JP7424090B2 - Rubber composition for tires - Google Patents

Description

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

Spiked tires have been used or chains have been attached to the tires for driving on icy and snowy roads, but this causes environmental problems such as dust, so studless tires have been proposed as an alternative. Studless tires are used on snowy and icy roads, where the road surface is more uneven than on regular roads, so improvements have been made in terms of materials and design. In order to enhance the softening effect, rubber compositions containing a large amount of softener have been developed (see Patent Document 1, etc.).

For example, increasing the amount of butadiene rubber may be considered as a means to improve the on-ice performance of studless tires, but increasing the amount too much will increase the mobility in the rubber and cause blooming of various chemicals, so increasing the amount of butadiene rubber is not recommended. There are limits. Furthermore, when the amount of butadiene rubber is increased, the natural rubber ratio decreases, resulting in a problem that the strength of the rubber is insufficient and the abrasion resistance deteriorates.

Other methods have been proposed, including a method of adding fillers such as zinc oxide whiskers (see Patent Document 2) and a method of adding short fibers (see Patent Document 3), but there are concerns that they may reduce wear resistance. However, it is not a sufficient method to improve on-ice performance, and there is still room for improvement. Thus, further improvements are desired in achieving both on-ice performance and abrasion resistance while suppressing chemical blooming.

JP2009-091482A Japanese Patent Application Publication No. 2005-53977 Japanese Patent Application Publication No. 2002-249619

The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a rubber composition for a tire that can improve the overall performance of on-ice performance and wear resistance, and a tire using the same.

The present invention relates to a rubber composition for a tire, which includes a rubber component containing an isoprene rubber and a conjugated diene polymer, and water-soluble particles, the water-soluble particles satisfying the following formula (I).
D50≦30 (I)
(D50 in formula (I) represents the median particle size (μm) of water-soluble particles.)

The water-soluble particles preferably satisfy the following formula (II).
A/D50≧0.5 (II)
(A in formula (II) represents the content (parts by mass) of water-soluble particles with respect to 100 parts by mass of the rubber component. D50 represents the median particle size (μm) of the water-soluble particles.)

The content of the water-soluble particles relative to 100 parts by mass of the rubber component is preferably 10 parts by mass or more, more preferably 25 parts by mass or more.

The content of isoprene rubber in 100% by mass of the above rubber component is 20% by mass or more, the content of conjugated diene polymer is 20% by mass or more, and silica in 100% by mass of the total content of silica and carbon black. It is preferable that the content is 50% by mass or more.

The content of the liquid plasticizer relative to 100 parts by mass of the rubber component is preferably 30 parts by mass or less.

The conjugated diene polymer preferably includes a conjugated diene polymer having a cis content of 90% by mass or more.

The median particle size of the water-soluble particles is preferably 10 μm or more.

It is also preferable that the rubber component further contains styrene-butadiene rubber, and the content of the styrene-butadiene rubber in 100 parts by mass of the rubber component is greater than or equal to the content of the water-soluble particles in 100 parts by mass of the rubber component.

The rubber composition further contains particulate silica having a nitrogen adsorption specific surface area of 180 m ² /g or more, and the content of the particulate silica with respect to 100 parts by mass of the rubber component is not less than the content of water-soluble particles with respect to 100 parts by mass of the rubber component. It is also preferable.

It is also preferable that the rubber composition further contains a resin, and the content of the resin with respect to 100 parts by mass of the rubber component is equal to or greater than the content of the water-soluble particles with respect to 100 parts by mass of the rubber component.

The rubber composition further includes a resin, and the resin is preferably at least one selected from the group consisting of terpene resins, C5 resins, and C9 resins.

The present invention also relates to a tire having a member made using the rubber composition.

Preferably, the tire is a winter tire.

Preferably, the member is a tread.

It is also preferable that the maximum thickness of the tread is 5.5 mm or more.

The present invention is a tire rubber composition comprising a rubber component containing an isoprene rubber and a conjugated diene polymer, and water-soluble particles, where the water-soluble particles satisfy the following formula (I). The overall performance of on-ice performance and wear resistance can be improved.
D50≦30 (I)
(D50 in formula (I) represents the median particle size (μm) of water-soluble particles.)

FIG. 1 is a sectional view showing the vicinity of the tread of a tire.

The tire rubber composition of the present invention includes a rubber component containing an isoprene rubber and a conjugated diene polymer, and water-soluble particles, and the median particle size of the water-soluble particles satisfies a predetermined relationship. The rubber composition can improve the overall performance of on-ice performance and abrasion resistance.

Although the reason why such effects are obtained is not clear, it is presumed as follows.
Studless tires are required to have grip performance on ice, but in order to achieve this performance, water-soluble particles are added to the mix.The water-soluble particles dissolve with moisture on the road surface, creating voids, which reduce the edge effect. obtained, and the water film can also be removed. Furthermore, by using water-soluble particles with a median particle size below a predetermined value, the amount of edges in the voids formed by dissolving the water-soluble particles increases, resulting in a greater edge effect and water film removal effect. This results in excellent on-ice performance. Furthermore, when the median particle size of the water-soluble particles is less than a predetermined value, the water-soluble particles are less likely to become a starting point of fracture, and the amount of decrease in wear resistance is reduced. As a result, it is presumed that not only excellent on-ice performance can be achieved, but also good abrasion resistance can be obtained, and the overall performance of on-ice performance and abrasion resistance can be improved.

Furthermore, as another effect, since water-soluble particles react with moisture, they can suppress the adhesion of water to the metal cord inside the tire. When used, the smaller particle size has a larger specific surface area as a whole, so the suppressing effect can be increased.

(rubber component)
The rubber composition includes a rubber component containing an isoprene-based rubber and a conjugated diene-based polymer.
Isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. The NR can be SIR20, RSS#3, TSR20, etc., and the IR can be IR2200, which are common in the tire industry. Modified NR includes deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., modified IR Examples include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

The content of isoprene rubber in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more from the viewpoint of overall performance of on-ice performance and abrasion resistance. The upper limit of the content is not particularly limited, but is preferably 80% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less.

