tire 1, if the surface on which the SIB layer 13 exists is set to face the outer side in the tire radial direction so as to be in contact with the carcass 6, for example, In the vulcanization step, the adhesive strength between the SIB layer 13 and the carcass 6 can be increased. Therefore, the obtained pneumatic tire 1 can have excellent air permeation resistance and durability because the inner liner 9 and the rubber layer of the carcass 6 are well bonded.

(Embodiment 3)
In one embodiment of the present invention, as shown in FIG. 4, 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. Composed.

  In FIG. 1, when the polymer laminate 10 is applied to the inner liner 9 of the pneumatic tire 1, if the surface on which the SIB layer 13 exists is set to face the outer side in the tire radial direction so as to be in contact with the carcass 6, for example, In the vulcanization step, the adhesive strength between the SIB layer 13 and the carcass 6 can be increased. Therefore, the obtained pneumatic tire 1 can have excellent air permeation resistance and durability because the inner liner 9 and the rubber layer of the carcass 6 are well bonded.

(Embodiment 4)
In one embodiment of the present invention, as shown in FIG. 5, the polymer laminate 10 includes an SIBS layer 11 as a first layer, an SIB layer 13 as a second layer, and an SIS layer 12 in the above order. Composed.

  In FIG. 1, when the polymer laminate 10 is applied to the inner liner 9 of the pneumatic tire 1, if the surface on which the SIS layer 12 exists is installed facing the outer side in the tire radial direction so as to be in contact with the carcass 6, for example, In the vulcanization step, the adhesive strength between the SIS layer 12 and the carcass 6 can be increased. Therefore, the obtained pneumatic tire 1 can have excellent air permeation resistance and durability because the inner liner 9 and the rubber layer of the carcass 6 are well bonded.

<Method for producing polymer laminate>
The polymer laminate 10 can be obtained by laminating at least one of SIBS and SIS and SIB, for example, laminate extrusion or coextrusion in the order described in any of Embodiments 1 to 4. .

<Pneumatic tire structure>
A pneumatic tire 1 according to an embodiment of the present invention will be described with reference to FIG.

  The pneumatic tire 1 can be used for passenger cars, trucks / buses, heavy machinery and the like. The pneumatic tire 1 has a tread portion 2, a sidewall portion 3, and a bead portion 4. Further, a bead core 5 is embedded in the bead portion 4. Further, a carcass 6 provided from one bead portion 4 to the other bead portion and folded back at both ends to lock the bead core 5 and a belt layer 7 composed of two plies outside the crown portion of the carcass 6 are arranged. Has been. 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 6. Belt layer 7 is arranged so that two plies made of steel cord or cord such as aramid fiber intersect each other so that the cord is normally at an angle of 5 to 30 ° with respect to the tire circumferential direction. Is done. In the carcass, organic fiber cords such as polyester, nylon, and aramid are arranged at approximately 90 ° in the tire circumferential direction. An apex 8 is arranged. An insulation may be disposed between the inner liner 9 and the carcass 6.

<Pneumatic tire manufacturing method>
In one embodiment of the present invention, the pneumatic tire 1 is obtained by applying the polymer laminate 10 produced by using the polymer laminate production method to the inner liner portion of the raw tire of the pneumatic tire 1. In addition, it can be produced by vulcanization molding. When the polymer laminate 10 is arranged on the raw 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 6. 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. Therefore, the obtained pneumatic tire 1 can have excellent air permeation resistance and durability because the inner liner 9 and the rubber layer of the carcass 6 are well bonded.

  Further, when an insulation is arranged between the inner liner 9 and the carcass 6, the tire radius so that the SIS layer 12 or the SIB layer 13 as the second layer of the polymer laminate 10 is in contact with the insulation. By arrange | positioning toward a direction outer side, the adhesive strength of the inner liner 9 and insulation can be raised.

<Examples 1-20, Comparative Examples 1-11>
(Manufacture of 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.

(Manufacture of polymer laminates)
SIBS (Shibustar SIBSTAR 102T (Shore A hardness 25, styrene component content 25 mass%) manufactured by Kaneka Co., Ltd.) according to the formulation shown in Table 1, polymer mixture components and organically treated clay mineral or inorganic clay The mineral was pelletized with a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.).

