JP5878338B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a color layer is formed on the outer side in the width direction of a tire side portion through a barrier layer.

In recent years, a tire in which a color layer for decoration is formed on a tire side such as a sidewall is generally known as a high value-added tire.
However, the color layer has a problem that the oil component, the anti-aging agent, and the like are transferred from the side rubber portion to turn brown. Therefore, various techniques have been developed for the purpose of preventing this discoloration.

  As a method for suppressing discoloration of the color layer, it is common to use butyl rubber (IIR) for the color layer. However, butyl rubber has few double bonds in the molecule, and has poor co-crosslinking properties between the color layer and the adjacent side rubber. Therefore, butyl rubber contains ethylene propylene-diene terpolymer (EPDM) and natural rubber. Durability is enhanced by using a blend rubber blended with the same.

  In addition, as another method for suppressing the color change of the color layer, by providing a predetermined barrier layer between the rubber on the tire side and the color layer, the diffusion of the oil component and the anti-aging agent is suppressed, and the color layer The technology which suppresses discoloration of this.

  For example, Patent Document 1 includes a color layer having a relatively small thickness, durability, and color layer discoloration suppressing effect (contamination resistance) by optimizing the composition of the color layer and the barrier layer. A pneumatic tire is disclosed.

  However, none of the above-described techniques has sufficient stain resistance because the diffusion of contaminants is promoted by increasing the temperature of the barrier layer and the color layer during traveling. Therefore, development of a pneumatic tire capable of effectively suppressing discoloration of the color layer while having good crack resistance is desired.

JP 2006-168616 A

  The present invention is a pneumatic that has good crack resistance and excellent contamination resistance of the color layer by optimizing the barrier layer formed between the rubber and the color layer on the tire side. The object is to provide a tire.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the barrier layer is an oxidized vapor-grown carbon fiber that is a heat dissipation material having a high thermal conductivity and a high affinity with rubber. It has been found that by constituting from a blended rubber composition, the stain resistance of the color layer can be greatly improved compared to conventional products while having good crack resistance, and the present invention has been completed.

The present invention has been made based on such findings, and the gist thereof is as follows.
(1) A pneumatic tire in which a color layer is formed on the outer side in the width direction of the tire via a barrier layer, and the barrier layer includes a non-diene rubber and an oxidized vapor-grown carbon fiber. A pneumatic tire characterized by comprising a rubber composition.
(2) The pneumatic tire according to (1), wherein the vapor-grown carbon fiber is blended in an amount of 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition.
(3) The pneumatic tire according to (1), wherein the vapor-grown carbon fiber has a length of 0.5 to 30 μm and a diameter of 0.04 to 0.4 μm.
(4) The pneumatic tire according to (1), wherein the oxidation treatment is treatment with nitric acid, sulfuric acid, perchloric acid, or a mixture thereof.
(5) The pneumatic tire according to (1), wherein the oxidation treatment is performed with an oxidizing gas.
(6) The pneumatic tire according to (5), wherein the oxidizing gas is at least one selected from ozone, nitric acid gas, nitrous acid gas, sulfuric acid gas, and sulfurous acid gas.
(7) The pneumatic tire according to (1), wherein the oxidation treatment is a physical oxidation treatment.
(8) The pneumatic tire according to (7), wherein the physical oxidation treatment is at least one selected from a corona discharge treatment and a plasma treatment.
(9) The pneumatic tire as described in (1) above, wherein the non-diene rubber is at least one selected from butyl rubber, ethylene propylene rubber, urethane rubber and chlorosulfonated rubber.
(10) The pneumatic tire according to (1) above, wherein the vapor-grown carbon fiber has a thermal conductivity of 1000 to 1500 W / (m · K).

  According to the present invention, it is possible to provide a pneumatic tire that has excellent crack resistance and is superior in contamination resistance of the color layer as compared with a conventional pneumatic tire on which a color layer is formed.

1 is a cross-sectional view in the width direction schematically showing a part of an embodiment of a pneumatic tire of the present invention. It is sectional drawing which expanded and partially showed the part about the barrier layer of the pneumatic tire of this invention.

Hereinafter, the configuration and reason for limitation of the present invention will be described with reference to the drawings.
FIG. 1 is a view schematically showing a state in which a part of a tread is viewed in a cross-section in the width direction with respect to an embodiment of a pneumatic tire of the present invention. FIG. 2 is an enlarged view showing a cross section of the barrier layer of the pneumatic tire of the present invention.

