JP7091664B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more specifically, a laminate composed of a film of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, a rubber composition, and the laminate. The present invention relates to a pneumatic tire provided with a reinforcing layer arranged adjacent to the tire, which can prevent local deterioration of the reinforcing layer and improve durability.

It has been proposed to use a thermoplastic resin or a film formed of a thermoplastic elastomer composition composed of a thermoplastic resin and an elastomer as a tire component such as an inner liner layer. Such a film is subjected to a tire manufacturing process as a laminated body in which a rubber composition for adhesion is laminated on at least one side, and a lap splice portion is formed by superimposing the end portions of the laminated body in the tire circumferential direction. (See, for example, Patent Documents 1 to 3).

However, when the lap splice portion is formed by superimposing the end portions of the laminated body in the tire circumferential direction as described above, a structure in which the interlayer rubber layer is interposed between the film layers is formed in the lap splice portion. Air may permeate through such an interlayer rubber layer, and a slight amount of air leakage may occur. Since the area of the interlayer rubber layer occupying the tire circumference is small, the effect on the entire pneumatic tire is small, but it is said that local deterioration occurs in the reinforcing layer such as the carcass layer and the belt layer due to the above-mentioned air leakage. There's a problem. In particular, heavy-duty pneumatic tires for buses, trucks, etc. have high air pressure, so when the above-mentioned film is used as the inner liner layer, air leakage tends to increase, and local deterioration of the reinforcing layer tends to occur. Become.

Japanese Unexamined Patent Publication No. 2012-240658 International Publication No. 2016/063785 International Publication No. 2016/2060128

An object of the present invention is to arrange a laminate composed of a film of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer and a rubber composition adjacent to the laminate. It is an object of the present invention to provide a pneumatic tire provided with a reinforcing layer, which can prevent local deterioration of the reinforcing layer and improve durability.

Pneumatic tires for achieving the above object are a film of a thermoplastic elastomer composition composed of a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber composition laminated on at least one side of the film. It is provided with a laminated body made of In a pneumatic tire in which a lap splice portion is formed by being laminated at one place and an interlayer rubber layer made of the rubber composition is interposed between the layers of the film in the lap splice portion, the tire of the laminate in the lap splice portion. The lap length L in the circumferential direction satisfies the following formula (1), and in a region of 10 mm from the lap splice portion on both sides in the tire circumferential direction including the lap splice, in the tire circumferential direction of other tire components. It is characterized in that there is no lap splice portion in which the ends are overlapped with each other .
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)
However, Gf: the average thickness [mm] of the film other than the wrap splice portion.
Gg: Average thickness [mm] of the interlayer rubber layer in the wrap splice portion
Pf: Oxygen permeability coefficient of the film [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Pg: Oxygen permeability coefficient of the interlayer rubber layer [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Dc: Distance [mm] in the film thickness direction from the end of the film to the steel cord constituting the reinforcing layer.

The present inventor is a laminate composed of a film of a thermoplastic elastomer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and a rubber composition, and is arranged adjacent to the laminate and is made of steel. As a result of diligent research on pneumatic tires with a reinforcing layer composed of cords, the average thickness of each of the film and the interlayer rubber layer and the average thickness of the lap length required to prevent local deterioration of the reinforcing layer and The present invention was derived by deriving a relational expression based on the oxygen permeation coefficient and the distance in the film thickness direction from the end of the film of the wrap splice portion to the steel cord of the reinforcing layer.

In the present invention, a laminate composed of a thermoplastic resin or a film of a thermoplastic elastomer composition comprising a blend of a thermoplastic resin and an elastomer and a rubber composition laminated on at least one side of the film, and a laminate thereof. It is arranged adjacent to the laminate and includes at least one reinforcing layer composed of a steel cord, and the ends of the laminate in the tire circumferential direction are overlapped with each other at at least one place on the tire circumference to form a lap splice. In a pneumatic tire in which a portion is formed and an interlayer rubber layer made of a rubber composition is interposed between layers of the film in the lap splice portion, the lap length L of the laminate in the lap splice portion in the tire circumferential direction is described in the above formula (1). ) Is satisfied, so that the minimum required lap length L in the tire circumferential direction in the lap splice portion of the laminated body is secured, so that local deterioration of the reinforcing layer can be prevented and durability can be improved. .. Therefore, even in a heavy-duty pneumatic tire for buses, trucks, etc., it is possible to prevent local deterioration of the reinforcing layer and effectively improve the durability.

