阅读说明：本技术 轮胎用橡胶组合物和无钉轮胎 (Rubber composition for tire and studless tire ) 是由 影山裕一 木村和资 三原谕 山元裕太郎 于 2019-03-19 设计创作，主要内容包括：本发明的目的是提供冰上性能和耐磨损性能优异的轮胎用橡胶组合物、以及使用上述轮胎用橡胶组合物的无钉轮胎。本发明的轮胎用橡胶组合物,含有二烯系橡胶100质量份和热膨胀性微胶囊复合体1～30质量份,所述热膨胀性微胶囊复合体含有1个以上的热膨胀性微胶囊、和覆盖所述1个以上的热膨胀性微胶囊的丙烯腈丁二烯共聚物和/或其交联体。(The purpose of the present invention is to provide a rubber composition for a tire having excellent on-ice performance and wear resistance, and a studless tire using the rubber composition for a tire. The rubber composition for a tire of the present invention comprises 100 parts by mass of a diene rubber and 1 to 30 parts by mass of a heat-expandable microcapsule complex comprising 1 or more heat-expandable microcapsules and an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof covering the 1 or more heat-expandable microcapsules.)

1. A rubber composition for a tire comprising 100 parts by mass of a diene rubber and 1 to 30 parts by mass of a heat-expandable microcapsule complex,

the heat-expandable microcapsule composite contains 1 or more heat-expandable microcapsules and an acrylonitrile-butadiene copolymer and/or a crosslinked material thereof covering the 1 or more heat-expandable microcapsules.

2. The rubber composition for a tire according to claim 1, wherein the 1 or more thermally-expansible microcapsules are a plurality of thermally-expansible microcapsules.

3. The rubber composition for a tire according to claim 2, wherein the plurality of thermally-expansible microcapsules are connected in a linear, ribbon-like or cluster-like manner.

4. The rubber composition for a tire according to any one of claims 1 to 3, wherein the heat-expandable microcapsule complex comprises 1 or more heat-expandable microcapsules and a crosslinked product of an acrylonitrile-butadiene copolymer covering the 1 or more heat-expandable microcapsules,

the crosslinked material is a crosslinked material of an acrylonitrile butadiene copolymer having a carboxyl group or an amino group and an isocyanate.

5. The rubber composition for a tire as claimed in claim 4, wherein the isocyanate is at least 1 isocyanate selected from the group consisting of isocyanate silane, diisocyanate and polyfunctional isocyanate.

6. The rubber composition for a tire according to any one of claims 1 to 5, wherein the heat-expandable microcapsule composite further contains a nonionic surfactant,

the content of the nonionic surfactant is 5 to 50% by mass relative to the content of the acrylonitrile-butadiene copolymer and/or the crosslinked material thereof.

7. The rubber composition for a tire according to any one of claims 1 to 6, further comprising carbon black and/or a white filler.

8. The rubber composition for a tire according to any one of claims 1 to 7, further comprising three-dimensionally crosslinked polymer fine particles having an average particle diameter of 1 to 200 μm,

the content of the polymer fine particles is 1 to 30 parts by mass per 100 parts by mass of the diene rubber.

9. The rubber composition for a tire according to any one of claims 1 to 8, wherein the content of the heat-expandable microcapsule contained in the heat-expandable microcapsule composite is 1 to 15 parts by mass with respect to 100 parts by mass of the diene rubber.

10. A studless tire having a tread portion manufactured using the rubber composition for a tire according to any one of claims 1 to 9.

Technical Field

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

Background

Conventionally, in order to improve the on-ice friction of studless tires, a rubber composition for tires containing heat-expandable microcapsules has been studied.

For example, patent document 1 discloses "a heat-expandable microcapsule composite characterized by having a structure in which a plurality of heat-expandable microcapsules are attached to cellulose fibers. ". Patent document 1 describes that the performance on ice of studless tires is improved by blending the heat-expandable microcapsule composite in a rubber composition.

