JP2012116164A - Method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pneumatic tire, in which a gas between a bladder and the inside surface of the tire is discharged without damaging an inner liner in the vulcanization step of the tire and the pneumatic tire exhibits superior performance about air-in, flex-crack nature adjustment, rolling resistance and operating stability.SOLUTION: The method for manufacturing a pneumatic tire utilizes the a tire vulcanization bladder having a plurality of vent lines, and manufactures the pneumatic tire provided with the inner liner on the inner surface thereof. The inner liner has an SIBS layer having a thickness of 0.05 to 0.6 mm. The SIBS layer contains 0.5 to 40 mass% of polymer obtained by polymerizing each monomer unit of 4C. The vent lines include: a first vent line which is a part corresponding to a part between a tire bead toe part and a tire buttress part; and a second vent line which is a part corresponding to a part between the tire buttress part and a tire crown part.

Description

  The present invention relates to a method for manufacturing a pneumatic tire manufactured using a tire vulcanizing bladder.

  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. . In addition to butylene, the butyl rubber contains about 1% by mass of isoprene, which, together with sulfur, vulcanization accelerator, and zinc white, enables co-crosslinking with adjacent rubber. When the butyl rubber is used for the inner liner, a normal blend 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 / bus tires.

  Therefore, in order to reduce the weight of the tire, there has been proposed a polymer that has better air permeability than butyl rubber and can reduce the thickness of the inner liner layer. Thermoplastic elastomer compositions have been studied as candidates for such polymers.

  By the way, in the conventional vulcanization process of a pneumatic tire, the metal mold | die in which the bladder which consists of an expandable elastic body was accommodated is used. In the vulcanization step, first, a release agent is applied to the inner surface of the preformed unvulcanized tire. Next, an unvulcanized tire is inserted into the heated mold, and then gas is filled into the bladder. When the bladder is filled with gas, the bladder expands while sliding on the inner surface of the unvulcanized tire. Next, the mold is tightened and the bladder internal pressure is increased. The unvulcanized tire is pressurized by a heated mold and a bladder expanded by high-pressure gas filling, and is heated by heat conduction from the mold and the bladder. The rubber causes a vulcanization reaction by pressurization and heating, and a vulcanized tire is obtained.

  The bladder pressurizes the unvulcanized tire from the inside during expansion, and discharges the gas existing between the unvulcanized tire and the bladder. If the gas is trapped between the tire inner surface and the bladder without being discharged, the gas remains on the tire inner surface and air-in occurs. Further, residual gas causes poor vulcanization and tire failure. Therefore, in order to facilitate the discharge of gas when the bladder is expanded, a large number of concave grooves are provided from the portion corresponding to the tire crown portion on the surface of the bladder toward the portion corresponding to the tire bead portion. This groove is called a bladder vent line.

  Here, in the case where an unvulcanized tire using a thermoplastic resin composition is preformed to reduce the thickness of the inner liner layer and the tire is manufactured by the above conventional vulcanization process, after the vulcanization is completed, from the tire When shrinking and storing the bladder, there is a problem that the groove of the bladder vent line and the inner surface of the tire are rubbed and the thermoplastic resin composition constituting the inner liner layer is damaged. In particular, when the inner liner layer is made of a thermoplastic resin composition having a melting point lower than the vulcanization temperature and the thickness is less than 1 mm, the thermoplastic resin composition is softened at the end of vulcanization, so The damage of the liner layer is increased. For example, not only the inner pressure holding ability of the tire is reduced due to scratches on the inner liner layer, but there is also a risk that a crack may occur in the inner liner layer, leading to a serious accident in which the tire bursts during traveling.

  In Patent Document 1 (Japanese Patent Laid-Open No. 2008-12751), in order to efficiently discharge the gas between the bladder and the inner surface of the tire, the groove width, height, groove area of the bladder vent line, and the contour of the bladder corner are described. The ratio of the approximate radius R1 to the bladder outer diameter RA (R1 / RA), a cross vent line, and the like are disclosed.

  However, if a bladder having the bladder vent line is used for manufacturing an unvulcanized tire having an inner liner layer made of a thin thermoplastic resin composition, the inner liner layer may be damaged when the bladder contracts. .

JP 2008-12751 A

  The present invention provides a tire vulcanizing bladder capable of discharging gas between a bladder and a tire inner surface without damaging an inner liner in a tire vulcanizing process, and the tire vulcanizing bladder. An object of the present invention is to provide a method for producing a pneumatic tire that exhibits excellent performance in air-in, flex cracking adjustment, rolling resistance, and steering stability by using an inner liner with a high adhesive strength.

The method for producing a pneumatic tire according to the present invention includes an inner liner on an inner surface using a tire vulcanization bladder having a plurality of vent lines, and the inner liner is a styrene-isobutylene-styrene triblock co-polymer. It has a SIBS layer containing a polymer, the thickness of the SIBS layer is 0.05 mm or more and 0.6 mm or less, and the SIBS layer is a polymer obtained by polymerizing a monomer unit having 4 carbon atoms in an amount of 0.00. The vent line includes a first vent line corresponding to the tire buttress portion from the tire bead toe portion and a second vent corresponding to the tire crown portion from the tire buttress portion. The shape of the groove cross section of the first vent line and the second vent line is on the side in contact with the mold of the tire vulcanization bladder. The first vent line and the second vent have a width of 0.5 mm or more and 3.0 mm or less on the surface and a depth from the surface on the side in contact with the mold of the tire vulcanization bladder of 0.1 mm or more and 2.0 mm or less. groove cross-sectional area of the line is a 0.025 mm ² or more 6.0 mm ² or less, the first vent line, the angle α is 60 ° or more relative to a tangent of the portion corresponding to the tire bead toe portion 90 ° or less, and, second The vent line is characterized in that an angle β with respect to a tangent of a portion corresponding to the tire bead toe portion is not less than 40 ° and not more than 90 °, and the magnitude of the angle α and the angle β satisfies a relationship of α ≧ β.

The method for producing a pneumatic tire according to the present invention includes an inner liner on an inner surface using a tire vulcanization bladder having a plurality of vent lines, and the inner liner is a styrene-isobutylene-styrene triblock co-polymer. It has at least one of a SIBS layer containing a polymer, a SIS layer containing a styrene-isoprene-styrene triblock copolymer, and a SIB layer containing a styrene-isobutylene diblock copolymer, and the thickness of the SIBS layer is: 0.05 mm or more and 0.6 mm or less, and the total thickness of the SIS layer and the SIB layer is 0.01 mm or more and 0.3 mm or less, and at least one of the SIBS layer, the SIS layer, and the SIB layer has 4 carbon atoms. Containing 0.5% by mass to 40% by mass of a polymer obtained by polymerizing the monomer units of The line includes a first vent line corresponding to the tire buttress portion from the tire bead toe portion and a second vent line corresponding to the tire crown portion from the tire buttress portion, and the first vent line and the second vent line. The groove cross-sectional shape of the line is such that the width on the surface in contact with the mold of the bladder is 0.5 mm or more and 3.0 mm or less, and the depth from the surface on the side in contact with the mold of the bladder is 0.1 mm or more and 2.0 mm. or less, groove cross-sectional area of the first vent line and second vent line is at 0.025 mm ² or more 6.0 mm ² or less, the first vent line, an angle α with respect to the tangent of the portion corresponding to the tire bead toe portion Is 60 ° or more and 90 ° or less, and the second vent line has an angle β with respect to a tangent of a portion corresponding to the tire bead toe portion of 40 ° or more and 90 ° or less. , The magnitude of the angle alpha and angle beta is characterized by satisfying the relationship of alpha ≧ beta.

  The shape of the groove cross section of the first vent line and the second vent line is preferably a substantially rectangular shape, a substantially semicircular shape, or a substantially triangular shape.

  The polymer obtained by polymerizing the monomer unit having 4 carbon atoms is preferably composed of at least one of polybutene and polyisobutylene, more preferably a number average molecular weight of 300 to 3,000, and a weight average molecular weight of 700 to 100. Or less and a viscosity average molecular weight of 20,000 or more and 70,000 or less. The SIBS layer is preferably disposed on the innermost side in the radial direction of the pneumatic tire.

  An SIS layer containing a polymer obtained by polymerizing a monomer unit having 4 carbon atoms or an SIB layer containing a polymer obtained by polymerizing a monomer unit having 4 carbon atoms is disposed in contact with the carcass layer of the pneumatic tire. It is preferable.

