JP2020105392A - Rubber composition for tire and pneumatic tire - Google Patents

Abstract

To improve processability in a rubber composition using a hydrogenated copolymer as a rubber component.SOLUTION: A rubber composition for tires according to an embodiment is a hydrogenated copolymer obtained by hydrogenating an aromatic vinyl-conjugate diene copolymer, in which a weight average molecular weight is 300,000 or larger and 0.1 to 20 pts.mass of an ether-ester compound having HLB expressed by a general formula (1) of 10 or smaller is contained relative to 100 pts.mass of the rubber component containing a hydrogenated copolymer having a hydrogenation rate of the conjugate diene of 80 mol% or larger. In the formula, R1 and R2 each is a hydrocarbon group having 1 to 30 carbons, R3 is an alkylene group having 2 to 4 carbons, n represents an average number of added moles of an oxyalkylene group, and 60 mass% or larger of (R3O)n is an oxyethylene group.SELECTED DRAWING: None

Description

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

For the purpose of improving fuel economy, breaking strength, wear resistance, etc., the rubber composition for a tire has a structural unit based on an aromatic vinyl compound and a structural unit based on a conjugated diene compound, and a conjugated diene part is included. It is known to blend a hydrogenated hydrogenated copolymer (Patent Documents 1 to 3).

However, when such a hydrogenated copolymer is used as a rubber component, the Mooney viscosity of the rubber composition becomes high and there is a problem in processability.

Patent Document 4 discloses that a polyoxyalkylene alkyl ether fatty acid ester (ether ester compound) is compounded in a rubber composition using a white filler, that is, silica as a filler. However, in this document, the fatty acid ester is blended in order to impart the antistatic performance of the rubber composition containing silica, and the workability and abrasion resistance are improved by blending the fatty acid ester. Is not listed. Further, the polyoxyalkylene alkyl ether fatty acid ester specifically used in Patent Document 4 has a high HLB, and there is no description of using a polyoxyalkylene alkyl ether fatty acid ester having an HLB of 10 or less.

JP, 2017-145341, A WO2014/133097 JP, 2018-95779, A JP, 10-330539, A

In view of the above points, an embodiment of the present invention aims to improve processability in a rubber composition using a hydrogenated copolymer as a rubber component.

The rubber composition for a tire according to the embodiment of the present invention is a hydrogenated copolymer in which an aromatic vinyl-conjugated diene copolymer is hydrogenated, has a weight average molecular weight of 300,000 or more, and has a conjugated diene part. To 100 parts by mass of a rubber component containing a hydrogenated copolymer having a hydrogenation rate of 80 mol% or more, an ether ester compound having an HLB of 10 or less represented by the following general formula (1) is 0.1 to 20. It includes parts by mass.

In the formula, R ¹ and R ² each independently represent a hydrocarbon group having 1 to 30 carbon atoms, R ³ represents an alkylene group having 2 to 4 carbon atoms, and n represents the average number of added moles of the oxyalkylene group. , (R ³ O) _{n comprises} 60% by mass or more of an oxyethylene group.

The pneumatic tire according to the embodiment of the present invention is manufactured using the rubber composition for a tire.

According to the embodiment of the present invention, the processability can be improved by using the hydrogenated copolymer in the rubber component and blending the ether ester compound.

The rubber composition according to the present embodiment is formed by blending a rubber component containing a hydrogenated copolymer and a specific ether ester compound.

[Hydrogenated copolymer]
The hydrogenated copolymer used as the rubber component is a hydrogenated copolymer in which an aromatic vinyl-conjugated diene copolymer is hydrogenated, has a weight average molecular weight (Mw) of 300,000 or more, and has a conjugated diene part. Is a hydrogenated copolymer having a hydrogenation rate of 80 mol% or more.

The aromatic vinyl constituting the aromatic vinyl-conjugated diene copolymer is not particularly limited, and examples thereof include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4 -Cyclohexylstyrene, 2,4,6-trimethylstyrene and the like can be mentioned. These may be used alone or in combination of two or more.

The conjugated diene constituting the aromatic vinyl-conjugated diene copolymer is not particularly limited, and for example, 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1. , 3-butadiene, 1,3-hexadiene and the like. These may be used alone or in combination of two or more.

