JP2016216578A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition in which viscosity of an unvulcanized rubber is reduced, processability is improved and wet performance of a tire is enhanced.SOLUTION: There is provided a rubber composition containing: a rubber component (A) containing natural rubber or polyisoprene rubber; and 10 pts.mass to 50 pts.mass of a mixture (B) containing β-pinene and 40 pts.mass to 150 pts.mass of a filler (C) based on 100 pts.mass of the rubber component (A), where the content of the natural rubber or the polyisoprene rubber in the rubber component (A) is 60 mass% or more and the content of the β-pinene in the mixture (B) containing β-pinene is 80 mass% or more.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition and a pneumatic tire.

For example, conventionally, rubber compositions for tire treads have used synthetic rubbers such as butadiene rubber, carbon black, etc., for the purpose of improving grip performance and wear resistance, and their compounding ingredients are derived from petroleum resources. Depended heavily on the raw materials.
Moreover, in the rubber composition for tires, a tackifier is blended for the purpose of improving processability by reducing the viscosity of the rubber composition when it is not vulcanized. Petroleum-based resins such as C9 resins and phenol resins are generally used.

  However, in recent years, environmental issues have become important, and there is a limit to the use of raw materials derived from petroleum resources. Such an environmentally conscious trend is no exception in the tire field, and the development of rubber compositions for tires that replace the petroleum-derived raw materials currently used with raw materials derived from non-petroleum as much as possible is required. ing.

  For example, Patent Document 1 includes a rubber component, at least one of 0.5 parts by mass or more of a terpene resin and a rosin resin with respect to 100 parts by mass of the rubber component, 45 parts by mass or more of silica, A rubber composition for a tread, comprising 5 parts by mass or less of carbon black, wherein the rubber component contains a natural rubber component consisting of at least one of natural rubber and modified natural rubber within a range of 20 to 100% by mass. It is disclosed.

JP 2008-303328 A

  Incidentally, in recent years, from the viewpoint of processability, it is desired to reduce the viscosity of the rubber composition when it is not vulcanized, and also to improve the wet performance of a tire provided with a tread rubber.

  The present invention relates to a rubber composition for reducing the viscosity of an unvulcanized rubber composition from the viewpoint of processability and improving the wet performance of a tire provided with a tread rubber, and a pneumatic tire using the rubber composition. The issue is to provide.

The present invention relates to the following [1] to [3].
[1] A rubber component (A) containing natural rubber or polyisoprene rubber, and a mixture (B) and 40 containing β-pinene of 10 to 50 parts by mass with respect to 100 parts by mass of the rubber component (A) In the rubber composition containing the filler (C) in an amount of 150 parts by weight or more and 150 parts by weight or less,
The content of natural rubber or polyisoprene rubber in the rubber component (A) is 60% by mass or more,
The rubber composition whose content of (beta) -pinene in the mixture (B) containing (beta) -pinene is 80 mass% or more.
[2] A rubber composition in which the glass transition temperature of the rubber having the highest glass transition temperature in the rubber component (A) is −40 ° C. or lower.
[3] A pneumatic tire provided with a tread rubber made of the rubber composition according to [1] or [2].

  According to the present invention, from the viewpoint of processability, a rubber composition that reduces the viscosity of an unvulcanized rubber composition and improves the wet performance of a tire having a tread rubber, and a pneumatic using the rubber composition Tires can be provided.

[Rubber composition]
The rubber composition according to an embodiment of the present invention includes a rubber component (A) containing natural rubber or polyisoprene rubber, and 10 to 50 parts by mass of β-pinene with respect to 100 parts by mass of the rubber component (A). In the rubber composition containing the mixture (B) and 40 to 150 parts by mass of the filler (C), the content of the natural rubber in the rubber component (A) is 60% by mass or more, and the mixture (B ) Content of β-pinene is 80% by mass or more.

