CN118772493A

CN118772493A - Rubber composition and tire

Info

Publication number: CN118772493A
Application number: CN202410314039.4A
Authority: CN
Inventors: 姜岚; 富崎由佳理
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2023-04-06
Filing date: 2024-03-19
Publication date: 2024-10-15

Abstract

The invention provides a rubber composition and a tire which can exert physical property change reversible with water. The present invention relates to a rubber composition containing a rubber component, a filler and a rosin compound, wherein the rubber composition satisfies the following formulas (1) to (2): (1) Tan delta when wet/tan delta when dry >1.00, (2) E when wet/E when dry <1.00, in the formulas (1), (2), tan delta and E are loss tangent and complex elastic modulus measured under conditions of 30 ℃ temperature, 10% initial strain, 1% dynamic strain, 10Hz frequency, and stretching mode.

Description

Rubber composition and tire

Technical Field

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

Background

Regarding articles such as tires, various materials have been studied to impart various properties, and improvement of properties has been desired. Conventionally, a technique for improving grip performance and abrasion resistance has been sought (patent document 1, etc.).

[ Prior Art literature ]

[ Patent literature ]

Patent document 1: JP-A2008-285524

Disclosure of Invention

[ Problem to be solved by the invention ]

The present invention aims to solve the above problems and to provide a rubber composition and a tire which can exhibit a change in physical properties reversibly accompanying water.

[ Problem for solving the problem ]

The present invention relates to a rubber composition containing a rubber component, a filler and a rosin compound, which satisfies the following formulas (1) to (2).

(1) Tan delta on water wetting/tan delta on drying >1.00

(2) E on wetting/E on drying <1.00

(Tan. Delta. And E. In the formulae (1) and (2), tan. Delta. And E. Are loss tangent and complex elastic modulus measured under conditions of 30 ℃ C. Initial strain 10%, dynamic strain 1%, frequency 10Hz, and stretching mode.)

[ Effect of the invention ]

The present invention provides a rubber composition which contains a rubber component, a filler and a rosin compound and satisfies the above-mentioned formulas (1) to (2), and thus can exhibit a change in physical properties reversibly with water.

Drawings

FIG. 1 is an example of IR spectra of gum rosin (gum rosin), gum rosin Na, and gum rosin Zn.

Detailed Description

< Rubber composition >

The present invention is a rubber composition comprising a rubber component, a rosin compound and a filler, and satisfying the following formulas (1) to (2).

(1) Tan delta on water wetting/tan delta on drying >1.00

(2) E on wetting/E on drying <1.00

Although the reason for obtaining the above-described action effect is not clear, it is presumed that the following mechanism is based.

If a rosin compound such as a rosin metal salt is blended in the rubber composition, the glass transition temperature Tg is thought to be high due to aggregation by bonding such as strong ionic bonds during drying of the rubber composition, and the rubber mixed with the rosin compound becomes difficult to move.

On the other hand, when the rubber composition is wet with water, bonds such as ionic bonds are dissociated, tg becomes low, and the rubber mixed with the rosin compound becomes easy to move.

Therefore, by compounding a rosin compound such as a rosin metal salt, a rubber composition satisfying the above-mentioned formulas (1) and (2) can be obtained, and a reversible change in physical properties with water can be exhibited.

As described above, the present invention solves the problem (object) of exhibiting a change in physical properties reversibly with water by configuring the rubber composition to contain a rubber component, a rosin compound and a filler and to satisfy the formula (1) 'tan δ when wet with water/tan δ when dry > 1.00', and the formula (2) 'E when wet with water/E < 1.00'. That is, the parameters of the formulae (1) to (2) are not limited to the problem (object), and the problem of the present invention is to exhibit a physical property change reversibly with water, and as a solution means for the problem, a configuration satisfying the parameters is set.

In the present specification, tan δ and E of a rubber composition refer to tan δ and E of a crosslinked rubber composition when the rubber composition is crosslinkable, for example, tan δ and E of a rubber composition after vulcanization (after crosslinking) when the rubber composition contains a crosslinkable rubber such as diene rubber and sulfur. The tan δ and E are values obtained by performing a viscoelastic test on a rubber composition (crosslinked rubber composition).

The rubber composition can exhibit a reversible physical property change with water, for example, a loss tangent (tan δ) and a complex elastic modulus (e×) change reversibly with water.

In the present specification, the reversible change of the loss tangent (tan δ) and the complex elastic modulus (E) with water means that the tan δ and E of the rubber composition (after vulcanization) are reversibly increased or decreased by the presence of water. For example, when the temperature is changed from drying to wetting with water to drying, the tan δ and E may be changed reversibly, and the tan δ and E may not be the same at the time of the preceding drying and the time of the following drying, or the tan δ and E may be the same at the time of the preceding drying and the time of the following drying.

In the present specification, tan δ and E when dried refer to tan δ and E of a rubber composition in a dry state, specifically, tan δ and E of a rubber composition dried by the method described in examples.

In the present specification, tan δ and E in the case of water wetting refer to tan δ and E of a rubber composition in a state of being wetted with water, specifically, tan δ and E of a rubber composition wetted with water by the method described in examples.

In the present specification, tan δ and E of a rubber composition are measured under conditions of a temperature of 30 ℃, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and a stretching mode.

The rubber composition satisfies the following formula (1).

(1) Tan delta on water wetting/tan delta on drying >1.00

(In formula (1), tan. Delta. Is the loss tangent measured under conditions of a temperature of 30 ℃, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and a stretching mode.)

The tan δ in water wetting/tan δ in drying is preferably 1.04 or more, preferably more than 1.06, more preferably 1.07 or more, further preferably more than 1.07, further more preferably 1.09 or more, particularly preferably more than 1.14, particularly preferably more than 1.19, and particularly preferably 1.20 or more. The upper limit of tan δ in water wetting/tan δ in drying is not particularly limited, but is preferably 1.80 or less, more preferably 1.70 or less, further preferably 1.65 or less, and particularly preferably 1.60 or less. Within the above range, effects can be suitably obtained.

The tan δ of the rubber composition upon water wetting is preferably 0.15 or more, more preferably 0.20 or more, further preferably 0.22 or more, particularly preferably 0.24 or more, and particularly preferably 0.28 or more. The upper limit of tan δ at the time of water wetting is preferably 0.50 or less, more preferably 0.37 or less, further preferably 0.31 or less, particularly preferably 0.30 or less. Within the above range, effects can be suitably obtained.

The rubber composition satisfies the following formula (2).

(2) E on wetting/E on drying <1.00

(In formula (2), E is complex elastic modulus measured under conditions of 30 ℃ temperature, 10% initial strain, 1% dynamic strain, 10Hz frequency and stretching mode.)

The E in wet/dry state is preferably 0.98 or less, more preferably 0.97 or less, further preferably less than 0.97, further preferably less than 0.96, particularly preferably less than 0.93, particularly preferably 0.92 or less, and particularly preferably 0.91 or less. The lower limit of E in wet/dry is preferably 0.80 or more, more preferably 0.83 or more, still more preferably 0.85 or more, and particularly preferably 0.87 or more. Within the above range, effects can be suitably obtained.

