阅读说明：本技术 轮胎用橡胶组合物及无钉轮胎 (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 2019-03-11 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、以及使用了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是下述轮胎用橡胶组合物,其含有：二烯系橡胶100质量份；炭黑和/或白色填充剂30～100质量份；平均粒径为5～500μm的进行了三维交联的有机硅系微粒1～20质量份；非离子性表面活性剂0.1～10质量份；以及热膨胀性微胶囊1～20质量份。(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 is a rubber composition for a tire, containing: 100 parts by mass of a diene rubber; 30-100 parts by mass of carbon black and/or white filler; 1 to 20 parts by mass of three-dimensionally crosslinked silicone-based microparticles having an average particle diameter of 5 to 500 μm; 0.1-10 parts by mass of a nonionic surfactant; and 1 to 20 parts by mass of a thermally expandable microcapsule.)

1. A rubber composition for a tire, comprising:

100 parts by mass of a diene rubber;

30-100 parts by mass of carbon black and/or white filler;

1 to 20 parts by mass of three-dimensionally crosslinked silicone-based microparticles having an average particle diameter of 5 to 500 μm;

0.1-10 parts by mass of a nonionic surfactant; and

1 to 20 parts by mass of a thermally expandable microcapsule.

2. The rubber composition for a tire according to claim 1, wherein the diene rubber contains 30% by mass or more of at least 1 rubber selected from the group consisting of NR, which is a natural rubber, IR, which is an isoprene rubber, BR, which is a nitrile rubber, NBR, SBR, which is a styrene-isoprene rubber, SIR, SIBR, and derivatives of these rubbers.

3. The rubber composition for a tire according to claim 1 or 2, wherein the fine silicone particles are obtained by three-dimensionally crosslinking silicone in a liquid polymer containing a nonionic surfactant.

4. The rubber composition for a tire according to any one of claims 1 to 3, wherein the nonionic surfactant is a compound represented by the following formula (d),

in formula (d), R represents a hydrocarbon group, L represents a single bond or a 2-valent linking group, R¹Represents a polyalkyleneoxy group, R²Represents a hydrocarbon group, m and n each independently represent an integer of 1 or more; the R's present may be the same or different; l, R in the case where n is an integer of 2 or more¹And R²May be the same or different.

5. A studless tire comprising a tire tread portion produced using the rubber composition for a tire according to any one of claims 1 to 4.

Technical Field

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

Background

Conventionally, a rubber composition for a tire containing silicone microparticles for the purpose of improving the on-ice friction of a studless tire has been studied.

For example, patent document 1 discloses a rubber composition for a tire, which contains a diene rubber and silicone microparticles. Patent document 1 describes that the rubber composition for a tire is excellent in on-ice performance.

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, it is also required to achieve both wear resistance and abrasion resistance.

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 problems and found that the above problems can be solved by using a specific silicone-based fine particle and a nonionic surfactant in combination with a thermally expandable microcapsule at a specific amount ratio, and the present invention has been completed.

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

(1) A rubber composition for a tire, comprising:

100 parts by mass of a diene rubber;

30-100 parts by mass of carbon black and/or white filler;

1 to 20 parts by mass of three-dimensionally crosslinked silicone-based microparticles having an average particle diameter of 5 to 500 μm;

0.1-10 parts by mass of a nonionic surfactant; and

1 to 20 parts by mass of a thermally expandable microcapsule.

(2) The rubber composition for a tire according to the item (1), wherein the diene rubber contains 30% by mass or more of at least 1 rubber selected from the group consisting of 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), and derivatives of these rubbers.

(3) The rubber composition for a tire according to the item (1) or (2), wherein the silicone-based fine particles are obtained by three-dimensionally crosslinking silicone in a liquid polymer containing a nonionic surfactant.

(4) The rubber composition for a tire according to any one of the above (1) to (3), wherein the nonionic surfactant is a compound represented by the following formula (d).

(5) A studless tire comprising a tire tread portion produced using the rubber composition for a tire according to any one of the above (1) to (4).

ADVANTAGEOUS EFFECTS OF INVENTION

As described below, according to the present invention, 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 can be provided.

Drawings

Fig. 1 is a schematic partial cross-sectional view of an example of an embodiment of a studless tire according to 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 components are used in combination, the content of each 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 a diene rubber; 30-100 parts by mass of carbon black and/or white filler; 1 to 20 parts by mass of three-dimensionally crosslinked silicone-based microparticles having an average particle diameter of 5 to 500 μm; 0.1-10 parts by mass of a nonionic surfactant; and 1 to 20 parts by mass of a thermally expandable microcapsule.