<Rubber component (A)>
As the rubber component (A) that can be used in the rubber composition according to the embodiment of the present invention, a rubber containing natural rubber (NR) or polyisoprene rubber (IR) is used.
The other rubber contained in the rubber component (A) includes at least one selected from various synthetic rubbers. Specific examples of the synthetic rubber include styrene / butadiene copolymer rubber (SBR), polybutadiene rubber. (BR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), ethylene-propylene-diene rubber (EPDM), crosslinked polyethylene rubber, chloroprene rubber, nitrile rubber and the like. These rubber components may be used alone or in combination of two or more.
Further, from the viewpoint of reducing the viscosity when the rubber composition is not vulcanized and the wet performance when the tread rubber is used, the rubber having the highest glass transition temperature in the rubber component (A) according to the embodiment of the present invention is used. The glass transition temperature (Tg) is preferably −40 ° C. or lower, more preferably −50 ° C. or lower, and further preferably −60 ° C. or lower.
From the above viewpoint, it is preferable to use a diene rubber such as styrene / butadiene copolymer rubber (SBR) or polybutadiene rubber (BR) as the other rubber.
The content of the natural rubber in the rubber component (A) is 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, from the viewpoint of the mechanical strength of the rubber composition for treads. From this viewpoint, the content is preferably 100% by mass.

<Mixture (B) containing β-pinene>
The mixture (B) containing β-pinene according to the embodiment of the present invention is obtained by extracting β-pinene from a terpene resin, in particular a compound containing 80% by mass or more of β-pinene in the terpene resin. A compound containing a pinene content of 80% by mass or more, or a β-pinene resin.
In addition to β-pinene, the mixture (B) containing β-pinene according to an embodiment of the present invention is α-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-ferrandrene, α-terpinene, γ- Terpinene, terpinolene, 1,8-cineol, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, camphene, tricyclene, sabinene, paramentadienes, and carenes may be included.
The content of β-pinene in the mixture (B) containing β-pinene according to the embodiment of the present invention reduces the viscosity of the rubber composition when it is not vulcanized from the viewpoint of processability, and a tire provided with a tread rubber From the viewpoint of improving the wet performance of the rubber component (A), it is 80% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass of β-pinene resin with respect to 100 parts by mass of the rubber component (A).

<Filler (C)>
It is preferable that content of the filler (C) which concerns on embodiment of this invention is contained 40 mass parts or more and 150 mass parts or less with respect to 100 mass parts of (A) rubber components. By setting the blending amount within this range, it is possible to obtain a sufficient reinforcing effect, prevent exothermic deterioration, and maintain physical properties such as wear resistance and workability. The blending amount is more preferably 20 parts by mass or more and 120 parts by mass or less, and further preferably 30 parts by mass or more and 100 parts by mass or less.

  The rubber composition according to the present embodiment may contain a reinforcing filler. Examples of the reinforcing filler include carbon black, silica, and inorganic compounds represented by the following general formula (IV).

[Chemical 1]
nM · xSiOy · zH ₂ O (I)

  In the formula (I), M is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, an oxide or hydroxide of these metals, and a hydrate thereof, or carbonic acid of these metals. It is at least 1 type chosen from a salt, and n, x, y, and z are the integers of 1-5, the integer of 0-10, the integer of 2-5, and the integer of 0-10, respectively. These reinforcing fillers may be used alone or in combination of two or more.

As carbon black, those usually used in the rubber industry can be used. For example, various grades of carbon black such as SAF, HAF, ISAF, FEF, SRF, and GPF can be used alone or in combination.
Silica is not particularly limited, but wet silica, dry silica, and colloidal silica are preferable. These can be used alone or in combination.

Furthermore, examples of the inorganic compound represented by the general formula (I) include alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina, and alumina monohydrate (Al ₂ O ₃ .H) such as boehmite and diaspore. ₂ O), aluminum hydroxide [Al (OH) ₃ ] such as gibbsite, bayerite, aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), Magnesium carbonate (MgCO ₃ ), talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide ( CaO), calcium hydroxide [Ca _(OH) 2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay (A ₂ O ₃ · 2SiO _2), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H ₂ O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ · 3SiO ₄ · 5H ₂ O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ SiO ₄ etc.) , Aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · _nH 2 O], zirconium carbonate _{[Zr (CO 3) 2]} , the correction charge as various zeolites Hydrogen, and crystalline aluminosilicates containing alkali metals or alkaline earth metals can be used that.
In addition, as the inorganic compound represented by the general formula (I), M is at least one selected from aluminum metal, aluminum oxide, aluminum hydroxide, aluminum hydrate, and aluminum carbonate. Is preferred.
Among these, carbon black, silica and aluminum hydroxide are preferable as the filler.