The conjugated diene polymer is selected from the group consisting of, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and myrcene. Polymers having repeating units derived from at least one monomer can be used. In particular, a polymer having a repeating unit derived from at least one monomer selected from the group consisting of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene can be suitably used. That is, the conjugated diene compound constituting the conjugated diene polymer is at least one conjugated diene compound selected from the group consisting of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene. It is also one of the preferred embodiments. Among these, it is particularly preferable that the conjugated diene polymer is butadiene rubber (BR).

BR is not particularly limited, and includes, for example, BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (BR containing SPB), butadiene rubber synthesized using a rare earth catalyst (rare earth BR) and tin-modified butadiene rubber modified with a tin compound (tin-modified BR), which are common in the tire industry. As a commercially available BR, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used. These may be used alone or in combination of two or more.

The cis content of the conjugated diene polymer is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more. This provides better on-ice performance. Thus, it is particularly preferable that the conjugated diene polymer contains a conjugated diene polymer with a cis content of 90% by mass or more, for example, the conjugated diene polymer has a cis content of 90% by mass. An example of a suitable form includes the above conjugated diene polymer and a conjugated diene polymer having a cis content of less than 90% by mass.
In this specification, the cis content (cis-1,4-bond amount) is a value calculated from the signal intensity measured by infrared absorption spectrum analysis or NMR analysis.

The content of the conjugated diene polymer in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass, from the viewpoint of overall performance on ice and abrasion resistance. % or more, more preferably 45% by mass or more. Further, the upper limit of the content is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less.

As the conjugated diene polymer, either an unmodified conjugated diene polymer or a modified conjugated diene polymer can be used.
As the modified conjugated diene polymer, a conjugated diene polymer having a functional group that interacts with a filler such as silica can be used. For example, a terminal-modified conjugated diene-based polymer in which at least one end of the conjugated diene-based polymer is modified with a compound (modifier) having the above-mentioned functional group (a terminal-modified conjugated diene-based polymer having the above-mentioned functional group at the end) ), main chain modified conjugated diene polymers having the above functional groups in the main chain, and main chain terminal modified conjugated diene polymers having the above functional groups in the main chain and terminals (for example, main chain modified conjugated diene polymers having the above functional groups in the main chain). A main chain terminal-modified conjugated diene polymer with at least one end modified with the above-mentioned modifying agent) or a polyfunctional compound having two or more epoxy groups in the molecule (coupling), and a hydroxyl group and terminal-modified conjugated diene polymers into which epoxy groups have been introduced.

Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, and disulfide groups. group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. . Note that these functional groups may have a substituent. Among these, an amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

For example, as the modified conjugated diene polymer, a conjugated diene polymer modified with a compound (modifier) represented by the following formula can be suitably used.

In the above formula, R ¹ , R ² and R ³ are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH) or a derivative thereof. . R ⁴ and R ⁵ are the same or different and represent a hydrogen atom or an alkyl group. R ⁴ and R ⁵ may be combined to form a ring structure together with the nitrogen atom. n represents an integer.

Among the modified conjugated diene polymers that have been modified with the compound (modifier) represented by the above formula, the polymer terminal (active end) of solution polymerized butadiene rubber has been modified with the compound represented by the above formula. BR etc. are preferably used.

An alkoxy group is suitable for R ¹ , R ² and R ³ (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Furthermore, when R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

Specific examples of the above modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltriethoxysilane, Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Among these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferred. These may be used alone or in combination of two or more.

As the modified conjugated diene polymer, modified conjugated diene polymers modified with the following compounds (modifiers) can also be suitably used. Examples of modifiers include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; two or more of diglycidylated bisphenol A, etc. Polyglycidyl ethers of aromatic compounds having phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylene diamine , diglycidylamino compounds such as tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane;

Amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidine carbonyl chloride, N,N-dimethylcarbamic acid chloride, N,N-diethylcarbamic acid chloride; 1 , 3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane and other epoxy group-containing silane compounds;

(trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3 -(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide sulfide group-containing silane compounds such as propoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, N,N,N',N' (Thio)benzophenone compounds having an amino group and/or substituted amino group such as -bis-(tetraethylamino)benzophenone; 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N, Benzaldehyde compounds having an amino group and/or substituted amino group such as N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl- N-substituted pyrrolidones such as 2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone ; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurirolactam, N-vinyl-ω-laurirolactam, N-methyl-β-propiolactam, N-phenyl - N-substituted lactams such as β-propiolactam;

N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5 -Triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenyl) Examples include amino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, and the like. Among these, a modified conjugated diene polymer modified with an alkoxysilane is preferred.
Note that modification with the above compound (modifier) can be carried out by a known method.

In the above rubber composition, the total content of isoprene rubber and conjugated diene polymer in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more. and may be 100% by mass. The higher the total content is, the better the low-temperature properties are, and the more the required on-ice performance tends to be exhibited.

The above-mentioned rubber composition may contain other rubber components within a range that does not impede the above-mentioned effects. Examples of other rubber components include diene rubbers such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). It will be done.

Among these, one preferable embodiment is for the rubber component to further include styrene-butadiene rubber (SBR).
The SBR is not particularly limited, and for example, those commonly used in the tire industry, such as emulsion polymerization SBR (E-SBR) and solution polymerization SBR (S-SBR), can be used. These may be used alone or in combination of two or more.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

Further, the SBR may be non-denatured SBR or modified SBR. Examples of the modified SBR include modified SBR into which functional groups similar to those of the modified conjugated diene polymer described above are introduced.

As the SBR, oil-extended SBR or non-oil-extended SBR may be used. When using oil-extended SBR, the amount of oil-extended SBR, that is, the content of oil-extended oil contained in SBR, is set to 100 parts by mass of the rubber solid content of SBR, because the effects of the present invention can be obtained more preferably. On the other hand, it is preferably 10 to 50 parts by mass.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more. The styrene content is preferably 60% by weight or less, more preferably 50% by weight or less, even more preferably 45% by weight or less, particularly preferably 40% by weight or less. When the styrene content is within the above range, the effects of the present invention can be more suitably achieved.
Note that in this specification, the styrene content of SBR is calculated by ¹ H-NMR measurement.