In the present invention, the film obtained by dividing the oxygen permeability coefficient Pf [10 ^-3 · mm · cc / (m ² · day · mmHg)] of the film by the average thickness Gf [mm] of the film other than the wrap splice portion. It is preferable that the oxygen permeability [10 ^-3 · cc / (m ² · day · mmHg)] and the maximum air pressure P [kPa] of the tire satisfy the relationship of Pf / Gf ≦ 50,000 / P. When the above film is used as an inner liner layer, sufficient air permeation prevention performance can be ensured and durability can be effectively improved.

In the present invention, the oxygen permeability coefficient Pf at a film temperature of 23 ° C. and a humidity of 65% is preferably 20 [ ^10-3 · mm · cc / (m ² · day · mmHg)] or less. This makes it possible to suppress an increase in cost and weight.

In the present invention, the average thickness Gf of the film other than the wrap splice portion is preferably 0.03 mm to 0.50 mm. As a result, it is possible to suppress defects during molding and prevent deterioration of uniformity.

In the present invention, the oxygen permeability coefficient Pg of the interlayer rubber layer at a temperature of 23 ° C. and a humidity of 65% is preferably 2000 [ ^10-3 · mm · cc / (m ² · day · mmHg)] or less. This makes it possible to prevent deterioration of uniformity.

In the present invention, the average thickness Gg of the interlayer rubber layer in the wrap splice portion is preferably 0.10 mm to 1.00 mm. As a result, it is possible to suppress defects during molding and prevent deterioration of uniformity.

In the present invention, it is preferable that the reinforcing layer is a carcass layer and the film is arranged on the inner surface side of the tire rather than the carcass layer. As a result, the occurrence of cracks can be suppressed and the durability can be effectively improved.

In the present invention, the oxygen permeability coefficient [10 ^-3 · mm · cc / (m ² · day · mmHg)] of the film and the interlayer rubber layer is JIS K-7126-2 under the conditions of a temperature of 23 ° C. and a humidity of 65%. It is measured in accordance with (isopressure method).

It is a partially crushed perspective view which showed an example of the embodiment of the pneumatic tire of this invention, and it explains the positional relationship in the tire of a lap splice part. It is sectional drawing which shows an example of embodiment of the lap splice part in the laminated body of the pneumatic tire of this invention, and shows a part of the cross section in the equator direction of a tire enlarged.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of an embodiment of a pneumatic tire of the present invention. FIG. 2 shows an example of an embodiment of a lap splice portion in a laminated body of pneumatic tires of the present invention. 1 and 2 show a carcass layer as an example of a reinforcing layer constituting the pneumatic tire of the present invention. In FIGS. 1 and 2, the arrow Tc indicates the tire circumferential direction, and the arrow Tw indicates the tire width direction.

The pneumatic tire shown in FIG. 1 is provided so that the sidewall portion 12 and the bead portion 13 are connected to each other on the left and right sides of the tread portion 11. Inside the tire, a carcass layer 14 (reinforcing layer), which is the skeleton of the tire, is provided so as to straddle between the left and right bead portions 13 in the tire width direction, and around the bead core 16 arranged in each bead portion 13. It is folded back from the inside to the outside of the tire. The carcass layer 14 is composed of a plurality of steel cords 14A extending in the tire radial direction. A two-layer belt layer 15 made of a steel cord is provided on the outer peripheral side of the carcass layer 14 corresponding to the tread portion 11. An inner liner layer 10 is arranged inside the carcass layer 14, and a lap splice portion 4 thereof extends in the tire width direction. That is, the inner liner layer 10 is arranged on the inner surface side of the tire with respect to the carcass layer 14.

