JP5041726B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a decrease in air pressure is prevented and durability and fuel consumption are improved.

  The pneumatic tire is filled with high-pressure air, and an inner liner layer is usually provided to suppress a decrease in air pressure when the tire is used. Conventionally, chlorinated butyl rubber or brominated butyl rubber is used for the inner liner layer. However, it is not preferable from the viewpoint of environmental problems that chlorine or bromine is contained. Chlorine and bromine also have the problem of destroying the adhesion between the ply cord and the rubber and reducing the durability of the tire.

  Patent Document 1 aims to obtain a pneumatic tire with reduced air permeability. As rubber components, butyl rubber, halogenated butyl rubber, a co-polymer of 4 to 7 carbon monoisoolefin and paraalkylstyrene are used. 60 to 100% by weight of at least one butyl rubber selected from the group consisting of polymer halides, and a group consisting of natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber and styrene-isoprene-butadiene rubber An average particle size of 5 μm or less and an average aspect ratio of 50 to 5000 are provided on the inner side of the inner liner layer made of a rubber composition containing 0 to 40% by weight of at least one diene rubber selected from A pneumatic tire having a gas barrier layer made of an inorganic layered compound and a resin It is draft. However, in the technique of Patent Document 1, another layer is provided on the inner surface side of the inner liner layer, so that the process is complicated. There is also room for improvement in terms of reducing fuel consumption.

Patent Document 2 discloses 100 parts by weight of a rubber component made of butyl rubber as a rubber composition for an inner liner that can be reduced in weight, reduced in rolling resistance, and reduced in air permeation without lowering durability. In contrast, 35 to 80 parts by weight of inorganic filler and 5 to 30 parts by weight of polypropylene powder, and the following formula: (blend amount of polypropylene powder) ≦ (blend amount of inorganic filler + blend amount of polypropylene powder) / 2. A rubber composition for an inner liner satisfying 2 is proposed. However, in the technique of Patent Document 2, it is necessary to form the inner liner layer with a certain thickness in order to ensure the gas barrier property of the inner liner layer, and there is still room for improvement in terms of improving fuel consumption by reducing the weight of the tire. .
JP 2004-196254 A Japanese Patent Laid-Open No. 2005-113027

  An object of the present invention is to provide a pneumatic tire capable of solving the above-described problems and simultaneously realizing suppression of a decrease in air pressure, improvement in durability, and improvement in fuel consumption.

  The present invention relates to the following general formula (I) with respect to 100 parts by mass of a rubber component comprising natural rubber and / or synthetic rubber:

(Wherein, m and n are each independently 1 to 100, and x is 1 to 1000)
It is related with the pneumatic tire which uses for the inner liner layer the rubber composition for inner liners in which the ethylene-vinyl alcohol copolymer represented by these was contained at least in the range of 15-30 mass parts.

  In the present invention, the rubber composition for the inner liner has the following general formula (II),

(Wherein R is an alkyl group, p and q are each independently 1 to 100, and y is 1 to 5)
It is preferable to further contain a compatibilizing agent represented by:

  The content of the compatibilizer is preferably in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

  In the present invention, the rubber composition for the inner liner may further contain at least one selected from carbon black, silica, and mica within a range of 10 to 80 parts by mass with respect to 100 parts by mass of the rubber component. preferable.

  In the present invention, the content of the halogenated rubber in the rubber component is preferably in the range of 60 to 100% by mass.

  In the present invention, the rubber composition for the inner liner is preferably cross-linked with sulfur or peroxide.

  In this invention, it is preferable that the thickness of the inner liner layer measured in the tire maximum width position of the state filled with the prescribed internal pressure is within a range of 0.1 to 5 mm.

  According to the present invention, by using a rubber composition for an inner liner excellent in gas barrier properties for an inner liner layer, a decrease in air pressure during use of a pneumatic tire is satisfactorily suppressed while maintaining good durability, and The fuel consumption can be improved by reducing the weight of the pneumatic tire.

