JP2016064810A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire with improved durability while maintaining excellent air permeability resistance and good rolling resistance.SOLUTION: A pneumatic tire comprises a carcass layer, an inner liner layer arranged in the tire inside of the carcass layer, and a rubber layer arranged in the tire inside of the inner liner layer. The inner liner layer is a polymer layer with a thickness of 0.05 - 0.5 mm containing SIBS and tackifier arranged so as to be in contact with the carcass layer, and includes the polymer layer containing 99 - 50 mass% of SIBS and 1 - 50 mass% of tackifier to the total amount of the SIBS and the tackifier. The pneumatic tire satisfies at least either of the conditions (a) the inner liner layer includes a first region, and a second layer which is a region different from the first region and whose thickness is larger than that of the first region, and (b) the rubber region includes a third region, and a fourth region which is a region different from the third region and whose thickness is larger than that of the third region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire including an inner liner layer and a rubber layer that are formed of a thermoplastic resin layer.

  The inner liner layer is a tire member that is disposed inside the pneumatic tire and plays a role of improving air permeation resistance by reducing the amount of air leakage (air permeation amount) from the inside of the tire to the outside.

  The inner liner layer is required to have durability as well as air permeation resistance. This is because the inner liner layer is a member that is likely to be damaged due to contact with tools during rim assembling work or the like, and is also easily damaged when buffing the tire inner surface in puncture repair or the like. Damage to the inner liner layer can greatly reduce the air permeation resistance of the tire.

  Further, in recent years, tires have been required to be reduced in weight due to the strong social demand for lower fuel consumption of vehicles, and the inner liner layer, which is one member, is also required to be reduced in weight. Conventionally, the inner liner layer of tubeless pneumatic tires has generally used butyl rubber, which has a relatively high resistance to air permeation. However, since butyl rubber has a high specific gravity, the tire is heavier. As a result, the rolling resistance increased, which contributed to the deterioration of fuel consumption.

  In order to improve the characteristics of the inner liner layer, various techniques have been conventionally proposed (Patent Documents 1 to 6).

JP 08-258506 A JP 09-019987 A JP 2000-159936 A JP 2008-024219 A JP 2005-343379 A JP 2009-279977 A

  Patent Document 1 describes that a film made of a thermoplastic resin such as polyvinylidene chloride is used for an inner liner layer (air permeation preventive layer) of a pneumatic tire. Thermoplastic resin is superior in air permeation resistance compared to butyl rubber, and according to the inner liner layer to which this is applied, the weight of the tire is reduced compared to when butyl rubber is used. Is also possible.

  However, the inner liner layer made of a thermoplastic resin needs to be extremely thin in order to ensure the bending fatigue resistance, and thus is easily damaged in the above-described scene. In addition, since a large shear strain acts in the vicinity of the shoulder portion when using the tire, there is a problem in that peeling is likely to occur at the adhesive interface between the inner liner layer and the carcass layer, and air leakage of the tire is likely to occur.

  Patent Document 2 discloses a laminate comprising a laminated film (inner liner layer) comprising a gas barrier layer (A) and adhesive layers (B) disposed on both sides thereof, and a rubber layer (R) such as a carcass layer. A laminate in which the adhesive layer (B) and the rubber layer (R) are heated and bonded is described. By providing the adhesive layer (B) on both sides of the gas barrier layer (A), the inner layer is formed. It is stated that the adhesive layers (B) come into contact with each other at the overlapping portion of the liner layer and are firmly bonded by heating, so that the air pressure retention can be improved. However, the adhesive layer (B) for overlapping the inner liner layer comes into contact with the bladder in an overheated state in the vulcanization process, and there is a problem of sticking to the bladder.

  In Patent Document 3, a thermoplastic elastomer composition having a matrix composed of a thermoplastic resin composition (B) composed of a blend of two or more thermoplastic resins as a dispersed phase is used as an elastomer composition (A) in a pneumatic tire. It is described that it is used for a permeation preventive layer. Nylon resin is used for the two or more thermoplastic resins.

  However, since the nylon resin is hard at room temperature, the thermoplastic elastomer composition described in the document is unsuitable as an inner liner layer of a pneumatic tire. Further, since this thermoplastic elastomer composition cannot be vulcanized and bonded to a rubber layer such as a carcass layer, if this thermoplastic elastomer composition is used for an inner liner layer, it is bonded to the rubber layer. It is necessary to separately provide a vulcanization adhesive layer for the purpose. For this reason, the tire structure and the tire manufacturing process are complicated, which is disadvantageous from the viewpoint of productivity.

  In Patent Document 4, a thermoplastic urethane elastomer layer is provided on both sides of an ethylene-vinyl alcohol copolymer layer in which a flexible resin such as maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer is dispersed. There is described an inner liner layer formed by laminating and laminating this laminated body to a rubber-like elastic body layer using an adhesive composition containing butyl rubber or the like.

  However, since the ethylene-vinyl alcohol copolymer in which the flexible resin is dispersed has low adhesive force, it tends to be peeled off from the thermoplastic urethane-based elastomer layer. In addition, although the flexible resin is dispersed, the ethylene-vinyl alcohol copolymer that is the matrix itself has poor bending fatigue resistance, so the inner liner layer described in the document still has room for improvement with respect to bending resistance. there were. Furthermore, a separate process of adhering the laminate to the rubber-like elastic layer using an adhesive composition is necessary, which is disadvantageous from the viewpoint of productivity.

  Patent Document 5 discloses that in an inner liner layer made of a thermoplastic resin containing a rubber composition, low-temperature durability can be improved by making the thickness dimension at the shoulder portion larger than the thickness dimension at the tire crown portion. Is described.

  However, increasing the thickness dimension of a part of the inner liner layer increases the weight of the pneumatic tire, and consequently increases the rolling resistance of the tire, which causes a deterioration in fuel consumption.

  In Patent Document 6, a thermoplastic resin film layer (inner liner layer) made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer in a thermoplastic resin is provided on the inner surface of a tire, and the inner surface of the thermoplastic resin film layer In the structure in which the protective rubber layer is laminated, it is described that by changing the thickness of at least one of the thermoplastic resin film layer or the protective rubber layer, damage to the inner liner portion in the above-described scene can be prevented. Yes. However, the concern about the deterioration of fuel consumption caused by thickening a part of the inner liner layer is the same as that of the invention described in Patent Document 5, and there is still room for improvement in terms of tire durability.

  Accordingly, an object of the present invention is to provide a tire with improved durability while maintaining excellent air permeation resistance and good rolling resistance.