In the pneumatic tire shown in FIG. 2, the laminate 1 is used as the inner liner layer 10, and the ends of the laminate 1 in the tire circumferential direction are overlapped with each other at at least one position on the tire circumference to have a lap splice structure. is doing. The laminate 1 is composed of a film 2 and at least a two-layer structure of a rubber composition 3 laminated on at least one side thereof. The film 2 is a film of a thermoplastic elastomer composition comprising a thermoplastic resin or a blend of a thermoplastic resin and an elastomer. The rubber composition 3 laminated on the film 2 is vulcanized and adhered to the film 2. In the wrap splice portion 4, an interlayer rubber layer 3A made of the rubber composition 3 is present between the layers of the film 2. In FIG. 2, the cross section of the main body of the film 2 and the rubber composition 3 is drawn in a straight line for easy understanding.

When one film 2 is used for wrap splicing the laminate 1, both ends of the film 2 in the tire circumferential direction are wrap spliced via the rubber composition 3 to form an annular shape. Alternatively, when a plurality of films 2 are used, the ends of each film 2 in the tire circumferential direction are lap-split via the rubber composition 3, so that the films 2 are joined to form one annular shape as a whole. It is formed to form. Further, as shown in FIG. 2, when the laminated body 1 is composed of a three-layer structure of the film 2 and the rubber composition 3 laminated on both sides thereof, the ends of the laminated body 1 in the tire circumferential direction are connected to each other. The bonding has a structure in which the films 2 overlap each other via the rubber composition 3, and the rubber-rubber are vulcanized and bonded to each other, so that the adhesive strength is high.

In the pneumatic tire, the lap length L of the laminated body 1 in the lap splice portion 4 in the tire circumferential direction is configured to satisfy the following formula (1). In the following formula (1), Gf is the average thickness [mm] of the film 2 other than the wrap splice portion 4, Gg is the average thickness [mm] of the interlayer rubber layer 3A in the wrap splice portion 4, and Pf is. The oxygen permeability coefficient of film 2 is [10 ^-3 · mm · cc / (m ² · day · mmHg)], and Pg is the oxygen permeability coefficient [10 ^-3 · mm · cc / (m ² ·) of the interlayer rubber layer 3A. Day · mmHg)], where Dc is the distance [mm] in the film thickness direction from the end of the film 2 to the steel cord (steel cord 14A in FIG. 2) constituting the reinforcing layer (carcus layer 14 in FIG. 2). Is.
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)

In the above formula (1), it is shown that the wrap length L needs to be increased so that the average thickness of the interlayer rubber layer 3A becomes thicker or oxygen easily permeates (the larger the Pg or Gg). On the other hand, if oxygen easily permeates in a portion other than the wrap splice portion 4 of the film 2 (if Pf / Gf indicating oxygen permeability, which will be described later becomes large), the oxygen permeating through the interlayer rubber layer 3A decreases. Since there is a tendency, the wrap length L can be shortened, and if the distance Dc in the film thickness direction from the end of the film 2 to the steel cord 14A constituting the carcass layer 14 becomes large, the distance to the carcass layer 14 can be increased. It is shown that the lap length L can be shortened because the influence is reduced. The lap length L is a measurement of the length in the tire circumferential direction from the tip of one end of the film 2 to the tip of the other end. The average thickness Gf of the film 2, the average thickness Gg of the interlayer rubber layer 3A, the oxygen permeability coefficient Pf of the film 2, the oxygen permeability coefficient Pg of the interlayer rubber layer 3A, and the steel cord constituting the reinforcing layer from the end of the film 2. The distance Dc in the film thickness direction is measured at the center position of the belt layer in the tire width direction.