Disclosure of Invention

Problems to be solved by the invention

Recently, with an increase in the level of safety required, further improvement in the on-ice performance (on-ice braking performance) of studless tires is required. In addition, the wear resistance is also required to be compatible.

Under such circumstances, the present inventors have made reference to examples of patent document 1 to prepare a rubber composition for a tire and evaluated the same, and as a result, have found that further improvement in the on-ice performance and the wear resistance is desired.

In view of the above circumstances, an object of the present invention is to provide a rubber composition for a tire excellent in on-ice performance and wear resistance, and a studless tire using the rubber composition for a tire.

Means for solving the problems

The present inventors have intensively studied the above-mentioned problems, and as a result, they have found that the above-mentioned problems can be solved by using a heat-expandable microcapsule composite comprising heat-expandable microcapsules and an acrylonitrile butadiene copolymer and/or a crosslinked product thereof covering the heat-expandable microcapsules, and have completed the present invention.

That is, the present inventors have found that the above problems can be solved by the following means.

[1] A rubber composition for a tire comprising 100 parts by mass of a diene rubber and 1 to 30 parts by mass of a heat-expandable microcapsule complex,

the heat-expandable microcapsule composite contains 1 or more heat-expandable microcapsules and an acrylonitrile-butadiene copolymer and/or a crosslinked material thereof covering the 1 or more heat-expandable microcapsules.

[2] The rubber composition for a tire according to [1], wherein the 1 or more thermally-expansible microcapsules are a plurality of thermally-expansible microcapsules.

[3] The rubber composition for a tire according to [2], wherein the plurality of thermally-expansible microcapsules are connected in a linear, ribbon-like or cluster-like manner.

[4] The rubber composition for a tire according to any one of [1] to [3], wherein the heat-expandable microcapsule complex comprises 1 or more heat-expandable microcapsules and a crosslinked product of an acrylonitrile-butadiene copolymer covering the 1 or more heat-expandable microcapsules,

the crosslinked material is a crosslinked material of an acrylonitrile butadiene copolymer having a carboxyl group or an amino group and an isocyanate.

[5] The rubber composition for a tire according to [4], wherein the isocyanate is at least 1 isocyanate selected from the group consisting of isocyanate silane, diisocyanate and polyfunctional isocyanate.

[6] The rubber composition for a tire according to any one of [1] to [5], wherein the heat-expandable microcapsule composite further contains a nonionic surfactant,

the content of the nonionic surfactant is 5 to 50% by mass relative to the content of the acrylonitrile-butadiene copolymer and/or the crosslinked material thereof.

[7] The rubber composition for a tire according to any one of [1] to [6], further comprising carbon black and/or a white filler.

[8] The rubber composition for a tire according to any one of [1] to [7], further comprising three-dimensionally crosslinked polymer fine particles having an average particle diameter of 1 to 200 μm,

the content of the polymer fine particles is 1 to 30 parts by mass per 100 parts by mass of the diene rubber.

[9] The rubber composition for a tire according to any one of [1] to [8], wherein the content of the heat-expandable microcapsule contained in the heat-expandable microcapsule composite is 1 to 15 parts by mass with respect to 100 parts by mass of the diene rubber.

[10] A studless tire having a tread portion manufactured using the rubber composition for a tire according to any one of [1] to [9].

Effects of the invention

As shown below, the present invention can provide a rubber composition for a tire excellent in on-ice performance and wear resistance, and a studless tire using the rubber composition for a tire.

Drawings

FIG. 1 is a photomicrograph of an embodiment of a particular composite.

Fig. 2 is a schematic partial cross-sectional view of an example of the studless tire according to the embodiment of the present invention.

Detailed Description

The rubber composition for a tire of the present invention and a studless tire using the rubber composition for a tire are described below.

In the present specification, the numerical range expressed by the term "to" means a range including the numerical values described before and after the term "to" as the lower limit value and the upper limit value.

Further, the rubber composition for a tire of the present invention may contain 1 kind of each component alone, or 2 or more kinds of each component in combination. Here, when 2 or more kinds of the components are used in combination, the content of the component refers to the total content unless otherwise specified.

