JP2005254946A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having a splice part capable of obtaining the excellent splice adhesive strength even when the tire is formed of a blend system of tread rubber composition which has been hardly adhered. <P>SOLUTION: In the pneumatic tire comprising a tread part, a pair of side wall parts arranged on the inner side in the tire radial direction from both edges of the tread part, and a bead part continuous to the inner side in the tire radial direction of the side wall parts, a rubber sheet 3 of different composition from that of tread rubber 1 is inserted between splice faces 2 of the tread part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to an improved technique for joining splice surfaces (ends) of an unvulcanized tread rubber composition in a molding process, and a splice part (joint part) formed. The present invention relates to a pneumatic tire that prevents or reduces a failure caused by the tire.

  In the production of a pneumatic tire, an unvulcanized tread rubber composition is attached to the outer periphery of the tire body, and both ends thereof are joined together to form an annular shape, followed by vulcanization molding.

  As a method of joining the splice surfaces of the tread rubber composition to each other, the strip-shaped tread extruded from the extrusion molding machine is cut with a cutter to form a splice surface (contact section), and then the splice surfaces are bonded together. In general, a direct method and a cement method in which a rubber cement having excellent adhesiveness is applied to the splice surface, dried, and then bonded are generally known.

  As an improved technique of the former direct method, Patent Document 1 reports that the splice adhesive force (adhesive strength of the joint portion) can be increased by forming the splice surface with a knife heated to 100 to 300 ° C. Yes.

Moreover, as an improvement technique of the latter cement method, Patent Document 2 contains 2 to 30 parts by mass of white carbon and 0.5 to 15 parts by mass of a sulfur-containing organic silicon compound with respect to 100 parts by mass of cement rubber. It has been reported that excellent vulcanization adhesion can be imparted by using a splice cement for a tire tread.
JP 62-189149 A JP-A-5-170975

  In the case of the direct method in which the tread splice surfaces are bonded together as they are, the rubbers of the same type are generally bonded easily, but there are some which are difficult to bond depending on the compounding system of the tread rubber composition. Conventionally, in such a case, the adhesiveness is often improved by using a splice cement. However, in the compounding system of the tread rubber composition, the adhesiveness is lowered by using the splice cement. There was also.

  Therefore, an object of the present invention is to provide a splice portion that can provide excellent splice adhesion even in a blended system of a tread rubber composition that has been difficult to join by a method other than the direct method and the cement method described above. It is in providing the pneumatic tire which has.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above object can be achieved by inserting a rubber sheet not using a solvent into a splice interface instead of a splice cement using a solvent. It came to complete.

  That is, a pneumatic tire according to the present invention includes a tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edge portions of the tread portion, and a bead connected to the inner side in the tire radial direction of the sidewall portion. The pneumatic tire which consists of a part WHEREIN: Between the splice surfaces of the said tread part, the rubber sheet from which a composition differs from a tread rubber is inserted, It is characterized by the above-mentioned.

  The present inventor has found that the low molecular weight polymer in the tread rubber composition causes a decrease in the splice adhesive force, and in the conventional splice cement, the low molecular weight polymer is extracted by the solvent contained therein, resulting in a decrease in the splice adhesive force. As a result of further diligent examination based on such findings, the low molecular weight polymer is diffused by inserting a rubber sheet having a composition different from that of the tread rubber and having no solvent between the splice surfaces, It has been found that the splice adhesion is improved.

  The present invention suitably works in a compounding system in which the tread rubber includes 20 to 100 parts by mass of a low molecular weight polymer having a weight average molecular weight of 5000 to 40000 and 100 to 200 parts by mass of a softening agent with respect to 100 parts by mass of the rubber component. . Similarly, the tread rubber contains styrene butadiene rubber as a rubber component. In particular, the rubber component of the tread rubber is all styrene butadiene rubber, and 10 to 150 parts by mass of carbon black with respect to 100 parts by mass of the rubber component. Suitable for compounding systems.

