JP2009173048A - Tread and tire using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tread with high productivity excellent in operation stability and wearing resistance while retaining a gripping property, and a tire using it. <P>SOLUTION: For the tread, a rubber composition having a ratio of 300% modulus at 100°C of a portion to 1.0 mm from a surface and 300% modulus at 100°C of a portion of 0.5-1.5 mm at an outer side in a tire radial direction from a bottom surface of 1.1-4.0 and containing 0.5-3 pts.mass of a vulcanizing agent relative to 100 pts.mass of a rubber composition is used. Further, the tire is preferably manufactured by selectively irradiating a surface of the tread with an electron ray after the tread is stuck on a raw tire case and is vulcanized and performing vulcanization after the tread is stuck on the raw tire case and the surface of the tread is selectively irradiated with an electron ray. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tread excellent in handling stability and wear resistance while maintaining grip properties, and having high productivity, and a tire using the tread.

  In order to improve the grip property of the tread, a technique of softening the tread by changing the composition of the rubber composition used for the tread is generally used. However, according to this method, the tread block rigidity is lowered, and thus the steering stability is deteriorated. Further, when a hard rubber layer is provided on the tread surface, there is a problem in that the grip property is remarkably reduced although the block rigidity of the tread is improved.

  In order to solve these problems and simultaneously improve various performances of the tire such as grip performance and steering stability, a method of forming a tread with a two-layer structure including a surface layer and an inner surface layer having different physical properties has been proposed. Specifically, by forming a tread with a two-layer structure of an inner rubber layer and an outer rubber layer whose modulus is 1.2 times that of the inner rubber layer, uneven wear at the initial stage of travel is reduced and ice and snow roads are formed. A technique for improving grip performance during traveling has been proposed (see Patent Document 1). 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, and the tread has two layers whose surface layer is softer than the inner surface layer. A technique for improving grip performance at the initial stage of travel by forming the structure has been proposed (see Patent Document 2). Furthermore, a technique has been proposed in which a specific two-layer tread is used to achieve both wear resistance and grip performance on a wet road surface (see Patent Document 3).

Japanese Unexamined Patent Publication No. 7-117411 Japanese Patent Application Laid-Open No. 2002-079808 JP 2005-523193 A

  However, when a tread having a two-layer structure is formed as described above, it is necessary to uniformly arrange and insert a member having a thickness of 1.5 mm or less in the tread for manufacturing the tire. It is very difficult to arrange and insert the following members uniformly in the manufacturing process, and the profitability is low and it is difficult to put it into practical use. Further, when the high stability rubber is disposed on the tread surface layer as described above to improve the handling stability, the grip rigidity may be remarkably lowered although the block rigidity of the tread is improved.

  Therefore, an object of the present invention is to provide a tread improved in handling stability and wear resistance by increasing the block rigidity of the tread while maintaining grip properties and a tire using the tread with high productivity. .

  As a result of diligent investigations to achieve the above object, the present inventor has found that a 300% modulus at 100 ° C. (hereinafter also referred to as “100 ° C. M300”) of the portion from the surface to 1.0 mm and the tire radial direction from the bottom surface. Ratio of the outer 0.5 mm to 1.5 mm portion with 100 ° C M300 ((100 ° C M300 of the portion from the surface to 1.0 mm) / (the tire radial direction outer side 0.5 mm to 1.5 mm from the bottom surface) The tread is characterized by using a rubber composition having a partial 100 ° C. M300)) of 1.1 to 4.0 and containing 0.5 to 3 parts by mass of a vulcanizing agent with respect to 100 parts by mass of the rubber component The tread that has improved handling stability and wear resistance by increasing the block rigidity of the tread while maintaining grip, and tires using the tread with high productivity It found to be able to test, and have completed the present invention.

  That is, the tread of the present invention has a 300% modulus at 100 ° C. of a portion from the surface to 1.0 mm and a 300% modulus at 100 ° C. of a portion 0.5 mm to 1.5 mm outside in the tire radial direction from the bottom surface. The ratio is 1.1 to 4.0, and a rubber composition containing 0.5 to 3 parts by mass of a vulcanizing agent with respect to 100 parts by mass of the rubber component is used.

  In a preferred embodiment of the tread of the present invention, a rubber composition having the same composition in a portion from the surface to the inner side in the tire radial direction of 1.0 mm and a portion from the bottom surface to the outer side in the tire radial direction from 0.5 to 1.5 mm. Use things.

