JP3217239B2 - Polymer composition for tire and pneumatic tire using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer composition for tires having an excellent balance between air permeability and flexibility.
More specifically, a tire polymer composition capable of reducing the weight of a tire by reducing the thickness of an air permeation prevention layer such as an inner liner layer without impairing the air pressure retention in the tire of a pneumatic tire, and the air permeation thereof. The present invention relates to a pneumatic tire used for a prevention layer.

[0002]

2. Description of the Related Art Reduction of the fuel consumption rate is one of the major technical issues in automobiles, and as a measure against this, there is an increasing demand for lighter pneumatic tires.

[0003] On the inner surface of a pneumatic tire, an inner liner layer made of a rubber having a low gas permeability such as butyl rubber, halogenated butyl rubber or the like is provided to keep the tire air pressure constant. However, since the halogenated butyl rubber has a large hysteresis loss, if the inner rubber of the carcass layer and the inner liner layer are wavy in the gap between the carcass cords after vulcanization of the tire, the inner liner rubber layer is deformed together with the deformation of the carcass layer. Is deformed, so that there is a problem that rolling resistance increases. Therefore, in general, the inner liner layer (halogenated butyl rubber) and the inner surface rubber of the carcass layer are bonded to each other via a rubber sheet called a tie rubber having a small hysteresis loss. Accordingly, in addition to the thickness of the inner liner layer of the halogenated butyl rubber, the thickness of the tie rubber is added, and the entire layer is 1 mm (1 mm).
000 μm), resulting in one of the causes of increasing the weight of the product tire.

A technique has been proposed in which various materials are used in place of a low gas permeable rubber such as butyl rubber as an inner liner layer of a pneumatic tire. For example,
No. 3,176,61 discloses that an air permeability coefficient [cm ³ (standard condition) / cm · sec · mmHg] is 1 at 30 ° C. on the inner surface of a vulcanized tire.
It is disclosed that a solution or dispersion of a synthetic resin such as polyvinylidene chloride, a saturated polyester resin, or a polyamide resin of 0 × 10 ⁻¹³ or less and 50 × 10 ⁻¹³ or less at 70 ° C. is applied at 0.1 mm or less. I have.

However, the technology disclosed in this publication is
On the inner peripheral surface of the carcass of the vulcanized tire, or on the inner peripheral surface of the inner liner, a coating layer of a synthetic resin having a specific air permeability coefficient is provided to reduce the thickness of the synthetic resin coating layer to 0.1 mm or less. However, the pneumatic tire described in this publication has a problem in adhesion between the rubber and the synthetic resin, and also has a drawback that the inner liner layer has poor moisture resistance (or water resistance).

JP-A-5-330307 discloses that the inner surface of a tire is subjected to a halogenation treatment (using a conventionally known chlorination treatment solution, a bromine solution and an iodine solution), and methoxymethylated nylon, Polymer film of polymerized nylon, blend of polyurethane and polyvinylidene chloride, blend of polyurethane and polyvinylidene fluoride (film thickness 1
0-200 [mu] m).

Further, Japanese Patent Application Laid-Open No. Hei 5-318618 discloses that
A pneumatic tire using a thin film of methoxymethylated nylon as an inner liner is disclosed. According to this technology, a solution or emulsion of methoxymethylated nylon is sprayed or applied to the inner surface of a green tire, and then the tire is vulcanized. Alternatively, a pneumatic tire is manufactured by spraying or applying a solution or emulsion of methoxymethylated nylon on the inner surface of the tire after vulcanization. However, even the techniques disclosed in these publications have a disadvantage that it is difficult to maintain uniformity of the film thickness in addition to a disadvantage that the thin film has poor water resistance.

Further, JP-A-6-40207 discloses that
A multilayer film having a low air permeable layer made of a polyvinylidene chloride film or an ethylene vinyl alcohol copolymer film and an adhesive layer made of a polyolefin film, an aliphatic polyamide film, or a polyurethane film is used as an air permeation preventing layer of a tire. There is an example used. However, in this system, the low air permeable layer lacks flexibility, and the film cannot follow the expansion and contraction of the material during running of the tire, and cracks may occur.