The present invention
[1] carcass layer,
A pneumatic tire comprising an inner liner layer disposed inside the tire of the carcass layer, and a rubber layer disposed inside the tire of the inner liner layer,
The inner liner layer is a polymer layer having a thickness of 0.05 to 0.5 mm containing a styrene-isobutylene-styrene triblock copolymer and a tackifier disposed so as to be in contact with the carcass layer. 99-50 mass% of styrene-isobutylene-styrene triblock copolymer is preferable with respect to the total amount of an isobutylene-styrene triblock copolymer and a tackifier, More preferably, it is 95-60 mass%. 80% by weight, including a polymer layer containing 1-50% by weight of a tackifier, preferably 5-45% by weight, more preferably 10-40% by weight,
Next (a) and (b):
(A) the inner liner layer includes a first region and a second region that is different from the first region and is thicker than the first region; and (b) the rubber layer includes A pneumatic tire that satisfies at least one of the third region and a fourth region that is different from the third region and has a thickness greater than that of the third region;
[2] The first region is a region corresponding to a tread portion in the inner liner layer, and the second region is at least a part of the inner liner layer other than the first region. 1] The pneumatic tire according to
[3] The above [1] or [4], wherein the fourth region is a region corresponding to a tread portion in the rubber layer, and the third region is all regions other than the fourth region in the rubber layer. 2] Pneumatic tire according to
[4] The tackifier is C9 petroleum resin, C5 petroleum resin, terpene resin, aromatic modified terpene resin, terpene phenol resin, coumarone resin, coumarone indene oil, rosin ester, hydrogenated rosin ester, alkylphenol resin and DCPD. The pneumatic tire according to any one of the above [1] to [3], which is at least one selected from the group consisting of:
[5] The pneumatic tire according to any one of [1] to [3], wherein the tackifier is an isobutylene-based low molecular weight substance.
[6] The pneumatic tire according to any one of [1] to [3], wherein the tackifier is an epoxidized styrene-butadiene-styrene triblock copolymer, and [7] the styrene-isobutylene- The styrene triblock copolymer has a styrene component content of 10 to 40% by mass, preferably 14 to 30% by mass, and a weight average molecular weight of 50,000 to 400,000. The pneumatic tire according to any one of the above.

  According to the present invention, it is possible to provide a tire with improved durability while maintaining excellent air permeation resistance and good rolling resistance.

It is a schematic sectional drawing which shows the tire right half for demonstrating the pneumatic tire which is one embodiment of this invention.

  The present invention relates to a pneumatic tire including at least a carcass layer, an inner liner layer disposed inside the tire of the carcass layer, and a rubber layer (hereinafter also referred to as a protective rubber layer) disposed inside the tire of the inner liner layer. . The pneumatic tire may be a heavy duty pneumatic tire such as a truck or a bus, or may be a pneumatic tire for a passenger car.

  In the pneumatic tire of the present invention, the inner liner layer has a thickness of 0.05 to 0.5 mm containing a styrene-isobutylene-styrene triblock copolymer (hereinafter also referred to as “SIBS”) and a tackifier. The polymer layer is a polymer layer containing 99 to 50% by mass of SIBS and 1 to 50% by mass of the tackifier (hereinafter also simply referred to as a polymer layer) with respect to the total amount of SIBS and tackifier. And the polymer layer is disposed in contact with the carcass layer.

Moreover, the pneumatic tire of the present invention includes the following (a) and (b):
(A) the inner liner layer includes a first region and a second region that is different from the first region and has a thickness larger than the first region; and (b) the rubber layer includes The third region and the third region are different from each other and include at least one of the fourth region having a thickness larger than that of the third region.

  FIG. 1 is a schematic cross-sectional view (half-sectional view in the tire meridian direction) showing a right half of a tire for explaining a pneumatic tire (for example, a heavy-duty pneumatic tire) according to an embodiment of the present invention. However, since this figure is for grasping | ascertaining the whole image of a pneumatic tire, the matter regarding the thickness of said (a) and (b) is not reflected.

  A pneumatic tire T shown in FIG. 1 has a main groove 11 extending in the tire circumferential direction, and is formed from a crown center position A to a shoulder portion 2; a tread portion 1; a buttress portion 3 extending from the shoulder portion 2; Side wall portion 4 extending from portion 3; extending from sidewall portion 4, bead core 51 is embedded and bead portion 5 in which chafer 52 is disposed; mounted between a pair of left and right bead cores 51, and bead core 51 at both ends. A carcass layer 6 that is folded back and locked around the belt; a plurality of belt layers 7 that are disposed outside the crown portion of the carcass layer 6; and disposed between the pair of left and right bead portions 5 on the inner side in the tire radial direction of the carcass layer 6. Inner liner layer 8; a pair of left and right bead portions on the inner side in the tire radial direction of the inner liner layer 8 Containing rubber layer 9 disposed over between.

  In addition, since SIBS has a completely saturated molecular structure other than an aromatic ring, it is difficult to cause deterioration hardening and has excellent durability. Therefore, a pneumatic tire having excellent durability can be obtained by using an inner liner layer including a polymer layer containing SIBS.

  The content of SIBS in the total amount of SIBS and tackifier in the polymer layer is 50 parts by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more. Further, the SIBS content in the polymer layer is 99% by mass or less, and preferably 95% by mass or less. When the SIBS content is less than 50% by mass, the air permeation resistance and durability tend not to be sufficient, and when the SIBS content exceeds 99% by mass, the vulcanization adhesiveness tends to be insufficient. is there. Therefore, a pneumatic tire excellent in air permeability and durability can be obtained by using a polymer layer containing 60% by mass or more of SIBS.

  Thus, it is possible to obtain excellent air permeation resistance by applying an inner liner layer including a polymer layer containing SIBS. Therefore, it is not necessary to use a high specific gravity butyl rubber (such as halogenated butyl rubber) that has been conventionally used to impart air permeation resistance. As a result, the weight of the tire can be reduced, and the rolling resistance of the tire can be reduced. As a result, an improvement in fuel consumption can be obtained. Compared to the case of using a conventional inner liner layer made of other thermoplastic resins, the fuel economy can be improved by reducing the weight of the tire and reducing the rolling resistance of the tire while maintaining air resistance. In addition, it is possible to obtain an effect of improving durability.

  Although the molecular weight of SIBS is not particularly limited, the weight average molecular weight in terms of styrene by gel permeation chromatography measurement is 50, from the viewpoint of rubber elasticity and fluidity of SIBS, molding processability to polymer layer and inner liner layer, and the like. It is preferable that it is 000-400,000. If the weight average molecular weight is less than 50,000, the rubber elasticity, tensile strength and tensile elongation of SIBS may be reduced. On the other hand, when the weight average molecular weight exceeds 400,000, there is a possibility that the molding processability (extrusion processability, etc.) to the inner liner layer may decrease due to the decrease in SIBS fluidity.

