JP2014070096A - Rubber composition for tire, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire, which can improve high mileage, wear resistance, wet grip performance and processability while problems about depletion of fossil resources or environments can be taken into consideration, and to provide a pneumatic tire using the composition.SOLUTION: The rubber composition for a tire includes a resin derived from trees belonging to Hamamelidaceae. The trees belonging to Hamamelidaceae are trees belonging to Hamamelis or Liquidamber. The trees belonging to Liquidamber are at least one species of trees selected from the group consisting of Liquidamber styraciflua, Liquidamber orientalis and Liquidamber formasana. The resin includes at least one compound selected from the group consisting of styrene and styrene derivatives. The resin includes at least one compound selected from the group consisting of β-caryophyllene, α-pinene and β-pinene.

Description

The present invention relates to a rubber composition for tires and a pneumatic tire using the same.

Conventionally, a resin is blended in a tire rubber composition for various reasons such as improvement of grip performance. For example, Patent Document 1 discloses a technique for improving workability, wet grip performance, fracture strength, wear resistance, and steering stability by blending a polystyrene resin. However, most of the resin blended in the tire rubber composition is manufactured from petroleum. Therefore, these resins may be difficult to obtain in the future when the fossil resources are depleted, and there are also problems in terms of environmental considerations.

On the other hand, Patent Document 2 discloses a technique for blending a natural rosin-derived resin into a tire tread composition as a blend of a naturally-derived resin. However, there is a balance between low fuel consumption and wet grip performance. There is room for improvement in processability. Similarly, Patent Document 3 discloses a technique of blending a naturally-occurring terpene resin into a side wall, but although improvement in tear strength and flex crack growth resistance is seen, fuel efficiency and wear resistance are improved. There is room for improvement in wet grip performance and workability. In particular, low fuel consumption and wet grip performance are contradictory, and it is generally difficult to achieve both.

JP 2011-94012 A JP 2004-137463 A JP 2007-197676 A

The present invention solves the above-mentioned problems, can take into account the depletion of fossil resources and the environment, and can improve fuel efficiency, wear resistance, wet grip performance, and workability, and a rubber composition for tires and pneumatic using the same The object is to provide a tire.

As a result of intensive studies, the inventor has surprisingly reduced fuel consumption, wear resistance, wet grip performance, and processability by blending a resin derived from a tree belonging to the witch hazel family into a rubber composition for tires. I found that it can be improved. That is, this invention relates to the rubber composition for tires containing resin derived from the tree which belongs to the witch hazel family.

It is preferable that the tree belonging to the witch hazel family is a tree belonging to the genus Hawthorn or the genus Fusu.

It is preferable that the tree belonging to the genus Fusara is at least one kind of tree selected from the group consisting of Liquidamba styraciflua, Liauidaber orientalis, and Liaudamber formasana.

It is preferable that the resin contains at least one selected from the group consisting of styrene and styrene derivatives.

The resin preferably contains at least one selected from the group consisting of β-caryophyllene, α-pinene, and β-pinene.

It is preferable that the resin contains at least one selected from the group consisting of styrene, styrene derivatives, β-caryophyllene, and α-pinene.

The styrene derivative is at least selected from the group consisting of cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and compounds in which a hydrogen atom bonded to the benzene ring of styrene is substituted with a polar functional group. One type is preferable.

The styrene derivative is selected from the group consisting of cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and compounds in which a hydrogen atom bonded to the 4-position carbon atom of styrene is substituted with a polar functional group It is preferable that it is at least one kind.

The tire rubber composition preferably contains silica.

The present invention also relates to a pneumatic tire using the rubber composition.

According to the present invention, since it is a rubber composition for tires containing a resin derived from a tree belonging to the witch hazel family, it can be considered for depletion of fossil resources and the environment, low fuel consumption, wear resistance, wet grip performance, workability By using the rubber composition for each member of the tire, a pneumatic tire excellent in low fuel consumption, wear resistance, and wet grip performance can be provided.

The rubber composition for tires of the present invention contains a resin derived from a tree belonging to the witch hazel family. In the present specification, the resin means a mixture of solid or semi-solid at room temperature derived from a tree belonging to the family Hazelaceae, and includes a concept of sap.