Further, JP-A-5-508435 discloses a composition for a tire inner liner containing a halogen-containing copolymer of a C ₄ -C ₇ isomonoolefin and a p-alkylstyrene containing carbon black, a plasticizer oil and a vulcanizing agent. Although it has been proposed to use the composition for tire innerliners, such innerliners have insufficient air permeability and are not suitable for further tire weight reduction.

[0010]

As described above, various materials for the inner liner layer of a pneumatic tire have been proposed in place of butyl rubber, but have not yet been put to practical use. Particularly, a material excellent in balance between air permeability resistance and flexibility required for an inner liner layer of a pneumatic tire has not yet been developed. Accordingly, an object of the present invention is to provide a tire which is capable of reducing the weight of a tire without impairing the air pressure retention of the pneumatic tire, has an adhesive property with a rubber layer, and is suitable for an air permeation preventing layer of a pneumatic tire. An object of the present invention is to provide a polymer composition for use and a pneumatic tire comprising an air permeation preventing layer using the same.

[0011]

According to the present invention, (A)
An air permeability coefficient ( JIS K71) selected from the group consisting of polyamide resin, polyester resin, polynitrile resin, cellulose resin, fluorine resin and imide resin.
Measured at 30 ° C. according to 26) is ^{25 × 10 -12 cc · cm /} c
at least one thermoplastic resin having a Young's modulus of more than 500 MPa at m ² .sec.
0% by weight or more and (B) air permeability coefficient (30 in accordance with JIS K7126 )
℃ ・ measured at 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg
The total amount of component (A) and component (B) (A) + (B) is at least one elastomer component having a Young's modulus of not more than 500 MPa and not less than 10% by weight based on the weight of all polymer components.
Is contained in an amount of not less than 30% by weight based on the weight of the total polymer components, and the components (A) and (B) are melt-kneaded and dynamically vulcanized so that the elastomer component (B) forms a discontinuous phase in the composition. And has an air permeability coefficient ( JIS K7
Measured at 30 ° C. according to No. 126 ) is 25 × 10 ⁻¹² cc · cm
The present invention provides a polymer composition for tires having a Young's modulus of 1 to 500 MPa at a pressure of not more than / cm ² · sec · cmHg.

According to the present invention, there is also provided a pneumatic tire using the above polymer composition for a tire in an air permeation preventing layer.

The thermoplastic resin blended as the component (A) in the polymer composition according to the present invention has an air permeability coefficient of 2
5 × 10 ^-12 cc · cm / cm ² · sec · cmHg or less, preferably 0.1 × 10 ^-12 to 10 × 10 ^-12 cc · cm / cm ² · se
c ・ cmHg and Young's modulus is over 500MPa, preferably 500
Any thermoplastic resin having a pressure of up to 3000 MPa can be used, and the amount thereof is 10% by weight or more, preferably 20 to 85% by weight, based on the total weight of the polymer components including the resin and the rubber.

Examples of such thermoplastic resins include the following thermoplastic resins and any of these or any resin mixtures containing them.

A polyamide resin (for example, nylon 6 (N
6), nylon 66 (N66), nylon 46 (N4
6), nylon 11 (N11), nylon 12 (N1
2), nylon 610 (N610), nylon 612
(N612), nylon 6/66 copolymer (N6 / 6
6), nylon 6/66/610 copolymer (N6 / 66
/ 610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP
Copolymer, nylon 66 / PPS copolymer), polyester resin (for example, polybutylene terephthalate (PB
T), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylenediimidic acid / polybutyrate Aromatic polyesters such as terephthalate copolymer), polynitrile resins (eg, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / Styrene / butadiene copolymer),
Cellulosic resins (eg, cellulose acetate, cellulose acetate butyrate), fluororesins (eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE) )) And imide-based resins (eg, aromatic polyimide (PI)).