The E of the rubber composition upon water wetting is preferably 12.10MPa or less, more preferably 9.33MPa or less, even more preferably 8.40MPa or less, even more preferably 8.20MPa or less, particularly preferably 5.00MPa or less, and particularly preferably 4.82MPa or less. The lower limit of E in water wetting is preferably 3.00MPa or more, more preferably 3.50MPa or more, and even more preferably 4.00MPa or more. Within the above range, effects can be suitably obtained.

The change in tan δ and E of the rubber composition, which are reversible with water, represented by the above formulas (1) and (2), can be achieved by compounding a rosin compound such as a rosin metal salt. Specifically, for example, when a rosin compound such as a rosin metal salt is compounded, the glass transition temperature Tg becomes high due to aggregation by strong ionic bonds or the like at the time of drying of the rubber composition, and the rubber mixed with the rosin compound becomes difficult to move, whereas when the rubber composition is wet with water, the ionic bonds are dissociated, tg becomes low, and the rubber mixed with the rosin compound becomes easy to move. As a result, it is considered that the increase and decrease in tan δ occur during water wetting, and the decrease and increase in tan δ occur during drying.

The tan δ at the time of drying may be adjusted by the kind and amount of chemicals (in particular, rubber component, filler, plasticizer, sulfur, vulcanization accelerator, silane coupling agent) compounded in the rubber composition, and for example, tan δ at the time of drying tends to be large by using plasticizers (various resins and the like) having low compatibility with the rubber component, using non-modified polymers, increasing the amount of filler, increasing the plasticizer, reducing sulfur accelerator, or reducing silane coupling agent.

The E in the drying process may be adjusted by the type and amount of chemicals (in particular, rubber component, filler, plasticizer) blended in the rubber composition, and for example, the E in the drying process tends to be large by decreasing the amount of plasticizer or increasing the amount of filler.

Regarding tan δ and E in water wetting, for example, when a rosin compound such as a rosin metal salt is compounded, ionic bonds are dissociated in water wetting, and the rubber is easily moved, and as a result, tan δ tends to be increased and E tends to be decreased as compared with that in drying.

The amounts of the chemicals to be blended in the rubber composition may be adjusted by the types and amounts of the chemicals to be blended in the rubber composition, and for example, the same tendencies may be obtained in the wet tan δ and E by using the same means and methods as the above-described methods for adjusting the dry tan δ and dry tan δ.

Preferably, the rubber composition satisfies the following formula, tan δ when wet with water/tan δ when dry (hereinafter also referred to as index 1) and E when wet with water/E when dry (hereinafter also referred to as index 2).

Index 1/index 2>1.05

Index 1/index 2 ((tan δ in water wet/tan δ in dry)/(E in water wet/E in dry)) is preferably 1.06 or more, more preferably greater than 1.10, further preferably 1.11 or more, more preferably 1.20 or more, particularly preferably greater than 1.20, even more preferably 1.22 or more, particularly preferably greater than 1.28, and particularly preferably 1.30 or more. The upper limit of index 1/index 2 is preferably 1.50 or less, more preferably 1.40 or less, and further preferably 1.38 or less. Within the above range, effects can be suitably obtained.

Although the reason why the better effect can be obtained by adjusting to index 1/index 2>1.05 is not clear, it is considered that: when index 1/index 2 shows a large value, the rubber composition becomes difficult to move when it is dried and the rubber composition becomes easy to move when it is wet with water, and as a result, the physical property change with water is remarkably exhibited.

By adjusting tan δ at dry time, E at dry time, tan δ at wet time, and E at wet time, index 1 (tan δ at wet time/tan δ at dry time), and index 2 (E at wet time/E at dry time) can be appropriately adjusted using the above-described method.

The rubber composition contains a rubber component.

Here, the rubber component is a component contributing to crosslinking, and is generally a polymer having a weight average molecular weight (Mw) of 1 ten thousand or more, and the polymer component not extracted with acetone corresponds to the rubber component. The rubber component is in a solid state at room temperature (25 ℃).

The weight average molecular weight of the rubber component is preferably 5 ten thousand or more, more preferably 15 ten thousand or more, further preferably 20 ten thousand or more, particularly preferably 27 ten thousand or more, and further preferably 200 ten thousand or less, more preferably 150 ten thousand or more, further preferably 100 ten thousand or less. When the amount is within the above range, the effect tends to be more effectively obtained.

In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be obtained by conversion from standard polystyrene based on measured values obtained by Gel Permeation Chromatography (GPC) (GPC-8000 series manufactured by Tosoh corporation, detector: differential refractometer, column chromatography: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh corporation).

The rubber component that can be used in the above-mentioned rubber composition may be an unmodified rubber or may be a modified rubber.

Examples of the modified rubber include a rubber having a functional group capable of interacting with a filler such as silica. For example, there may be mentioned: a terminal-modified rubber in which at least one terminal of the rubber is modified with a compound (modifier) having the above-mentioned functional group (terminal-modified rubber having the above-mentioned functional group at the terminal), a main chain-modified rubber in which the above-mentioned functional group is present in the main chain, a main chain-terminal-modified rubber in which the above-mentioned functional group is present in the main chain and the terminal (for example, a main chain-terminal-modified rubber in which the above-mentioned functional group is present in the main chain and at least one terminal is modified with the above-mentioned modifier), a terminal-modified rubber in which a hydroxyl group, an epoxy group are introduced, or the like is modified (coupled) by a polyfunctional compound having 2 or more epoxy groups in the molecule.

Examples of the functional group include: amino, amido, silyl, alkoxysilyl, isocyanate, imino, imidazolyl, ureido, ether, carbonyl, oxycarbonyl, mercapto, thioether (thio) group, disulfide (disulfide group), sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazine (hydrazo group), azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxy, epoxy, and the like. It should be noted that these functional groups may have a substituent. Among them, amino group (preferably amino group having hydrogen atom replaced with alkyl group having 1 to 6 carbon atoms), alkoxy group (preferably alkoxy group having 1 to 6 carbon atoms), alkoxysilyl group (preferably alkoxysilyl group having 1 to 6 carbon atoms) are preferable.

Examples of the rubber component include: diene rubber.

The diene rubber may be: isoprene rubber, butadiene Rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene Rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. The rubber component may be butyl rubber, fluororubber, or the like. They may be used alone, or 2 or more kinds may be used in combination. Further, these rubber components may be subjected to a modification treatment or a hydrogenation treatment, and a filled rubber filled with an oil, a resin, a liquid rubber component or the like may be used. Of these, at least one kind of NR, BR, SBR is preferably contained, at least 2 kinds of NR, BR, SBR are more preferably contained, and NR, BR, and SBR are even more preferably contained.

Examples of the isoprene rubber include Natural Rubber (NR), isoprene Rubber (IR), modified NR, and modified IR. As NR, for example, conventional products in rubber industries such as SIR20, rss#3, and TSR20 can be used. The IR is not particularly limited, and for example, a conventional product in the rubber industry such as IR2200 can be used. The modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and the like, the modified NR includes Epoxidized Natural Rubber (ENR), hydrogenated Natural Rubber (HNR), grafted natural rubber, and the like, and the modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. They may be used alone, or 2 or more kinds may be used in combination.