  In the pneumatic tire of the present invention, with respect to 100 parts by mass of a rubber component made of natural rubber and / or synthetic rubber, the following general formula (I),

(Wherein, m and n are each independently 1 to 100 and x is 1 to 1000), and at least the ethylene-vinyl alcohol copolymer represented by 15 to 30 parts by mass is contained. The rubber composition for the inner liner is used for the inner liner layer. The ethylene-derived portion of the ethylene-vinyl alcohol copolymer imparts good compatibility between the rubber composition for the inner liner and the rubber component, and the ethylene-vinyl alcohol copolymer is fine in the rubber composition for the inner liner. Can exist in various dispersion sizes. 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, the inner liner layer is thinned because the ethylene-vinyl alcohol copolymer excellent in gas barrier properties is dispersed in an island shape in a fine size in the rubber composition for the inner liner. Even in this case, 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.

  Furthermore, in the present invention, in order to ensure gas barrier properties by including an ethylene-vinyl alcohol copolymer, halogens having a high specific gravity that have been conventionally used for imparting gas barrier properties such as halogenated butyl rubber. It is possible to reduce the amount of use even when the vulcanized rubber is not used or used. This also makes it possible to reduce the weight of the tire and to improve the fuel efficiency. 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 effect of improving the durability of the pneumatic tire by improving the adhesion between the ply cord and the rubber 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 in which compatibility with the rubber component and gas barrier properties are compatible is obtained. In view of better compatibility with the rubber component, 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. In addition, n is preferably 95 or less, and more preferably 80 or less, from the viewpoint that it is difficult to impair good compatibility with the rubber component 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 during the production of the inner liner rubber composition is ensured, and an inner liner rubber composition in which the ethylene-vinyl alcohol copolymer is uniformly dispersed is obtained. In view of good compatibility with the rubber component and gas barrier properties, x is preferably 10 or more, and in terms of good kneadability, x is further 500 or less, further 100. The following is preferable.

  The ethylene-vinyl alcohol copolymer represented by the general formula (I) is contained within a range of 15 to 30 parts by mass with respect to 100 parts by mass of the rubber component. When the content of the ethylene-vinyl alcohol copolymer with respect to 100 parts by mass of the rubber component is 15 parts by mass or more, the gas barrier property of the inner liner layer is ensured. Further, when the content is 30 parts by mass or less, kneadability at the time of producing the rubber composition for the inner liner is secured, and basic performance such as mechanical strength is secured in the inner liner layer. The content is preferably 17 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 28 parts by mass or less, and further preferably 25 parts by mass or less.

  The rubber composition for the inner liner has the following general formula (II):

(Wherein R is an alkyl group, p and q are each independently 1 to 100, and y is 1 to 5). The compatibilizing agent has an action of further enhancing the compatibility between the rubber component and the ethylene-vinyl alcohol copolymer in the rubber composition for the inner liner. When p and q in general formula (II) are each 1 or more, the action as a compatibilizer is good, and when p and q are each 100 or less, the phase in the rubber composition for an inner liner Dispersibility of the solubilizer is good. 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.

  In general formula (II), y is 1 or more in order to constitute a block copolymer. In addition, y is preferably 5 or less from the viewpoint that the dispersibility of the compatibilizer in the rubber composition for the inner liner is good. y is preferably 2 or more, and more preferably 4 or less.

  The content of the compatibilizer represented by the general formula (II) with respect to 100 parts by mass of the rubber component is preferably in the range of 0.1 to 5 parts by mass. When the content is 0.1 parts by mass or more, the action as a compatibilizing agent is favorably expressed, and when it is 5 parts by mass or less, the basic performance such as mechanical strength is reduced in the inner liner layer. Can be prevented. The content is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.5 parts by mass or more, and further 4.5 parts by mass or less, and further 4.0 parts by mass. Part or less, preferably 3.5 parts by weight or less.