  SIBS has a content of the styrene component in SIBS of preferably 10% by mass or more, and more preferably 14% by mass or more, from the viewpoint of improving air permeation resistance and durability. Moreover, it is preferable that content of the styrene component in SIBS is 40 mass% or less, and it is more preferable that it is 30 mass% or less. If the content of the styrene component is less than 10% by mass, the fuel efficiency tends to deteriorate, and if it exceeds 40% by mass, more sufficient durability tends not to be obtained.

  The molar ratio (isobutylene / styrene) between the isobutylene component and styrene constituting SIBS is preferably 40/60 to 95/5 from the viewpoint of rubber elasticity of SIBS. The degree of polymerization of each block constituting the SIBS is preferably about 10,000 to 150,000 in the case of an isobutylene block from the viewpoint of rubber elasticity and handleability of the SIBS (becomes liquid when the degree of polymerization is less than 10,000). In the styrene block, about 10,000 to 30,000 is preferable.

  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, and isobutylene as a vinyl compound and other compounds are used as living compounds. It is disclosed that a polyisobutylene block copolymer can be produced by cationic polymerization. In addition, 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, No. 174403.

  Since SIBS does not have a double bond other than an aromatic ring in the molecule as described above, it is more resistant to ultraviolet rays than a polymer having a double bond other than an aromatic ring in the molecule, such as polybutadiene. High stability and therefore good weather resistance. In addition, the refractive index (nD) at 20 ° C. of light having a wavelength of 589 nm, despite having no double bond other than an aromatic ring in the molecule and being a saturated rubbery polymer, According to the Polymer Handbook (1989, Polymer Handbook, Willy, 1989), it is 1.506. This is significantly higher than other saturated rubbery polymers such as ethylene-butene copolymers.

  In this invention, content of the tackifier in a polymer layer is 1 mass% or more with respect to the total amount of SIBS and a tackifier, 5 mass% or more is preferable, and 10 mass% or more is more preferable. Moreover, content of a tackifier is 50 mass% or less with respect to the total amount of SIBS and a tackifier, 45 mass% or less is preferable, and 40 mass% or less is more preferable. When the content of the tackifier in the polymer layer is less than 1% by mass with respect to the total amount of SIBS and tackifier, the vulcanized adhesive strength with the carcass and the rubber layer tends to be insufficient, and 50% by mass. If it exceeds 1, the tackiness becomes too high, the workability and productivity are lowered, and the gas barrier property tends to be lowered. By blending an appropriate amount of the tackifier, the effect of reducing the viscosity as a blend is obtained, leading to an improvement in film extrusion (workability / productivity).

  Moreover, although the preferable range of content of SIBS and tackifier in a polymer layer was demonstrated as mentioned above, these content prescribes | regulates either one content with respect to the total amount of SIBS and tackifier. By doing so, the other content is naturally determined.

  In the present specification, “tackifier” refers to an additive for enhancing the tackiness of a general thermoplastic elastomer composition.

The tackifier desirably has a weight average molecular weight Mw of 1 × 10 ² to 1 × 10 ⁶ and a softening point in the range of 50 to 150 ° C. If the weight average molecular weight is less than 1 × 10 ² , the viscosity tends to be low, and the formability of the sheet tends to be disadvantageous. On the other hand, if it exceeds 1 × 10 ⁶ , tackiness to the polymer layer is not sufficient Tend. When the tackifier is an isobutylene-based low molecular weight substance to be described later, the number average molecular weight is preferably 200 or more, and more preferably 1500 or more. Further, the number average molecular weight of the isobutylene-based low molecular weight body is preferably 3000 or less, and more preferably 2500 or less. A number average molecular weight of 1500 to 2500, which has a higher molecular weight than general resins such as terpene resins and terpene phenol resins, tends to have better performance. Furthermore, when the tackifier is an epoxidized styrene-butadiene-styrene triblock copolymer (hereinafter also referred to as epoxidized SBS), the weight average molecular weight is 1 from the viewpoint of rubber elasticity and moldability. It is preferable that it is * 10 < ⁴ > -4 * 10 < ⁵ >. The weight average molecular weight by the 1 × 10 ⁴ or more, preferably for dimensions too soft there is no possibility that unstable, 4 × 10 ⁵ in the following cases preferable because there is no fear that can not be thin extruded too hard. The weight average molecular weight Mw is a value obtained by styrene conversion by gel permeation chromatography measurement, and the number average molecular weight Mn is a value obtained by a vapor pressure measurement method.

  Specific examples of the tackifier include C9 petroleum resin, C5 petroleum resin, terpene resin, aromatic modified terpene resin, terpene phenol resin, coumarone resin, coumarone indene oil, rosin ester, hydrogenated rosin ester, alkylphenol resin, DCPD. , Isobutylene-based low molecular weight substances, epoxidized SBS, and the like.

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

  “C5 petroleum resin” is obtained by thermally decomposing naphtha to obtain useful compounds such as ethylene, propylene and butadiene, but mixing the remaining C4 to C5 fractions (mainly C5 fractions) from which they have been removed. It is an aliphatic petroleum resin obtained by polymerization in the state. As trade names, Highlets G100 (Mitsui Petrochemical Co., Ltd., softening point 100 ° C.), Marcaretz T100AS (Maruzen Petroleum Co., Ltd., softening point 100 ° C.), and Escorez 1102 (Tonex Corp., softening point) 110 ° C.).

  As "terpene resin", YS Resin PX800N, PX1000, PX1150, PX1250, PXN1150N, Clearon P85, P105, P115, P125, P135, P150, M105, M115, K100 (all manufactured by Yasuhara Chemical Co., Ltd.) Softening point 75-160 ° C).

  “Aromatically modified terpene resins” include YS resin TO85, TO105, TO115, and TO125 (all manufactured by Yasuhara Chemical Co., Ltd., softening point: 75 to 165 ° C.) as trade names.

  As "terpene phenol resin", as a trade name, TAMANOL 803L, 901 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 120 ° C to 160 ° C), YS polystar U115, U130, T80, T100, T115, T145, T160 (Both manufactured by Yasuhara Chemical Co., Ltd., softening point 75-165 ° C.).

  As “coumarone resin”, there is coumarone resin (manufactured by Kobe Oil Chemical Co., Ltd.) having a softening point of 90 ° C.

  “Cumaron Inden Oil” has a trade name of 15E (manufactured by Kobe Oil Chemical Co., Ltd., pour point 15 ° C.).

  As “rosin ester”, ester gum AAL, A, AAV, 105, AT, H, HP, HD (all manufactured by Arakawa Chemical Industries, softening point 68 ° C. to 110 ° C.), and Harrier Star TF, S, C, DS70L, DS90, and DS130 (all manufactured by Harima Chemical Co., Ltd., softening point 68 ° C to 138 ° C) are available.

