JP2016056248A - Rubber composition for tire and studless tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire, allowing for production of a studless tire excellent both in on-ice performance and long term stability, and a studless tire employing the same.SOLUTION: The rubber composition for a tire is provided which contains: (A) a diene rubber; (B) a carbon black and/or a white filler; (C) a crosslinkable oligomer incompatible with the diene rubber (A) or a polymer; and (D) a foaming component obtained by mixing a chemical foaming agent (d1) and a foaming assistant (d2) at a mass ratio (d1/d2) of 0.3 to 2.0 (D), and in which the content of the carbon black and/or the white filler (B) is 30 to 100 pts.mass based on 100 pts.maass of the diene rubber (A), the content of total of the crosslinkable oligomer or the polymer (C) and the foaming component (D) is 0.1 to 30 pts.mass based on 100 pts.mass of the diene rubber (D) and the mass ratio of the crosslinkable oligomer or the polymer (C) and the foaming component (D) (C/D) is 0.80 to 3.0.SELECTED DRAWING: None

Description

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

  For the purpose of maintaining and improving the flexibility and friction on ice of a studless tire, it is known to add various plasticizers to the tire rubber composition.

For example, Patent Document 1 discloses that (B) carbon black with respect to 100 parts by weight of at least one rubber selected from (A) natural rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, polyisoprene rubber and butyl rubber. And / or 30 to 80 parts by weight of silica, and (C) a compound having a polyisobutylene main chain and at least one alkoxysilyl group and / or a main chain of the formula —R ¹ —O— (wherein R ¹ is , A tread for studless tires comprising 3 to 50 parts by weight of a compound having at least one alkoxysilyl group in a polyether system having a repeating unit represented by a divalent hydrocarbon group having 1 to 8 carbon atoms) Rubber composition "is described ([Claim 1]).

Japanese Patent Laid-Open No. 11-093110

  However, when the present inventors examined the tread rubber composition for studless tires described in Patent Document 1, there is room for improvement in performance on ice, and over a long period (for example, 3 to 4 seasons). It has become clear that there is room for improvement in performance stability (hereinafter also referred to as “long-term stability”).

  Then, this invention makes it a subject to provide the rubber composition for tires which can produce the studless tire excellent in both on-ice performance and long-term stability, and a studless tire using the same.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that performance on ice can be improved by using a rubber composition in which a predetermined crosslinkable oligomer or polymer and a predetermined foaming component are blended at a specific mass ratio. The inventors have found that a studless tire excellent in both long-term stability can be produced, and completed the present invention.
That is, the present inventors have found that the above problem can be solved by the following configuration.

[1] Diene rubber (A),
Carbon black and / or white filler (B);
A crosslinkable oligomer or polymer (C) that is incompatible with the diene rubber (A);
A foaming component (D) in which a chemical foaming agent (d1) and a foaming aid (d2) are mixed at a mass ratio (d1 / d2) of 0.3 to 2.0, and
Content of the said carbon black and / or white filler (B) is 30-100 mass parts with respect to 100 mass parts of said diene rubber (A),
The total content of the crosslinkable oligomer or polymer (C) and the foaming component (D) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber (A),
The rubber composition for tires whose mass ratio (C / D) of the said crosslinkable oligomer or polymer (C) and the said foaming component (D) is 0.80-3.0.
[2] The rubber composition for tires according to [1], wherein the crosslinkable oligomer or polymer (C) and the foaming component (D) are contained as a mixture obtained by mixing them in advance.
[3] The crosslinkable oligomer or polymer (C) and the foaming component (D) use at least one catalyst selected from the group consisting of an acid catalyst, an alkali catalyst, a metal catalyst, and an amine catalyst as the mixture. The rubber composition for tires according to [2], which is contained as a cured product cured in this manner.
[4] The tire rubber composition according to any one of [1] to [3], wherein the chemical foaming agent (d1) is azodicarbonamide and / or dinitrosopentastyrenetetramine.
[5] The tire rubber composition according to any one of [1] to [4], further comprising a thermally expandable microcapsule.
[6] A studless tire using the tire rubber composition according to any one of [1] to [5] for a tire tread.

  As shown below, according to the present invention, it is possible to provide a tire rubber composition capable of producing a studless tire excellent in both on-ice performance and long-term stability, and a studless tire using the same. .

It is a typical fragmentary sectional view of the tire showing an example of the embodiment of the studless tire of the present invention.

