JP2010013647A - Sidewall-protective film and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sidewall-protective film using a polymer composition, which can simultaneously improve durability, adhesion to an adjacent rubber and processability while maintaining air-permeation-resistance; and to provide a pneumatic tire. <P>SOLUTION: The sidewall-protective film includes a polymer mixture containing 99-60 mass% of a styrene-isobutyrene-styrene triblock copolymer and 1-40 mass% of a polyamide-based polymer containing a polyamide in a molecule chain and having a Shore D hardness of 70 or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sidewall protective film and a pneumatic tire using a polymer composition having excellent durability and air permeation resistance and excellent adhesion to adjacent rubber.

  In recent years, tires have been made lighter due to the strong social demand for low fuel consumption of vehicles, and among the tire members, the amount of air leakage from the inside of the pneumatic tire to the outside is arranged inside the tire. Even in an inner liner having a function of improving the air permeation resistance by reducing (air permeation amount), weight reduction and the like have been performed.

  Currently, the rubber composition for an inner liner uses a butyl rubber containing 70 to 100% by mass of butyl rubber and 30 to 0% by mass of natural rubber to improve the air permeation resistance of the tire. . In addition to butylene, the butyl rubber contains about 1% by mass of isoprene, which, together with sulfur, vulcanization accelerator, and zinc white, enables co-crosslinking with adjacent rubber. The butyl rubber usually requires a thickness of about 0.6 to 1.0 mm for passenger car tires and about 1.0 to 2.0 mm for truck and bus tires. Therefore, there has been proposed a polymer that is more excellent in air permeation resistance than butyl rubber and can make the inner liner layer thinner.

  In Patent Document 1, as a pneumatic tire capable of simultaneously suppressing air pressure reduction, improving durability, and improving fuel consumption, 100 parts by mass of a rubber component made of natural rubber and / or synthetic rubber is used. , The following general formula (I),

  (In the formula, m and n are each independently 1 to 100, and x is 1 to 1000.) The ethylene-vinyl alcohol copolymer represented by at least is contained in the range of 15 to 30 parts by mass. There has been proposed a pneumatic tire obtained by using the rubber composition for an inner liner as an inner liner layer. However, in the technique of Patent Document 1, the thickness of the rubber sheet using the rubber composition is 1 mm, and there is room for improvement in terms of weight reduction of the tire.

  Patent Document 2 proposes a pneumatic tire in which an inner liner layer is formed using nylon having a low air permeability and adhesion with a tire inner surface or a carcass layer, which is a rubber composition, can be improved. . However, in the technique of Patent Document 2, in order to form a nylon film layer, after the nylon film is RFL-treated, it is necessary to bond a rubber paste made of a rubber composition, which causes a problem that the process becomes complicated. .

JP 2007-291256 A JP-A-9-165469

  The present invention solves the above-mentioned problems and protects sidewalls using a polymer composition capable of simultaneously improving durability, adhesion to adjacent rubber, and processability while maintaining air permeation resistance. The object is to provide a membrane and a pneumatic tire.

  The present invention relates to a sidewall comprising 99 to 60% by mass of a styrene-isobutylene-styrene triblock copolymer and a polymer mixture comprising 1 to 40% by mass of a polyamide-based polymer having a Shore D hardness of 70 or less and containing polyamide in the molecular chain. It is a protective film.

  In the sidewall protective film according to the present invention, the polymer mixture preferably contains 15 to 40% by mass of an ethylene-vinyl alcohol copolymer.

  In the side wall protective film according to the present invention, the polymer mixture preferably includes a styrene-isobutylene-styrene triblock copolymer in a range of 10 to 30% by mass of styrene.

  In the sidewall protective film according to the present invention, the polymer mixture is preferably a block copolymer in which a polyamide-based polymer is composed of a polyamide component and a polyether component.

  In the sidewall protective film according to the present invention, it is preferable that 5 to 40 parts by mass of filler is included with respect to 100 parts by mass of the polymer mixture.

  The sidewall protective film according to the present invention preferably contains 10 to 25 parts by mass of mica as a filler with respect to 100 parts by mass of the polymer mixture.

  In the sidewall protective film according to the present invention, 1 to 30 parts by mass of one or more selected from the group consisting of C5 petroleum resin, C9 petroleum resin and terpene resin may be included with respect to 100 parts by mass of the polymer mixture. preferable.

  The present invention is a pneumatic tire having a sidewall portion provided with the sidewall protective film.

  According to the present invention, by blending a specific amount of styrene-isobutylene-styrene triblock copolymer and polyamide polymer, a polymer having excellent durability and air permeation resistance and excellent adhesion to adjacent rubber. A sidewall protective film and a pneumatic tire using the composition can be provided.

  Furthermore, by adding a non-phenolic resin to the polymer composition, a sidewall protective film and a pneumatic tire excellent in processability can be provided.

  In addition, by bonding an insulation rubber to the polymer composition or applying a rubber paste, it is possible to further improve the adhesion and workability with the adjacent rubber.

It is a typical sectional view showing the right half of the pneumatic tire concerning the present invention. It is a typical sectional view showing the right half of the pneumatic tire concerning the present invention. 1 is a schematic cross-sectional view of an inner liner rubber-insulation rubber joined body and a carcass according to the present invention.

  The polymer mixture of the present invention comprises 99 to 60% by mass of a styrene-isobutylene-styrene triblock copolymer (hereinafter also referred to as SIBS), and a polyamide-based polymer 1 to 40 having a Shore D hardness of 70 or less and containing polyamide in the molecular chain. Including mass%.

  Due to the isobutylene moiety of SIBS, the polymer mixture has excellent air permeation resistance and durability. In addition, SIBS has excellent durability because its molecular structure other than aromatic is completely saturated, thereby preventing deterioration and hardening. On the other hand, due to the contribution from the polyamide portion of the polyamide-based polymer, the polymer mixture can be bonded to the unsaturated polymer, and the adhesion to the adjacent rubber is improved.

  Furthermore, in the present invention, when a polymer composition containing the polymer mixture is used for a pneumatic tire, in order to ensure air permeation resistance by including SIBS, for example, conventional air permeation resistance such as halogenated butyl rubber. It is possible to reduce the amount of use even when the high specific gravity halogenated rubber that has been used for imparting is used or not. As a result, the weight of the tire can be reduced, and the effect of improving fuel consumption can be obtained. Further, the halogenated rubber has a problem that the adhesion between the ply cord of the pneumatic tire and the rubber is deteriorated due to the halogen in the rubber. In the present invention, the amount of the halogenated rubber is used. Therefore, the durability of the pneumatic tire can be improved by improving the adhesion between the ply cord and the polymer composition.

