JP5128809B2 - Rain tire - Google Patents

Description

  The present invention relates to a rain tire.

  High performance tires used for racing and the like, particularly rain tires, are required to improve wet grip performance.

  Therefore, generally, a method of blending raw rubber having a high glass transition temperature, silica, and a large amount of softening agent is known. In addition, among butyl-based raw rubbers, it is also known that the effect of improving wet grip performance is very high when a bromide of paramethylstyrene-isobutylene copolymer is used (see, for example, Patent Document 1). ).

  However, a tread containing a bromide of paramethylstyrene-isobutylene copolymer has a drawback that it has poor adhesion to an adjacent rubber and causes a peeling phenomenon during running.

JP 2005-15570 A

  An object of this invention is to provide the rain tire which can balance wet-grip performance and durability in high dimension.

  The present invention relates to (A) a cap tread using a rubber composition for a cap tread containing a rubber component containing 35 to 60% by weight of a brominated product of paramethylstyrene-isobutylene copolymer, and (B) a diene rubber. And a rain tire having a tread having a two-layer structure composed of a base tread using a rubber composition for a base tread that does not contain an amine-based antioxidant.

  The rain tire is preferably for a motorcycle.

  According to the present invention, a rubber composition for a cap tread containing a predetermined amount of a brominated product of paramethylstyrene-isobutylene copolymer is contained in the cap tread, a diene rubber, and an amine antioxidant is not contained. By using the composition for the base tread, a rain tire capable of balancing wet grip performance and durability at a high level can be provided.

  The rain tire of the present invention has a cap tread (A) and a base tread (B).

  The rubber composition for cap tread (hereinafter referred to as rubber composition (A)) used for the cap tread (A) contains a rubber component.

  The rubber component contains a bromide of paramethylstyrene-isobutylene copolymer in order to improve wet grip performance.

  The content of bromide of paramethylstyrene-isobutylene copolymer in the rubber component is 35% by weight or more, preferably 40% by weight or more. If the bromide content of the paramethylstyrene-isobutylene copolymer is less than 35% by weight, the wet grip performance cannot be sufficiently improved by containing the bromide of the paramethylstyrene-isobutylene copolymer. The bromide content of the paramethylstyrene-isobutylene copolymer is 60% by weight or less, preferably 55% by weight or less. When the content of the paramethylstyrene-isobutylene copolymer exceeds 60% by weight, the adhesion between the cap tread (A) and the adjacent rubber (base tread (B)) is inferior. Sex is reduced.

  In addition to the brominated paramethylstyrene-isobutylene copolymer, the rubber component includes natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber ( BR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR) and the like can be used together. Among these, SBR is preferable because it has excellent wet grip performance and adhesion to members inside the tire.

  It is preferable that the rubber composition (A) further contains a filler.

  The filler is not particularly limited, and examples thereof include carbon black, silica, calcium carbonate, alumina, aluminum hydroxide, magnesium oxide, and magnesium hydroxide. Of these, carbon black and silica are preferable.

  The compounding amount of the carbon black is preferably 50 parts by weight or less, more preferably 30 parts by weight or less with respect to 100 parts by weight of the rubber component. When the blending amount of carbon black exceeds 50 parts by weight, wet grip performance tends to deteriorate.

  The amount of silica is preferably 50 parts by weight or more and more preferably 70 parts by weight or more with respect to 100 parts by weight of the rubber component. When the amount of silica is less than 50 parts by weight, wet grip performance tends to deteriorate. The amount of silica is preferably 170 parts by weight or less, and more preferably 150 parts by weight or less. When the amount of silica exceeds 170 parts by weight, the workability during kneading or extrusion tends to deteriorate.

  In addition to the rubber component and the filler, the rubber composition (A) has conventionally been formulated in the tire industry, such as a softener, a silane coupling agent, stearic acid, zinc oxide, sulfur, various additives. A sulfur accelerator or the like can be appropriately blended as necessary. In addition, since the brominated product of paramethylstyrene-isobutylene copolymer has sufficient ozone resistance and weather resistance, it is not particularly necessary to add an antioxidant. In particular, when an amine-based anti-aging agent is blended, the reaction is accelerated by the amine in the anti-aging agent, and the storage stability in the unvulcanized rubber composition may deteriorate.