[Rubber composition for tire]
The tire rubber composition of the present invention comprises a diene rubber (A), a carbon black and / or white filler (B), and a crosslinkable oligomer or polymer (C) that is incompatible with the diene rubber (A). And a foaming component (D) obtained by mixing a chemical foaming agent (d1) and a foaming aid (d2) at a mass ratio (d1 / d2) of 0.3 to 2.0.
Moreover, content of the said carbon black and / or white filler (B) is 30-100 mass parts with respect to 100 mass parts of said diene rubber (A).
Furthermore, the total content of the crosslinkable oligomer or polymer (C) and the foaming component (D) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber (A). The mass ratio (C / D) between the functional oligomer or polymer (C) and the foaming component (D) is 0.80 to 3.0.

In the present invention, as described above, the crosslinkable oligomer or polymer (C), the chemical foaming agent (d1) and the foaming aid (d2) are mixed at a mass ratio (d1 / d2) of 0.3 to 2.0. By blending the foaming component (D) at a specific mass ratio, the on-ice performance and long-term stability of a studless tire using the tire rubber composition of the present invention for a tire tread are both improved.
This is not clear in detail, but is estimated to be as follows.
That is, by blending the crosslinkable oligomer or polymer (C) and the foaming component (D) at a specific mass ratio, a part of the crosslinkable oligomer or polymer (C) is foamed during vulcanization, A soft domain incompatible with the diene rubber (A) after vulcanization is formed. And since this domain is foamed, it becomes possible to drain the water film on the road surface on ice, and the adhesion force to the road surface of a domain part improves, and it is thought that the friction force on ice improves. In addition, since this domain can maintain its softness even at a low temperature and after a lapse of time from the start of use, it is considered that long-term performance on ice can be maintained.
Below, each component which the rubber composition for tires of this invention contains is demonstrated in detail.

<Diene rubber (A)>
The diene rubber (A) contained in the tire rubber composition of the present invention is not particularly limited as long as it has a double bond in the main chain, and specific examples thereof include natural rubber (NR) and isoprene rubber. (IR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), and the like. These may be used alone or in combination of two or more.
The diene rubber (A) is a derivative in which the terminal or side chain of each rubber is modified (modified) with an amino group, amide group, silyl group, alkoxy group, carboxy group, hydroxy group, epoxy group or the like. It may be.
Among these, NR, BR, and SBR are preferably used, and NR and BR are more preferably used in combination, because the performance on ice of the studless tire becomes better.

In the present invention, the average glass transition temperature of the diene rubber (A) is −50 ° C. or less because the hardness of the studless tire can be kept low even at low temperatures and the performance on ice is better. Is preferred.
Here, the glass transition temperature is a value measured at a heating rate of 10 ° C./min according to ASTM D3418-82 using a differential thermal analyzer (DSC) manufactured by DuPont.
The average glass transition temperature is an average value of the glass transition temperature. When only one diene rubber is used, the glass transition temperature of the diene rubber is used. When two or more diene rubbers are used in combination, Means the glass transition temperature of the entire diene rubber (mixture of each diene rubber), and can be calculated as an average value from the glass transition temperature of each diene rubber and the blending ratio of each diene rubber.

  In the present invention, 20 mass% or more of the diene rubber (A) is preferably NR, and more preferably 40 mass% or more is NR because the strength of the studless tire is good. .

<Carbon black and / or white filler (B)>
The rubber composition for tires of the present invention contains carbon black and / or a white filler (B).

(Carbon black)
Specific examples of the carbon black include furnace carbon blacks such as SAF, ISAF, HAF, FEF, GPE, and SRF. These may be used alone or in combination of two or more. May be.
In addition, the carbon black preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 10 to 300 m ² / g from the viewpoint of processability when mixing the rubber composition, reinforcement of the studless tire, and the like. more preferably from 200 m ² / g, to improve the wet performance of the studless tire, for the reasons ice performance becomes better, is preferably from 50 to 150 m ² / g, in 70~130m ² / g More preferably.
Here, N ₂ SA is a value obtained by measuring the amount of nitrogen adsorbed on the carbon black surface in accordance with JIS K 6217-2: 2001 “Part 2: Determination of specific surface area—nitrogen adsorption method—single point method”. .

(White filler)
Specific examples of the white filler include silica, calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide, calcium sulfate, and the like. Or two or more of them may be used in combination.
Among these, silica is preferable because the performance on ice of the studless tire becomes better.

Specific examples of silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like, and these may be used alone. Two or more kinds may be used in combination.
Among these, wet silica is preferable because the performance on ice of the studless tire is further improved and the wear resistance is further improved.