It is considered that the composition of the present invention has such a constitution, and therefore the above-mentioned effects can be obtained. The reason for this is not clear, but is presumed to be as follows.

As described above, the composition of the present invention contains the heat-expandable microcapsule. Here, the above-mentioned thermally-expansible microcapsules have an effect of increasing the frictional force with the road surface by absorbing water on ice, but according to the study of the present inventors, it has been found that when only thermally-expansible microcapsules are blended, the motive force for water to permeate into the thermally-expansible microcapsules is small, and the water absorbing action of the thermally-expansible microcapsules is insufficient.

On the other hand, since the composition of the present invention uses the silicone-based fine particles and the nonionic surfactant in a specific amount ratio in combination in addition to the heat-expandable microcapsules, water on ice is efficiently induced into the rubber by the nonionic surfactant, and the rubber is complexly deformed during movement by the presence of the silicone-based fine particles, which becomes a motive force and water is rapidly absorbed into the heat-expandable microcapsules. As a result, it can be considered that the composition of the present invention exhibits extremely excellent on-ice performance. Further, it is considered that the rubber composition has high homogeneity and excellent abrasion resistance because the above components are blended in a specific amount ratio.

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

[ diene rubber ]

As described above, the composition of the present invention contains a diene rubber.

Specific examples of the diene rubber 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 rubbers.

The diene rubber preferably contains at least 1 of these rubbers in an 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, more preferably 40 to 60% by mass, for 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 more 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 further preferably 150,000 to 1,500,000, for the reason that the effect of the present invention is more excellent.

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

[ carbon Black and/or white Filler ]

As described above, the composition of the present invention contains carbon black and/or a white filler. The composition of the present invention preferably contains both carbon black and a white filler because the effect of the present invention is more excellent.

< carbon Black >

The carbon black is not particularly limited, and various grades of carbon black such as SAF-HS, SAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF-LS, FEF, GPF, SRF and the like can be used.

The nitrogen adsorption specific surface area (N) of the carbon black ₂SA), but is preferably 50 to 200m, because the effect of the present invention is more excellent²A concentration of 70 to 150m is more preferable²/g。

Here, the nitrogen adsorption specific surface area (N)₂SA) is a value according to JIS K6217-2: 2001 "section 2: determination of specific surface area め method-chunking adsorption method- point method (2 nd: determination of specific surface area-nitrogen adsorption method-single point method)' 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 the effect of the present invention is more excellent.

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, silica is preferable because the effect of the present invention is more excellent.

The specific surface area of Cetyl Trimethyl Ammonium Bromide (CTAB) adsorption of the silica is not particularly limited, but is preferably 100 to 400m for the reason that the effect of the present invention is more excellent²A concentration of 150 to 300m ²A 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: specific surface area determination め side-CTAB adsorption method (section 3: determination of specific surface area-CTAB adsorption method)' A value obtained by measuring the amount of CTAB adsorption onto the silica surface was measured.

< content >

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 30 to 100 parts by mass per 100 parts by mass of the diene rubber. Among them, the amount is more preferably 40 to 90 parts by mass, and still more preferably 45 to 80 parts by mass, for the reason that the effect of the present invention is more excellent.

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 more 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 ]

As described above, the composition of the present invention contains three-dimensionally crosslinked silicone-based microparticles (hereinafter, also referred to as "specific microparticles") having an average particle diameter of 5 to 500. mu.m.

< average particle diameter >

For the reason that the effect of the present invention is more excellent, the average particle diameter of the specific fine particles is preferably 5 to 100 μm, and more preferably 10 to 50 μm.

The average particle diameter is an average value of equivalent circle diameters measured by a laser microscope, and can be measured by, for example, a laser diffraction scattering particle size distribution measuring device LA-300 (manufactured by horiba, Ltd.), a laser microscope VK-8710 (manufactured by キーエンス, Ltd.), and the like.

The silicone-based fine particles are fine particles having a siloxane bond in the main chain skeleton, and for example, fine particles having no polyisoprene skeleton and crosslinked by a siloxane bond (by a terminal hydrolyzable silyl group) are not included.

< adaptive scheme 1 >

The specific fine particles are preferably three-dimensionally crosslinked silicone particles for the reason that the effect of the present invention is more excellent. The crosslinking is not particularly limited, but is preferably a condensation type or addition type, and more preferably a condensation type, because the effect of the present invention is more excellent.

(organic silicon)

The silicone is not particularly limited as long as it is a compound having an organopolysiloxane as a main chain, and specific examples thereof include polydimethylsiloxane, methyl hydrogenpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, raw dimethyl silicone rubber, raw methyl vinyl silicone rubber, raw methylphenyl silicone rubber, raw fluoro silicone rubber, and the like. Among these, polydimethylsiloxane is preferable because the effect of the present invention is more excellent.

