JP6154984B2 - Unvulcanized tires and pneumatic tires - Google Patents

Description

  The present invention relates to an unvulcanized tire having an inner liner that can flexibly cope with a tire size having a high inner expansion rate while effectively preventing joint cracking that may occur at the time of molding or after molding, and pneumatic using the same. Regarding tires.

  Conventionally, a rubber composition mainly composed of butyl rubber, halogenated butyl rubber or the like is used for an inner liner disposed as a gas barrier layer on the inner surface of the tire in order to maintain the internal pressure of the tire. However, these rubber compositions using butyl rubber as the main raw material have low gas barrier properties, and therefore when the rubber composition is used for an inner liner, the thickness of the inner liner has to be about 1 mm. Therefore, the weight of the inner liner in the tire is about 5%, which is an obstacle to improving the fuel efficiency of automobiles, agricultural vehicles, construction vehicles, etc. by reducing the weight of the tires.

  On the other hand, an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is known to have excellent gas barrier properties. Since the EVOH has an air permeation amount of 1/100 or less of the butyl rubber, when used for the inner liner, the internal pressure retention of the tire can be greatly improved even with a thickness of 100 μm or less. It is possible to reduce the weight of the tire.

  Here, there are many resins having a lower air permeability than the butyl rubber, but if the air permeability is about one-tenth of that of the butyl rubber, the effect of improving the internal pressure retention is required unless the thickness exceeds 100 μm. Is small. On the other hand, when the thickness exceeds 100 μm, the effect of reducing the weight of the tire is small, and the inner liner is broken or cracked in the inner liner due to deformation at the time of bending of the tire, so that the gas barrier property is maintained. It becomes difficult.

  As means for solving this, Patent Document 1 discloses a tire in which a terminal rubber portion is disposed on a side facing the inner liner at a circumferential joint portion of a carcass ply, and prevents inner cracks. Thin gauge has been realized. Patent Document 2 discloses an inner liner in which a gas barrier layer is formed by applying an unmodified or modified EVOH solution, and the uniformity of the tire is deteriorated by eliminating the joint portion between the gas barrier layers. While improving, it is trying to achieve both weight reduction and gas barrier properties. Further, Patent Documents 3 to 4 also disclose tires provided with an inner liner layer formed on a cylindrical film.

JP 2006-224853 A JP 2007-112000 A Japanese Patent No. 3159886 International Publication No. 2004/110735

  However, even when the inner liner as described above is employed, when unvulcanized tires are expanded at the time of molding, the robustness tends to be low for tire sizes with a high inner expansion rate, and the existing In some cases, it is not possible to effectively utilize these facilities, and there is still room for improvement.

  Therefore, the present invention effectively eliminates joint cracks that may occur during or after molding so that it can flexibly cope with tire sizes with a high inner expansion rate while contributing to cost reduction by effectively utilizing existing equipment. An object of the present invention is to provide an unvulcanized tire including an inner liner that can be effectively prevented to improve uniformity and internal pressure retention in a tire, and a pneumatic tire using the same.

In order to solve the above-mentioned problems, the present inventors have found an inner liner having a specific shape on at least a part of the surface, and have completed the present invention.
That is, the unvulcanized tire of the present invention is
An inner liner comprising a laminate including at least one barrier layer and two or more protective layers, wherein the barrier layer has a thickness of 1 to 30 μm, and the inner liner has both end portions. It has a foaming convex part and a foaming concave part on the joining surface arrange | positioned in the tire radial direction inner side at the time of joining, and surfaces other than this joining surface, It is characterized by the above-mentioned.

Also, the protective layer is preferably from a rubber composition, the rubber composition that comprises a polyurethane elastomer desirable.
The barrier layer may be made of at least one selected from the group consisting of an ethylene-vinyl alcohol copolymer, a modified ethylene-vinyl alcohol copolymer, nylon 6, and nylon 6,6.
Moreover, it is desirable that the laminate further includes an adhesive layer as a layer constituting the innermost layer in the tire radial direction.

  The pneumatic tire according to the present invention is obtained by vulcanizing the unvulcanized tire.

  According to the present invention, since an inner liner capable of effectively preventing joint cracking that may occur at the time of molding or after molding can be obtained, it is possible to realize a pneumatic tire having excellent uniformity and high internal pressure retention. It becomes possible. In addition, it is possible to flexibly cope with tire sizes having a high inner expansion rate, and it is possible to contribute to cost reduction by effectively utilizing existing equipment.