[ rubber composition for tires ]

The rubber composition for a tire of the present invention (hereinafter, also referred to as "the composition of the present invention") contains: 100 parts by mass of diene rubber and 1 to 30 parts by mass of a heat-expandable microcapsule composite.

Here, the heat-expandable microcapsule composite includes 1 or more heat-expandable microcapsules and an acrylonitrile-butadiene copolymer and/or a crosslinked material thereof covering the 1 or more heat-expandable microcapsules.

It is considered that the composition of the present invention can obtain the above-mentioned effects by adopting the above-mentioned constitution. Although the reason is not clear, the reason is presumed to be as follows.

Since the composition of the present invention contains the heat-expandable microcapsules, the heat-expandable microcapsules increase the frictional force with the road surface by absorbing water on ice, resulting in an increase in the performance on ice. Further, the present inventors have found that when a plurality of thermally expandable microcapsules are connected together, water is efficiently absorbed, and therefore the performance on ice is higher.

Here, the inventors have found, after investigation, that in the case of manufacturing a studless tire by merely blending the heat-expandable microcapsules in the rubber composition for a tire, abrasion may progress from the heat-expandable microcapsules due to friction between the studless tire and a road surface. On the other hand, it is considered that since the heat-expandable microcapsule in the composition of the present invention is covered with the acrylonitrile butadiene copolymer and/or the crosslinked material thereof (coating layer), the coating layer absorbs stress and suppresses progress of abrasion.

It is presumed that for this reason, the composition of the present invention exhibits excellent on-ice properties and wear resistance.

The components contained in the composition of the present invention will be specifically described below.

[ diene rubber ]

The diene rubber contained in the composition of the present invention is not particularly limited, and examples thereof include Natural Rubber (NR), Isoprene Rubber (IR), Butadiene Rubber (BR), nitrile rubber (NBR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), butyl rubber (IIR), halogenated butyl rubber (BR-IIR, Cl-IIR), Chloroprene Rubber (CR), and derivatives of these various rubbers.

The diene rubber preferably contains at least 1 of these rubbers in a total amount of 30 mass% or more, for the reason that the effect of the present invention is more excellent.

The diene rubber preferably contains Natural Rubber (NR) or Butadiene Rubber (BR), more preferably contains Natural Rubber (NR) and Butadiene Rubber (BR), and preferably contains Natural Rubber (NR) and Butadiene Rubber (BR) each in an amount of 30 to 70% by mass, and more preferably 40 to 60% by mass, based on the reason that the effect of the present invention is more excellent.

The weight molecular weight (Mw) of the diene rubber is not particularly limited, but is preferably 100,000 to 10,000,000, more preferably 200,000 to 1,500,000, and even more preferably 300,000 to 3,000,000, for the reason that the effect of the present invention is excellent.

The number average molecular weight (Mn) of the diene rubber is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 100,000 to 750,000, and even more preferably 150,000 to 1,500,000, because of the excellent effects of the present invention.

The Mw and/or Mn of at least 1 of the diene rubbers included in the diene rubbers is preferably within the above range, and more preferably, the Mw and/or Mn of all the diene rubbers included in the diene rubbers is within the above range.

In the present specification, Mw and Mn are standard polystyrene conversion values obtained by Gel Permeation Chromatography (GPC) measurement under the following conditions.

Solvent: tetrahydrofuran (THF)

The detector: RI detector

[ specific Complex ]

The heat-expandable microcapsule composite contained in the composition of the present invention is a composite (hereinafter, also referred to as "specific composite") containing 1 or more heat-expandable microcapsules and an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof covering the 1 or more heat-expandable microcapsules. That is, the specific composite has a structure in which 1 or more thermally expandable microcapsules are covered with a coating layer made of an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof.

FIG. 1 shows a photomicrograph of one embodiment of a particular composite. In fig. 1, mainly a plurality of thermal expansion microcapsules are covered with a coating layer.