The aromatic vinyl-conjugated diene copolymer is not particularly limited, but is preferably a copolymer of styrene and 1,3-butadiene (styrene-butadiene copolymer). Therefore, the hydrogenated copolymer is preferably a hydrogenated styrene-butadiene copolymer. The hydrogenated copolymer may be a random copolymer, a block copolymer or an alternating copolymer.

The hydrogenated copolymer can be synthesized, for example, by synthesizing an aromatic vinyl-conjugated diene copolymer and performing hydrogenation treatment. The method for synthesizing the aromatic vinyl-conjugated diene copolymer is not particularly limited, but a solution polymerization method, a gas phase polymerization method, a bulk polymerization method and the like can be mentioned, and the solution polymerization method is particularly preferable. Further, the polymerization system may be either a batch system or a continuous system. A commercially available aromatic vinyl-conjugated diene copolymer may be used.

The hydrogenation method is not particularly limited, and hydrogenation may be performed by a known method under known conditions. Usually, it is carried out in the presence of a hydrogenation catalyst under hydrogen pressure of 20 to 150° C. and 0.1 to 10 MPa. The hydrogenation rate can be arbitrarily selected by changing the amount of hydrogenation catalyst, hydrogen pressure during hydrogenation reaction, reaction time, and the like. As the hydrogenation catalyst, a compound containing any of metals of Groups 4 to 11 of the Periodic Table of Elements can be usually used. For example, compounds containing Ti, V, Co, Ni, Zr, Ru, Rh, Pd, Hf, Re and Pt atoms can be used as the hydrogenation catalyst. More specific hydrogenation catalysts include metallocene compounds such as Ti, Zr, Hf, Co, Ni, Pd, Pt, Ru, Rh, and Re; metal such as Pd, Ni, Pt, Rh, and Ru as carbon, A supported heterogeneous catalyst supported on a carrier such as silica, alumina, diatomaceous earth; a homogeneous Ziegler type catalyst in which an organic salt or acetylacetone salt of a metal element such as Ni or Co and a reducing agent such as organic aluminum are combined; Examples thereof include organic metal compounds or complexes such as Ru and Rh; fullerenes and carbon nanotubes in which hydrogen is occluded.

The hydrogenation rate of the hydrogenated copolymer is 80 mol% or more, preferably 80 to 95 mol%, more preferably 85 to 95 mol%, and further preferably 90 to 95 mol%. When the hydrogenation rate is 80 mol% or more, the effect of improving wear resistance due to homogenization of crosslinking is excellent. Here, the hydrogenation rate of the hydrogenated copolymer is the proportion of hydrogenated relative to the conjugated diene part (unit based on the conjugated diene compound) of the aromatic vinyl-conjugated diene copolymer, which is the value before hydrogenation. It is the molar ratio of the hydrogenated conjugated diene part when the entire conjugated diene part is 100 mol %. The hydrogenation rate of the hydrogenated copolymer is a value calculated from the spectrum reduction rate of the unsaturated bond portion of the spectrum obtained by measuring H ¹ -NMR.

The weight average molecular weight (Mw) of the hydrogenated copolymer measured by gel permeation chromatography (GPC) is not particularly limited as long as it is 300,000 or more, but 300,000 to 2,000,000 is preferable, and 300,000 to It is more preferably 1,000,000, and even more preferably 300,000 to 600,000. Here, the weight average molecular weight of the hydrogenated copolymer was measured using a differential refractive index detector (RI) as a detector, tetrahydrofuran (THF) as a solvent, a measurement temperature of 40° C. and a flow rate of 1.0 mL/min. The concentration was 1.0 g/L, the injection amount was 40 μL, and the values were calculated in terms of polystyrene using commercially available standard polystyrene.

[Rubber component]
The rubber component contains the above hydrogenated copolymer, and may be the hydrogenated copolymer alone or may contain other diene rubber together with the hydrogenated copolymer.

The content ratio of the hydrogenated copolymer in the rubber component is preferably 70 to 100% by mass. That is, it is preferable that 70 to 100 parts by mass of the hydrogenated copolymer is contained in 100 parts by mass of the rubber component. The content ratio of the hydrogenated copolymer in the rubber component is more preferably 80 to 100% by mass.