  The rubber composition for base tread (hereinafter referred to as rubber composition (B)) used for the base tread (B) contains a diene rubber and does not contain an amine antioxidant.

  As the diene rubber, the same diene rubber as that used in combination with the brominated product of paramethylstyrene-isobutylene copolymer in the rubber component in the cap tread (A) can be used. For example, natural rubber (NR ), Isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR) and the like. Among these, SBR is preferable because it is excellent in adhesiveness with the cap tread (A) and adhesiveness with members inside the tire.

  When an amine-based antioxidant is present in the base tread, a cross-linking reaction of a bromide of paramethylstyrene-isobutylene copolymer by the amine-based antioxidant proceeds at the interface between the cap tread (A) and the base tread (B). Therefore, strong vulcanization adhesion between the cap tread (A) and the base tread (B) cannot be obtained during vulcanization.

  In the present invention, by using the base tread (B) containing no amine-based antioxidant as the adjacent rubber of the cap tread (A) containing a bromide of paramethylstyrene-isobutylene copolymer, the conventional paramethylstyrene is used. -The adhesiveness which has been a problem in the tread obtained by using the brominated product of isobutylene copolymer can be improved.

  The amine-based anti-aging agent in the present invention is paramethylstyrene in the rubber composition (A) such as N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine. It is an anti-aging agent using an amine compound capable of crosslinking with a brominated product of an isobutylene copolymer. However, even if amine compounds are used, those that lose the ability to crosslink with bromide of paramethylstyrene-isobutylene copolymer, such as the reaction product of amine and ketone, prevent amine aging. Not an agent.

  As described above, when an amine-based antioxidant is included, the cap tread (A) and the base tread (B) are easily peeled off, which is not preferable. If it is an anti-aging agent other than amine type anti-aging agents such as phenolic type such as quinoline type, phenol type such as 2,6-di-tert-butyl-p-cresol, imidazole type such as 2-mercaptobenzimidazole, etc. However, in order to eliminate the possibility that the amine component remains as an impurity, it is preferable not to add it.

  It is preferable that the rubber composition (B) further contains a filler.

  The filler can be the same as that used in the rubber composition (A), and includes carbon black, silica, calcium carbonate, alumina, aluminum hydroxide, magnesium oxide, magnesium hydroxide and the like. It is done. Of these, carbon black is preferable.

  The compounding amount of carbon black is preferably 50 parts by weight or more, more preferably 60 parts by weight or more with respect to 100 parts by weight of the diene rubber. When the blending amount of carbon black is less than 50 parts by weight, there is a tendency that sufficient hardness as a base tread cannot be obtained. The amount of carbon black is preferably 140 parts by weight or less, and more preferably 120 parts by weight or less. When the blending amount of carbon black exceeds 140 parts by weight, heat generation during running increases, and there is a tendency to cause peeling between the tread and a member inside the tire.

  In the rubber composition (B), in addition to the diene rubber and filler, and if necessary, an anti-aging agent other than amine, a compounding agent conventionally blended in the tire industry, such as a softener, stearic acid Zinc oxide, sulfur, various vulcanization accelerators, and the like can be appropriately blended as necessary.

  The rubber compositions (A) and (B) are produced by a general method. That is, the rubber compositions (A) and (B) can be produced by kneading the compounding agent with a Banbury mixer, a kneader, an open roll, etc., and then vulcanizing.

  The rain tire of the present invention is produced by a usual method using the rubber compositions (A) and (B) as a cap tread and a base tread, respectively. That is, the rubber compositions (A) and (B) are extruded into two layers using, for example, a single-screw extruder to form a two-layer tread shape, and are pasted together with other tire members on the tire molding machine. Together, an unvulcanized tire is formed. The rain tire of the present invention can be manufactured by heating and pressurizing the unvulcanized tire.

  The rain tire here is a tire for running on a wet road surface, for example, in a race.