Further, the silicone preferably has a reactive functional group for the reason that the effect of the present invention is more excellent. Specific examples of the reactive functional group include a hydroxyl group, a mercapto group, a silane functional group, an isocyanate group, a (meth) acryloyl group, an allyl group, a carboxyl group, an acid anhydride group, and an epoxy group.

Here, the silane functional group is also referred to as a so-called crosslinkable silyl group, and specific examples thereof include a hydrolyzable silyl group; a silanol group; functional groups obtained by substituting silanol groups with acetoxy derivatives, alkenyloxy (エノキシ -yl) derivatives, oximino derivatives, amine derivatives, and the like; and the like.

The reactive functional group is preferably a hydroxyl group, a silane functional group, a carboxyl group or an acid anhydride group, and more preferably a silane functional group (particularly a silanol group) because the effect of the present invention is more excellent.

Commercially available products of silicones having such reactive functional groups include, for example, both-terminal silanol-modified polydimethylsiloxane [ SS-10 (m: 336 in the formula), KF-9701 (m: 38 in the formula), X-21-5841 (m: 11 in the formula), both manufactured by shin-Etsu chemical Co., Ltd.), both-terminal carboxyl-modified polydimethylsiloxane (X-22-162C, manufactured by shin-Etsu chemical Co., Ltd.) represented by the following formula (2).

The silicone preferably has the reactive functional group at least at the end of the main chain of the silicone, for the reason that the effect of the present invention is more excellent, and preferably has 1.5 or more, and more preferably 2 or more, for the reason that the effect of the present invention is more excellent when the main chain is linear. On the other hand, in the case of a branched main chain, it is preferable that the number of the main chain is 3 or more because the effect of the present invention is more excellent.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the silicone are not particularly limited, but are preferably 1,000 to 100,000, more preferably 3,000 to 60,000, because the effect of the present invention is more excellent.

(three-dimensional crosslinking)

Examples of the method of three-dimensionally crosslinking the silicone include a method of vulcanizing with a vulcanizing agent, a method of three-dimensionally crosslinking with the reactive functional group, and the like.

Specifically, a method of vulcanizing the rubber composition with a vulcanizing agent includes a method of vulcanizing the rubber composition with an organic peroxide by using a raw silicone rubber as a silicone.

Further, as a method for performing three-dimensional crosslinking by using a reactive functional group, specifically, a method for performing three-dimensional crosslinking by reacting a silicone having a reactive functional group with at least 1 component selected from the group consisting of water, a catalyst, a polymerization initiator, and a compound having a functional group reactive with the reactive functional group, and the like can be cited.

The method of three-dimensionally crosslinking the silicone is not limited to these methods, and examples thereof include curing with an electron beam; neutrons and protons produced from deuterium accelerated by a cyclotron; gamma rays from cobalt 60 are X-rays from the target; and the like.

Specific examples of the organic peroxide include benzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, dicumyl peroxide, 2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane, p-chlorobenzoyl peroxide, di-t-butyl peroxide, t-butyl perbenzoate, and the like, and 1 kind of the organic peroxide may be used alone or 2 or more kinds may be used in combination depending on the temperature, the use conditions, and the like.

The water can be suitably used when the silicone has a hydrolyzable silyl group, an isocyanate group, or an acid anhydride group as a reactive functional group.

Examples of the catalyst include a condensation catalyst.

Specific examples of the condensation catalyst include dibutyltin dilaurate, dibutyltin dioleate, dibutyltin diacetate, tetrabutyl titanate, stannous octoate, and octyltin compounds.

The polymerization initiator can be suitably used in the case where the silicone has a (meth) acryloyl group or a mercapto group and an unsaturated double bond, and specific examples thereof include radical polymerization initiators such as azobisisobutyronitrile and benzoyl peroxide.

In addition, use is made of such a polymerizationThe three-dimensional crosslinking of the initiator can be carried out by addition reaction using a platinum catalyst in addition to ultraviolet curing

Cationic polymerization of salt catalysts.

Examples of the compound having a functional group reactive with the reactive functional group include a condensation type curing agent and a hydrosilane compound.

Examples of the condensation-type curing agent include acetic acid-type curing agents that undergo condensation reaction by removing acetic acid, and in addition, alcohol-type, oxime-type, amine-type, amide-type, aminooxy-type, acetone-type, hydroxylamine-type, hydrogen-type, dehydration-type curing agents, and the like, and these can be used as appropriate.