As described above, these thermoplastic resins must have a specific air permeability coefficient, Young's modulus and blending amount. It has a flexibility of Young's modulus of 500 MPa or less and an air permeability coefficient of 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg.
The following materials are not yet industrially developed and have an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec.
-If it exceeds cmHg, the air permeation resistance as a polymer composition for tires is lowered, and the tire does not function as an air permeation preventing layer. Further, when the blending amount of these thermoplastic resins is less than 10% by weight, the air permeation resistance similarly decreases, and it is not preferable to use as a tire air permeation preventing layer.

The elastomer component blended as the component (B) in the resin composition according to the present invention has an air permeability coefficient of 2
Any elastomer having a modulus greater than 5 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg and a Young's modulus of 500 MPa or less, or any blend thereof, or for improving the dispersibility and heat resistance of the elastomer in these elastomers, etc. Reinforcing agents, fillers, cross-linking agents, softeners generally compounded in elastomers,
An elastomer composition to which a necessary amount of a compounding agent such as an antioxidant and a processing aid has been added. The compounding amount is 10% by weight based on the total amount of the polymer component including the resin and the elastomer component constituting the air permeation preventing layer. Above, preferably 10
85% by weight.

The elastomer constituting such an elastomer component is not particularly limited as long as it has the above air permeability coefficient and Young's modulus, and examples thereof include the following.

Diene rubber and its hydrogenated product (for example, N
R, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubber (eg, ethylene propylene rubber (EPDM, EPM), maleic acid modified) Ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer), halogen-containing rubber (for example, brominated butyl rubber (Br-IIR), chlorinated butyl rubber) (Cl-IIR), bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHR, CH)
C), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid-modified chlorinated polyethylene (M-CM)), silicone rubber (for example, methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber) , Sulfur-containing rubber (for example, polysulfide rubber), fluorine rubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer ( Examples thereof include styrene-based elastomers, polyolefin-based elastomers, polyester-based elastomers, polyurethane-based elastomers, and polyamide-based elastomers.

As an elastomer component, C ₄ as disclosed in the above-mentioned JP-A-5-508435 is used.
-C ₇ isomonoolefin and p- alkylstyrene halogen (e.g. Br, Cr, I) a containing copolymer rubber, p- alkylstyrene content of 5.5 to 25% by weight of the total copolymer rubber , Preferably 6.0 to 20% by weight,
When the halogen content is 1.0% by weight or more, preferably 1.0% by weight.
Mooney viscosity ML _{1 + 8} (125 ° C) at ~ 5.0 wt%
However, a copolymer rubber of 30 or more, preferably 35 to 70 can be used. When this rubber is used, the weight ratio of the component (A) to the component (B) is (A) / (B) = 10/9.
It is 0-90 / 10, preferably 15 / 85-85 / 15.

If the copolymer rubber has a p-alkylstyrene content of less than 5.5% by weight, the resulting polymer composition for tires has poor air permeability, which is not preferred.
Conversely, if it exceeds 25% by weight, the composition is apt to become brittle at a low temperature, which is not preferable. If the halogen content is less than 1.0% by weight, the mechanical strength such as tensile strength is undesirably reduced, and if the Mooney viscosity is less than 30, the air permeability is also undesirably reduced. Further, the component (A) /
If the blending ratio (by weight) of the component (B) is less than 10/90, the air permeation resistance also decreases, which is not preferable. If it exceeds 90/10, the flexibility decreases, which is not preferable.

One of such copolymer rubbers is commercially available as EXXPRO from EXXON CHEM. For example, a copolymer rubber of isobutylene having the structure (A) represented by the following formula and p-methylstyrene may be used. B
It is a copolymer rubber of the following structure (B) partially brominated with r ₂ . This can be suitably used in the present invention.

