JP2008049741A - Pneumatic tire and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of suppressing eccentric wear prone to occur at an early stage of ware while maintaining grip performance. <P>SOLUTION: In the pneumatic tire provided with a tread member 3 with a block section 5 demarcated by a rib groove 4, the 100°C100% modulus of the surface layer of the rib groove 4 is made between or equal to 1.10 times and 2.0 times of that inside the block section 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire suitable for being applied to passenger car tires, studless tires, racing tires, bus / truck tires, off-road tires, motorcycle tires, and the like, and a method for manufacturing the same.

Conventionally, a technique for improving tire performance by forming a tread member with a two-layer structure including a surface layer and an inner surface layer having different physical properties has been proposed. Specifically, by forming the tread member with a two-layer structure in which the hardness of the surface layer is higher than the hardness of the inner surface layer, it is possible to reduce the amount of uneven wear at the initial stage of wear and improve the grip performance when running on icy and snowy roads Has been proposed (see Patent Document 1). In addition, a technique for improving the wear resistance of a tire has been proposed by arranging a reinforced rubber material blended with short fibers at the bottom of a groove formed on the surface of a tread member (see Patent Document 2). Further, by arranging a rubber whose hardness is 5% or more larger than the hardness of the tread rubber on at least one wall surface of the groove extending in the width direction of the tire formed on the surface of the tread member, occurrence of heel and toe wear is suppressed. A technique has been proposed (see Patent Document 3). Further, the ratio of the stress of the rubber composition constituting the surface layer to the stress of the rubber composition constituting the inner surface layer at 300% elongation is 70% or less, that is, the surface layer is softer than the inner surface layer. A technique for improving the grip performance at the initial stage of travel by forming a tread member with a two-layer structure has been proposed (see Patent Document 4).
Japanese Unexamined Patent Publication No. 7-117411 Japanese Patent Laid-Open No. 1-153305 JP-A-11-78414 Japanese Patent Application Laid-Open No. 2002-079808

  When the tread member is formed with a two-layer structure, it is necessary to uniformly arrange and insert a member having a thickness of 1.5 [mm] or less. However, a member having a thickness of 1.5 [mm] or less is uniformly arranged. Since it is very difficult to insert the tire tread member, the tire tread member cannot be manufactured with high productivity. In addition, when the tread member is formed in a two-layer structure, since the rigidity between the surface layer and the inner surface layer is different, another type of uneven wear is likely to occur, in which only hard rubber remains selectively at the end of travel. Furthermore, when the surface layer of the tread member is formed of a member having high hardness, the uneven wear property at the initial stage of running is improved, but conversely, the grip performance of the tire may be significantly lowered.

  The present invention has been made in order to solve the above-mentioned problems, and its object is to provide a pneumatic tire excellent in productivity capable of suppressing uneven wear that tends to occur at the initial stage of wear while maintaining grip performance, and a method for manufacturing the same. Is to provide.

  As a result of intensive studies, the inventors of the present invention have found that the 100 ° C. modulus of the surface layer of the rib groove is 1.10 times or more and 2.0 times or less the 100% modulus of 100 ° C. inside the block portion. As a result, it was found that a pneumatic tire capable of suppressing uneven wear that tends to occur in the early stage of wear while maintaining grip performance can be realized. According to such a pneumatic tire, since it is not necessary to form the tread member with a two-layer structure, the pneumatic tire can be manufactured with high productivity. “100 ° C. and 100% modulus” means the stress of a member when 100% strain is applied to the member in an atmosphere at a temperature of 100 ° C.

  Hereinafter, an internal configuration of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings.

[Internal configuration of pneumatic tire]
As shown in FIG. 1, a pneumatic tire 1 according to an embodiment of the present invention includes a radial carcass (not shown), a highly rigid belt 2 arranged so as to cover the crown portion of the radial carcass, A tread member 3 formed of a rubber composition, which is disposed on the outer peripheral surface of the belt 2 over the entire circumference, is provided as a main component. Further, the outer surface of the tread member 3 is formed in a crown shape that is an arc shape, and the tread member 3 is an outer skin that contacts the road surface of the pneumatic tire 1. Further, a tread pattern is formed on the surface of the tread member 3 by partitioning the block portions 5 by rib grooves 4 extending in the circumferential direction of the pneumatic tire 1.