  “Hydrogenated rosin ester” includes, as trade names, superesters A75, A100, A115, and A125 (all manufactured by Arakawa Chemical Industries, Ltd., softening point: 70 ° C. to 130 ° C.).

  As the “alkylphenol resin”, as a trade name, there is TAMANOL 510 (manufactured by Arakawa Chemical Industries, Ltd., softening point: 75 ° C. to 95 ° C.).

  As “DCPD”, there is a trade name “Escollets 5300” (manufactured by Tonex Co., Ltd., softening point 105 ° C.).

  “Isobutylene-based low molecular weight substance” is a substance for enhancing the tackiness of a thermoplastic elastomer composition, specifically, a low molecular weight reaction product obtained by the reaction of maleic anhydride, an amine compound and isobutylene. It is a thing. Since it is composed of isobutylene, which is the main component of SIBS, which is the main component of the polymer layer used for the inner liner layer, the components that make up the polymer layer and the components of the tackifier are the same, increasing the adhesion In addition to the effects, other tire performances such as air permeation resistance, low fuel consumption, and tire durability can also be obtained.

  Among isobutylene-based low molecular weight compounds, a specific method, for example, a method described in JP-A-61-207399, that is, an amine compound is reacted with maleic anhydride, and then isobutylene is reacted with the resulting product. What is obtained by the method of making it react is preferable from compatibility with a styrene-isobutylene-styrene triblock copolymer being the best, and since dispersibility is also good, in addition to the adhesion enhancing effect, it can also anticipate low fuel consumption. Moreover, since the molecular weight can be easily controlled, an improvement in productivity can be expected. Such an isobutylene-based low molecular weight substance includes a compound in which an isobutylene oligomer and one molecule of maleic anhydride amine derivative are added from an addition compound obtained by reacting one molecule of a maleic anhydride amine derivative and isobutylene, Various compounds such as random copolymerization, block copolymerization, graft copolymerization or alternating copolymerization of isobutylene units and maleic anhydride amine derivative units are included. In any case, the molecular weight is generally about 200 to 3000. Is.

  Various amine compounds can be used for the reaction between maleic anhydride and the amine compound, and are not particularly limited. Specifically, aliphatic amines such as propylamine, isopropylamine, butylamine, diethylamine, dipropylamine, allylamine and diallylamine; alicyclic amines such as cyclopropylamine and cyclobutylamine; aromatics such as aniline and p-aminotoluene Group amines and the like.

  The ratio of maleic anhydride and amine compound in the reaction of maleic anhydride and amine compound is not particularly limited, but is usually 0.01 to 2.0 amine compound per mole of maleic anhydride. Mole is preferable, and 0.05 to 1.5 mol is more preferable. If the proportion of the amine compound is too small, the molecular weight of the finally obtained isobutylene product is undesirably high, and conversely, if the proportion of the amine compound is too large, it remains unreacted.

  The reaction between maleic anhydride and the amine compound is not particularly limited, but is preferably 0 to 70 ° C., more preferably 10 to 50 ° C., preferably 0.5 to 10 hours, more preferably Is performed for 1 to 5 hours.

  The resulting maleic anhydride amine derivative gives an isobutylene-based low molecular weight product by reaction with isobutylene. For the reaction between this maleic anhydride amine derivative and isobutylene, one molecule of isobutylene per one maleic anhydride amine derivative is used. As well as a reaction of adding two or more molecules of isobutylene, and a reaction of copolymerizing a maleic anhydride amine derivative and isobutylene.

  The ratio of maleic anhydride amine derivative to isobutylene in the reaction of maleic anhydride amine derivative with isobutylene is not particularly limited, but usually, isobutylene 0.1 to 0.1 mol per mole of maleic anhydride amine derivative. 5 mol is preferable and 0.5-3 mol is more preferable.

  The reaction between the maleic anhydride amine derivative and isobutylene is not particularly limited, but is preferably 30 to 200 ° C, more preferably 45 to 150 ° C, preferably 0.1 to 3 MPa, more preferably The reaction is carried out at a reaction pressure of 0.1 to 2 MPa, preferably 0.5 to 20 hours, more preferably 1 to 10 hours.

  “Epoxidized SBS” is a thermoplastic elastomer in which a hard segment is a polystyrene block, a soft segment is a butadiene block, and an unsaturated double bond portion contained in the butadiene block is epoxidized. Epoxidized SBS has a soft segment composed of a butadiene block, and thus is easily vulcanized and bonded to a rubber component. Moreover, since epoxidized SBS has a styrene block, it is excellent in melt adhesiveness with SIBS similarly having a styrene block. Furthermore, since it has excellent air permeation resistance, the inner liner is maintained while maintaining air permeation resistance by mixing epoxidized SBS with SIBS as a tackifier and applying it as a polymer layer to the inner liner layer. It is possible to effectively impart tackiness and adhesiveness to the layer. For example, it is disposed adjacently between a rubber layer for forming a carcass or insulation and a protective rubber layer on the inner radial direction of the inner liner. When sulfurated, the adhesion between the polymer layer and the rubber layers adjacent to both sides can be improved, and as a result, an effect of improving tire durability can be obtained.

  The content of styrene units in the epoxidized SBS is preferably 10% by mass or more and 30% by mass or less from the viewpoints of tackiness, adhesiveness, and rubber elasticity. The epoxidized SBS preferably has a molar ratio of butadiene units to styrene units (butadiene units / styrene units) of 90/10 to 70/30. In the epoxidized SBS, the degree of polymerization of each block is preferably about 500 to 5,000 for a butadiene block and about 50 to 1,500 for a styrene block from the viewpoint of rubber elasticity and handling.

  The epoxy equivalent of the epoxidized SBS is preferably 50 or more and 1,000 or less from the viewpoint of adhesiveness.

  As the tackifier, C9 petroleum resin fully hydrogenated petroleum resin, terpene resin, isobutylene low molecular weight substance, and epoxidized SBS have good compatibility with SIBS, and adhesion is not reduced. It is preferable because the properties can be improved. Furthermore, these tackifiers also have an effect of lowering the viscosity and can be advantageously used for film extrusion molding.

  The thickness of the polymer layer is 0.05 to 0.5 mm. If the thickness of the polymer layer is less than 0.05 mm, the polymer layer may be broken by pressing pressure when the raw tire is vulcanized, and an air leak phenomenon may occur in the obtained tire. On the other hand, if the thickness of the polymer layer exceeds 0.5 mm, the tire weight increases and the fuel efficiency tends to decrease.