FIG. 1 is a cross-sectional view of the green case at the molding stage. FIG. 2 shows a state in which both end portions of an inner liner made of a two-layer laminate of one barrier layer and one protective layer are overlapped and joined in the H portion including the joint portion of the inner liner in FIG. FIG. FIG. 3 is a partial cross-sectional view showing an inner liner composed of a laminate of two barrier layers and two protective layers in the inner liner of the unvulcanized tire of the present invention. FIG. 4 is a partial cross-sectional view showing an inner liner composed of a laminate of two barrier layers, three protective layers, and one adhesive layer in the inner liner of the unvulcanized tire of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings as necessary.
The unvulcanized tire of the present invention is
An inner liner made of a laminate including at least one barrier layer is provided, and a convex portion is formed on a bonding surface of one end portion disposed on the inner side in the tire radial direction when the both end portions of the inner liner are overlapped and bonded. It is characterized by having a recess.
Moreover, it is preferable that the said laminated body contains an at least 1 layer of protective layer, and the said recessed part and the said convex part are a foaming convex part and a foaming convex part, respectively.

  First, a general molding process of an unvulcanized tire for obtaining a pneumatic tire will be described with reference to FIG. Unvulcanized tires usually undergo a two-stage molding process. In the first first molding stage, the inner liner 1 and the carcass ply 2 are pasted on the molding drum, a pair of bead cores 5 are driven in, the carcass ply 2 is folded around, and the bead portion reinforcing cord layer 6 is formed as necessary. Paste together. The bead portion reinforcing cord layer 6 may be bonded to the carcass ply 2 in advance. Next, a sidewall rubber 7 is attached to obtain a cylindrical green case 3.

  In the subsequent second molding stage, the green case 3 is narrowed toward the center C of the cross section while the devices for clamping the pair of bead portions 10 are narrowed toward each other, and the mutual distance between the pair of bead portions 10 is reduced. It is filled with low-pressure air and expanded in the outer diameter direction. At this time, a composite member in which an unvulcanized tread rubber 11 is pasted on the outer periphery of the belt member 4 is pasted on the surface of a cylindrical drum whose diameter can be reduced and expanded in advance, and this is aligned with the center C of the cross section of the green case 3. However, the green case 3 expanded while folding the unvulcanized tread rubber 11 as necessary is brought into contact with the inner peripheral surface of the belt member 4 to obtain an unvulcanized tire. Then, a pneumatic tire is obtained by taking out the unvulcanized tire which passed through the molding process from a molding machine, and performing a vulcanization treatment.

  Here, when the inner liner 1 is attached to a molding drum, both ends of the inner liner 1 are overlapped and joined while being wound around the molding drum. That is, one end of the inner liner 1 is disposed inside the tire diameter, and the other end is overlapped from above. Both ends of the overlapped inner liner 1 are also called joint parts, but if this part is not sufficiently bonded, stress is applied when the green case 3 is inflated in the second molding stage or when the tire is used. When it is done, there is a risk that peeling or cracking (joint cracking) may occur at the joint part, or the uniformity may be reduced.

The inner liner 1 of unvulcanized rubber according to the present invention is disposed on the inner side in the tire radial direction when the two end portions of the inner liner 1 are overlapped and joined as shown in the schematic cross-sectional view of FIG. The joining surface S _x of one end part x has a foamed convex part and a foamed concave part. In FIG. 2A, an example in which the inner liner 1 is composed of a laminate having a two-layer structure of one protective layer 21 and one barrier layer 22, and the protective layer 21 constitutes the bonding surface _Sx. Show. The foam-like convex part and the foam-like concave part are pressed from the pressing direction B in the expansion process in the second molding stage to develop an anchor effect, and one end x disposed on the inner side in the tire radial direction and the end The adhesive force with the other end portion y superimposed from the upper surface of the portion x can be improved. Therefore, it is possible to obtain the inner liner 1 that can maintain the state where both end portions x and y are firmly fixed even after the second molding step and when the tire is used. Here, the foam-like convex part and the foam-like concave part only have to be present on at least the joining surface S _x of one end part arranged on the inner side in the tire radial direction, and are shown in the schematic cross-sectional view of FIG. As shown, you may have over the whole surface S which comprises this joining surface _Sx . However, it is possible to improve the adhesion between the inner liner 1 and other adjacent members such as the carcass ply 2 while improving the adhesion between both ends of the joint portion of the inner liner. Therefore, it is desirable to have a convex portion and a concave portion over the entire surface S of the layer constituting the bonding surface.