<Styrene-isobutylene-styrene triblock copolymer>
In the polymer mixture of the present invention, the SIBS content is 99 to 60% by mass. When the SIBS content is 60% by mass or more, a polymer composition having excellent air permeation resistance and durability can be obtained. Moreover, it is preferable that this content shall be 95-80 mass% at the point from which air permeation resistance and durability become more favorable.

  The SIBS generally contains 10 to 40% by mass of styrene. The content of the styrene is preferably 10 to 30% by mass in terms of better air permeation resistance and durability.

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

  SIBS can be obtained by a general vinyl compound polymerization method, for example, a living cationic polymerization method.

  For example, JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible. By using isobutylene and other compounds as vinyl compounds, It is disclosed that a polyisobutylene-based block copolymer can be produced. In addition, methods for producing vinyl compound polymers by the living cationic polymerization method are disclosed in, for example, U.S. Pat. No. 4,946,899, U.S. Pat. No. 5,219,948, and JP-A-3-174403. Are listed.

  Since SIBS does not have double bonds other than aromatics in the molecule, it is more stable to ultraviolet rays than a polymer having double bonds in the molecule, such as polybutadiene, and is therefore weather resistant. Is good. Furthermore, although it has no double bond in the molecule and is a saturated rubber-like polymer, the refractive index (nD) at 20 ° C. of light with a wavelength of 589 nm is the Polymer Handbook (1989: Wiley). (Polymer Handbook, Willy, 1989)) is 1.506. This is significantly higher than other saturated rubbery polymers such as ethylene-butene copolymers.

<Polyamide polymer>
In the polymer mixture of the present invention, the content of the polyamide-based polymer is 1 to 40% by mass. When the content of the polyamide-based polymer is 40% by mass or less, a polymer mixture in which durability and adhesiveness are compatible can be obtained. Moreover, it is preferable that this content shall be 3-20 mass% at the point which can ensure durability and adhesiveness and can mix | blend more SIBS and ethylene-vinyl alcohol copolymer which are excellent in air permeation resistance.

  The polyamide polymer of the present invention is preferably a polyamide polymer having a Shore D hardness of 70 or less. If the Shore D hardness exceeds 70, it is not preferable because the cracking property at the time of bending and moving of the tire is inferior. The Shore D hardness is preferably in the range of 15 to 70, more preferably in the range of 18 to 70, more preferably in the range of 20 to 70, and particularly preferably in the range of 25 to 70.

  The polyamide polymer of the present invention preferably contains 50% by mass or more of the following polyetheramide elastomer (X).

Polyetheramide elastomer (X):
A block copolymer comprising a polyamide component and a polyether component obtained by polymerizing a triblock polyetherdiamine compound (A) represented by the following formula (II), a polyamide-forming monomer (B), and a dicarboxylic acid compound (C). It is a polymer.

(In the formula, a and b are 1 to 20, and c is 4 to 50.)
The polyamide-forming monomer (B) is preferably represented by the following formula (III) and / or the following formula (IV).

(In the formula, R ¹ represents a linking group containing a hydrocarbon chain.)

(In the formula, R ² represents a linking group containing a hydrocarbon chain.)
The dicarboxylic acid compound (C) is preferably represented by the following formula (V) and / or an aliphatic dicarboxylic acid compound and / or an alicyclic dicarboxylic acid compound.

(In the formula, R ³ represents a linking group containing a hydrocarbon chain, and y represents 0 or 1.)
When the polyamide-based polymer is a polyamide-based polymer having a hard segment derived from a polyamide component and a soft segment derived from a polyether component, the crystallinity is lowered, and therefore, the elongation at break EB is high, and from a low temperature to a high temperature region. A polyamide-based polymer exhibiting flexibility can be obtained.

  In addition, since the polyamide-based polymer has improved fluidity at the tire vulcanization temperature (140 to 180 ° C.) and wettability with the uneven surface, it can exhibit an excellent effect in adhesion to the adjacent rubber.

  A known polyamide polymer can be used as the polyamide polymer in the present invention. As the polyamide-based polymer, at least one selected from a polyamide block composed of at least one aliphatic nylon selected from nylon 6, nylon 66, nylon 11, and nylon 12, and polyoxyethylene, polyoxypropylene, and polyoxybutylene. An elastomer composed of a polyether block of

  The method for producing the polyamide polymer is not particularly limited, and methods disclosed in JP-A-56-65026, JP-A-55-133424, JP-A-63-95251 and the like can be used. it can.

<Polymer mixture>
The polymer mixture of the present invention may contain another polymer or resin in addition to SIBS and a polyamide-based polymer having a Shore D hardness of 70 or less containing polyamide in the molecular chain.

  The polymer mixture of the present invention preferably contains an ethylene-vinyl alcohol copolymer within a range of 15 to 40% by mass. When the content of the ethylene-vinyl alcohol copolymer in the polymer mixture is 15% by mass or more, the gas barrier property of the polymer composition is ensured. Further, when the content is 40% by mass or less, kneadability at the time of producing the polymer composition is secured, and basic performance such as mechanical strength is secured in the inner liner layer of the tire. The content is preferably 20% by mass or more, and more preferably 25% by mass or more. Further, from the viewpoint of tire durability, the content is preferably 30% by mass or less.

  The ethylene-vinyl alcohol copolymer of the present invention has the following general formula (I):

(Wherein, m and n are each independently 1 to 100, and x is 1 to 1000), and is preferably an ethylene-vinyl alcohol copolymer.

  The ethylene-derived portion of the ethylene-vinyl alcohol copolymer imparts good compatibility with the polymer mixture, and the ethylene-vinyl alcohol copolymer can exist in a fine dispersion size in the polymer composition. On the other hand, the ethylene-vinyl alcohol copolymer has good gas barrier properties due to the contribution of vinyl alcohol-derived sites. That is, in the present invention, when the inner liner layer of the tire is thinned because the ethylene-vinyl alcohol copolymer excellent in gas barrier properties is dispersed in an island shape with a fine size in the polymer composition. However, good gas barrier properties are exhibited. As a result, the weight of the tire can be reduced, and the effect of improving fuel consumption can be obtained.