The other diene rubber that may be used in combination with the hydrogenated copolymer may be a solid rubber that is solid at room temperature (23°C) or a liquid rubber that is liquid at room temperature (23°C). It may be.

Examples of the solid rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene. —Isoprene-butadiene copolymer rubber and the like. These solid rubbers may be used alone or in a blend of two or more.

Examples of the liquid rubber include liquid isoprene rubber, liquid butadiene rubber, liquid styrene butadiene rubber, liquid isoprene butadiene rubber, liquid isoprene styrene rubber, liquid isoprene butadiene styrene rubber, liquid isobutylene, liquid ethylene propylene diene rubber (EPDM). .. These liquid rubbers may be modified by carboxylation or methacrylate conversion. These liquid rubbers may be used alone or in a blend of two or more.

A commercially available product may be used as the liquid rubber. For example, as the liquid isoprene rubber, LIR-30, LIR-50, LIR-310, LIR-390, LIR-410 manufactured by Kuraray Co., Ltd. may be used. UC-203, UC-102, LIR-290, LIR-700, etc. are mentioned, as liquid butadiene rubber, LBR-307, LBR-305, LBR-352 manufactured by the same company, and liquid styrene butadiene rubber manufactured by the same company. L-SBR-820, L-SBR-841 and the like.

The weight average molecular weight of the liquid rubber is not particularly limited, but is preferably 1000 to 100,000, and may be 2000 to 50,000.

The content of the liquid rubber (total amount when two or more kinds are used) is preferably 30 parts by mass or less, more preferably 1 to 30 parts by mass, and 3 to 20 parts by mass in 100 parts by mass of the rubber component. More preferably, it is a part.

[Ether ester compound]
The rubber composition according to the present embodiment includes the above hydrogenated copolymer as a rubber component, an ether ester compound having an HLB of 10 or less represented by the following general formula (1) (preferably polyoxyalkylene alkyl ether fatty acid). Ester) is blended. Since the hydrogenated copolymer has reduced polarity due to hydrogenation, a surfactant having a low HLB is preferably used. Further, since the ether ester compound exhibits a plasticizing effect in the rubber composition, it is considered that the viscosity at the time of kneading the rubber composition is reduced. Therefore, by using the ether ester compound, it is possible to improve workability and wear resistance.

In formula (1), R ¹ and R ² each independently represent a hydrocarbon group having 1 to 30 carbon atoms, R ³ represents an alkylene group having 2 to 4 carbon atoms, and n represents an average addition mole of an oxyalkylene group. Representing a number, 60% by mass or more of (R ³ O) _n is composed of an oxyethylene group.

As described above, R ¹ and R ² each independently represent a hydrocarbon group having 1 to 30 carbon atoms, and the hydrocarbon group preferably has 5 to 25 carbon atoms, and more preferably 8 to 22 carbon atoms. And may be 10 to 20. Further, the hydrocarbon group is preferably a linear or branched saturated or unsaturated aliphatic hydrocarbon group, for example, an alkyl group or an alkenyl group. In one embodiment, R ¹ is preferably an alkyl group or alkenyl group having 1 to 25 carbon atoms, and more preferably an alkyl group or alkenyl group having 8 to 20 carbon atoms. Further, R ² is preferably an alkyl group or an alkenyl group having 8 to 25 carbon atoms, and more preferably an alkyl group or alkenyl group having 12 to 20 carbon atoms.

As described above, R ³ represents an alkylene group having 2 to 4 carbon atoms, and n represents the average number of added moles of the oxyalkylene group. The alkylene group for R ³ may be linear or branched. Examples of the oxyalkylene group represented by R ³ O include an oxyethylene group, an oxypropylene group and an oxybutylene group. (R ³ O) _n in formula (1) is a polyoxyalkylene chain obtained by addition-polymerizing an alkylene oxide having 2 to 4 carbon atoms (for example, ethylene oxide, propylene oxide, butylene oxide, etc.). The polymerization form of alkylene oxide or the like is not particularly limited, and may be a homopolymer, a random copolymer, or a block copolymer.