  In the present specification, the foamed convex portion and the foamed concave portion are a part of an afterimage of bubbles formed after a plurality of closely spaced bubbles burst (break) among the convex portions and the concave portions. The convex part and the recessed part which approximated a certain shape are meant, The part which protruded from the surface among such shapes is called a foaming convex part, and the part which depressed from the surface is called a foaming recessed part.

Inner liner of the unvulcanized rubber according to the present invention comprises a laminate comprising at least one layer barrier layer, further comprising at least one layer protective layer. By including at least one barrier layer, good gas barrier properties as an inner liner can be ensured. The barrier layer may be one layer or two or more layers. From the viewpoint of further improving gas barrier properties and internal pressure retention properties, the inner liner preferably includes two or more barrier layers.

  The layer forming the barrier layer is not particularly limited as long as it exhibits good gas barrier properties. For example, nylon 6, nylon 6,6, polybutadiene resin, maleic anhydride-modified polyethylene, maleic anhydride-modified polybutadiene , Ethylene-vinyl alcohol copolymer (EVOH), modified EVOH, polyethylene, polypropylene, polyethylene terephthalate (PET), vinylidene chloride, polybutylene terephthalate (PBT), vinyl acetate resin, and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of excellent gas barrier properties and greatly improving the internal pressure retention of the tire, selected from the group consisting of ethylene-vinyl alcohol copolymer, modified ethylene-vinyl alcohol copolymer nylon 6 and nylon 6,6 It is desirable to be at least one kind. If necessary, fillers such as carbon black and silica, crosslinking agents such as sulfur, diphenylguanidine (DPG), tetramethylthiuram disulfide (TMTD), tetramethylthiuram monosulfide (TMTM), 2-mercaptobenzo Thiazole zinc salt (ZnBDC), 2-mercaptobenzothiazole (MBT), 2-benzothiazolyl disulfide (MBTS), N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and Nt-butyl-2- The barrier layer may be formed by blending a crosslinking accelerator such as benzothiazole sulfenamide (BBS) and a crosslinking accelerator such as zinc white (zinc oxide).

  The layer thickness of the barrier layer may vary depending on the layer configuration of the inner liner 1 and the like, but is usually 1 to 30 μm, preferably 10 to 20 μm. Therefore, even if the inner liner 1 is a laminated body including a plurality of barrier layers, it is possible to easily realize a thin layer.

As described above, the unvulcanized rubber inner liner according to the present invention is composed of a laminate including at least one protective layer. By including at least one protective layer, it is possible to suppress the generation and extension of cracks by adding excellent reinforcing properties while realizing thinning of the inner liner . In addition, from the viewpoint of further improving the reinforcing property, the inner liner is a laminate including two or more protective layers . The protective layer preferably has closed cells. By having closed cells, it is easy to give foamed convex portions and foamed concave portions to the surface of the protective layer, and the protective layer can easily be a layer constituting the bonding surface _Sx .

  The layer for forming the protective layer is not particularly limited as long as it can exhibit the above-described good protective function and reinforcement, but a layer made of a rubber composition is suitable. Examples of such rubber compositions include natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber, butyl rubber, chloroprene rubber, acrylic rubber, urethane rubber, chlorinated polyethylene, and ethylene. -In addition to rubber components such as acrylic rubber, those containing olefin-based, styrene-based, ester-based, urethane-based, ionomer-based, 1,2-polybutadiene-based, polyamide-based thermoplastic elastomers, and the like. Especially, it is desirable to contain a urethane-type elastomer from a viewpoint of giving a foaming convex part and a foaming recessed part easily to the desired surface of an inner liner. At that time, the expansion ratio is usually 0.1 to 300%, preferably 1 to 200%, more preferably 1 to 150%.

  The urethane elastomer is obtained by a reaction of a polyol (long chain diol), an isocyanate compound, and a short chain diol. A polyol and a short chain diol form a linear polyurethane by an addition reaction with an isocyanate compound. Here, the polyol becomes a flexible part in the urethane elastomer, and the isocyanate compound and the short chain diol become a hard part.

  For example, the isocyanate compound is an organic polyisocyanate having two or more isocyanate groups in one molecule, and includes aliphatic and aromatic polyisocyanate compounds, and modified products thereof. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexane diisocyanate. Examples of the aromatic polyisocyanate include toluene diisocyanate, diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate. It is done. Examples of these modified products include carbodiimide modified products and prepolymer modified products.