  The rubber composition forming the tread member 3 is not particularly limited, but it is preferable that the rubber composition contains at least one [1] or more diene rubber component. This rubber composition also includes reinforcing fillers, process oils, anti-aging agents, vulcanization accelerators, vulcanization accelerators such as stearic acid and zinc white, and vulcanizing agents such as sulfur. The compounding agent normally used can be mix | blended suitably. Examples of reinforcing fillers include carbon black, silica, calcium carbonate, titanium oxide, etc., but 20 to 150 parts by weight of HAF, ISAF, SAF grade carbon with respect to 100 parts by weight of the rubber component as a raw material. It is desirable to be black. Examples of the process oil include paraffinic, naphthenic and aromatic oils.

  Although it does not restrict | limit especially as a vulcanization accelerator, Thiazole type, such as mercaptobenzothiazole and dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl Examples thereof include sulfenamides such as 2-benzothiazylsulfenamide and N′-t-butyl-2-benzothiazylsulfenamide, and diphenylguanidines. Moreover, it is preferable that the compounding quantity of a vulcanization accelerator is 0.1-5 weight part with respect to 100 weight part of rubber components. Moreover, it is preferable that the compounding quantity of a vulcanizing agent is 0.5-5.0 weight part with respect to 100 weight part of rubber components.

  In the present embodiment, the 100 ° C. 100% modulus of the surface layer of the rib groove 4 is 1.10 times or more, preferably 1.3 to 1.5 times larger than the 100 ° C. 100% modulus inside the block portion 5. Is formed. In the present specification, the surface layer of the rib groove 4 is a surface layer excluding a portion of the surface layer of the tread member 3 that is in direct contact with the road surface, as shown in FIGS. Although the surface region 3a including part or all of the surface region 3a is shown, the surface region 3a shown in FIG. 2 (a) is desirable from the viewpoint of workability, and preferably the surface region 3a shown in FIGS. 2 (b) to (e). More preferably, it is the surface region 3a shown in FIGS. 2 (b) and 2 (d). Further, when the direction of heel and toe wear is known in advance, the surface region 3a shown in FIGS. 2 (g) to (i) may be used. The 100 ° C. and 100% modulus is the stress when 100% strain is applied to a sample sliced approximately 1 [mm] along the circumferential direction of the pneumatic tire 1 in an atmosphere at a temperature of 100 ° C. Show. The surface layer refers to a layer sliced 1 [mm] from the tire surface in the axle direction. Moreover, the inside indicates a layer obtained by slicing a position of 0.5 to 1.5 [mm] from the lowest layer of the tread layer in the axle direction (however, the wall surface is not included).

  The 100 ° C. modulus at 100 ° C. of the surface layer of the rib groove 4 is 1% of the 100 ° C. modulus at 100 ° C. inside the block portion 5 by applying a rubber curing material such as sulfur or a vulcanization accelerator to the surface layer of the rib groove 4. It can be formed in the size of 10 times or more. The method of applying the rubber curable material is not particularly limited, but various methods such as coating with a film, dissolving the rubber curable material in a solvent and applying it to the surface layer with a brush, spraying the surface layer, etc. The method can be applied. When the surface layer is cured in the vulcanization process, the timing for applying the rubber curable material to the surface layer is any time after the tread member 5 is extruded until the pneumatic tire 1 enters the vulcanizer. Although it becomes a process, when hardening a surface layer in processes other than a vulcanization process, the timing which apply | coats a rubber hardening material to a surface layer may be performed in any process.