  In another preferred embodiment of the tread of the present invention, the vulcanizing agent is sulfur.

  In another preferred embodiment of the tread of the present invention, the rubber composition further contains 0.2 to 5 parts by mass of a vulcanization accelerator with respect to 100 parts by mass of the rubber component.

  In another preferred embodiment of the tread of the present invention, the rubber component contains styrene butadiene rubber.

  In another preferred embodiment of the tread of the present invention, the styrene butadiene rubber has a vinyl bond content of 15% or more.

  In another preferred embodiment of the tread of the present invention, the 300% modulus at 100 ° C. of the portion 0.5 mm to 1.5 mm in the tire radial direction from the bottom surface is 1.0 to 12 MPa.

  The tire of the present invention is preferably manufactured by applying the tread according to any one of claims 1 to 7.

  In the tread of the present invention, it is preferable that the portion from the surface to 1.0 mm is vulcanized at a higher temperature than the portion from the bottom surface of the tread to the outer side in the tire radial direction of 0.5 mm to 1.5 mm. . Further, in the tire of the present invention, after attaching the tread to the raw tire case, the portion from the surface to 1.0 mm is more than the portion of the outer side in the tire radial direction from 0.5 mm to 1.5 mm from the bottom surface of the tread. Also, it is preferable to produce by vulcanizing at a high temperature.

  In another preferred embodiment of the tread of the present invention, the tread is produced by irradiation with an electron beam from the surface. Moreover, it is preferable that the tire of the present invention is manufactured by vulcanizing after attaching the tread to the raw tire case.

  In the tire of the present invention, the tread is attached to a raw tire case and vulcanized, and then the surface of the tread is irradiated with an electron beam, or the tread is attached to the raw tire case and the surface of the tread is irradiated with an electron beam. Then, it is preferable to produce by vulcanization.

  In another preferred embodiment of the tread of the present invention, the surface is selectively irradiated with an electron beam. In another preferred embodiment of the tire of the present invention, the tire is manufactured by attaching the tread to a green tire case and then vulcanizing the tire.

  In the tire of the present invention, the tread is attached to the raw tire case and vulcanized, and then the surface of the tread is selectively irradiated with an electron beam, or the tread is attached to the raw tire case and selected on the surface of the tread. It is preferable to produce by vulcanizing after irradiating the electron beam.

  ADVANTAGE OF THE INVENTION According to this invention, the tread which is excellent in steering stability and abrasion resistance, and has high productivity, maintaining a grip property, and a tire using the same can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. 1-3 are partial cross-sectional views of the tread of the present invention.

  As shown in FIGS. 1 to 3, the tread of the tire of the present invention has a 300% modulus at 100 ° C. of a portion (hereinafter also referred to as “surface layer”) 2 from the surface to 1.0 mm, and a radial direction from the bottom surface 5. The ratio of the outer 0.5 mm to 1.5 mm portion (hereinafter also referred to as “bottom layer”) 4 to 300% modulus at 100 ° C. is 1.1 to 4.0, and relative to 100 parts by mass of the rubber component A rubber composition containing 0.5 to 3 parts by mass of a vulcanizing agent is used. Here, as indicated by 2 in FIG. 1, the “surface” is intended to indicate the side surface of the tread block 1 and the surface of the bottom surface of the groove 3 as well as the surface of the tread surface. Yes. Further, the “bottom surface” refers to a surface that contacts the tread case (indicated by 5 in FIGS. 1 to 3). When the modulus ratio between the surface layer and the bottom surface is less than 1.1, sufficient steering stability cannot be obtained, and when it exceeds 4.0, grip performance is remarkably deteriorated. The modulus ratio between the surface layer and the bottom layer is preferably 1.1 to 2.0. Further, when the amount of the vulcanizing agent contained in the rubber composition is 0.5 to 3 parts by mass with respect to 100 parts by mass of the rubber component, by selecting the electron beam irradiation conditions and the vulcanization temperature conditions, It is highly effective in improving handling stability and wear resistance while maintaining grip properties by making treads have desired physical properties. Here, the vulcanizing agent contained in the rubber composition is preferably 1.0 to 2.5 parts by mass, more preferably 1.5 to 2 parts by mass with respect to 100 parts by mass of the rubber component. preferable. Although it does not specifically limit as said vulcanizing agent, Sulfur is preferable from a versatility viewpoint.