  Examples of the polyol include low molecular polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, 1,2,6-hexanetriol, and pentaerythritol; ethylenediamine, 4,4′-methylene- Of bisphenol obtained by addition polymerization of an amine compound such as bis-2-chloroaniline, 4,4′-methylene-bis-2-ethylaniline, or a low molecular polyol or an amine compound with an alkylene oxide such as ethylene oxide or propylene oxide. Polyether polyols such as propylene oxide adducts; and polyhydric alcohols such as ethylene glycol, propylene glycol and 1,4-butanediol and phthalic acid, maleic acid, malonic acid, succinic acid, adip Acid, polyester polyol having terminal hydroxyl groups and a condensation polymerization product of a polybasic acid such as terephthalic acid, acrylic polyols, castor oil, or the like can be used tall oil.

  A urethane stock solution is prepared by blending these polyols with a catalyst, a foaming agent, and other additive components added as needed, and blending and mixing an isocyanate compound.

  Examples of the blowing agent include, for example, trichlorofluoromethane, chlorodifluoromethane, and other fluorocarbon compounds as low boiling point inert solvents, methylene chloride, water, acid amide, nitroalkane, etc. that generate gas by liquefied carbon dioxide reaction. Sodium bicarbonate, ammonium carbonate, or the like can be used as one that generates gas upon thermal decomposition. As the foam stabilizer, silicone oil or the like can be used.

  Examples of the catalyst include tin-based catalysts such as dibutyltin diurarate and stannous octoate, and tertiary amines such as triethylamine and tetramethylhexamethylenediamine.

  If necessary, the urethane stock solution may further contain a flame retardant and other additive components. Examples of the flame retardant include conventionally known flame retardants such as tris (2-chloroethyl) phosphate, tris (2,3-dibromopropyl) phosphate, etc., organic powders such as urea and thiourea, and metal hydroxide. Inorganic powder such as antimony trioxide can be used. Examples of other auxiliary agents include colored powders such as pigments and dyes, powders such as talc and graphite, short glass fibers, other inorganic extenders and organic solvents.

Note that the properties of the urethane elastomer can be appropriately varied over a wide range by changing the type, blending amount, polymerization conditions, and the like of the raw materials.
Moreover, you may mix | blend the above-mentioned filler, the crosslinking agent, the crosslinking accelerator, and the crosslinking promotion adjuvant with the said rubber composition as needed, and may form the said protective layer.

  The foamed convex portion and the foamed concave portion may be provided on the surface of the barrier layer 22, but from the viewpoint of ensuring a good gas barrier property by the barrier layer 22, the foamed convex portion and the foamed concave portion are provided on the surface of the protective layer 21. desirable. Further, as shown in FIG. 3 showing the inner liner 1 made of a laminate including two barrier layers and two protective layers, the protective layer 21 is formed on a surface T other than the surface S constituting the bonding surface. And may have a foam-like convex part and a foam-like concave part. Thus, by having foamed convex portions and foamed concave portions on the surface T other than the surface S, it is possible to improve interlayer adhesion in the laminate of the inner liner 1 and effectively prevent delamination. It is also possible to improve the reinforcement of the inner liner itself.

  The inner liner 1 of unvulcanized rubber according to the present invention may be composed of a laminate including an adhesive layer 23 as shown in FIG. 4 in addition to the barrier layer 22 and the protective layer 21. By including the adhesive layer 23, the adhesiveness at the joint portion of the inner liner 1 can be further improved, and the inner liner 1 and the adjacent member are immediately bonded to effectively peel off the members at the time of tire molding. Can be prevented. Specifically, for example, this is effective when the inner liner 1 is stuck on the molding drum via a rubber member that is easy to stick to the molding drum while avoiding damage or the like of the thinned inner liner 1. FIG. 4 shows an example in which two barrier layers 22 and three protective layers 21 are provided, and an adhesive layer 23 is provided as the innermost layer in the tire radial direction. Even in this case, from the viewpoint of improving the interlayer adhesion between the protective layer 21 and the adhesive layer 23, it is desirable that the surface T of the protective layer 21 has a foamed convex portion and a foamed concave portion.