  As shown in FIG. 1, the pneumatic tire according to the present invention has a color layer 30 formed on the outer side in the tire width direction of the tire side portion (here, the side rubber 10 of the sidewall portion 2) via the barrier layer 20. This is a pneumatic tire 1. Here, the said tire side part means the part (part from a tread end to a bead part) located in a side when it sees in the cross section of the width direction of a tire.

And as shown in FIG. 2, this invention is characterized by the said barrier layer 20 containing the vapor-grown carbon fiber 21 oxidized.
By including the vapor-grown carbon fiber 21 which is a heat dissipation material having a high thermal conductivity, the heat generation of the barrier layer 20 can be suppressed and the transmission coefficient can be reduced. It is possible to obtain a pneumatic tire that suppresses intrusion and has excellent contamination resistance. Moreover, since the vapor-grown carbon fiber 21 is subjected to an oxidation treatment, the affinity with rubber is improved, and good crack resistance can be ensured similarly to the conventional pneumatic tire.

(Color layer)
As shown in FIG. 1, the color layer formed in the pneumatic tire of the present invention is a rubber layer 30 formed on the side rubber 10 on the tire side, and is a layer for improving the design of the tire. is there.

  The rubber composition constituting the color layer is not particularly limited, but butyl rubber (IIR), ethylene propylene rubber (EPM), acrylonitrile butadiene rubber (NBR), chlorosulfonated polyethylene from the viewpoint of ensuring contamination resistance. It is preferable to blend a rubber component containing at least one of rubber (CSM) and urethane rubber (U). The component constituting the color layer is preferably an epoxy-based, ester-based, or acrylic-based aqueous or oily component that is generally used as a paint.

  Moreover, about the said rubber component, the other general rubber component for tires can be included suitably. For example, it contains at least one of natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. it can.

  For example, when forming a white rubber layer as the color layer, a white filler is blended. About the compounding quantity, it is preferable to set it as the range of 40-120 mass parts with respect to 100 mass parts of rubber components. In particular, it is preferably 60 parts by mass or more, and preferably 100 parts by mass or less.

  Examples of the white filler include titanium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, clay, and talc. For example, when titanium oxide is used, in addition to contributing as a white filler, the rubber composition is prevented from being deteriorated by ultraviolet rays, and has an effect of improving discoloration resistance and durability.

  When forming a color layer of other colors, instead of the above white filler, or together with the above white filler, a color pigment such as blue, red, yellow, and green is added to, for example, 100 parts by mass of the rubber component. On the other hand, about 0.5-30 mass parts can be mix | blended.

  The rubber composition constituting the color layer can further contain a crosslinking agent, a vulcanization accelerator and the like. As the crosslinking agent, an organic peroxide or a sulfur vulcanizing agent is preferably used, and can be blended within a range of, for example, 0.3 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component.

  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- Di (t-butylperoxy) hexane or the like can be used. Moreover, as a sulfur type vulcanizing agent, sulfur, morpholine disulfide, etc. can be used, for example.

  Examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. It is possible to use those containing at least one of the agents.

  Moreover, in order to improve processability, a softener can also be mix | blended with the said rubber composition. Here, as the softener, petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petroleum jelly, fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil and coconut oil, beeswax In addition to waxes such as carnauba wax and lanolin, tall oil, sub, linoleic acid, palmitic acid, stearic acid, lauric acid and the like can be mentioned.

  Furthermore, plasticizers such as 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), or the like may be used.

  In addition, a scorch inhibitor, for example, an organic acid such as phthalic anhydride, salicylic acid or benzoic acid, a nitroso compound such as N-nitrosodiphenylamine, N-cyclohexylthiophthalimide, or the like is added to the rubber composition to prevent or retard scorch. can do.

  The anti-aging agent is preferably not included in the rubber composition constituting the color layer. This is because it causes discoloration of the color layer.

  Furthermore, it is preferable to mix | blend a silane coupling agent with the rubber composition which comprises the said color layer. The silane coupling agent has an effect of strengthening the bond between the white reinforcing agent such as silica and the rubber component and improving the dispersibility of the white reinforcing agent in the rubber composition. As the silane coupling agent, for example, those having a thiol-based, amine-based or halogen-based functional group can be preferably used alone or in combination of two or more.

  The thickness of the color layer in the tire width direction is not particularly limited, but is preferably in the range of 0.5 to 3.0 mm. If the thickness is less than 0.5 mm, the designability may not be sufficiently secured. On the other hand, if it exceeds 3.0 mm, the production cost increases.