The vinyl content of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, because the effects of the present invention can be more suitably obtained. The vinyl content is preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 50 mol% or less.
In this specification, the vinyl content of SBR refers to the vinyl content of the butadiene moiety (the number of vinyl group units in the butadiene structure), and is calculated by ¹ H-NMR measurement.

The glass transition temperature (Tg) of SBR is preferably −90° C. or higher, more preferably −50° C. or higher because the effects of the present invention can be more suitably obtained. Further, the temperature is preferably 0°C or lower, more preferably -10°C or lower.
In this specification, the glass transition temperature is determined according to JIS-K7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan at a heating rate of 10°C/min. This is the measured value.

The weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more, even more preferably 300,000 or more, and particularly preferably 1,000,000 or more, because the effects of the present invention can be more suitably obtained. . Further, the Mw is preferably 2,000,000 or less, more preferably 1,800,000 or less.
In this specification, weight average molecular weight (Mw) refers to gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL manufactured by Tosoh Corporation). It can be determined by standard polystyrene conversion based on the measured value by SUPERMALTPORE HZ-M).

The content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, because the effects of the present invention can be more preferably obtained. be. Further, it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.
Furthermore, it is also preferable that the content of styrene-butadiene rubber in 100 parts by mass of the rubber component is equal to or higher than the content of water-soluble particles in 100 parts by mass of the rubber component, since the effects of the present invention can be obtained more preferably.

(water soluble particles)
The water-soluble particles are not particularly limited and can be used as long as they are soluble in water. For example, a material having a solubility in water at room temperature (20° C.) of 1 g/100 g water or more can be used. However, magnesium sulfate fibers with an average fiber length of 15 μm and an average fiber diameter of 0.5 μm are excluded.

The water-soluble particles satisfy the following formula (I). That is, the water-soluble particles have a median particle size of 30 μm or less. In other words, the water-soluble particles in the present invention are fine particles with a D50 of 30 μm or less.
D50≦30 (I)
(D50 in formula (I) represents the median particle size (μm) of water-soluble particles.)

When the above-mentioned water-soluble particles satisfy the above formula (I), by using such water-soluble particles, the amount of edges of the voids formed by dissolving the water-soluble particles increases, so that the edge effect and the removal of water film are reduced. The effect is greater and superior on-ice performance can be obtained. In addition, the water-soluble particles are less likely to become a starting point of fracture, and the amount of decrease in wear resistance is reduced. As a result, not only excellent on-ice performance can be achieved, but also good abrasion resistance can be obtained, and the overall performance of on-ice performance and abrasion resistance can be improved.

The median particle size (median diameter, D50) of the water-soluble particles is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of on-ice performance and wear resistance. On the other hand, the lower limit of the median particle size of the water-soluble particles is not particularly limited, but from the viewpoint of overall performance of on-ice performance and wear resistance, it is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and 10 μm or more. is particularly preferred.
In addition, in this specification, the median particle size is the particle size at 50% of the integrated mass value of the particle size distribution curve obtained by particle size distribution measurement using laser diffraction method, and specifically, in the examples described below. It can be measured by the method described.

The aspect ratio of the water-soluble particles is preferably 1:1 to 25, more preferably 1:1 to 20, even more preferably 1:1 to 15, and even more preferably 1:1 to 10 from the viewpoint of on-ice performance and abrasion resistance. is even more preferable, 1:1 to 5 is even more preferable, and 1:1 to 2.5 is particularly preferable.
Note that in this specification, the aspect ratio can be measured by observation using a transmission electron microscope.

The content of the water-soluble particles is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. Particularly preferably 25 parts by mass or more. By setting the content above the lower limit, the amount of components contributing to the edge effect increases, and good performance on ice tends to be obtained. The content is preferably 100 parts by weight or less, more preferably 70 parts by weight or less, still more preferably 50 parts by weight or less, particularly preferably 40 parts by weight or less, and most preferably 30 parts by weight or less. When the content is below the upper limit, good rubber physical properties such as breaking strength and abrasion resistance tend to be obtained.

The water-soluble particles preferably satisfy the following formula (II).
A/D50≧0.5 (II)
(A in formula (II) represents the content (parts by mass) of water-soluble particles with respect to 100 parts by mass of the rubber component. D50 represents the median particle size (μm) of the water-soluble particles.)

When the water-soluble particles satisfy the above formula (II), the overall performance of on-ice performance and abrasion resistance is significantly improved. A/D50 in the above formula (II) is more preferably 0.8 or more, even more preferably 1.5 or more, even more preferably 2.0 or more, and 2.5 or more. It is particularly preferable that On the other hand, the upper limit of A/D50 in the above formula (II) is not particularly limited, but from the viewpoint of overall performance of on-ice performance and wear resistance, it is preferably 10 or less, more preferably 5.0 or less, and 3.0 or less. is even more preferable.

Examples of the water-soluble particles include water-soluble inorganic salts and water-soluble organic substances. These may be used alone or in combination of two or more.

The water-soluble inorganic salts include metal sulfates such as magnesium sulfate and potassium sulfate; metal chlorides such as potassium chloride, sodium chloride, calcium chloride, and magnesium chloride; metal hydroxides such as potassium hydroxide and sodium hydroxide; Carbonates such as potassium carbonate and sodium carbonate; phosphates such as sodium hydrogen phosphate and sodium dihydrogen phosphate; and the like.

Examples of the water-soluble organic substances include lignin derivatives and saccharides.
As the lignin derivative, lignin sulfonic acid, lignin sulfonate, etc. are suitable. The lignin derivative may be obtained by either the sulfite pulp method or the kraft pulp method.