  The rubber sheet preferably does not contain a low molecular weight polymer having a weight average molecular weight of 5,000 to 40,000, and contains a softening agent in an amount of 100 parts by mass or less with respect to 100 parts by mass of the rubber component. 30-100 mass parts of carbon black is included with respect to 100 mass parts of components. Furthermore, it is suitable when the rubber component of the rubber sheet is styrene butadiene rubber. Furthermore, the thickness of the rubber sheet is preferably 0.2 to 1.0 mm.

  According to the present invention, excellent splice adhesion can be obtained even with a blended system of tread rubber compositions that has been difficult to join so far, and the failure of a pneumatic tire due to the splice portion is prevented or reduced. be able to.

  When pasting the unvulcanized tread rubber composition on the outer periphery of the tire body and joining the two ends to each other, as shown in FIG. 1, the composition differs from the tread rubber 1 between the splice surfaces 2. The rubber sheet 3 is inserted, and then the splice surface 2 of the tread rubber 1 is bonded to both surfaces of the rubber sheet 3 and then vulcanized.

  As the rubber component of the rubber composition of the tread rubber 1 according to the present invention, a rubber component made of diene synthetic rubber, natural rubber, or a mixture thereof can be used. Here, examples of the diene synthetic rubber include polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). Etc. These rubbers may be used alone or in combination of two or more. In order to sufficiently exhibit the effects of the present invention, it is preferable that at least SBR is contained in the rubber component, and all SBR is particularly preferable. As the SBR, those produced by any polymerization method such as an emulsion polymerization method and a solution polymerization method can be used.

  In order to increase the splice adhesion on the tread splice surface 2, the tread rubber 1 is preferably 20 to 100 parts by mass of a low molecular weight polymer having a weight average molecular weight of 5000 to 40000 with respect to 100 parts by mass of the rubber component, and the softening agent is 100 to 100 parts. It shall contain 200 parts by mass.

Examples of the low molecular weight polymer having a weight average molecular weight of 5,000 to 40,000 contained in the tread rubber include styrene butadiene copolymer, styrene olefin copolymer, polybutadiene, polyolefin and the like, and one kind or two or more kinds are combined. It may be included. As the softening agent, aromatic oil, C ₅ resins, mention may be made of C ₉ resins, also a kind, may be included in combination is two or more.

  Similarly, in order to increase the splice adhesion force on the tread splice surface 2, the tread rubber 1 preferably contains 10 to 150 parts by mass of carbon black with respect to 100 parts by mass of the rubber component. Examples of such carbon black include channel black, furnace black, acetylene black, and thermal black depending on the production method, and any of them can be used. One type of carbon black may be used, or two or more types may be used in combination.

  Next, the rubber component of the rubber sheet 3 can be basically the same as the rubber component of the tread rubber 1, and at least SBR is included in the rubber component in order to sufficiently exert the effects of the present invention. It is preferable to contain, especially preferably all SBR.

  The rubber sheet 3 preferably does not contain a low molecular weight polymer having a weight average molecular weight of 5000 to 40000. Moreover, even if it contains, it shall be the quantity in the range which does not prevent the spreading | diffusion of the low molecular weight polymer of a tread rubber. In addition, the rubber sheet 3 preferably does not contain a softener or contains 100 parts by mass or less with respect to 100 parts by mass of the rubber component. Furthermore, the rubber sheet 3 preferably contains 30 to 100 parts by mass of carbon black with respect to 100 parts by mass of the rubber component.

  Furthermore, the thickness of the rubber sheet 3 is preferably 0.2 to 1.0 mm. If the thickness is less than 0.2 mm, sufficient splice adhesion cannot be obtained. On the other hand, if the thickness exceeds 1.0 mm, the performance of the tread rubber may be impaired.

  In the rubber composition of the tread rubber 1 and the rubber sheet 3 according to the present invention, various chemicals usually used in the rubber industry, such as vulcanizing agents and vulcanization accelerators, as long as the object of the present invention is not impaired. Agents, anti-aging agents, anti-scorch agents, other fillers, zinc white, stearic acid, and the like.