In the rubber composition, the content of the isoprene-based rubber in 100 mass% of the rubber component is preferably 30 mass% or more, more preferably 40 mass% or more, further preferably 45 mass% or more, and further preferably 70 mass% or less, more preferably 60 mass% or less, further preferably 55 mass% or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The BR is not particularly limited, and for example, a high cis BR having a high cis content, a BR containing syndiotactic polybutadiene crystals, a BR synthesized using a rare earth catalyst (rare earth BR), and the like can be used. They may be used alone, or 2 or more kinds may be used in combination. Among them, BR preferably contains high cis BR having a cis content of 90% by mass or more. The cis content is more preferably 95 mass% or more. The cis content may be measured by infrared absorption spectrometry.

The cis-amount of BR means the cis-amount of BR when BR is 1 species, and means the average cis-amount when BR is plural species.

The average cis-form amount of BR can be calculated by { Σ (content of each br×cis-form amount of each BR) }/total content of all BRs, for example, in 100 mass% of the rubber component, cis-form amount: 90 mass% BR is 20 mass%, cis formula: when 40 mass% of BR is 10 mass%, the average cis-form weight of BR is 73.3 mass% (= (20×90+10×40)/(20+10)).

Further, BR may be any of unmodified BR and modified BR. As the modified BR, a modified BR into which the same functional group as that of the modified rubber is introduced is exemplified. In addition, a hydrogenated butadiene polymer (hydrogenated BR) may be used as BR.

Examples of BR include products of yu xiang co, JSR co, xu chemical co, japan rui Weng Zhushi co.

In the rubber composition, the BR content is preferably 5 mass% or more, more preferably 10 mass% or more, further preferably 15 mass% or more, and further preferably 50 mass% or less, more preferably 30 mass% or less, further preferably 25 mass% or less, based on 100 mass% of the rubber component. When the amount is within the above range, the effect tends to be more effectively obtained.

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. They may be used alone, or 2 or more kinds may be used in combination.

The styrene content of SBR is preferably 5 mass% or more, more preferably 8 mass% or more, and still more preferably 10 mass% or more. The styrene content is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 35 mass% or less. When the amount is within the above range, the effect tends to be more effectively obtained.

In the present specification, the styrene content may be measured by ¹ H-NMR measurement.

The styrene amount of SBR means the styrene amount of SBR when the SBR is 1 type, and means the average styrene amount when the SBR is plural types.

The average styrene content of SBR can be calculated by { Σ (content of each sbr×styrene content of each SBR) } per total SBR content, for example, when SBR having 40 mass% of styrene content is 85 mass% and SBR having 25 mass% of styrene content is 5 mass% in 100 mass% of the rubber component, the average styrene content of SBR is 39.2 mass% (= (85×40+5×25)/(85+5)).

The vinyl bond content of SBR is preferably 10 mass% or more, more preferably 30 mass% or more, further preferably 40 mass% or more, and particularly preferably 41 mass% or more. The vinyl bond content is preferably 70 mass% or less, more preferably 60 mass% or less, and still more preferably 50 mass% or less. When the amount is within the above range, the effect tends to be more effectively obtained.

In the present specification, the vinyl bond amount (1, 2-bonded butadiene unit amount) can be measured by infrared absorption spectrometry.

The vinyl content (1, 2-bonded butadiene unit content) of SBR is the ratio of vinyl bonds (unit: mass%) when the total mass of the butadiene portion in SBR is 100, and vinyl content [ mass% ] +cis content [ mass% ] +trans content [ mass% ] =100 [ mass% ]. The vinyl content of SBR is 1, and the average vinyl content of SBR is plural.

The average vinyl content of SBR may be represented by Σ { the content of each SBR x (100% by mass) ×the styrene content of each SBR [ mass% ] }/Σ { the content of each SBR x (100% by mass) ×the styrene content of each SBR [ mass% ] }, for example, of 100 parts by mass of the rubber component, 40% by mass of the styrene, 30% by mass of the vinyl content of SBR, 15 parts by mass of the styrene content of 25% by mass, 20% by mass of the vinyl content of SBR, and the remaining 10 parts by mass of SBR are 28% by mass (= {75× (100% by mass) ×40% by mass) ×30[ mass%) +15× (100% by mass) ×20% (100% by mass) }/{75× (100% by mass) ×40% by mass) +15× (100% by mass) } 75× (100% by mass% > -25% by mass) } when the rest of the SBR is other than SBR.

SBR may be any of non-denatured SBR and modified SBR. As the modified SBR, a modified SBR having the same functional group as that of the modified rubber introduced therein can be exemplified. In addition, as SBR, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) may be used.

As the SBR, SBR manufactured and sold by, for example, sumitomo chemical corporation, JSR corporation, asahi chemical corporation, japan rayleigh Weng Zhushi corporation, etc. can be used. SBR synthesized by a known method may also be used.

In the rubber composition, the SBR content is preferably 20 mass% or more, more preferably 30 mass% or more, further preferably 40 mass% or more, and further preferably 80 mass% or less, more preferably 60 mass% or less, further preferably 50 mass% or less, based on 100 mass% of the rubber component. When the amount is within the above range, the effect tends to be more effectively obtained.

The rubber composition contains a filler.

In the rubber composition, the filler content Fc (total amount of fillers such as carbon black and silica, parts by mass) preferably satisfies the following formula with respect to 100 parts by mass of the rubber component in view of better effect.

40<Fc<90

The lower limit of Fc is preferably more than 42 parts by mass, more preferably more than 44 parts by mass, and still more preferably 51 parts by mass or more. The upper limit of Fc is preferably 86 parts by mass or less, more preferably less than 85 parts by mass, still more preferably less than 80 parts by mass, and still more preferably less than 75 parts by mass. When the amount is within the above range, the effect tends to be more effectively obtained.

Although the reason why the effect can be better obtained at 40< fc <90 is not clear, it is considered that: in the case of a rubber composition containing a proper amount of filler, the effects that the rubber becomes difficult to move when the rubber composition is dried and the rubber becomes easy to move when the rubber is wet with water can be remarkably obtained, and as a result, the physical property change with water can be remarkably exhibited.

The filler is not particularly limited, and materials known in the rubber field can be used, and examples thereof include inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, alumina, and mica, and biomass charcoal (BIO CHAR); and hardly dispersible fillers. Among them, carbon-derived fillers (carbon-containing fillers) such as carbon black, silica, and the like are preferable from the viewpoint of better effect. The filler may be used alone, or 2 or more kinds may be used in combination.

The carbon black that can be used in the rubber composition is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. As the commercial products, products such as Asahi Carbon co., ltd., cabot Japan co., cabot Japan k.k., to the east asian Carbon co., ltd., to the Tokai Carbon co., ltd., to the lion king corporation, new japanese Carbon co., columbia Carbon black (Columbia Carbon), etc., can be used. They may be used alone, or 2 or more kinds may be used in combination. In addition to conventional carbon black obtained from mineral oil, etc., carbon black obtained from biomass material such as lignin may be used. The regenerated carbon black obtained by decomposing a rubber product, plastic product, or the like containing carbon black such as a tire may be replaced with the same amount of the carbon black as described above.

The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is preferably 50m ²/g or more, more preferably 80m ²/g or more, still more preferably 100m ²/g or more, particularly preferably 114m ²/g or more. The N ₂ SA is preferably 150m ²/g or less, more preferably 130m ²/g or less, and still more preferably 120m ²/g or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The nitrogen adsorption specific surface area of the carbon black may be as defined in JIS K6217-2: 2001.