The silica preferably has a CTAB adsorption specific surface area of 50 to 300 m ² / g, more preferably 70 to 250 m ² / g, because the wet performance and rolling resistance of the studless tire are good. More preferably, it is -200 m < ² > / g.
Here, the CTAB adsorption specific surface area was determined by measuring the adsorption amount of n-hexadecyltrimethylammonium bromide on the silica surface according to JIS K6217-3: 2001 “Part 3: Determination of specific surface area—CTAB adsorption method”. Value.

In this invention, content of the said carbon black and / or white filler (B) is 30-100 mass parts with respect to 100 mass parts of said diene rubber (A), and is 40-90 mass parts. Is preferable, and it is more preferable that it is 45-80 mass parts.
Here, the content of carbon black and / or white filler (B) refers to the content of one of carbon black and white filler when containing only one of carbon black and white filler. When all the fillers are contained, the total content of carbon black and white filler is meant.
Moreover, when using the said carbon black and the said white filler together, it is preferable that content of the said white filler is 5-85 mass parts with respect to 100 mass parts of the said diene rubber (A), 15 More preferably, it is -75 mass parts.

<Crosslinkable oligomer or polymer (C)>
The crosslinkable oligomer or polymer (C) contained in the tire rubber composition of the present invention is not particularly limited as long as it is not compatible with the diene rubber (A) and has crosslinkability.
Here, “(incompatible with the diene rubber (A))” does not mean that it is incompatible with all the rubber components included in the diene rubber (A). The specific components used for the rubber (A) and the crosslinkable oligomer or polymer (C) are incompatible with each other.

  Examples of the crosslinkable oligomer or polymer (C) include polyether-based, polyester-based, polyolefin-based, polycarbonate-based, aliphatic-based, saturated hydrocarbon-based, acrylic-based, urethane-based, plant-based or siloxane-based heavy polymers. Examples thereof include a polymer or a copolymer.

  Among these, for the reason that the performance on ice of the studless tire becomes better, the crosslinkable oligomer or polymer (C) is a polyether-based, polyester-based, polyolefin-based, polycarbonate-based, acrylic-based, urethane-based or plant-derived A polymer or copolymer of the type is preferable, and a polymer or copolymer of the polyether type is more preferable.

Here, examples of the polyether polymer or copolymer include polyethylene glycol, polypropylene glycol (PPG), polypropylene triol, ethylene oxide / propylene oxide copolymer, polytetramethylene ether glycol (PTMEG), and sorbitol. Based polyols and the like.
Examples of the polyester-based polymer or copolymer include low-molecular polyhydric alcohols (for example, ethylene glycol, diethylene glycol, propylene glycol) and polybasic carboxylic acids (for example, adipic acid, sebacic acid, Condensates with terephthalic acid, isophthalic acid and the like) (condensed polyester polyols); lactone polyols, and the like.
Examples of the polyolefin polymer or copolymer include polyethylene, polypropylene, ethylene propylene copolymer (EPR, EPDM), polybutylene, polyisobutylene, hydrogenated polybutadiene, and the like.
Examples of the polycarbonate-based polymer or copolymer include esters of polyol compounds (for example, 1,6-hexanediol, 1,4-butanediol, 1,5-pentanediol, etc.) and dialkyl carbonate. Examples thereof include those obtained by exchange reaction.
Examples of the acrylic polymer or copolymer include acrylic polyols; acrylate homopolymers such as acrylates, methyl acrylates, ethyl acrylates, butyl acrylates, 2-ethylhexyl acrylates; and combinations of two or more of these acrylates. Acrylate copolymer; and the like.
Examples of the urethane polymer or copolymer include a polymer obtained by reacting a hydroxyl group of a polyol compound (for example, a polycarbonate polyol) with an isocyanate group of a polyisocyanate compound described later.
Examples of the plant-derived polymer or copolymer include vegetable oils such as castor oil and soybean oil; various elastomers derived from polyester polyols modified with polylactic acid, and the like.

In the present invention, the crosslinkable oligomer or polymer (C) has a hydroxyl group, a silane functional group, an isocyanate group, and a (meth) acryloyl group because the performance on the ice of the tire becomes better by crosslinking between molecules. It preferably has at least one reactive functional group selected from the group consisting of an allyl group, a carboxy group, an acid anhydride group and an epoxy group.
Here, the “silane functional group” is also called a so-called crosslinkable silyl group, and specific examples thereof include hydrolyzable silyl group; silanol group; silanol group as acetoxy group derivative, enoxy group derivative, oxime group derivative. , Functional groups substituted with amine derivatives, and the like.
The “(meth) acryloyl group” is a comprehensive expression representing an acryloyl group or a methacryloyl group.