Examples of the ligninsulfonic acid salts include alkali metal salts, alkaline earth metal salts, ammonium salts, and alcohol amine salts of ligninsulfonic acid. Among these, alkali metal salts (potassium salt, sodium salt, etc.) and alkaline earth metal salts (calcium salt, magnesium salt, lithium salt, barium salt, etc.) of ligninsulfonic acid are preferred.

The lignin derivative preferably has a degree of sulfonation of 1.5 to 8.0/OCH ₃ . In this case, the lignin derivative contains lignin sulfonic acid and/or lignin sulfonate in which lignin and/or its decomposition product is substituted with a sulfo group (sulfone group), The sulfo group may be in an unionized state, or the hydrogen of the sulfo group may be substituted with an ion such as a metal ion. The degree of sulfonation is more preferably 3.0 to 6.0/OCH ₃ . By keeping it within the above range, good performance on ice tends to be obtained.

Note that the degree of sulfonation of the lignin derivative particles (the lignin derivative constituting the particles) is the introduction rate of sulfo groups, and is determined by the following formula.
Degree of sulfonation (/OCH ₃ )=
S (mol) in sulfone group in lignin derivative/methoxyl group (mol) in lignin derivative

The number of carbon atoms in the saccharide is not particularly limited and may be monosaccharide, oligosaccharide, or polysaccharide. Monosaccharides include tricarbon sugars such as aldotriose and ketotriose; tetracarbon sugars such as erythrose and threose; pentose sugars such as xylose and ribose; hexose sugars such as mannose, allose, altrose, and glucose; sedoheptulose, etc. Examples include seven carbon sugars. Examples of oligosaccharides include disaccharides such as sucrose and lactose; trisaccharides such as raffinose and melezitose; tetrasaccharides such as acarbose and stachyose; and oligosaccharides such as xylooligosaccharides and cellooligosaccharides. Examples of polysaccharides include glycogen, starch (amylose, amylopectin), cellulose, hemicellulose, dextrin, glucan, and the like.

Among these, magnesium sulfate is preferred as the water-soluble particles. By using magnesium sulfate with a median particle size below a predetermined value as the above-mentioned water-soluble particles, the amount of edges of the voids formed by melting of magnesium sulfate on the icy road surface increases, so the wiping effect becomes particularly large and the performance on ice becomes particularly noticeable. can be improved.

(silica)
The rubber composition preferably contains silica as a filler from the viewpoint of the overall performance. Examples of the silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and the like. Among these, wet process silica is preferred because it has a large number of silanol groups. As commercially available products, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The content of silica is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, particularly preferably It is 60 parts by mass or more. By setting it above the lower limit, good wear resistance tends to be obtained. The upper limit of the content is not particularly limited, but is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 170 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 80 parts by mass or less. be. By setting the amount below the upper limit, good dispersibility tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² /g or more, more preferably 140 m ² /g or more, even more preferably 160 m ² /g or more. There is a warning that good wear resistance and breaking strength can be obtained by setting the value above the lower limit. Further, the upper limit of N ₂ SA of silica is not particularly limited, but is preferably 500 m ² /g or less, more preferably 300 m ² /g or less, and still more preferably 250 m ² /g or less. By setting the amount below the upper limit, good dispersibility tends to be obtained.
Note that the N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

Further, it is also a preferable form to blend fine particle silica with a nitrogen adsorption specific surface area of 180 m ² /g or more as the silica.

The nitrogen adsorption specific surface area (N ₂ SA) of the particulate silica is 180 m ² /g or more, preferably 190 m ² /g or more, more preferably 200 m ² /g or more. By setting it above the lower limit, sufficient reinforcing properties and good wear resistance and fracture strength tend to be obtained. Further, the upper limit of N ₂ SA of the particulate silica is not particularly limited, but is preferably 500 m ² /g or less, more preferably 300 m ² /g or less. By setting the amount below the upper limit, good dispersibility tends to be obtained.
Note that the N ₂ SA of particulate silica is a value measured by the BET method according to ASTM D3037-93.

Examples of the particulate silica include dry process silica (anhydrous silica) and wet process silica (hydrated silica). Among these, wet process silica is preferred because it has a large number of silanol groups. As commercially available products, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The content of particulate silica is preferably 120 parts by mass or more, more preferably 125 parts by mass or more, still more preferably 130 parts by mass or more, based on 100 parts by mass of the rubber component. By setting it above the lower limit, good wear resistance and handling stability tend to be obtained. The upper limit of the content is not particularly limited, but is preferably 140 parts by mass or less, more preferably 135 parts by mass or less. By setting the amount below the upper limit, good dispersibility tends to be obtained.
Furthermore, since the effects of the present invention can be obtained more favorably, it is also preferable that the content of particulate silica with respect to 100 parts by mass of the rubber component is equal to or greater than the content of water-soluble particles with respect to 100 parts by mass of the rubber component.

In the above rubber composition, the silica content in 100% by mass of the total content of silica and carbon black is preferably 50% by mass or more, more preferably 80% by mass or more from the viewpoint of overall performance of on-ice performance and abrasion resistance. It is preferably 90% by mass or more, and more preferably 90% by mass or more.

(Silane coupling agent)
When the rubber composition contains silica, it is preferable that it further contains a silane coupling agent.
The silane coupling agent is not particularly limited, and examples thereof include 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-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide types such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto types such as NXT and NXT-Z manufactured by Momentive, vinyltriethoxysilane, and vinyl triethoxysilane. Vinyl type such as methoxysilane, amino type such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, glycidoxy such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc. Examples include nitro types such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro types such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, mercapto-based silane coupling agents are preferred. As commercially available products, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Kasei Kogyo Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, based on 100 parts by mass of silica. When it is above the lower limit, good breaking strength etc. tend to be obtained. Moreover, the said content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. When the content is below the upper limit, there is a tendency for effects commensurate with the amount blended to be obtained.

(Carbon black)
From the viewpoint of the overall performance, the rubber composition preferably contains carbon black as a filler. Examples of carbon black include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. Commercially available products include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kaya Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc. can. These may be used alone or in combination of two or more.