  In general formula (I), m and n are 1 or more in order to constitute an ethylene-vinyl alcohol copolymer. On the other hand, when m and n are each 100 or less, an ethylene-vinyl alcohol copolymer having compatibility with the polymer mixture and gas barrier properties can be obtained. In view of better compatibility with the polymer mixture, m is preferably 5 or more. Moreover, it is preferable that n is further set to 5 or more from the viewpoint of better gas barrier properties. On the other hand, m is preferably 95 or less, more preferably 80 or less, from the viewpoint that it is difficult to impair the gas barrier property due to the vinyl alcohol-derived site. Further, n is preferably 95 or less, and more preferably 80 or less, from the viewpoint that it is difficult to impair the expression of good compatibility with the polymer mixture due to the ethylene-derived site.

  In the general formula (I), x is 1 or more in order to constitute an ethylene-vinyl alcohol copolymer. On the other hand, when x is 1000 or less, kneadability at the time of producing the polymer composition is ensured, and a polymer composition in which the ethylene-vinyl alcohol copolymer is uniformly dispersed is obtained. X is preferably set to 10 or more in view of good compatibility with the polymer mixture and gas barrier properties, and x is further 500 or less, and further 100 in view of good kneadability. The following is preferable.

  The ethylene-vinyl alcohol copolymer represented by the general formula (I) may be contained in the polymer composition in the form of a copolymer with other components. In this case, the ethylene-vinyl alcohol copolymer The content of the polymer means the content of the structural portion represented by the general formula (I).

  The molecular structure of the ethylene-vinyl alcohol copolymer can be confirmed by, for example, an infrared absorption spectrum (IR) or a nuclear magnetic resonance spectrum (NMR).

  The polymer composition has the following general formula (VI):

(Wherein R is an alkyl group, p and q are each independently 1 to 100, and z is 1 to 5). The compatibilizing agent has an effect of further enhancing the compatibility between the polymer mixture and the ethylene-vinyl alcohol copolymer in the polymer composition. When p and q in the general formula (VI) are each 1 or more, the action as a compatibilizer is good, and when p and q are each 100 or less, the compatibilizer is dispersed in the polymer mixture. Good properties. p is preferably 5 or more, more preferably 95 or less, and further preferably 80 or less. q is preferably 5 or more, more preferably 95 or less, and further preferably 80 or less.

  Z in the general formula (VI) is 1 or more in order to constitute a block copolymer. Further, z is preferably 5 or less from the viewpoint that the dispersibility of the compatibilizing agent in the polymer composition is good. z is preferably 2 or more, and more preferably 4 or less.

  The content of the compatibilizer represented by the general formula (VI) in the polymer mixture is preferably in the range of 0.1 to 4.8% by mass. When the content is 0.1% by mass or more, the effect as a compatibilizing agent is expressed well, and when it is 4.8% by mass or less, basic performance such as mechanical strength is reduced in the inner liner layer of the tire. This can be prevented well. The content is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and further preferably 1.5% by mass or more, and is further 4.3% by mass or less, and further 3.8% by mass. % Or less, and preferably 3.4 mass% or less.

  The compatibilizing agent represented by the general formula (VI) may be contained in the polymer composition in a state of being a copolymer with other components. In this case, what is the content of the compatibilizing agent? Means the content of the structural moiety represented by the general formula (VI).

  In addition to SIBS and polyamide polymer, the polymer mixture of the present invention includes nylon, PET, chlorobutyl rubber, natural rubber, ethylene propylene-diene terpolymer (EPDM), styrene butadiene rubber (SBR), butadiene rubber, isoprene. Rubber, butyl rubber, halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like can be blended.

<Polymer composition>
The Shore A hardness of the polymer composition comprising the polyamide polymer and SIBS can be in the range of 25-65. When the hardness is 25 or more, the mechanical strength of the polymer composition for the inner liner is good, and when it is 65 or less, it is possible to prevent a decrease in durability caused by the polymer composition for the inner liner becoming too hard. The hardness is further preferably 40 or more, more preferably 42 or more, and further 45 or more, and further preferably 62 or less, more preferably 58 or less. The hardness is a value measured according to JIS K 6253.

  The specific gravity of the polymer composition for an inner liner used in the present invention can be 1.70 or less. When the specific gravity is 1.70 or less, the effect of improving the fuel consumption by reducing the weight of the tire is good. The specific gravity is preferably set to 1.40 or less and further 1.20 or less.

<Softener>
In the present invention, the polymer composition for the inner liner may contain a non-phenolic resin. In this case, the air permeation resistance, rolling resistance and processability of the polymer composition for an inner liner are further improved. The content of the non-phenolic resin is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the polymer mixture.

  The non-phenolic resin is close to the isobutylene and the SP value (Solubility Parameter), and is a compatible C5 petroleum resin (C5 petroleum resin is an olefin in the C5 fraction obtained by naphtha decomposition) , Aliphatic petroleum resins mainly composed of diolefins), C9 petroleum resins (C9 petroleum resins are aromatic petroleum resins mainly composed of olefins in C9 fraction obtained by naphtha cracking) It is preferable to use one or more selected from terpene resins, and it is more preferable to use a C5 petroleum resin. For example, Mitsui Petrochemical's Highlett G-100, Maruzen Petroleum Marcaretz T-100AS, Tonex's Escorez 1102, C9 Petroleum resin as Tosoh Petocol XL, Yashara Chemical's YS Resin PX300N, YS resin PX1150N, etc. can be mentioned.

  When a softening agent close to the SP value of the polymer is used, it can be mixed well with the polymer, has good vulcanization adhesiveness with the adjacent member, and can properly exhibit normal temperature adhesion during processing.

  When a C5 petroleum resin is used as the softening agent, the content is 10-30 parts by mass with respect to 100 parts by mass of the polymer mixture in order to improve air permeability, complex elastic modulus, adhesiveness and processability. More preferably, it is within the range. The amount of 10 parts by mass or more is preferable because the adhesive force with an adjacent member is improved and the film can be prevented from being peeled off naturally during molding. Further, if it is 30 parts by mass or less, tan δ is good, and it is preferable because over-adhesion (wrinkles, holes) during processing can be prevented.

<Filler>
In the present invention, the polymer composition for the inner liner may further contain at least one filler composed of carbon black, talc, clay, mica, calcium carbonate, and the like. In this case, the resistance and mechanical strength at break of the polymer composition for an inner liner are improved, and in particular, when a flat filler such as mica is included, the gas barrier property is further improved. It is preferable that content of this filler shall be in the range of 5-40 mass parts with respect to 100 mass parts of polymer mixtures. When the content is 5 parts by mass or more, the mechanical strength of the polymer composition for the inner liner is increased, so that the durability and steering performance of the tire are improved. When the content is 40 parts by mass or less, the rubber composition for the inner liner Good workability during production. The content is more preferably in the range of 10 to 30 parts by mass.