  In addition to the above SIBS and tackifiers, the polymer layer includes reinforcing agents, clay minerals, pigments, vulcanizing agents, vulcanization accelerators, various oils, anti-aging agents, softeners, plasticizers, coupling agents, etc. These additives can also be contained, and the content of these additives can also be a general amount in this technical field.

  Examples of the reinforcing agent include carbon black and silica, and carbon black is preferable from the viewpoint of maintaining sufficient fracture characteristics. In the case of containing a reinforcing agent, the content of SIBS and tackifier in a total of 100 parts by mass is preferably 20 parts by mass or more, and more preferably 25 parts by mass or more. When the amount is less than 20 parts by mass, sufficient reinforcing properties tend not to be obtained. Moreover, 80 mass parts or less are preferable, as for content with respect to a total of 100 mass parts of SIBS and tackifier of a reinforcing agent, 75 mass parts or less are more preferable, and 70 mass parts or less are more preferable. When it exceeds 80 mass parts, there exists a tendency for workability to deteriorate, a tendency for low fuel consumption to fall, and a tendency for abrasion resistance to fall.

  Although it does not specifically limit as a clay mineral, A layered clay mineral, an organically-treated clay mineral, etc. can be used. 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. In montmorillonite, a portion of Al, which is the central atom of the alumina octahedron layer in the crystal structure, is replaced with Mg, resulting in insufficient positive charge, and each crystal layer itself is negatively charged. By sandwiching cations such as ⁺ , K ⁺ , Ca ²⁺ and Mg ²⁺ , neutralization of charge shortage is achieved 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, subine Phyllosilicates such as smectite clays such as foldite, vermiculite, mica minerals such as illite and illite / smectite mixtures (lectretite, talosobite, ladykite and mixtures of the above clay compounds with illite) or attapulgite and sepiolite hydro Examples thereof include talcite-based layered compounds. 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 and the like, 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 Examples thereof include aliphatic amines such as amines.

  Preferable amides include hexylamide, heptylamide, octylamide, nonylamide, lauramide, myristamide, palmitamide, stearamide, 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, dimethylbenzyl 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.

  When the clay mineral is contained, the content of SIBS and the tackifier in a total of 100 parts by mass is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more. When the amount is less than 0.1 parts by mass, the air permeation resistance tends to decrease. Moreover, 50 mass parts or less are preferable and, as for content with respect to 100 mass parts in total of SIBS of a clay mineral, and a tackifier, 30 mass parts or less are more preferable. When it exceeds 50 parts by mass, the hardness tends to be too large.

  The polymer layer is mixed with SIBS and a tackifier according to a prescribed formulation, and other additives as necessary, pelletized with a twin-screw extruder, and then used with a T-die extruder or an inflation co-extruder. Can be produced.

  Further, in the present invention, the inner liner layer 8 is preferably composed only of the polymer layer containing the SIBS and tackifier, but is obtained by laminating an additional layer in contact with the rubber layer 9 in addition to the polymer layer. It is also possible to use a laminated body.

  When the inner liner layer satisfies the condition (a) among the conditions (a) and (b) in the pneumatic tire of the present invention, the inner liner layer 8 is different from the first region and the first region. And a second region that is thicker than the first region. The thickness referred to here is the thickness in the cross section in the tire meridian direction. When satisfying the pneumatic tire (b) of the present invention, the inner liner layer 8 may satisfy (a) or may have a uniform thickness over the entire region.

  In the condition (a), the second region having a thickness larger than that of the first region is likely to have a relatively low air permeation resistance with time, and the surrounding tire members are deteriorated due to oxidation deterioration. In contrast to this, the first region is a region where there is no such concern and the air permeation resistance is good over time. By increasing the thickness in the second region as described above, the oxidative deterioration of the tire member can be effectively suppressed, and the durability and air permeation resistance of the tire can be improved.

  Although the tire weight increases as the thickness of the second region is increased, according to the present invention, since the inner liner layer including the predetermined polymer layer is used, it is made of another thermoplastic resin and has the same thickness profile. It is possible to reduce the tire weight (and thus improve the rolling resistance) compared with the case where the conventional inner liner layer having the conventional inner liner layer is used, and further, the conventional inner liner made of another thermoplastic resin and not provided with a thickening region. The tire weight can be reduced as compared with the case where the liner layer is used. As described above, according to the present invention, the tire weight is increased by increasing the thickness of the inner liner layer. However, the disadvantage of the increase in weight is overcome, and the rolling resistance is improved while improving the durability and air permeation resistance. It is possible to improve the property. This also applies to a pneumatic tire that satisfies the condition (b).

  Referring to FIG. 1, more specifically, the first region can be a region R <b> 1 corresponding to the tread portion 1 in the inner liner layer 8. The region corresponding to the tread portion 1 refers to a region on the inner side in the tire width direction from a position corresponding to the outermost main groove 11 of the tread portion 1. In this region, since the belt layer 7 and the tread portion 1 are laminated in addition to the carcass layer 6, the region has good air permeation resistance.

  The second region having a thickness larger than that of the first region is at least a part of the region other than the first region, and more specifically, corresponds to the shoulder portion 2 to the buttress portion 3 with reference to FIG. One or more of the region R2, the region R3 corresponding to the sidewall portion 4, and the region R4 corresponding to the bead portion 5 can be used. You may make it enlarge the thickness of a part of these area | regions. Since the sidewall portion 4 is thin, the air permeation resistance is likely to decrease. Further, the durability of the region extending from the shoulder portion 2 to the buttress portion 3 and the bead portion 5 is likely to decrease due to oxidative deterioration of the surrounding tire members when the air permeation resistance decreases.

  The region R2 corresponding to the buttress portion 3 from the shoulder portion 2 is a region located between the region R1 corresponding to the tread portion 1 and the region R3 corresponding to the sidewall portion 4, and the thickness of at least a part of the region R2. Is larger than the region R1, for example, when a perpendicular is drawn from the end 71 of the belt layer 7 having the maximum width to the inner liner layer 8, the section in the tire meridian direction is centered on the intersection of the perpendicular and the inner liner layer 8. The thickness within the range of 5 to 10% of the inner periphery (the length along the tire inner peripheral surface from one bead toe to the other bead toe in the tire meridian cross section) is made larger than the region R1 It is preferable. Thereby, the tire durability can be improved without excessively increasing the tire weight.

  The aspect in which the thickness of at least a part of the region R2 is larger than that of the region R1 can be used particularly preferably for a heavy duty pneumatic tire.

  The region R3 corresponding to the sidewall portion 4 is a region located between the shoulder portion 2 to the region R2 corresponding to the buttress portion 3 and the region R4 corresponding to the bead portion 5, and the thickness of at least a part of the region R3. Is made larger than the region R1, for example, when a perpendicular is drawn from the point B of the maximum width of the carcass line to the inner liner layer 8, the inner periphery of the inner peripheral 3 is centered on the intersection of the perpendicular and the inner liner layer 8. It is preferable to make the thickness within the range of 8% larger than the region R1. Thereby, the tire durability can be improved without excessively increasing the tire weight.

