JP2024027632A - rubber composition - Google Patents

Abstract

The present invention provides a rubber composition that exhibits abrasion resistance, dry performance, wet performance, and on-snow performance. [Solution] A rubber component containing 100 parts by mass of SBR and optionally other diene rubber, 20 to 150 parts by mass of a white filler, and a total of 20 to 100 parts by mass of a thermoplastic resin and a plasticizer, based on the above total. The thermoplastic resin is 65% by mass or more, the difference between the Tg of the diene rubber with the highest content and the Tg of the thermoplastic resin is 100°C or more, and the half value width of the temperature dependence curve of tan δ of the rubber composition is σbf, and the half value width of tan δ is Let tan δ at a temperature 90° C. higher than the peak temperature be tan δbf, the half width of tan δ of the rubber composition after immersing and drying the rubber composition in toluene be σaf, and the tan δ at a temperature 90° C. higher than the peak temperature of tan δ be tan δaf. When, |σbf−σaf|≧4 and |tanδbf−tanδaf|≦0.02 are satisfied. [Selection diagram] None

Description

The present invention relates to a rubber composition that achieves both abrasion resistance, low rolling resistance, wet performance, and on-snow performance.

Winter tires are required to have high levels of wear resistance, low rolling resistance, wet performance, and on-snow performance. Patent Document 1 proposes blending an aromatic modified terpene resin and an oil into a rubber composition as a rubber composition for a tire tread that improves abrasion resistance, low rolling resistance, and wet performance.

However, in recent years, winter tires have been required to have a balance of wear resistance, low rolling resistance, and wet performance at a higher level than that described in Patent Document 1, and to have excellent on-snow performance. is required.

Japanese Patent Application Publication No. 2013-166864

An object of the present invention is to provide a rubber composition that achieves higher levels of abrasion resistance, low rolling resistance, wet performance, and on-snow performance than conventional levels.

The rubber composition of the present invention which achieves the above object is composed of 100 parts by mass of a rubber component containing styrene-butadiene rubber and optionally other diene rubber, 20 to 150 parts by mass of a white filler, a thermoplastic resin and optionally a plasticizer. A rubber composition containing a total of 20 parts by mass or more and 100 parts by mass or less of an agent, wherein the proportion of the thermoplastic resin with respect to the total of the thermoplastic resin and the plasticizer is 65% by mass or more, and the rubber composition contains in the rubber component. The difference Tgr-Tgp between the glass transition temperature Tgp (°C) of the styrene-butadiene rubber or other diene rubber having the largest amount and the glass transition temperature Tgr (°C) of the thermoplastic resin is 100°C or more, and the rubber composition The half-width in the temperature dependence curve of tan δ of the product is σbf (°C), and the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ is maximum is tan δbf, and the rubber composition is immersed in toluene and dried. When the half-width in the temperature dependence curve of tan δ of the rubber composition is σaf (°C), and the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ is maximum is tan δaf, the following relational expression (1) and It is characterized by satisfying (2).
|σbf−σaf|≧4 (1)
|tanδbf−tanδaf|≦0.02 (2)

The rubber composition of the present invention contains styrene-butadiene rubber, another diene rubber, and a white filler, and a thermoplastic resin and a plasticizer in a specific blending ratio. If the difference between the glass transition temperatures of the resins is 100°C or more, the half-value width σ of the temperature dependence curve of tan δ, and the tan δ Since the tan δ at a temperature 90°C higher than the maximum peak temperature has been made to satisfy a specific relationship, it has achieved a higher level of wear resistance, low rolling resistance, wet performance, and on-snow performance than conventional levels. Can be done.

The other diene rubber is selected from isoprene rubber and butadiene rubber, and out of 100% by mass of the rubber component, the isoprene rubber is 0 to 15% by mass, the butadiene rubber is 5 to 45% by mass, and the styrene butadiene rubber is 0 to 15% by mass, and the butadiene rubber is 5 to 45% by mass. Preferably, the rubber content is 40 to 95% by weight. Further, it is preferable that at least one end of the styrene-butadiene rubber is modified with a functional group.

The thermoplastic resin has a glass transition temperature Tgr of 40° C. to 120° C., and the thermoplastic resin is a resin consisting of at least one selected from terpene, modified terpene, rosin, rosin ester, C5 component, and C9 component. , and resins in which at least some of the double bonds of these resins are hydrogenated.

The rubber composition of the present invention contains styrene-butadiene rubber and optionally another diene rubber as a rubber component. The styrene-butadiene rubber may contain one type alone or a blend of two or more types. By including styrene-butadiene rubber, the tensile strength at break is increased and wear resistance is increased, and by improving the dispersibility of silica, tan δ at 0°C is increased and wet performance is improved. can.