  Among these functional groups, the above-mentioned crosslinkable oligomer or polymer (C) is appropriately cross-linked at the time of rubber processing, the tire performance on ice is further improved, and the long-term stability is also improved. It preferably has an isocyanate group, an acid anhydride group or an epoxy group, and more preferably has a hydrolyzable silyl group or an isocyanate group.

Here, specific examples of the hydrolyzable silyl group include an alkoxysilyl group, an alkenyloxysilyl group, an acyloxysilyl group, an aminosilyl group, an aminooxysilyl group, an oximesilyl group, and an amidosilyl group. It is done.
Among these, an alkoxysilyl group is preferable because of a good balance between hydrolyzability and storage stability. Specifically, an alkoxysilyl group represented by the following formula (1) is preferable. More preferred are a methoxysilyl group and an ethoxysilyl group.

(In the formula, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a represents an integer of 1 to 3. a is 2 or 3) In this case, the plurality of R ¹ may be the same or different, and when a is 1, the plurality of R ¹ may be the same or different.)

Moreover, the said isocyanate group is an isocyanate group which remains when the hydroxyl group of a polyol compound (for example, polycarbonate-type polyol etc.) and the isocyanate group of a polyisocyanate compound are made to react.
The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. Specific examples thereof include TDI (for example, 2,4-tolylene diisocyanate (2,4-TDI). ), 2,6-tolylene diisocyanate (2,6-TDI)), MDI (for example, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4 ' -MDI)), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), Triphenylme Aromatic polyisocyanates such as polytriisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate (NBDI); transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis (isocyanatemethyl) cyclohexane (H ₆ XDI), alicyclic polyisocyanates such as dicyclohexylmethane diisocyanate (H ₁₂ MDI); these carbodiimide-modified polyisocyanates; these isocyanurate-modified polyisocyanates; It is done.

  In the present invention, the reactive functional group is preferably at least at the end of the main chain of the crosslinkable oligomer or polymer (C), and when the main chain is linear, 1.5 is present. It is preferable to have the above, and it is more preferable to have two or more. On the other hand, when the main chain is branched, it is preferably 3 or more.

In the present invention, the weight-average molecular weight or number-average molecular weight of the crosslinkable oligomer or polymer (C) improves dispersibility in the diene rubber (A) and kneading processability of the rubber composition. It is preferably 300 to 30000, and preferably 500 to 25000, because the particle size and shape can be easily adjusted when the fine particles (D) described later are prepared in the crosslinkable oligomer or polymer (C). Is more preferable, and it is still more preferable that it is 2000-20000.
Here, the weight average molecular weight and the number average molecular weight are both measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

  Furthermore, in this invention, content of the said crosslinkable oligomer or polymer (C) is 0 with respect to 100 mass parts of said diene rubber (A) with the total content with the foaming component (D) mentioned later. Although it is 1-30 mass parts, and if mass ratio (C / D) with the foaming component (D) mentioned later is 0.80-3.0, it will not specifically limit, The said diene rubber (A ) It is preferably 0.3 to 28 parts by mass, more preferably 0.5 to 25 parts by mass with respect to 100 parts by mass.

<Foaming component (D)>
The rubber composition for tires of this invention contains the foaming component (D) which mixed the chemical foaming agent (d1) and the foaming adjuvant (d2) by mass ratio (d1 / d2) 0.3-2.0.

(Chemical foaming agent (d1))
The chemical foaming agent (d1) is a chemical reaction type organic foaming agent, and specific examples thereof include azodicarbonamide (ADCA), dinitrosopentamethylenetetraamine (DPT), dinitrosopentastyrenetetramine, Oxybisbenzenesulfonyl hydrazide (OBSH), benzenesulfonyl hydrazide derivatives, ammonium bicarbonate generating carbon dioxide, ammonium carbonate, sodium bicarbonate, toluenesulfonyl hydrazide generating nitrogen, P-toluenesulfonyl semicarbazide, nitrososulfonylazo compound, N , N′-dimethyl-N, N′-dinitrosophthalamide, P, P′-oxy-bis (benzenesulfonyl semicarbazide), etc., may be used alone or in combination of two or more. Also good.

  Of these, azodicarbonamide (ADCA) and dinitrosopentamethylenetetraamine (DPT) are preferable, and azodicarbonamide (ADCA) is more preferable because of excellent processability during production.

(Foaming aid (d2))
Specific examples of the foaming aid (d2) include urea foaming aids (eg, urea); metal oxide foaming aids (eg, zinc stearate, zinc benzenesulfinate, zinc oxide) );

(Mass ratio)
The mass ratio (d1 / d2) of the chemical foaming agent (d1) and the foaming aid (d2) described above in the foaming component (D) is 0.3 to 2.0, and 0.6 to 1.9. It is preferable that it is 1.0 to 1.7.