The composition of the resin derived from trees belonging to the witch hazel family varies depending on the tree type, season, etc., and the detailed composition is not clear, but cinnamic acid, cinnamic ester, cinnamyl alcohol, cinnamaldehyde, styrene, caryophyllene , Pinene and the like are included (Pesticide Biochemistry, 93, 138-143, 2009). And by mix | blending this resin, low-fuel-consumption property, abrasion resistance, wet grip performance, and workability can be improved. This is because the above components contained in the resin are kneaded with a rubber component or the like, and the polymer (adhesive resin) is produced by a) condensation (polymerization), resulting in wet grip performance. Improvement, b) By graft polymerization or addition to the rubber component, polar groups are introduced into the rubber component, dispersibility of reinforcing fillers such as silica is improved, and fuel efficiency and wear resistance are improved. C) It is presumed that it reacts with a reinforcing filler such as silica to improve the dispersibility of the reinforcing filler such as silica and improve fuel efficiency and wear resistance.

On the other hand, when the above-mentioned components contained in the resin are individually blended into the rubber composition, these components do not disperse well in the rubber composition due to immediate self-condensation, thereby improving performance. Is small. On the other hand, in the resin, the component is stably present as a monomer, and it is estimated that the component reacts after the resin is dispersed to some extent in the rubber composition during kneading. The reason for this is unknown, but it is assumed that the resin contains a natural stabilizing component.

Moreover, since the resin derived from the tree belonging to the witch hazel family is naturally derived, it can consider depletion of fossil resources and the environment.

Examples of rubber components that can be used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), and ethylene propylene diene rubber ( EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), diene rubber such as butyl rubber (IIR). A rubber component may be used independently and may use 2 or more types together. Among these, BR and SBR are preferable because wet grip performance and wear resistance can be obtained in a balanced manner, and BR and SBR are more preferably used in combination.

It is not particularly limited as BR, for example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B having high cis content such as BR150B, VCR412 manufactured by Ube Industries, Ltd., VCR617, etc. BR containing syndiotactic polybutadiene crystals can be used. Among them, the BR cis content is preferably 90% by mass or more because good wear resistance can be obtained.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more. The BR content is preferably 40% by mass or less, more preferably 30% by mass or less. When the BR content is within the above range, low fuel consumption, wear resistance, and wet grip performance can be obtained in a well-balanced manner.

The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) and the like can be used.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more. If it is less than 5% by mass, sufficient wet grip performance tends to be not obtained. The styrene content is preferably 50% by mass or less, more preferably 40% by mass or less. When it exceeds 50 mass%, there exists a tendency for abrasion resistance to fall. In the present invention, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The content of SBR in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more. The SBR content is preferably 95% by mass or less, more preferably 90% by mass or less. When the content of SBR is within the above range, low fuel consumption, wear resistance, and wet grip performance can be obtained in a well-balanced manner.

The rubber composition of the present invention contains a resin derived from a tree belonging to the witch hazel family.

Although it does not specifically limit as a tree which belongs to the witch hazel family, the tree which belongs to the genus genus or Fusu genus is preferable, and the tree which belongs to Fu genus is more preferable.

The tree belonging to the genus Witch is not particularly limited.

The tree belonging to the genus Fusu is not particularly limited, but is preferably at least one kind of tree selected from the group consisting of Liquidamber styracifura, Liauidaber orientalis, and Liuidaberma formasana.

As a method for producing a resin derived from a tree belonging to the witch hazel family, it is not particularly limited.For example, a method of obtaining a resin that has damaged and exuded a tree trunk or bark, a trunk, a branch, a leaf, etc. Examples of the method include extraction by a method such as steam distillation, solvent extraction, and the like after removing the solvent. Similarly, all methods of collecting rosin resin, which is a product from trees (tall rosin collection method, gum rosin collection method, wood rosin collection method) can be preferably applied. Among them, a method of obtaining a resin exuded by damaging a tree trunk or bark is preferable because a desired resin can be directly obtained in large quantities and repeatedly collected from a single tree.

In addition, resins derived from trees belonging to the witch hazel family, especially trees belonging to the genus Fusarium, are distributed for aroma use and may be used.

