WO2017199816A1

WO2017199816A1 - Pneumatic tire

Info

Publication number: WO2017199816A1
Application number: PCT/JP2017/017717
Authority: WO
Inventors: 雅也三田
Original assignee: 横浜ゴム株式会社
Priority date: 2016-05-16
Filing date: 2017-05-10
Publication date: 2017-11-23
Also published as: JP2017206052A; JP6233449B2

Abstract

Provided is a pneumatic tire wherein holes are provided in the film forming an inner liner, thereby suppressing tire failure caused by the splice portion of the inner liner. This pneumatic tire has a tire inner peripheral surface with an inner liner member 1 which is configured from an at least three-layer structure comprising: a film 2 that contains, as a main component, a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer; and rubber sheets 3A, 3B that are laminated on either side of the film 2. This pneumatic tire also has a lap-spliced portion where the ends of the film 2 in the tire circumferential direction overlap each other with the rubber sheets 3A, 3B interposed therebetween. The lap-spliced portion comprises a plurality of holes 6 in at least an end of the film 2 on the inside in the radial direction of the tire.

Description

Pneumatic tire

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which a hole portion is provided in a film constituting an inner liner to suppress a tire failure caused by a splice portion of the inner liner.

More specifically, an inner liner member including a film mainly composed of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer is formed on the inner surface of the tire, and an end portion in the tire circumferential direction is provided. The present invention relates to a pneumatic tire having a structure in which the tires are overlapped and spliced to each other, and the occurrence of a tire failure during vulcanization molding or running is suppressed.

In recent years, the use of a film mainly composed of a thermoplastic resin or a thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer as an inner liner member has reduced the overall weight of the tire and increased air permeability. Various studies have been made to achieve both high prevention performance (see, for example, Patent Documents 1 to 3).

For example, an inner liner composed of at least a three-layer structure of a film mainly composed of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber sheet laminated on both sides thereof. In order to use such an inner liner member as a tire structural member, the inner liner member is wound around a tire molding drum and its end is wrapped. A manufacturing method is employed in which the material is spliced and used for a tire vulcanization process (see, for example, Patent Documents 4 and 5).

Specifically, the inner liner member having such a laminated structure is wound around a tire molding drum so as to have a cylindrical shape, and at that time, both end portions in the circumferential direction are lap-spliced and used for a tire vulcanization molding process. Thus, a method of manufacturing a pneumatic tire is taken.

When using such a method, using an inner liner member composed of at least a three-layer structure of a film and rubber sheets laminated on both sides of the film means that the rubber sheets are overlapped and lap spliced. This is preferable because the splice can be reliably performed.

However, during the process from vulcanization molding to immediately after molding, phenomena such as peeling at the interface between the film and the rubber sheet and opening (openings) of the joint (splice part) may occur. It was.

This will be described with reference to FIG. 5A. As shown in FIG. 5A, a film 2 mainly composed of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and both sides thereof. The inner liner member 1 composed of at least a three-layer structure of

rubber sheets

3A and 3B laminated on each other is formed in a required size (length) determined according to the tire size, and is shown by a two-dot chain line as a model. On the tire forming drum 5, lap splice portions 4 are provided at both ends thereof, and the lap splices are overlapped so as to form an annular shape as a whole. The rubber sheet 3 </ b> B has a function as a tie rubber having a function of joining with other tire constituent members such as a carcass layer. In FIG. 5 (a) ~ (c) , an arrow Tc is the tire circumferential direction, arrow Tr _in the tire radial direction inner side, the arrow Tr _out indicates the tire radial direction.

The lap splice portion 4 of the inner liner member 1 is a process from green tire molding to vulcanization molding, as shown in FIG. 5B, particularly at the interface between the film 2 and the rubber sheet 3A, particularly near the end portion. The peeling state 7 may occur at the interface. For example, since the rubber sheet 3A constituting the inner liner member 1 has high adhesion (tack) with the surface of the molding drum 5, when the green tire is molded and removed from the molding drum 5, the end of the rubber sheet 3A The vicinity is pulled to the molding drum 5 side, and a peeling state 7 may occur at the interface between the film 2 and the rubber sheet 3A.