  In addition, the ethylene-vinyl alcohol copolymer represented by the general formula (I) may be contained in the rubber composition for the inner liner in a state of being a copolymer with other components. The content of the ethylene-vinyl alcohol copolymer means the content of the structural portion represented by the general formula (I). Further, when the compatibilizing agent represented by the general formula (II) is contained in the present invention, the compatibilizing agent is a copolymer with other components in the rubber composition for the inner liner. In this case, the content of the compatibilizer means the content of the structural portion represented by the general formula (II).

  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).

  In the present invention, it is preferable that the rubber composition for an inner liner further includes at least one selected from carbon black, silica, and mica. In this case, the mechanical strength and gas barrier properties of the rubber composition for the inner liner are improved. The content of at least one selected from carbon black, silica, and mica is preferably in the range of 10 to 80 parts by mass with respect to 100 parts by mass of the rubber component. When the content is 10 parts by mass or more, the mechanical strength of the rubber composition for the inner liner is increased, so that the durability of the tire is improved. When the content is 80 parts by mass or less, the rubber composition for the inner liner is produced. Good workability. The content is further preferably 12 parts by mass or more, further 15 parts by mass or more, more preferably 50 parts by mass or less, and further preferably 30 parts by mass or less.

As the carbon black, for example, those having a nitrogen adsorption specific surface area of 100 m ² / g or more and 1500 m ² / g or less are preferably used. When the nitrogen adsorption specific surface area is 100 m ² / g or more, the reinforcing effect is good, and when the nitrogen adsorption specific surface area is 1500 m ² / g or less, it is preferable in terms of securing workability at the time of production.

As the silica, those generally used for general-purpose rubber can be used, and examples thereof include dry method white carbon, wet method white carbon and colloidal silica used as a reinforcing material. Among these, wet method white carbon mainly containing hydrous silicic acid is preferable. Nitrogen adsorption specific surface area of the silica (BET method), for example, 50 to 300 m ² / g, it is preferably further in the range of 100 to 200 m ² / g. When the nitrogen adsorption specific surface area of silica is 50 m ² / g or more, the durability of the tire is improved by sufficiently obtaining a reinforcing effect on the rubber composition for the inner liner. On the other hand, when the nitrogen adsorption specific surface area is 300 m ² / g or less, the processability of the rubber composition for the inner liner is good. Here, the nitrogen adsorption specific surface area is a value measured by the BET method according to ASTM D3037-81.

  The hardness of the rubber composition for an inner liner of the present invention can be in the range of 30 to 90. When the hardness is 30 or more, the mechanical strength of the inner liner rubber composition is good, and when it is 90 or less, it is possible to prevent a decrease in durability due to the inner liner rubber composition becoming too hard. The hardness is preferably 40 or more, more preferably 45 or more, and more preferably 55 or more, and further preferably 80 or less, and further 75 or less. The hardness is a value measured according to JIS K6250 or the like.

  The content of the halogenated rubber in the rubber component of the inner liner rubber composition is preferably in the range of 60 to 100% by mass. When the content of the halogenated rubber is 60% by mass or more, good gas barrier properties are imparted to the inner liner layer. The content can be set to 100% by mass. When the content is 90% by mass or less, the effect of improving the fuel consumption by reducing the weight of the tire can be obtained more favorably, and between the ply cord and the rubber by the halogen. The breakage of the adhesion is suppressed, and the durability of the pneumatic tire is improved. The content of the halogenated rubber is more preferably 70% by mass or more.

  In the present invention, the rubber composition for the inner liner is preferably crosslinked with sulfur or peroxide. In this case, the mechanical strength of the inner liner layer is good, and the effect of preventing a decrease in air pressure due to gas barrier properties can be maintained for a long time.

  In this invention, it is preferable that the thickness of the inner liner layer measured in the tire maximum width position of the state filled with the prescribed internal pressure is within a range of 0.1 to 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 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 preferably 0.5 mm or more, more preferably 1 mm or more, and further preferably 3 mm or less, and further preferably 2 mm or less.

  The specific gravity of the rubber 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.