(Preparation method)
The method for preparing the foaming component (D) is not particularly limited. For example, the chemical foaming agent (d1) and the foaming aid (d2) described above are used in the above-described mass ratio, and a known method and apparatus (for example, a Banbury mixer, A kneading method using a kneader or a roll).

  In this invention, content of the said foaming component (D) is 0.1 content with respect to 100 mass parts of said diene rubber (A), and total content with the crosslinkable oligomer or polymer (C) mentioned above. Although it is -30 mass parts, and if mass ratio (C / D) with the crosslinkable oligomer or polymer (C) mentioned above is 0.80-3.0, it will not specifically limit, The said diene rubber ( A) It is preferable that it is 2-20 mass parts with respect to 100 mass parts, and it is more preferable that it is 3-15 mass parts mass part.

In the present invention, the total content of the above-mentioned crosslinkable oligomer or polymer (C) and foaming component (D) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber (A). It is preferable that it is 5-25 mass parts, and it is more preferable that it is 10-20 mass parts.
Moreover, mass ratio (C / D) of the crosslinking | crosslinked oligomer or polymer (C) mentioned above and a foaming component (D) is 0.80-3.0, and it is 1.0-2.0. Preferably, it is 1.0 to 1.8.

<Mixture>
In the present invention, the crosslinkable oligomer or polymer (C) and the foaming component (D) are composed of the above-mentioned crosslinkable oligomer or polymer (C) and the foaming component (D) for the reason of good wear resistance. It is preferable to make it contain as a mixture previously mixed by the mass ratio mentioned above.
In addition, the preparation method of the said mixture is not specifically limited, For example, it is a well-known method and apparatus (for example, a Banbury mixer, a kneader) by the mass ratio which mentioned above crosslinkable oligomer or polymer (C) and foaming component (D). And a kneading method using a roll, etc.).

<Hardened product>
In the present invention, the crosslinkable oligomer or polymer (C) and the foaming component (D) can increase the probability of foaming in the crosslinkable oligomer or polymer (C). It is preferable to contain it as a cured product cured with at least one catalyst selected from the group consisting of an acid catalyst, an alkali catalyst, a metal catalyst and an amine catalyst.
Among these, a method of curing using an acid catalyst or a metal catalyst is preferable because of high curing efficiency.

(Acid catalyst)
Specific examples of the acid catalyst include, for example, lactic acid, phthalic acid, lauric acid, oleic acid, linoleic acid, linolenic acid, naphthenic acid, octenoic acid, octylic acid (2-ethylhexanoic acid), formic acid, Examples include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, benzoic acid, oxalic acid, malic acid, citric acid, and the like. In addition, two or more kinds may be used in combination.
In the present invention, from the viewpoint of acidity and dispersibility, it is preferable to use an acid that is liquid at room temperature, and more specifically, lactic acid and formic acid are more preferable.

(Metal catalyst)
Examples of the metal catalyst include organometallic compounds such as tin octylate, alkali metal alcoholates, and the like.
Specifically, tin carboxylates such as dimethyltin dilaurate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, tin octylate and tin naphthenate; titanates such as tetrabutyl titanate and tetrapropyl titanate; aluminum trisacetyl Organoaluminum compounds such as acetonate, aluminum trisethylacetoacetate, diisopropoxyaluminum ethylacetoacetate; Chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; Octanes such as lead octoate and bismuth octoate Acid metal salt; and the like.
In the present invention, tin carboxylates are more preferably used as the metal catalyst from the viewpoint of acidity.

<Thermal expandable microcapsules>
The rubber composition for tires of the present invention contains thermally expandable microcapsules composed of thermoplastic resin particles encapsulating a substance that vaporizes or expands by heat to generate gas because the performance on ice of the tire becomes better. It is preferable to do this.
Here, the heat-expandable microcapsule is heated at a temperature equal to or higher than the vaporization or expansion start temperature of the substance (for example, 140 to 190 ° C., preferably 150 to 180 ° C.). It becomes a microcapsule in which a gas is enclosed in a shell.
The particle size of the thermally expandable microcapsule is not particularly limited, but is preferably 5 to 300 μm and more preferably 10 to 200 μm before expansion.
Such heat-expandable microcapsules include, for example, trade names “Expancel 091DU-80” and “Expancel 092DU-120” manufactured by EXPANCEL, Sweden, and trade names “Matsumoto Micros, manufactured by Matsumoto Yushi Seiyaku Co., Ltd. Available as “Fair F-85”, “Matsumoto Microsphere F-100” or the like.