  The aspect in which the thickness of at least a part of the region R3 is made larger than that of the region R1 can be suitably applied particularly to a passenger car pneumatic tire.

  The region R4 corresponding to the bead portion 5 is a region following the region R3 corresponding to the sidewall portion 4, and when the thickness of at least a part of the region R4 is larger than the region R1, for example, from the end 61 of the carcass layer 6 When a perpendicular is drawn to the inner liner layer 8, it is preferable to increase the thickness within a range of 3 to 10% of the inner peripheral with the intersection of the perpendicular and the inner liner layer 8 as the center. Thereby, the tire durability can be improved without excessively increasing the tire weight. Making the thickness of the region R4 larger than the region R1 is particularly effective in preventing the oxidative deterioration of the chafer 52, which is liable to cause oxidative deterioration due to a decrease in air permeation resistance and cause problems such as chafer separation. The durability of can be improved.

  The aspect in which the thickness of at least a part of the region R4 is larger than that of the region R1 can be suitably applied particularly to a heavy duty pneumatic tire.

  As described above, the thickness of the inner liner layer 8 is 0.05 to 0.5 mm when the inner liner layer is made of the above-described polymer layer containing SIBS, and the thicknesses of the first region and the second region are respectively The ratio T2 / T1 of the thickness T2 of the second region to the thickness T1 of the first region is preferably 1.05 to 3, more preferably 1.1 to 2, as long as it is within the range. Preferably, it is 1.1-1.7. If it is in this range, the above-mentioned effect by making the thickness of the second region larger than the region R1 can be sufficiently obtained.

  The method for making the thickness of the second region larger than that of the region R1 is not particularly limited, and can be achieved by forming the corresponding part thicker than the region R1.

  The rubber layer 9 is a layer disposed between the pair of left and right bead portions 5 on the inner side in the tire radial direction of the inner liner layer 8 and plays a role of protecting the extremely thin inner liner layer 8. By providing the rubber layer 9, it is possible to effectively cause damage to the inner liner layer 8 due to contact with tools during rim assembling work, or damage when buffing the tire inner surface in puncture repair or the like. Can be prevented. Thereby, the fall of durability of a tire and air permeability resistance can be suppressed effectively.

  The rubber constituting the rubber layer 9 preferably has good air permeation resistance. Specific examples thereof include natural rubber, epoxidized natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber and nitrile rubber. And diene rubbers such as butyl rubber and halogenated butyl rubber. Of these, butyl rubber having better air permeation resistance is preferred.

  In addition to the rubber component, the rubber layer is blended with a general rubber composition such as a reinforcing agent, a vulcanizing agent, a vulcanization accelerator, various oils, an anti-aging agent, a softening agent, a plasticizer, and a coupling agent. The content of these additives can also be set to a general amount in this technical field.

  The thickness of the rubber layer 9 is preferably 0.2 to 2 mm and more preferably 0.5 to 1.5 mm in order to effectively prevent damage to the inner liner layer 8.

  When the pneumatic tire of the present invention satisfies (b) among the above-described thickness conditions (a) and (b), the rubber layer 9 is a region different from the third region and the third region. And a fourth region having a thickness larger than that of the third region. The thickness referred to here is the thickness in the cross section in the tire meridian direction. When the pneumatic tire of the present invention satisfies (a), the rubber layer 9 may satisfy (b) or may have a uniform thickness over the entire region. More preferably, the inner liner layer 8 satisfies (a) and the rubber layer 9 satisfies (b).

  In the condition (b), the fourth region whose thickness is larger than that of the third region is a region where the inner liner layer 8 is easily damaged in the above-described scene, specifically, the tread portion 1 in the rubber layer 9. Corresponding region R1. The region corresponding to the tread portion 1 refers to a region on the inner side in the tire width direction from a position corresponding to the outermost main groove 11 of the tread portion 1. The third region can be any region other than the fourth region.

  The thicknesses of the third region and the fourth region of the rubber layer 9 are not particularly limited as long as they are within the range of 0.2 to 2 mm, respectively, but the ratio T4 / the thickness T4 of the fourth region to the thickness T3 of the third region T3 is preferably 1.05 to 20, more preferably 1.1 to 15, further preferably 1.2 to 10, and particularly preferably 1.2 to 5. The thickness T4 of the fourth region is preferably 0.5 to 2 mm, and more preferably 0.8 to 1.5 mm.

  Further, when satisfying the above (b) which is an embodiment of the present invention, by partially thickening the protective rubber layer 9, it is possible to prevent the inner liner from being damaged due to puncture repair or the like. It is possible to maintain barrier properties, improve adhesion with adjacent carcass plies, improve tire durability, and bead durability. By partially thickening the protective rubber layer 9, the tire weight increases, but by using SIBS for the inner liner layer, the thickness can be reduced, the increase in weight is suppressed, and the deterioration of rolling resistance is suppressed. .

  The rubber layer 9 can be manufactured by a conventionally known method such as extrusion molding or calendar molding. The method for increasing the thickness of the fourth region is not particularly limited, and 1) a method of forming a thick portion corresponding to the fourth region, 2) a method of laminating a plurality of rubber layers in the portion corresponding to the fourth region, and the like. Can be adopted.

  The carcass layer 6 is a rubber member in which cords are arranged and embedded. The cord is made of organic fibers such as polyester, nylon, and aramid, and steel. The rubber constituting the carcass layer 6 is not particularly limited, and may be natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, or the like. The carcass layer 6 can contain a usual additive, for example, a filler such as carbon black or silica.

  The pneumatic tire of the present invention uses the polymer layer described above as an inner liner layer, and constructs an unvulcanized tire according to a general manufacturing method, except that a rubber layer is disposed on the inner side in the tire radial direction, This can be produced by vulcanization molding. Specifically, after the polymer mixture according to a predetermined formulation is pelletized by, for example, a twin screw extruder, it is formed into a sheet using a T-die extruder (extrusion temperature is, for example, 130 ° C. to 200 ° C.). Extruded into a film) and bonded together with a rubber layer and other tire members on a tire molding machine to form an unvulcanized tire. A pneumatic tire can be manufactured by heating and pressurizing the uncrosslinked tire in a vulcanizer.

  In the pneumatic tire, it is preferable that the thickness of the inner liner layer measured at the maximum tire width position filled with the specified internal pressure is in the range of 0.05 to 0.5 mm. When the thickness of the inner liner layer is thicker than 0.05 mm, the effect of suppressing the decrease in air pressure is good, and when it is less than 0.5 mm, the effect of improving the fuel consumption by reducing the weight of the tire is good.