The inner liner member after vulcanization molding forms the inner liner layer 10 as a whole, as shown in FIG. In the vicinity of the lap splice portion 4, the end portions of the film 2 overlap with each other through a member made of a rubber sheet. In the region surrounded by the alternate long and short dash line 8 in the vicinity of the tip 8 of the film 2 shown in FIG. 5 (c), it is noted that tire failure such as peeling of the film 2 and the rubber member occurs during molding and running of the pneumatic tire. This is where it should be.

Japanese Laid-Open Patent Publication No. 8-217923 International Publication No. 2008/53747 International Publication No. 2012/086276 Japanese Unexamined Patent Publication No. 2006-198848 Japanese Unexamined Patent Publication No. 2012-6499

An object of the present invention is to provide a pneumatic tire that suppresses a tire failure caused by a splice portion of an inner liner by providing a hole in a film constituting the inner liner.

In order to achieve the above object, a pneumatic tire according to the present invention comprises a film composed mainly of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and laminated on both sides thereof. A pneumatic tire having an inner liner member composed of at least a three-layer structure of a rubber sheet formed on the inner peripheral surface of the tire, and a lap splice portion in which tire circumferential ends of the film overlap with each other via the rubber sheet In the lap splice portion, at least an end portion of the film located on the inner side in the tire radial direction is provided with a plurality of hole portions.

In the present invention, the rubber sheet penetrates the film during vulcanization molding so that the rubber sheets are in direct contact with each other by providing a plurality of holes at the end of the film located at the inner side in the tire radial direction in the lap splice portion. For this reason, the lap splice can be firmly joined. As a result, it is possible to prevent the lap splice part from peeling off and opening (opening) at the time of vulcanization molding of the tire, and to suppress the occurrence of a tire failure such as a crack occurring near the lap splice part during running. It becomes possible.

In the present invention, it is preferable that the hole is arranged closer to the front end of the film as it is closer to the tire center line. In general, the closer to the tire center line, the more easily the film and rubber sheet peel off at the lap splice. Therefore, by arranging the hole closer to the tip of the film in the region closer to the tire center line, the effect of suppressing the peeling phenomenon between the film and the rubber sheet can be evenly exhibited in the width direction of the film, and the tire It is possible to effectively suppress a tire failure such as peeling of a film and a rubber sheet at the time of sulfur molding and traveling.

In the present invention, the total area of the holes arranged in the film is preferably in the range of 10% or more and less than 50% of the area of the lap splice part. By attaching the hole in this manner, it is possible to effectively suppress a tire failure such as peeling of the film and the rubber sheet at the time of vulcanization molding and running of the tire. More preferably, it is 25% or more and 35% or less.

In the present invention, the length S in the tire circumferential direction of the lap splice portion is preferably 5 mm or more and less than 30 mm. Thus, by appropriately setting the size of the lap splice portion, it is possible to effectively suppress a tire failure such as peeling of the film and the rubber sheet during vulcanization molding and running of the tire. More preferably, it is 7 mm or more and 15 mm or less.

FIG. 1 is a partially broken perspective view showing an example of an embodiment of a pneumatic tire according to the present invention, illustrating the positional relationship of a lap splice portion of an inner liner member in the tire. FIG. 2 shows an example of an embodiment of a lap splice portion in the inner liner member of the pneumatic tire of the present invention, and is a cross-sectional view showing an enlarged part of a cross section in the tire equator direction. FIG. 3 is a plan view showing a circumferential end of the film constituting the inner liner member of FIG. FIG. 4 is a plan view showing a circumferential end of a modification of the film constituting the inner liner member of FIG. 5 (a), (b), and (c) schematically illustrate a section in the tire equator direction of a lap splice portion of an inner liner member in a conventional pneumatic tire. FIG. 5 (a) FIG. 5B shows a state in which the inner liner member is formed in an annular shape on a spliced tire molding drum with both circumferential ends overlapped, and FIG. 5B shows a state where the tire is molded in the state shown in FIG. FIG. 5C is a cross-sectional view illustrating the structure of the spliced portion after vulcanization, schematically showing a state where peeling occurs between the film and the rubber sheet.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a partially broken perspective view showing an example of an embodiment of a pneumatic tire of the present invention. In FIG. 1, the arrow Tc indicates the tire circumferential direction, and the arrow Tw indicates the tire width direction.