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

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

  The inner liner further comprises a 2a layer comprising a 2a thermoplastic elastomer composition comprising a styrene-isoprene-styrene triblock copolymer, and a 2b thermoplastic elastomer composition comprising a styrene-isobutylene diblock copolymer. It is preferable to include a second layer including at least one of the second b layers.

  According to the present invention, in the tire vulcanization process, gas is discharged between the bladder and the tire inner surface without damaging the inner liner, and air-in, flex cracking adjustment, rolling resistance, and steering stability are performed. It is possible to provide a method for manufacturing a pneumatic tire that exhibits excellent performance in terms of performance.

It is typical sectional drawing of the right half of the pneumatic tire in one embodiment of the present invention. It is a figure which shows the bladder for tire vulcanization | cure in one embodiment of this invention. It is typical sectional drawing of the vent line in one embodiment of this invention. It is a figure which shows the vent line in one embodiment of this invention. It is typical sectional drawing of the vent line in one embodiment of this invention. It is a figure which shows the vent line in one embodiment of this invention. It is typical sectional drawing of the polymer sheet 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.

<Pneumatic tire>
The structure of the pneumatic tire manufactured by the manufacturing method of this invention is demonstrated using FIG. The pneumatic tire 101 of the present invention can be used for passenger cars, trucks / buses, heavy machinery and the like. The pneumatic tire 101 includes a crown portion 102, a tire buttress portion 110 that is continuous with a side edge of the crown portion 102, a sidewall portion 103, and a bead portion 104. Further, a bead core 105 is embedded in the bead portion 104. Further, a carcass 106 provided from one bead portion 104 to the other bead portion and folded back at both ends to lock the bead core 105, and a belt layer 107 made of two plies is disposed outside the crown portion of the carcass 106. Has been. An inner liner 109 extending from one bead portion 104 to the other bead portion is disposed on the inner side in the tire radial direction of the carcass 106. The belt layer 107 has two plies made of steel cord or aramid fiber cord arranged so that the plies intersect each other so that the cord is usually 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 an angle of about 90 ° in the tire circumferential direction. In the region surrounded by the carcass and the folded portion, the bead core 105 extends from the upper end to the sidewall direction. An extending bead apex 108 is disposed. Insulation may be arranged between the inner liner 109 and the carcass 106.

  The inner liner 109 includes a portion 109 a corresponding to the tire buttress portion 110 from the bead toe portion 104 a and a portion 109 b corresponding to the crown portion 102 from the tire buttress portion 110. During tire vulcanization, a portion 109a corresponding to the tire buttress portion 110 from the bead toe portion 104a of the inner liner 109 is in contact with a first vent line of a vulcanizing bladder, which will be described later, and from the tire buttress portion 110 of the inner liner to the tire crown portion 102. The portion 109b corresponding to is in contact with a second vent line of a vulcanizing bladder described later.

  The pneumatic tire manufactured by the manufacturing method of the present invention includes a tire vulcanization bladder having a plurality of vent lines, and an inner liner 109 in contact with the outer surface of the tire vulcanization bladder. The inner liner has at least a SIBS layer containing a styrene-isobutylene-styrene triblock copolymer, and the thickness of the SIBS layer is 0.05 mm or more and 0.6 mm or less. The SIBS layer contains 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. The inner liner 109 may have at least one of an SIS layer containing a styrene-isoprene-styrene triblock copolymer and an SIB layer containing a styrene-isobutylene diblock copolymer in addition to the SIBS layer. When this SIS layer or SIB layer is included, the total thickness of the SIS layer and the SIB layer is 0.01 mm or more and 0.3 mm or less.

  The inner liner has at least one of a SIBS layer, a SIS layer containing a styrene-isoprene-styrene triblock copolymer, and a SIB layer containing a styrene-isobutylene diblock copolymer. The total thickness is 0.01 mm or more and 0.3 mm or less, and at least one of the SIBS layer, the SIS layer, and the SIB layer is 0.5% by mass of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. It may contain 40% by mass or less.

  In this way, a pneumatic tire using a tire vulcanization bladder having a plurality of vent lines for an inner liner composed of a SIBS layer or an inner liner composed of either one or both of a SIBS layer and a SIS layer or a SIB layer In the tire vulcanization process, gas is discharged between the bladder and the inner surface of the tire without damaging the inner liner, air-in, flex cracking adjustment, rolling resistance, and steering stability. It is possible to manufacture a pneumatic tire that exhibits excellent performance in terms of performance.

  Hereinafter, a tire vulcanization bladder used for manufacturing the pneumatic tire of the present invention and an inner liner positioned on the inner surface of the pneumatic tire will be described.

<Tire vulcanization bladder>
The vent line of the bladder for tire vulcanization used in the method for producing a pneumatic tire of the present invention will be described with reference to FIGS. In FIG. 2, flange portions 2a and 2b are provided at both ends of the tire vulcanizing bladder 1, and a plurality of vent lines 4 are provided from one flange portion 2a to the other flange portion 2b.

  The vent line 4 includes a first vent line 4a corresponding to the tire buttress portion from the tire bead toe portion, and a second vent line 4b corresponding to the tire crown portion from the tire buttress portion. A dotted line B indicates a boundary between the first vent line 4a and the second vent line 4b.

  In FIG. 3, the first bent line 4a has an angle α with respect to the tangent T of the portion A corresponding to the tire bead toe portion of the bladder of 60 ° or more and 90 ° or less, and preferably 80 ° or more and 90 ° or less. When the angle α is less than 60 °, the direction in which the bladder contracts and the direction of the vent line are greatly different, and there is a risk of scratches resulting from rubbing between the bladder and the inner liner. Note that since the angle α is 90 ° at the maximum with respect to the tangent line T, a value exceeding 90 ° is indicated as 180 ° − (value exceeding 90 °). Therefore, even when the angle α is greater than 90 ° and 120 ° or less, the condition that the angle α is 60 ° or more and 90 ° or less is satisfied.

  The magnitude of the angle α is preferably changed according to the material characteristics of the thermoplastic elastomer composition forming the inner liner of the tire. For example, when the melting point of the thermoplastic elastomer composition is low and the softening phenomenon of the thermoplastic elastomer is large at the end of the vulcanization process at the time of manufacturing the tire, it is preferable that the angle α is large. On the other hand, when the thermoplastic elastomer composition has a high melting point and few scratches are generated due to rubbing between the bladder and the inner liner, the size of the angle α can be reduced.

  The second vent line 4b has an angle β (shown as an angle with respect to a line T ′ parallel to the tangent line T in FIG. 3) of the portion A corresponding to the tire bead toe portion of the bladder of 40 ° or more and 90 ° or less. It is preferably 45 ° or more and 90 ° or less. When the angle β is less than 40 °, the direction in which the bladder contracts and the direction of the vent line are greatly different, and there is a risk of scratches resulting from rubbing between the bladder and the inner liner. Note that since the angle β is 90 ° at the maximum with respect to the tangent line T, a value exceeding 90 ° is indicated as 180 ° − (value exceeding 90 °). Therefore, even when the angle β is greater than 90 ° and 140 ° or less, the condition that the angle β is 40 ° or more and 90 ° or less is satisfied.

  The size of the angle β is preferably smaller than 90 ° in order to prevent disturbance of the carcass cord arrangement in the tire buttress portion.

  The angles α and β satisfy the relationship α ≧ β. If the relationship between the angle α and the angle β is α <β, the gas between the tire inner surface and the bladder may not be sufficiently discharged during the tire vulcanization process. Examples of vent lines that satisfy the conditions of the angle α and the angle β are shown in FIGS.

FIG. 4A shows a vent line when the angle α is 90 ° and the angle β is 90 °.
FIG. 4B shows a vent line when the angle α is 90 ° and the angle β is 60 °.

FIG. 4C shows a vent line when the angle α is 90 ° and the angle β is 40 °.
FIG. 4D shows a vent line when the angle α is 60 ° and the angle β is 60 °.

FIG. 4E shows a vent line when the angle α is 60 ° and the angle β is 40 °.
The shape of the groove cross section of the first vent line 4a and the second vent line 4b will be described with reference to FIG. In FIG. 5, a double arrow line W indicates the width of the groove cross section of the vent line. A double arrow line H indicates the depth of the groove cross section of the vent line. The hatched portion S indicates the groove cross-sectional area of the vent line. A double arrow D indicates a distance between two adjacent vent lines.