  The rain tire of the present invention is preferably used for motorcycles because wet grip performance is required.

  The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Styrene butadiene rubber (SBR): Toughden 4350 manufactured by Asahi Kasei Co., Ltd. (styrene content: 40% by weight, containing 50 parts by weight of oil with respect to 100 parts by weight of rubber solid content)
EXXPRO: EXXPRO3745 manufactured by ExxonMobil (brominated product of paramethylstyrene-isobutylene copolymer)
Carbon black: Diamond Black A (N110) manufactured by Mitsubishi Chemical Corporation
Silica: Nipsil VN3 manufactured by Tosoh Silica Corporation
Aroma oil: X-140 manufactured by Japan Energy Co., Ltd.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Anti-aging agent (1): Santoflex 13 (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, amine-based anti-aging agent) manufactured by Flexis
Anti-aging agent (2): Antigen FR manufactured by Sumitomo Chemical Co., Ltd. (A product obtained by purifying a reaction product of an amine and a ketone and having no amine residue, a quinoline-based anti-aging agent)
Anti-aging agent (3): NOCRACK 200 (2,6-di-tert-butyl-p-cresol) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Anti-aging agent (4): Nocrack MB (2-mercaptobenzimidazole) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Stearic acid “paulownia” manufactured by NOF Corporation
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. CBS: Noxeller CZ (N-cyclohexyl- manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) 2-benzothiazolylsulfenamide)
Vulcanization accelerator DPG: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Manufacture of unvulcanized cap tread rubber compositions C-1 to C-4 and unvulcanized base tread rubber compositions B-1 to B-3)
According to the formulation shown in Tables 1 and 2, various chemicals other than zinc oxide, sulfur and a vulcanization accelerator were kneaded at a discharge temperature of 160 ° C. using a Banbury mixer to obtain a kneaded product. Next, zinc oxide, sulfur and a vulcanization accelerator are added to the obtained kneaded product, and kneaded for 4 minutes under the condition of 80 ° C. using an open roll, and rubber composition C-1 for an unvulcanized cap tread. -C-4 and unvulcanized base tread rubber compositions B-1 to B-3 were prepared.

  Tables 1 and 2 show the compositions of the rubber compositions C-1 to C-4 for unvulcanized cap treads and the rubber compositions B-1 to B-3 for unvulcanized base treads.

Examples 1-5 and Comparative Examples 1-5
A tire molding machine comprising a rubber composition for an unvulcanized cap tread shown in Table 3 and a rubber composition for an unvulcanized base tread, which is extruded into two layers using a single-screw extruder and formed into a tread shape. After laminating together with other tire members to form an unvulcanized tire, press vulcanization was performed at 170 ° C. for 20 minutes, and the rain tires (tires) for motorcycles of Examples 1-5 and Comparative Examples 1-5 Size: 195 / 65R420).

(Wet grip performance)
The wet grip performance is obtained by sensory evaluation when the rain tires for motorcycles are mounted on both wheels of the test motorcycle and the circuit on a wet road surface of about 6 km is run for 5 laps under the condition of 20-25 ° C. Judged. In addition, sensory evaluation is performed on a 100-point scale, with Example 1 being 80 points, and a larger value indicates better wet grip performance.

(durability)
The time until delamination at the cap / base interface of the tread portion was measured when the tire was drum-running at a speed of 160 km / h under the condition of 230% load of the maximum load (maximum internal pressure condition) of JIS standard. Then, the measured time was indicated by an index with Example 1 as 80 points. In addition, it shows that durability is so excellent that durability index is large, and the adhesiveness in the cap / base interface of a tread part is excellent.

  The evaluation results are shown in Table 3.

Claims (1)

(A) A cap tread using a rubber composition for cap treads containing a rubber component containing 35 to 60% by weight of a brominated product of paramethylstyrene-isobutylene copolymer, and (B) a diene rubber containing an amine A rain tire for a motorcycle having a tread having a two-layer structure composed of a base tread using a rubber composition for a base tread that does not contain an anti-aging agent.