As shown in FIG. 1, the pneumatic tire T is provided so that the sidewall portion 12 and the bead portion 13 are connected to the left and right of the tread portion 11. On the inside of the tire, a carcass layer 14 which is a skeleton of the tire is provided so as to straddle between the left and

right bead portions

13 and 13 in the tire width direction, and the tire is arranged around the bead core 16 disposed in each bead portion 13. Folded from inside to outside. Two belt layers 15 made of steel cord are provided on the outer peripheral side of the carcass layer 14 corresponding to the tread portion 11. An inner liner layer 10 is disposed inside the carcass layer 14 and a lap splice portion 4 extends in the tire width direction.

As shown in FIG. 2, the pneumatic tire of the present invention has an inner liner member 1 on its inner peripheral surface, and has a lap splice structure in which ends on both sides in the tire circumferential direction overlap and are spliced. The inner liner member 1 is composed of at least a three-layer structure of a film 2 and

rubber sheets

3A and 3B laminated on both sides thereof. The film 2 is a film mainly composed of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer. In addition, in FIG. 2, the cross section of the main body of the film 2 and

rubber sheet

3A, 3B is drawn in linear form for easy understanding. Actually, the film 2 and the

rubber sheets

3A and 3B extend with an appropriate curvature according to the size of the pneumatic tire.

When the inner liner member 1 is lap spliced, when one film 2 is used, both end portions in the circumferential direction of the film 2 are lap spliced via the

rubber sheets

3A and 3B to form an annular shape. Alternatively, when a plurality of films 2 are used, the circumferential ends of the films 2 are lap spliced via the

rubber sheets

3A and 3B so that the films 2 are connected to form a single ring as a whole. Formed as follows. In addition, the bonding between both ends of the inner liner member 1 (film 2) is a structure in which the films 2 overlap each other via the

rubber sheets

3A and 3B, and the rubber-rubber is vulcanized and bonded, so that the adhesive force is large.

The film 2 constituting the inner liner member 1 has an end portion 2A located on the inner side in the tire radial direction and an end portion 2B located on the outer side in the tire radial direction in the lap splice portion 4. A plurality of holes 6 are formed in the end portion 2A of the film 2 located at least on the inner side in the tire radial direction in the lap splice portion 4. As shown in FIG. 3, these hole portions 6 are all provided in the region of the lap splice portion 4, and are arranged at equal intervals along the width direction of the film 2. In FIG. 3, the hole 6 having a circular shape in a plan view is depicted, but the shape of the hole 6 is not particularly limited. For example, the slit shape including a straight cut, an ellipse, a triangle, A quadrangle, rhombus, polygon or the like can be adopted. 2 illustrates the case where the hole 6 is formed only at the end 2A of the film 2, but the hole 6 is formed at both ends 2A and 2B of the film 2. You can also. That is, it is sufficient that the film 2 is formed at least at the end 2A among the both ends 2A and 2B.

In the pneumatic tire described above, the

rubber sheets

3A and 3B penetrate the film 2 at the time of vulcanization molding by providing a plurality of holes 6 at the end 2A of the film 2 located at least inside the tire radial direction in the lap splice portion 4. And since

rubber sheet

3A, 3B contacts directly, the joining of the lap | splice part 4 can be strengthened. As a result, it is possible to prevent the lap splice portion 4 from peeling off or opening (opening) at the time of vulcanization molding of the tire T, and to generate a tire failure such as a crack occurring near the lap splice portion 4 during traveling. Can be suppressed.