(R ³ O) _n in the formula (1) is preferably composed mainly of an oxyethylene group, and 60% by mass or more of (R ³ O) _n is composed of an oxyethylene group. That is, the polyoxyalkylene chain represented by (R ³ O) _n contains 60% by mass or more, preferably 80% by mass or more of oxyethylene groups (total oxyalkylene constituting the polyoxyalkylene chain). The group is 100% by mass). More preferably, the polyoxyalkylene chain contains 100% by mass of oxyethylene group, that is, consists of only oxyethylene group as represented by the following general formula (2).

^R 1, ^{R 2} and n in formula (2) is the same as ^R 1, ^{R 2} and n in formula (1).

N, which represents the average number of moles of addition of the oxyalkylene group, is a number that is set so that the HLB of the ether ester compound is 10 or less, and varies depending on the types of R ¹ and R ² , but may be, for example, 1 to 20. , 2-15, or 3-10.

The HLB (hydrophilic/lipophilic balance) of the ether ester compound is 10 or less as described above, more preferably 3 to 10, and further preferably 4 to 8. Here, HLB is a value calculated by the following Griffin's formula, and the larger the value, the larger the proportion of the hydrophilic portion in the whole molecule and the higher the hydrophilicity.
HLB=20×(molecular weight of hydrophilic part)/(total molecular weight)
The molecular weight of the hydrophilic portion in the formula is the molecular weight of the polyoxyalkylene chain represented by (R ³ O) _n .

The content of the ether ester compound is preferably 0.1 to 20 parts by mass, more preferably 1 to 20 parts by mass, and further preferably 2 to 15 parts by mass with respect to 100 parts by mass of the rubber component. It may be 3 to 10 parts by mass. The greater the amount of the ether ester compound compounded, the higher the effect of improving the workability and wear resistance, but even if added in an amount of more than 20 parts by mass, the further improvement of the effect is small. It is preferably less than or equal to parts by mass.

[Reinforcing filler]
The rubber composition according to the present embodiment may contain silica as a reinforcing filler. By adding silica, the effect of improving wet grip performance can be enhanced. The silica is not particularly limited, and wet silica such as wet precipitation silica and wet gel silica may be used.

The content of silica is not particularly limited, and may be 10 to 150 parts by mass, 20 to 100 parts by mass, or 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

As the reinforcing filler, silica may be used alone, or silica and carbon black may be used in combination. The carbon black is not particularly limited, and various known types such as SAF class (N100 series), ISAF class (N200 series), HAF class (N300 series), FEF class (N500 series) (both are ASTM grades). May be used alone or in combination of two or more. The content of carbon black is not particularly limited, and may be 1 to 80 parts by mass, 1 to 50 parts by mass, or 2 to 15 parts by mass with respect to 100 parts by mass of the rubber component. In the present embodiment, it is preferable to use silica as the main reinforcing filler, for example, 50% by mass or more of the reinforcing filler is preferably silica, and more preferably 70% by mass or more of the reinforcing filler is silica. Is.

When silica is used as the reinforcing filler, it is preferable to include a silane coupling agent. Examples of the silane coupling agent include sulfide silane and mercapto silane. The content of the silane coupling agent is not particularly limited, and may be, for example, 2 to 20 mass% with respect to the silica content.

[Other compounding agents]
In the rubber composition according to the present embodiment, in addition to the above components, an oil, a resin, stearic acid, zinc oxide, an antioxidant, a wax, a processing aid, a vulcanizing agent, a vulcanization accelerator, etc., a rubber for tires. Various additives generally used in the composition can be blended.

As the vulcanization accelerator, for example, sulfenamide-based vulcanization accelerator, thiuram-based vulcanization accelerator, thiazole-based vulcanization accelerator, thiourea-based vulcanization accelerator, guanidine-based vulcanization accelerator, dithiocarbamate-based vulcanization accelerator Various vulcanization accelerators such as vulcanization accelerators can be used. Among these, the rubber composition according to the present embodiment preferably contains a guanidine vulcanization accelerator and a dithiocarbamate vulcanization accelerator. A sulfenamide-based vulcanization accelerator may be contained together with the guanidine-based vulcanization accelerator and the dithiocarbamate-based vulcanization accelerator.

Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine (D) and 1,3-di-o-tolylguanidine (DT).

Examples of the dithiocarbamate vulcanization accelerator include zinc dibenzyldithiocarbamate (ZnBzDTC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc di-n-butyldithiocarbamate (ZnBDC), Zinc N-pentamethylenedithiocarbamate (ZnPDC), zinc ethylphenyldithiocarbamate (ZnEPDC), sodium dimethyldithiocarbamate (NaMDC), sodium diethyldithiocarbamate (NaEDC), sodium di-n-butyldithiocarbamate (NaBDC), diethyldithiocarbamine Examples thereof include acid tellurium (TeEDC), copper dimethyldithiocarbamate (CuMDC), and iron dimethyldithiocarbamate (FeMDC).

Examples of the sulfenamide vulcanization accelerator include N-cyclohexyl-2-benzothiazolyl sulfenamide (CZ), N-tert-butyl-2-benzothiazolyl sulfenamide (NS), N-oxy. Examples thereof include diethylene-2-benzothiazolyl sulfenamide (OBS) and N,N-diisopropyl-2-benzothiazole sulfenamide (DZ).

The mixing ratio of the dithiocarbamate vulcanization accelerator and the guanidine vulcanization accelerator (guanidine vulcanization accelerator/dithiocarbamate vulcanization accelerator) is 0.5 to 3.0 by mass ratio. It is preferable.

The content of the guanidine-based vulcanization accelerator is not particularly limited, and may be 0.1 to 3 parts by mass or 0.2 to 2 parts by mass with respect to 100 parts by mass of the rubber component. The content of the dithiocarbamate vulcanization accelerator is not particularly limited, and may be 0.1 to 3 parts by mass or 0.2 to 2 parts by mass with respect to 100 parts by mass of the rubber component. The content of the sulfenamide vulcanization accelerator is not particularly limited, and may be 0.1 to 3 parts by mass or 0.2 to 2 parts by mass with respect to 100 parts by mass of the rubber component. The total content of vulcanization accelerators is not particularly limited, and may be 0.1 to 7 parts by mass, or 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

Sulfur is preferably used as the vulcanizing agent. The compounding amount of the vulcanizing agent is not particularly limited, and may be, for example, 0.1 to 10 parts by mass or 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

[Preparation of rubber composition, etc.]
The rubber composition according to the present embodiment can be prepared by kneading according to a conventional method using a mixer such as a Banbury mixer, a kneader, or a roll that is commonly used. That is, for example, in the first mixing step (non-pro kneading step), additives other than the vulcanizing agent and the vulcanization accelerator are added and mixed with the rubber component, and then the resulting mixture is subjected to the final mixing step (pro-kneading step). In the kneading step), a vulcanizing agent and a vulcanization accelerator can be added and mixed to prepare an unvulcanized rubber composition.

The rubber composition according to the present embodiment can be used, for example, for tires of various applications such as passenger cars, heavy loads of trucks and buses, and is applied to each part of the tire such as the tread portion and sidewall portion of a pneumatic tire. be able to. It is preferably used for a tread of a pneumatic tire, that is, a rubber composition for a tire tread.

The pneumatic tire according to one embodiment uses the above rubber composition to produce a tire member such as a tread rubber using a rubber extruder or the like, and produces an unvulcanized tire (green tire) in combination with another tire member. After that, it can be manufactured by vulcanization molding at 140 to 180° C., for example. For example, tread rubbers for pneumatic tires include those having a two-layer structure of a cap rubber and a base rubber, and those having a single-layer structure in which both are integrated, but they are preferably used as the rubber constituting the ground contact surface. That is, when the tread rubber has a single-layer structure, the tread rubber is preferably composed of the rubber composition, and when the tread rubber has a two-layer structure, the cap rubber is preferably composed of the rubber composition.

Examples will be shown below, but the present invention is not limited to these examples.

The measuring method for the hydrogenated copolymer is as follows.