  The pneumatic tire of the present invention is manufactured by a normal method using the tread rubber 1 and the rubber sheet 3 according to the present invention. That is, if necessary, the rubber composition according to the present invention containing various chemicals as described above is extruded into a tread member at an unvulcanized stage, and is applied by a normal method on a tire molding machine. The rubber sheet according to the present invention is inserted between the spliced surfaces to form a green tire. The green tire is heated and pressed in a vulcanizer to obtain a tire. The pneumatic tire of the present invention thus obtained has an excellent splice part and can prevent or reduce a failure caused by the splice part.

Hereinafter, the present invention will be described based on examples.
Example A rubber composition for a tread rubber and a rubber composition for a rubber sheet to be inserted between splice surfaces were prepared according to the blending contents (parts by mass) shown in Table 1 below. Next, the tread rubber extrudate obtained by the rubber composition for a tread rubber is pasted on the outer periphery of the tire body, the rubber sheet made of the rubber composition for a rubber sheet is inserted between the splice surfaces, and these are molded. A pneumatic tire (size: 175SR14) was manufactured by vulcanization.

Comparative Example 1
A rubber composition for a tread rubber was prepared according to the same content as in the examples. Next, the tread rubber extrudate obtained by the rubber composition for a tread rubber was pasted on the outer periphery of the tire body, the splice surfaces were directly joined, and these were molded and vulcanized to have the same size as the example. A pneumatic tire was manufactured.

Comparative Example 2
A rubber composition for tread rubber was prepared according to the same blending contents as in the examples. Next, the tread rubber extrudate obtained from the rubber composition for tread rubber was pasted on the outer periphery of the tire body, and the splice surfaces were bonded to each other with splice cement (SBR cement (SBR: JSR Co., Ltd. # 1500, low molecular weight polymer). Is not contained))), and these are molded and vulcanized to produce pneumatic tires of the same size as in the examples.

  A tread was cut out from the manufactured pneumatic tire, and the adhesive strength of the splice part was measured by a peel test at 100 ° C. The obtained results are also shown in Table 1 below.

1) # 1500 manufactured by JSR Corporation
2) Product made by LICON, trade name: LICON100, weight average molecular weight 10,000)
3) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine 4) Dibenzothiazyl disulfide 5) Tetrakis (2-ethylhexyl) thiuram disulfide

  From the measurement results of the adhesive strength shown in Table 1, the pneumatic tire of the example has an extremely high splice adhesive strength as compared with the pneumatic tires of Comparative Examples 1 and 2, and the failure caused by the tread splice portion can be prevented or reduced. I understand that I can do it.

It is a perspective view which shows the rubber sheet inserted between tread splice surfaces.

Explanation of symbols

1 Tread rubber 2 Splice surface 3 Rubber sheet

Claims (8)

In a pneumatic tire comprising a tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edges of the tread portion, and a bead portion continuous on the inner side in the tire radial direction of the sidewall portion,
A pneumatic tire, wherein a rubber sheet having a composition different from that of the tread rubber is inserted between the splice surfaces of the tread portion.   The pneumatic tire according to claim 1, wherein the tread rubber includes 20 to 100 parts by mass of a low molecular weight polymer having a weight average molecular weight of 5000 to 40000 and 100 to 200 parts by mass of a softening agent with respect to 100 parts by mass of the rubber component.   The pneumatic tire according to claim 1, wherein the tread rubber contains styrene butadiene rubber as a rubber component, and 10 to 150 parts by mass of carbon black with respect to 100 parts by mass of the rubber component.   The pneumatic tire according to claim 1, wherein the rubber component of the tread rubber is styrene butadiene rubber.   The pneumatic tire according to claim 1, wherein the rubber sheet does not contain a low molecular weight polymer having a weight average molecular weight of 5,000 to 40,000, and contains 100 parts by mass or less of a softening agent with respect to 100 parts by mass of the rubber component.   The pneumatic tire according to claim 1, wherein the rubber sheet contains 30 to 100 parts by mass of carbon black with respect to 100 parts by mass of the rubber component.   The pneumatic tire according to claim 1, wherein the rubber component of the rubber sheet is styrene butadiene rubber.   The pneumatic tire according to claim 1, wherein the rubber sheet has a thickness of 0.2 to 1.0 mm.

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