As shown in FIG. 4, the hole 6 is preferably disposed closer to the tip of the film 2 as it is closer to the tire center line CL. That is, when comparing the plurality of hole portions 61 located closer to the tire center line CL and the plurality of hole portions 62 located on the outer side in the tire width direction than the hole portions 61, the hole portions 61 are close to the front end of the film 2. The hole 62 is disposed at a position farther from the tip of the film 2 than the hole 61. The position of the hole 6 may be gradually displaced from the tire center line CL toward the outside in the tire width direction, or may be gradually changed. In any case, the distance from the center position of the hole 6 closest to the tire center line CL to the tip of the film 2 is desirably 1 mm to 3 mm.

In the present invention, the hole 6 is arranged closer to the tip of the film 2 in a region closer to the tire center line CL, thereby suppressing the peeling phenomenon between the film 2 and the

rubber sheets

3A, 3B in the width direction of the film 2 evenly. Can be demonstrated. As a result, it is possible to effectively suppress tire failures such as peeling of the film 2 and the

rubber sheets

3A and 3B during vulcanization molding and running of the tire T.

As described above, the hole 6 is arranged closer to the tip of the film 2 as it is closer to the tire center line CL, or instead of being arranged closer to the tip of the film 2 as it is closer to the tire center line CL. Further, the closer to the tire center line CL, the smaller the interval between the holes 6 can be made. Also in this case, the effect of suppressing the peeling phenomenon between the film 2 and the

rubber sheets

3A and 3B can be evenly exhibited in the width direction of the film 2.

The area of each hole 6 arranged at the end 2A of the film 2 is defined as an area Z. The area Z is preferably 0.25 to 80.0 mm ² , more preferably 3.0 to 30.0 mm ² . Further, the total area Z1 is defined as the total area Z1 of all the holes 6 arranged at the end 2A of the film 2, and the length S of the lap splice portion 4 in the tire circumferential direction and the width W of the film 2 are Let the area calculated | required from a product be the area Z2 of the lap splice part 4. FIG. At this time, the total area Z1 of the hole 6 is preferably in the range of 10% to less than 50%, more preferably 25% to 35% with respect to the area Z2 of the lap splice part 4, respectively. Thus, by appropriately setting the total area Z1 with respect to the area Z2, it is possible to effectively suppress tire failures such as peeling of the film 2 and the

rubber sheets

3A and 3B during vulcanization molding and running of the tire. It becomes possible. Here, when the total area Z1 of the hole 6 is smaller than 10% with respect to the area Z2 of the lap splice part 4, the effect of suppressing the peeling phenomenon is reduced, and on the other hand, when the total area Z1 is 50% or more, the leading edge of the film 2 is reduced. The rigidity of the tire may be excessively lowered, and the work efficiency may be significantly deteriorated in the tire molding process.

In the present invention, the length S in the tire circumferential direction of the lap splice portion 4 in which both ends 2A and 2B in the tire circumferential direction of the film 2 overlap each other is preferably 5 mm or more and less than 30 mm, more preferably 7 mm or more and 15 mm or less. good. By appropriately setting the dimensions of the lap splice portion 4 in this way, it is possible to effectively suppress tire failures such as peeling of the film 2 and the

rubber sheets

3A and 3B during vulcanization molding and running of the tire T. It becomes. Here, if the length S in the tire circumferential direction of the lap splice portion 4 is smaller than 5 mm, a sufficient amount of splice cannot be ensured, and an opening is likely to occur. On the other hand, when the length S in the tire circumferential direction of the lap splice portion 4 is 30 mm or more, the rigidity of the lap splice portion 4 becomes excessive with respect to the peripheral region, and the uniformity of the tire may be reduced. is there.

In the present invention, the film 2 is a film mainly composed of a thermoplastic resin or a film mainly composed of a thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer.

As the resin that can be used for the film 2, a thermoplastic resin or a thermosetting resin can be used, but a resin containing a thermoplastic resin as a main component is preferable from the viewpoint of easy handling. Details of the thermoplastic resin will be described later. As the thermosetting resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, an unsaturated polyester, a silicon resin, a polyurethane resin, or the like is preferable.