  In this specification, the width of the groove cross section of the first vent line and the second vent line means the width on the same plane as the surface of the groove cross section that is in contact with the mold of the bladder. Therefore, for example, the groove sections of the first vent line and the second vent line are substantially semicircular or triangular, and the width of the groove sections of the first vent line and the second vent line is large depending on the distance from the bladder surface. Even when the lengths are different, the widths of the groove cross sections of the first vent line and the second vent line mean the width on the same plane as the surface of the bladder in contact with the mold.

  The width of the groove cross section of the first vent line and the second vent line is 0.5 mm to 3.0 mm, preferably 0.5 mm to 2.0 mm. When the width of the groove cross section of the first vent line and the second vent line is less than 0.5 mm, the strength of the line having the convex shape corresponding to the concave portion of the bladder vent line formed in the inner liner is weak, There is a risk of scratches resulting from the rubbing of the inner liner. On the other hand, if the width of the groove cross section of the first vent line and the second vent line exceeds 3.0 mm, the volume of the convex portion corresponding to the concave portion of the bladder vent line formed in the inner liner increases, and the tire is reduced in weight. There is a fear that you can not.

  In the present specification, the depth of the groove cross section of the first vent line and the second vent line is the distance from the bladder surface in the direction perpendicular to the surface of the groove cross section in contact with the mold of the bladder. Means the distance of the largest part. Therefore, for example, when the groove sections of the first vent line and the second vent line are substantially semicircular or substantially triangular and the depth from the bladder surface is not constant, the first vent line and the second vent The depth of the groove cross section of the line means the distance of the portion having the largest distance from the bladder surface. Specifically, when the groove sections of the first vent line and the second vent line are substantially semicircular, the depths of the groove sections of the first vent line and the second vent line are as shown in FIG. It is indicated by a double arrow H in (e). When the shape of the groove cross section of the first vent line and the second vent line is substantially triangular, the depth of the groove cross section of the first vent line and the second vent line is the both in FIG. 5 (c) or (f). Indicated by arrow H.

  The depth of the groove cross section of the first vent line and the second vent line is 0.1 mm or more and 2.0 mm or less, and preferably 0.5 mm or more and 1.5 mm or less. If the depth of the groove cross section of the first vent line and the second vent line is less than 0.1 mm, the gas between the tire inner surface and the bladder may not be sufficiently discharged during the vulcanization process of the tire. On the other hand, if the depth of the groove cross section of the first vent line and the second vent line exceeds 2.0 mm, the volume of the convex portion corresponding to the concave portion of the bladder vent line formed in the inner liner increases, and the tire becomes light. There is a risk that it cannot be converted.

In the present specification, the groove cross-sectional areas of the first vent line and the second vent line are grooves formed on the same plane as the line forming the groove and the surface of the bladder in contact with the mold. It means the area of the portion surrounded by the line connecting the ends of the line. For example, referring to FIG. 5A, the groove sectional area S of the first vent line and the second vent line is the same as the line l ₁ forming the groove and the surface of the bladder in the groove cross section. This is the area of the portion surrounded by the line l ₂ connecting the ends of the lines forming the groove.

Groove cross-sectional area of the first vent line and second vent line is at 0.025 mm ² or more 6.0 mm ² or less, preferably 0.05 mm ² or more 5.0 mm ² or less. If the groove cross-sectional areas of the first vent line and the second vent line are less than 0.025 mm ² , the gas between the tire inner surface and the bladder may not be sufficiently discharged during the vulcanization process of the tire. On the other hand, if the groove cross-sectional area of the first vent line and the second vent line exceeds 6.0 mm ² , the volume of the convex portion corresponding to the concave portion of the bladder vent line formed in the inner liner increases, and the weight of the tire is reduced. There is a fear that you can not.

  The distance between two adjacent vent lines is not particularly limited as long as the gas between the tire inner surface and the bladder is sufficiently discharged during the vulcanization process of the tire. The distance between two adjacent vent lines is preferably, for example, 2.0 mm or more and 6.0 mm or less, and more preferably 2.5 mm or more and 5.0 mm or less. If the distance between two adjacent vent lines is less than 2.0 mm, the volume of the convex portion corresponding to the concave portion of the bladder vent line formed on the inner liner may increase, and the tire may not be reduced in weight. There is. On the other hand, if the distance between two adjacent vent lines exceeds 6.0 mm, the gas between the tire inner surface and the bladder may not be sufficiently discharged during the tire vulcanization process.

  The groove shapes of the first vent line and the second vent line are, for example, a substantially rectangular shape shown in FIG. 5A, a substantially semicircular shape shown in FIG. 5B, or a substantially rectangular shape shown in FIG. A triangular shape is preferred. Furthermore, the shape of the cross section of the groove of the first vent line and the second vent line is, for example, as shown in FIGS. It can also be.

  A vent line in which the first vent line and the second vent line produced above are different from each other in the form of the second vent line will be described with reference to FIG.

In the second vent line shown in FIG. 6, an angle with respect to the tangent line T (shown as an angle with respect to a line T ′ parallel to the tangent line T in FIG. 6) is an angle β _1. includes a vent line 4b ₁ is, and a vent line 4b ₂ is an angle beta _2. By forming two second vent lines having different angles with respect to the tangent line T, the gas discharge effect can be enhanced.

When the angle β ₁ and the angle β ₂ are β ₁ ≦ β ₂ , the angle of the angle A ₁ with respect to the tangent T of the portion A corresponding to the tire bead toe portion of the bladder is 40 ° or more and 90 ° or less, Preferably they are 45 degrees or more and 90 degrees or less. On the other hand, the angle of the angle β ₂ with respect to the tangent line T, when measured from the same direction as the angle β ₁ , is greater than 90 ° and equal to or less than 140 °, preferably greater than 90 ° and equal to or less than 135 °.

The angle α with respect to the tangent T of the portion A corresponding to the tire bead toe portion of the bladder of the first vent line, and the sizes of the angles β ₁ and β ₂ satisfy the relationship of α ≧ β ₁ and α ≧ β ₂ . If the relationship between the angles α, β ₁ , and β ₂ does not satisfy the relationship, the gas between the tire inner surface and the bladder may not be sufficiently discharged during the vulcanization process of the tire.

6A and 6B show examples of vent lines that satisfy the conditions of the angle α, the angle β _1, and the angle β ₂ described above. FIG. 6A shows a vent line when the angle α is 90 °, the angle β ₁ is 40 °, and the angle β ₂ is 140 °. FIG. 6B shows a vent line when the angle α is 60 °, the angle β ₁ is 40 °, and the angle β ₂ is 140 °.

<Inner liner>
The inner liner used in the pneumatic tire of the present invention may be a single layer polymer sheet as shown in FIG. 7 or a multilayer polymer laminate as shown in FIGS. Also good.

<Inner liner made of a single polymer sheet>
As shown in FIG. 7, the polymer sheet 10a is composed of a SIBS layer 11a containing a styrene-isobutylene-styrene triblock copolymer (hereinafter also referred to as SIBS).

(SIBS layer)
The thickness of the SIBS layer 11a is not less than 0.05 mm and not more than 0.6 mm. When the thickness of the SIBS layer 11a is less than 0.05 mm, the SIBS layer may be broken by the press pressure during vulcanization of the raw tire in which the polymer sheet is applied to the inner liner, and an air leak phenomenon may occur in the obtained tire. There is. On the other hand, if the thickness of the SIBS layer 11a exceeds 0.6 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the SIBS layer 11a is preferably 0.05 mm or more and 0.4 mm or less.

  The SIBS layer 11a can be obtained by a usual method of forming a sheet of thermoplastic resin or thermoplastic elastomer such as SIBS by extrusion molding or calendar molding.

  Referring to FIG. 1, when the polymer sheet 10a is applied to the inner liner 109 of the pneumatic tire 101, the SIBS layer 11a and the carcass 106 can be vulcanized and bonded in the vulcanization process of the tire. Therefore, since the obtained pneumatic tire 101 has the inner liner 109 and the rubber layer of the carcass 106 adhered well, it can prevent air-in and can have excellent air permeation resistance.

(Styrene-isobutylene-styrene triblock copolymer: SIBS)
Due to the isobutylene block of SIBS, the polymer sheet containing SIBS has excellent air permeation resistance. Therefore, when a polymer sheet containing SIBS is used for the inner liner, a pneumatic tire excellent in 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 sheet containing 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 sheet containing SIBS to the inner liner, conventional air permeation resistance such as halogenated butyl rubber is imparted to ensure air permeation resistance by incorporating 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 method is preferably 50,000 or more and 400,000 or less from the viewpoint 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 styrene units. The content of styrene units in SIBS is preferably 10% by mass or more and 30% by mass or less from the viewpoint of better air permeation resistance and durability.