  In the present invention, it is more preferable that mica is contained as the filler in an amount of 10 to 25 parts by mass with respect to 100 parts by mass of the polymer mixture from the viewpoint of improving the air blocking effect.

  The mica (mica) is preferably at least one selected from the group consisting of mascobite (muscovite), phlogopite (phlogopite), and biotite (biotite). Among these, it is preferable to use a phlogopite because the flatness is higher than other mica and the air blocking effect is excellent.

  The average particle diameter of mica is 40 μm or more, preferably 45 μm or more. If the average particle diameter is less than 40 μm, the effect of improving air retention tends to be insufficient. The average particle diameter of mica is 100 μm or less, preferably 70 μm or less. When the average particle diameter exceeds 100 μm, mica becomes large and becomes a starting point of cracking, and the inner liner tends to crack due to bending fatigue.

  Examples of the resin that covers the surface of mica include urethane resin, acrylic resin, epoxy resin, nylon resin, and polyester resin. Of these, urethane resins, acrylic resins, and epoxy resins are preferred because they have a relatively high compatibility with rubber. As a coating method, a method is used in which a resin is melted, mica is put therein, stirred, then solidified, and pulverized.

  The aspect ratio (flatness) of mica is 50 or more, preferably 55 or more. If the aspect ratio is less than 50, a sufficient effect of improving air retention cannot be obtained. Further, the aspect ratio of mica is preferably 100 or less, and more preferably 70 or less. When the aspect ratio exceeds 100, the strength of the mica is reduced, and the mica is cracked. Here, the aspect ratio refers to the ratio of the major axis to the thickness in mica.

  Mica can be obtained by a grinding method such as wet grinding or dry grinding. Wet pulverization produces a clean surface and has a slightly higher effect of improving air retention. Also, dry pulverization has the respective characteristics that the manufacturing process is simple and the cost is low, and it is better to use them depending on the case.

  The mica content is 10 parts by mass or more, preferably 15 parts by mass or more with respect to 100 parts by mass of the polymer mixture. If the mica content is less than 10 parts by mass, sufficient air retention, heat generation and crack growth resistance of the inner liner cannot be obtained. The mica content is 25 parts by mass or less, preferably 20 parts by mass or less, with respect to 100 parts by mass of the rubber component. When the content of mica exceeds 25 parts by mass, the tear strength of the rubber composition decreases, and cracks are likely to occur.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black used as carbon black and / or silica is 2 from the viewpoint that sufficient reinforcing property is obtained and crack growth resistance is excellent.
0 m ² / g or more is preferable, and 25 m ² / g or more is more preferable. Also, N ₂ SA of carbon black is suppressed hardness of the polymer composition, from the viewpoint of excellent low heat build-up is preferably 70m ² / g or less, 60 m ² / g and more preferably less, 40 m ² / less is more preferable.

  Examples of the silica used as carbon black and / or silica include those adjusted by a wet method and those adjusted by a dry method, but are not particularly limited.

From the point that the nitrogen adsorption specific surface area (N ₂ SA) of silica is excellent in reinforcement and breakability,
80 m ² / g or more is preferable, and 100 m ² / g or more is preferable. The N ₂ SA of the silica is suppressed the hardness of the polymer composition, from the viewpoint of excellent low heat build-up, preferably 200 meters ² / g or less, 180 m ² / g and more preferably less, still is 150 meters ² / g or less preferable.

  When silica is used, the content of the silica is preferably 30 parts by mass or less with respect to 100 parts by mass of the polymer mixture. If it exceeds 30 parts by mass, the silica may self-aggregate.

  Furthermore, the polymer composition for an inner liner of the present invention can reduce the polymer component, reinforce the polymer composition, and reduce costs, so that calcium carbonate, Austin black, talc, It may contain clay, calcium carbonate and the like. Among them, it is preferable to contain talc or clay whose particle size does not become a nucleus of crack growth and does not reaggregate with good dispersibility.

  When blended with low molecular weight liquid oil such as process oil or paraffin oil as a softening agent, when processed as a film, the thin film is placed under high temperature conditions (around 200 ° C), so that the oil volatilizes and functions as an adhesive. There is a tendency that is difficult to be exhibited.

<Other ingredients>
In the polymer composition for an inner liner used in the present invention, the following components blended in other ordinary tire polymer compositions can be appropriately blended.

  As plasticizers, for example, DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP (phthalate) Diisodecyl acid), BBP (butyl benzyl phthalate), DLP (dilauryl phthalate), DCHP (dicyclohexyl phthalate) and the like may be blended.

<Preparation of polymer composition>
The polymer composition of the present invention is produced by injection processing. That is, a polymer mixture according to a predetermined compounding prescription is put into a rotary rotor installed in an injection press, and after blending polymer components in the rotary rotor, pressurizing and injection molding, The polymer composition can be adjusted.

  The injection molding is preferably performed using a 13 cm × 13 cm × 2 mm (thickness) mold under the conditions of a mold head pressure of 100 Kf, a head temperature of 200 ° C., an injection speed of 80 mm / second, and a rotor rotation speed of 100 rpm.

  When the filler is added to the polymer mixture of the present invention, the degree of dispersion may be insufficient in the rotary rotor installed in the injection press. Therefore, the polymer mixture and the filler are preliminarily used as a kneader, roll, Banbury mixer, etc. It is preferable to mix. The preliminary mixing is preferably performed with a temperature control roll or a temperature control Banbury (temperature condition: 130 ° C. to 180 ° C.).

  The polymer composition of the present invention can also be produced by a T-die film extruder after being pelletized by a twin-screw extruder.

<Inner liner rubber-insulation rubber assembly>
When the polymer mixture or polymer composition according to the present invention is used for an inner liner of a tire, it is preferable to use an inner liner rubber-insulation rubber joined body.

  The inner liner rubber-insulation rubber assembly will be described with reference to FIG. The insulation rubber 11 is interposed between the inner liner rubber 9b and the carcass 6 so as to increase the adhesive force between them and prevent delamination, and the inner liner 9 caused by the rubber flow during vulcanization molding The contact with the carcass cord 6a is suppressed. Therefore, it is important that the insulation rubber 11 is excellent in adhesiveness. For example, an NR rubber in which 50 parts by mass or more of natural rubber (NR) is blended in 100 parts by mass of the rubber component is used. it can. Note that isoprene rubber (IR) or butadiene rubber (BR) can be suitably used as the remaining rubber.