< thermally expandable microcapsules >

The thermally expandable microcapsule is formed of thermoplastic resin particles in which a substance that vaporizes or expands by heat to generate a gas is encapsulated. Here, the heat-expandable microcapsule is a microcapsule in which a gas is encapsulated in an outer shell made of a thermoplastic resin by heating at a temperature (for example, 130 to 190 ℃) equal to or higher than the vaporization or expansion start temperature of the above substance.

The particle size of the thermally expandable microcapsules before expansion is preferably 5 to 300 μm, more preferably 10 to 200 μm, from the viewpoint of further improving the effect of the present invention.

As the thermoplastic resin, for example, a polymer of (meth) acrylonitrile and/or a copolymer having a high (meth) acrylonitrile content can be preferably used. As other monomers (comonomers) in the case of the copolymer, monomers such as vinyl halide, vinylidene halide, styrene-based monomer, (meth) acrylate-based monomer, vinyl acetate, butadiene, vinylpyridine, chloroprene, and the like are used.

The thermoplastic resin can be crosslinked with a crosslinking agent such as divinylbenzene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1, 3-butanediol di (meth) acrylate, allyl (meth) acrylate, 1,3, 5-triacryloylhexahydro-1, 3, 5-triazine, or triallyl isocyanurate. The crosslinked form is preferably uncrosslinked, but may be partially crosslinked to such an extent that the properties as a thermoplastic resin are not impaired.

Specific examples of the substance that generates a gas by being gasified or expanded by heat, which is contained in the thermally expandable microcapsule, include hydrocarbons such as n-pentane, isopentane, neopentane, butane, isobutane, hexane, and petroleum ether; chlorinated hydrocarbons such as methyl chloride, methylene chloride, ethylene dichloride, trichloroethane, and trichloroethylene; and the like, or solids such as azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, toluenesulfonyl hydrazide derivatives, aromatic succinyl hydrazide derivatives, and the like.

As such heat-expandable microcapsules, commercially available products such as, for example, スウェーデン, trade names "エクスパンセル 091 DU-80", "エクスパンセル 092 DU-120" available from EXPANCEL, trade names "マツモトマイクロスフェアー F-85", "マツモトマイクロスフェアー F-100" and "マツモトマイクロスフェアー F-100D" available from Songban oil & fat pharmaceuticals can be used.

As described above, the specific composite has a structure in which 1 or more thermally expandable microcapsules are covered with a coating layer made of an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof. The specific composite preferably has a structure in which a plurality of (2 or more) heat-expandable microcapsules are covered with a coating layer made of an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof, for the reason that the effect of the present invention is more excellent. The plurality of thermally expandable microcapsules are preferably connected in a linear, ribbon-like or cluster-like manner, because the effect of the present invention is more excellent.

The content of the heat-expandable microcapsule contained in the specific composite in the composition of the present invention is not particularly limited, and is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and still more preferably 3 to 10 parts by mass based on 100 parts by mass of the diene rubber, from the viewpoint of further improving the effect of the present invention.

The proportion of the thermally expandable microcapsules in the specific composite is not particularly limited, but is preferably 10 to 90 mass%, more preferably 30 to 70 mass%, from the viewpoint of further improving the effect of the present invention.

< coating layer >

As described above, the specific composite has a structure in which 1 or more thermally expandable microcapsules are covered with a coating layer made of an acrylonitrile-butadiene copolymer and/or a crosslinked product thereof.

The coating layer is not particularly limited as long as it is an acrylonitrile butadiene copolymer and/or a crosslinked product thereof, and is preferably a crosslinked product of an acrylonitrile butadiene copolymer, because the effect of the present invention is more excellent.

In the present specification, the covering layer of the acrylonitrile-butadiene copolymer and/or the crosslinked product thereof is not included in the diene rubber.

The content of the repeating unit derived from acrylonitrile (acrylonitrile content) in the acrylonitrile butadiene copolymer and/or the crosslinked material thereof is not particularly limited, but is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of further improving the effect of the present invention.