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

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

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

  Since SIBS does not have double bonds other than aromatics in the molecule, it is more stable to ultraviolet rays and has weather resistance than a polymer having double bonds in the molecule such as polybutadiene. It is good.

(Polymer obtained by polymerizing monomer units having 4 carbon atoms)
The SIBS layer 11a includes a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. The low molecular weight component of the polymer can improve the unvulcanized adhesive strength and vulcanized adhesive strength between the SIBS layer and other polymer sheets and rubber layers without impairing the air permeation resistance derived from SIBS. . Therefore, when the SIBS layer 11a containing the polymer is used for the inner liner portion of the tire, the adhesive force with the rubber layer forming the adjacent carcass or insulation is improved, and the inner liner and the carcass or the inner liner and the inner liner are formed. The air-in phenomenon during the operation can be prevented. Further, by improving the vulcanization adhesive force between the inner liner and the carcass or between the inner liner and the insulation in this way, the rigidity between the layers can be increased, and thus the steering stability can be improved.

  The number average molecular weight determined by GPC method of the polymer obtained by polymerizing the monomer unit having 4 carbon atoms is preferably 300 or more and 3,000 or less, and more preferably 500 or more and 2,500 or less. The weight average molecular weight of the polymer by GPC method is preferably 700 or more and 100,000 or less, and more preferably 1,000 or more and 80,000 or less. The viscosity average molecular weight of the polymer by FCC method is preferably 20,000 or more and 70,000 or less, and more preferably 30,000 or more and 60,000 or less.

  Examples of the polymer obtained by polymerizing a monomer unit having 4 carbon atoms include polybutene and polyisobutylene.

  Polybutene is a copolymer having a long-chain hydrocarbon molecular structure obtained by reacting isobutene as a main monomer unit and using normal butene. As the polybutene, hydrogenated polybutene can also be used.

  Polyisobutylene is a copolymer having a long-chain hydrocarbon molecular structure obtained by polymerizing isobutene as a monomer unit.

(Configuration of SIBS layer)
The SIBS layer 11a contains 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. If the content of the polymer obtained by polymerizing the monomer unit having 4 carbon atoms is less than 0.5% by mass, the vulcanization adhesive strength with carcass or insulation may be reduced, and exceeds 40% by mass. Then, the air permeation resistance is lowered, and the viscosity is lowered, so that the extrusion processability may be deteriorated. The content of the polymer is preferably 5% by mass or more and 20% by mass or less. On the other hand, the SIBS content in the SIBS layer 11a is preferably 60% by mass or more and 99.5% by mass or less. If the SIBS content is less than 60% by mass, the air permeation resistance may be reduced. If the SIBS content exceeds 99.5% by mass, the vulcanization adhesion to carcass and insulation may be reduced. It is not preferable. The content of SIBS is more preferably 80% by mass or more and 95% by mass or less.

<Inner liner made of polymer laminate>
(Form 1)
FIG. 8 is a schematic cross-sectional view showing an example of a polymer laminate used for the inner liner of the present invention.

  The polymer laminate 10b of this embodiment has a SIBS layer 11b containing SIBS and a SIS layer 12b containing a styrene-isoprene-styrene triblock copolymer (hereinafter also referred to as SIS). The thickness of the SIBS layer 11b is 0.05 mm or more and 0.6 mm or less similarly to the above.

(SIS layer)
The thickness of the SIS layer 12b is 0.01 mm or more and 0.3 mm or less. When the thickness of the SIS layer 12b is less than 0.01 mm, the SIS layer 12b may be broken by the press pressure during vulcanization of the raw tire in which the polymer sheet is applied to the inner liner, and the vulcanization adhesive force may be reduced. . On the other hand, if the thickness of the SIS layer 12b exceeds 0.3 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the SIS layer 12b is preferably 0.05 mm or more and 0.2 mm or less. The SIS layer can be obtained by a usual method of forming a sheet of a thermoplastic resin or a thermoplastic elastomer such as extrusion molding or calendar molding of SIS.

  Referring to FIG. 1, when the polymer laminate 10b is applied to the inner liner 109 of the pneumatic tire 101, the surface where the SIBS layer 11b exists is directed to the innermost side in the tire radial direction, and the surface where the SIS layer 12b exists. When the tire is installed so as to be in contact with the carcass 106 toward the outer side in the tire radial direction, the SIS layer 12b and the carcass 106 can be vulcanized and bonded in the tire vulcanization process. Therefore, since the obtained pneumatic tire 101 has a good adhesion between the inner liner 109 and the rubber layer of the carcass 106, it can prevent air-in and has excellent air permeation resistance and durability. Can do.

(Styrene-isobutylene-styrene triblock copolymer: SIBS)
A polymer obtained by polymerizing SIBS and a monomer unit having 4 carbon atoms can be the same as described above. Therefore, a styrene-isoprene-styrene triblock copolymer will be described below.

(Styrene-isoprene-styrene triblock copolymer: SIS)
Since the isoprene block of the styrene-isoprene-styrene triblock copolymer is a soft segment, the polymer sheet containing SIS is easily vulcanized and bonded to the rubber component. Therefore, when a polymer sheet containing SIS is used for the inner liner, the inner liner is excellent in adhesion to the adjacent rubber forming the carcass and insulation, for example, so that air-in can be prevented and durability is improved. 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 method is preferably 100,000 or more and 290,000 or less. 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 styrene units in the SIS is preferably 10% by mass or more and 30% by mass or less from the viewpoints of tackiness, adhesiveness, and rubber elasticity.

  In SIS, the molar ratio of isoprene units to styrene units (isoprene units / styrene units) 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 blocks and about 50 to 1,500 for styrene blocks from the viewpoint of rubber elasticity and handling.

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

(Polymer obtained by polymerizing monomer units having 4 carbon atoms)
When the polymer laminate is thus composed of the SIBS layer 11b and the SIS layer 12b, at least one of the SIBS layer 11b and the SIS layer 12b is a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. Including from 40% by mass to 40% by mass. That is, (a) when the SIBS layer 11b includes the polymer and the SIS layer 12b does not include the polymer, (b) the SIBS layer 11b does not include the polymer, and the SIS layer 12b includes the polymer. Case (c) corresponds to the case where both the SIBS layer 11b and the SIS layer 12b contain the polymer. Of the above (a) to (c), it is preferable to use (c) from the viewpoint of high adhesive strength.

When the SIBS layer 11b includes a polymer obtained by polymerizing a monomer unit having 4 carbon atoms,
It is preferable that content of each of SIBS and the said polymer contains 0.5 mass% or more and 40 mass% or less.

  When the SIS layer 12b includes a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the content of the polymer is preferably 0.5% by mass or more and 40% by mass or less. If the content of the polymer is less than 0.5% by mass, the vulcanization adhesive strength with carcass and insulation may be reduced, and if it exceeds 40% by mass, the air permeation resistance is reduced. Since the viscosity becomes low, the extrusion processability may be deteriorated, which is not preferable. The content of the polymer is more preferably 5% by mass or more and 20% by mass or less. On the other hand, the content of SIS in the SIS layer 12b is preferably 60% by mass or more and 99.5% by mass or less. If the SIS content is less than 60% by mass, the viscosity becomes low and the extrudability may be deteriorated. If it exceeds 99.5% by mass, the vulcanization adhesive strength with carcass and insulation decreases. This is not preferable because of fear. The content of SIS is more preferably 80% by mass or more and 95% by mass or less.

(Form 2)
FIG. 9 is a schematic cross-sectional view showing an example of a polymer laminate used for the inner liner of the present invention.

  The polymer laminate 10c of this embodiment has an SIBS layer 11c containing SIBS and an SIB layer 13c containing a styrene-isobutylene diblock copolymer (hereinafter also referred to as SIB). The thickness of the SIBS layer 11c is preferably 0.05 mm or greater and 0.6 mm or less as described above.

(SIB layer)
The thickness of the SIB layer 13c is not less than 0.01 mm and not more than 0.3 mm. When the thickness of the SIB layer 13c is less than 0.01 mm, the SIB layer 13c may be broken by the press pressure during vulcanization of the raw tire in which the polymer sheet is applied to the inner liner, and the vulcanization adhesive force may be reduced. . On the other hand, if the thickness of the SIB layer 13c exceeds 0.3 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the SIB layer 13c is preferably 0.05 mm or more and 0.2 mm or less. The SIB layer can be obtained by a usual method of forming SIB into a sheet of thermoplastic resin or thermoplastic elastomer such as extrusion molding or calendar molding.