Examples of the thermoplastic resin that can be used for the film 2 include polyamide resins [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12). , Nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 9T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer] and their N-alkoxyalkylated products (for example, methoxymethylated products of nylon 6, nylon 6 / 610 copolymer methoxymethylated, nylon 612 methoxymethylated, poly Stell resin (for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, Aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) Acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resin [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate], poly Vinyl resins [for example, polyvinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, Vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer (ETFE)], cellulose resin [for example, cellulose acetate, cellulose acetate butyrate], fluorine resin [for example, polyvinylidene fluoride (PVDF), polyfluoride Vinyl (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer], imide resin [for example, aromatic polyimide (PI)], or the like can be used.

Of these, polyester resins and polyamide resins are preferable in terms of physical properties, processability, and handleability.

Also, the thermoplastic resin-elastomer blend (thermoplastic elastomer composition) that can constitute the film 2 has a structure in which the elastomer is dispersed as a discontinuous phase in the thermoplastic resin matrix. By taking such a structure, it is possible to obtain molding processability equivalent to that of a thermoplastic resin. Among the thermoplastic resins and elastomers constituting the thermoplastic elastomer composition, those described above can be used for the thermoplastic resin. Examples of the elastomer constituting the thermoplastic elastomer composition include diene rubbers and hydrogenated products thereof [eg, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene] Rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubber [for example, ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber ( M-EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [eg, Br-IIR, CI-IIR, brominated isobutylene- p-methylstyrene copolymer (BIMS), chloroprene (CR), hydrin rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid modified chlorinated polyethylene rubber (M-CM)], silicone rubber [eg methyl vinyl silicone rubber Dimethylsilicone rubber, methylphenylvinylsilicone rubber], sulfur-containing rubber (for example, polysulfide rubber), fluorine rubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon) Rubber, fluorine-containing phosphazene rubbers], thermoplastic elastomers (for example, styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, polyamide elastomers) and the like are preferably used. Door can be.

In particular, when blending a plurality of elastomers, 50% by weight or more of them is a halogenated butyl rubber, a brominated isobutylene paramethylstyrene copolymer rubber or a maleic anhydride modified ethylene α-olefin copolymer rubber. It is preferable in that it can be increased in flexibility and durability from low to high temperatures.

Further, 50% by weight or more of the thermoplastic resin in the thermoplastic elastomer composition is nylon 11, nylon 12, nylon 6, nylon 66, nylon 6/66 copolymer, nylon 6/12 copolymer, nylon 6 / 10 copolymer, nylon 4/6 copolymer, nylon 6/66/12 copolymer, aromatic nylon, and ethylene / vinyl alcohol copolymer can provide excellent durability It is possible and preferable.

In addition, when preparing a thermoplastic elastomer composition by combining the above-mentioned specific thermoplastic resin and elastomer, if the compatibility between the two is insufficient, it is made compatible by using an appropriate compatibilizing agent as the third component. be able to. Mixing a compatibilizer with a blend of a thermoplastic resin and an elastomer reduces the interfacial tension between the thermoplastic resin and the elastomer, resulting in a finer particle size for the elastomer forming the dispersed phase. Therefore, the characteristics of both components are expressed more effectively. Such a compatibilizing agent generally includes a copolymer having a structure of both or one of a thermoplastic resin and an elastomer, or an epoxy group, a carbonyl group, a halogen group, and an amino group that can react with the thermoplastic resin or elastomer. In addition, a copolymer having a oxazoline group, a hydroxyl group and the like can be taken. These may be selected depending on the type of thermoplastic resin and elastomer to be blended, but those commonly used include styrene / ethylene butylene block copolymer (SEBS) and its maleic acid modification, EPDM, EPM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its modified maleic acid, styrene / maleic acid copolymer, reactive phenoxin and the like can be mentioned. The amount of the compatibilizing agent is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer).

In the thermoplastic elastomer composition, the composition ratio between the thermoplastic resin and the elastomer is not particularly limited. For example, the composition ratio may be appropriately determined so as to have a structure in which an elastomer is dispersed as a discontinuous phase in a thermoplastic resin matrix. The composition ratio between the thermoplastic resin and the elastomer is preferably a thermoplastic resin / elastomer weight ratio of 90/10 to 20/80, more preferably 80/20 to 30/70.