The coating layer preferably has a urethane bond (-NH-C (═ O) -O-) or a urea bond (-NH-C (═ O) -NH-), and more preferably has a urethane bond, from the viewpoint of further improving the effects of the present invention.

In the case where the coating layer is a crosslinked product of an acrylonitrile butadiene copolymer, the crosslinked product is preferably a crosslinked product of an acrylonitrile butadiene copolymer having a carboxyl group or an amino group and an isocyanate, and more preferably a crosslinked product of an acrylonitrile butadiene copolymer having a carboxyl group and an isocyanate, from the viewpoint that the effect of the present invention is more excellent.

The content of the coating layer in the composition of the present invention is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and still more preferably 3 to 10 parts by mass based on 100 parts by mass of the diene rubber, for the reason that the effect of the present invention is more excellent.

The proportion of the coating layer in the specific composite is not particularly limited, but is preferably 10 to 90% by mass, more preferably 30 to 70% by mass, from the viewpoint of further improving the effect of the present invention.

The content of the coating layer in the specific composite is not particularly limited, but is preferably 50 to 200 mass%, more preferably 70 to 130 mass%, from the viewpoint of further improving the effect of the present invention.

< nonionic surfactant >

The specific composite preferably further contains a nonionic surfactant, because the effect of the present invention is more excellent.

The nonionic surfactant is not particularly limited, and specific examples thereof include sorbitan fatty acid esters, polyoxyethylene higher alcohol ethers, polyoxyethylene-propylene higher alcohol ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkylphenols, polyoxyethylene aliphatic hydrocarbon amines (e.g., polyoxyethylene alkylamines, polyoxyethylene alkyleneamines), polyoxyethylene aliphatic hydrocarbon amides (e.g., polyoxyethylene alkylamides, polyoxyethylene alkyleneamides), and polyoxyethylene-polyoxypropylene block polymers.

The nonionic surfactant preferably has an amide group or an amino group, and more preferably an amide group, because the effect of the present invention is more excellent.

The content of the nonionic surfactant is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and still more preferably 0.3 to 2 parts by mass per 100 parts by mass of the diene rubber, from the viewpoint of further improving the effect of the present invention.

The proportion of the nonionic surfactant in the specific composite is not particularly limited, but is preferably 1 to 20% by mass, more preferably 5 to 10% by mass, from the viewpoint of further improving the effect of the present invention.

The content of the nonionic surfactant in the specific composite is not particularly limited, but is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of further improving the effect of the present invention.

< method for producing specific composite >

The method for producing the specific composite is not particularly limited, and examples thereof include a method of mixing the heat-expandable microcapsules with an acrylonitrile-butadiene copolymer.

In the case where the coating layer of the specific composite is a crosslinked product of an acrylonitrile butadiene copolymer, the method for producing the specific composite is preferably a method for obtaining the specific composite by crosslinking an acrylonitrile butadiene copolymer in a liquid polymer containing a heat-expandable microcapsule (hereinafter, also referred to as "method 1 of the present invention"), from the viewpoint of further improving the ice performance and the wear resistance of the obtained composition of the present invention. Among them, from the viewpoint of more excellent on-ice performance and abrasion resistance of the obtained composition of the present invention, a method of obtaining a specific composite by reacting an acrylonitrile butadiene copolymer having a carboxyl group or an amino group with an isocyanate in a liquid polymer containing a thermally expandable microcapsule is more preferable (hereinafter, also referred to as "method 2 of the present invention"). In the methods 1 and 2 of the present invention, it is preferable to further blend a nonionic surfactant in the liquid polymer for the reason that the obtained composition of the present invention is more excellent in the ice performance and the abrasion resistance.

Hereinafter, the phrase "the obtained composition of the present invention is more excellent in the on-ice performance and the abrasion resistance" will be simply referred to as "the effect of the present invention is more excellent".