  The method for producing the inner liner rubber-insulation rubber joined body is as follows, for example. First, a polymer mixture or a polymer composition is pelletized with a twin screw extruder, and then a polymer film is produced with a T-die film extruder. The polymer film is bonded to an insulation rubber rolled at a temperature in a calendar process of 70 ° C. to 130 ° C. to obtain an inner liner rubber-insulation rubber joined body.

  The temperature of the calendar process of the insulation rubber is preferably 70 ° C to 130 ° C. When the temperature is less than 70 ° C., sufficient adhesion performance between the inner liner rubber and the insulation rubber cannot be obtained. On the other hand, when the temperature exceeds 130 ° C., the insulation rubber has started a vulcanization reaction, and sufficient adhesion performance between the inner liner rubber and the insulation rubber cannot be obtained.

<Inner liner rubber with rubber paste>
When the polymer mixture or polymer composition according to the present invention is used for an inner liner of a tire, it is preferable to use a rubber paste-coated inner liner rubber.

  For example, a method for producing the rubber glue coated inner liner rubber is as follows. First, a polymer mixture or a polymer composition is pelletized with a twin screw extruder, and then a polymer film is produced with a T-die film extruder. A rubber paste having a rubber composition concentration of 5 to 20% by weight is applied to the polymer film to obtain a rubber paste-coated inner liner rubber.

  As the rubber paste, those usually used for pneumatic tires can be used. For example, a rubber composition containing a diene rubber containing 70% by mass or more of natural rubber is dissolved in an organic salt having a low polarity such as toluene, N-hexane, or naphtha. In addition, sulfur, carbon, oil Resin that is a tackifier, anti-aging agent, stearic acid, zinc white, vulcanization accelerator, vulcanization retarder, and the like are contained in an amount equivalent to the rubber compounding of the carcass layer in parts by weight.

  The content of the rubber composition in the rubber paste is preferably 5 to 20% by weight. When the content is less than 5% by weight, the tackiness is inferior. Moreover, when this content exceeds 30 weight%, it will be difficult to apply | coat uniformly and it will be inferior to adhesiveness.

  As a method for applying the rubber paste, a conventionally known method can be used. For example, a method of applying with a spray is preferable.

<Pneumatic tire>
The pneumatic tire of the present invention is produced by an ordinary method using the polymer mixture or polymer composition of the present invention as an inner liner. The inner liner layer is obtained by extruding a blended component of the polymer mixture or polymer composition into a sheet (film shape) with a temperature control roll (temperature condition: 130 ° C. to 160 ° C.), and another tire on a tire molding machine. Laminate together with the member to form an uncrosslinked tire. The pneumatic tire of the present invention can be produced by heating and pressurizing the uncrosslinked tire in a vulcanizer.

  Furthermore, the pneumatic tire of this invention can join the insulation rubber rolled at the temperature of the calendar process of 70 to 130 degreeC to the inner liner which consists of a polymer mixture or polymer composition of this invention. By using the insulation rubber, the adhesion and workability between the inner liner layer and the carcass are improved, and a pneumatic tire having excellent durability can be obtained.

  Moreover, the pneumatic tire of this invention can apply | coat the rubber paste whose density | concentration of a rubber composition is 5 to 20 weight% to the inner liner which consists of a polymer mixture or polymer composition of this invention. By applying the rubber paste, it is possible to improve the molding adhesion performance at the time of tire production.

  In the present invention, it is preferable that the thickness of the inner liner layer measured at the maximum tire width position filled with the specified internal pressure is in the range of 0.1 to 1.5 mm. When the thickness of the inner liner layer is 0.1 mm or more, the effect of suppressing the decrease in air pressure is good, and when it is 1.5 mm or less, the effect of improving the fuel consumption by reducing the weight of the tire is good. The thickness of the inner liner layer is further preferably 0.15 mm or more, more preferably 0.2 mm or more, and further preferably 1.0 mm or less, further 0.6 mm or less.

  The present invention can be applied to various pneumatic tires for passenger cars, trucks / buses, heavy machinery and the like. FIG. 1 is a cross-sectional view showing the right half of a pneumatic tire according to the present invention. The pneumatic tire 1 has a tread portion 2, a sidewall portion 3, and a bead portion 4. Further, a bead core 5 is embedded in the bead portion 4. Further, a carcass 6 provided from one bead portion 4 to the other bead portion and folded back at both ends to lock the bead core 5 and a belt layer 7 composed of two plies outside the crown portion of the carcass 6 are arranged. Has been. An inner liner 9 extending from one bead portion 4 to the other bead portion 4 is disposed inside the carcass 6. Further, as shown in FIG. 3, the inner liner rubber 9 b can join the insulation rubber 11. Belt layer 7 is arranged so that two plies made of steel cord or cord such as aramid fiber intersect each other so that the cord is normally at an angle of 5 to 30 ° with respect to the tire circumferential direction. Is done. In the carcass, organic fiber cords such as polyester, nylon, and aramid are arranged at approximately 90 ° in the tire circumferential direction, and a bead extending in the sidewall direction from the upper end of the bead core 5 is located in a region surrounded by the carcass and the folded portion. An apex 8 is arranged.