  The layer forming the adhesive layer 23 is not particularly limited as long as it is usually used for a tire member. For example, 1,4-phenylene dimaleimide is added to rubber components such as butyl rubber, halogenated butyl rubber, and diene rubber. A layer made of an adhesive composition containing a maleimide derivative such as poly-p-dinitrosobenzene is suitable. In addition, from the viewpoint of improving physical properties such as weather resistance, ozone resistance, and heat resistance, chlorosulfonated polyethylene may be further added to the rubber component.

  The method for producing an inner liner of unvulcanized rubber according to the present invention includes foaming the joining surface of one end portion disposed on the inner side in the tire radial direction when the two end portions of the inner liner described above are overlapped and joined. The surface is provided with a foamy convex part and a foamy concave part. By making it foam, a foaming convex part and a foaming concave part can be easily formed in the desired surface of an inner liner.

  In the foaming, for example, when both end portions of the inner liner are overlapped and joined, a layer constituting the joining surface of one end portion disposed on the inner side in the tire radial direction is used as a protective layer, and the protective layer is made of urethane elastomer. What is necessary is just to consist of a rubber composition to contain, it can be made to foam easily by heating, and a foaming convex part and a foaming concave part will be formed when a bubble bursts on the layer surface.

  The inner liner, for example, first forms a layer for imparting a foamed convex part and a foamed concave part in the same manner as described above, and forms the foamed convex part and the foamed concave part on the surface by heating. Subsequently, the compounding component for forming another layer is made into a pellet form, and a multilayer is formed using a multilayer co-extruder having a T-die for multilayer together with the foamed layer. In addition, when forming an adhesive layer, you may form by apply | coating an adhesive liquid at the last process.

  The pneumatic tire of the present invention is characterized by using the unvulcanized tire of the present invention as shown in FIG. As described above, one end portion having a foamed convex portion and a foamed concave portion on the surface of both end portions of the inner liner 1 is usually arranged on the inner side in the tire radial direction on the molding drum in the first molding stage. The other end is overlapped from the upper surface. Next, a desired adjacent member is pasted and expanded to obtain an unvulcanized tire. At this time, the inner liner 1 of the present invention is pressed from the pressing direction B and firmly fixed at the joint portion, and there is no possibility of peeling.

  Thereafter, in the second molding stage, the vulcanized tire is vulcanized under known vulcanization conditions. As the conditions for the vulcanization treatment, for example, the vulcanization treatment is performed at a temperature of 100 ° C. or higher, preferably 125 to 200 ° C., more preferably 130 to 180 ° C. Even at this stage, the inner liner will be further expanded, but since the joint part is firmly fixed as described above, there is no risk of cracks occurring in such a part, and the uniformity with the desired size is achieved. The tire can be high. Next, the pneumatic tire of the present invention is obtained by filling with air, nitrogen, helium or the like.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Example)
In the examples, first, a thermoplastic polyurethane added with a foaming agent (Kuraray Co., Ltd., Kuramylon 3190) was heated to form a layer having foamed convex portions and foamed concave portions on the surface. Subsequently, the modified ethylene-vinyl alcohol copolymer is formed into a pellet shape and formed into a multilayer using a foamed layer using a two-type three-layer coextrusion apparatus to obtain three layers (thermoplastic foamed polyurethane layer / modified EVOH layer / A laminate composed of a thermoplastic foam polyurethane layer was produced.

Extrusion conditions Extrusion temperature :: C1 / C2 / C3 / die = 170/170/200/200 ° C.
Thermoplastic foamed polyurethane: 25mmφ extruder P25-18AC [manufactured by Osaka Seiki Co., Ltd.]
Modified EVOH (D): 20 mmφ extruder lab machine ME type CO-EXT [manufactured by Toyo Seiki Co., Ltd.]
T-die specification: 500mm width, 2 types, 3 layers [Plastic Engineering Laboratory Co., Ltd.]
Cooling roll temperature: 50 ° C
Pickup speed: 4m / min

  Thereafter, 100 parts by mass of the following adhesive composition was added to 1000 parts by mass of toluene (δ value: 18.2 MPa1 / 2), and dispersed or dissolved to prepare a coating solution. The obtained coating solution was applied to one side of an oxidized film (a monolayer film having a thickness of 20 μm made of a modified ethylene-vinyl alcohol copolymer) and then dried to form an adhesive layer. After laminating the above laminate on the surface of the layer, vulcanization treatment is performed at 160 ° C. for 15 minutes, so that four layers (from the outer side in the tire radial direction, from the protective layer (1) made of thermoplastic foam polyurethane / modified EVOH) An inner liner made of a barrier layer / a protective layer (2) made of thermoplastic foam polyurethane / adhesive layer) was prepared.