  In the present invention, natural rubber and / or synthetic rubber can be used as the rubber component used in the rubber composition for the inner liner, and diene rubber is particularly preferable. Examples of the diene rubber include natural rubber and synthetic rubber such as ethylene propylene-diene terpolymer (EPDM), styrene butadiene rubber (SBR), butadiene rubber, isoprene rubber, butyl rubber, halogenated butyl rubber, and acrylonitrile-butadiene. Rubber (NBR) or the like can be used. These rubbers can be used alone or in combination of two or more as a rubber component.

  In the rubber composition for an inner liner used in the present invention, the following various components blended in other ordinary tire rubber compositions can be appropriately blended.

  As the crosslinking agent, an organic peroxide or a sulfur-based vulcanizing agent is preferably used, and may be blended within a range of, for example, 3 to 8 parts by mass with respect to 100 parts by mass of the rubber component in the rubber composition for the inner liner. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5- One or more of di (t-butylperoxy) hexane and the like can be used. Moreover, as a sulfur type vulcanizing agent, 1 type (s) or 2 or more types can be used among sulfur, a morpholine disulfide, etc., for example.

  Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Of these, one or more can be blended.

  As an anti-aging agent, 1 type (s) or 2 or more types can be mix | blended among amine type, a phenol type, an imidazole type, a carbamic acid metal salt, a wax, etc., for example.

  Softeners include process oil, lubricant, paraffin, liquid paraffin, petroleum asphalt, petroleum softener such as petroleum jelly, fatty oil softener such as castor oil, linseed oil, rapeseed oil, coconut oil, beeswax, carnauba wax In addition to waxes such as lanolin, tall oil, sub, linoleic acid, palmitic acid, stearic acid, lauric acid and the like can be blended.

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

  Furthermore, in order to prevent or delay scorch, for example, organic acids such as phthalic anhydride, salicylic acid and benzoic acid, nitroso compounds such as N-nitrosodiphenylamine, N-cyclohexylthiophthalimide and the like can be added as scorch preventing agents.

  The inner liner layer is prepared by kneading the blended components of the rubber composition for the inner liner at 130 ° C. or higher and 160 ° C. or lower with, for example, a Banbury mixer or kneader, and preparing the uncrosslinked product. It can be formed by applying to the liner portion and vulcanization molding.

  The present invention can be applied to various tires for passenger cars, trucks / buses, heavy machinery and the like. FIG. 1 is a cross-sectional view showing a right half of a tire according to the present invention. The 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. 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. An apex 8 is arranged.

[Example]
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Examples 1 to 3, Reference Example 1, Comparative Examples 1 to 4>
Of the blending components shown in Table 1, the components excluding sulfur and the vulcanization accelerator were kneaded at about 140 ° C. for 3 minutes using a banbury. Thereafter, sulfur and a vulcanization accelerator were added and kneaded at about 25 ° C. for 5 minutes using a biaxial open roll. Using the obtained unvulcanized material, a rubber sheet having a thickness of 1 mm is prepared, applied to the inner liner portion of the pneumatic tire, and vulcanized at 170 ° C. for 25 minutes to obtain a 195 / 65R15 size pneumatic tire. It was.

<Air permeability>
The pneumatic tire obtained above is filled with air so that the internal pressure becomes 250 kPa, which is the specified internal pressure, and the degree of decrease in air pressure after running the drum for 100 hours with a 300 kg load is expressed by the following equation:
(Air permeability index) = (Air pressure after drum running of pneumatic tire according to each embodiment (kPa)) / (Air pressure after drum running of pneumatic tire according to Comparative Example 1) × 100
Accordingly, the air permeability index was calculated with Comparative Example 1 as 100. The larger the value, the lower the air permeability and the better the degree of decrease in air pressure. The results are shown in Table 1.