[0023]

Embedded image

When the compatibility between the specific thermoplastic resin and the elastomer component is different, it is preferable to use a suitable compatibilizing agent as the third component to compatibilize the two components.
By mixing the compatibilizer into the system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the rubber particles forming the dispersion layer become finer, so that the properties of both components are more improved. It will be effectively expressed. Such a compatibilizer is generally a copolymer having a structure of both or one of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen group, an amino group capable of reacting with the thermoplastic resin or the elastomer component. It can be a copolymer having a group, an oxazoline group, a hydroxyl group and the like. These may be selected according to the type of thermoplastic resin and elastomer component to be mixed,
Commonly used ones are styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid-modified product, EPDM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid-modified product, styrene / maleic acid Copolymers, reactive phenoxy resins and the like can be mentioned. The amount of the compatibilizer is not particularly limited, but is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymer component (total of the thermoplastic resin and the elastomer component).

The composition ratio between the specific thermoplastic resin (A) and the elastomer component (B) may be appropriately determined depending on the balance of the film thickness, air permeability resistance and flexibility, but the preferred range is the weight ratio. It is 10/90 to 90/10, more preferably 20/80 to 85/15.

In the polymer composition according to the present invention, as a third component in addition to the polymer components of the above essential components (A) and (B), as long as the necessary properties of the polymer composition for a tire of the present invention are not impaired. Other polymers, such as the compatibilizer polymers described above, can be mixed. The purpose of mixing the other polymer is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the film forming processability of the material, to improve the heat resistance, to reduce the cost, and the like. As a material to be used, for example, polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, SBS, polycarbonate (PC)
And the like. The air permeability coefficient and Young's modulus of the polymer of the third component (C) are not particularly limited as long as they have predetermined values as the polymer composition.

As described above, the polymer composition according to the present invention contains polymer components (A) and (B) having specific air permeability and Young's modulus as essential components. 1, wherein component (A) corresponds to region X, component (B) corresponds to region Y, and the resulting polymer composition corresponds to region Z.

In the present invention, a heat-resistant material belonging to the component (A)
Plastic resin A₁~ A_n(Where the i-th thermoplastic
Resin A_iA's Young's modulus_ix, The air permeability coefficient is A_iyage
A_i= (A_ix, A_iy)) And their average value Aa
v (= Σφi (A_ix, A_iy) (I = 1 to n), where φ
i is the weight fraction of Ai). This point Aav and air permeability
Excess coefficient is 25 × 10^-12cc ・ cm / cm^Two・ Sec ・ cmHg, ya
A point P with a working rate of 500 MPa is connected with a straight line, and a straight line AavP
And the air permeation coefficient 25 × 1
0^-12cc ・ cm / cm^Two・ Sec ・ Y area in area S over cmHg
(B) component belonging to the region, B₁~ B_nAverage value Bav (=
Σφi (B_ix, B_iy) (I = 1 to n), where φi is B
weight fraction of i, B_ixIs the i-th elastomer component
Rate, B _iyIs the air permeability of the i-th elastomer component
(A) is selected, and the component (A)
The desired area can be obtained by mixing the component (B) with an appropriate mixture.
A polymer composition that enters Z can be obtained.

Hereinafter, a pneumatic tire having an air permeation preventing layer manufactured using the polymer composition for a tire of the present invention will be described in more detail. The air permeation prevention layer of the pneumatic tire according to the present invention can be arranged at an arbitrary position inside the tire, that is, inside or outside the carcass layer, or at another position. In short, the object of the present invention is achieved by arranging the tire so as to prevent transmission and diffusion of air from the inside of the tire and maintain the air pressure inside the tire for a long period of time.

FIG. 2 is a meridional half cross-sectional view illustrating a typical example of the arrangement of the air permeation preventing layer of the pneumatic tire. In FIG. 2, a carcass layer 2 is mounted between a pair of left and right bead cores 1, 1, and an inner liner layer 3 is provided on the inner surface of the tire inside the carcass layer 2. The inner liner layer 3 is composed of the polymer composition for a tire in the present invention. In FIG. 2, reference numeral 4 denotes a sidewall.