[Measurement of weight average molecular weight (Mw)]
The Mw of the hydrogenated copolymer was determined by gel permeation chromatography (GPC) and calculated as Mw in terms of polystyrene. Specifically, "LC-10A" manufactured by Shimadzu Corporation as a measuring device, "PLgel-MIXED-C" manufactured by Polymer Laboratories as a column, a differential refractive index detector (RI) as a detector, and THF as a solvent were used. The measurement temperature was 40° C., the flow rate was 1.0 mL/min, the concentration was 1.0 g/L, and the injection amount was 40 μL.

[Measurement of hydrogenation rate]
The hydrogenation rate of the conjugated diene part of the hydrogenated copolymer was calculated from the spectral reduction rate of the unsaturated bond part of the spectrum obtained by measuring H ¹ -NMR.

[Measurement of bound styrene content]
The amount of bound styrene of the hydrogenated copolymer was determined from the spectral intensity ratio of the proton based on the styrene unit and the proton based on the butadiene unit (including the hydrogenated portion) using H ¹ -NMR.

[Synthesis Example 1: Synthesis of hydrogenated copolymer 1]
2.5 liters of cyclohexane, 50 g of tetrahydrofuran (THF), 0.12 g of n-butyllithium, 100 g of styrene, 400 g of 1,3-butadiene were placed in a nitrogen-substituted heat-resistant reaction vessel, and polymerization was carried out at a reaction temperature of 50°C. I went. After the polymerization was completed, 1.7 g of N,N-bis(trimethylsilyl)aminopropylmethyldiethoxylane was added and reacted for 1 hour, and then hydrogen gas was supplied at a pressure of 0.4 MPa-gauge and stirred for 20 minutes. did. Then, the hydrogen gas supply pressure was set to 0.7 MPa-gauge, the reaction temperature was set to 90° C., the reaction was carried out using a catalyst mainly composed of titanocene dichloride until the target hydrogenation rate was reached, and the solvent was removed, whereby hydrogenation was carried out. Copolymer 1 was obtained. The hydrogenated copolymer 1 thus obtained was a hydrogenated styrene-butadiene rubber, had an Mw of 350,000, a bound styrene content of 20 mass %, and a hydrogenation rate of the butadiene part of 90 mol %.

[Synthesis Example 2: Synthesis of hydrogenated copolymer 2]
A hydrogenated copolymer 2 was obtained in the same manner as in Synthesis Example 1 except that the reaction time for hydrogenation was changed and the hydrogenation rate was changed. The hydrogenated copolymer 2 thus obtained was a hydrogenated styrene-butadiene rubber, had an Mw of 350,000, a bound styrene content of 20 mass% and a hydrogenation rate of 80 mol% in the butadiene part.

[Synthesis Example 3: Synthesis of ether ester compound 1]
To 47 g (0.25 mol) of lauryl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of potassium hydroxide catalyst was added, and ethylene oxide (manufactured by Tokyo Chemical Industry Co., Ltd.) 330 g with stirring at 110 to 120° C. (7.5 mol) was injected under pressure to carry out addition reaction. The reaction was transferred to a flask and the potassium hydroxide catalyst was neutralized with phosphoric acid. The phosphate was filtered off from the neutralized product to obtain 336 g (yield: 76% by mass) of a 30 mol lauryl alcohol ethylene oxide adduct. 200 g (0.11 mol) of 30 mol of the obtained lauryl alcohol ethylene oxide adduct, 34 g (0.12 mol) of oleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.7 g of dibutyltin oxide as a catalyst were measured. Then, a dehydration esterification reaction was carried out at 225° C. with stirring under nitrogen blowing to obtain an ether ester compound 1. The obtained compound is an ether ester compound with R ¹ =C ₁₂ H ₂₅ , R ² =C ₁₇ H ₃₃ and n=30 in the formula (2), and HLB=15.