  In the present invention, the shell material of the above-mentioned thermally expandable microcapsule is a monomer whose main component is a nitrile monomer (I) and has an unsaturated double bond and a carboxyl group in the molecule. Body (II), monomer (III) having two or more polymerizable double bonds, and monomer (IV) copolymerizable with the above monomer to adjust the expansion characteristics as necessary It is comprised from the thermoplastic resin polymerized from.

Specific examples of the nitrile monomer (I) include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile, and mixtures thereof.
Of these, acrylonitrile and / or methacrylonitrile are preferred.
The copolymerization ratio of the nitrile monomer (I) is preferably 35 to 95% by mass, and more preferably 45 to 90% by weight.

Specific examples of the monomer (II) having an unsaturated double bond and a carboxyl group in the molecule include, for example, acrylic acid (AA), methacrylic acid (MAA), itaconic acid, styrenesulfonic acid or sodium salt. , Maleic acid, fumaric acid, citraconic acid, and mixtures thereof.
The copolymerization ratio of the monomer (II) is preferably 4 to 60% by mass, and more preferably 10 to 50% by mass. When the copolymerization ratio of the monomer (II) is 4% by weight or more, the expandability can be sufficiently maintained even in a high temperature region.

Specific examples of the monomer (III) having two or more polymerizable double bonds include, for example, aromatic divinyl compounds (for example, divinylbenzene, divinylnaphthalene, etc.), allyl methacrylate, triacryl formal, triallyl isocyanate. , Ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, weight Polyethylene glycol (PEG # 200) di (meth) acrylate having an average molecular weight of 200, polyethylene glycol (PEG # 400) di (meth) acrylate having a weight average molecular weight of 400, 1,6-hexanediol (meth) acrylate, Trimethylolpropane trimethacrylate, and mixtures thereof and the like.
The copolymerization ratio of the monomer (III) is preferably 0.05 to 5% by mass, and more preferably 0.2 to 3% by mass. When the copolymerization ratio of the monomer (III) is within this range, the expandability can be sufficiently maintained even in a high temperature region.

Specific examples of the copolymerizable monomer (IV) that can be used as needed include, for example, vinylidene chloride, vinyl acetate, methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl. (Meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid ester such as t-butyl (meth) acrylate, styrene, styrenesulfonic acid or its sodium salt, styrene monomer such as α-methylstyrene, chlorostyrene, acrylamide , Substituted acrylamide, methacrylamide, substituted methacrylamide and the like.
Monomer (IV) is an optional component, and when it is added, the copolymerization ratio is preferably 0.05 to 20% by mass, and more preferably 1 to 15% by weight.

  Specific examples of the substance that generates gas by being vaporized by heat 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, dichloroethylene, trichloroethane, trichloroethylene; etc., or azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, toluenesulfonylhydrazide Solids such as derivatives, aromatic succinyl hydrazide derivatives and the like.

  In the present invention, the content of the thermally expandable microcapsule is preferably 1 to 30 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the diene rubber (A). preferable.

<Silane coupling agent>
When the tire rubber composition of the present invention contains the above-described white filler (particularly silica), it is preferable to contain a silane coupling agent for the purpose of improving the reinforcing performance of the tire.
The content when the silane coupling agent is blended is preferably 0.1 to 20 parts by mass and more preferably 4 to 12 parts by mass with respect to 100 parts by mass of the white filler.

  Specific examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, Bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxy Silane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N- Methylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl Methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, Dimethoxymethylsilylpropylbenzothiazole tetrasulfide and the like, and these may be used alone, It may be used in combination with more species.

  Of these, bis- (3-triethoxysilylpropyl) tetrasulfide and / or bis- (3-triethoxysilylpropyl) disulfide is preferably used from the viewpoint of reinforcing effect. Specifically, Examples thereof include Si69 [bis- (3-triethoxysilylpropyl) tetrasulfide; manufactured by Evonik Degussa], Si75 [bis- (3-triethoxysilylpropyl) disulfide; manufactured by Evonik Degussa).

<Other ingredients>
In addition to the components described above, the rubber composition for tires of the present invention includes a filler such as calcium carbonate; a vulcanizing agent such as sulfur; and a vulcanization accelerator such as a sulfenamide, guanidine, thiazole, thiourea, and thiuram. Agents: Vulcanization accelerators such as zinc oxide and stearic acid; waxes; aroma oils; anti-aging agents; plasticizers; and other various additives commonly used in tire rubber compositions be able to.
As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used. For example, for 100 parts by mass of the diene rubber (A), 0.5 to 5 parts by mass of sulfur, 0.1 to 5 parts by mass of the vulcanization accelerator, and 0.1 to 10 parts by mass of the vulcanization accelerator aid. Parts, anti-aging agent 0.5-5 parts by mass, wax 1-10 parts by mass, aroma oil 5-50 parts by mass, respectively.