In the above-mentioned pneumatic tire, the film 2 of the thermoplastic elastomer composition composed of the thermoplastic resin or the blend of the thermoplastic resin and the elastomer and the rubber composition 3 laminated on at least one side of the film 2 are separated. 1. In a pneumatic tire in which a lap splice portion 4 is formed by being overlapped at at least one position on the tire circumference and an interlayer rubber layer 3A made of a rubber composition 3 is interposed between layers of the film 2 in the lap splice portion 4. When the lap length L of the laminated body 1 in the tire circumferential direction in the portion 4 satisfies the above formula (1), the minimum necessary lap length L in the tire circumferential direction in the lap splice portion 4 of the laminated body 1 is secured. Therefore, it is possible to prevent local deterioration of the reinforcing layer and improve durability. Therefore, even in a heavy-duty pneumatic tire for buses, trucks, etc., it is possible to prevent local deterioration of the reinforcing layer and effectively improve the durability.

In the pneumatic tire, another tire component (for example, a region of 10 mm from the lap splice portion 4 on both sides in the tire circumferential direction including the lap splice portion 4) in the vicinity of the lap splice portion 4 of the laminate 1 (for example, It is preferable that there is no lap splice portion in which the end portions of the tire circumferential direction (such as the carcass layer) are overlapped with each other.

In the pneumatic tire, the average thickness Gf (see FIG. 2) of the film 2 other than the lap splice portion 4 is preferably 0.03 mm to 0.50 mm. By appropriately setting the average thickness Gf of the film 2 in this way, it is possible to suppress defects during molding and prevent deterioration of uniformity. Here, if the average thickness Gf of the film 2 is thinner than 0.03 mm, the film 2 tends to wrinkle during molding, and conversely, if it is thicker than 0.50 mm, the uniformity tends to deteriorate.

Further, it is obtained by dividing the oxygen permeability coefficient Pf [10 ^-3 · mm · cc / (m ² · day · mmHg)] of the film 2 by the average thickness Gf [mm] of the film 2 other than the wrap splice portion 4. It is preferable that the oxygen permeability [10 ^-3 · cc / (m ² · day · mmHg)] of the film 2 and the maximum air pressure P [kPa] of the tire satisfy the relationship of Pf / Gf ≦ 50,000 / P. By setting the oxygen permeability (Gf / Pf) of the film 2 appropriately with respect to the maximum air pressure P of the tire in this way, sufficient air permeation prevention performance is ensured when the film 2 is used as the inner liner layer 10. And the durability can be effectively improved. Here, if the oxygen permeability of the film 2 exceeds 50,000 / P, the air permeation prevention performance tends to decrease and the durability tends to decrease when the film 2 is used as the inner liner layer 10.

In particular, the oxygen permeability coefficient Pf of the film 2 at a temperature of 23 ° C. and a humidity of 65% is preferably 20 [10 ^-3 · mm · cc / (m ² · day · mmHg)] or less. As the lower limit, it is preferable to set it to 0.5 [10 ^-3 · mm · cc / (m ² · day · mmHg)] or more. By appropriately setting the oxygen permeability coefficient Pf of the film 2 in this way, it is possible to suppress an increase in cost and weight. Here, if the oxygen permeability coefficient Pf of the film 2 is larger than 20 [10 ^-3 · mm · cc / (m ² · day · mmHg)], it is necessary to increase the thickness of the inner liner layer 10 (laminated body 1). Therefore, it leads to an increase in cost and weight. If the oxygen permeability coefficient Pf of the film 2 is smaller than 0.5 [10 ^-3 · mm · cc / (m ² · day · mmHg)], the durability deteriorates and cracks are likely to occur.

In the pneumatic tire, the average thickness Gg (see FIG. 2) of the interlayer rubber layer 3A in the lap splice portion 4 is preferably 0.10 mm to 1.00 mm. By appropriately setting the average thickness Gg of the interlayer rubber layer 3A in this way, it is possible to suppress defects during molding and prevent deterioration of uniformity. Here, if the interlayer rubber layer 3A is thinner than 0.10 mm, the rubber composition 3 tends to wrinkle during molding, and conversely, if it is thicker than 1.00 mm, the uniformity tends to deteriorate.