  In addition, the polymer composition according to the present invention can be diverted to a protective film (vinia) (FIG. 2) for a sidewall portion of a tire or a gas transport hose. When the polymer composition according to the present invention is used as a protective film for a sidewall portion of a tire, the air barrier property of the tire is improved, and ozone and oxidative deterioration can be suppressed. For this reason, the anti-aging agent used for a side wall part can be decreased. The thickness of the sidewall portion is preferably in the range of 0.1 to 2.0 mm, and more preferably in the range of 0.2 mm to 0.6 mm.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Various chemicals used in Examples and Comparative Examples are as follows.
SIBS 102T: “Sibstar SIBSTAR 102 (Shore A hardness 25, styrene content 25%)” manufactured by Kaneka Corporation
SIBS 103T: “Sibstar SIBSTAR 103 (Shore A hardness 46, styrene content 30%)” manufactured by Kaneka Corporation
Polyamide polymer 1: “UBESTA XPA 9040 (Shore D hardness 40)” manufactured by Ube Industries, Ltd.
Polyamide-based polymer 2: “UBESTA XPA 9048 (Shore D hardness 48)” manufactured by Ube Industries, Ltd.
Ethylene-vinyl alcohol copolymer: “Eval E105” manufactured by Kuraray Co., Ltd.
Nylon: “Nylon 66” manufactured by Ube Industries
PET: “Polyethylene terephthalate PET” manufactured by Ube Industries
Chlorobutyl: “Exon Chlorobutyl 1068” manufactured by ExxonMobil
NR (natural rubber): TSR20
C5 Petroleum Resin: “Marcaretz T-100AS” manufactured by Maruzen Petrochemical Co., Ltd.
C9 Petroleum Resin: “Petocol XL” manufactured by Maruzen Petrochemical Co., Ltd.
Non-reactive phenolic resin: “SP1068” manufactured by NOF Corporation
Terpene resin 1: “YS Resin PX1150N” manufactured by Yasuhara Chemical Co., Ltd.
Terpene resin 2: “YS Resin PX300N” manufactured by Yasuhara Chemical Co., Ltd.
Paraffin oil: “Mineral oil” manufactured by Japan Energy
Carbon: “Seast V” manufactured by Tokai Carbon Co., Ltd. (N660, N2SA: 27 m ² / g)
Hard clay: “Hard clay crown” manufactured by Southeasten Clay (USA)
Talc: “Mistron HAR” manufactured by Luzenac (France) (average particle size 5.7 μm, average flatness 4.7)
Mica: “Mica (Mica) S-200HG” manufactured by Lebco (Frogobite, average particle size 50 μm, aspect ratio 55)
<Examples 1-19 and Comparative Examples 2-9, 11-14>
A polymer mixture and a softening agent according to the formulation shown in Table 2 and Table 3 are charged into a rotary rotor (100 rpm, length 1 M) of an injection press and blended, and then a 13 cm × 13 cm × 2 mm thick mold is applied to the press. And the polymers of Examples 1 to 19 and Comparative Examples 2 to 9 and 11 to 14 were extruded under the conditions of a mold head pressure of 100 kgf, a head temperature of 220 ° C., an injection speed of 80 mm / second, and a rotor rotation speed of 100 rpm. A sheet was produced.

  In Examples 6 to 8, 18 and 19, the polymer mixture and filler were mixed in advance using a kneader, roll (temperature control roll (temperature condition: 160 ° C.)), Banbury mixer and the like to prepare a master batch. These were weighed again and put into an injection press to prepare a polymer sheet. The conditions for the injection press are the same as described above.

  For pneumatic tires, polymer sheets having a thickness of 0.6 mm and 0.3 mm were prepared using the polymer mixture, respectively, applied to the inner liner portion of the tire, and press molded at 170 ° C. for 20 minutes. A 65R15 size tire was produced.

<Comparative Examples 1 and 10>
In Comparative Examples 1 and 10, with respect to 100 parts by mass of the rubber component shown in Table 3, as a rubber compound, 4 parts by mass of zinc white (“Ginseng R” manufactured by Toho Zinc Co., Ltd.), mineral oil (manufactured by Idemitsu Kosan Co., Ltd.) “Diana Process PA32”) 10 parts by mass, stearic acid (“Oji” manufactured by NOF Corporation) 1 part by mass, sulfur (“5% oil-treated powdered sulfur” manufactured by Tsurumi Chemical Co., Ltd.) 0.5 part by mass and acceleration 1.2 parts by mass of an agent (“Noxeller DM (di-2-benzothiazolyl disulfide)” manufactured by Ouchi Shinsei Chemical Co., Ltd.). In accordance with the above-mentioned blending prescription, using a Banbury mixer, chemicals other than zinc white, sulfur and vulcanization accelerator were added and kneaded for 4 minutes at a maximum temperature of 150 ° C. to obtain a kneaded product. Thereafter, zinc oxide, sulfur and a vulcanization accelerator are added to the obtained kneaded material, and kneaded for 4 minutes under a maximum temperature of 95 ° C. using a biaxial open roll to obtain an unvulcanized rubber composition. It was. The obtained unvulcanized rubber composition was rolled into a sheet shape with a mold, and press vulcanized for 12 minutes at 170 ° C., thereby producing vulcanized rubber sheets of Comparative Examples 1 and 10.

  In addition, rubber sheets having a thickness of 0.6 mm and 0.3 mm were prepared using the unvulcanized rubber composition, applied to the inner liner portion of the tire, respectively, and press-molded at 170 ° C. for 20 minutes, and 195 / 65R15 size A pneumatic tire was obtained.

<Adhesion test>
A carcass was prepared by pressurizing and heating a topping rubber sheet with an adjacent carcass cord having a thickness of 2 mm, the polymer sheet having a thickness of 1 mm or a vulcanized rubber sheet, and a reinforced canvas fabric at 150 ° C. for 20 minutes.

  Using the obtained carcass, a peel test was conducted in accordance with JIS K6256 “Vulcanized rubber and thermoplastic rubber—How to determine adhesion”, and evaluation was performed according to the following criteria.

<Air permeability test>
The air permeation amount of the polymer sheet and the vulcanized rubber sheet was measured according to ASTM D-1434-75M method.

<Tensile test>
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Tensile Properties”, a tensile test was conducted using a No. 3 dumbbell-shaped test piece composed of the polymer sheet and the vulcanized rubber sheet. The elongation at break EB (%) was measured.

<Hardness>
According to JIS K 6253 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Hardness”, the hardness of the polymer sheet and vulcanized rubber sheet was measured at 25 ° C. using a JIS-A hardness meter.

<Tangent loss (tan δ)>
In accordance with JIS K 5394, measurement was performed using a viscoelasticity measuring device at a temperature of 25 ° C. under conditions of an initial strain of 3%, a dynamic strain of ± 2%, and a frequency of 10 Hz.

<Processability>
The thread-like rubber after injection mixing and extrusion is rolled with a temperature control roll (150 ° C.) to produce a sheet having a thickness of 0.6 mm. At that time, the sheet flatness, presence / absence of perforations, and unevenness of the sheet edge were scored. The evaluation criteria are as follows.

  A: Sheet flat, no hole, straight sheet edge, adjacent rubber and proper processing tack.

B: Although not satisfying all of A, it has workability that can be actually used.
C: Actual use is impossible.

<Rolling resistance change rate>
Using a rolling resistance tester manufactured by Kobe Steel Co., Ltd., the manufactured 195 / 65R15 steel radial PC tire was assembled into a JIS standard rim 15 × 6JJ, under conditions of a load of 3.4 kN, an air pressure of 230 kPa, and a speed of 80 km / hour. The rolling resistance was measured by running at room temperature (38 ° C.). And according to the following calculation formula, the comparative example 1 was made into the reference | standard (+/- 0), and rolling resistance change rate (%) of each mixing | blending was displayed with the index | exponent. In addition, it shows that rolling resistance is reduced and is preferable, so that rolling resistance change rate is small, and specifically, it is preferable that it is negative.