[Synthesis Example 4: Synthesis of ether ester compound 2]
To 30 g (0.15 mol) of tridecyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of potassium hydroxide catalyst was added, and ethylene oxide (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred at 110 to 120°C. 46 g (1.05 mol) was injected under pressure to carry out addition reaction. The reaction was transferred to a flask and the potassium hydroxide catalyst was neutralized with phosphoric acid. The phosphate was filtered off from the neutralized product to obtain 64 g (yield: 85% by mass) of a 7 mol adduct of tridecyl alcohol ethylene oxide. 60 g (0.12 mol) of the obtained 7 mol adduct of tridecyl alcohol ethylene oxide, 37 g (0.13 mol) of stearic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.7 g of dibutyltin oxide as a catalyst were weighed. Then, a dehydration esterification reaction was carried out at 225° C. with stirring under nitrogen blowing to obtain an ether ester compound 2. The obtained compound is an ether ester compound with R ¹ =C ₁₃ H ₂₇ , R ² =C ₁₇ H ₃₅ , n=7 in the formula (2), and HLB=8.

[Synthesis Example 5: Synthesis of ether ester compound 3]
To 47 g (0.25 mol) of lauryl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of potassium hydroxide catalyst was added, and while stirring at 110 to 120° C., 33 g of ethylene oxide (manufactured by Tokyo Chemical Industry Co., Ltd.). (1.5 mol) was injected under pressure to carry out addition reaction. The reaction was transferred to a flask and the potassium hydroxide catalyst was neutralized with phosphoric acid. The phosphate was filtered off from the neutralized product to obtain 150 g of lauryl alcohol ethylene oxide 6 mol adduct (yield 84% by mass). 135 g (0.19 mol) of the obtained lauryl alcohol ethylene oxide 6 mol adduct, 56 g (0.2 mol) of oleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.7 g of dibutyltin oxide as a catalyst were measured. Then, a dehydration esterification reaction was carried out at 225° C. with stirring under nitrogen blowing to obtain an ether ester compound 3. The obtained compound is an ether ester compound with R ¹ =C ₁₂ H ₂₅ , R ² =C ₁₇ H ₃₃ , n=6 in the formula (2), and HLB=7.

[Synthesis Example 6: Synthesis of ether ester compound 4]
To 47 g (0.25 mol) of lauryl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of potassium hydroxide catalyst was added, and while stirring at 110 to 120° C., 33 g of ethylene oxide (manufactured by Tokyo Chemical Industry Co., Ltd.). (0.75 mol) was injected under pressure to carry out addition reaction. The reaction was transferred to a flask and the potassium hydroxide catalyst was neutralized with phosphoric acid. The phosphate was filtered off from the neutralized product to obtain 72 g of lauryl alcohol ethylene oxide 3 mol adduct (yield 90% by mass). 60 g (0.19 mol) of the obtained lauryl alcohol ethylene oxide 3 mol adduct, 56 g (0.2 mol) of oleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.7 g of dibutyltin oxide as a catalyst were weighed. Then, a dehydration esterification reaction was carried out at 225° C. with stirring under nitrogen blowing to obtain an ether ester compound 4. The obtained compound is an ether ester compound with R ¹ =C ₁₂ H ₂₅ , R ² =C ₁₇ H ₃₃ and n=3 in the formula (2), and HLB=5.

[Synthesis Example 7: Synthesis of ether ester compound 5]
To 54 g (0.2 mol) of oleyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.1 g of a potassium hydroxide catalyst was added, and 26 g of ethylene oxide (manufactured by Tokyo Chemical Industry Co., Ltd.) while stirring at 110 to 120° C. (0.6 mol) was injected under pressure to carry out addition reaction. The reaction was transferred to a flask and the potassium hydroxide catalyst was neutralized with phosphoric acid. The phosphate was filtered off from the neutralized product to obtain 69 g (yield 90% by mass) of a 3 mol adduct of oleyl alcohol ethylene oxide. 58 g (0.15 mol) of the obtained oleyl alcohol ethylene oxide 3 mol adduct, 47 g (0.165 mol) of stearic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.7 g of dibutyltin oxide as a catalyst were measured. Then, a dehydration esterification reaction was carried out at 225° C. with stirring under nitrogen blowing to obtain an ether ester compound 5. The obtained compound is an ether ester compound with R ¹ =C ₁₈ H ₃₅ , R ² =C ₁₇ H ₃₅ , n=3 in the formula (2), and HLB=4.

[Preparation and evaluation of rubber composition]
Using a Banbury mixer, according to the formulation (parts by mass) shown in Table 1 below, first, in the first mixing stage, the components excluding sulfur and the vulcanization accelerator are added and kneaded (exhaust temperature=160° C.), then At the final mixing stage, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded (discharging temperature=90° C.) to prepare a rubber composition.