Further, the oxygen permeability coefficient Pg of the interlayer rubber layer 3A at a temperature of 23 ° C. and a humidity of 65% is preferably 2000 [ ^10-3 · mm · cc / (m ² · day · mmHg)] or less. As the lower limit, it is preferable to set it to 50 [10 ^-3 · mm · cc / (m ² · day · mmHg)] or more. By appropriately setting the oxygen permeability coefficient Pg of the interlayer rubber layer 3A in this way, deterioration of uniformity can be prevented. Here, if the oxygen permeability coefficient Pg of the interlayer rubber layer 3A is larger than 2000 [10 ^-3 · mm · cc / (m ² · day · mmHg)], the wrap length L becomes excessively long, resulting in deterioration of uniformity. It leads to. If the oxygen permeability coefficient Pg of the interlayer rubber layer 3A is smaller than 50 [10 ^-3 · mm · cc / (m ² · day · mmHg)], the durability tends to deteriorate.

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

Examples of the thermoplastic resin that can be used for the film 2 include polyamide-based 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 [eg, methoxymethylated product of nylon 6, nylon 6 / 610 copolymer methoxymethylated product, nylon 612 methoxymethylated product, polyester resin [for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, poly Arilate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylene diimide diic acid / polybutylene terephthalate copolymer], polynitrile resin [for example, polyacrylonitrile (PAN), polymethacrylate Lonitrile, acrylonitrile / styrene copolymer (AS), (meth) acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resin [for example, polymethyl methacrylate (PMMA)) , Polyethyl methacrylate], polyvinyl-based resin [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-based resin [for example, cellulose acetate, cellulose acetate butyrate], fluororesin [for example, polyfluoride Vinylidene (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer], imide-based resin [for example, aromatic polyimide (PI)] and the like can be used.

Of these, polyester-based resins and polyamide-based resins are preferable in terms of physical characteristics, processability, handleability, and the like.

Further, the blend of the thermoplastic resin and the elastomer (thermoplastic elastomer composition) that can form the film 2 has a structure in which the elastomer is dispersed as a discontinuous phase in the matrix of the thermoplastic resin. By adopting such a structure, it is possible to obtain a molding processability equivalent to that of a thermoplastic resin. Of the thermoplastic resins and elastomers constituting the thermoplastic elastomer composition, the above-mentioned thermoplastic resins can be used. Examples of the elastomer constituting the thermoplastic elastomer composition include diene rubber and its hydrogenated product [for example, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), and butadiene. Rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydride NBR, hydride SBR], olefinic rubber [eg, ethylene propylene rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (eg, ethylene propylene rubber (EPDM, EPM)) M-EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene-based monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [for example, Br-IIR, CI-IIR, brominated isobutylene- p-Methylstyrene Elastomer (BIMS), Chloroprene Rubber (CR), Hydrin Rubber (CHR), Chlorosulfonated Polyethylene Rubber (CSM), Chlorinated Polyethylene Rubber (CM), Maleic Acid Modified Chlorinated Polyethylene Rubber (M-CM) )], Silicon rubber [for example, methyl vinyl silicon rubber, dimethyl silicon rubber, methylphenyl vinyl silicon rubber], sulfur-containing rubber [for example, polysulfide rubber], fluororubber [for example, vinylidene fluoride-based rubber, fluorovinyl ether-based rubber, Tetrafluoroethylene-propylene-based rubber, fluorine-containing silicon-based rubber, fluorine-containing phosphazene-based rubber], thermoplastic elastomers [for example, styrene-based elastomers, olefin-based elastomers, ester-based elastomers, urethane-based elastomers, boliamide-based elastomers] and the like are preferable. Can be used.

In particular, when a plurality of elastomers are blended, 50% by weight or more of them are butyl halide or brominated isobutylene paramethylstyrene copolymer rubber or maleic anhydride-modified ethylene α-olefin copolymer rubber. It is preferable in that it can be increased to be flexible and highly durable from low temperature to high temperature.