Trees belonging to the witch hazelaceae are widely distributed in the world as street trees and horticultural varieties, and it is preferable to use resins produced by these trees from the viewpoint of environmental considerations. Furthermore, it is possible to effectively use unnecessary trunks, branches, etc. generated at the time of logging, and there is no competition with food products, making it an ideal biomass resource.

As described above, the composition of the resin varies depending on the type of tree, season, etc., and the detailed composition is not clear, but the resin is at least one selected from the group consisting of styrene and styrene derivatives. It is preferable that a styrene derivative is included. These compounds (styrenes) can be polymerized with the same compound and / or with other compounds, and a polymer is produced while being dispersed in rubber during kneading, and as a tacky resin, the tire grip characteristics are improved. It is presumed to improve. In addition, styrenes can be graft-polymerized or added to the diene rubber component during kneading, and as a result, rubber properties (especially low fuel consumption and wear resistance) can be improved. Is done.

Examples of the styrene derivative include cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and compounds in which a hydrogen atom bonded to the benzene ring of styrene is substituted with a polar functional group.

Examples of the polar functional group include a hydroxyl group, a carboxyl group, an ester group, an ether group, an amino group, a sulfide group, a thiol group, and a sulfonic acid group. Of these, a hydroxyl group is preferred.

Cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and compounds in which the hydrogen atom bonded to the benzene ring of styrene is substituted with a polar functional group are not particularly limited, but the carbon atom at the 4-position of these compounds A compound in which the hydrogen atom bonded to is substituted with a polar functional group is preferable.

Specific examples of the compound include, for example, 4-hydroxycinnamic acid, 4-hydroxycinnamic ester, 4-hydroxycinnamyl alcohol, 4-hydroxycinnamaldehyde, 4-hydroxystyrene, 4-carboxycinnamic acid, 4-carboxy. Cinnamic acid ester, 4-carboxycinnamyl alcohol, 4-carboxycinnamaldehyde, 4-carboxystyrene, etc. are mentioned. Of these, 4-hydroxycinnamyl alcohol and 4-hydroxycinnamaldehyde are preferable, and 4-hydroxycinnamyl alcohol is more preferable.

As the styrene derivative, cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and these compounds and compounds in which a hydrogen atom bonded to the 4-position carbon atom of styrene is substituted with a polar functional group are preferable. , Cinnamic acid ester, cinnamyl alcohol, and compounds in which the hydrogen atom bonded to the 4-position carbon atom of these compounds is substituted with a polar functional group, cinnamic acid, cinnamic acid esters, cinnamyl alcohol, 4 -More preferred is hydroxycinnamyl alcohol, and cinnamic acid and cinnamic acid esters are particularly preferred.
The cinnamic acid esters mean cinnamic acid esters and compounds in which the hydrogen atom bonded to the benzene ring of the compound (particularly the hydrogen atom bonded to the 4-position carbon atom) is substituted with a polar functional group. .

The total content of styrene and styrene derivatives (preferably the content of styrene derivatives) in 100% by mass of the resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, particularly Preferably it is 40 mass% or more, Most preferably, it is 60 mass% or more. The total content is preferably 90% by mass or less, more preferably 80% by mass or less.

The resin preferably contains at least one selected from the group consisting of β-caryophyllene, α-pinene, and β-pinene, preferably contains β-caryophyllene and α-pinene, and α-pinene. It is more preferable to contain. These compounds improve processability and can be polymerized with the same compound and / or with other compounds, and form a polymer while being dispersed in rubber during kneading. It is estimated that the grip characteristics are improved.

The total content of β-caryophyllene, α-pinene and β-pinene in 100% by mass of the resin is preferably 0.5% by mass or more, more preferably 1% by mass or more. The total content is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 4% by mass or less.