  Referring to FIG. 1, when the polymer laminate 10c is applied to the inner liner 109 of the pneumatic tire 101, the surface where the SIBS layer 11c exists is directed to the innermost side in the tire radial direction, and the surface where the SIB layer 13c exists. If the tire is installed in the tire radial direction so as to be in contact with the carcass 106, the SIB layer 13c and the carcass 106 can be vulcanized and bonded in the tire vulcanization process. Therefore, since the obtained pneumatic tire 101 has a good adhesion between the inner liner 109 and the rubber layer of the carcass 106, it can prevent air-in and has excellent air permeation resistance and durability. Can do.

(Styrene-isobutylene-styrene triblock copolymer: SIBS)
A polymer obtained by polymerizing SIBS and a monomer unit having 4 carbon atoms can be the same as described above. Accordingly, the styrene-isobutylene diblock copolymer will be described below.

(Styrene-isobutylene diblock copolymer: SIB)
Since the isobutylene block of the styrene-isobutylene diblock copolymer is a soft segment, the polymer sheet containing SIB is easily vulcanized and bonded to the rubber component. Therefore, when a polymer sheet containing SIB is used for the inner liner, the inner liner is excellent in adhesion to the adjacent rubber forming the carcass and insulation, for example, so that air-in can be prevented and durability is improved. Can be obtained.

  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 method 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 styrene units in the SIB is preferably 10% by mass or more and 35% by mass or less 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 polymerization method of vinyl compounds. For example, it can be obtained by a living cationic polymerization method.

  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 stop the reaction. , A manufacturing method of vacuum drying at 60 ° C. to obtain SIB is disclosed.

(Polymer obtained by polymerizing monomer units having 4 carbon atoms)
At least one of the above-described SIBS layer 11c and SIB layer 13c contains 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. That is, (a) when the SIBS layer 11c includes the polymer and the SIB layer 13c does not include the polymer, (b) the SIBS layer 11c does not include the polymer, and the SIB layer 13c includes the polymer. In this case, (c) the case where both the SIBS layer 11c and the SIB layer 13c contain the polymer is applicable. Of the above (a) to (c), it is preferable to use (c) from the viewpoint of high adhesive strength.

  When the SIBS layer 11c includes a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the content of each of the SIBS and the polymer is preferably 0.5% by mass or more and 40% by mass or less.

  When the SIB layer 13c contains a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the content of the polymer is preferably 0.5% by mass or more and 40% by mass or less. If the content of the polymer is less than 0.5% by mass, the vulcanization adhesive strength with carcass or insulation may be reduced, and if it exceeds 40% by mass, the air permeation resistance is reduced. Since the viscosity becomes low, the extrusion processability may be deteriorated, which is not preferable. The content of the polymer is more preferably 5% by mass or more and 20% by mass or less. On the other hand, the SIB content in the SIB layer 13c is preferably 60% by mass or more and 99.5% by mass or less. If the SIB content is less than 60% by mass, the viscosity will be low and the extrudability may be deteriorated. If it exceeds 99.5% by mass, the vulcanization adhesion with carcass and insulation will be reduced. This is not preferable because of fear. The SIB content is more preferably 80% by mass or more and 95% by mass or less.

(Form 3)
FIG. 10 is a schematic cross-sectional view showing an example of a polymer laminate used for the inner liner of the present invention.

  The polymer laminate 10d of this embodiment includes a SIBS layer 11d including SIBS, a SIS layer 12d including SIS, and a SIB layer 13d including SIB. The SIBS layer 11d, the SIS layer 12d, and the SIB layer 13d are stacked in the order described above. Has been.

  The thickness of the SIBS layer 11c is preferably 0.05 mm or greater and 0.6 mm or less. The total thickness of the SIS layer 12d and the SIB layer 13d is 0.01 mm or more and 0.3 mm or less. When the total thickness of the SIS layer 12d and the SIB layer 13d is less than 0.01 mm, the SIBS layer 12d and the SIB layer 13d are torn by the press pressure during vulcanization of the raw tire in which the polymer sheet is applied to the inner liner. There is a risk that the vulcanization adhesion will be reduced. On the other hand, if the total thickness of the SIBS layer 12d and the SIB layer 13d exceeds 0.3 mm, the tire weight increases and the fuel efficiency performance decreases. The total thickness of the SIBS layer 12d and the SIB layer 13d is preferably 0.05 mm or more and 0.2 mm or less.

  Referring to FIG. 1, when the polymer laminate 10d is applied to the inner liner 109 of the pneumatic tire 101, the surface where the SIBS layer 11d exists is directed to the innermost side in the tire radial direction, and the surface where the SIB layer 13d exists. When the tire is installed so as to be in contact with the carcass 106 toward the outer side in the tire radial direction, the SIB layer 13d and the carcass 106 can be vulcanized and bonded in the tire vulcanization process. Therefore, since the obtained pneumatic tire 101 has a good adhesion between the inner liner 109 and the rubber layer of the carcass 106, it can prevent air-in and has excellent air permeation resistance and durability. Can do.

  As the polymer obtained by polymerizing SIBS, SIS, SIB, and a monomer unit having 4 carbon atoms, the same polymers as described above can be used.

(Polymer obtained by polymerizing monomer units having 4 carbon atoms)
In the present embodiment, at least one of the SIBS layer 11d, the SIS layer 12d, and the SIB layer 13d includes 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms. That is, (a) when only the SIBS layer 11d contains the polymer, (b) when only the SIS layer 12d contains the polymer, (c) when only the SIB layer 13d contains the polymer, (d) When the SIBS layer 11d and the SIS layer 12d contain the polymer, and the SIB layer 13d does not contain the polymer, (e) the SIBS layer 11d and the SIB layer 13d contain the polymer, and the SIS layer 12d contains the polymer. (F) When the SIS layer 12d and the SIB layer 13d contain the polymer, and the SIBS layer 11d does not contain the polymer, (g) all of the SIBS layer 11d, the SIS layer 12d, and the SIB layer 13d Corresponds to the case of containing the above polymer. Of the above (a) to (g), it is preferable to use (d) from the viewpoint of high adhesive strength and low cost.

  When the SIBS layer 11d contains a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the content of each of the SIBS and the copolymer can be the same as that of the polymer sheet.

  When the SIS layer 12d contains a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the contents of each of the SIS and the polymer can be the same as in the first embodiment.

  In the case where the SIB layer 13d contains a polymer obtained by polymerizing a monomer unit having 4 carbon atoms, the contents of SIB and each of the above polymers can be the same as those in the second embodiment.

(Form 4)
FIG. 11 is a schematic cross-sectional view showing an example of a polymer laminate used for the inner liner of the present invention.

  The polymer laminate 10e of this embodiment includes an SIBS layer 11e including SIBS, an SIB layer 13e including SIB, and an SIS layer 12e including SIS, and the SIBS layer 11e, SIB layer 13e, and SIS layer 12e are stacked in the above order. Has been. At least one of the SIBS layer 11e, the SIS layer 12e, and the SIB layer 13e contains 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms.

  The polymer laminate 10e of this embodiment can have the same configuration as that of Embodiment 3 except that the stacking order of the SIS layer and the SIB layer is different.

<Method for producing polymer laminate>
The polymer laminate in one embodiment of the present invention can be obtained by co-extrusion of SIBS, SIS, and SIB pellets using a T-die extruder. For example, the SIBS layer, the SIS layer, and the SIB layer can be obtained by laminate extrusion such as laminate extrusion or coextrusion in the order described in any one of the forms 2 to 4.

<Pneumatic tire manufacturing method>
The manufacturing method of the pneumatic tire of the present invention can be manufactured by the following method.

  A raw tire is produced by applying the polymer sheet or polymer laminate produced above to the inner liner part. When the polymer laminate is used, the second layer is arranged outward in the tire radial direction so as to be in contact with the carcass and the insulation. When arranged in this manner, in the tire vulcanization step, the second layer and an adjacent member such as carcass or insulation can be vulcanized and bonded. Therefore, in the obtained pneumatic tire, since the inner liner is well bonded to the adjacent member, it can have excellent air permeation resistance and durability.

  Next, the green tire is mounted on a mold, heated and pressed at 150 to 180 ° C. for 3 to 50 minutes using a tire vulcanizing bladder constituting the pneumatic tire of the present invention, and pressed. It is preferable to remove the bladder from the vulcanization mold after cooling the bladder at 50 to 120 ° C. for 10 to 300 seconds without removing it from the vulcanization mold.