The content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more based on 100 parts by mass of the rubber component. When the content is above the lower limit, good abrasion resistance, on-ice performance (on-ice grip performance), etc. tend to be obtained. Moreover, the said content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 7 mass parts or less. By setting it below the upper limit, there is a tendency for good processability of the rubber composition to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² /g or more, more preferably 80 m ² /g or more, and even more preferably 100 m ² /g or more. By setting it above the lower limit, good abrasion resistance and performance on ice tend to be obtained. Further, the N ₂ SA is preferably 200 m ² /g or less, more preferably 150 m ² /g or less, and even more preferably 130 m ² /g or less. By setting the amount below the upper limit, good dispersibility of carbon black tends to be obtained.
Note that the nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

In addition, in the above-mentioned rubber composition, the total content of silica and carbon black is preferably 50 to 120 parts by mass based on 100 parts by mass of the rubber component from the viewpoint of overall performance of on-ice performance and abrasion resistance. . The amount is more preferably 55 parts by mass or more, and even more preferably 60 parts by mass or more. Moreover, 100 parts by mass or less is more preferable, and even more preferably 80 parts by weight or less.

(liquid plasticizer)
The rubber composition may also include a liquid plasticizer.
The above-mentioned liquid plasticizer is not particularly limited as long as it is a plasticizer in a liquid state at 20°C, and examples thereof include oil, liquid resin, liquid diene polymer, and the like. These may be used alone or in combination of two or more.

Examples of the oil include process oil, vegetable oil, or a mixture thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils 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 bran oil, safflower oil, sesame oil, and olive oil. , sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Commercially available products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd. Products from Nisshin Oilio Group Co., Ltd., etc. can be used.

The liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins) that are in a liquid state at 20°C, rosin resins, styrene resins, C5 resins, C9 resins, C5/C9 resins, Examples include dicyclopentadiene (DCPD) resin, coumaron indene resin (including coumaron and indene resin), phenol resin, olefin resin, polyurethane resin, acrylic resin, and the like.

Examples of the liquid diene-based polymer include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid IR), which is in a liquid state at 20°C. liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, liquid farnesene-butadiene copolymer, etc. It will be done. These may have their terminals or main chains modified with polar groups.

The content of the liquid plasticizer is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass, based on 100 parts by mass of the rubber component. Parts by mass or less. The lower limit is not particularly limited, and it is not necessary to include a liquid plasticizer, but from the viewpoint of performance on ice, it 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.

The rubber composition may include a resin (solid resin: resin that is solid at room temperature (25° C.)).

Examples of the resins (solid resins) include aromatic vinyl polymers, coumaron indene resins, coumaron resins, indene resins, phenolic resins, rosin resins, petroleum resins (C5 resins, C9 resins, etc.), and terpene resins. , acrylic resin, etc. Commercially available products include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nippon Chemical Co., Ltd., and Japan Co., Ltd. Catalysts made by JXTG Energy Corporation, Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., Toagosei Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among these, terpene-based resins, C5-based resins, and C9-based resins are preferable, since the effects of the present invention can be obtained more suitably.

The above-mentioned aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and/or styrene, and includes styrene homopolymer (styrene resin), α-methylstyrene homopolymer (α-methylstyrene resin), copolymers of styrene and other monomers, etc.

The above-mentioned coumaron indene resin is a resin containing coumaron and indene as the main monomer components constituting the resin skeleton (main chain). In addition to coumaron and indene, the monomer components contained in the skeleton include α-methyl Examples include styrene, methylindene, vinyltoluene, etc.

The above-mentioned coumaron resin is a resin containing coumaron as a main monomer component constituting the skeleton (main chain) of the resin.

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

Examples of the phenol resin include those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst. Among these, those obtained by reaction with an acid catalyst (such as novolac type phenol resin) are preferred.

Examples of the rosin resin include rosin resins typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

Examples of the petroleum resin include C5 resin, C9 resin, and the like.

As the C5 resin, C5 resin, dicyclopentadiene (DCPD) resin, etc. can be used. Moreover, these hydrogenated substances can also be used.

As the C9 resin, styrene/α-methylstyrene resin (a copolymer of α-methylstyrene and styrene), coumaron/indene/styrene resin, DCPD/C9 resin, C5/C9 resin, etc. can be used. Moreover, these hydrogenated substances can also be used.

As the terpene resin, a polyterpene resin obtained by polymerizing a terpene compound, an aromatic modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, etc. can be used. Moreover, these hydrogenated substances can also be used.

The above polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compounds are hydrocarbons and their oxygen-containing derivatives represented by the composition (C ₅ H ₈ ) _n , including monoterpenes (C ₁₀ H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), and diterpenes (C ₂₀ H It is a compound whose basic skeleton is a terpene classified as ₃₂ ), such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, Examples include terpineol, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, pinene/limonene resin, etc., which are made from the above-mentioned terpene compounds. Among these, pinene resin is preferred because it is easy to polymerize and is inexpensive because it uses natural pine resin as a raw material. Pinene resin usually contains both α-pinene and β-pinene, which are isomers. It is classified as α-pinene resin whose main component is pinene.

Examples of the aromatic modified terpene resin include terpene phenol resins made from the above terpene compounds and phenol compounds, and terpene styrene resins made from the above terpene compounds and styrene compounds. Moreover, terpene phenol styrene resins made from the above-mentioned terpene compounds, phenol compounds, and styrene compounds can also be used. Note that examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol, and the like. Furthermore, examples of styrene compounds include styrene, α-methylstyrene, and the like.

As the acrylic resin, a styrene acrylic resin such as a styrene acrylic resin, which has a carboxyl group and is obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, can be used. Among these, solvent-free carboxyl group-containing styrene acrylic resins can be preferably used.

The above-mentioned solvent-free carboxyl group-containing styrene acrylic resin is produced using a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (U.S. patent Specification No. 4,414,370, Japanese Patent Application Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Application Publication No. 1-313522, US Patent No. 5,010,166, Toagosei Research It is a (meth)acrylic resin (polymer) synthesized by the method described in Annual Report TREND 2000 No. 3, pages 42-45. In addition, in this specification, (meth)acrylic means methacryl and acrylic.