(Barrier layer)
As shown in FIG. 1, the barrier layer formed in the pneumatic tire of the present invention is formed between the side rubber 10 on the tire side and the color layer 30, and the adhesion between the side rubber 10 and the color layer 30 is improved. This is a layer 20 for securing and preventing the anti-aging agent or the like from entering the color layer 30.
And the said barrier layer 20 consists of a rubber composition which mix | blended the oxidation-grown vapor growth carbon fiber 21 which is a thermal radiation material with high heat conductivity and high affinity with rubber | gum. As shown in FIG. 2, by containing the heat dissipation material 21 having a high conductivity, the heat generation of the barrier layer 20 can be suppressed and the transmission coefficient can be reduced. As a result, the contamination component enters the color layer 10. It can be effectively suppressed.

  Here, the vapor grown carbon fiber is a highly crystalline carbon nanofiber synthesized by a phase method. In addition, the thermal conductivity of the vapor-grown carbon fiber is preferably in the range of 1000 to 1500 W / (m · K) from the viewpoint of ensuring higher heat dissipation and improving the contamination resistance. .

  Moreover, it is preferable that 0.1-20 mass parts is contained with respect to 100 mass parts of rubber components of the said rubber composition. When the content of the heat dissipation material is less than 0.1 parts by mass, since the content is small, heat generation of the barrier layer cannot be sufficiently suppressed, and the stain resistance of the color layer may be reduced, If the content exceeds 20 parts by mass, the content is too large, and crack resistance may be reduced.

Although it does not specifically limit about the rubber component of the rubber composition which comprises the said barrier layer, It is preferable that non-diene type rubber | gum is included from the point which ensures contamination resistance. Here, the “non-diene rubber” means a rubber component containing almost no double bonds in the main chain (specifically, 2.5 mol% or less). For example, butyl rubber (IIR), ethylene propylene rubber (EPM, EPDM), urethane rubber (U), silicone rubber (Q), chlorosulfonated rubber (CSM), acrylic rubber (ACM), fluorine rubber (FKM) and the like. It is done.
By including a non-diene rubber as a rubber component, it is possible to secure barrier properties against an anti-aging agent and the like, and as a result, excellent stain resistance of the color layer can be realized.

  Among them, the non-diene rubber constituting the rubber component is at least one of butyl rubber (IIR), ethylene propylene rubber (EPM, EPDM), urethane rubber (U), and chlorosulfonated rubber (CSM). Preferably there is. This is because the barrier property against an anti-aging agent and the like can be secured and the stain resistance of the color layer can be improved, and when it is made of other non-diene rubber, sufficient stain resistance of the color layer cannot be secured. There is a fear.

  In addition, about the said barrier layer, it is not specifically limited about the presence or absence of coloring. For example, when forming a white barrier layer, a white filler is blended, and for other color barrier layers, a colored pigment of a color as necessary is blended. Also, carbon black may be blended in the same manner as the tire side rubber. There is no particular limitation on the blending amount of the filler.

  The rubber composition constituting the barrier layer can further contain a crosslinking agent, a vulcanization accelerator, and the like. As the cross-linking agent, an organic peroxide and a sulfur-based vulcanizing agent are preferably used as in the color layer, and can be blended within a range of, for example, 0.3 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component.

  Examples of vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. It is possible to use one containing at least one of the agents, and among them, it is preferable to use a thiazole-based vulcanization accelerator from the viewpoint of obtaining high adhesion to the tire side rubber. .

  Moreover, in order to improve processability, a softener can also be mix | blended with the said rubber composition. Here, as the softening agent, the same rubber composition as that constituting the color layer can be used. Further, the plasticizer, the scorch inhibitor, and the silane coupling agent are the same as those of the rubber composition constituting the color layer.

  The anti-aging agent is preferably not included in the rubber composition constituting the barrier layer. This is because it causes discoloration of the color layer.

  The thickness of the barrier layer in the tire width direction is not particularly limited, but is preferably in the range of 0.5 to 3.0 mm. If the thickness is less than 0.5 mm, the contamination resistance may not be ensured. On the other hand, if it exceeds 3.0 mm, the production cost increases.

(Rubber on the tire side)
As shown in FIG. 1, the rubber located on the tire side portion is a rubber member 10 for constituting a tire side portion such as a sidewall portion 2 of the pneumatic tire 1. In the pneumatic tire 1 of the present invention, the color layer 30 is formed on the outer side in the tire width direction via the barrier layer 20. The rubber composition constituting the tire side rubber (side rubber 10 in FIG. 1) is not particularly limited, and a rubber composition used for a normal pneumatic tire may be used.