  Here, as organically treated clay mineral, BERONE34 (layered clay mineral: hectorite clay mineral, organic compound: dimethyl distearyl ammonium salt, cation exchange amount of organic compound: 100 meg / 100 g) manufactured by Pheox is used, and is inorganic. As the clay mineral, Kunipia F manufactured by Crimine Industry Co., Ltd. was used.

  SIS (D1161JP (styrene component content: 15% by mass) manufactured by Kraton Polymer Co., Ltd.) was pelletized with a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.).

  As SIB, SIB manufactured using the manufacturing method of said SIB was pelletized with the twin-screw extruder (screw diameter: (phi) 50mm, L / D: 30, cylinder temperature: 220 degreeC).

  The obtained SIBS, SIS, and SIB pellets were coextruded to obtain polymer laminates of Examples 1 to 20 having thicknesses shown in Table 1 and Comparative Examples 1 to 11 having thicknesses shown in Table 2. In addition, as for the polymer laminated body of Examples 17-20, the SIS layer and the SIB layer are laminated | stacked in the said order on the SIBS layer.

In Comparative Example 1, 90 parts by mass of chlorobutyl (Exon Chlorobutyl 1068 manufactured by ExxonMobil Co., Ltd.), 10 parts by mass of natural rubber (NR, TSR20) and filler (“Seast manufactured by Tokai Carbon Co., Ltd.”) 50 parts by mass of V ”(N660, nitrogen adsorption specific surface area: 27 m ² / g) was 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.

  In Comparative Example 4, SIBS was used as a material constituting the first layer, and in Comparative Example 5, an organically treated clay mineral and SIBS were used as materials constituting the first layer.

  The following tests were conducted using the polymer laminates of Examples 1 to 20 and Comparative Examples 2 to 10 and the polymer films of Comparative Examples 1 and 11.

<Peel test>
The obtained polymer laminate or polymer film and a carcass rubber sheet (components: natural rubber and SBR) were overlaid and heated under pressure at 170 ° C. for 12 minutes to prepare a peeling test piece. The polymer laminate was stacked so that the SIS layer or SIB layer was in contact with the rubber sheet. Using the obtained test piece, a peel test is performed in accordance with JIS K 6256 “Vulcanized rubber and thermoplastic rubber—How to determine adhesiveness”, and the adhesive force between the inner liner and the carcass (IL / carcass adhesive force) is measured. did. The size of the test piece was 25 mm wide, and the peel test was performed at room temperature of 23 ° C. Using Comparative Example 2 as a reference (100), the peel strength of each polymer laminate was displayed as an index. The larger the peel strength index, the stronger the adhesive force between the inner liner (IL) and the carcass, which is preferable.
(Peeling force index) = (Peeling force of each formulation) ÷ (Peeling force of Comparative Example 2) × 100.

<Bending fatigue test>
In accordance with JIS K 6260 “Demach bending cracking test method for vulcanized rubber and thermoplastic rubber”, a polymer laminate or polymer film is attached to rubber and vulcanized to produce a predetermined test piece with a groove in the center. did. 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. The obtained numerical values were indexed by the following formula for the bending fatigue properties of the polymer laminates of each Example and each Comparative Example with Comparative Example 2 as a reference (100). A larger value means that cracks are less likely to grow and can be said to be good.
(Bending fatigue index) = (Number of repetitions of bending deformation of each example and each comparative example) / (Number of repetitions of bending deformation of Comparative Example 2) × 100.

(Production of pneumatic tires)
A raw tire was produced by applying the polymer films of Comparative Examples 1 and 11 manufactured as described above and the polymer laminates of Examples and Comparative Examples to the inner liner portion of the tire, respectively. The polymer laminate was disposed so that the second layer was in contact with the carcass. Next, in the vulcanization process, press molding was performed at 170 ° C. for 20 minutes to produce a 195 / 65R15 size pneumatic tire. A static air drop rate test was performed on the obtained pneumatic tire.