<Method for producing rubber composition for tire>
The method for producing the tire rubber composition of the present invention is not particularly limited. For example, the above-described components are kneaded using a known method or apparatus (for example, a Banbury mixer, a kneader, a roll, or the like). Is mentioned.
The tire rubber composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

〔studless tire〕
The studless tire of the present invention (hereinafter also simply referred to as “the tire of the present invention”) is a studless tire using the above-described tire rubber composition of the present invention for a tire tread.
FIG. 1 shows a schematic partial sectional view of a tire representing an example of an embodiment of the studless tire of the present invention, but the tire of the present invention is not limited to the embodiment shown in FIG.

In FIG. 1, the code | symbol 1 represents a bead part, the code | symbol 2 represents a sidewall part, and the code | symbol 3 represents the tread part comprised from the rubber composition for tires of this invention.
Further, a carcass layer 4 in which fiber cords are embedded is mounted between the pair of left and right bead portions 1, and the end of the carcass layer 4 extends from the inside of the tire to the outside around the bead core 5 and the bead filler 6. Wrapped and rolled up.
In the tire tread 3, a belt layer 7 is disposed over the circumference of the tire on the outside of the carcass layer 4.
Moreover, in the bead part 1, the rim cushion 8 is arrange | positioned in the part which touches a rim | limb.

  The tire of the present invention is vulcanized or cured at a temperature corresponding to, for example, the type of diene rubber, vulcanization or crosslinking agent, vulcanization or crosslinking accelerator used in the tire rubber composition of the present invention, and the blending ratio thereof It can manufacture by bridge | crosslinking and forming a tire tread part.

[Hardened product 1]
<Crosslinkable polymer C-1>
As the crosslinkable polymer C-1, hydrolyzable silyl group-terminated polyoxypropylene glycol (MS polymer S810, manufactured by Kaneka Corporation) was used.

<Foaming component D-1>
As the chemical foaming agent d1-1, azodicarbonamide (Vinole AC # 3, manufactured by Eiwa Chemical Industry Co., Ltd.) was used.
Urea (cell paste M3, manufactured by Eiwa Kasei Kogyo Co., Ltd.) was used as the foaming aid d2-1.
A foaming component D-1 was prepared by mixing the chemical foaming agent d1-1 and the foaming aid d2-1 so that the mass ratio (d1-1 / d2-1) was 1.0.

<Preparation of cured product 1>
The above-mentioned crosslinkable polymer C-1 and foaming component D-1 were mixed so that the mass ratio (C-1 / D-1) was 1.67 to prepare a mixture.
16 parts by mass of the prepared mixture and 1 part by mass of lactic acid (acid catalyst) were mixed and sufficiently stirred, and then cured at room temperature for 2 days to prepare cured product 1.

[Hardened product 2]
A cured product 2 was prepared in the same manner as the cured product 1 except that a foamed component D-2 shown below was used instead of the foamed component D-1 and a cured product was prepared by the method shown below.

<Foaming component D-2>
A foaming component D-2 was prepared by mixing the chemical foaming agent d1-1 and the foaming aid d2-1 described above so that the mass ratio (d1-1 / d2-1) was 1.67.

<Preparation of cured product 2>
The above-mentioned crosslinkable polymer C-1 and the prepared foaming component D-2 were mixed so that the mass ratio (C-1 / D-2) was 1.25 to prepare a mixture.
18 parts by mass of the prepared mixture and 1 part by mass of lactic acid (acid catalyst) were mixed and sufficiently stirred, and then cured at room temperature for 2 days to prepare cured product 2.

[Hardened product 3]
A cured product 3 was prepared in the same manner as the cured product 1 except that a cured product was prepared by the method described below.

<Preparation of cured product 3>
The above-mentioned crosslinkable polymer C-1 and the prepared foaming component D-1 were mixed so that the mass ratio (C-1 / D-1) was 0.83 to prepare a mixture.
After 22 parts by mass of the prepared mixture and 1 part by mass of lactic acid (acid catalyst) were mixed and sufficiently stirred, cured product 3 was prepared by curing at room temperature for 2 days.

[Hardened product 4]
A cured product 4 was prepared in the same manner as the cured product 1 except that a metal catalyst and an amine catalyst were used instead of the acid catalyst and a cured product was prepared by the method shown below.