<Other additives>
In the present embodiment, in addition to the additives described above, compounding agents commonly used in the rubber industry, for example, process oil, anti-aging agent, softener, fatty acid such as zinc oxide, stearic acid, ozone deterioration preventing agent, A colorant, an antistatic agent, a lubricant, an antioxidant, a silane coupling agent, a foaming agent, a foaming aid, and the like can be appropriately blended within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be suitably used.
In addition, when mix | blending a silane coupling agent in a rubber composition, the compounding quantity has preferable 2 mass parts or more and 12 mass parts or less with respect to 100 mass parts of rubber components (A).
Moreover, when mix | blending a fatty acid in a rubber composition, the compounding quantity has preferable 0 mass part or more and 3 mass parts or less with respect to 100 mass parts of rubber components (A).
Moreover, when mix | blending a softener in a rubber composition, the compounding quantity has preferable 0 to 20 mass parts with respect to 100 mass parts of rubber components (A).

[Vulcanized rubber composition]
In addition to the components described above, the rubber composition for tire treads of the present invention generally includes rubber compositions such as vulcanization or crosslinking agents, vulcanization or crosslinking accelerators, various oils, anti-aging agents, and plasticizers. Various additives can be blended, and such additives can be kneaded by a general method to form a composition, which can be used for vulcanization or crosslinking. The blending amounts of these additives can be set to conventional general blending amounts as long as the object of the present invention is not violated.

[Pneumatic tire]
The pneumatic tire of the present invention is produced by a conventionally known method using the tread rubber composition of the present invention. That is, a rubber composition for a tread containing the above-described essential components and other compounding agents blended as necessary is kneaded and extruded in accordance with the shape of the tire tread rubber at an unvulcanized stage. The unvulcanized tire is formed by molding in a normal manner on a tire molding machine together with other members of the tire. The tire of the present invention can be obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

  Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited to these examples. A crosslinked rubber composition was produced by vulcanizing the rubber composition of the specimen, and the specimen rubber was evaluated based on the following evaluation method.

<Examples 1 to 10 and Comparative Examples 1 to 4>
In accordance with the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, the components other than sulfur and vulcanization accelerator were filled so that the filling rate would be 58%, and the rotational speed was 80 rpm. And kneaded for 3 minutes until reaching 160 ° C. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded material in the amounts shown in Table 1, and then kneaded at 80 ° C. for 5 minutes using an open roll, according to each example and each comparative example. A blended unvulcanized rubber composition was obtained.