In the present invention, the method for producing the polymer composition constituting the air permeation preventing layer is as follows: a thermoplastic resin and an elastomer component (unvulcanized in the case of rubber) are melt-kneaded in advance by a twin-screw kneading extruder or the like. By dispersing an elastomer component in a thermoplastic resin forming a continuous phase. When vulcanizing the elastomer component, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer component. Also,
Various additives (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading,
It is preferable to mix them before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer component is not particularly limited, and examples thereof include a screw extruder, a kneader, a Banbury mixer, and a twin-screw kneading extruder. Among them, it is preferable to use a twin-screw kneading extruder for kneading the thermoplastic resin and the elastomer component and for dynamic vulcanization of the elastomer component. Further, two or more types of kneaders may be used to knead sequentially. As a condition for the melt-kneading, the temperature may be at least the temperature at which the thermoplastic resin melts. Further, the shear rate during kneading is preferably 1000 to 7500 Sec ^-1 . The total kneading time is 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanizing time after addition is 15 seconds to 5 minutes.
Minutes is preferred. The polymer composition produced by the above method is then formed into a film by extrusion or calendering. The method of forming a film may be a method of forming a normal thermoplastic resin or thermoplastic elastomer into a film.

The thin film thus obtained has a structure in which the elastomer component (B) is dispersed as a discontinuous phase in the matrix of the thermoplastic resin (A). By taking a dispersed structure in such a state, it is possible to impart a balance between flexibility and air permeability resistance, and to obtain effects such as improvement in heat deformation resistance, improvement in water resistance, and thermoplastic processing. Since it becomes possible, it becomes possible to form a film by a usual resin molding machine, that is, extrusion molding or calender molding. The method of forming a film may be a method of forming a normal thermoplastic resin or thermoplastic elastomer into a film.

The method for manufacturing a pneumatic tire having an air permeation preventing layer formed of a thin film of the polymer composition according to the present invention is applied to a case where the inner liner layer 3 is disposed inside the carcass layer 2 as shown in FIG. To explain one example,
The polymer composition of the present invention is extruded into a thin film having a predetermined width and thickness in advance, and the thin film is adhered to a cylinder on a tire building drum. Members used for normal tire production, such as a carcass layer, a belt layer, a tread layer, and the like made of unvulcanized rubber are sequentially laminated thereon, and the drum is pulled out to obtain a green tire. Next, by heating and vulcanizing the green tire according to a conventional method, a desired lightweight pneumatic tire can be manufactured. In addition, also when providing an air permeation prevention layer on the outer peripheral surface of a carcass layer, it can be performed according to this.

The material of the rubber layer to which the air permeation prevention layer according to the present invention is adhered is not particularly limited, and may be any rubber material conventionally used as a rubber material for tires. Examples of such rubbers include diene rubbers such as NR, IR, BR, SBR, halogenated butyl rubber, ethylene-propylene copolymer rubber,
A rubber composition can be obtained by adding compounding agents such as carbon black, process oil, and vulcanizing agent to a styrene-based elastomer or the like.

The air permeation preventing layer according to the present invention has
Coefficient is 25 × 10^-12cc ・ cm / cm^Two・ Sec ・ cmHg or less,
Preferably 5 × 10^-12cc ・ cm / cm^Two・ Sec ・ cmHg or less
It is. Although there is no particular lower limit for the air permeability coefficient,
0.05 × 10^-12cc ・ cm / cm ^Two・ Sec ・ cmHg.
25 × 10 air permeation^-12cc ・ cm / cm^Two・ Sec ・ cmHg
By setting the thickness of the air permeation prevention layer to
It can be less than half the thickness of the air permeation prevention layer
You.

On the other hand, the Young's modulus is 1 to 500 MPa, preferably 10 to 300 MPa, and the thickness is 0.02 to 1.0 mm, preferably 0.05 to 0.5 mm. Young's modulus is 1MPa
If it is less than 500 MPa, it is not preferable because handling becomes difficult due to wrinkles and the like, and if it exceeds 500 MPa, it is not preferable because it cannot follow the deformation of the tire during running.

[0037]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples. The evaluation methods used in the following examples are as follows.