The dibutyl phthalate oil absorption (DBP) of the carbon black is preferably 40ml/100g or more, more preferably 60ml/100g or more, and still more preferably 70ml/100g or more. The DBP is preferably 200ml/100g or less, more preferably 150ml/100g or less, and still more preferably 100ml/100g or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The DBP of the carbon black can be obtained by the method of JIS K6217-4: 2001.

In the rubber composition, the content of carbon black is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 6 parts by mass or more, and further preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be more effectively obtained.

Examples of silica that can be used in the rubber composition include dry process silica (anhydrous silica) and wet process silica (hydrous silica). Among them, wet-process silica is preferable for the reason of silanol-based. As commercial products, products such as Degussa, roditia, tokyo Cao Guihua Co., ltd (Tosoh Silica Corporation), sorvy Japan, deshan, etc. can be used. They may be used alone, or 2 or more kinds may be used in combination.

As the silica, silica derived from a plant may also be suitably used.

Examples of the silica derived from plants include silica derived from plants containing a silica component. Examples of the plant containing a silica component include rice, corn, sugarcane, horsetail, wheat, barley, rye, coix seed, millet, barnyard grass, mango, and cane. Further, the saccharification residue of the plant containing the silica component may be used. Among these, rice hulls and stalks of rice having a high silica content are preferable, and rice hulls are more preferable. The plant containing the silica component may be changed into ash by combustion treatment or may be subjected to carbonization treatment.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica is preferably 50m ²/g or more, more preferably 100m ²/g or more, still more preferably 150m ²/g or more, particularly preferably 175m ²/g or more. The upper limit of N ₂ SA of silica is not particularly limited, but is preferably 350m ²/g or less, more preferably 300m ²/g or less, and still more preferably 250m ²/g or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The silica N ₂ SA is a value measured by the BET method according to ASTM D3037-93.

In the rubber composition, the content of silica is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and still more preferably 45 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, and still more preferably 80 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The content of the plant-derived silica and the content of the rice hull silica are preferably in the same range.

Examples of the hardly dispersible filler include microfibrillated plant fibers, short-fiber-like cellulose, and gel-like compounds. Among them, microfibrillated plant fibers are preferable.

As the microfibrillated plant fiber, cellulose microfibrils are preferable from the viewpoint of obtaining good reinforcement. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples thereof include biomass as a resource such as fruits, grains, and root vegetables, wood, bamboo, hemp, jute, kenaf, waste biomass such as pulp, paper, cloth, crop waste, food waste, and sewage sludge obtained from these materials, unused biomass such as rice straw, wheat straw, and meta-valve material, and materials derived from cellulose produced by ascidians, acetic acid bacteria, and the like. The microfibrillated plant fibers may be used in 1 kind, or may be used in combination of more than 2 kinds.

In the present specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, and more typically refer to cellulose fibers having a microstructure having an average fiber diameter of 500nm or less, which is formed by aggregation of cellulose molecules. Typical cellulose microfibrils are formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

When the rubber composition contains a hardly dispersible filler, the content of the hardly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, further preferably 20 parts by mass or less, particularly preferably 10 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

In the rubber composition, the silica content in the filler (100 mass%) is preferably 50 mass% or more, more preferably 80 mass% or more, and still more preferably 85 mass% or more. The upper limit is not particularly limited, and may be 100% by mass, preferably 95% by mass or less, more preferably 93% by mass or less, and still more preferably 90% by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent.

The silane coupling agent is not particularly limited, and those known in the rubber field can be used, and examples thereof include: sulfides such as bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide; mercapto systems such as 3-mercaptopropyl trimethoxysilane, 2-mercaptoethyl triethoxysilane, NXT and NXT-Z manufactured by Michigan (Momentive) corporation; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino systems such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane; glycidoxy systems such as gamma-glycidoxypropyl triethoxysilane and gamma-glycidoxypropyl trimethoxysilane; nitro systems such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; chlorine (radical) systems such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. As the commercial products, products such as Degussa (Degussa), michigan (Momentive), silicon company of Shin-Etsu Silicone co., ltd.), tokyo chemical industry co., azmax, and dori-dakonin are available. They may be used alone, or 2 or more kinds may be used in combination.

In the rubber composition, the content of the silane coupling agent is preferably 0.1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more, and particularly preferably 8 parts by mass or more, based on 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, further preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The rubber composition contains a rosin compound as a plasticizer.

In the present specification, the rosin compound means rosin, a rosin derivative derived from rosin, or a rosin metal salt (rosin acid metal salt).

The rosin compound may be used alone, or 2 or more kinds may be used in combination.

The glass transition temperature (Tg) of the rosin compound is preferably 20 ℃ or higher, more preferably 50 ℃ or higher, still more preferably 70 ℃ or higher, particularly preferably 80 ℃ or higher. The upper limit is not particularly limited, and may be 1000℃or less, or 800℃or less, or 700℃or less, for example. Within the above range, the tire performance such as wet grip performance tends to be more favorably obtained.

In the present specification, the glass transition temperature (Tg) of a raw material such as a rosin compound can be measured by Differential Scanning Calorimetry (DSC) under a temperature rise rate of 10℃per minute in accordance with JIS K7121-1987.

In the rubber composition, the content of the rosin compound (total amount of rosin metal salt, rosin, etc.) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The rosin is obtained by refining resin acids contained in pine, and can be classified into gum rosin, wood rosin, and tall oil rosin. The main components of the rosin are abietic acid, neoabietic acid, levopimaric acid, dehydroabietic acid (dehydroabietic acid), dextrorotatory pimaric acid and other abietic acids.

Examples of the rosin derivative include disproportionated rosin, hydrogenated rosin, dehydrogenated rosin, polymerized rosin, rosin alcohol, rosin amine, unsaturated acid-modified rosin, and rosin esters thereof.

Among the rosin compounds, rosin metal salts (rosin acid metal salts) are preferable from the viewpoint of better obtaining effects.

The rosin metal salt is, for example, a salt of rosin acid and a metal such as a salt of rosin acid and a monovalent, divalent, trivalent or tetravalent polyvalent metal. Specifically, na salt, K salt, ca salt, ba salt, sr salt, al salt, zn salt, cu salt, mg salt of rosin (abietic acid) can be mentioned; reactants of other metal compounds with rosin, and the like. Among them, sodium abietate, zinc abietate, and potassium abietate are preferable from the viewpoint of better effect.

Although the reason why the effect can be obtained better in the case of rosin metal salts such as sodium rosin acid, zinc rosin acid, potassium rosin acid, etc. is not clear, it is considered that: when the rosin metal salt is used, the rubber composition becomes difficult to move during drying and the rubber tends to move easily during wetting with water, and as a result, the physical property change with water is remarkably exhibited.

The rosin metal salt can be synthesized, for example, by reacting rosin with a metal compound by a known method.

The glass transition temperature (Tg) of the rosin metal salt is preferably 20 ℃ or higher, more preferably 50 ℃ or higher, further preferably 70 ℃ or higher, particularly preferably 80 ℃ or higher. The upper limit is not particularly limited, and may be 1000℃or less, or 800℃or less, or 700℃or less, for example. Within the above range, the tire performance such as wet grip performance tends to be more favorably obtained.

In the rubber composition, the content of the rosin metal salt is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The rubber composition may contain a plasticizer other than the rosin compound.

In the present specification, the plasticizer means a material imparting plasticity to the rubber component, and may be liquid at ordinary temperature (25 ℃) or may be solid. These may be used alone, or 2 or more kinds may be used in combination.