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 /. Excellent durability can be obtained by using any of 10 copolymers, nylon 4/6 copolymers, nylon 6/66/12 copolymers, aromatic nylons, and ethylene / vinyl alcohol copolymers. It is possible and preferable.

Further, when preparing a thermoplastic elastomer composition by combining the above-mentioned specific thermoplastic resin and elastomer, if the compatibility between the two is insufficient, they are compatible with each other by using an appropriate compatibilizer as the third component. be able to. By mixing the compatibilizer with the blend system of the thermoplastic resin and the elastomer, the interfacial tension between the thermoplastic resin and the elastomer is reduced, and as a result, the particle size of the elastomer forming the dispersed phase becomes finer. Therefore, the characteristics of both components will be expressed more effectively. Such compatibilizers generally include copolymers having the structure of both or one of the thermoplastic resins and elastomers, or epoxy, carbonyl, halogen, and amino groups that can react with the thermoplastic resin or elastomer. , The structure of the copolymer having an oxazoline group, a hydroxyl group and the like can be taken. These may be selected according to the type of thermoplastic resin and elastomer to be blended, but the commonly used ones are styrene / ethylene / butylene block copolymers (SEBS) and their maleic acid modified products, EPDM, EPM, etc. Examples thereof include EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid modified product, styrene / maleic acid copolymer, reactive phenoxine and the like. The blending amount of the compatibilizer 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 (total of the thermoplastic resin and the elastomer).

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

In the present invention, the thermoplastic resin or the thermoplastic elastomer composition obtained by blending the thermoplastic resin and the elastomer is, for example, other than the compatibilizer described above, as long as the properties required for forming the film 2 are not impaired. Also, other polymers can be mixed. The purpose of mixing other polymers is to improve the moldability of the material, to improve heat resistance, to reduce costs, etc., and the materials used for this are, for example, polyethylene (PE) and polypropylene ( PP), polystyrene (PS), ABS, SBS, polycarbonate (PC) and the like can be exemplified.

In addition, fillers (calcium carbonate, titanium oxide, alumina, etc.) generally blended in polymer formulations, 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 required properties of the film 2 are not impaired.

The elastomer blended with the thermoplastic resin can also be dynamically vulcanized when mixed 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.

The fact that the elastomer in the thermoplastic resin composition is dynamically vulcanized in this way means that the obtained thermoplastic elastomer composition contains the vulcanized elastomer, and thus resists deformation from the outside. It is preferable because it has a force (elasticity) and can increase the effect of the present invention.

As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specifically, examples of the sulfur-based vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorphophosphorindisulfide, and alkylphenol disulfide, and examples thereof include 0.5 to 0.5. About 4 phr (in the present specification, "phr" means a part by weight per 100 parts by weight of the elastomer component. The same shall apply hereinafter) can be used.

Examples of the organic peroxide-based vulcanizing agent include benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, and 2,5-dimethyl-2,5-di (t-butyl peroxide). Oxy) hexane, 2,5-dimethylhexane-2,5-di (peroxylbenzoate) and the like are exemplified, and for example, about 1 to 20 phr can be used.

Further, as the phenol resin-based vulcanizing agent, a bromine of an alkylphenol resin, a mixed cross-linking system containing a halogen donor such as tin chloride or chloroprene and an alkylphenol resin, or the like can be exemplified, and for example, about 1 to 20 phr should be used. Can be done.

Others include zinc flower (about 5 phr), magnesium oxide (about 4 phr), litharge (about 10 to 20 phr), p-quinone dioxime, p-dibenzoylquinone dioxime, tetrachloro-p-benzoquinone, poly-p-. Examples thereof include dinitrosobenzene (about 2 to 10 phr) and methylene dianiline (about 0.2 to 10 phr).

Further, a vulcanization accelerator may be added as needed. As the vulcanization accelerator, general vulcanization accelerators such as aldehyde / ammonia type, guanidine type, thiazole type, sulfenamide type, thiuram type, dithioate type and thiourea type can be used, for example, from 0.5 to 0.5. About 2 phr can be used.