(Rolling resistance change rate) = (Rolling resistance of each formulation-Rolling resistance of Comparative Example 1)
÷ (Rolling resistance of Comparative Example 1) × 100
<Static air pressure drop rate test>
A 195 / 65R15 steel radial PC tire is assembled to a JIS standard rim 15 × 6 JJ, an initial air pressure of 300 Kpa is enclosed, and left at room temperature for 90 days, and the rate of decrease in air pressure is calculated.

<Tire durability test>
A 195 / 65R15 steel radial PC tire is assembled to a JIS standard rim 15 × 6JJ and run at a speed of 80 km / h on a φ1707 mm drum at room temperature (38 ° C.) under test conditions of air pressure 150 kPa and load 6.96 KN. . Stop air leaks from cracks inside the inner liner, and if there are blisters on the side walls. Durability is determined by the superiority or inferiority of the distance until the swelling occurs. The evaluation criteria are as follows.

A: Distance> 30,000 km
B: 20,000 <distance ≦ 30,000 km
C: 10,000 ≦ distance ≦ 20,000 km
The results are shown in Table 2 and Table 3.

<Examples 20 and 21, Comparative Examples 15 to 19>
After the polymer mixture (Comparative Example 15 contains filler) according to the formulation shown in Table 4 was pelletized with a twin screw extruder (extrusion diameter: 50 mmφ, length: 1 m, temperature control: 220 ° C.), Polymer films of Examples 20 and 21 and Comparative Examples 15 to 19 were produced using a T-die film extruder (extrusion diameter: 80 mmφ, temperature control: 220 ° C., film gauge: 0.6 mm). The following tests were performed on the inner liner rubber-insulation rubber joined body obtained by joining the polymer film and the insulation rubber rolled at the temperature of the calendar process shown in Table 4.

  For pneumatic tires, polymer sheets with a thickness of 0.6 mm and 0.3 mm are prepared using the polymer film and the insulation rubber, and applied to the inner liner portion of the tire, respectively, and press molded at 170 ° C. for 20 minutes. A tire of 195 / 65R15 size was produced.

<Adhesion test>
A carcass is produced by pressurizing and heating a topping rubber sheet with an adjacent carcass cord with a thickness of 2 mm, the inner liner rubber-insulation rubber joined body with a thickness of 1 mm, and a reinforced canvas fabric at 150 ° C. for 20 minutes. Then, evaluation was performed according to the same conditions and criteria as in Example 1.

<Air permeability>
The inner liner rubber-insulation rubber joined body was measured under the same conditions as in Example 1.

<Tangent loss index>
With respect to the inner liner rubber-insulation rubber joined body, tangent loss (tan δ) was measured under the same conditions as in Example 10. Using Comparative Example 15 as a reference (100), the tangent loss of each formulation was displayed as an index.

(Tangent loss index) = (Tangent loss of each formulation / Tangent loss of Comparative Example 15) × 100
<Processability>
A sheet of an inner liner rubber-insulation rubber joined body having a thickness of 0.6 mm is produced by a film extruder. At that time, the sheet flatness, presence / absence of perforations, and unevenness of the sheet edge were scored. The evaluation criteria are as follows.

  A: Sheet flat, no hole, straight sheet edge, adjacent rubber and proper processing tack.

B: Although not satisfying all of A, it has workability that can be actually used.
C: Actual use is impossible.

<Rolling resistance change rate>
The rolling resistance was measured by the same method as in Example 1. And by the following calculation formula, the comparative example 15 was made into the reference | standard (± 0), and rolling resistance change rate (%) of each mixing | blending was displayed with the index | exponent. In addition, it shows that rolling resistance is reduced and is preferable, so that rolling resistance change rate is small, and specifically, it is preferable that it is negative.

(Rolling resistance change rate) = (Rolling resistance of each formulation-Rolling resistance of Comparative Example 15)
÷ (Rolling resistance of Comparative Example 15) × 100
<Static air pressure drop rate test>
The air pressure reduction rate was calculated in the same manner as in Example 1.

  The results are shown in Table 4.

<Examples 22 to 25, Comparative Examples 20 to 24>
The polymer mixture, softener, and filler according to the formulation shown in Table 5 were pelletized with a twin screw extruder (extrusion diameter: 50 mmφ, length: 1 m, temperature control: 220 ° C.), and then extruded into a T-die film. Polymer sheets of Examples 22 to 25 and Comparative Examples 20 to 24 were produced using a machine (extrusion diameter: 80 mmφ, temperature control: 220 ° C., film gauge: 0.6 mm). The following tests were conducted on the polymer sheet.

  For pneumatic tires, polymer sheets having thicknesses of 0.6 mm and 0.3 mm were prepared according to the formulation shown in Table 5, respectively, applied to the inner liner portion of the tire, and press molded at 170 ° C. for 20 minutes. A / 65R15 size tire was produced.

<Adhesion test>
A carcass was prepared by pressurizing and heating a topping rubber sheet with an adjacent carcass cord with a thickness of 2 mm, the polymer sheet with a thickness of 1 mm, and a reinforced canvas fabric at 150 ° C. for 20 minutes. Evaluation was performed according to the conditions and criteria.

<Air permeability>
The polymer sheet was measured under the same conditions as in Example 1.

<Tangent loss index>
With respect to the polymer sheet, tangent loss (tan δ) was measured under the same conditions as in Example 10. Using Comparative Example 20 as a reference (100), the tangent loss of each formulation was displayed as an index.

(Tangent loss index) = (Tangent loss of each formulation / Tangent loss of Comparative Example 20) × 100
<Processability>
A polymer sheet having a thickness of 0.6 mm is produced with a film extruder. At that time, the sheet flatness, presence / absence of perforations, and unevenness of the sheet edge were scored. The evaluation criteria are as follows.

  A: Sheet flat, no hole, straight sheet edge, adjacent rubber and proper processing tack.

B: Although not satisfying all of A, it has workability that can be actually used.
C: Actual use is impossible.

<Rolling resistance change rate>
The rolling resistance was measured by the same method as in Example 1. And by the following calculation formula, the comparative example 20 was made into the reference | standard (± 0), and rolling resistance change rate (%) of each mixing | blending was displayed with the index | exponent. In addition, it shows that rolling resistance is reduced and is preferable, so that rolling resistance change rate is small, and specifically, it is preferable that it is negative.