The resin preferably includes at least one selected from the group consisting of styrene, styrene derivatives, β-caryophyllene, and α-pinene, more preferably includes a styrene derivative, and includes a styrene derivative and α-pinene. , Β-caryophyllene is more preferable, and styrene derivatives, styrene, α-pinene, and β-caryophyllene are particularly preferable. Thereby, the effect of this invention is acquired suitably.
At this time, the content of the styrene derivative in 100% by mass of the resin is preferably 10 to 90% by mass, more preferably 60 to 80% by mass, and the content of styrene in the 100% by mass of the resin is 0.5 to 10%. % By mass is preferable, 0.5 to 5% by mass is more preferable, and the content of α-pinene in 100% by mass of the resin is preferably 0.5 to 10% by mass, and more preferably 0.5 to 5% by mass. The content of β-caryophyllene in 100% by mass of the resin is preferably 0.5 to 10% by mass, and more preferably 0.5 to 5% by mass.
The total content of cinnamic acid and cinnamic acid esters in 100% by mass of the resin is preferably 20 to 80% by mass, more preferably 55 to 75% by mass, and the content of cinnamyl alcohol in 100% by mass of the resin. The amount is preferably 0.5 to 20% by mass, more preferably 0.5 to 5% by mass, and the content of 4-hydroxycinnamyl alcohol in 100% by mass of the resin is preferably 0.5 to 40% by mass. 0.5-10 mass% is more preferable.

The content of the resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, sufficient fuel economy, wear resistance, and wet grip performance tend not to be obtained. The content of the resin is preferably 100 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. When it exceeds 100 parts by mass, the breaking strength and the wear resistance tend to be lowered.

Among the reinforcing fillers, the resin is particularly effective in improving the dispersibility of silica, and therefore the rubber composition of the present invention preferably uses silica. Thereby, low fuel consumption and wet grip performance can be improved, and an effect of improving wear resistance can be obtained. Examples of silica include dry method silica (anhydrous silicic acid), wet method silica (hydrous silicic acid), and the like. Of these, wet silica is preferred.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 m ² / g or more, more preferably 100 m ² / g or more, and further preferably 150 m ² / g or more. If it is less than 50 m ² / g, sufficient reinforcing properties cannot be obtained, and sufficient wear resistance tends to be not obtained. Further, N ₂ SA of silica is preferably 250 m ² / g or less, more preferably 200 m ² / g or less. When it exceeds 250 m < ² > / g, the viscosity of an unvulcanized rubber composition will become high and there exists a tendency for workability to deteriorate. In addition, dispersibility tends to deteriorate, and fuel economy and wear resistance tend to decrease.
The _N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-81.

The content of silica is preferably 5 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is less than 5 parts by mass, there is a tendency that sufficient fuel economy and wet grip performance cannot be improved. The content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and still more preferably 80 parts by mass or less. If it exceeds 150 parts by mass, the dispersibility tends to deteriorate, and the fuel efficiency and wear resistance tend to decrease.

The rubber composition of the present invention preferably uses a silane coupling agent in combination with silica. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. For example, sulfide systems such as bis (3-triethoxysilylpropyl) tetrasulfide, 3 -Mercapto type such as mercaptopropyltrimethoxysilane, vinyl type such as vinyltriethoxysilane, amino type such as 3-aminopropyltriethoxysilane, glycidoxy type of γ-glycidoxypropyltriethoxysilane, 3-nitropropyltri Examples thereof include nitro compounds such as methoxysilane and chloro compounds such as 3-chloropropyltrimethoxysilane. These may be used alone or in combination of two or more. Among these, sulfide type is preferable, and bis (3-triethoxysilylpropyl) tetrasulfide is more preferable.

The content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of silica. If the amount is less than 2 parts by mass, the wear resistance and fuel efficiency tend to deteriorate. Further, the content of the silane coupling agent is preferably 15 parts by mass or less, more preferably 12 parts by mass or less. When it exceeds 15 parts by mass, there is a tendency that an effect commensurate with the increase in cost cannot be obtained.