The rubber material constituting the rubber composition 3 includes diene rubber such as natural rubber, isoprene rubber, epoxidized natural rubber, styrene butadiene rubber, and hydride styrene butadiene rubber, ethylene propylene rubber, and maleic acid-modified ethylene propylene. Olefin-based rubber such as rubber can be preferably used.

Then, the film 2 may be laminated with an adhesive layer interposed therebetween in order to enhance the adhesiveness with the adjacent rubber composition 3. Examples of the polymer constituting the adhesive layer include acrylate copolymers having a molecular weight of 1 million or more, preferably 3 million or more, such as ultrahigh molecular weight polyethylene, ethylene ethyl acrylate copolymer, ethylene methyl acrylate resin, and ethylene acrylate copolymer. And their maleic anhydride adduct, polypropylene and its maleic acid modified product, ethylene propylene copolymer and its maleic acid modified product, thermoplastic resin and its anhydrous maleic acid modified product, styrene-butadiene-styrene copolymer, styrene. -Ethethylene-butadiene-styrene copolymer, fluorine-based thermoplastic resin, polyester-based thermoplastic resin and the like are preferably used.

In the above-described embodiment, the pneumatic tire in which the reinforcing layer is the carcass layer 14 has been described, but the present invention can also be applied to a pneumatic tire in which the reinforcing layer is a belt layer or a side reinforcing layer. In particular, when the reinforcing layer is the carcass layer 14 and the film 2 constituting the laminated body 1 is arranged on the inner surface side of the tire with respect to the carcass layer 14, the occurrence of cracks is suppressed and the durability is effective. Can be improved.

A film of a thermoplastic elastomer composition containing a blend of a thermoplastic resin and an elastomer with a tire size of 195 / 65R15 (for passenger cars) and 275 / 70R22.5 (for heavy loads) and rubber laminated on both sides of the film. It is provided with a laminate made of a composition and a one-layer reinforcing layer arranged adjacent to the laminate and composed of a steel cord, and the end portions of the laminate in the tire circumferential direction are overlapped with each other to form a lap splice. In a pneumatic tire in which a portion is formed and an interlayer rubber layer made of a rubber composition is interposed between the layers of the film in the lap splice portion, the type of tire, the lap length L, the average thickness Gf of the film, and the oxygen permeation of the film. Coefficient Pf, average thickness Gg of the interlayer rubber layer, oxygen permeation coefficient Pg of the interlayer rubber layer, distance Dc in the film thickness direction from the end of the film to the steel cord of the reinforcing layer, Gf × Pg × Gg / (Pf ×) The tires of Comparative Examples 1 to 3 and Examples 1 to 5 in which Dc) was different as shown in Table 1 were produced.

In each test tire, it was common that the reinforcing layer arranged adjacent to the laminated body was a carcass layer. Further, in the tires of Comparative Examples 1 and 3 and Example 3 (oxygen permeability coefficient Pf = 10 in Table 1), the films were nylon 6/66 copolymer (N6 / 66) and brominated isobutylene-p-methyl. It is a thermoplastic elastomer composition containing a styrene copolymer (BIMS) at a weight ratio of 50/50, and is a film in the tires of Comparative Example 2 and Examples 1 and 5 (oxygen permeability coefficient Pf = 5 in Table 1). Is a thermoplastic elastomer composition containing N6 / 66 and BIMS in a weight ratio of 75/25, and in the tires of Examples 2 and 4 (oxygen permeability coefficient Pf = 20 in Table 1), the film is N6 / 66 and BIMS. It is a thermoplastic elastomer composition containing 30/70 by weight. In each test tire, it was common that the rubber composition was a rubber composition containing natural rubber and styrene-butadiene rubber as main components.