Examples of the plasticizer include oils, liquid polymers, resins, and the like. These may be used alone, or 2 or more kinds may be used in combination.

The oil is not particularly limited, and conventionally known oils such as paraffinic processing oil, aromatic processing oil, naphthenic processing oil and the like, low PCA (polycyclic aromatic) processing oil such as TDAE and MES, vegetable-derived oil, and mixtures thereof can be used. These may be used alone, or 2 or more kinds may be used in combination. From the viewpoint of life cycle analysis, lubricating oil, waste edible oil, and the like after use in a rubber mixing mixer, an automobile engine, and the like can be suitably used.

Examples of the plant-derived oil (also referred to as vegetable oil) include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower seed oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, and the like.

As a result of the presence of the oil, examples of the product include products of Kaisha, sanyo oil chemical Co., ltd., japanese energy Co., ltd., olisoy, H & R, feng nations oil Co., showa Shell oil Co., ltd., fuji Co., and Niqing Oriyou group Co., ltd.

Examples of the liquid polymer include a liquid diene polymer (liquid rubber) and a liquid farnesene polymer at 25 ℃. The liquid rubber may be: liquid styrene butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene isoprene copolymer (liquid SIR), liquid styrene butadiene styrene block copolymer (liquid SBS block polymer), liquid styrene isoprene styrene block copolymer (liquid SIS block polymer), and the like. Their terminal, backbone chains may be modified with polar groups. In addition, their hydrides may also be used.

The weight average molecular weight (Mw) of the liquid diene polymer in terms of polystyrene as measured by Gel Permeation Chromatography (GPC) is preferably 1.0×10 ³～5.0×10⁴, more preferably 3.0×10 ³～1.5×10⁴. The lower limit or the upper limit of the Mw of the liquid diene polymer may be 4500 or 8500.

In the present specification, the Mw of the liquid diene polymer is a polystyrene equivalent measured by Gel Permeation Chromatography (GPC).

Examples of the liquid diene polymer include products of Sartomer company, kuraray, etc.

As the resin, a resin (resin) which is generally used may be used as the tire compound, and may be liquid or may be solid at ordinary temperature (25 ℃). Examples thereof include aromatic vinyl polymers (aromatic vinyl polymer), coumarone-indene resins, coumarone resins, indene resins, phenol resins, petroleum resins, terpene resins, and acrylic resins. In addition, the resin may be a hydrogenated resin (hydrogenated resin). These may be used alone, or 2 or more kinds may be used in combination. The resin itself may be a resin obtained by copolymerizing monomer components of various sources. Among them, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins thereof are preferable.

When a resin that is solid at ordinary temperature is used, the softening point of the resin is preferably 50 ℃ or higher, more preferably 55 ℃ or higher, still more preferably 60 ℃ or higher, and particularly preferably 85 ℃ or higher. The temperature is preferably 160℃or lower, more preferably 150℃or lower, further preferably 140℃or lower, and particularly preferably 100℃or lower. When the amount is within the above range, the effect tends to be more effectively obtained.

When the resin is liquid at ordinary temperature, the softening point of the resin is preferably 20 ℃ or less, more preferably 10 ℃ or less, and still more preferably 0 ℃ or less.

The hydrogenated resin is also preferably the same as the above softening point.

The softening point of the resin was measured by a ring and ball softening point measuring device according to JIS K6220-1:2001, and a temperature at which the ball drops.

The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, a resin obtained by polymerizing α -methylstyrene and/or styrene may be exemplified, and specifically, a homopolymer of styrene (styrene resin), a homopolymer of α -methylstyrene (α -methylstyrene resin), a copolymer of α -methylstyrene and styrene, a copolymer of styrene and other monomers, and the like may be exemplified.

The coumarone-indene resin is a resin containing coumarone and indene as main monomer components constituting a skeleton (main chain) of the resin. Examples of the monomer component contained in the skeleton other than coumarone and indene include styrene, α -methylstyrene, methylindene, and vinyltoluene.

The coumarone resin is a resin containing coumarone as a main monomer component constituting a skeleton (main chain) of the resin.

The indene resin is a resin containing indene as a main monomer component constituting a skeleton (main chain) of the resin.

As the phenol resin, for example, a known phenol resin such as a polymer obtained by reacting phenols with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or base catalyst can be used. Among them, a phenol resin (novolak type phenol resin or the like) obtained by a reaction with an acid catalyst is preferable.

Examples of the petroleum resin include C5-based resins, C9-based resins, C5/C9-based resins, dicyclopentadiene (DCPD) resins, C9/DCPD resins, and hydrides thereof. Among them, preferred are DCPD resins, hydrogenated DCPD resins, C9/hydrogenated DCPD resins.

The terpene resin is a polymer containing a terpene as a constituent unit, and examples thereof include a polyterpene resin obtained by polymerizing a terpene compound, an aromatic modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, and the like. As the aromatic modified terpene resin, a terpene phenol resin using a terpene compound and a phenol compound as raw materials, a terpene styrene resin using a terpene compound and a styrene compound as raw materials, and a terpene phenol styrene resin using a terpene compound, a phenol compound and a styrene compound as raw materials can also be used. The terpene compound may be α -pinene, β -pinene, or the like, the phenol compound may be phenol, bisphenol a, or the like, and the aromatic compound may be a styrene compound (styrene, α -methylstyrene, or the like). Among them, aromatic modified terpene resins are preferable.

The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene acrylic resin such as a styrene acrylate resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, and the like are mentioned. Among them, a solvent-free type carboxyl group-containing styrene acrylic resin is preferably used.

Examples of the resin include products such as Wash petrochemicals, sumitomo bakelite, anono chemicals, tosoh, rutgersChemicals, BASF, arizona Chemical, exxon Mobil, KRATON, nikkon chemicals, japanese catalyst, ENEOS, sichuan Chemical, and Takava Chemical.

As the plasticizer, from the viewpoint of sustainability, the plant-derived plasticizers such as the above-mentioned plant-derived oils and farnesene-based polymers are preferably used.

The farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a constituent unit based on farnesene. Among the farnesenes, there are isomers of α -farnesene ((3E, 7E) -3,7, 11-trimethyl-1, 3,6, 10-dodecatetraene), β -farnesene (7, 11-dimethyl-3-methylene-1, 6, 10-dodecatriene) and the like, and (E) - β -farnesene having the following structure is preferable.

[ Chemical formula 1]

The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer), or may be a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone, or 2 or more kinds may be used in combination. Among them, a copolymer of farnesene and a vinyl monomer is preferable.

Examples of the vinyl monomer include: and conjugated diene compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α -methylstyrene, 2, 4-dimethylstyrene, 2, 4-diisopropylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyl dimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N-dimethylaminoethyl styrene, N-dimethylaminomethyl styrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-tert-butylstyrene, 3-tert-butylstyrene, 4-tert-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene and tertiary amino group-containing diphenylethylene, and butadiene and isoprene. They may be used singly of 1 kind, or may be used in combination of 2 or more kinds. Among them, butadiene is preferable. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferable.

In the farnesene-vinyl monomer copolymer, the mass-based copolymerization ratio of the farnesene and the vinyl monomer (farnesene/vinyl monomer) is preferably 40/60 to 90/10.