The styrene-butadiene rubber has a glass transition temperature (hereinafter sometimes referred to as "Tg") of preferably -55°C or lower, more preferably -80°C to -58°C, and even more preferably -75°C to -60°C. It is good if it is ℃. It is preferable to set the Tg of the styrene-butadiene rubber to −55° C. or lower because it can improve wear resistance. The Tg of styrene-butadiene rubber can be measured as the temperature at the midpoint of the transition range from a thermogram obtained by differential scanning calorimetry (DSC) at a heating rate of 20° C./min. Furthermore, when the styrene-butadiene rubber is an oil-extended product, the Tg is defined as the Tg in a state that does not contain an oil-extending component (oil).

The styrene butadiene rubber has a styrene content of, but not limited to, preferably 5 to 45% by mass, more preferably 8 to 42% by mass. By controlling the styrene content within this range, wear resistance is improved, which is preferable.

Furthermore, the vinyl content of the styrene-butadiene rubber is not particularly limited, but is preferably 5 to 60%, more preferably 10 to 55%. By controlling the vinyl content within this range, excellent dry grip performance can be achieved, which is preferable. The styrene content and vinyl content in styrene-butadiene rubber can be measured by ¹ H-NMR.

The styrene-butadiene rubber preferably has at least one end modified with a functional group, which can improve the dispersibility of silica and lower the rolling resistance of the tire. Examples of functional groups include epoxy groups, carboxy groups, amino groups, hydroxy groups, alkoxy groups, silyl groups, alkoxysilyl groups, amide groups, oxysilyl groups, silanol groups, isocyanate groups, isothiocyanate groups, carbonyl groups, aldehyde groups, etc. Among them, those having a polyorganosiloxane structure or an aminosilane structure are preferably mentioned. By having a functional group having a polyorganosiloxane structure or an aminosilane structure, it is possible to improve the dispersibility of silica and to improve abrasion resistance, low rolling resistance, wet performance, and performance on snow.

The content of styrene-butadiene rubber is preferably 40% by mass or more, more preferably 40 to 100% by mass, even more preferably 40 to 95% by mass, particularly preferably 60 to 90% by mass based on 100% by mass of the rubber component. Good. The content of styrene-butadiene rubber is the content of the styrene-butadiene rubber when one type is contained alone, and the total amount of those styrene-butadiene rubbers when it is contained as a blend of two or more types. By containing 55% by mass or more of styrene-butadiene rubber, it is possible to improve the dispersibility of silica and improve abrasion resistance, wet performance, and on-snow performance.

The rubber composition can optionally contain diene rubbers other than styrene-butadiene rubber. Examples of other diene rubbers include natural rubber, isoprene rubber, butadiene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile-butadiene rubber, and modified rubbers obtained by adding functional groups to these rubbers. These other diene rubbers can be used alone or in any blend.

The rubber composition is preferably blended with isoprene-based rubber such as natural rubber or isoprene rubber, as this improves wear resistance. The isoprene rubber is preferably used in an amount of 0 to 15% by weight, more preferably 5 to 10% by weight based on 100% by weight of the rubber component. As the isoprene rubber, it is preferable to use natural rubber, which is commonly used in rubber compositions.

The rubber composition is preferably blended with butadiene rubber, as this improves abrasion resistance and on-snow performance. The butadiene rubber is preferably used in an amount of 5 to 45% by weight, more preferably 10 to 30% by weight based on 100% by weight of the rubber component. As the butadiene rubber, those commonly used in rubber compositions may be used.

The wet performance of the rubber composition can be improved by incorporating a white filler into the rubber component. Examples of the white filler include silica, calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide, and calcium sulfate. These may be used alone or in combination of two or more. Among these, silica is preferred, as it can provide better wet performance and low heat build-up. The white filler is preferably blended in an amount of 20 to 150 parts by weight, preferably 40 to 150 parts by weight, more preferably 60 to 140 parts by weight, to 100 parts by weight of the rubber component. By blending 20 parts by mass or more of the white filler, wet performance and abrasion resistance can be improved. Moreover, by blending 150 parts by mass or less, excellent wear resistance and low rolling resistance can be achieved.

As the silica, those commonly used in rubber compositions may be used, such as wet process silica, dry process silica, carbon-silica (dual phase filler) in which silica is supported on the surface of carbon black, silane coupling. It is possible to use silica that has been surface-treated with a compound that is reactive or compatible with both silica and rubber, such as an agent or polysiloxane. Among these, wet process silica containing hydrous silicic acid as a main component is preferred.