When a crosslinked material is formed in the liquid polymer, the liquid polymer is separated from the crosslinked material, and the crosslinked material (coating layer) is formed so as to cover the plurality of thermally expandable microcapsules, and the plurality of thermally expandable microcapsules in the coating layer are connected in a linear, band-like or cluster-like manner. As a result, the resulting composition of the present invention exhibits more excellent on-ice properties and wear resistance.

The respective components used in the methods 1 and 2 of the present invention will be described below.

(Heat-expandable microcapsules)

The thermally expandable microcapsules are as described above.

(liquid Polymer)

The liquid polymer is not particularly limited, and specific examples thereof include liquid polybutadiene, liquid polystyrene butadiene, liquid polyisoprene, and the like. Among these, liquid polybutadiene is preferable because the effect of the present invention is more excellent.

The number average molecular weight (Mn) of the liquid polymer is preferably 1,000 or more and less than 50,000, more preferably 5,000 to 40,000, even more preferably 6,000 to 30,000, and particularly preferably 7,000 to 20,000, from the viewpoint of further improving the effects of the present invention.

(Acrylonitrile butadiene copolymer having carboxyl group or amino group)

The acrylonitrile butadiene copolymer having a carboxyl group or an amino group is not particularly limited, but an acrylonitrile butadiene copolymer having a carboxyl group or an amino group at the terminal is preferable because the effect of the present invention is more excellent. Further, the acrylonitrile butadiene copolymer having a carboxyl group forms a urethane bond by a reaction with isocyanate, and the acrylonitrile butadiene copolymer having an amino group forms a urea bond by a reaction with isocyanate.

The content of acrylonitrile (acrylonitrile content) in the acrylonitrile butadiene copolymer having a carboxyl group or an amino group is not particularly limited, but is preferably 5 to 50 mass%, more preferably 10 to 30 mass%, and still more preferably 17 to 25 mass% from the viewpoint of further improving the effect of the present invention.

The molecular weight of the acrylonitrile butadiene copolymer having a carboxyl group or an amino group is preferably 1,000 to 50,000, more preferably 2,000 to 10,000, and still more preferably 3,000 to 5,000, from the viewpoint of further improving the effect of the present invention.

(isocyanate)

The isocyanate is not particularly limited, and specific examples thereof include isocyanate silane, diisocyanate, polyfunctional isocyanate, and the like. The isocyanate is preferably a polyfunctional isocyanate (isocyanate having 2 or more isocyanate groups) because the effect of the present invention is more excellent.

Specific examples of the polyfunctional isocyanate include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylenediamine diisocyanate, 1, 5-naphthalene diisocyanate, and triphenylmethane triisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine isocyanate, norbornane diisocyanate, trans-cyclohexane-1, 4-diisocyanate, isophorone diisocyanate, bis (isocyanatomethyl) cyclohexane, and dicyclohexylmethane diisocyanate; isocyanurate bodies, biuret bodies, and adduct bodies thereof; and the like.

(nonionic surfactant)

The nonionic surfactant is as described above.

< content >

The content of the specific composite in the composition of the present invention is 1 to 30 parts by mass per 100 parts by mass of the diene rubber. Among them, from the reason of the invention of excellent effect, preferably from 5 to 20 mass portions.

[ Arbitrary composition ]

The composition of the present invention may contain components (optional components) other than the above components as required.

Examples of such components include various additives generally used in rubber compositions, such as carbon black, a white filler (preferably silica), a silane coupling agent, a terpene resin (preferably an aromatic modified terpene resin), a thermally expandable microcapsule, zinc oxide, stearic acid, an antioxidant, wax, a processing aid, process oil, a liquid polymer, a thermosetting resin, a vulcanizing agent (e.g., sulfur), and a vulcanization accelerator.

< carbon black and/or white filler >

The composition of the present invention preferably contains carbon black and/or a white filler, and further preferably contains both carbon black and a white filler, from the viewpoint of further improving the effects of the present invention.

(carbon Black)

The carbon black is not particularly limited, and examples thereof include various grades such as SAF-HS, SAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF-LS, FEF, GPF, and SRF.