  The pneumatic tire uses the polymer sheet or polymer laminate as an inner liner. Since SIBS, SIS, SIB and the like constituting the polymer sheet or polymer laminate are thermoplastic elastomers, when heated to, for example, 150 to 180 ° C. in the process of obtaining a vulcanized tire, Become. Since the thermoplastic elastomer in the softened state is more reactive than the solid state, it is fused to the adjacent member. That is, the inner liner in contact with the outer surface of the expanded bladder is softened by heating and fused to the bladder. If an attempt is made to remove the vulcanized tire from the mold while the inner liner and the outer surface of the bladder are fused, the inner liner peels off from the adjacent insulation or carcass, resulting in an air-in phenomenon. In addition, the tire shape itself may be deformed.

  Therefore, after pressurization and vulcanization, the temperature in the bladder is immediately quenched at 120 ° C. or lower for 10 seconds or more while keeping the pressurized state without opening the vulcanization mold, and used for the inner liner. The thermoplastic elastomer can be solidified. When the thermoplastic elastomer is solidified, the fusion between the inner liner and the bladder is eliminated, and the releasability when the vulcanized tire is taken out from the mold is improved.

  The cooling temperature is preferably 50 to 120 ° C. When the cooling temperature is lower than 50 ° C., it is necessary to prepare a special cooling medium, which may deteriorate productivity. When the cooling temperature exceeds 120 ° C., the thermoplastic elastomer is not sufficiently cooled, and the inner liner remains fused to the bladder when the mold is opened, which may cause an air-in phenomenon. The cooling temperature is more preferably 70 to 100 ° C.

  The cooling time is preferably 10 to 300 seconds. If the cooling time is shorter than 10 seconds, the thermoplastic elastomer is not sufficiently cooled, and the inner liner remains fused to the bladder when the mold is opened, which may cause an air-in phenomenon. When the cooling time exceeds 300 seconds, the productivity is deteriorated. The cooling time is more preferably 30 to 180 seconds.

  The step of cooling the vulcanized tire is preferably performed by cooling the inside of the bladder. Since the inside of the bladder is hollow, the cooling medium adjusted to the cooling temperature can be introduced into the bladder without lowering the bladder internal pressure after the normal vulcanization step.

  When moving to the cooling step at the end of pressurization / heating, it is preferable to move to the cooling step without lowering the bladder internal pressure. This is because if the pressure inside the bladder is lowered after the pressurization and heating, the thermoplastic elastomer is in a softened state, and there is a risk that the gauge changes, deforms, or voids occur due to the pressure drop. The process of cooling the vulcanized tire can be performed by cooling the inside of the bladder and installing a cooling structure in the mold.

  As the cooling medium, it is preferable to use one or more selected from the group consisting of air, water vapor, water, and oil. Among these, it is preferable to use water that is excellent in cooling efficiency.

<Examples 1-35 and Comparative Examples 1-9>
(Production of polymer sheet and polymer laminate)
Each compounding agent was put into a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 200 ° C.) according to the formulation shown in Table 1, and kneaded at 200 rpm to form pellets (Production Example 1). -Production Example 8). The obtained pellets were put into a co-extruder (cylinder temperature: 200 ° C.) to produce polymer sheets or polymer laminates having the structures shown in Tables 3 to 6.

(Note 1) SIBS: “Sibstar SIBSTAR 102T” manufactured by Kaneka Corporation (styrene-isobutylene-styrene triblock copolymer, weight average molecular weight 100,000, styrene unit content 25 mass%, Shore A hardness 25) .
(Note 2) SIS: “D1161JP” manufactured by Kraton Polymer Co., Ltd. (styrene-isoprene-styrene triblock copolymer, weight average molecular weight 150,000, styrene unit content 15 mass%).
(Note 3) SIB: 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 to a 2 L reaction vessel equipped with a stirrer. After cooling the reaction vessel to −70 ° C., 0.35 mL of α-picoline (2-methylpyridine) and 179 mL of isobutylene were added. Further, 9.4 mL of titanium tetrachloride was added to initiate polymerization, and the 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 is added to a methanol mixture to precipitate a polymer, and the obtained polymer is dried at 60 ° C. for 24 hours to obtain a styrene-isobutylene diblock copolymer (weight average molecular weight 70,000, styrene unit content). 15% by mass) was obtained.
(Note 4): Polyisobutylene: “Tetrax 3T” manufactured by Nippon Oil Corporation (weight average molecular weight 49,000, viscosity average molecular weight 30,000).

<Manufacture of pneumatic tires>
The obtained polymer sheet or polymer laminate was applied to the inner liner portion of the pneumatic tire to prepare a green tire. In addition, the polymer laminated body was arrange | positioned so that a 1st layer might be arrange | positioned inside the radial direction of a green tire, and a 2nd layer might contact | connect the carcass layer of a green tire. The raw tire was press-molded at 170 ° C. for 20 minutes using a tire vulcanization bladder having a bladder vent line having the shape shown in Tables 3 to 6 in the mold without opening the vulcanization mold. After cooling at 100 ° C. for 3 minutes without lowering the internal pressure of the bladder, the vulcanized tire was taken out of the mold, and a 195 / 65R15 size vulcanized tire was manufactured to obtain a pneumatic tire.

The following evaluation was performed using the obtained pneumatic tire.
((A) First layer vulcanization adhesion)
The unvulcanized rubber sheets of the first layer and the carcass layer, and the first layer and the second layer are bonded together and heated at 170 ° C. for 20 minutes to prepare a sample for measuring the vulcanized adhesive force. The peel strength was measured by a tensile peel test to obtain a vulcanized adhesive strength. The obtained numerical values were indexed by the following formula for the vulcanization adhesive strength of the first layer of each example and each comparative example with Example 1 as a reference (100). In addition, it shows that vulcanization adhesive force is so strong that a numerical value is large, and preferable.
(Vulcanization adhesion index) = (Vulcanization adhesion of each example and each comparative example) / (Vulcanization adhesion of Example 1) × 100.

((B) Inner liner damage)
The inner liner of the vulcanized tire was visually inspected for damage. Judgment criteria are as follows. The magnitude of damage is not considered.
A: The number of damage of the inner liner per tire is zero in appearance.
B: The number of damage of the inner liner per tire is one or more in appearance.

((C) Air-in presence / absence)
The inside of the tire after the vulcanization and cooling process was inspected and evaluated according to the following criteria.
A: From the appearance, the number of air-ins having a diameter of 5 mm or less per tire is 0, and the number of air-ins having a diameter exceeding 5 mm is 0.
B: From the appearance, the number of air-ins having a diameter of 5 mm or less per tire is 1 to 3 and the number of air-ins having a diameter exceeding 5 mm is 0.
C: In terms of appearance, the number of air-ins having a diameter of 5 mm or less per tire is 4 or more, or the number of air-ins having a diameter of 5 mm or more is 1 or more.

((D) Flex crack growth index)
In the tire durability running test, it was evaluated whether the inner liner was cracked or peeled off. The manufactured 195 / 65R15 size pneumatic tire is assembled to a JIS standard rim 15 × 6JJ, the tire internal pressure is 150 KPa which is lower than usual, the load is 600 kg, the speed is 100 km / hour, and the traveling distance is 20,000 km. The inside of the tire was observed and the number of crack peeling was measured. The obtained numerical value was expressed as an index according to the following formula for the flex crack growth properties of each example and each comparative example, with Example 1 as a reference (100). The larger the value, the better the flex crack growth resistance.
(Bending crack growth index) = (Number of crack peeling in Example 1) / (Number of crack peeling in each example and each comparative example) × 100.

((E) Rolling resistance)
Using a rolling resistance tester manufactured by Kobe Steel Co., Ltd., the manufactured 195 / 65R15 size pneumatic tire was assembled into a JIS standard rim 15 × 6JJ, under conditions of a load of 3.4 kN, an air pressure of 230 kPa, and a speed of 80 km / hour. Then, the rolling resistance was measured by running at room temperature (38 ° C.). The obtained numerical value was expressed as an index according to the following formula for the rolling resistance of each example and each comparative example, with Example 1 as a reference (100). In addition, it shows that rolling resistance is reduced and it is so preferable that a numerical value is large.
(Rolling resistance index) = (Rolling resistance of Example 1) / (Rolling resistance of each example and each comparative example) × 100.