Further, it is preferable to mix a silane coupling agent with silica because it improves the dispersibility of silica and further improves wet performance and low heat build-up. The type of silane coupling agent is not particularly limited, but sulfur-containing silane coupling agents are preferred, such as bis-(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, etc. Sulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3 -Mercaptopropyltrimethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyldimethylmethoxysilane, 2-mercaptoethyltriethoxysilane, 3-mercaptopropyltriethoxysilane, and VP Si363 manufactured by Evonik, etc., JP Si363 manufactured by Evonik, etc. Mercaptosilane compounds etc. exemplified in Publication No. 2006-249069, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3 -Trimethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl- N,N-dimethylthiocarbamoyltetrasulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, 3 -Octanoylthiopropyltriethoxysilane, 3-propionylthiopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane Sidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-( Examples include β-aminoethyl)-γ-aminopropylmethyldimethoxysilane.

The silane coupling agent is preferably blended in an amount of 3 to 20% by mass, more preferably 5 to 15% by mass, based on the mass of silica. When the amount of the silane coupling agent is 3% by mass or more based on the mass of silica, it is advantageous for improving the dispersibility of silica. Moreover, when the silane coupling agent is contained in an amount of 20% by mass or less, gelation of the rubber component can be suppressed and a desired effect can be obtained.

By blending fillers other than the white filler with the rubber composition, the strength of the rubber composition can be increased and tire durability can be ensured. Examples of other fillers include inorganic fillers such as carbon black, mica, aluminum oxide, and barium sulfate, and organic fillers such as cellulose, lecithin, lignin, and dendrimers.

Among these, by blending carbon black, the strength of the rubber composition can be made excellent. As the carbon black, carbon blacks such as furnace black, acetylene black, thermal black, channel black, and graphite may be blended. Among these, furnace black is preferred, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS, FEF, and the like. These carbon blacks can be used alone or in combination of two or more. Furthermore, surface-treated carbon blacks obtained by chemically modifying these carbon blacks with various acid compounds can also be used.

The temperature dependence of the dynamic viscoelasticity of the rubber composition can be adjusted by blending a specific thermoplastic resin with an optional plasticizer. The total amount of the thermoplastic resin and plasticizer is 20 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the rubber component. That is, 20 parts by mass or more and 100 parts by mass or less of a thermoplastic resin may be blended without containing a plasticizer, or a thermoplastic resin and a plasticizer containing a plasticizer may be blended in a total of 20 parts by mass or more and 100 parts by mass or less. You may. By blending the thermoplastic resin and plasticizer within such ranges, it is possible to achieve both abrasion resistance, low rolling resistance, wet performance, and on-snow performance. The total amount of the thermoplastic resin and plasticizer is preferably 25 parts by mass or more and 80 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less.

In the rubber composition, the ratio of the thermoplastic resin to the total of the thermoplastic resin and the plasticizer is 65% by mass or more. By making the thermoplastic resin content 65% by mass or more, wear resistance can be improved. The ratio of the thermoplastic resin to the total of the thermoplastic resin and the plasticizer is preferably 70% by mass or more and 100% by mass or less, more preferably 75% by mass or more and 100% by mass or less.

A thermoplastic resin is a resin that is usually blended into a rubber composition, and has the effect of imparting tackiness to the rubber composition. As a thermoplastic resin, a group consisting of a resin consisting of at least one selected from terpene, modified terpene, rosin, rosin ester, C5 component, and C9 component, and a resin in which at least a portion of the double bonds of these resins are hydrogenated. It is preferable that it is at least one selected from the following. For example, natural resins such as terpene resins, modified terpene resins, rosin resins, and rosin ester resins, petroleum resins consisting of C5 and C9 components, synthetic resins such as coal resins, phenolic resins, and xylene resins. can be mentioned. Further, resins in which at least a portion of the double bonds of these resins are hydrogenated may also be used.

Examples of the terpene resin include α-pinene resin, β-pinene resin, limonene resin, hydrogenated limonene resin, dipentene resin, terpene styrene resin, aromatic modified terpene resin, and hydrogenated terpene resin. Examples of rosin-based resins include gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, modified rosin such as maleated rosin and fumarized rosin, glycerin esters of these rosins, pentaerythritol esters, Examples include ester derivatives such as methyl ester and triethylene glycol ester, and rosin-modified phenol resins.