  The pneumatic tire in the embodiment of the present invention can be applied to various pneumatic tires such as for passenger cars, trucks and buses, heavy machinery and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited only to an Example.

Hereinafter, various materials used in Examples and Comparative Examples are shown together.
SIBS: SIBSTAR (registered trademark) 102 manufactured by Kaneka Corporation (Shore A hardness 25, styrene component content: 25 mass%, weight average molecular weight Mw by GPC measurement (standard polystyrene conversion): 100,000)
Tackifier A: C9 petroleum resin, Alcon P140 manufactured by Arakawa Chemical Industries, Ltd. (softening point 140 ° C., weight average molecular weight Mw: 900)
Tackifier B: terpene resin, YS resin PX1250 manufactured by Yasuhara Chemical Co., Ltd. (softening point 125 ° C., weight average molecular weight Mw: 700)
Tackifier C: isobutylene low molecular weight product produced in Production Example 1 below (number average molecular weight by vapor pressure measurement method: 240)
Tackifier D: isobutylene-based low molecular weight product produced in Production Example 2 below (number average molecular weight by vapor pressure measurement method: 2200)
Tackifier E: Epoxidized SBS, Epofriend A1020 manufactured by Daicel Chemical Industries, Ltd. (epoxidized styrene-butadiene-styrene triblock copolymer, weight average molecular weight Mw: 100,000, epoxy equivalent 500)
Reinforcing agent: Seast V manufactured by Tokai Carbon Co., Ltd. (N660, N ₂ SA: 27 m ² / g)
Clay mineral: “BENTONE 34” manufactured by Rheox (Organized clay mineral (layered clay mineral: hectorite clay mineral, organic compound: dimethyl distearyl ammonium salt, cation exchange amount of organic compound: 100 meg / 100 g))
Chlorobutyl rubber: “Exon Chlorobutyl 1068” manufactured by ExxonMobil Co., Ltd.

Production Example 1: Production of isobutylene-based low molecular weight substance In a four-necked flask, a solution of 60 g of maleic anhydride dissolved in 200 ml of acetonitrile was sampled, and 44.8 g of diethylamine was gradually added dropwise and reacted at 25 ° C. for 5 hours. A maleic anhydride diethylamine derivative was obtained.

  Subsequently, the obtained diethylamine maleate derivative was put in a 1 liter autoclave, 0.6 g of benzoyl peroxide and 260 ml of acetonitrile were further added, and the mixture was cooled with a dry ice-acetone solution to perform deaeration. Next, 37 g of isobutylene was supplied, the temperature was raised to 110 ° C., and 0.9 rpm, 400 r. p. m. The reaction was carried out at a rotational speed of 2 hours.

  After completion of the reaction, the reaction solution was distilled with an evaporator at 170 ° C. and 266.6 Pa for 5 hours to obtain 108 g of an isobutylene-based low molecular weight product. The number average molecular weight of the obtained isobutylene-based low molecular weight product was 240.

Production Example 2: Production of isobutylene-based low molecular weight substance After reacting 470 g of aniline with 60 g of maleic anhydride gradually dissolved at 25 ° C., 0.6 g of benzoyl peroxide was added and charged into a 1 liter autoclave. It is. Subsequently, it cooled with the dry ice-acetone solution and deaerated. Further, 37 g of isobutylene was supplied and the temperature was raised to 110 ° C., and then the reaction solution was distilled with an evaporator at 170 ° C. and 266.6 Pa for 5 hours to obtain 91 g of a low molecular weight product. The obtained low molecular weight product had an acid value of 182 mgKOH / g and a number average molecular weight of 2200.

Example 1
<Preparation of inner liner layer (unvulcanized)>
30 parts by mass of a reinforcing agent and 15 parts by mass of a clay mineral are kneaded with 99 parts by mass of SIBS and 1 part by mass of a tackifier A, and a twin screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.). To obtain a polymer composition for the inner liner layer. Thereafter, the polymer composition for the inner liner layer is extruded using a T-die extruder (screw diameter: φ80 mm, L / D: 50, die lip width: 500 mm, cylinder temperature: 220 ° C., film gauge: 0.3 mm). And a polymer sheet (unvulcanized inner liner layer) was produced. The thickness of the polymer sheet was uniform throughout, and the thickness (thickness in the cross section in the tire meridian direction in a state filled with the specified internal pressure after vulcanization) was set to 0.05 mm.

<Production of rubber layer (unvulcanized)>
Using a T-die extruder, chlorobutyl rubber (“Exon Chlorobutyl 1068” manufactured by ExxonMobil Co., Ltd.) as a rubber component is kneaded using other general compounding agents, and rubber for rubber layers A composition was obtained. At that time, a profile is attached to the extrusion port of the T-die extruder, and the thickness of the region corresponding to the tread portion (thickness in the tire meridian cross section after vulcanization and filled with the specified internal pressure) is 1.0 mm. All the thicknesses of the region were adjusted to 0.5 mm.

<Manufacture of pneumatic tires>
The polymer sheet is applied to the inner liner layer, and the rubber layer is disposed on the inner side in the tire radial direction to produce a green tire. Next, in the vulcanization process, press molding is performed at 170 ° C. for 20 minutes, and FIG. A 195 / 65R15 size pneumatic tire having the basic structure shown in FIG. In addition, about structures other than the above-mentioned inner liner layer and rubber layer, the same material was used in the following comparative examples and examples using materials generally used in the manufacture of tires.

Comparative Examples 1, 4 and 7-10 and Examples 6, 7, 12, 17, 18, 23, 28, 33, 38, 43 and 48
A pneumatic tire was manufactured in the same manner as in Example 1 except that a polymer sheet for the inner liner layer was prepared according to the formulation shown in Tables 1 and 3 to 5.

Comparative Examples 2, 3, 5 and 6 and Examples 2-5, 8-11, 13-16, 19-22, 24-27, 29-32, 34-37, 39-42, 44-47 and 49 ~ 52
In accordance with the formulation shown in Tables 1 to 5, a polymer sheet for the inner liner layer is prepared. As shown in Table 1, the region corresponding to the buttress portion from the shoulder portion, the region corresponding to the sidewall portion, and the bead portion. A pneumatic tire was manufactured in the same manner as in Example 1 except that a polymer sheet in which the thickness of the corresponding region (thickness in the tire meridian direction cross section after vulcanization and filled with the specified internal pressure) was used was used. The thickness was adjusted by creating a polymer sheet for an inner liner by attaching a profile to the extrusion port of a T-die extruder.