The farnesene polymer may preferably have a weight average molecular weight (Mw) of 3000 or more and 30 ten thousand or less. The Mw of the farnesene-based polymer is preferably 8000 or more, more preferably 10000 or more, and further preferably 10 ten thousand or less, more preferably 6 ten thousand or less, and further preferably 5 ten thousand or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The farnesene-based polymer may be in either a liquid state or a solid state at ordinary temperature (25 ℃). Among them, a liquid farnesene polymer which is in a liquid state at ordinary temperature (25 ℃) is preferable.

In the rubber composition, the content of the plasticizer (the total amount of the rosin compound and the plasticizer other than the rosin compound) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, further preferably 25 parts by mass or more, further preferably 35 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and still more preferably 45 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The plasticizer content includes the amounts of oil and resin contained in the oil-extended rubber and the resin-filled rubber.

In the rubber composition, the content of the solid plasticizer in a solid state at normal temperature (25 ℃) is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The content of the resin in a solid state at normal temperature (25 ℃) is also preferably in the same range.

In the rubber composition, the content of the liquid plasticizer in a liquid state at normal temperature (25 ℃) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more, relative to 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and still more preferably 20 parts by mass or less. When the amount is within the above range, the effect tends to be more effectively obtained.

The content of the liquid plasticizer includes the amount of oil contained in the oil-filled rubber and the amount of liquid resin of the resin-filled rubber filled with the liquid resin.

The content of the oil in a liquid state at ordinary temperature (25 ℃) is also preferably in the same range.

The rubber composition preferably contains an anti-aging agent from the viewpoints of crack resistance, ozone resistance, etc.

The antioxidant is not particularly limited, and examples thereof include: naphthylamine antioxidants such as phenyl- α -naphthylamine; diphenylamine antioxidants such as octylated diphenylamine and 4,4 '-bis (α, α' -dimethylbenzyl) diphenylamine; p-phenylenediamine antioxidants such as N-isopropyl-N ' -phenyl-p-phenylenediamine, N- (1, 3-dimethylbutyl) -N ' -phenyl-p-phenylenediamine, and N, N ' -di-2-naphthyl-p-phenylenediamine; quinoline antioxidants such as polymers of 2, 4-trimethyl-1, 2-dihydroquinoline; monophenol-based antioxidants such as 2, 6-di-t-butyl-4-methylphenol and styrenated phenol; bisphenol-based, triphenol-based, polyphenol-based antioxidants such as tetrakis- [ methylene-3- (3 ',5' -di-t-butyl-4 ' -hydroxyphenyl) propionate ] methane. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and polymers of N- (1, 3-dimethylbutyl) -N' -phenyl-p-phenylenediamine and 2, 4-trimethyl-1, 2-dihydroquinoline are more preferable. Examples of the commercial products include products of Seikovia chemical Co., ltd., sumitomo chemical Co., ltd., dain chemical industry Co., ltd., fulex (Flexsys) and the like.

In the rubber composition, the content of the antioxidant is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 4.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less.

The rubber composition preferably contains stearic acid.

In the rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and further preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones may be used, and for example, products such as daily oil corporation, king corporation, fuji film, photo-pure chemical corporation, kiloleaf fatty acid corporation, and the like may be used.

The rubber composition preferably contains zinc oxide.

In the rubber composition, the zinc oxide content is preferably 0.5 parts by mass or more, more preferably 1.7 parts by mass or more, and further preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, based on 100 parts by mass of the rubber component.

As the Zinc oxide, conventionally known Zinc oxide may be used, and for example, products such as Sanwell metal mining Co., toho Zinc Co., ltd., white water technology (Hakusui Tech), chemical industry Co., ltd., and the like may be used.

Waxes may be compounded in the rubber composition.

In the rubber composition, the content of the wax is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and further preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, based on 100 parts by mass of the rubber component.

The wax is not particularly limited, and petroleum waxes, natural waxes, and the like may be mentioned, and synthetic waxes obtained by refining or chemically treating various waxes may be used. These waxes may be used alone or in combination of 2 or more.

Examples of the petroleum wax include paraffin wax and microcrystalline wax. The natural wax is not particularly limited as long as it is derived from petroleum external resources, and examples thereof include plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; animal waxes such as beeswax, lanolin and spermaceti; mineral waxes such as ceresin (ozokerite), ceresin (ceresine), and petrolatum (petrolatum); and refined products thereof. As the commercial products, for example, products of Dain chemical industry Co., ltd., japan refined wax Co., ltd., seikovia chemical Co., ltd., etc. can be used.

Among the above rubber compositions, sulfur is preferably compounded from the viewpoint of forming a moderate crosslinking chain on the polymer chain and imparting good performance.

In the rubber composition, the sulfur content is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and still more preferably 1.0 part by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and still more preferably 2.0 parts by mass or less.

Examples of sulfur include powdery sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, which are generally used in the rubber industry. As a commercial product, it is possible to obtain, can use Crane chemical industry Co., ltd., light well sulfur Co., ltd., four kingdoms chemical industry Co., ltd., fulexes (Flexsys), japan Games Co., ltd products of Fine well chemical industries, inc. They may be used alone, or 2 or more kinds may be used in combination.

The rubber composition preferably contains a vulcanization accelerator.

The content of the vulcanization accelerator in the rubber composition is not particularly limited, and may be freely determined according to the desired vulcanization rate and crosslinking density, and is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and further preferably 4.4 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and still more preferably 6.0 parts by mass or less.

The type of the vulcanization accelerator is not particularly limited, and a commonly used vulcanization accelerator can be used. Examples of the vulcanization accelerator include: thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N); sulfenamide vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxyethylidene-2-benzothiazole sulfenamide, and N, N' -diisopropyl-2-benzothiazole sulfenamide; guanidine vulcanization accelerators such as diphenylguanidine, di-o-tolylguanidine and o-tolylguanidine. As the commercial products, products such as Sumitomo chemical Co., ltd and Dain chemical industry Co., ltd can be used. They may be used alone, or 2 or more kinds may be used in combination. Among them, sulfenamide-based, guanidine-based and benzothiazole-based vulcanization accelerators are preferable.

In addition to the above components, the rubber composition may be appropriately compounded with compounding agents commonly used in the tire industry, for example, materials such as a mold release agent.

The rubber composition can be produced, for example, by the following method or the like: and a method in which the above components are kneaded and vulcanized using a rubber kneading apparatus such as an open roll or a Banbury mixer.

In the basic kneading step of kneading additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator, the kneading temperature is preferably 100 ℃ or higher, more preferably 120 ℃ or higher, and further preferably 180 ℃ or lower, more preferably 170 ℃ or lower. In the final kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is preferably 70℃or higher, more preferably 80℃or higher, and further preferably 120℃or lower, more preferably 110℃or lower. The composition kneaded with the vulcanizing agent and the vulcanization accelerator may be subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is preferably 140℃or higher, more preferably 150℃or higher, and further preferably 190℃or lower, more preferably 185℃or lower.

The rubber composition can be used for tires, soles, flooring materials, vibration-proof materials, butyl frame materials, belts, hoses, gaskets, studs, other rubber-made industrial products, and the like. In particular, the rubber composition is preferably used as a rubber composition for a tire in view of excellent tire performance such as wet grip performance.