Petroleum-based resins include aromatic hydrocarbon resins and saturated or unsaturated aliphatic hydrocarbon resins, such as C5-based petroleum resins (such as distillates such as isoprene, 1,3-pentadiene, cyclopentadiene, methylbutene, and pentene). C9-based petroleum resin (aromatic petroleum resin obtained by polymerizing fractions such as α-methylstyrene, o-vinyltoluene, m-vinyltoluene, and p-vinyltoluene), C5C9 Examples include copolymerized petroleum resins.

The glass transition temperature Tgr (°C) of the thermoplastic resin is preferably 40°C to 120°C, preferably 45°C to 115°C, more preferably 50°C to 110°C. By setting the glass transition temperature Tgr of the thermoplastic resin to 40° C. or higher, dry grip performance is improved, which is preferable. Also. It is preferable to lower the temperature to 120° C. or lower because it improves wear resistance.

In the present specification, among the rubber components consisting of styrene-butadiene rubber or styrene-butadiene rubber and other diene-based rubber, the diene-based rubber containing the largest amount (i.e., styrene-butadiene rubber or other diene-based rubber) The glass transition temperature is Tgp (°C). The difference between the glass transition temperature Tgr (°C) of the thermoplastic resin and the glass transition temperature Tgp (°C) of the diene rubber that is contained most in the thermoplastic resin is 100°C or more. By setting the difference Tgr-Tgp to 100°C or more, excellent wear resistance can be achieved. The difference in glass transition temperature Tgr-Tgp is preferably 105°C or higher, more preferably 110°C or higher. In this specification, the glass transition temperature of diene rubber and thermoplastic resin is determined by measuring a thermogram using differential scanning calorimetry (DSC) at a heating rate of 20°C/min, and is defined as the temperature at the midpoint of the transition region. shall be measured.

As used herein, the plasticizer refers to the oil component and liquid rubber contained in the rubber composition. The oil component refers to the total of the oil blended during the preparation of the rubber composition and the oil contained as an oil extension component in the diene rubber. The oil component may be either natural oil or synthetic oil.

Liquid rubber refers to rubber that is liquid at 23°C. Therefore, it is distinguished from the above-mentioned diene rubber which is solid at 23°C. Examples of the liquid rubber include liquid polybutadiene, liquid polystyrene butadiene, and liquid polyisoprene. The number average molecular weight (Mn) of the liquid rubber is preferably 1,000 or more and less than 50,000, more preferably 5,000 to 40,000, and still more preferably 10,000 to 30,000.

The rubber composition of the present invention has a specific relationship in the temperature dependence curve of each tan δ (tangent loss) with a treated rubber composition obtained by immersing it in toluene and drying it. That is, the half-width in the temperature dependence curve of tan δ of the rubber composition is σbf (°C), the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ is maximum is tan δbf, and the rubber composition is immersed in toluene and dried. The following relational expression ( 1) and (2) are satisfied.
|σbf−σaf|≧4 (1)
|tanδbf−tanδaf|≦0.02 (2)

The temperature dependence curve of tan δ of a rubber composition is calculated by measuring the dynamic viscoelasticity of a cured product of a predetermined shape using a viscoelastic spectrometer at an elongation deformation strain rate of 10 ± 2%, a vibration frequency of 20 Hz, and a temperature of -80 ° C. It can be measured under the condition of 100° C. and obtained as a viscoelastic curve with the measured temperature as the horizontal axis and the loss tangent (tan δ) as the vertical axis. From the obtained temperature dependence curve of tan δ, the thickest value (peak value) of tan δ and the temperature at that time (peak temperature) are determined. The half width σbf of tan δ is determined as the difference between the temperature on the high temperature side and the temperature on the low temperature side when tan δ becomes half of the peak value. Furthermore, the value of tan δ at a temperature 90° C. higher than the peak temperature is determined as tan δbf.

A treated rubber composition obtained by immersing a rubber composition in toluene and drying it is prepared by immersing a cured product of the rubber composition in toluene and drying it. That is, a 2 mm thick sheet (approximately 30 g) obtained by vulcanizing the rubber composition at 160 ° C. for 25 minutes is immersed in 200 ml of toluene and left at room temperature (23 ° C.) for 48 hours. The thermoplastic resin and plasticizer were dissolved and removed. Next, the sheet taken out was immersed in 200 ml of acetone and left to stand at room temperature (23° C.) for 48 hours, thereby replacing toluene with acetone. Thereafter, the sheet taken out is dried at room temperature (23° C.) for 48 hours to remove acetone, and a treated rubber composition obtained by immersing in toluene and drying can be obtained.