Measurement Method of Air Permeability Coefficient of Film According to JIS K7126 "Test Method for Gas Permeability of Plastic Films and Sheets (Method A)". Test piece: The film sample prepared in each example was used. Test gas: air (N ₂ : O ₂ = 8: 2) Test temperature: 30 ° C

Measurement method of Young's modulus of film According to JIS K6251 “Tensile test method for vulcanized rubber”. Test piece: The film sample prepared in each example was subjected to JIS3 in parallel with the resin extrusion direction at the time of film extrusion molding.
No. Dumbbell punched out. A tangent was drawn on a curve in the initial strain region of the obtained stress-strain curve, and the Young's modulus was determined from the slope of the tangent.

Tire Air Leak Performance Test Method 165SR13 Steel Radial Tire (Rim 13
× 41/2 -J), the pressure was measured every 4 days at an initial pressure of 200 kPa under no load conditions at room temperature of 21 ° C. for 3 months. As the measured pressure Pt, the initial pressure Po, and the number of elapsed days t, an α value is obtained by regressing on the function: Pt / Po = exp (−αt). Using the obtained α, t = 30
Is substituted into the following equation to obtain β = [1-exp (−αt)] × 100 β value. This β value is calculated as the pressure drop rate per month (% /
Month).

Table I shows the brands and basic physical properties of the polymers used in the following Examples and Comparative Examples. Here, as for the basic physical properties of the rubber in the elastomer component, the raw material alone cannot maintain its shape and it is difficult to measure some materials. Is shown. Table III shows the brands of each compounding agent.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

Examples 1 to 8 One or two of the various thermoplastic resin components (A) and the elastomer component (B) and, if necessary, in various proportions (parts by weight) shown in Tables IV to XI. Other components such as a sulfurizing agent and a lubricating material were kneaded with a biaxial kneader and pelletized, and then formed into a film having a width of 350 mm and a thickness of 0.1 mm by an extruder. The air permeability coefficient and the Young's modulus of the obtained film were measured, and the results are shown in Tables IV to XI, respectively.

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

[Table 9]

[0052]

[Table 10]

[0053]

[Table 11]

[0054]

[Table 12]

[0055]

[Table 13]

[0056]

[Table 14]

Example 9 Various thermoplastic resin components (A), elastomer components (B), and third components (polycarbonates) were added at various mixing ratios (parts by weight) shown in Table XII, and in some cases, a vulcanizing agent, a lubricant, Materials and other components were kneaded with a biaxial kneader and pelletized, and then extruded into a film having a width of 350 mm and a thickness of 0.2 mm. The air permeability coefficient and Young's modulus of the obtained film were measured, and the results are shown in Table XII.

[0058]

[Table 15]

Examples 10 to 13 and Comparative Example 1 Various compounding agents were mixed with Br-IIR and Br-IPMS, and master batches A and B were prepared in a closed Banbury mixer. The masterbatch formulation is shown in Table XIII.

[0060]

[Table 16]

These master batches are pelletized using a rubber pelletizer, kneaded with a resin material and a crosslinking agent in a biaxial kneader at various mixing ratios (parts by weight) shown in Table XIV, pelletized, and then extruded. 350mm wide and 0mm thick.
A 1 mm film was produced. The air permeability coefficient and Young's modulus of the obtained film were measured. Further, these films were wound around a drum for forming a tire, and tire members such as a carcass, a side belt, and a tread were laminated thereon and inflated to obtain a green tire. The green tire is vulcanized at 180 ° C for 10 minutes with a vulcanizer,
The tire was finished with a tire size of 165SR13.

On the other hand, as a comparative example, a green tire having an inner liner layer of about 0.5 mm made of unvulcanized butyl rubber was formed on the inner surface of the green tire via a tie rubber having a thickness of about 0.7 mm. The tire was finished by vulcanization (size 165SR13). The composition of the inner liner layer, the air permeability coefficient and the Young's modulus are shown in the same manner as in the examples.
XIV. The weight of the inner liner layer of the obtained pneumatic tire was measured and an air leak test was performed. Table of results
See XIV.