Among them, preferred is an alcohol-type curing agent which undergoes a condensation reaction by dealcoholization, and specific examples thereof include an alkoxysilane (e.g., vinyltrimethoxysilane), a methylsilicate oligomer, and an organosiloxane oligomer.

The hydrosilane compound is a compound having an SiH group, and can be suitably used when the organosilicon has an allyl group as a reactive functional group.

Specific examples of the hydrosilane compound include 1,1,3, 3-tetramethyldisiloxane, 1,3,5, 7-tetramethyltetracyclosiloxane, 1,3,5,7, 8-pentamethylpentacyclosiloxane, and the like.

In addition, in the case of using the above hydrosilane compound, a catalyst (for example, a metal complex catalyst selected from group VIII transition metal elements such as platinum, rhodium, cobalt, palladium, and nickel) that promotes a reaction with an organosilicon having an allyl group can be used.

< adaptive scheme 2 >

As described above, the specific fine particles are preferably three-dimensionally crosslinked silicone particles for the reason that the effects of the present invention are more excellent (embodiment 1 is suitable). Among these, for the reason that the effect of the present invention is more excellent, a three-dimensionally crosslinked silicone is more preferable in a liquid polymer containing a nonionic surfactant (preferable embodiment 2).

When a liquid polymer containing a nonionic surfactant and silicone three-dimensionally crosslinked is used as the specific fine particles, the specific fine particles exhibit more excellent on-ice performance and abrasion resistance.

The reason for obtaining such an effect is not clear, but it is considered that homogeneity of the crosslinked structure is improved by three-dimensionally crosslinking the silicone in the coexistence of the nonionic surfactant. However, it is impossible or completely impractical to specify its specific structure.

In suitable scheme 2, regarding silicone and three-dimensional crosslinking, the same as in suitable scheme 1.

(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 polyisoprene 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, and still more preferably 10,000 to 30,000, because the effect of the present invention is more excellent.

(nonionic surfactant)

Specific examples and suitable embodiments of the nonionic surfactant are the same as those of the nonionic surfactant described later.

In embodiment 2, the content of the nonionic surfactant in the liquid polymer is not particularly limited, but is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, and still more preferably 3 to 10% by mass, because the effect of the present invention is more excellent.

< content >

In the composition of the present invention, the content of the specific fine particles is 1 to 20 parts by mass per 100 parts by mass of the diene rubber. Among these, 2 to 15 parts by mass are preferable, and 3 to 10 parts by mass are more preferable, because the effect of the present invention is more excellent.

[ nonionic surfactant ]

As described above, the composition of the present invention contains a nonionic surfactant.

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), polyoxyethylene-polyoxypropylene block polymers, silicone foam stabilizers, and the like. Among these, the silicone foam stabilizer is preferable, and the compound represented by the following formula (d) is more preferable, because the effect of the present invention is more excellent.

< specific foam stabilizer >

As described above, the nonionic surfactant is preferably a compound represented by the following formula (d) (hereinafter, also referred to as a "specific foam stabilizer") because the effect of the present invention is more excellent.

In the formula (d), R represents a hydrocarbon group, L represents a single bond or a 2-valent linking group, R¹Represents a polyalkyleneoxy group (- (R)¹¹O)_a+b-：R¹¹Represents an alkylene group, and a + b represents an integer of 2 or more. Multiple existence of R¹¹May be the same or different. ) R is²Represents a hydrocarbon group, and m and n each independently represent an integer of 1 or more.

The R's present in a plurality may be the same or different. When n is an integer of 2 or more, L, R in the presence of a plurality¹And R²May be the same or different.

As described above, in the above formula (d), R represents a hydrocarbon group.

Examples of the hydrocarbon group include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a combination thereof. The aliphatic hydrocarbon group may be linear, branched or cyclic. Specific examples of the aliphatic hydrocarbon group include a linear or branched alkyl group (preferably having 1 to 10 carbon atoms), a linear or branched alkenyl group (preferably having 2 to 10 carbon atoms), a linear or branched alkynyl group (preferably having 2 to 10 carbon atoms), and the like. Examples of the aromatic hydrocarbon group include an aryl group and a naphthyl group. Examples of the aryl group include a phenyl group, a tolyl group, and a xylyl group. Among them, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 3 carbon atoms) is preferable because the effect of the present invention is more excellent.

As described above, in the formula (d), L represents a single bond or a 2-valent linking group.