  Further, the tread of the present invention has the same compounding in a portion (surface layer 2) from the surface to 1.0 mm and a portion (bottom layer 4) 0.5 to 1.5 mm outside the tire radial direction from the bottom surface 5. It is preferable to use a composition. Thus, when the rubber composition of the same composition is used for the surface layer 2 and the bottom surface layer 4 of the tread of the present invention, the production becomes easy. Moreover, it is preferable that the 300% modulus at 100 ° C. of the portion 4 0.5 mm to 1.5 mm in the tire radial direction from the bottom surface is 1.0 to 12 MPa. Here, if the 300% modulus at 100 ° C. of the bottom layer 4 is less than 1.0 MPa, the steering stability is impaired, and if it exceeds 12 MPa, the grip performance of the tread rubber is not satisfied.

  The rubber composition used for the tread of the present invention preferably further contains 0.2 to 5 parts by mass of a vulcanization accelerator in total with respect to 100 parts by mass of the rubber component. Here, when the amount of the vulcanization accelerator contained in the rubber composition used in the tread of the present invention is less than 0.2 parts by mass in total with respect to 100 parts by mass of the rubber component, the fracture strength and abrasion resistance of the vulcanized rubber The rubber elasticity necessary for the grip property of the vulcanized rubber cannot be obtained when the property is reduced and the amount exceeds 5 parts by mass. The vulcanization accelerator compounded in the rubber composition used in the tread of the present invention is not particularly limited, but bis-2-benzothiazoyl sulfide, mercaptobenzothiazole, di-2-benzothiazolyl disulfide and 4, Thiazoles such as 4'-dimethyl-bis-3-benzothiazolyl sulfide, N-cyclohexyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl-2-benzothiazolylsulfenamide and N- Examples thereof include sulfenamides such as t-butyl-2-benzothiazolylsulfenamide, and guanidines such as diphenylguanidine.

  In the tread of the present invention, the rubber component is not particularly limited, and examples thereof include styrene butadiene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, and polychloroprene rubber, and styrene from the viewpoint of securing desired grip performance. It is preferable that butadiene rubber is contained, and that the vinyl bond content of the styrene butadiene rubber is 15% or more. Here, if the vinyl bond content of the styrene-butadiene rubber is less than 15%, the rigidity of the tread at a high temperature range is lowered, and the effect of the present invention is not sufficient.

  In the tire of the present invention, it is preferable to use the tread. By using the tread, it is possible to provide a tire with improved handling stability by increasing the block rigidity of the tread while maintaining grip. Therefore, the tire of the present invention can be widely applied not only to passenger car tires but also to studless tires, racing tires, bus / truck tires, off-road tires, motorcycle tires, and the like.

  In addition, as a tire member other than the tread, a known member can be used. In addition, the tire of the present invention may be a pneumatic tire or a solid tire. When the tire is a pneumatic tire, the gas filled in the tire of the present invention may be a normal or an oxygen partial pressure adjusted air. In addition, an inert gas such as nitrogen, argon, or helium can be used.

  As an example of the configuration of the tire according to the present invention, the tire includes a pair of bead portions, a carcass connected in a toroidal shape to the bead portions, a belt and a tread for tightening a crown portion of the carcass. It is mentioned that it is a tire. The tire of the present invention may have a radial structure or a bias structure. Moreover, the form of the tread of this invention is not specifically limited, For example, it does not need to have a groove | channel.