The rubber composition of the present invention preferably contains carbon black. By blending carbon black, a reinforcing effect is obtained, and the effects of the present invention (particularly, the effect of improving wear resistance and wet grip performance) are obtained more favorably.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 10 m ² / g or more, and more preferably 20 m ² / g or more. If it is less than 10 m ² / g, sufficient reinforcement cannot be obtained, and there is a possibility that sufficient wear resistance and wet grip performance may not be obtained. The _N 2 SA is preferably from ^{80 m} 2 / g or less, more preferably ^{50 m} 2 / g. If it exceeds 80 m ² / g, it becomes difficult to disperse, and the fuel economy and processability tend to deteriorate.
Incidentally, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

The content of carbon black is preferably 5 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 parts by mass, sufficient wear resistance and wet grip performance may not be obtained. The content is preferably 70 parts by mass or less, more preferably 50 parts by mass or less. If it exceeds 70 parts by mass, the dispersibility tends to deteriorate, and the workability, fuel efficiency, and wear resistance tend to deteriorate.

The reinforcing filler other than silica and carbon black that can be used in the present invention can be used without limitation as long as it is publicly used in tire rubber compositions, such as aluminum hydroxide, clay, calcium carbonate. , Montmorillonite, cellulose, glass balloon, various short fibers, and the like. These may be used alone or in combination of two or more.

The rubber composition of the present invention preferably contains a softening agent. The softening agent is not particularly limited, and examples thereof include mineral oils such as aroma oil, naphthenic oil, and paraffin oil. Of these, aroma oil (aromatic process oil) is preferable. These softeners may be used alone or in combination of two or more. The compounding amount of the softening agent is preferably 5 to 50 parts by mass, more preferably 15 to 40 parts by mass with respect to 100 parts by mass of the rubber component. In the present specification, the content of the softening agent includes the amount of oil contained in the oil-extended rubber.

In addition to the above components, the rubber composition of the present invention includes compounding agents commonly used in the production of rubber compositions, such as zinc oxide, stearic acid, various anti-aging agents, tackifiers, waxes, sulfur and the like. Vulcanizing agents, vulcanization accelerators and the like can be appropriately blended.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing. The rubber composition is used for each member of a pneumatic tire (for example, a tread, a sidewall, a base tread, a breaker, a carcass, etc.), and can be particularly suitably used for a tread.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of each tire member such as a tread at an unvulcanized stage, and is molded together with the other tire members by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

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

<Production Example 1>
By exfoliating the bark of Liauidaber orientalis (produced in Japan), the exuded resin was collected and Resin 1 was obtained. Table 1 shows the results (resin composition) obtained by dissolving the resin in ethanol, filtering, and analyzing the solution with a gas chromatograph mass spectrometer (GC / MS).

<Production Example 2>
Resin 2 was obtained in the same manner as in Production Example 1, except that Liquidamba styraciflua (produced in Japan) was used. Table 1 shows the results (resin composition) of the resin 2 analyzed in the same manner as the resin 1.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
SBR: NS116 manufactured by JSR Corporation (vinyl content: 60% by mass, styrene content: 20% by mass)
BR: Polybutadiene rubber manufactured by Ube Industries, Ltd. (UBEPOL BR150B, cis content: 97% by mass)
Resins 1 and 2: Resins prepared according to Production Examples 1 and 2 above (resins derived from trees belonging to the witch hazel family)
Resin 3: YS resin PX1150N (pinene polymer) manufactured by Yasuhara Chemical Co., Ltd.
Oil: Process X-140 (aromatic process oil) manufactured by Japan Energy
Silica: Ultrasil VN3 (N ₂ SA: 175 m ² / g) manufactured by EVONIK-DEGUSSA
Carbon black: Niteron # 55S (N ₂ SA: 28 m ² / g) manufactured by Shin-Nikka Carbon Co., Ltd.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Stearic acid: Stearic acid “paulownia” manufactured by NOF Corporation
Zinc oxide: Zinc oxide type 2 anti-aging agent manufactured by Mitsui Mining & Smelting Co., Ltd .: NOCRACK 6C (N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

Examples and Comparative Examples In accordance with the formulation shown in Table 2, using a 1.7L Banbury mixer manufactured by Kobe Steel, Inc. so that the filling rate is 58% for chemicals other than sulfur and a vulcanization accelerator. It was filled and kneaded at 80 rpm until reaching 140 ° C. to obtain a kneaded product.
Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was molded into a predetermined size, and a vulcanized rubber composition was obtained by press vulcanization at 150 ° C. for 20 minutes, and a vulcanization of about 2 mm × 130 mm × 130 mm was obtained. A rubber slab sheet was prepared and used as a test sample.
Further, the obtained unvulcanized rubber composition was molded into a tread shape, bonded together with other tire members on a tire molding machine, press vulcanized at 170 ° C. for 15 minutes, and a test tire (tire Size: 215 / 45R17) was obtained.