[0063]

[Table 17]

Example 14 Eight types of brominated polyisobutylene-p shown in Table XV
N11 as a thermoplastic resin component in the same manner as described in the above example using methylstyrene copolymer rubber.
(Rilsan BESN O TL) (see Table I), N6 /
66 (Ultramid C35) (see Table I)
I, air permeability coefficient and Young's modulus were evaluated based on the mixing ratio of the polymers shown in Tables XVII and XVIII. The results are shown in Table XVI to Table
Shown in XVII. The rubber composition of the modified polyisoprene rubber was as follows. Rubber compounding Modified polyisobutylene rubber 100 parts by weight Zinc stearate 1 part by weight Stearic acid 2 parts by weight Zinc flower 3 0.5 part by weight

[0065]

[Table 18]

[0066]

[Table 19]

[0067]

[Table 20]

[0068]

[0069]

As described above, according to the present invention,
It is possible to obtain a polymer composition for a tire suitable for an air permeation prevention layer of a pneumatic tire, which can maintain the air pressure retention property in the tire satisfactorily and maintain the flexibility while reducing the weight of the tire. it can.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the air permeability and the Young's modulus of the polymer components (A) and (B) according to the present invention and the polymer composition of the present invention.

FIG. 2 is a half sectional view in the meridian direction showing a structure of an inner liner portion of the pneumatic tire of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bead core 2: Carcass layer 3: Inner liner layer 4: Side wall

Continuation of the front page (72) Inventor Noriaki Kuroda 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Works (72) Inventor Katsuhiro Igawa 2-1 Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Hiratsuka Works (56) References JP-A-1-314164 (JP, A) JP-A-7-70372 (JP, A) JP-A-4-503964 (JP, A) US Pat. No. 4,984,871 (US, A) (58) Search Field (Int.Cl. ⁷ , DB name) C08L 21/00 C08L 101/00 B60C 5/14 B29D 30/06

Claims (4)

(57) [Claims] 1. An air permeability coefficient (at 30 ° C. according to JIS K7126) selected from the group consisting of (A) a polyamide resin, a polyester resin, a polynitrile resin, a cellulose resin, a fluorine resin and an imide resin. Measurement) is 2
^{5 × 10 -12 cc · cm /} cm 2 · sec · cmHg or less at Young's modulus 500MPa greater of at least one thermoplastic resin at least 10 wt% total polymer component weight per well (B) in the air permeation coefficient (JIS K7126 According to 30
℃ ・ measured at 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg
The total amount of component (A) and component (B) (A) + (B) is at least one elastomer component having a Young's modulus of not more than 500 MPa and not less than 10% by weight based on the weight of all polymer components.
Is contained in an amount of not less than 30% by weight based on the weight of the total polymer components, and the components (A) and (B) are melt-kneaded and dynamically vulcanized so that the elastomer component (B) forms a discontinuous phase in the composition. And has an air permeability coefficient ( JIS K7
Measured at 30 ° C. according to No. 126 ) is 25 × 10 ⁻¹² cc · cm
/ Cm ² · sec · A polymer composition for tires having a Young's modulus of 1 to 500 MPa at or below cmHg. 2. The elastomer of component (B) is at least one selected from the group consisting of diene rubbers and hydrogenated products thereof, olefin rubbers, halogen-containing rubbers, silicone rubbers, sulfur-containing rubbers, fluororubbers, and thermoplastic elastomers. The polymer composition for a tire according to claim 1, which is a kind of elastomer. 3. An elastomer component (B) comprising C ₄ -C
_7. A halogen-containing copolymer rubber of isomonoolefin and p-alkylstyrene, having a p-alkylstyrene content of 5.5 to 25% by weight, a halogen content of 1.0% by weight or more and a Mooney viscosity ML _{1 +8} (125 ° C.) A rubber containing a copolymer rubber having a value of 30 or more, and a weight ratio (A) / thermoplastic component (A) / elastomer component (B) /
The polymer composition for a tire according to claim 1, wherein (B) is from 10/90 to 90/10. 4. A pneumatic tire using a thin film of the polymer composition for a tire according to claim 1 as an air permeation prevention layer.