The temperature dependence curve of tan δ of the treated rubber composition was obtained by measuring the dynamic viscoelasticity of the cured product of the predetermined shape obtained above using a viscoelastic spectrometer at an extensional deformation strain rate of 10 ± 2% and a frequency of 20 Hz. , at a temperature of -80° C. to 100° C., and can be determined as a viscoelastic curve with the measured temperature as the horizontal axis and the loss tangent (tan δ) as the vertical axis. From the temperature dependence curve of tan δ of the obtained treated rubber composition, the thickest value (peak value) of tan δ and the temperature at that time (peak temperature) are determined. The half width σaf of tan δ is determined as the difference between the temperature on the high temperature side and the temperature on the low temperature side when tan δ becomes half of the peak value. Furthermore, the value of tan δ at a temperature 90° C. higher than the peak temperature is determined as tan δaf.

The half-value width σbf of tan δ of the rubber composition and the half-value width σaf of tan δ of the treated rubber composition are such that the difference between them |σbf−σaf| is 4°C or more, preferably 6°C to 20°C, more preferably 6°C to The temperature is 15°C. By setting the difference |σbf−σaf| within such a range, wear resistance can be improved without deteriorating wet performance. Rubber compositions that satisfy the difference |σbf - σaf| of 4°C or more have a large difference from the glass transition temperature of the thermoplastic resin. It can be prepared by optionally blending a plasticizer to satisfy a specific mass ratio.

The tan δ value tan δbf at a temperature 90° C. higher than the peak temperature at which the tan δ of the rubber composition is maximum and the tan δ value tan δaf at a temperature 90° C. higher than the peak temperature at which the tan δ of the rubber composition after treatment is the maximum are the difference between these. |tanδbf−tanδaf| is 0.02 or less, preferably 0.015 or less. By setting the difference |tanδbf−tanδaf| within such a range, wear resistance can be improved without deteriorating low rolling resistance. A rubber composition satisfying the difference |tan δbf - tan δaf| of 0.02 or less can be prepared by containing a diene rubber and a thermoplastic resin that have good mutual affinity. For example, in a rubber composition containing a thermoplastic resin having low compatibility with diene rubber, tan δbf becomes large, and the difference |tan δbf - tan δaf| exceeds 0.02. As a result, tan δ at 60° C., which is an index of rolling resistance, increases.

In addition to the above-mentioned ingredients, the rubber composition includes, in accordance with a conventional method, vulcanizing or crosslinking agents, vulcanization accelerators, anti-aging agents, processing aids, thermosetting resins, etc. commonly used in tire rubber compositions. Various compounding agents can be blended. Such compounding agents can be kneaded in a conventional manner to form a rubber composition, which can be used for vulcanization or crosslinking. The amounts of these compounding agents can be any conventional and common amounts as long as they do not contradict the purpose of the present invention. The rubber composition can be prepared by mixing the above components using a known rubber kneading machine such as a Banbury mixer, kneader, roll, etc.

The rubber composition is suitable for forming a tread portion and a side portion of a tire, and is particularly suitable for forming a tread portion of a tire. The tire thus obtained can achieve higher levels of wear resistance, low rolling resistance, wet performance, and on-snow performance than conventional levels.

The present invention will be further explained below with reference to Examples, but the scope of the present invention is not limited to these Examples.

In preparing 16 types of rubber compositions (Standard Example, Examples 1-9, Comparative Examples 1-6) having the common additive formulation shown in Table 3 and the formulation shown in Tables 1-2, each The components except sulfur and the vulcanization accelerator were weighed and kneaded for 5 minutes in a 1.7 liter internal Banbury mixer, and then the masterbatch was discharged from the mixer and cooled to room temperature. This masterbatch was subjected to the same Banbury mixer, and sulfur and a vulcanization accelerator were added and mixed to obtain a rubber composition. The additive formulations in Table 3 are expressed in parts by mass based on 100 parts by mass of the rubber components listed in Tables 1 and 2.

In addition, in Tables 1 and 2, the total amount of thermoplastic resin and plasticizer (oil and liquid rubber) is calculated and recorded in the "Resin + Plasticizer" column, and the thermoplastic resin and plasticizer are calculated based on the total amount of thermoplastic resin and plasticizer. The mass proportion of the resin was calculated and recorded in the "Resin mass proportion" column. Furthermore, regarding the rubber compositions of the above-mentioned Examples and Comparative Examples, the difference Tgr between the glass transition temperature Tgp (°C) of the diene rubber having the highest content in the rubber component and the glass transition temperature Tgr (°C) of the thermoplastic resin -Tgp was calculated and recorded in the column of "Difference Tgr - Tgp" in Tables 1 and 2.