  In the present embodiment, only the surface layer of the rib groove 4 is formed such that the 100 ° C. and 100% modulus is 1.10 times larger than the 100 ° C. and 100% modulus inside the block portion 5. In order to simplify the above, the 100 ° C. 100% modulus of the entire surface layer of the tread member 5 may be 1.10 times larger than the 100 ° C. 100% modulus in the block portion 5. However, if the portion of the surface layer of the tread member 3 that is in contact with the road surface becomes too hard, the grip performance at the initial stage of travel is lowered, so the upper limit of the 100 ° C. and 100% modulus of the surface layer of the tread member 3 is 3.0. [MPa] or less is desirable. Further, the pneumatic tire may be formed such that the 100 ° C. and 100% modulus of the surface layer of the rib groove 4 continuously changes toward the inner direction of the pneumatic tire 1.

  Hereinafter, the pneumatic tire according to the present invention will be described more specifically based on examples.

[Example 1]
In Example 1, a control rubber was prepared, and a 10% solution of 2-mercaptobenzothiazole dissolved in acetone was sprayed on the surface layer of the control rubber as a rubber curing material, whereby the 100 ° C. and 100% modulus inside the block part was set to 100. At that time, the 100% modulus at 100 ° C. of the surface layer was adjusted to 105. The rubber curable material was applied to the surface layer of the control rubber so as to have the form shown in FIG. And the tread member of the competition tire was formed using the prepared rubber composition, and the competition tire (size: 225/40 R18) of Example 1 was obtained. In addition,
[Example 2]
In Example 2, when the 100 ° C. modulus at 100 ° C. inside the block portion is set to 100, the same process as in Example 1 is performed except that the 100 ° C. modulus of the surface layer is adjusted to 110, thereby performing the competition for Example 2 I got a tire.

Example 3
In Example 3, when the 100 ° C. modulus at 100 ° C. inside the block portion is set to 100, the same process as in Example 1 is performed except that the 100% modulus at 100 ° C. of the surface layer is adjusted to 130. I got a tire.

Example 4
In Example 4, when the 100 ° C. modulus at 100 ° C. inside the block portion is set to 100, the same process as in Example 1 is performed except that the 100 ° C. modulus at the surface layer is adjusted to 150. I got a tire.

Example 5
In Example 5, when the 100 ° C. modulus at 100 ° C. in the block portion is set to 100, the same treatment as in Example 1 is performed except that the 100 ° C. modulus at the surface layer is adjusted to 300. I got a tire.

Example 6
In Example 6, a racing tire of Example 6 was obtained by performing the same process as in Example 1 except that the rubber-cured material was applied to the surface layer of the control rubber so as to have the form shown in FIG. .

Example 7
In Example 7, when the 100 ° C. modulus at 100 ° C. inside the block portion was set to 100, the same treatment as in Example 6 was performed except that the 100 ° C. modulus at the surface layer was adjusted to 110, and thus for the competition of Example 7 I got a tire.

Example 8
In Example 8, when the 100 ° C. modulus at 100 ° C. in the block portion is set to 100, the same process as in Example 6 is performed except that the 100 ° C. modulus at the surface layer is adjusted to 130, and for the competition of Example 8 I got a tire.

Example 9
In Example 9, when the 100 ° C. modulus at 100 ° C. inside the block portion was set to 100, the same process as in Example 6 was performed except that the 100 ° C. modulus at the surface layer was adjusted to 150. I got a tire.

Example 10
In Example 10, when the 100 ° C. modulus at 100 ° C. inside the block portion was set to 100, the same process as in Example 6 was performed except that the 100 ° C. modulus at the surface layer was adjusted to 300, so I got a tire.

Example 11
In Example 11, the tire for competition of Example 11 was obtained by performing the same process as Example 4 except having apply | coated rubber cured material to the surface layer of control rubber so that it might become a form shown in FIG.2 (g). .

Example 12
In Example 12, a racing tire of Example 12 was obtained by performing the same process as in Example 4 except that the rubber-cured material was applied to the surface layer of the control rubber so as to have the form shown in FIG. .

[Comparative Examples 1, 2, 3]
A tread member for a competition tire was formed using three types of rubber compositions having different values of 100% modulus at 100 ° C. to obtain a competition tire (size: 225/40 R18) of Comparative Examples 1, 2, and 3. .