The nitrogen adsorption specific surface area (N) of the carbon black₂SA), but is preferably 50 to 200m from the viewpoint of further improving the effect of the present invention²A more preferable range is 70 to 150m²/g。

Here, the nitrogen adsorption specific surface area (N)₂SA) is a resin composition according to JIS K6217-2: 2001 "section 2: the specific surface area method-nitrogen adsorption method-single-point method "is a value obtained by measuring the amount of nitrogen adsorbed on the surface of carbon black.

< white filler >

The white filler is not particularly limited, and examples thereof include silica, calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide, calcium sulfate, and the like. Among these, silica is preferable because of its excellent effect of the present invention.

The silica is not particularly limited, and examples thereof include wet silica (hydrated silicic acid), dry silica (silicic anhydride), calcium silicate, and aluminum silicate. Among these, wet silica is preferable because of its excellent effect of the present invention.

The specific surface area of cetyl trimethylammonium bromide (CTAB) adsorption of the silica is not particularly limited, and is preferably 100 to 400m for the reason that the effect of the present invention is excellent²A concentration of 150 to 300m²A more preferable range is 160 to 250 m/g²/g。

Here, the CTAB adsorption specific surface area is in accordance with JIS K6217-3: 2001 "section 3: the expression of specific surface area-CTAB adsorption method "measures the value of CTAB adsorption amount on the silica surface.

In the composition of the present invention, the content (total content in the case of using both carbon black and white filler) of the carbon black and/or white filler (particularly silica) is preferably 30 to 100 parts by mass based on 100 parts by mass of the diene rubber, because the effect of the present invention is more excellent. Among them, the amount is more preferably 40 to 90 parts by mass, and still more preferably 45 to 80 parts by mass.

In the composition of the present invention, the content of the carbon black is preferably 10 to 50 parts by mass, more preferably 15 to 45 parts by mass, and still more preferably 20 to 40 parts by mass, based on 100 parts by mass of the diene rubber, for the reason that the effect of the present invention is excellent.

In the composition of the present invention, the content of the white filler (particularly, silica) is preferably 10 to 80 parts by mass, more preferably 15 to 60 parts by mass, and still more preferably 20 to 50 parts by mass, based on 100 parts by mass of the diene rubber, for the reason that the effect of the present invention is more excellent.

[ specific particles ]

The composition of the present invention preferably contains three-dimensionally crosslinked polymer fine particles (hereinafter, also referred to as "specific fine particles") having an average particle diameter of 1 to 200 μm, for the reason that the effect of the present invention is more excellent.

For the reason that the effect of the present invention is more excellent, the average particle diameter of the specific fine particles is preferably 1 to 50 μm, and more preferably 6 to 40 μm.

Here, the average particle diameter is an average value of equivalent circle diameters measured by a laser microscope.

Specific examples of the polymer constituting the specific fine particles include polyether-based, polyester-based, polyolefin-based, polycarbonate-based, aliphatic-based, saturated hydrocarbon-based, acrylic-based, or plant-derived polymers or copolymers.

Examples of the polyether polymer or copolymer include polyethylene glycol, polypropylene glycol (PPG), polyglycerol, an ethylene oxide/propylene oxide copolymer, polytetramethylene ether glycol (PTMEG), and sorbitol polyol.

Examples of the polyester-based polymer or copolymer include condensates (condensation polyester polyols) of low-molecular polyvalent alcohols (e.g., ethylene glycol, diethylene glycol, propylene glycol, etc.) with polycarboxylic acids (e.g., adipic acid, sebacic acid, terephthalic acid, isophthalic acid, etc.); a lactone-type polyol; and the like.

Examples of the polyolefin-based polymer or copolymer include polyethylene, polypropylene, ethylene-propylene copolymer (EPR, EPDM), polybutene, polyisobutylene, and hydrogenated polybutadiene.