The tire component to which the rubber composition is applied is not particularly limited, and examples thereof include any component of a tire such as a tread running surface (cap tread), a sidewall, a base tread (base tread), a bead apex, an inner liner, a base tread (under tread), a cushion layer coating (breaker topping), a ply coating (ply topping), and the like. Among them, the use for a tread running surface is preferable from the viewpoint of excellent wet grip performance and the like.

< Tire >

The rubber composition may be preferably used for a tire. The tire may be a pneumatic tire, a non-pneumatic tire, or the like, and among them, a pneumatic tire is preferable. In particular, the tire can be preferably used as a summer tire (summer tire), a winter tire (studless tire, snowfield tire, studded tire, etc.), a full season tire, etc. The tire can be used as a tire for a passenger car, a tire for a large SUV, a tire for a heavy load such as a truck or a passenger car, a tire for a pickup truck, a tire for a two-wheeled vehicle, a tire for racing (high performance tire), or the like. Among them, the present invention can be preferably used for tires for passenger cars and tires for pickup trucks.

The tire may be manufactured by a conventional method using the rubber composition. For example, a tire may be manufactured by: the rubber composition blended with various materials is extruded into the shape of a tire member such as a tread running surface at an unvulcanized stage, and is molded by a conventional method on a tire molding machine together with other tire members to form an unvulcanized tire, and then the unvulcanized tire is heated and pressurized in a vulcanizing machine to manufacture a tire.

Examples (example)

Hereinafter, examples (examples) considered preferable in the implementation are shown, but the scope of the present invention is not limited to the examples.

(Synthesis of modified resin A (sodium abietate))

Gum rosin was added to 10 mass% NaOH and stirred at 90 to 95 ℃ for 3 hours. Then, the water was removed to obtain a modified resin a (gum rosin Na).

(Synthesis of modified resin B (sodium abietate))

The polymerized rosin was added to 10 mass% NaOH and stirred at 90 to 95 ℃ for 3 hours. Then, the water was removed to obtain a modified resin B (polymerized rosin Na).

(Synthesis of modified resin C (Zinc rosin acid))

To an aqueous solution of gum rosin Na produced by the synthesis of the modified resin a, an aqueous solution of ZnSO ₄ was added, and the precipitate was dried to obtain a modified resin C (gum rosin Zn).

The materials used for the synthesis of the modified resins a to C are as follows. The glass transition temperature (Tg) of the rosin compound was measured by the following method.

Gum rosin: fuji film and Guangdong Kagaku Co., ltd. (Tg: 40 ℃ C.)

Polymerized rosin: synthomer company (Tg: 90 ℃ C.)

NaOH: fuji film and light purity chemical Co., ltd

ZnSO ₄: fuji film and light purity chemical Co., ltd

< Glass transition temperature (Tg) >)

The Tg of the rosin compound was measured at a temperature rise rate of 10℃per minute by using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan according to JIS K7121-1987, and the glass transition onset temperature was obtained.

Fig. 1 shows IR spectra of gum rosin, modified resin a (gum rosin Na), and modified resin C (gum rosin Zn) in the synthesis of modified resin A, C. From the IR spectrum, gum rosin Na and gum rosin Zn have been synthesized.

Hereinafter, various chemicals used in the manufacture of tires will be described in summary. The chemicals were purified according to a predetermined method as needed.

NR: SVR-L of Nonomuria trade Co

SBR: HPR840 (modified SBR, styrene content: 10% by mass, vinyl bond content: 41% by mass) manufactured by JSR Co., ltd.)

BR: BR730 manufactured by JSR Co., ltd

Carbon black: diablack I (N220, N ₂SA：114m²/g) manufactured by Mitsubishi chemical corporation

Silica: ultrasil VN3 (N ₂SA：175m²/g) manufactured by Evonik Degussa corporation

Silane coupling agent: si266 (bis (3-triethoxysilylpropyl) disulfide manufactured by Yingchuang (EVONIK) Co., ltd.)

Oil: diana Process NH-70S (aromatic processing oil) manufactured by Ningxing Co., ltd

Aromatic vinyl polymer: SYLVARES SA 85 (copolymer of alpha-methylstyrene and styrene, softening point: 85 ℃ C.) manufactured by Arizona chemical Co., ltd

Resin: gum rosin manufactured by Fuji film and Guangdong Kagaku Co., ltd. (Tg: 40 ℃ C.)

Modified resin A: the modified resin A (sodium abietate)

Modified resin B: the modified resin B (sodium abietate)

Modified resin C: the modified resin C (zinc rosin)

Zinc oxide: zinc white No. 1 manufactured by Mitsui metal mining Co., ltd

Wax: OZOACE 0355,035,55 manufactured by japan refined wax Co., ltd

Anti-aging agent 1: NOCRAC 6C (N- (1, 3-dimethylbutyl) -N' -phenyl-p-phenylenediamine, manufactured by Dai Nei Xin Chemie Co Ltd.)

Anti-aging agent 2: NOCRAC RD (Poly (2, 4-trimethyl-1, 2-dihydroquinoline) manufactured by Dai Xin Chemie Co Ltd

Stearic acid: stearic acid "Ailanthus (Tsukii)" manufactured by Nikko corporation "

Sulfur: powdered sulfur (containing 5% oil) manufactured by Crane Chemie Co., ltd

Vulcanization accelerator 1: NOCCELER D (diphenylguanidine) manufactured by Dain New chemical industry Co., ltd

Vulcanization accelerator 2: NOCCELER CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Dain New chemical industry Co., ltd

< Production of test tire >

Materials other than sulfur and a vulcanization accelerator were kneaded according to the formulation shown in table 1 to obtain kneaded materials.

Sulfur and a vulcanization accelerator were added to the kneaded materials according to the formulation shown in table 1, and the mixture was kneaded at 70 ℃ for 8 minutes to obtain unvulcanized rubber compositions.

The unvulcanized rubber composition was extruded into a tread running surface shape, and then bonded together with other tire components on a tire molding machine to form an unvulcanized tire, which was press-vulcanized at 170℃for 20 minutes to obtain a test tire (size 195/65R15, specification: table 1).

The results calculated based on the following evaluation methods are shown in table 1, assuming that the test tires were obtained from the rubber compositions having the changed formulations and specifications according to table 1.

The reference comparison is set as follows, for example.

Reference comparative example: comparative example 1

< Viscoelastic test >

Viscoelasticity measurement samples having a length of 40mm×a width of 3mm×a thickness of 0.5mm were collected so as to extend from the inside of the rubber layer of the tread running surface of each test tire to the tire circumferential direction, and tan δ and E were measured at a temperature of 30 ℃, an initial strain of 10%, a dynamic strain of 2%, a frequency of 10Hz, a tensile mode, and a measurement time of 10 minutes using the RSA series manufactured by TA Instruments, to obtain measurement values 10 minutes after the start of the measurement. The thickness direction of the sample was taken as the tire radial direction.

< E and tan delta at drying >

The above-mentioned viscoelasticity measurement sample (length 40 mm. Times. Width 3 mm. Times. Thickness 0.5 mm) was dried until the weight became constant under the conditions of normal temperature and normal pressure, to obtain a vulcanized rubber composition at the time of drying. The complex elastic modulus E and loss tangent tan δ of the vulcanized rubber composition (rubber sheet) at the time of drying were measured as E and tan δ at the time of drying by the above-mentioned method.