(Rolling resistance change rate) = (Rolling resistance of each formulation-Rolling resistance of Comparative Example 20)
÷ (Rolling resistance of Comparative Example 20) × 100
<Static air pressure drop rate test>
The air pressure reduction rate was calculated in the same manner as in Example 1.

  The results are shown in Table 5.

  In Examples 22 to 24, C5 petroleum resin, C9 petroleum resin or terpene resin was added to 100 parts by mass of a rubber component consisting of 90% by mass of a styrene-isobutylene-styrene triblock copolymer and 10% by mass of a polyamide-based polymer. It is a polymer composition containing 10 parts by mass of each. Example 25 is a C5 petroleum resin based on 100 parts by mass of a rubber component comprising 70% by mass of a styrene-isobutylene-styrene triblock copolymer, 10% by mass of a polyamide-based polymer and 20% by mass of an ethylene / vinyl alcohol copolymer. Is a polymer composition containing 10 parts by mass. These have better adhesiveness and air permeation resistance than the comparative example 20 containing chlorobutyl and NR as rubber components, and are excellent in processability.

  In Comparative Example 21, the content of styrene-isobutylene-styrene triblock copolymer is small, and the air permeation resistance and the static air decrease rate are inferior. Comparative Example 22 does not contain a polyamide-based polymer and has poor adhesion. Comparative Example 23 does not contain a styrene-isobutylene-styrene triblock copolymer and is inferior in air permeation resistance and static air reduction rate. Comparative Example 24 does not contain a styrene-isobutylene-styrene triblock copolymer and a polyamide-based polymer, and is inferior in air permeation resistance, static air reduction rate and adhesion.

<Examples 26 and 27, Comparative Examples 25 to 29>
The polymer mixture and filler according to the formulation shown in Table 6 were pelletized with a twin screw extruder (extrusion diameter: 50 mmφ, length: 1 m, temperature control: 220 ° C.), and then a T-die film extruder (extrusion). (Diameter: 80 mmφ, temperature control: 220 ° C., film gauge: 0.6 mm) Polymer films of Examples 26 and 27 and Comparative Examples 25 to 29 were produced. The following tests were conducted on a rubber paste-coated inner liner rubber in which a rubber paste having a concentration of the rubber composition shown in Table 6 was applied to the polymer film. Note that the compounding ratio of the rubber paste is 20% in concentration.

  For pneumatic tires, a polymer sheet having a thickness of 0.6 mm and 0.3 mm was prepared using a polymer film having a formulation shown in Table 6, and a rubber paste-coated inner liner rubber in which a rubber paste was applied to the polymer sheet. Each was applied to the inner liner part of the tire and press molded at 170 ° C. for 20 minutes to produce a 195 / 65R15 size tire.

<Adhesion test>
Carcass was produced by pressurizing and heating a 2 mm thick topping rubber sheet with adjacent carcass cord, 1 mm thick rubber glue coated inner liner rubber and reinforced canvas fabric at 150 ° C. for 20 minutes. Evaluation was performed according to the same conditions and criteria as in Example 1.

<Air permeability>
The rubber liner coated inner liner rubber was measured under the same conditions as in Example 1.

<Tangent loss index>
The tangent loss (tan δ) was measured under the same conditions as in Example 10 for the rubber paste coated inner liner rubber. Using Comparative Example 25 as a reference (100), the tangent loss of each formulation was displayed as an index.

(Tangent loss index) = (Tangent loss of each formulation / Tangent loss of Comparative Example 25) × 100
<Processability>
A sheet of an inner liner rubber-insulation rubber joined body having a thickness of 0.6 mm is produced by a film extruder. At that time, the sheet flatness, presence / absence of perforations, and unevenness of the sheet edge were scored. The evaluation criteria are as follows.

  A: Sheet flat, no hole, straight sheet edge, adjacent rubber and proper processing tack.

B: Although not satisfying all of A, it has workability that can be actually used.
C: Actual use is impossible.

<Rolling resistance change rate>
The rolling resistance was measured by the same method as in Example 1. And by the following calculation formula, the comparative example 25 was made into the reference | standard (± 0), and rolling resistance change rate (%) of each mixing | blending was displayed with the index | exponent. In addition, it shows that rolling resistance is reduced and is preferable, so that rolling resistance change rate is small, and specifically, it is preferable that it is negative.

(Rolling resistance change rate) = (Rolling resistance of each formulation-Rolling resistance of Comparative Example 25)
÷ (Rolling resistance of Comparative Example 25) × 100
<Static air pressure drop rate test>
The air pressure reduction rate was calculated in the same manner as in Example 1.

  The results are shown in Table 6.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The pneumatic tire of the present invention using a polymer composition excellent in the effect of suppressing the decrease in air pressure, durability and adhesion to adjacent rubber is suitable for various uses such as for passenger cars, trucks and buses, heavy machinery and the like. Can be applied to.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 2 tread part, 3 side wall part, 4 bead part, 5 bead core, 6 carcass, 6a carcass cord, 7 belt layer, 8 bead apex, 9 inner liner, 9b inner liner rubber, 10 protective film, 11 Insulation rubber.

Claims (8)

  A sidewall protective film comprising 99 to 60% by mass of a styrene-isobutylene-styrene triblock copolymer and a polymer mixture containing 1 to 40% by mass of a polyamide-based polymer having a Shore D hardness of 70 or less and containing polyamide in the molecular chain.   The sidewall protective film according to claim 1, wherein the polymer mixture contains 15 to 40% by mass of an ethylene-vinyl alcohol copolymer.   3. The sidewall protective film according to claim 1, wherein in the polymer mixture, the styrene-isobutylene-styrene triblock copolymer contains 10 to 30% by mass of styrene.   The sidewall protective film according to any one of claims 1 to 3, wherein the polymer mixture is a block copolymer in which the polyamide-based polymer includes a polyamide component and a polyether component.   The sidewall protective film according to any one of claims 1 to 4, comprising 5 to 40 parts by mass of a filler with respect to 100 parts by mass of the polymer mixture.   The sidewall protective film according to claim 5, comprising 10 to 25 parts by mass of mica as the filler with respect to 100 parts by mass of the polymer mixture.   The sidewall according to any one of claims 1 to 6, comprising 1 to 30 parts by mass of one or more selected from the group consisting of C5 petroleum resin, C9 petroleum resin and terpene resin with respect to 100 parts by mass of the polymer mixture. Protective film.   The pneumatic tire which has a side wall part provided with the side wall protective film in any one of Claims 1-7.

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