Details of each component in Table 1 are as follows.
Hydrogenated SBR1: Hydrogenated copolymer 1 prepared according to Synthesis Example 1
Hydrogenated SBR2: Hydrogenated copolymer 2 produced according to Synthesis Example 2
・Silica: "Ultrasil VN3" manufactured by Evonik Industries
・Carbon black: "Seast 3" manufactured by Tokai Carbon Co., Ltd.
・Silane coupling agent: "Si69" manufactured by Evonik Industries
・Oil: "Process NC140" manufactured by JXTG Energy Co., Ltd.
・Anti-aging agent: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Co., Ltd.
・Wax: "OZOACE0355" manufactured by Nippon Seiro Co., Ltd.
・Stearic acid: "Lunack S-20" manufactured by Kao Corporation
・Zinc oxide: "Zinc Hua No. 3" manufactured by Mitsui Mining & Smelting Co., Ltd.
Compound 1 (HLB15): ether ester compound 1 prepared according to Synthesis Example 3
Compound 2 (HLB8): ether ester compound 2 prepared according to Synthesis Example 4
Compound 3 (HLB7): ether ester compound 3 prepared according to Synthesis Example 5
Compound 4 (HLB5): ether ester compound 4 prepared according to Synthesis Example 6
Compound 5 (HLB4): ether ester compound 5 prepared according to Synthesis Example 7
・Sulfur: "Powdered sulfur" manufactured by Tsurumi Chemical Industry Co., Ltd.
・Vulcanization accelerator 1: "Succinol CZ" manufactured by Sumitomo Chemical Co., Ltd., sulfenamide-based vulcanization accelerator 2: "Noxera-D" manufactured by Ouchi Shinko Chemical Co., Ltd., guanidine-based vulcanization accelerated Agent 3: "SANCELLER ZBE" manufactured by Sanshin Chemical Industry Co., Ltd., dithiocarbamate type

With respect to each of the obtained rubber compositions, workability was evaluated, and test pieces were prepared by vulcanizing at 160° C. for 30 minutes to evaluate wear resistance. The evaluation method is as follows.
-Workability: Using a rotorless Mooney measuring machine manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K6300, the unvulcanized rubber was preheated at 100°C for 1 minute, and the torque value after 4 minutes was measured in Mooney units. The reciprocal of the measured value was expressed as an index with the value of Comparative Example 1 as 100. The larger the index, the lower the Mooney viscosity and the better the processability.

-Abrasion resistance: In accordance with JIS K6264, a Lambourn abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd. was used to measure the abrasion loss under the conditions of a load of 29 N, a slip ratio of 20%, and a temperature of 23°C, and the reciprocal of the measured value. Was displayed as an index with the value of Comparative Example 1 as 100. The larger the index, the smaller the loss on wear and the better the wear resistance.

The results are shown in Table 1. In Comparative Example 2 in which an ether ester compound having a high HLB was added, in contrast to Comparative Example 1 in which a hydrogenated copolymer was used as a rubber component, the wear resistance was deteriorated and the workability improving effect was small. On the other hand, in Examples 1 to 7 in which the ether ester compound having a low HLB was added, the workability could be improved and the wear resistance could be improved.

Claims (2)

A hydrogenated copolymer obtained by hydrogenating an aromatic vinyl-conjugated diene copolymer, the hydrogenated copolymer having a weight average molecular weight of 300,000 or more and a hydrogenation rate of the conjugated diene portion of 80 mol% or more. A rubber composition for a tire, which contains 0.1 to 20 parts by mass of an ether ester compound having an HLB represented by the following general formula (1) of 10 or less based on 100 parts by mass of a rubber component containing a polymer.

In the formula, R ¹ and R ² each independently represent a hydrocarbon group having 1 to 30 carbon atoms, R ³ represents an alkylene group having 2 to 4 carbon atoms, and n represents the average number of added moles of the oxyalkylene group. , (R ³ O) _{n comprises} 60% by mass or more of an oxyethylene group. A pneumatic tire produced using the rubber composition for a tire according to claim 1.