< E and tan delta upon Water wetting >

The above viscoelasticity measurement sample (length 40 mm. Times. Width 3 mm. Times. Thickness 0.5 mm) was immersed in 100ml of water at 23℃for 2 hours to obtain a vulcanized rubber composition upon wetting with water. The viscoelasticity was measured in water by the method described above using an RSA dip-measuring jig, and the complex elastic modulus E and loss tangent tan δ of the vulcanized rubber composition (rubber sheet) in water-wet state were used as E and tan δ in water-wet state. The water temperature was set to 30 ℃.

< Wet grip Property >

Each test tire was mounted on all wheels of a vehicle (FF 2000cc, japan) so as to travel 10 turns on a wet road route, and 20 test drivers evaluated the braking performance in the wet road area at this time on 5-point scales of 1-5 points. The greater the score, the more excellent the performance. The total score of the scores of 20 persons was calculated, and the total score of the reference comparative examples was set to 100, and the index was made. The larger the index, the more excellent the wet grip performance.

TABLE 1

The present invention (1) is a rubber composition comprising a rubber component, a filler and a rosin compound, and satisfying the following formulas (1) to (2).

(1) Tan delta on water wetting/tan delta on drying >1.00

(2) E on wetting/E on drying <1.00

The invention (2) is the rubber composition according to the invention (1), wherein the filler content Fc (parts by mass) satisfies the following formula with respect to 100 parts by mass of the rubber component.

40<Fc<90

The invention (3) is the rubber composition according to the invention (1) or (2), wherein the rosin compound contains a rosin metal salt.

The invention (4) is the rubber composition of any combination of the invention (1) to (3), wherein the rosin compound is selected from at least 1 of sodium rosin acid and zinc rosin acid.

The present invention (5) is the rubber composition according to any combination of the present invention (1) to (4), wherein the rubber component contains at least 1 of a natural rubber, a butadiene rubber, and a styrene butadiene rubber.

The invention (6) is the rubber composition according to any combination of the invention (1) to (5), wherein the content of the natural rubber is 30 to 70 mass% in 100 mass% of the rubber component.

The invention (7) is the rubber composition according to any combination of the invention (1) to (6), wherein the content of butadiene rubber in 100 mass% of the rubber component is 5 to 50 mass%.

The invention (8) is the rubber composition according to any combination of the invention (1) to (7), wherein the content of the styrene butadiene rubber in 100 mass% of the rubber component is 20 to 80 mass%.

The invention (9) is the rubber composition according to any combination of the invention (5) to (8), wherein the styrene butadiene rubber has a styrene content of 5 to 50 mass%.

The invention (10) is the rubber composition according to any combination of the invention (5) to (9), wherein the vinyl bond amount of the styrene butadiene rubber is 10 to 70 mass%.

The present invention (11) is the rubber composition according to any one of the combinations of the present invention (1) to (10), wherein the filler contains carbon black having an N ₂ SA of 50 to 150m ²/g.

The invention (12) is the rubber composition according to any combination of the invention (1) to (11), wherein the content of carbon black is 1 to 50 parts by mass based on 100 parts by mass of the rubber component.

The invention (13) is the rubber composition according to any combination of the invention (1) to (12), wherein the silica content is 40 to 80 parts by mass based on 100 parts by mass of the rubber component.

The invention (14) is the rubber composition according to any one of the combinations of the invention (1) to (13), wherein the content of the rosin compound is 5 to 50 parts by mass based on 100 parts by mass of the rubber component.

The present invention (15) is the rubber composition according to any one of the combinations of the present invention (1) to (14), wherein the rubber composition satisfies the following formula, when the water-wet tan δ/dry tan δ is used as index 1 and the water-wet E/dry E is used as index 2.

Index 1/index 2>1.05

The invention (16) is the rubber composition according to the invention (15), wherein the rubber composition satisfies the following formula.

Index 1/index 2>1.10

The invention (17) is the rubber composition according to any combination of the invention (1) to (16), wherein the rubber composition satisfies the following formula.

Tan delta on water wetting/tan delta on drying >1.07

The present invention (18) is the rubber composition according to any combination of the present invention (1) to (17), wherein the rubber composition satisfies the following formula.

E on wetting/E on drying <0.97

The present invention (19) is a tire having a tread surface comprising the rubber composition according to any one of the combinations of the present invention (1) to (18).

Claims

1. A rubber composition comprising a rubber component, a filler and a rosin compound, wherein the following formulas (1) to (2) are satisfied:

(1) Tan delta when wet/tan delta when dry >1.00,

(2) E when wet/E when dry <1.00,

In the formulas (1) and (2), tan δ and E are loss tangent and complex elastic modulus measured under conditions of 30 ℃ temperature, 10% initial strain, 1% dynamic strain, 10Hz frequency, and stretching mode.

2. The rubber composition according to claim 1, wherein the filler content Fc satisfies the following formula with respect to 100 parts by mass of the rubber component:

40<Fc<90，

The unit of Fc is parts by mass.

3. The rubber composition according to claim 1 or 2, wherein the rosin compound contains a rosin metal salt.

4. The rubber composition according to claim 1 or 2, wherein the rosin compound is selected from at least 1 of sodium abietate and zinc abietate.

5. The rubber composition according to claim 1 or 2, wherein the rubber component contains at least 1 of a natural rubber, a butadiene rubber, and a styrene butadiene rubber.

6. The rubber composition according to claim 1 or 2, wherein the content of the natural rubber is 30 to 70 mass% in 100 mass% of the rubber component.

7. The rubber composition according to claim 1 or 2, wherein the content of butadiene rubber is 5 to 50 mass% in 100 mass% of the rubber component.

8. The rubber composition according to claim 1 or 2, wherein the content of the styrene butadiene rubber is 20 to 80 mass% in 100 mass% of the rubber component.

9. The rubber composition according to claim 5, wherein the styrene butadiene rubber has a styrene content of 5 to 50 mass%.

10. The rubber composition according to claim 5, wherein the vinyl bond content of the styrene butadiene rubber is 10 to 70 mass%.

11. The rubber composition according to claim 1 or 2, wherein the filler contains carbon black having an N ₂ SA of 50 to 150m ²/g.

12. The rubber composition according to claim 1 or 2, wherein the content of carbon black is 1 to 50 parts by mass relative to 100 parts by mass of the rubber component.

13. The rubber composition according to claim 1 or 2, wherein the content of silica is 40 to 80 parts by mass relative to 100 parts by mass of the rubber component.

14. The rubber composition according to claim 1 or 2, wherein the content of the rosin compound is 5 to 50 parts by mass relative to 100 parts by mass of the rubber component.

15. The rubber composition according to claim 1 or 2, wherein the rubber composition satisfies the following formula when taking tan δ at the time of water wetting/tan δ at the time of drying as index 1 and taking E at the time of water wetting/E at the time of drying as index 2:

index 1/index 2>1.05.

16. The rubber composition of claim 15, wherein the rubber composition satisfies the following formula:

Index 1/index 2>1.10.

17. The rubber composition according to claim 1 or 2, wherein the rubber composition satisfies the following formula:

Tan delta when wet/tan delta when dry >1.07.

18. The rubber composition according to claim 1 or 2, wherein the rubber composition satisfies the following formula:

E when wet/E when dry <0.97.

19. A tire comprising a tread surface comprising the rubber composition according to claim 1 or 2.