[Evaluation of grip performance]
By mounting each tire of Examples 1-12 and Comparative Examples 1-3 on a competition vehicle, running on a circuit, and relatively evaluating the feeling of a test driver during running based on the results of Comparative Example 1, The dry (DRY) grip performance of each tire was evaluated. The evaluation results are shown in Tables 1 to 3 below. In addition, the evaluation value shown below shows that it is excellent in dry grip performance, so that it is a positive value and large.

“+3”: To the extent that general drivers with low driving frequency can clearly recognize the difference “+2”: To the extent that general drivers with high driving frequency can clearly recognize the difference “+1”: To the extent that professional drivers can recognize the difference “ "0" ... Control "-1" ... Problem driver can recognize the difference "-2" ... General driver with high driving frequency can clearly recognize the difference "-3" ... General driver with low driving frequency is clear Can recognize the difference

[Evaluation of uneven wear performance]
The tires of Examples 1 to 12 and Comparative Examples 1 to 3 are mounted on a competition vehicle, run on a circuit, and the heel and toe wear after running is evaluated relative to the results of Comparative Example 1 as a reference. Thus, the grip performance of each tire was evaluated. The evaluation results are shown in Tables 1 to 3 above. In addition, the evaluation value shown below shows that it is excellent in uneven wear performance, so that it is a positive value and large.

“+3”: No evidence of heel and toe wear after running “+2”: To the extent that heel and toe wear is clearly less than control “+1”… Heel and toe wear is controlled “0” that can be recognized as being slightly less “control” −1 ”that can be recognized that there is a little more heel and toe wear than control“ −2 ”that heel and toe wear is clearly more than control Recognizable degree "-3" ... Severe uneven wear that the driver can feel while driving [consideration]
As is apparent from Tables 1 to 3, the grip performance of the racing tires of Examples 4, 5, and 10 in which the 100 ° C. modulus at the surface layer is 1.5 times or more of the 100 ° C. modulus at 100 ° C. inside the block is a comparison. Although it was inferior to the grip performance of the competition tire of Example 1, the grip performance of the competition tire of the other Example showed the same value as the grip performance of the competition tire of Comparative Example 1. The uneven wear performance of the racing tires of Examples 1 and 6 in which the 100 ° C. modulus at 100 ° C. of the surface layer is 1.1 times or less than the 100 ° C. modulus of 100 ° C. inside the block portion is the grip of the racing tire of Comparative Example 1. Although the performance was the same, the uneven wear performance of the competition tires of Examples 2 to 5 and 7 to 12 was higher than the uneven wear performance of the competition tires of Comparative Examples 1 and 2. From the above, the grip performance is maintained by setting the 100 ° C 100% modulus of the surface layer of the rib groove to 1.10 times to 1.5 times the 100 ° C 100% modulus inside the block. It was also found that a pneumatic tire capable of suppressing uneven wear that tends to occur in the early stage of wear can be realized.

  As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

It is sectional drawing which shows the internal structure of the pneumatic tire used as embodiment of this invention. It is an expanded sectional view which shows the surface layer of the rib groove | channel shown in FIG.

Explanation of symbols

1: Pneumatic tire 2: Belt 3: Tread member 4: Rib groove 5: Block portion

Claims (2)

  A pneumatic tire including a tread member having a block portion defined by rib grooves, wherein the surface layer of the rib groove has a 100 ° C 100% modulus of 1.10 times the 100 ° C 100% modulus in the block portion. A pneumatic tire characterized by having a size of 2.0 times or less.   A method of manufacturing a pneumatic tire including a tread member having a block section defined by rib grooves, wherein a hardener is applied to the surface layer of the rib groove, whereby the surface layer of the rib groove is 100 ° C 100 ° C. The method of manufacturing a pneumatic tire is characterized in that the% modulus is 1.10 times or more and 2.0 times or less than the 100% modulus at 100 ° C. inside the block portion.

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