<Static air pressure drop rate test>
A 195 / 65R15 steel radial PC tire was assembled to a JIS standard rim 15 × 6 JJ, an initial air pressure of 300 kPa was enclosed, and the air was left at room temperature for 90 days, and the rate of decrease in air pressure was calculated.

The results are shown in Tables 1 and 2.
<Evaluation results>

  In Examples 1 to 5, with respect to 100 parts by mass of SIBS, a first layer composed of an SIBS layer (thickness 0.30 to 0.59 mm) containing 0.1 to 50 parts by mass of an organically treated clay mineral, and an SIS layer ( A polymer laminate in which a second layer having a thickness of 0.01 to 0.30 mm was laminated was used. Each example was thinner than Comparative Example 2 made of a conventional rubber composition for an inner liner, but was excellent in flex fatigue and static air reduction rate while maintaining the same peeling force.

  In Examples 6 to 10, with respect to 100 parts by mass of SIBS, a first layer composed of an SIBS layer (thickness 0.30 to 0.59 mm) containing 0.1 to 50 parts by mass of an organically treated clay mineral, and an SIB layer ( A polymer laminate in which a second layer having a thickness of 0.01 to 0.30 mm was laminated was used. Each example was thinner than Comparative Example 2 made of a conventional rubber composition for an inner liner, but was excellent in flex fatigue and static air reduction rate while maintaining the same peeling force.

  In Examples 11 to 13, with respect to 100 parts by mass of SIBS, a first layer composed of an SIBS layer (thickness 0.05 to 0.50 mm) containing 25 parts by mass of an organically treated clay mineral, and an SIS layer (thickness 0. 10 mm). A polymer laminate obtained by laminating a second layer made of (01 mm) was used. In Examples 11 to 12, the peel strength was slightly inferior to that of Comparative Example 2 made of a conventional rubber composition for an inner liner, but the bending fatigue property and the static air decrease rate were excellent. In Example 13, the peel force was slightly inferior to that of Comparative Example 2, but an extremely thin polymer laminate was able to obtain the same bending fatigue property and static air decrease rate.

  Examples 14-16 are the 1st layer which consists of a SIBS layer (thickness 0.05-0.5 mm) which contains 25 mass parts of organic-modified clay minerals with respect to 100 mass parts of SIBS, and a SIB layer (thickness 0. 0). A polymer laminate obtained by laminating a second layer made of (01 mm) was used. Examples 14-15 were thinner than the comparative example 2 which consists of a conventional rubber composition for inner liners, and although peeling force was a little inferior, bending fatigue property and static air fall rate were excellent. In Example 16, the peel force was slightly inferior to that of Comparative Example 2, but it was possible to obtain the same bending fatigue property and static air decrease rate with a very thin polymer laminate.

  In Examples 17 to 20, with respect to 100 parts by mass of SIBS, a first layer composed of a SIBS layer (thickness 0.1 to 0.5 mm) containing 25 parts by mass of an organically treated clay mineral, and a SIS layer (thickness 0. 01-0.1 mm) and a polymer laminate obtained by laminating a second layer composed of an SIB layer (thickness 0.01-0.1 mm) was used. Each example was thinner than Comparative Example 2 made of a conventional rubber composition for an inner liner, but was excellent in flex fatigue and static air reduction rate while maintaining the same peeling force.

  In Comparative Examples 1 and 2, an inner liner was prepared using a conventional rubber composition for an inner liner including natural rubber and butyl rubber, and used as a reference for comparing each example and each comparative example.

  The comparative example 3 used the polymer laminated body which laminated | stacked the 1st layer which consists of a SIBS layer (thickness 0.5mm) containing an inorganic clay mineral, and the 2nd layer which consists of a SIS layer (thickness 0.1mm). . The pneumatic tire using the polymer laminate of Comparative Example 3 was particularly inferior in bending fatigue compared to Comparative Example 2.

  In Comparative Example 4, a polymer laminate including a SIBS layer (thickness 0.04 mm) and a SIS layer (thickness 0.05 mm) was used. The pneumatic tire using the polymer laminate of Comparative Example 4 was inferior to Comparative Example 2 in all of peel strength, flex fatigue, and static air reduction rate.