  Moreover, in the manufacturing method of the tread of this invention and a tire using the same, as a method for making the said surface layer and the said bottom face layer of the tread of this invention into the said physical property, an electron beam is irradiated to these parts. And vulcanization under specific temperature conditions. Specifically, (1) the part from the surface to 1.0 mm is vulcanized at a higher temperature than the part from 0.5 mm to 1.5 mm outside in the tire radial direction from the bottom surface of the tread, (2) vulcanization After the treatment, only the portion from the surface to 1.0 mm is heated with a high-temperature warmer or the like, (3) a vulcanization accelerator in the rubber composition using a manufacturing method of winding a ribbon-like rubber and molding a tread member, and Examples include adjusting the sulfur content and (4) irradiating an electron beam from the tread surface. However, as shown in FIG. 1, when the entire surface of the tread is cured, the handling stability is improved, but the grip performance may be lowered. Therefore, for example, the electron beam is irradiated by selectively irradiating the side surface of the groove 3 as shown in FIG. 2 and the side surface of the tread block 1 and the bottom of the groove 3 as shown in FIG. Only the irradiated part (indicated by 2 in FIGS. 2 and 3) may have the physical properties. As described above, the method of selectively irradiating each part of the tread with the electron beam includes (5) selectively irradiating the part of the tread rubber with the electron beam and (6) curing the tread rubber. A masking sheet is attached to a portion that is not desired, and the entire surface is irradiated with an electron beam. The desired effect can be obtained by any method. As described above, the timing of heating or vulcanizing the tread at a specific temperature, the timing of irradiating the tread with an electron beam, and the like are as follows. Any time after sulfuration may be used. However, if the tire is manufactured by applying the electron beam to the raw tire case and then vulcanizing the tread, it should be attached to the tire case if the dread is completely vulcanized by electron beam irradiation. Will not be able to. Therefore, in such a production method, it is preferable that the tread is in a semi-vulcanized state after being irradiated with an electron beam.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

(DRY grip measurement method)
The prototype tires were installed in a competition vehicle and run on a dry circuit, and the test driver's feeling during running was evaluated according to the following criteria. In addition, the result of the comparative example 1 was set to “0”, and relative evaluation was performed according to the following criteria. The larger the value, the better the grip.
+3 ・ ・ ・ Amount that a general driver with low driving frequency can clearly recognize the difference +2 ・ ・ ・ Amount that a general driver with high driving frequency can recognize the difference +1 ・ ・ ・ Amount that a professional driver can recognize the difference 0 ・ ・・ Control-1: To the extent that a professional driver can recognize the difference-2 ... To the extent that a general driver with high driving frequency can recognize the difference-3 ... To a general driver with low driving frequency clearly recognizes the difference As much as possible

(Measurement method of steering stability)
The prototype tires were mounted on a racing vehicle and run on a circuit, and the test driver's feeling during running was evaluated according to the following criteria. In addition, the result of the comparative example 1 was set to “0”, and relative evaluation was performed according to the following criteria. The larger the value, the better the steering stability.
+3 ・ ・ ・ Amount that a general driver with low driving frequency can clearly recognize the difference +2 ・ ・ ・ Amount that a general driver with high driving frequency can recognize the difference +1 ・ ・ ・ Amount that a professional driver can recognize the difference 0 ・ ・・ Control-1: To the extent that a professional driver can recognize the difference-2 ... To the extent that a general driver with high driving frequency can recognize the difference-3 ... To a general driver with low driving frequency clearly recognizes the difference As much as possible

(Examples 1-4)
Treads for competition tires were formed from the rubber compositions shown in Tables 1 and 2. After preparing test tires (size: 225 / 40R18) using these treads, the side surface of the tread block 1 shown in 2 of FIG. 3 and the bottom of the groove 3 were irradiated with an electron beam under the conditions shown below. It was. The electron beam irradiation was performed using an apparatus manufactured by “Nisshin High Voltage Company”. Each tire was evaluated for grip properties and steering stability by the above methods. The results are shown in Tables 1 and 2.

* 1 Toughden 4350 manufactured by Asahi Kasei Corporation (styrene content 39%, vinyl bond content 38%, 50% aromatic oil oiled)
* 2 SAF (N ₂ SA = 150 m ² / g)
* 3 Alkylphenol resin * 4 Bis-2-benzothiazolyl sulfide * 5 4,4'-dimethyl-bis-3-benzothiazolyl sulfide * 6 Electron beam irradiation conditions: 150 kGy (acceleration voltage 300 kV)
* 7 Electron beam irradiation conditions: 300 kGy (acceleration voltage 300 kV)
* 8 Electron beam irradiation conditions: 220 kGy (acceleration voltage 300 kV)