When a 1 cm square sample sheet was cut out from the test sample, the sample sheet was immersed in toluene for 2 days, and the obtained toluene solution was analyzed by GC / MS, the components derived from resins 1 and 2 shown in Table 1 were obtained. It was found that almost all the amount was polymerized or graft-polymerized or added to the rubber component.

The following evaluation was performed using the obtained test sample and test tire. Each test result is shown in Table 2.

<Processability>
Based on JIS K6300-1, Mooney viscosity (ML _{1 + 4} ) was measured at 130 ° C., and the Mooney viscosity of Comparative Example 1 was taken as 100, and the workability index was calculated from the following formula. The larger the index, the better the processability when unvulcanized.
(Processability index) = (Mooney viscosity of Comparative Example 1) / (Mooney viscosity of each formulation) × 100

<Viscoelasticity test>
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, the loss tangent (tan δ) of the test sample was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of ± 1%, and a frequency of 10 Hz. The rolling resistance index of Comparative Example 1 was set to 100, and the rolling resistance was indicated by an index according to the following formula. The larger the rolling resistance index, the lower the rolling resistance and the better the fuel efficiency.
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

<Wet grip performance>
Each test tire was mounted on all wheels of a vehicle (domestic FF2000cc), and a braking distance from an initial speed of 100 km / h was determined on a wet asphalt road surface. The braking distance of Comparative Example 1 was set to 100, and the wet grip performance was displayed as an index according to the following formula. A larger index indicates better wet grip performance.
(Wet grip performance) = (Brake distance of Comparative Example 1) / (Brake distance of each formulation) × 100

<Abrasion resistance>
Using a Lambourne abrasion tester manufactured by Iwamoto Seisakusho, the amount of abrasion of the test sample was measured at a surface rotation speed of 50 m / min, an additional load of 3.0 kg, a sandfall of 15 g / min and a slip rate of 20%. . The wear amount of Comparative Example 1 was divided by the wear amount of each formulation and multiplied by 100 to obtain the wear resistance index. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
(Abrasion resistance index) = (Abrasion amount of Comparative Example 1) / (Abrasion amount of each formulation) × 100

Examples including resins (resins 1 and 2) derived from a tree belonging to the witch hazel family were able to improve fuel efficiency, wear resistance, wet grip performance, and processability.

Claims (10)

A rubber composition for tires comprising a resin derived from a tree belonging to the witch hazel family. The tire rubber composition according to claim 1, wherein the tree belonging to the witch hazel family is a tree belonging to the genus Hawthorn or the Fucus genus. The tire rubber composition according to claim 2, wherein the tree belonging to the genus Fuyu is at least one kind of tree selected from the group consisting of Liquidamber styraciflua, Liauidaber orientalis, and Liauidaber formasana. The tire rubber composition according to any one of claims 1 to 3, wherein the resin includes at least one selected from the group consisting of styrene and a styrene derivative. The tire rubber composition according to any one of claims 1 to 4, wherein the resin includes at least one selected from the group consisting of β-caryophyllene, α-pinene, and β-pinene. The tire rubber composition according to any one of claims 1 to 5, wherein the resin includes at least one selected from the group consisting of styrene, a styrene derivative, β-caryophyllene, and α-pinene. The styrene derivative is at least selected from the group consisting of cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and a compound in which a hydrogen atom bonded to the benzene ring of styrene is substituted with a polar functional group. The tire rubber composition according to claim 6, which is one type. The styrene derivative is selected from the group consisting of cinnamic acid, cinnamic acid ester, cinnamyl alcohol, cinnamaldehyde, and compounds in which a hydrogen atom bonded to the 4-position carbon atom of styrene is substituted with a polar functional group The tire rubber composition according to claim 6, which is at least one kind. The rubber composition for tires according to any one of claims 1 to 8 containing silica. A pneumatic tire using the rubber composition according to claim 1.