  Comparative Example 5 is a polymer laminate in which a first layer (thickness 0.04 mm) containing an organically treated clay mineral but not containing SIBS and a second layer made of a SIS layer (thickness 0.1 mm) are laminated. Was used. The pneumatic tire using the polymer laminate of Comparative Example 5 was inferior to Comparative Example 2 in peel strength and static air reduction rate.

  Comparative Example 6 includes a first layer composed of a SIBS layer (thickness 0.5 mm) containing SIBS but not containing an organically treated clay mineral and a second layer composed of a SIS layer (thickness 0.1 mm). The polymer laminate was used. The pneumatic tire using the polymer laminate of Comparative Example 6 was superior to Comparative Example 2 in bending fatigue and static air reduction rate, but showed inferior performance to Example 3.

  The comparative example 7 consists of the 1st layer which consists of a SIBS layer (thickness 0.5mm) which contains 0.05 mass part of organic processing clay mineral with respect to 100 mass parts of SIBS, and a SIS layer (thickness 0.1mm). A polymer laminate in which the second layer was laminated was used. The pneumatic tire using the polymer laminate of Comparative Example 7 was superior to Comparative Example 2 in bending fatigue and static air reduction rate, but exhibited inferior performance to Example 3.

  Comparative Example 8 is a first layer composed of a SIBS layer (thickness 0.5 mm) containing 70 parts by mass of an organically treated clay mineral with respect to 100 parts by mass of SIBS, and a second layer composed of a SIS layer (thickness 0.1 mm). The polymer laminated body which laminated | stacked the layer was used. The pneumatic tire using the polymer laminate of Comparative Example 8 exhibited performance inferior in flexural fatigue as compared with Comparative Example 2.

  Comparative Example 9 includes a first layer composed of a SIBS layer (thickness 0.5 mm) containing SIBS but not containing an organically treated clay mineral, and a second layer composed of a SIB layer (thickness 0.1 mm). The polymer laminate was used. The pneumatic tire using the polymer laminate of Comparative Example 9 was superior to Comparative Example 2 in bending fatigue and static air reduction rate, but exhibited performance inferior to that in Example 8.

  The comparative example 10 used the polymer laminated body which laminated | stacked the SIS layer (thickness 0.1mm) and the SIB layer (thickness 0.1mm). The pneumatic tire using the polymer laminate of Comparative Example 10 was superior to Comparative Example 2 in peeling force and bending fatigue property, but was inferior in static air reduction rate.

  In Comparative Example 11, a polymer film composed of a SIBS layer (thickness 0.06 mm) was used. The pneumatic tire using the polymer film of Comparative Example 11 was superior in Comparative Example 2 in bending fatigue and static air reduction rate, but inferior in peeling force.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

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

Claims (5)

A first layer containing a styrene-isobutylene-styrene triblock copolymer and 0.1 to 50 parts by mass of an organically treated clay mineral with respect to 100 parts by mass of the styrene-isobutylene-styrene triblock copolymer;
A second layer containing at least one of a styrene-isoprene-styrene triblock copolymer and a styrene-isobutylene diblock copolymer,
The thickness of the first layer is 0.05 mm to 0.6 mm;
A polymer laminate, wherein the second layer has a thickness of 0.01 mm to 0.3 mm.   The polymer laminate according to claim 1, wherein the styrene-isobutylene-styrene triblock copolymer has a weight average molecular weight of 50,000 to 400,000 and a styrene component content of 10 to 30% by mass. .   The polymer according to claim 1 or 2, wherein the styrene-isoprene-styrene triblock copolymer has a weight average molecular weight of 100,000 to 290,000 and a styrene component content of 10 to 30% by mass. Laminated body.   The styrene-isobutylene diblock copolymer is linear, has a weight average molecular weight of 40,000 to 120,000, and a styrene component content of 10 to 35 mass%. The polymer laminate according to any one of the above.   A pneumatic tire in which the second layer of the polymer laminate according to any one of claims 1 to 4 is disposed outward in the tire radial direction.

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