Measurement of tan δ temperature dependence curve and half width σbf, tan δ bf of rubber composition The rubber compositions obtained above were each vulcanized at 160°C for 20 minutes in a mold with a predetermined shape, and the dynamic viscoelasticity (loss A sample for evaluation of tangent (tan δ) was prepared. Using the obtained evaluation sample, tan δ was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under the conditions of an extensional deformation strain rate of 10 ± 2%, a vibration frequency of 20 Hz, and a temperature of -80°C to 100°C. Then, a tan δ temperature dependence curve from −80° C. to 100° C. was created with the measured temperature on the horizontal axis and the loss tangent (tan δ) on the vertical axis. From the obtained temperature dependence curve of tan δ, the thickest value (peak value) of tan δ and the temperature at that time (peak temperature) were determined. The half width σbf of tan δ was determined as the difference between the temperature on the high temperature side and the temperature on the low temperature side when tan δ becomes half of the peak value. Further, the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ shows its peak value was determined as tan δbf.

Measurement of tan δ temperature dependence curve, half width σaf, and tan δ af of the rubber composition after toluene treatment A 2 mm thick sheet obtained by vulcanizing the rubber compositions listed in Tables 1 and 2 at 160° C. for 25 minutes 30g) was immersed in 200ml of toluene and allowed to stand at room temperature (23°C) for 48 hours to dissolve and remove the thermoplastic resin and plasticizer. Next, the sheet taken out was immersed in 200 ml of acetone and left to stand at room temperature (23° C.) for 48 hours, thereby replacing toluene with acetone. Thereafter, the removed sheet was dried at room temperature (23°C) for 48 hours to remove acetone, and the treated rubber composition was immersed in toluene and dried to evaluate the dynamic viscoelasticity (loss tangent tan δ). A sample was prepared.

Using the evaluation sample of the treated rubber composition obtained above, using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., an elongation deformation strain rate of 10 ± 2%, a frequency of 20 Hz, and a temperature of -80 ° C. Tan δ was measured under the condition of 100° C., and a tan δ temperature dependence curve from −80° C. to 100° C. was created with the horizontal axis representing the measurement temperature and the vertical axis representing the loss tangent (tan δ). From the obtained temperature dependence curve of tan δ, the thickest value (peak value) of tan δ and the temperature at that time (peak temperature) were determined. The half width σaf of tan δ of the treated rubber composition was determined as the difference between the temperature on the high temperature side and the temperature on the low temperature side when tan δ becomes half of the peak value. Further, the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ of the treated rubber composition shows its peak value was determined as tan δaf.

|σbf-σaf| is calculated from the half-value width σbf of tan δ of the rubber composition obtained above and the half-value width σaf of tan δ of the rubber composition after treatment, and the "difference |σbf-σaf|" in Tables 1 and 2 is calculated. It is written in the column. In addition, |tanδbf−tanδaf| is calculated from the tanδ value tanδbf at a temperature 90°C higher than the tanδ peak temperature of the rubber composition and the tanδ value tanδaf at a temperature 90°C higher than the tanδ peak temperature of the rubber composition after treatment. , is described in the column "Difference |tan δbf - tan δaf|" in Tables 1 and 2.

The rubber composition obtained above was used for a tire tread to vulcanize and mold a pneumatic tire of size 205/55R16, and its abrasion resistance, wet performance, rolling resistance, and on-snow performance were measured by the following methods.

Wear resistance The obtained tire was assembled onto a wheel with a standard rim size, and mounted on a rolling resistance tester equipped with a drum with a radius of 854 mm, under the conditions of an air pressure of 210 kPa, a load of 100 N, a speed of 80 km/h, and a drum surface temperature of 20°C. After a 30-minute preliminary run, a 20,000 km running test was conducted at a speed of 100 km/h, and the amount of wear on the tread land portion was measured. The evaluation results were obtained by calculating the reciprocal of the measured value and using the standard example as an index of 100, and are shown in the "Abrasion Resistance" column of Tables 1 and 2. The larger the index, the smaller the amount of wear and the better the wear resistance.

Wet performance The obtained tire was attached to a standard rim and mounted on a test vehicle equipped with ABS with a displacement of 2000 cc, and the air pressure of the front tire and rear tire was set to 220 kPa. The test vehicle was run on an asphalt road surface sprinkled with water at a depth of 2.0 to 3.0 mm, and the braking stopping distance from a speed of 100 km/h was measured. The obtained results were calculated by calculating the reciprocal of each, and were set as an index with the value of the standard example as 100, and are shown in the "wet performance" column of Tables 1 and 2. The larger the index, the shorter the braking and stopping distance and the better the wet performance.