<Tire durability>
The pneumatic tire obtained above is filled with air so that the internal pressure becomes 250 kPa, which is the specified internal pressure, and after running for 30000 km drum with a load of 300 kg, the pneumatic tire is disassembled and the ply cord and rubber at the center in the radial direction are disassembled A peel test was conducted between the two. The peel test was performed according to JIS K6250. From the measured value of the peel force, the degree of tire durability is expressed by the following equation:
(Tire durability index) = (Peeling force in the pneumatic tire according to each example) / (Peeling force in the pneumatic tire according to Comparative Example 1) × 100
Thus, the tire durability index was calculated with Comparative Example 1 as 100. The larger the value, the better the tire durability. The results are shown in Table 1.

Note 1: Chlorinated butyl rubber is “Chlorobutyl 1068” manufactured by Nippon Butyl Co., Ltd.
Note 2: NR is “SML20” made in Malaysia.
Note 3: BR is butadiene rubber “150B” manufactured by Ube Industries.
Note 4: Carbon black is “N660” manufactured by Tokai Carbon Co., Ltd.
Note 5: Mineral oil is “PS32” manufactured by Idemitsu Kosan Co., Ltd.
Note 6: Zinc oxide is “Ginbae” manufactured by Toho Zinc Co., Ltd.
Note 7: Stearic acid is “Koji” manufactured by NOF Corporation.
Note 8: The vulcanization accelerator NS is “Noxeller NS” (compound name: N-oxydiethylene-2-benzothiazole-sulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Note 9: Sulfur is “powder sulfur” manufactured by Karuizawa Refinery.
Note 10: The ethylene-vinyl alcohol copolymer is “Soarnol AT4403” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., and has a molecular structure represented by the aforementioned general formula (I).
Note 11: The compatibilizing agent is a 1,1-dialkylethylene-vinyl alcohol block copolymer manufactured by Nippon Synthetic Chemical Industry Co., Ltd., and has a molecular structure represented by the aforementioned general formula (II).

From the results shown in Table 1, an example in which an inner liner layer comprising a rubber composition for an inner liner containing an ethylene-vinyl alcohol copolymer in a range of 15 to 30 parts by mass with respect to 100 parts by mass of the rubber component was formed. 1 to 3 , Comparative Examples 1 to 3 containing no ethylene-vinyl alcohol copolymer, and Comparative Example 4 having a content of ethylene-vinyl alcohol copolymer as small as 5 parts by mass with respect to 100 parts by mass of the rubber component As compared with, both air permeability index and tire durability index showed good values. Therefore, it can be seen that by using the rubber composition for an inner liner in which a specific ethylene-vinyl alcohol copolymer is blended in the present invention, good durability can be obtained while obtaining an effect of suppressing a decrease in tire air pressure.

  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 that is excellent in the effect of suppressing the decrease in air pressure, durability, and fuel consumption can be suitably applied to various uses such as for passenger cars, trucks / buses, and heavy machinery.

It is sectional drawing which shows the right half of the tire which concerns on this invention.

Explanation of symbols

  1 tire, 2 tread part, 3 sidewall part, 4 bead part, 5 bead core, 6 carcass, 7 belt layer, 8 bead apex, 9 inner liner.

Claims (5)

For 100 parts by mass of a rubber component made of natural rubber and / or synthetic rubber,
The following general formula (I),

(Wherein, m and n are each independently 1 to 100, and x is 1 to 1000)
15-30 parts by mass of an ethylene-vinyl alcohol copolymer represented by
The following general formula (II),

(Wherein R is an alkyl group, p and q are each independently 1 to 100, and y is 1 to 5). A pneumatic tire using the composition as an inner liner layer.   The rubber composition for the inner liner further includes at least one selected from carbon black, silica, and mica within a range of 10 to 80 parts by mass with respect to 100 parts by mass of the rubber component. The described pneumatic tire.   The pneumatic tire according to claim 1, wherein a content of the halogenated rubber in the rubber component is in a range of 60 to 100% by mass.   The pneumatic tire according to claim 1, wherein the rubber composition for an inner liner is crosslinked with sulfur or a peroxide.   2. The pneumatic tire according to claim 1, wherein a thickness of the inner liner layer measured at a tire maximum width position in a state in which a specified internal pressure is filled is in a range of 0.1 to 5 mm.

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