The details of various blending components used in Examples and Comparative Examples are as follows.
* 1: Natural rubber (NR): SIR (made in Indonesia)
* 2: Polyisoprene rubber (IR2200, manufactured by JSR Corporation)
* 3: Polybutadiene rubber (Nipol BR1220, glass transition temperature: −110 ° C., manufactured by Nippon Zeon)
* 4: SBR: emulsion-polymerized styrene-butadiene rubber (JSR0122 manufactured by JSR Corporation, glass transition temperature: -38 ° C)
* 5: SBR: emulsion-polymerized styrene butadiene rubber (JSR 1723 manufactured by JSR Corporation, glass transition temperature: -56 ° C)
* 6: Carbon black: Asahi # 70 (N330) (Asahi Carbon Corporation)
* 7: Silica: Ultrazil VN3 (manufactured by EVONIK) (BET specific surface area: 175 m ² / g)
* 8: Silane coupling agent: Si266 (manufactured by Degussa)
* 9: Resin synthesis method derived from α-pinene:
In a well-dried flask with a glass cock, dehydrated hexane (Wako Pure Chemical Industries, Ltd.): 11.6 ml, dehydrated dichloromethane (manufactured by the company): 13.0 ml, α-pinene (manufactured by the company): 2 .3 ml was added under a nitrogen stream, stirred to dissolve uniformly, cooled to −78 ° C., and then a Lewis acid EtAlCl ₂ hexane solution (manufactured by Kanto Chemical Co., Inc., concentration: 1.0 mol / l): 1.18 ml was added to initiate the polymerization. The reaction proceeded without gelation in the reaction solution, and after reacting for 1 hour, 10 ml of methanol was added to the reaction solution to stop the reaction. The reaction solution was reprecipitated with methanol, and the precipitate was sufficiently dried to obtain 2.0 g of α-pinene resin.
* 10: β-pinene 70% resin synthesis method:
For the above examples, except that the monomer used was changed to a mixture of β-pinene: 1.6 ml and α-pinene: 0.69 ml, under the same conditions, β-pinene 70% resin: 2.0 g Obtained.
* 11: β-pinene 80% resin synthesis method:
Except for changing the monomer used in the above example to a mixture of β-pinene: 1.8 ml and α-pinene: 0.56 ml, the same conditions were applied except that β-pinene 80% resin: 2.0 g was used. Obtained.
* 12: β-Pinene Resin Synthesis Method For the above Examples, 2.0 g of β-pinene polymer was obtained under the same conditions except that the monomer used was changed to 2.3 ml of β-pinene.
* 13: Stearic acid: Paulownia (Nippon Yushi Co., Ltd.)
* 14: Zinc oxide: Zinc flower (Mitsui Metal Mining Co., Ltd.)
* 15: Oil: NH60 (made by Idemitsu Kosan Co., Ltd.)
* 16: Anti-aging agent: NOCRACK 6C (Ouchi Shinsei Chemical Co., Ltd.) (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine))
* 17: DPG: 1,3-diphenylguanidine: “Noxeller D” manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 18: CZ: CBS (N-cyclohexyl-2-benzothiazolylsulfenamide))
* 19: Vulcanization accelerator: Noxeller NS (Ouchi Shinsei Chemical Co., Ltd.)

  The following tests were conducted on the unvulcanized rubber compositions obtained in the examples and comparative examples. Table 1 also shows the test results.

(Mooney viscosity index)
According to JIS K6300, the Mooney viscosity of the unvulcanized rubber composition was measured at 130 ° C., and the rubber composition of Comparative Example 1 was set to 100 as the reference compounded rubber composition, and the Mooney viscosity was indicated by an index using the following formula. . The larger the Mooney viscosity index, the lower the viscosity and the easier the processing.
Mooney viscosity index = (Mooney viscosity of reference compounded rubber composition) / (Mooney viscosity of rubber composition of the present invention) × 100

(Grip performance)
Using a British potable skid tester, the resistance value of the vulcanized rubber specimen on the wet concrete road surface was measured. Each data is shown as an index with Comparative Example 1 being 100. The larger the value, the larger the resistance value, and the better the grip performance when wet.

[Evaluation results]
From the results shown in Table 1, it can be seen that in the rubber compositions of the examples, the viscosity of the unvulcanized rubber is reduced and the wet performance is improved.

Claims (3)

A rubber component (A) containing natural rubber or polyisoprene rubber, and a mixture (B) containing β-pinene of not less than 10 parts by weight and not more than 50 parts by weight with respect to 100 parts by weight of the rubber component (A) and not less than 40 parts by weight In the rubber composition containing 150 parts by mass or less of the filler (C),
The content of natural rubber or polyisoprene rubber in the rubber component (A) is 60% by mass or more,
A rubber composition, wherein the content of β-pinene in the mixture (B) containing β-pinene is 80% by mass or more.   A rubber composition in which the rubber having the highest glass transition temperature in the rubber component (A) has a glass transition temperature of -40 ° C or lower.   A pneumatic tire provided with the tread rubber which consists of a rubber composition of Claim 1 or 2.