The 2-valent linking group includes a 2-valent aliphatic hydrocarbon group (e.g., alkylene group, preferably having 1 to 8 carbon atoms), a 2-valent aromatic hydrocarbon group (e.g., arylene group, preferably having 6 to 12 carbon atoms), -O-, -S-, -SO₂-, -N (R) - (R: alkyl), -CO-, -NH-, -COO-, -CONH-, or a combination thereof (for example, alkyleneoxy, alkyleneoxycarbonyl, alkylenecarbonyloxy, etc.), and the like.

As described above, in the above formula (d), R¹Represents a polyalkyleneoxy group.

The above-mentioned polyalkyleneoxy group is represented by- (R)¹¹O)_a+b-represents.

Here, R¹¹Represents an alkylene group (preferably having 1 to 5 carbon atoms). Further, a + b represents an integer of 2 or more. Multiple existence of R¹¹May be the same or different.

The polyalkyleneoxy group is preferably- (CH) for the reason that the effect of the present invention is more excellent₂CH₂O)_a-(CH₂CH(CH₃)O)_b-a group as shown.

Here, a and b each independently represent an integer of 0 or more. Wherein a + b represents an integer of 2 or more. In addition, a and b each represent (CH) present in the group₂CH₂O) andin the radical (CH)₂CH(CH₃) Total number of O), (CH)₂CH₂O) and (CH)₂CH(CH₃) O) is arbitrary.

As described above, in the above formula (d), R²Represents a hydrocarbon group. Specific examples of the hydrocarbon group are as described above.

As described above, m and n each independently represent an integer of 1 or more.

< content >

The content of the nonionic surfactant is 0.1 to 10 parts by mass per 100 parts by mass of the diene rubber. Among these, the amount is more preferably 0.5 to 8 parts by mass, and still more preferably 1 to 5 parts by mass, for the reason that the effect of the present invention is more excellent.

[ Heat-Expandable microcapsules ]

As described above, the composition of the present invention contains the heat-expandable microcapsule.

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

The particle size of the thermally expandable microcapsules before expansion is preferably 5 to 300 μm, more preferably 10 to 200 μm.

As the thermoplastic resin, for example, a polymer of (meth) acrylonitrile and/or a copolymer having a high (meth) acrylonitrile content is suitably 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 is contained in the thermally expandable microcapsule and is gasified or expanded by heat to generate a gas 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 a solid such as azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, a tosylhydrazide derivative, an aromatic succinyl hydrazide derivative, and the like.

As such heat-expandable microcapsules, commercially available ones can be used, and they are available, for example, under the trade names "エクスパンセル 091 DU-80", "エクスパンセル 092 DU-120" manufactured by EXPANCEL corporation of スウェーデン, under the 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" manufactured by Songbird grease pharmacy.

In the composition of the present invention, the content of the thermally expandable microcapsule is 1 to 20 parts by mass per 100 parts by mass of the diene rubber. Among these, 2 to 15 parts by mass are preferable, and 3 to 10 parts by mass are more preferable, because the effect of the present invention is more excellent.

[ ratio of amounts of ingredients ]

In the composition of the present invention, the ratio of the content of the nonionic surfactant to the content of the specific fine particles (content of the nonionic surfactant/content of the specific fine particles) is preferably 1 to 100% by mass, more preferably 2 to 20% by mass, and still more preferably 5 to 15% by mass, for the reason that the effect of the present invention is more excellent.

In the composition of the present invention, the proportion of the content of the heat-expandable microcapsule to the content of the specific fine particles (content of the heat-expandable microcapsule/content of the specific fine particles) is preferably 50 to 200% by mass, more preferably 80 to 120% by mass, and still more preferably 90 to 110% by mass, for the reason that the effect of the present invention is more excellent.

In the composition of the present invention, the ratio of the total content of the nonionic surfactant and the heat-expandable microcapsules to the content of the specific fine particles (the total content of the nonionic surfactant and the heat-expandable microcapsules/the content of the specific fine particles) is preferably 50 to 500% by mass, more preferably 80 to 200% by mass, still more preferably 90 to 150% by mass, and particularly preferably 105 to 115% by mass, because the effect of the present invention is more excellent.

[ 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 silane coupling agents, terpene resins (preferably aromatic modified terpene resins), zinc oxide (zinc oxide), stearic acid, antioxidants, waxes, processing aids, process oils, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), and vulcanization accelerators.

[ 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 tire tread portion manufactured using the composition of the present invention is preferable.

Fig. 1 shows a schematic partial cross-sectional view of a studless tire showing an example of an embodiment of the studless tire of the present invention, but the studless tire of the present invention is not limited to the form shown in fig. 1.

In fig. 1, 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 tire 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 tire tread portion 3 is formed using the composition of the present invention.

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 normal air or air with an adjusted oxygen partial pressure.