-Preparation of Adhesive Composition For 100 parts by mass of brominated butyl rubber [JSR, Bromobutyl 2244], 10 parts by mass of carbon black [Tokai Carbon Co., Ltd., Seast NB], phenol resin [Sumitomo Bakelite ( Co., Ltd., PR-SC-400] 20 parts by mass, stearic acid [manufactured by Shin Nippon Rika Co., Ltd., 50S] 1 part by mass, zinc oxide [manufactured by Hux Itec Corp.] 3 parts by mass, poly-p-dinitroso Benzene [Ouchi Shinsei Chemical Co., Ltd., Barnock DNB] 3 parts by mass, 1,4-phenylene dimaleimide [Ouchi Shinsei Chemical Co., Ltd., Barnock PM] 3 parts by mass, vulcanization accelerator ZTC [ Ouchi Shinsei Chemical Co., Ltd., Noxeller ZTC, 1 part by weight of zinc dibenzyldithiocarbamate], vulcanization accelerator DM [Ouchi Shinsei Chemical Co., Ltd., Noxeller DM, di-2-benzothiazo Ludisulfide] 0.5 parts by mass, Vulcanization accelerator D [Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller D, 1,3-diphenylguanidine] 1 part by mass and Sulfur [Tsurumi Chemical Co., Ltd., Kinka seal Fine powder sulfur] 1.5 parts by mass was blended to prepare an adhesive composition.

(Comparative example)
A four-layer structure (made of thermoplastic polyurethane) under the same conditions as in Examples except that a laminate was produced using ordinary thermoplastic polyurethane (Kuraray 3190, manufactured by Kuraray Co., Ltd.) without adding a foaming agent. An inner liner of protective layer (1) / barrier layer made of modified EVOH / protective layer (2) made of thermoplastic polyurethane / adhesive layer) was prepared.

(Evaluation)
After each inner liner of the example and comparative example is wound around the molding drum in the tire manufacturing process together with other members, and then left for one day with the case inflated in the second molding stage. Evaluation was performed by confirming whether or not the inner liner was peeled off at the joint portion of the film.
The evaluation results are shown in Table 1.

(result)
From Table 1, it was found that for the inner liner of the example, the joint portion of the film after leaving for 1 day was not peeled off, and the joint cracking was effectively suppressed. On the other hand, it was found that the inner liner of the comparative example was peeled off and the joint cracking was not sufficiently suppressed.

  According to the present invention, an unvulcanized tire having an inner liner that can effectively prevent joint cracking that may occur during molding or after molding is obtained, so that the pneumatic has excellent uniformity and high internal pressure retention. A tire can be realized. As a result, it is possible to flexibly cope with a tire size having a high inner expansion rate, and it is possible to effectively utilize existing facilities and contribute to cost reduction.

1: Inner liner 2: Carcass ply 3: Green case 5: Bead core 6: Bead portion reinforcing cord layer 7: Side wall rubber 10: Bead portion 11: Unvulcanized tread rubber 21: Protective layer
22: Barrier layer 23: Adhesive layer A: Molding drum B: Pressing direction C: Center of the cross section of the green case x: One end portion of the inner liner y: The other end portion of the inner liner S _x : Joining surface S of the inner liner S : Inner liner surface

Claims (6)

An inner liner made of a laminate including at least one barrier layer and two or more protective layers;
The barrier layer has a thickness per layer of 1 to 30 μm,
The inner liner has a foaming convex part and a foaming concave part on a joining surface disposed on the inner side in the tire radial direction when both ends are joined together and on a surface other than the joining surface. Sulfur tire.   The unvulcanized tire according to claim 1, wherein the protective layer is made of a rubber composition.   The unvulcanized tire according to claim 2, wherein the rubber composition includes a polyurethane-based elastomer.   The said barrier layer consists of at least 1 sort (s) chosen from the group which consists of ethylene-vinyl alcohol copolymer, modified ethylene-vinyl alcohol copolymer, nylon 6, and nylon 6,6. An unvulcanized tire according to any one of the above.   The unvulcanized tire according to any one of claims 1 to 4, wherein the laminate further includes an adhesive layer as a layer constituting the innermost layer in the tire radial direction.   A pneumatic tire obtained by vulcanizing the unvulcanized tire according to any one of claims 1 to 5.