Examples of the acrylic monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), and (meth)acrylamide. , (meth)acrylic acid derivatives such as (meth)acrylamide derivatives. Note that (meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

Examples of the aromatic vinyl monomer component constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

Further, as a monomer component constituting the acrylic resin, other monomer components may be used in addition to (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

Among the above resins, when the main component of the rubber component (the rubber component with the largest amount of the rubber components) is isoprene rubber, it is preferable to use a terpene resin or a C5 resin, and When the main component of the rubber component is SBR, it is preferable to use C9 resin.

In the above rubber composition, the total content of the resin (solid resin) and liquid plasticizer is preferably 60 parts by mass or less based on 100 parts by mass of the rubber component, from the viewpoint of comprehensive performance of on-ice performance and abrasion resistance, The amount is more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less. The lower limit is not particularly limited, and it is not necessary to mix the resin and liquid plasticizer, but from the viewpoint of performance on ice, it is preferably 5 parts by mass or more, and more preferably 7 parts by mass or more.

Further, it is also a preferred embodiment that the content of the resin is 40 parts by mass or more based on 100 parts by mass of the rubber component. The content is more preferably 45 parts by mass or more per 100 parts by mass of the rubber component. Moreover, 50 parts by mass or less is preferable.
Furthermore, it is also preferable that the content of the resin based on 100 parts by mass of the rubber component is equal to or higher than the content of the water-soluble particles based on 100 parts by mass of the rubber component, since the effects of the present invention can be obtained more preferably.

(other materials)
The rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

The anti-aging agent is not particularly limited, but includes naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine. ; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylene p-phenylenediamine type anti-aging agents such as diamines; quinoline type anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methyl Monophenolic anti-aging agents such as phenol and styrenated phenol; bis, tris, and polyphenols such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane; Examples include anti-aging agents. Among these, p-phenylenediamine-based antiaging agents and quinoline-based antiaging agents are preferred, including N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 , 2-dihydroquinoline polymers are more preferred. As commercially available products, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis Co., Ltd., etc. can be used.

The content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more based on 100 parts by mass of the rubber component. By setting the value above the lower limit, sufficient ozone resistance tends to be obtained. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. By keeping it below the upper limit, a good tire appearance tends to be obtained.

The rubber composition preferably contains stearic acid. From the viewpoint of the overall performance, the content of stearic acid is preferably 0.5 to 10 parts by mass or more, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones can be used; for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. are used. can.

The rubber composition preferably contains zinc oxide. From the viewpoint of the overall performance, the content of zinc oxide is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the rubber component.

As the zinc oxide, conventionally known zinc oxides can be used, such as those manufactured by Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. products can be used.

The rubber composition may contain wax. The wax is not particularly limited, and includes petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically processing multiple waxes can also be used. These waxes may be used alone or in combination of two or more.

Examples of petroleum waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are waxes derived from resources other than petroleum; for example, vegetable waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; beeswax, lanolin, spermaceti wax, etc. animal waxes; mineral waxes such as ozokerite, ceresin, and petrolactam; and purified products thereof. As commercially available products, for example, products manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used. Note that the wax content may be appropriately set from the viewpoint of ozone resistance and cost.

Sulfur is preferably blended into the rubber composition from the standpoint of forming appropriate crosslinks in the polymer chains and imparting good overall performance.

The content of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 0.7 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 3.0 parts by mass or less. By keeping it within the above range, there is a tendency for good overall performance to be obtained.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. As commercially available products, products manufactured by Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Kanditsu Kogyo Co., Ltd., Hosoi Chemical Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
The content of the vulcanization accelerator is not particularly limited and may be determined freely according to the desired vulcanization rate and crosslinking density, but it is usually 0.3 to 10 parts by mass per 100 parts by mass of the rubber component. , preferably 0.5 to 7 parts by mass.

The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-Benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. Examples include sulfenamide vulcanization accelerators; guanidine vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

In addition to the above-mentioned components, the rubber composition may appropriately contain compounding agents commonly used in the tire industry, such as materials such as a mold release agent.

The above-mentioned rubber composition can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing the composition. .

As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30°C. The time is from seconds to 30 minutes, preferably from 1 minute to 30 minutes. In the final kneading step of kneading the vulcanizing agent and vulcanization accelerator, the kneading temperature is usually 100°C or less, preferably room temperature to 80°C. Further, a composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

The above rubber composition is manufactured by a common method. That is, it can be produced by kneading the above-mentioned components using a Banbury mixer, kneader, open roll, etc., and then vulcanizing the mixture.

The above rubber composition includes sidewalls, base treads, bead apex, clinch apex, inner liner, undertread, breaker topping, ply topping, tread (single layer tread, cap tread (cap layer) of multilayer tread, etc.), etc. It can be suitably used for each member of a tire, and can be particularly suitably used for a tread.

(tire)
The tire of the present invention is manufactured by a conventional method using the above rubber composition. That is, a rubber composition containing the above components is extruded in the unvulcanized stage to match the shape of each of the above components (tread, etc.), and then processed along with other tire components on a tire molding machine using the usual method. By molding, an unvulcanized tire is formed. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

Examples of the above-mentioned tires include pneumatic tires; run-flat tires; winter tires such as studless tires, studded tires, and snow tires; among these, winter tires are preferred, and studless tires are particularly preferred. It is. The studless tire can be suitably used as a studless tire for passenger cars.
Thus, a tire (preferably a winter tire, particularly preferably a studless tire) having a member (preferably a tread) made using the above-mentioned rubber composition is also part of the present invention.

In a tire having a tread made using the above rubber composition, the maximum thickness of the tread is preferably 5.5 mm or more. By setting the maximum thickness of the tread within such a range, the effects of the present invention can be more suitably achieved. The maximum thickness of the tread is more preferably 6.0 mm or more. Further, the diameter is preferably 10.0 mm or less, more preferably 9.5 mm or less, and even more preferably 9.0 mm or less.