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

(Examples 1-5 and Comparative Examples 1-2)
Using a kneader, the components shown in Table 1, excluding sulfur and the vulcanization accelerator, were kneaded at about 130 ° C. for 3.0 minutes. Thereafter, sulfur and a vulcanization accelerator were added, and the mixture was further kneaded with a biaxial open roll at about 100 ° C. for 2.0 minutes, and then taken out as a sheet composed of a barrier layer and a rubber layer having a predetermined thickness. Sample pieces of each example and comparative example were prepared from the sheet. The vapor growth carbon fiber shown in Table 1 has a thermal conductivity of about 1200 W / (m · K).
In addition, about the vapor growth carbon fiber contained in each sample piece, the oxidation process was given by the method shown in Table 1.

(Evaluation)
(1) Contamination resistance Between the contaminated rubber containing a certain amount of contaminating components and the white rubber, the laminate provided with the sample pieces prepared in each Example and Comparative Example was vulcanized and placed in a 100 ° C constant temperature bath. Contamination resistance was evaluated by measuring the color difference of the white rubber surface before and after 48 hours using a spectrocolorimeter (manufactured by Konica Minolta Co., Ltd.). The evaluation results are shown in Table 1.
In addition, about evaluation of contamination resistance, it shows as a relative value when the contamination resistance of the comparative example 1 is set to 100, and the larger the numerical value, the higher the contamination resistance and the better the result.

(2) Crack resistance After overlapping the barrier rubber and side rubber shown in Table 1, vulcanization was performed to prepare a sample having a total thickness of 4 mm. After that, it was cut to the specified size (50mm x 10mm), and in an atmosphere kept at about 60 ° C imitating actual running temperature, 0-30% uniaxial dynamic fatigue was given and rubber ruptured The evaluation was performed by the number of times until. The evaluation results are shown in Table 1. In addition, when cracks are generated, the crack generation sites are also shown in Table 1.
In addition, about evaluation of each Example and a comparative example, it shows as a relative value when the contamination resistance of the comparative example 1 is set to 100, and a crack resistance is so high that a numerical value is large, and it becomes a favorable result.

* 1 Bromobutyl 2255 manufactured by JSR
* 2 Asahi Carbon # 55-NP
* 3 Noxeller DM-P manufactured by Ouchi Shinsei Chemical Industry
* 4 MXST made by Miyoshi oil and fat

  From the results of Table 1, it was found that Examples 1 to 5 all had good crack resistance and high contamination resistance of the color layer. On the other hand, although it was comparable about each Example about the crack resistance about the comparative example 1, since the vapor growth carbon fiber was not included, it turned out that it is inferior to contamination resistance. About Comparative Example 2, although it was equivalent to an Example about pollution resistance, it turned out that it is inferior to crack resistance since the oxidation process of vapor-grown carbon fiber is not made | formed.

  According to the present invention, it is possible to provide a pneumatic tire that has excellent anti-fouling properties as compared to a pneumatic tire having a conventional color layer while having good crack resistance. As a result, it becomes possible to use a pneumatic tire for a longer period of time, and there is an industrially useful effect.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Side wall part 10 Side rubber 20 Barrier layer 21 Vapor growth carbon fiber 30 Color layer

Claims (10)

A pneumatic tire in which a color layer is formed on the outer side in the width direction of the tire side portion through a barrier layer,
The pneumatic tire is characterized in that the barrier layer is made of a rubber composition containing a non-diene rubber and an oxidized vapor-grown carbon fiber.   2. The pneumatic tire according to claim 1, wherein the vapor-grown carbon fiber is blended in an amount of 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition.   2. The pneumatic tire according to claim 1, wherein the vapor-grown carbon fiber has a length of 0.5 to 30 μm and a diameter of 0.04 to 0.4 μm.   The pneumatic tire according to claim 1, wherein the oxidation treatment is treatment with nitric acid, sulfuric acid, perchloric acid, or a mixture thereof.   The pneumatic tire according to claim 1, wherein the oxidation treatment is performed with an oxidizing gas.   The pneumatic tire according to claim 5, wherein the oxidizing gas is at least one selected from ozone, nitric acid gas, nitrous acid gas, sulfuric acid gas, and sulfurous acid gas.   The pneumatic tire according to claim 1, wherein the oxidation treatment is a physical oxidation treatment.   The pneumatic tire according to claim 7, wherein the physical oxidation treatment is at least one selected from a corona discharge treatment and a plasma treatment. The pneumatic tire according to claim 1, wherein the non-diene rubber is at least one selected from butyl rubber, ethylene propylene rubber, urethane rubber, and chlorosulfonated rubber. 2. The pneumatic tire according to claim 1, wherein the vapor-grown carbon fiber has a thermal conductivity of 1000 to 1500 W / (m · K).

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