Examples of the polycarbonate-based polymer or copolymer include transesterification products of a polyol compound (e.g., 1, 6-hexanediol, 1, 4-butanediol, 1, 5-pentanediol, etc.) and a dialkyl carbonate.

Further, as the acrylic polymer or copolymer, for example, acrylic polyol; homopolymers of acrylic esters such as acrylic ester, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; an acrylate copolymer comprising a combination of 2 or more of these acrylates; and the like.

Examples of the plant-derived polymer or copolymer include polydiol acid, polylactic acid, polybutylene succinate, and polytrimethylene terephthalate.

Among these, polyether polymers or copolymers are preferable, and polypropylene glycol is more preferable, because the effect of the present invention is more excellent.

The specific fine particles preferably have a siloxane bond because the effect of the present invention is more excellent.

(method for producing specific Fine particles)

The method for producing the specific fine particles is not particularly limited, but from the reason that the effect of the present invention is more excellent, a method of crosslinking a polymer (for example, the above-mentioned polymer) in a liquid polymer with a crosslinking agent or the like to obtain the specific fine particles is preferable, and a method of reacting polymers (preferably polyether polymers or copolymers, and more preferably polypropylene glycol) having hydrolyzable silyl groups (preferably alkoxysilyl groups) at the ends thereof in a liquid polymer (hydrolyzable silyl groups are reacted with each other) to obtain the specific fine particles is more preferable. When the hydrolyzable silyl groups are reacted with each other, a condensation catalyst is preferably used for the reason that the effect of the present invention is more excellent. Examples of the condensation catalyst include dibutyltin dilaurate, dibutyltin dioleate, dibutyltin diacetate, tetrabutyl titanate, stannous octoate, and octyltin compounds.

The polymer fine particles dispersed in the liquid polymer can be obtained by crosslinking the polymer in the liquid polymer. The liquid polymer is the same as the liquid polymer described in the above specific composite.

The average particle diameter of the specific fine particles can be controlled by the molecular weight of the polymer before crosslinking, the ratio of the amount of the liquid polymer to the amount of the polymer, the reaction temperature, and the like.

As another mode of the specific fine particles, for example, the ones described in paragraphs [0038] to [0055] of Japanese patent laid-open No. 2012-211316 can be suitably employed, and the contents thereof are incorporated herein by reference.

(content)

The content of the specific fine particles in the composition of the present invention is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 2 to 10 parts by mass, based on 100 parts by mass of the diene rubber, from the viewpoint of further improving the effect of the present invention.

[ preparation method of rubber composition for tire ]

The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include a method of kneading the above components by a known method or apparatus (e.g., a banbury mixer, a kneader, a roll, etc.). When the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to mix the components other than sulfur or a vulcanization accelerator at a high temperature (preferably 100 to 160 ℃) and cool the mixture, and then mix the sulfur or the vulcanization accelerator.

The composition of the present invention may be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[ studless tire ]

The studless tire of the present invention is a studless tire manufactured using the composition of the present invention described above. Among them, a studless tire having a tread portion manufactured using the composition of the present invention is preferable.

Fig. 2 shows a schematic partial cross-sectional view of a studless tire showing an example of the embodiment of the studless tire according to the present invention, but the studless tire according to the present invention is not limited to the form shown in fig. 2.

In fig. 2, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion.

Further, a carcass layer 4 in which a fiber cord is embedded is mounted between the pair of left and right bead portions 1, and the end portion of the carcass layer 4 is folded back and rolled up from the inner side to the outer side of the tire around a bead core 5 and a bead filler 6.

Further, in the tread portion 3, a belt layer 7 is disposed over the circumference of the tire 1 on the outer side of the carcass layer 4.

Further, in the bead portion 1, a rim cushion 8 is disposed at a portion that contacts a rim.

Further, the tread portion 3 is formed by the composition of the present invention described above.

The studless tire of the present invention can be manufactured by a conventionally known method, for example. As the gas to be filled in the studless tire of the present invention, inert gas such as nitrogen, argon, helium or the like can be used in addition to air having a normal or adjusted oxygen partial pressure.