In the present invention, the thermoplastic elastomer or the thermoplastic elastomer composition obtained by blending a thermoplastic resin and an elastomer is, for example, within the range not impairing the characteristics necessary for constituting the film 2, other than the compatibilizers described above. In addition, other polymers can be mixed. The purpose of mixing other polymers is to improve the molding processability of the material, to improve heat resistance, to reduce costs, etc. Examples of materials used for this include polyethylene (PE), polypropylene ( PP), polystyrene (PS), ABS, SBS, polycarbonate (PC) and the like can be exemplified.

In addition, fillers (calcium carbonate, titanium oxide, alumina, etc.) generally incorporated into polymer blends, reinforcing agents such as carbon black and white carbon, softeners, plasticizers, processing aids, pigments, dyes, and aging An inhibitor or the like can be arbitrarily blended as long as the necessary properties as the film 2 are not impaired.

Also, the elastomer blended with the thermoplastic resin can be dynamically vulcanized upon mixing with the thermoplastic resin. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time), and the like in the case of dynamic vulcanization may be appropriately determined according to the composition of the elastomer to be added, and are not particularly limited.

Since the elastomer in the thermoplastic resin composition is dynamically vulcanized in this way, the resulting thermoplastic elastomer composition contains the vulcanized elastomer, and thus resists deformation from the outside. There is force (elasticity), and the effect of the present invention can be increased, which is preferable.

A general rubber vulcanizing agent (crosslinking agent) can be used as the vulcanizing agent. Specific examples of sulfur vulcanizing agents include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide, and the like. About 4 phr (in the present specification, “phr” refers to parts by weight per 100 parts by weight of the elastomer component; the same applies hereinafter).

Organic peroxide vulcanizing agents include benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxide). Examples thereof include oxy) hexane, 2,5-dimethylhexane-2,5-di (peroxylbenzoate), and about 1 to 20 phr can be used.

Further, examples of the phenol resin vulcanizing agent include bromides of alkyl phenol resins, mixed crosslinking systems containing halogen donors such as tin chloride and chloroprene, and alkyl phenol resins. For example, about 1 to 20 phr is used. Can do.

In addition, zinc white (about 5 phr), magnesium oxide (about 4 phr), risurge (about 10 to 20 phr), p-quinonedioxime, p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone, poly-p- Examples include dinitrosobenzene (about 2 to 10 phr) and methylenedianiline (about 0.2 to 10 phr).

Further, a vulcanization accelerator may be added as necessary. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate, and thiourea, such as 0.5 to About 2 phr can be used.

The rubber materials constituting the

rubber sheets

3A and 3B include diene rubbers such as natural rubber, isoprene rubber, epoxidized natural rubber, styrene butadiene rubber, hydrogenated styrene butadiene rubber, ethylene propylene rubber, and maleic acid modified ethylene. Olefin rubbers such as propylene rubber can be preferably used.

The film 2 is preferably laminated with an adhesive layer interposed in order to improve the adhesion with the

adjacent rubber sheets

3A and 3B. As the polymer constituting the adhesive layer, acrylate copolymers such as ultrahigh molecular weight polyethylene having a molecular weight of 1 million or more, preferably 3 million or more, ethylene ethyl acrylate copolymer, ethylene methyl acrylate resin, ethylene acrylic acid copolymer, etc. And their maleic anhydride adduct, polypropylene and its maleic acid modification, ethylene propylene copolymer and its maleic acid modification, polybutadiene resin and its maleic anhydride modification, styrene-butadiene-styrene copolymer, styrene An ethylene-butadiene-styrene copolymer, a fluorine-based thermoplastic resin, a polyester-based thermoplastic resin, or the like is preferably used.

In the present invention, the thickness of the film 2 is not particularly limited, but it is usually preferable to use a film having a thickness of about 0.002 to 0.3 mm. Further, the thickness of each of the

rubber sheets

3A and 3B is not particularly limited, but it is practical to use one having a thickness of 0.1 to 1.8 mm, preferably 0.2 to 1.0 mm. is there. Here, when the thickness of the

rubber sheets

3A and 3B is less than 0.1 mm, the laminating work on the film 2 is worsened, and the deterioration of the film 2 due to heat from the bladder during vulcanization is suppressed. It will be difficult to do. Moreover, since it will cause the weight increase of a tire when exceeding 1.8 mm, it is not desirable.