An example of a preferred embodiment will be described below with reference to the drawings.
FIG. 1 shows the vicinity of a tire tread. Here, the tread refers to a member located outside the band layer 6 in the tire radial direction. In FIG. 1, the up-down direction is the radial direction of the tire, the left-right direction is the axial direction of the tire, and the direction perpendicular to the page is the circumferential direction of the tire.

The tread 1 has a radially outwardly convex shape. The tread 1 forms a tread surface 2 that contacts the road surface. A groove 3 is cut into the tread 1. These grooves 3 form a tread pattern. The tread 1 has a cap layer 4 and a base layer 5. The cap layer 4 is located radially outward of the base layer 5. The cap layer 4 is laminated on the base layer 5.

In FIG. 1, the symbol P is a point on the tread surface 2. Point P is located on the outer side of the groove 3 located furthest in the axial direction. The double-headed arrow T is the thickness of the tread 1 at the point P. Thickness T is the total thickness of cap layer 4 and base layer 5 at point P. This thickness T is measured along the normal line of the tread surface 2 at the point P. Although FIG. 1 shows an example of a two-layer tread 1 consisting of a cap layer 4 and a base layer 5, in the case of a single-layer tread 1, the thickness T of the tread is equal to the thickness T of the single-layer tread at that point P. In the case of a tread having a structure of three or more layers, the thickness T of the tread is the sum of the thicknesses of three or more layers at that point P, and in that case, the thickness T at point P is also the tread surface at that point P. It is measured along the normal of 2.

In FIG. 1, the maximum thickness of the tread 1 is the maximum dimension among the thicknesses of each tread at each point on the tread surface 2 (in FIG. 1, the sum of the thicknesses of the cap layer 4 and the base layer 5).

In FIG. 1, a band layer 6 comprising a band cord extends in the circumferential direction. A belt layer 7 is located inside the band layer 6 in the radial direction, and includes two belt cords that are inclined in the circumferential direction and extend in opposite directions. A carcass 8 is located inside the belt layer 7 in the radial direction, and the belt layer 7 reinforces the carcass 8. Furthermore, an inner liner 9 is located radially inside. The inner liner 9 is joined to the inner surface of the carcass 8.

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

Below, various chemicals used in Examples and Comparative Examples will be explained.
Natural rubber (NR): RSS#3
Butadiene rubber (BR): BR150B manufactured by Ube Industries (95% by mass or more of cis)
Styrene butadiene rubber (SBR): NS616 manufactured by Nippon Zeon Co., Ltd. (styrene content: 21% by mass)
Carbon black: Seast N220 manufactured by Mitsubishi Chemical Corporation
Silica: Uratsil VN3 (N ₂ SA172 m ² /g) manufactured by Evonik Degussa
Fine particle silica: Zeosil Premium 200MP (N ₂ SA 220 m ² /g) manufactured by Rhodia
Silane coupling agent: Si266 manufactured by Evonik Degussa
Silane coupling agent NXT: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive
Water-soluble particles A: those obtained by passing MN-00 manufactured by Umai Kasei Kogyo Co., Ltd. through a 500 mesh sieve (magnesium sulfate, median particle size (median diameter) 10 μm)
Water-soluble particles B: MN-00 manufactured by Umai Kasei Kogyo Co., Ltd. was passed through a 500-mesh sieve, and the sieve residue was passed through a 280-mesh sieve (magnesium sulfate, median particle size). 30μm)
Water-soluble particles C: MN-00 manufactured by Umai Kasei Kogyo Co., Ltd. was passed through a 200-mesh sieve, and the sieve residue was passed through a 120-mesh sieve (magnesium sulfate, median particle size). 100μm)
Water-soluble particles D: MN-00 manufactured by Umai Kasei Kogyo Co., Ltd. was passed through a 120-mesh sieve, and the sieve residue was passed through an 83-mesh sieve (magnesium sulfate, median particle size). 150μm)
Water-soluble particles E: Sodium lignin sulfonate manufactured by Tokyo Chemical Industry Co., Ltd. (median particle size (median diameter) 20 μm)
Wax: Ozoace wax manufactured by Nippon Seirin Co., Ltd. Anti-aging agent: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Oil: PS-32 (mineral oil [paraffinic process oil]) manufactured by Idemitsu Kosan Co., Ltd.
Resin: Petrotac 100V manufactured by Tosoh Corporation (C5/C9 resin, Mw 3800, softening point 96°C)
Stearic acid: Camellia zinc oxide manufactured by NOF Corporation: Zinc oxide manufactured by Mitsui Kinzoku Mining Co., Ltd. Class 2 sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Ouchi Shinko Chemical Industry Co., Ltd. ) made Noxela NS

[Measurement of median particle size (median diameter) of water-soluble particles]
The measurement was carried out using the SALD-2000J model manufactured by Shimadzu Corporation by a laser diffraction method (the measurement procedure is as follows).
<Measurement operation>
Water-soluble particles were dispersed at room temperature in a mixed solution of a dispersion solvent (toluene) and a dispersant (10% by mass di-2-ethylhexyl sodium sulfosuccinate/toluene solution), and the resulting dispersion was irradiated with ultrasound. While stirring, the dispersion was stirred for 5 minutes to obtain a test solution. The test solution was transferred to a batch cell and measured after 1 minute. (Refractive index: 1.70-0.20i)

<Examples and comparative examples>
According to the formulation shown in Tables 1 to 3, using a 1.7L Banbury mixer, natural rubber and silica, and butadiene rubber and silica were added and kneaded for 3 minutes at 150°C. batch) was obtained. Next, materials other than sulfur and a vulcanization accelerator were added to the obtained masterbatch, and the mixture was kneaded for 2 minutes at 150°C to obtain a kneaded product. Further, sulfur and a vulcanization accelerator were added and kneaded using open rolls at 80° C. for 5 minutes to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press-vulcanized at 170° C. for 12 minutes using a 0.5 mm thick mold to obtain a vulcanized rubber composition.