((F) Steering stability)
Pneumatic tires were installed on all the domestic FF2000cc wheels and the vehicle was run on the test course, and the steering stability was evaluated by sensory evaluation of the driver. At that time, relative evaluation was performed with 10 points being a perfect score and Example 1 being 6 points. The larger the value, the better the steering stability.

(Comprehensive judgment)
Table 2 shows the criteria for comprehensive judgment.

(Evaluation results)
The results are shown in Tables 3 to 6.

(Contrast with Examples 1-8 and Comparative Examples 1-4)
The groove sections of the first vent line and the second vent line of the pneumatic tire manufactured in Examples 1 to 8 have a width of 0.5 mm or more and 3.0 mm or less on the surface in contact with the mold of the bladder. the depth from the surface of the mold in contact with the side is at 0.1mm or 2.0mm or less, and groove cross-sectional area of the first vent line and second vent line is 0.025 mm ² or more 6.0 mm ² or less there were.

In contrast, the groove sections of the first and second vent lines of the pneumatic tires manufactured in Comparative Examples 1, 2, and 4 have a width of 0.5 mm on the surface on the side in contact with the mold of the bladder. The depth from the surface on the side in contact with the mold of the bladder was less than 0.1 mm, and the groove sectional areas of the first vent line and the second vent line were less than 0.025 mm ² . Further, the shape of the groove cross section of the first vent line and the second vent line of the pneumatic tire manufactured in Comparative Example 3 is such that the width on the surface on the side in contact with the mold of the bladder exceeds 3.0 mm. The depth from the surface in contact with the mold exceeded 2.0 mm, and the groove sectional areas of the first vent line and the second vent line exceeded 6.0 mm ² .

  For this reason, the pneumatic tire manufactured in Examples 1-8 showed the performance excellent in the air-in, bending cracking adjustment, rolling resistance, and steering stability compared with that of Comparative Examples 1-4.

(Contrast with Examples 1 to 8 and Comparative Example 5)
In the pneumatic tires manufactured in Examples 1 to 8, the angle α of the first vent line with respect to the tangent of the part corresponding to the tire bead toe part and the angle of the second vent line with respect to the tangent of the part corresponding to the tire bead toe part Whereas β satisfied the relationship of α ≧ β, the pneumatic tire manufactured in Comparative Example 5 did not satisfy the relationship of α ≧ β.

  For this reason, the pneumatic tires of Examples 1 to 8 showed superior performance in air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 5.

(Contrast with Examples 1-8 and Comparative Example 6)
The pneumatic tires manufactured in Examples 1 to 8 were manufactured in Comparative Example 6 while the angle α of the first vent line with respect to the tangent of the portion corresponding to the tire bead toe portion was 60 ° or more and 90 ° or less. In the pneumatic tire, the angle α of the first vent line with respect to the tangent of the portion corresponding to the tire bead toe portion was less than 60 °.

  For this reason, the pneumatic tire manufactured in Examples 1-8 showed the performance excellent in the air-in, bending crack property adjustment, rolling resistance, and steering stability compared with the comparative example 6.

(Contrast with Examples 12 to 13 and Comparative Example 7)
The groove sections of the first vent line and the second vent line of the pneumatic tire manufactured in Examples 12 to 13 have a width of 0.5 mm or more and 3.0 mm or less on the surface in contact with the mold of the bladder. the depth from the surface of the mold in contact with the side is at 0.1mm or 2.0mm or less, and groove cross-sectional area of the first vent line and second vent line is 0.025 mm ² or more 6.0 mm ² or less there were.

In contrast, the shape of the groove cross section of the first vent line and the second vent line of the pneumatic tire manufactured in Comparative Example 7 is such that the width on the surface in contact with the mold of the bladder exceeds 3.0 mm. The depth from the surface in contact with the mold exceeded 2.0 mm, and the groove sectional areas of the first vent line and the second vent line exceeded 6.0 mm ² .

  For this reason, the pneumatic tires of Examples 12 to 13 exhibited superior performance in terms of air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 7.

(Contrast with Examples 14 to 24 and Comparative Example 8)
In the pneumatic tires manufactured in Examples 14 to 24, the angle α of the first vent line with respect to the tangent of the part corresponding to the tire bead toe part and the angle of the second vent line with respect to the tangent of the part corresponding to the tire bead toe part Whereas β satisfied the relationship of α ≧ β, the pneumatic tire manufactured in Comparative Example 8 did not satisfy the relationship of α ≧ β.

  For this reason, the pneumatic tires manufactured in Examples 14 to 24 showed superior performance in air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 8.

(Contrast with Examples 25-35 and Comparative Example 9)
In the pneumatic tires manufactured in Examples 25 to 35, the angle α of the first vent line with respect to the tangent of the part corresponding to the tire bead toe part and the angle of the second vent line with respect to the tangent of the part corresponding to the tire bead toe part Whereas β satisfied the relationship of α ≧ β, the pneumatic tire manufactured in Comparative Example 9 did not satisfy the relationship of α ≧ β.

  For this reason, the pneumatic tire manufactured in Examples 25-35 showed the performance excellent in the air-in, bending cracking adjustment, rolling resistance, and steering stability compared with the comparative example 9.

  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 Tire vulcanizing bladder, 2a, 2b flange part, 4 vent line, 4a 1st vent line, 4b 2nd vent line, 10a polymer sheet, 10b, 10c, 10d, 10e polymer laminated body, 11a, 11b, 11c, 11d, 11e SIBS layer, 12b, 12d, 12e SIS layer, 13c, 13d, 13e SIB layer, 20, 30, 40 Polymer sheet, 21, 31, 41 First layer, 32, 42 Second layer, 42a Second a layer , 42b 2b layer, 101 pneumatic tire, 102 crown portion, 103 sidewall portion, 104 bead portion, 104a bead toe portion, 105 bead core, 106 carcass, 107 belt layer, 108 bead apex, 109 inner liner, 110 tire buttress portion .

< Reference Examples 1-21, Examples 9 , 11-13, 19, 20, 22-24, 30, 31, and 33-35, Comparative Examples 1-9>
(Production of polymer sheet and polymer laminate)
Each compounding agent was put into a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 200 ° C.) according to the formulation shown in Table 1, and kneaded at 200 rpm to form pellets (Production Example 1). -Production Example 8). The obtained pellets were put into a co-extruder (cylinder temperature: 200 ° C.) to produce polymer sheets or polymer laminates having the structures shown in Tables 3 to 6.

The following evaluation was performed using the obtained pneumatic tire.
((A) First layer vulcanization adhesion)
The unvulcanized rubber sheets of the first layer and the carcass layer, and the first layer and the second layer are bonded together and heated at 170 ° C. for 20 minutes to prepare a sample for measuring the vulcanized adhesive force. The peel strength was measured by a tensile peel test to obtain a vulcanized adhesive strength. The obtained numerical values were indexed by the following formula for the vulcanization adhesive strength of the first layer of each example, each comparative example , and each reference example with reference example 1 as a reference (100). In addition, it shows that vulcanization adhesive force is so strong that a numerical value is large, and preferable.
(Vulcanization adhesion index) = (Vulcanization adhesion of each example, each comparative example , each reference example ) / (Vulcanization adhesion of Reference example 1) × 100.

((D) Flex crack growth index)
In the tire durability running test, it was evaluated whether the inner liner was cracked or peeled off. The manufactured 195 / 65R15 size pneumatic tire is assembled to a JIS standard rim 15 × 6JJ, the tire internal pressure is 150 KPa which is lower than usual, the load is 600 kg, the speed is 100 km / hour, and the traveling distance is 20,000 km. The inside of the tire was observed and the number of crack peeling was measured. The obtained values are reported as a reference (100) Reference Example 1, the Examples, Comparative Examples, the flex crack growth resistance of each Example was indexed to the following formula. The larger the value, the better the flex crack growth resistance.
(Bending crack growth index) = (number of crack peeling in reference example 1) / (number of crack peeling in each example, each comparative example , each reference example ) × 100.

((E) Rolling resistance)
Using a rolling resistance tester manufactured by Kobe Steel Co., Ltd., the manufactured 195 / 65R15 size pneumatic tire was assembled into a JIS standard rim 15 × 6JJ, under conditions of a load of 3.4 kN, an air pressure of 230 kPa, and a speed of 80 km / hour. Then, the rolling resistance was measured by running at room temperature (38 ° C.). The obtained numerical values were represented by the following formula as an index for the rolling resistance of each example, each comparative example , and each reference example with reference example 1 as the reference (100). In addition, it shows that rolling resistance is reduced and it is so preferable that a numerical value is large.
(Rolling resistance index) = (Rolling resistance of Reference Example 1) / (Rolling resistance of each Example, each Comparative Example , each Reference Example ) × 100.