  From the results of Tables 1 and 2, when the value of (surface layer 100 ° C. M300) / (bottom layer 100 ° C. M300) of the tread after electron beam irradiation is less than 1.1 (Comparative Examples 1 to 4), steering is performed. The improvement effect of stability is not seen, and when it exceeds 4.0 (Comparative Example 5), although the improvement effect of steering stability is seen, the grip property is lowered, while the electron beam irradiation (100 of the surface layer) is reduced. When the value of (° C. M300) / (100 ° C. M300 of the bottom surface layer) is 1.1 to 4.0 (Examples 1 to 4), an improvement effect is seen in both grip properties and steering stability. Accordingly, the value of (surface layer 100 ° C. M300) / (bottom layer 100 ° C. M300) of the tread after electron beam irradiation is preferably 1.1 to 4.0. From the results of Examples 5 to 8, it can be seen that when the amount of the vulcanizing agent (sulfur) added to the rubber composition is increased, the DRY grip property is lowered and the steering stability tends to be improved.

  In Examples 1 to 3, the tread surface was irradiated with an electron beam after vulcanizing the tire. In Examples 9 to 11, the surface layer was vulcanized at 160 ° C. and the bottom layer was 150 ° C. From the results, it can be seen that any of the treads can have the desired physical properties. Therefore, after the tread is attached to the raw tire case and vulcanized, the tire is manufactured by irradiating an electron beam from the surface of the tread, and after the tread is attached to the raw tire case, 1. It is preferable that the tire is manufactured by vulcanizing a portion up to 0 mm at a higher temperature than a portion of 0.5 mm to 1.5 mm outside in the tire radial direction from the bottom surface of the tread.

It is a fragmentary sectional view of the tread of the present invention. It is a fragmentary sectional view of other embodiments of the tread of the present invention. It is a fragmentary sectional view of other embodiments of the tread of the present invention.

Explanation of symbols

1 Tread block 2 Surface layer 3 Groove 4 Bottom layer 5 Bottom

Claims (15)

  The ratio of the 300% modulus at 100 ° C. of the portion up to 1.0 mm from the surface to the 300% modulus at 100 ° C. of the portion 0.5 mm to 1.5 mm outside in the tire radial direction from the bottom surface is 1.1-4. A tread comprising 0 and a rubber composition containing 0.5 to 3 parts by mass of a vulcanizing agent with respect to 100 parts by mass of a rubber component.   2. The tread according to claim 1, wherein a rubber composition having the same composition is used for a portion from the surface to 1.0 mm and a portion from the bottom surface to the outer side in the tire radial direction by 0.5 to 1.5 mm.   The tread according to claim 1, wherein the vulcanizing agent is sulfur.   The tread according to claim 1, wherein the rubber composition further contains 0.2 to 5 parts by mass of a vulcanization accelerator with respect to 100 parts by mass of the rubber component.   The tread according to claim 1, wherein the rubber component includes styrene butadiene rubber.   The tread according to claim 5, wherein the styrene-butadiene rubber has a vinyl bond content of 15% or more.   2. The tread according to claim 1, wherein a 300% modulus at 100 ° C. of a portion 0.5 mm to 1.5 mm in the tire radial direction from the bottom surface is 1.0 to 12 MPa.   A tire to which the tread according to claim 1 is applied.   2. The tread according to claim 1, wherein a portion from the surface to 1.0 mm is vulcanized at a higher temperature than a portion from 0.5 mm to 1.5 mm outside in the tire radial direction from the bottom surface of the tread. Production method.   After affixing the tread to the raw tire case, the portion from the surface to 1.0 mm is vulcanized at a higher temperature than the portion 0.5 mm to 1.5 mm in the tire radial outer side from the bottom surface of the tread. The tire manufacturing method according to claim 8, wherein   The method for producing a tread according to claim 1, wherein the surface is irradiated with an electron beam.   The tire manufacturing method according to claim 8, wherein the tread manufactured in claim 11 is attached to a green tire case and then vulcanized.   Irradiating the surface of the tread with an electron beam after the tread is attached to the raw tire case, or vulcanizing after applying the electron beam to the surface of the tread after attaching the tread to the raw tire case The tire manufacturing method according to claim 8.   The tire manufacturing method according to claim 8, wherein a tread manufactured by selectively irradiating an electron beam from the surface is attached to a green tire case and then vulcanized.   After the tread is attached to the raw tire case and vulcanized, the surface of the tread is selectively irradiated with an electron beam, or the tread is attached to the raw tire case and the surface of the tread is selectively irradiated with an electron beam. The method for manufacturing a tire according to claim 8, wherein the vulcanization is performed after the vulcanization.

Images