  The following tire weight measurements and evaluation tests were performed on the pneumatic tires and inner liner layers produced in the examples and comparative examples. Tables 1 and 2 show the test results expressed as indices.

  In the table, the region R2 corresponding to the buttress portion from the shoulder portion is a tire meridian direction centered on the intersection of the perpendicular and the inner liner layer 8 when a perpendicular is drawn from the end 71 of the belt layer 7 to the inner liner layer 8. The length corresponding to 5 to 10% of the length of the inner peripheral along the inside of the cross section, and the region R3 corresponding to the sidewall portion is perpendicular to the inner liner layer 8 from the point B at the maximum width of the carcass line. Is a length corresponding to 3 to 8% of the inner peripheral length with the intersection of the perpendicular and the inner liner layer 8 as the center, and the region R4 corresponding to the bead portion of the carcass layer 6 When a perpendicular is drawn from the end 61 to the inner liner layer 8, the length of the inner periphery is 3 to 1 around the intersection of the perpendicular and the inner liner layer 8. It was a length corresponding to%.

<Measurement of tire weight>
The tire weight was measured, and the tire weight index was calculated according to the following formula (1). The reference example is Comparative Example 1. The larger the tire weight index, the smaller the tire weight and the higher the achievement of weight reduction.
Tire weight index = (tire weight of reference example) / (tire weight of each example and comparative example) × 100 (1)

<Evaluation of air permeation resistance>
A pneumatic tire was mounted on a rim (22.5 × 7.50), and the internal pressure was measured every 4 days while being left to stand for 3 months under an initial pressure of 900 kPa, a room temperature of 21 ° C., and no load. Based on the following formula (2), the regression coefficient α was calculated as the initial pressure P0 (kPa), the measured pressure Pt (kPa), and the elapsed time t (day). From the obtained regression coefficient α, the pressure decrease rate β (% / month) per month was calculated on the basis of the following formula (3) as t = 30 (day). The obtained β value was used as an index with the value of Comparative Example 1 as 100, and the air permeation prevention performance is shown in Tables 1 and 2. The larger this index, the better the air permeation prevention performance.
Pt / P0 = exp (−αt) (2)
β = (1-exp (−αt)) × 100 (3)

<Evaluation of tire durability>
The obtained tire is mounted on a rim (22.5 × 7.50), applied to an indoor drum tester (drum diameter 1707 mm) in accordance with JIS D4230, filled with air adjusted to an oxygen concentration of 60%, and the air pressure is set to JATMA. The running distance until tire failure occurred under the condition of a specified air pressure of 900 kPa, 150% of JATMA specified load capacity, and speed of 81 km / h was measured. The obtained travel distance was used as an index with the value of Comparative Example 1 as 100. It shows that tire durability is excellent, so that this parameter | index is large.

<Evaluation of vulcanized adhesive strength>
A peel test was conducted according to JIS K 6256 “Vulcanized Rubber and Thermoplastic Rubber—How to Determine Adhesiveness”. First, the polymer sheet for the inner liner having a thickness of 0.3 mm, the rubber sheet having a thickness of 2 mm (formulation: NR / BR / SBR = 40/30/30), and the reinforced canvas fabric are stacked in the order described above at 170 ° C. The test piece for peeling was produced by pressurizing and heating for 12 minutes under these conditions. Using the obtained test piece, a peel test was performed to measure the adhesive force between the polymer sheet for the inner liner and the rubber sheet. The size of the test piece was 25 mm, and the test was performed at room temperature of 23 ° C. The peel strength index was calculated from the obtained numerical value by the following formula (4) with the value of Comparative Example 1 being 100. It shows that it is excellent in adhesiveness, so that a numerical value is large.
(Vulcanization adhesion index)
= (Adhesive strength of each formulation) / (Adhesive strength of Comparative Example 1) × 100 (4)

<Evaluation of rolling resistance>
The rolling resistance of the tire was evaluated according to the following procedure. Using a viscoelastic spectrometer VES (Iwamoto Seisakusho Co., Ltd.), tan δ of each tire was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, and a dynamic strain of 2%. And according to the following formula (5) which sets the value of the comparative example 1 to 100, the rolling resistance index was calculated. The larger the index, the better the rolling resistance. The performance target value is 93 or more.
Rolling resistance index = tan δ of Comparative Example 1 / tan δ of each formulation × 100 (5)

DESCRIPTION OF SYMBOLS 1 Tread part 11 Main groove 2 Shoulder part 3 Buttress part 4 Side wall part 5 Bead part 51 Bead core 52 Chafer 6 Carcass layer 61 End of carcass layer 7 Belt layer 71 End of belt layer having the maximum width 8 Inner liner layer 9 Rubber Layer T Pneumatic tire A Crown center position B Maximum width of carcass line R1 Area corresponding to tread part R2 Area corresponding from shoulder part to buttress part R3 Area corresponding to side wall part R4 Area corresponding to bead part

Claims (7)

Carcass layer,
A pneumatic tire comprising an inner liner layer disposed inside the tire of the carcass layer, and a rubber layer disposed inside the tire of the inner liner layer,
The inner liner layer is a polymer layer having a thickness of 0.05 to 0.5 mm containing a styrene-isobutylene-styrene triblock copolymer and a tackifier disposed so as to be in contact with the carcass layer. Polymer layer containing 99-50% by mass of styrene-isobutylene-styrene triblock copolymer and 1-50% by mass of tackifier based on the total amount of isobutylene-styrene triblock copolymer and tackifier Including
Next (a) and (b):
(A) the inner liner layer includes a first region and a second region that is different from the first region and is thicker than the first region; and (b) the rubber layer includes A pneumatic tire that satisfies at least one of the third region and a fourth region that is different from the third region and has a thickness greater than that of the third region. The first region is a region corresponding to a tread portion in the inner liner layer, and the second region is at least a part of the inner liner layer other than the first region. Pneumatic tire. The pneumatic region according to claim 1 or 2, wherein the fourth region is a region corresponding to a tread portion in the rubber layer, and the third region is all regions other than the fourth region in the rubber layer. tire. The tackifier is a group consisting of C9 petroleum resin, C5 petroleum resin, terpene resin, aromatic modified terpene resin, terpene phenol resin, coumarone resin, coumarone indene oil, rosin ester, hydrogenated rosin ester, alkylphenol resin and DCPD. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is at least one selected from the above. The pneumatic tire according to any one of claims 1 to 3, wherein the tackifier is an isobutylene-based low molecular weight substance. The pneumatic tire according to any one of claims 1 to 3, wherein the tackifier is an epoxidized styrene-butadiene-styrene triblock copolymer. The styrene-isobutylene-styrene triblock copolymer has a styrene component content of 10 to 40% by mass and a weight average molecular weight of 50,000 to 400,000. The described pneumatic tire.

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