Rolling Resistance The obtained tire was assembled onto a wheel with a standard rim size and mounted on a rolling resistance tester equipped with a drum with a radius of 854 mm, under the conditions of an air pressure of 210 kPa, a load of 100 N, a speed of 80 km/h, and a drum surface temperature of 20°C. After a preliminary run of 30 minutes, rolling resistance was measured under the same conditions. The evaluation results are shown in the "Rolling Resistance" column of Tables 1 and 2 using the reciprocal of the measured value as an index with the standard example as 100. It means that the larger this index is, the lower the rolling resistance is.

Performance on Snow The obtained tire was attached to a standard rim and mounted on a test vehicle with a displacement of 2000 cc, and the air pressure of the front tire and rear tire was set to 220 kPa. The vehicle was driven around a 2.6km test course in snowy conditions, and three expert panelists evaluated the handling stability using a score system. The obtained results were expressed as an index with the value of the standard example as 100, and are shown in the "Snow performance" column of Tables 1 and 2. The larger this index is, the higher the evaluation score for steering stability when driving on snow, and the better the performance on snow.

The types of raw materials used in Tables 1 and 2 are shown below.
・NR: Natural rubber, TSR20, glass transition temperature -65℃
・SBR-1: Terminal-modified styrene-butadiene rubber with polyorganosiloxane structure, Nipol NS612 manufactured by Nippon Zeon, glass transition temperature -61°C, styrene content 15% by mass, vinyl content 31%, non-oil extended product. SBR-2: Terminal-modified styrene-butadiene rubber having a polyorganosiloxane structure, Nipol NS616 manufactured by Nippon Zeon, glass transition temperature -23°C, styrene content 22% by mass, vinyl content 67%, non-oil extended product/SBR -3: Terminal-modified styrene-butadiene rubber with polyorganosiloxane structure, Yokohama Rubber Co., Ltd. prototype SBR, glass transition temperature -80°C, styrene content 6% by mass, vinyl content 15%, non-oil extended product/BR: Butadiene rubber, Nipol BR1220 manufactured by Nippon Zeon Co., Ltd., glass transition temperature is -105°C
・Carbon black: Seast 7HM manufactured by Tokai Carbon Co., Ltd.
・Silica: Solvey Zeosil 1165MP, nitrogen adsorption specific surface area 159 m ² /g
・Coupling agent: Silane coupling agent, Evonik Degussa Si69
・Resin-1: C9 petroleum resin, Neopolymer S100 manufactured by ENEOS, glass transition temperature 58°C
・Resin-2: Aromatic modified terpene resin, YS resin TO-105 manufactured by Yasuhara Chemical Co., Ltd., glass transition temperature is 57°C
・Resin-3: Indene resin, FMR0150 manufactured by Mitsui Chemicals, glass transition temperature 89°C
・Resin-4: Phenol-modified terpene resin, Tamanol 803L manufactured by Arakawa Chemical Industry Co., Ltd., glass transition temperature is 95°C
・Liquid rubber: manufactured by Evonik, POLYVEST ^(R) ST-E60
・Oil: Shell Lubricants Japan Extract No. 4 S

The types of raw materials used in Table 3 are shown below.
・Anti-aging agent: VULANOX 4020 manufactured by LANXESS
・Wax: OZOACE-0015A manufactured by NIPPON SEIRO
・Sulfur: Sulfax 5 manufactured by Tsurumi Chemical Industry Co., Ltd.
・Vulcanization accelerator: Noxeler CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

As is clear from Tables 1 and 2, it was confirmed that the rubber compositions of Examples 1 to 9 were excellent in abrasion resistance, wet performance, low rolling resistance, and performance on snow.

As is clear from Table 1, the rubber composition of Comparative Example 1 has a low ratio of less than 65% by mass of the thermoplastic resin to the total of the thermoplastic resin and plasticizer, and the difference |σbf−σaf| is less than 4°C. Rolling resistance cannot be improved beyond the standard example, and wet performance deteriorates.
In the rubber composition of Comparative Example 2, the total amount of thermoplastic resin and plasticizer was less than 20 parts by mass, and the difference |σbf - σaf| was less than 4°C, so the low rolling resistance could not be improved more than that of the standard example. , wet performance deteriorates.
In the rubber composition of Comparative Example 3, the difference |tanδbf−tanδaf| exceeds 0.02, so wet performance, rolling resistance, and on-snow performance deteriorate.
In the rubber composition of Comparative Example 4, the difference |tanδbf−tanδaf| exceeds 0.02, so the rolling resistance deteriorates.
In the rubber composition of Comparative Example 5, the difference Tgr - Tgp between the glass transition temperature Tgp of the diene rubber having the highest content and the glass transition temperature Tgr of the thermoplastic resin is less than 100°C, so it has excellent abrasion resistance, rolling resistance, and snow resistance. Performance deteriorates.
In the rubber composition of Comparative Example 6, the ratio of the thermoplastic resin to the total of the thermoplastic resin and the plasticizer is less than 65% by mass, so the wet performance deteriorates.