(Contrast with Reference Examples 1-8 and Comparative Examples 1-4)
The groove sections of the first vent line and the second vent line of the pneumatic tire manufactured in Reference Examples 1 to 8 have a width of 0.5 mm or more and 3.0 mm or less on the surface in contact with the mold of the bladder. the depth from the surface of the mold in contact with the side is at 0.1mm or 2.0mm or less, and groove cross-sectional area of the first vent line and second vent line is 0.025 mm ² or more 6.0 mm ² or less there were.

For this reason, the pneumatic tire manufactured by Reference Examples 1-8 showed the performance excellent in the air-in, bending crack property adjustment, rolling resistance, and steering stability compared with that of Comparative Examples 1-4.

(Contrast with Reference Examples 1 to 8 and Comparative Example 5)
In the pneumatic tires manufactured in Reference Examples 1 to 8, the angle α of the first vent line with respect to the tangent of the part corresponding to the tire bead toe part and the angle of the second vent line with respect to the tangent of the part corresponding to the tire bead toe part Whereas β satisfied the relationship of α ≧ β, the pneumatic tire manufactured in Comparative Example 5 did not satisfy the relationship of α ≧ β.

For this reason, the pneumatic tires of Reference Examples 1 to 8 showed superior performance in terms of air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 5.

(Contrast with Reference Examples 1 to 8 and Comparative Example 6)
The pneumatic tires manufactured in Reference Examples 1 to 8 were manufactured in Comparative Example 6 while the angle α of the first vent line with respect to the tangent of the portion corresponding to the tire bead toe portion was 60 ° or more and 90 ° or less. In the pneumatic tire, the angle α of the first vent line with respect to the tangent of the portion corresponding to the tire bead toe portion was less than 60 °.

For this reason, the pneumatic tires manufactured in Reference Examples 1 to 8 showed superior performance in air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 6.

(Contrast with Reference Examples 10 to 15, Examples 19 , 20 , 22 to 24 and Comparative Example 8)
In the pneumatic tires manufactured in Examples 19 , 20 , 22 to 24 , the angle α of the first vent line with respect to the tangent of the part corresponding to the tire bead toe part and the second to the tangent of the part corresponding to the tire bead toe part While the angle β of the vent line satisfied the relationship of α > β, the pneumatic tire manufactured in Comparative Example 8 did not satisfy the relationship of α > β.

For this reason, the pneumatic tires manufactured in Examples 19 , 20 , and 22-24 show superior performance in air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 8. It was.

(Comparison between Reference Examples 16 to 21, Examples 30, 31, and 35 and Comparative Example 9)
In the pneumatic tire manufactured in Examples 30, 31, and 35, the angle α of the first vent line with respect to the tangent of the portion corresponding to the tire bead toe portion and the second vent line with respect to the tangent of the portion corresponding to the tire bead toe portion while the angle beta is satisfied the relationship of alpha> beta, a pneumatic tire prepared in Comparative example 9 did not satisfy the relation of the alpha> beta.

For this reason, the pneumatic tires manufactured in Examples 30, 31, and 35 showed superior performance in air-in, flex cracking adjustment, rolling resistance, and steering stability as compared with Comparative Example 9.

Claims (11)

Using a tire vulcanization bladder with a plurality of vent lines, a method for producing a pneumatic tire with an inner liner on the inner surface,
The inner liner has a SIBS layer containing a styrene-isobutylene-styrene triblock copolymer,
The thickness of the SIBS layer is 0.05 mm or more and 0.6 mm or less,
The SIBS layer contains 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms,
The vent line includes a first vent line corresponding to the tire buttress portion from the tire bead toe portion, and a second vent line corresponding to the tire crown portion from the tire buttress portion,
The groove sections of the first vent line and the second vent line have a width of 0.5 mm to 3.0 mm on the surface of the tire vulcanization bladder in contact with the mold, and the tire vulcanization gold. The depth from the surface on the side in contact with the mold is 0.1 mm or more and 2.0 mm or less,
Groove cross-sectional area of the first vent line and second vent line is at 0.025 mm ² or more 6.0 mm ² or less,
The first vent line has an angle α with respect to a tangent of a portion corresponding to the tire bead toe portion of 60 ° or more and 90 ° or less, and the second vent line is with respect to a tangent of a portion corresponding to the tire bead toe portion. The angle β is 40 ° or more and 90 ° or less,
The method of manufacturing a pneumatic tire, wherein the angle α and the angle β satisfy a relationship of α ≧ β. Using a tire vulcanization bladder with a plurality of vent lines, a method for producing a pneumatic tire with an inner liner on the inner surface,
The inner liner includes at least a SIBS layer containing a styrene-isobutylene-styrene triblock copolymer, a SIS layer containing a styrene-isoprene-styrene triblock copolymer, and a SIB layer containing a styrene-isobutylene diblock copolymer. Have either
The thickness of the SIBS layer is 0.05 mm or more and 0.6 mm or less,
The total thickness of the SIS layer and the SIB layer is 0.01 mm or more and 0.3 mm or less,
At least one of the SIBS layer, the SIS layer, and the SIB layer includes 0.5% by mass or more and 40% by mass or less of a polymer obtained by polymerizing a monomer unit having 4 carbon atoms,
The vent line includes a first vent line corresponding to the tire buttress portion from the tire bead toe portion, and a second vent line corresponding to the tire crown portion from the tire buttress portion,
The shape of the groove cross section of the first vent line and the second vent line is such that the width on the surface in contact with the mold of the bladder is 0.5 mm to 3.0 mm and the surface on the side in contact with the mold of the bladder. The depth is 0.1 mm or more and 2.0 mm or less,
Groove cross-sectional area of the first vent line and second vent line is at 0.025 mm ² or more 6.0 mm ² or less,
The first vent line has an angle α with respect to a tangent of a portion corresponding to the tire bead toe portion of 60 ° or more and 90 ° or less, and the second vent line is with respect to a tangent of a portion corresponding to the tire bead toe portion. The angle β is 40 ° or more and 90 ° or less,
The method of manufacturing a pneumatic tire, wherein the angle α and the angle β satisfy a relationship of α ≧ β.   3. The method for manufacturing a pneumatic tire according to claim 1, wherein a shape of a groove cross section of each of the first vent line and the second vent line is a substantially rectangular shape, a substantially semicircular shape, or a substantially triangular shape.   The method for producing a pneumatic tire according to claim 2 or 3, wherein the polymer obtained by polymerizing the monomer unit having 4 carbon atoms comprises at least one of polybutene and polyisobutylene.   The polymer obtained by polymerizing the monomer unit having 4 carbon atoms has a number average molecular weight of 300 to 3,000, a weight average molecular weight of 700 to 100,000, and a viscosity average molecular weight of 20,000 to 70,000. The manufacturing method of the pneumatic tire in any one of Claims 2-4 which satisfy | fills at least one.   The manufacturing method of the pneumatic tire in any one of Claims 2-5 by which the said SIBS layer is arrange | positioned inside the radial direction of a pneumatic tire.   An SIS layer containing a polymer obtained by polymerizing the monomer unit having 4 carbon atoms or an SIB layer containing a polymer obtained by polymerizing the monomer unit having 4 carbon atoms is in contact with the carcass layer of the pneumatic tire. The manufacturing method of the pneumatic tire in any one of Claims 2-6 arrange | positioned.   The styrene-isobutylene-styrene triblock copolymer has a weight average molecular weight of 50,000 or more and 400,000 or less, and a styrene unit content of 10% by mass or more and 30% by mass or less. A method for producing a pneumatic tire according to claim 1.   The styrene-isoprene-styrene triblock copolymer has a weight average molecular weight of 100,000 or more and 290,000 or less, and a styrene unit content of 10% by mass or more and 30% by mass or less. The manufacturing method of the pneumatic tire of description.   The styrene-isobutylene diblock copolymer is linear, has a weight average molecular weight of 40,000 to 120,000, and a styrene unit content of 10% by mass to 35% by mass. The method for producing a pneumatic tire according to any one of 7.   The inner liner further comprises a layer 2a composed of a 2a thermoplastic elastomer composition containing a styrene-isoprene-styrene triblock copolymer, and a 2b thermoplastic elastomer composition containing a styrene-isobutylene diblock copolymer. The manufacturing method of the pneumatic tire in any one of Claims 2-10 provided with the 2nd layer containing at least any 2nd layer which becomes.

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