Hereinafter, the present invention will be further described with reference to examples, but the scope of the present invention is not limited to these examples.

Nine types having inner liner layers in which the shape of the hole portion of the film constituting the inner liner member and the length S in the tire circumferential direction of the lap splice portion are different as shown in Table 1 (conventional example, examples 1 to 8) 100 green tires (tire size 195 / 65R15H) were molded.

In each test tire, the film is a thermoplastic containing nylon 6/66 copolymer (N6 / 66) and brominated isobutylene-p-methylstyrene copolymer (BIMS) at a weight ratio of 50/50. The elastomer composition is the main component, and the thickness is set to 100 μm (0.1 mm), and the rubber sheet has a thickness of 0.5 mm in common.

Each test tire was evaluated by the method described below for the peel resistance (peel resistance) of the green tire.

(A) Peeling resistance (peeling resistance) in a green tire:
The inner peripheral surface of the completed green tire was visually observed, and the number of green tires where peeling occurred at the splice portion of the inner liner was counted. The obtained results are shown in the column of “Peeling resistance in green tires” in Table 1 as an index using the reciprocal of the number of green tires in which peeling occurred, with the conventional example being 100. A larger index means less peeling of the inner liner and better moldability.

The resulting green tires were vulcanized to produce 100 pneumatic tires each. The peel resistance (peel resistance) after the durability test of this pneumatic tire was evaluated by the method described below.

(B) Peeling resistance (peeling resistance) on product tires:
The manufactured pneumatic tire was attached to JATMA standard rim 15 × 6J, and air was charged to 120 kPa at the tire internal pressure. This tire was run on an indoor drum tester (drum diameter 1707 mm) in accordance with JIS D4230 for 80 hours at a load of 7.24 kN and a speed of 81 km / h. Thereafter, the inner surface of the tire at the splice portion of the inner liner was visually observed, and the number of product tires in which peeling and cracks occurred were counted. The obtained results are shown in the column of “Peeling resistance on product tires” in Table 1 as an index using the reciprocal of the number of product tires in which peeling and cracks occurred and taking the conventional example as 100. The larger the index, the less the inner liner peels, and the better the tire durability.

As can be seen from Table 1, by providing a hole in the film, the tires of Examples 1 to 8 were peeled off and cracked in the vicinity of the lap splice portion both when the green tire was molded and after the durability test. It can be seen that this is a pneumatic tire that is suppressed and has few failures.

DESCRIPTION OF SYMBOLS 1 Inner liner member 2 Film 2A End part located inside tire radial direction 2B End part located outside tire

radial direction

3A, 3B Rubber sheet 4 Lap splice part 5 Tire molding drum 6 Hole part 7 Peeling state 8 Near the front end of the film DESCRIPTION OF SYMBOLS 10 Inner liner layer 11 Tread part 12 Side wall part 13 Bead part 14 Carcass layer 15 Belt layer 16 Bead core T Pneumatic tire S The length of the lap splice part in the tire circumferential direction

Claims

Inner liner composed of at least a three-layer structure of a film composed mainly of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber sheet laminated on both sides thereof A pneumatic tire having a member on an inner circumferential surface of the tire and having a lap splice portion in which tire circumferential ends of the film overlap with each other via the rubber sheet, and at least radially inward in the lap splice portion A pneumatic tire comprising a plurality of holes at an end portion of the film positioned.
2. The pneumatic tire according to claim 1, wherein the hole portion is arranged closer to a front end of the film as being closer to a tire center line.
The pneumatic tire according to claim 1 or 2, wherein a total area of the hole portions is 10% or more and less than 50% of an area of the lap splice portion.
The pneumatic tire according to any one of claims 1 to 3, wherein a length S of the lap splice portion in a tire circumferential direction is 5 mm or more and less than 30 mm.