The present disclosure includes the following inventions.
Invention [1] 100 parts by mass of a rubber component containing styrene-butadiene rubber and optionally other diene rubber, 20 to 150 parts by mass of a white filler, and a total of 20 parts by mass or more of a thermoplastic resin and optionally a plasticizer. A rubber composition containing styrene-butadiene rubber or The difference Tgr - Tgp between the glass transition temperature Tgp (°C) of the other diene rubber and the glass transition temperature Tgr (°C) of the thermoplastic resin is 100°C or more, and the temperature dependence curve of tan δ of the rubber composition is Temperature dependence of tan δ of the treated rubber composition obtained by immersing and drying the rubber composition in toluene, where the half width is σbf (°C) and the value of tan δ at a temperature 90° C. higher than the peak temperature at which tan δ is maximum is tan δbf. It is characterized by satisfying the following relational expressions (1) and (2), where the half-width in the sex curve is σaf (°C), and the value of tanδ at a temperature 90°C higher than the peak temperature at which tanδ is maximum is tanδaf. rubber composition.
|σbf−σaf|≧4 (1)
|tanδbf−tanδaf|≦0.02 (2)
Invention [2] The other diene rubber is selected from isoprene rubber and butadiene rubber, and out of 100% by mass of the rubber component, the isoprene rubber is 0 to 15% by mass and the butadiene rubber is 5 to 45% by mass. , the rubber composition according to invention [1], wherein the styrene-butadiene rubber is 40 to 95% by mass.
Invention [3] The rubber composition according to Invention [1] or [2], wherein at least one terminal of the styrene-butadiene rubber is modified with a functional group.
Invention [4] The Tgr is 40 to 120°C, the thermoplastic resin is a resin consisting of at least one selected from terpene, modified terpene, rosin, rosin ester, C5 component, C9 component, and two or more of these resins. The rubber composition according to any one of inventions [1] to [3], wherein at least a portion of the heavy bonds are at least one selected from the group consisting of hydrogenated resins.

Claims (4)

100 parts by mass of a rubber component containing styrene-butadiene rubber and optionally other diene rubber, 20 to 150 parts by mass of a white filler, and a total of 20 to 100 parts by mass of a thermoplastic resin and optionally a plasticizer. A rubber composition, in which the ratio of the thermoplastic resin to the total of the thermoplastic resin and the plasticizer is 65% by mass or more, and the rubber composition has the largest content among the rubber components, such as styrene-butadiene rubber or other diene rubber. The difference Tgr - Tgp between the glass transition temperature Tgp (°C) of the rubber and the glass transition temperature Tgr (°C) of the thermoplastic resin is 100°C or more, and the half-width in the temperature dependence curve of tan δ of the rubber composition is σbf. (°C), the value of tanδ at a temperature 90°C higher than the peak temperature at which tanδ is maximum is defined as tanδbf, and the half of the temperature dependence curve of tanδ of the treated rubber composition obtained by immersing the rubber composition in toluene and drying it. A rubber composition that satisfies the following relational expressions (1) and (2), where the value range is σaf (°C) and the value of tanδ at a temperature 90°C higher than the peak temperature at which tanδ is maximum is tanδaf. .
|σbf−σaf|≧4 (1)
|tanδbf−tanδaf|≦0.02 (2) The other diene rubber is selected from isoprene rubber and butadiene rubber, and out of 100% by mass of the rubber component, the isoprene rubber is 0 to 15% by mass, the butadiene rubber is 5 to 45% by mass, and the styrene-butadiene rubber is 0 to 15% by mass. The rubber composition according to claim 1, characterized in that the rubber content is 40 to 95% by mass. 3. The rubber composition according to claim 1, wherein at least one end of the styrene-butadiene rubber is modified with a functional group. The Tgr is 40 to 120°C, and the thermoplastic resin is a resin consisting of at least one selected from terpene, modified terpene, rosin, rosin ester, C5 component, and C9 component, and at least one of the double bonds of these resins. The rubber composition according to claim 1 or 2, characterized in that the rubber composition is at least one member selected from the group consisting of partially hydrogenated resins.