In addition, each of the obtained unvulcanized rubber compositions was molded into the shape of a cap tread, laminated together with other tire members, and vulcanized at 170°C for 15 minutes to produce a test studless tire (tire size: 195 /65R15) was produced.

The obtained vulcanized rubber composition and test studless tires were stored at room temperature in the dark for three months, and then evaluated as follows. The results are shown in Tables 1 to 3.

<Ice performance>
Using the test studless tires, the performance of the actual vehicle on ice was evaluated under the following conditions. The test was conducted at the Hokkaido Nayoro test course of Sumitomo Rubber Industries, Ltd., and the temperature was -1°C. The test tires were attached to a domestically produced 2000cc FR vehicle, and the stopping distance on ice required to stop the vehicle by pressing the lock brake at 30 km/h was measured. Calculation was performed using the following formula using Comparative Example 1 in Table 1, Comparative Example 11 in Table 2, and Comparative Example 21 in Table 3, respectively. The larger the index, the better the performance on ice.
(Ice performance) = (Reference braking stopping distance) / (Stopping distance of each formulation) x 100

<Wet grip performance>
Test studless tires were attached to all wheels of a vehicle (Japanese FF 2000cc), and the braking distance from an initial speed of 100 km/h was determined on a wet asphalt road surface. The braking distance of the standard comparative example (comparative example 21) was set as 100, and each formulation was expressed as an index. The larger the index, the better the wet grip performance.

<Abrasion resistance>
The vulcanized rubber composition was tested using a Lambourne abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd. under conditions of a surface rotation speed of 50 m/min, an additional load of 3.0 kg, a falling sand amount of 15 g/min, and a slip rate of 20%. , the amount of wear was measured, and the reciprocal of the amount of wear was calculated. In Table 1, the reciprocal of the wear amount of Comparative Example 1 is set to 100, in Table 2, the reciprocal of the wear amount of Comparative Example 11 is set to 100, and in Table 3, the reciprocal of the wear amount of Comparative Example 21 is set to 100. The reciprocal of the amount was expressed as an index. The larger the index, the better the wear resistance.

<Overall performance>
In Tables 1 and 2, the sum of the indices of on-ice performance and abrasion resistance was evaluated as the overall performance, and in Table 3, the sum of the indices of on-ice performance, wet grip performance, and abrasion resistance was evaluated as the overall performance.

<Maximum tread thickness>
The maximum thickness of the tread (maximum total thickness of the cap layer and base layer) of the test studless tire of Example 24 was measured and found to be 5.5 mm.

From Tables 1 to 3, in the examples containing isoprene rubber, conjugated diene polymer, and water-soluble particles, and in which the median particle size of the water-soluble particles is less than or equal to the predetermined value, the overall on-ice performance and abrasion resistance We were able to improve performance.

1 Tread 2 Tread surface 3 Groove 4 Cap layer 5 Base layer 6 Band layer 7 Belt layer 8 Carcass 9 Inner liner P Point T on tread surface 2 Thickness of tread 1

Claims (15)

A rubber component containing isoprene rubber and a conjugated diene polymer, and water-soluble particles,
the water-soluble particles are magnesium sulfate,
A rubber composition for a tire, in which the water-soluble particles satisfy the following formula (I).
10≦ D50≦30 (I)
(D50 in formula (I) represents the median particle size (μm) of water-soluble particles.) The rubber composition for a tire according to claim 1, wherein the water-soluble particles satisfy the following formula (II).
A/D50≧0.5 (II)
(A in formula (II) represents the content (parts by mass) of water-soluble particles with respect to 100 parts by mass of the rubber component. D50 represents the median particle size (μm) of the water-soluble particles.) The rubber composition for a tire according to claim 1 or 2, wherein the content of the water-soluble particles is 10 parts by mass or more based on 100 parts by mass of the rubber component. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of the water-soluble particles is 25 parts by mass or more based on 100 parts by mass of the rubber component. The rubber composition further contains silica,
The content of isoprene-based rubber in 100% by mass of the rubber component is 20% by mass or more, the content of the conjugated diene-based polymer is 20% by mass or more,
The rubber composition for tires according to any one of claims 1 to 4, wherein the silica content is 50% by mass or more in 100% by mass of the total content of silica and carbon black. The rubber composition for a tire according to any one of claims 1 to 5, wherein the content of the liquid plasticizer is 30 parts by mass or less based on 100 parts by mass of the rubber component. 7. The tire rubber composition according to claim 1, wherein the conjugated diene polymer contains a conjugated diene polymer having a cis content of 90% by mass or more. The rubber composition for tires according to any one of claims 1 to 7, wherein the water-soluble particles have a median particle size of 10 μm or more. The rubber component further includes styrene butadiene rubber,
The rubber composition for a tire according to any one of claims 1 to 8, wherein the content of styrene-butadiene rubber in 100 parts by mass of the rubber component is greater than or equal to the content of water-soluble particles in 100 parts by mass of the rubber component. The rubber composition further contains particulate silica having a nitrogen adsorption specific surface area of 180 m ² /g or more,
The rubber composition for tires according to any one of claims 1 to 9, wherein the content of particulate silica per 100 parts by mass of the rubber component is greater than or equal to the content of water-soluble particles per 100 parts by mass of the rubber component. The rubber composition further includes a resin,
The rubber composition for a tire according to any one of claims 1 to 10, wherein the content of the resin based on 100 parts by mass of the rubber component is greater than or equal to the content of the water-soluble particles based on 100 parts by mass of the rubber component. The rubber composition further includes a resin,
The rubber composition for tires according to any one of claims 1 to 11, wherein the resin is at least one selected from the group consisting of terpene resins, C5 resins, and C9 resins. A tire comprising a member made using the rubber composition according to any one of claims 1 to 12. 14. The tire according to claim 13, wherein the tire is a winter tire and the member is a tread. The tire according to claim 14, wherein the maximum thickness of the tread is 5.5 mm or more.

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