The durability of these test tires was evaluated by the following test method, and the results are also shown in Table 1.

durability:
Assemble each test tire to either rim size 15 x 6JJ (for passenger cars) or rim size 22.5 x 7.50 (for heavy loads), and air so that the tire internal pressure is 240 kPa (for passenger cars) or 900 kPa (for heavy loads). Was filled. This tire was placed on an indoor drum tester, loaded with a load of 120% of the maximum load capacity specified by JATTA, and ran for 20,000 km at a speed of 80 km / h (for passenger cars) or 50 km / h (for heavy loads). After that, the steel cord constituting the reinforcing layer was visually observed to confirm the occurrence of separation, and if it occurred, the length of separation [mm] was measured.

As can be seen from Table 1, in the tires of Examples 1 to 5, the lap length L in the tire circumferential direction of the laminated body is set to be longer than the length obtained from the formula (1) specified in the present invention. It was possible to prevent the occurrence of separation in the steel cord constituting the reinforcing layer, and the durability was improved as compared with the tires of Comparative Examples 1 to 3.

1 Laminate 2 Film 3 Rubber composition 3A Interlayer rubber layer 4 Wrap splice part 10 Inner liner layer 11 Tread part 12 Side wall part 13 Bead part 14 Carcus layer 14A Steel cord 15 Belt layer 16 Bead core L Wrap length

Claims (7)

A laminate composed of a thermoplastic resin or a film of a thermoplastic elastomer composition containing a blend of a thermoplastic resin and an elastomer and a rubber composition laminated on at least one side of the film, and adjacent to the laminate. The laminated body is provided with at least one reinforcing layer composed of steel cords, and the ends of the laminated body in the tire circumferential direction are overlapped with each other at at least one position on the tire circumference to form a lap splice portion. In a pneumatic tire in which an interlayer rubber layer made of the rubber composition is interposed between layers of the film in the lap splice portion, the lap length L of the laminate in the tire circumferential direction in the lap splice portion is the following formula (1). ) Satisfies
It is characterized in that there is no lap splice portion in which the ends of other tire components in the tire circumferential direction are overlapped with each other in a region of 10 mm on both sides of the lap splice portion in the tire circumferential direction including the lap splice. Pneumatic tires.
L ≧ Gf × Pg × Gg / (Pf × Dc) (1)
However, Gf: the average thickness [mm] of the film other than the wrap splice portion.
Gg: Average thickness [mm] of the interlayer rubber layer in the wrap splice portion
Pf: Oxygen permeability coefficient of the film [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Pg: Oxygen permeability coefficient of the interlayer rubber layer [10 ^-3 · mm · cc / (m ² · day · mmHg)]
Dc: Distance [mm] in the film thickness direction from the end of the film to the steel cord constituting the reinforcing layer. The film obtained by dividing the oxygen permeability coefficient Pf [10 ^-3 · mm · cc / (m ² · day · mmHg)] of the film by the average thickness Gf [mm] of the film other than the wrap splice portion. [10 ^-3 · cc / (m ² · day · mmHg)] and the maximum air pressure P [kPa] of the tire satisfy the relationship of Pf / Gf ≦ 50,000 / P. The pneumatic tire according to 1. The invention according to claim 1 or 2, wherein the oxygen permeability coefficient Pf at a temperature of 23 ° C. and a humidity of 65% of the film is 20 [10 ^-3 · mm · cc / (m ² · day · mmHg)] or less. Pneumatic tires. The pneumatic tire according to any one of claims 1 to 3, wherein the average thickness Gf of the film other than the wrap splice portion is 0.03 mm to 0.50 mm. Claims 1 to 4 are characterized in that the oxygen permeability coefficient Pg of the interlayer rubber layer at a temperature of 23 ° C. and a humidity of 65% is 2000 [10 ^-3 · mm · cc / (m ² · day · mmHg)] or less. Pneumatic tires listed in any of. The pneumatic tire according to any one of claims 1 to 5, wherein the average thickness Gg of the interlayer rubber layer in the lap splice portion is 0.10 mm to 1.00 mm. The pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing layer is a carcass layer, and the film is arranged on the inner surface side of the tire with respect to the carcass layer.

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