<Preparation of cured product 4>
16 parts by mass of the prepared mixture, 0.3 part by mass of tin octylate (metal catalyst) and 0.1 part by mass of laurylamine (amine catalyst) were mixed and sufficiently stirred, and then cured at room temperature for 2 days. By doing so, the cured product 4 was prepared.

[Hardened product 5]
A cured product 5 was prepared in the same manner as the cured product 2 except that a metal catalyst and an amine catalyst were used instead of the acid catalyst, and a cured product was prepared by the method described below.

<Preparation of cured product 5>
18 parts by mass of the prepared mixture, 0.3 part by mass of tin octylate (metal catalyst) and 0.1 part by mass of laurylamine (amine catalyst) were mixed and sufficiently stirred, and then cured at room temperature for 2 days. By doing so, the cured product 5 was prepared.

[Hardened product 6]
A cured product 6 was prepared in the same manner as the cured product 1 except that a cured product was prepared by the method described below.
<Preparation of cured product 6>
The above-mentioned crosslinkable polymer C-1 and the prepared foaming component D-1 were mixed so that the mass ratio (C-1 / D-2) was 2.50 to prepare a mixture.
After 14 parts by mass of the prepared mixture and 1 part by mass of lactic acid (acid catalyst) were mixed and sufficiently stirred, cured product 6 was prepared by curing at room temperature for 2 days.

[Hardened product 7]
A cured product 7 was prepared in the same manner as the cured product 1 except that the foamed component D-3 shown below was used instead of the foamed component D-1 and a cured product was prepared by the method shown below.
<Foaming component D-3>
A foaming component D-3 was prepared by mixing the chemical foaming agent d1-1 and the foaming aid d2-1 described above so that the mass ratio (d1-1 / d2-1) was 2.00.
<Preparation of cured product 7>
The above-mentioned crosslinkable polymer C-1 and the prepared foaming component D-3 were mixed so that the mass ratio (C-1 / D-3) was 3.33 to prepare a mixture.
After 13 parts by weight of the prepared mixture and 1 part by weight of lactic acid (acid catalyst) were mixed and sufficiently stirred, cured product 7 was prepared by curing at room temperature for 2 days.

<Examples 1 to 10 and Comparative Examples 1 to 6>
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in Table 1 below.
Specifically, first, among the components shown in Table 1 below, components other than the cured products 1 to 7 and sulfur and the vulcanization accelerator were kneaded for 5 minutes with a 1.7 liter closed mixer, and 150 ° C. When it reached, it was discharged to obtain a master batch. In Comparative Examples 2 to 5 and Examples 1 and 2 prepared without blending the cured product, the chemical foaming agent d1-1 and the foaming aid d2-1 were previously prepared in a mass ratio shown in Table 1 below. Mixed foaming ingredients were blended.
Next, hardened | cured material 1-7 and sulfur and a vulcanization accelerator were knead | mixed by the open roll with the obtained masterbatch, and the rubber composition was obtained.
Next, the obtained rubber composition was vulcanized in a predetermined mold at 170 ° C. for 10 minutes to produce a vulcanized rubber composition.

<Performance on ice>
Each prepared vulcanized rubber composition was affixed to a flat columnar base rubber, and the coefficient of friction on ice was measured with an inside drum type on-ice friction tester. The measurement temperature was −1.5 ° C., the load was 5.5 g / cm ³ , and the drum rotation speed was 25 km / h.
The test results were expressed as an index according to the following formula, with the measured value of Comparative Example 1 being 100, and listed in the column “Performance on ice” in Table 1. The larger the index, the greater the frictional force on ice and the better the performance on ice.
Index = (Measured value / Coefficient of friction on ice of test piece of Comparative Example 1) × 100

<Hardness change rate (index of long-term stability)>
The hardness (A) of each vulcanized rubber composition prepared was measured at 20 ° C. with a JIS hardness meter.
Next, after the vulcanized rubber composition whose hardness (A) was measured was allowed to stand at 70 ° C. for 168 hours, the hardness (B) was measured at 20 ° C. using a similar JIS hardness meter.
Thereafter, the ratio (A / B) of the measured hardness (A) and hardness (B), that is, the rate of change in hardness was calculated.
The test results were expressed as an index using the following formula, with the measured value of Comparative Example 1 being 100, and listed in the column of “Hardness change rate” in Table 1. The smaller the index, the better the long-term stability.
Index = (calculated value / calculated value of test piece of Comparative Example 1) × 100

The following components were used as the components in Table 1.
・ NR: Natural rubber (STR20)
BR: Polybutadiene rubber (Nipol BR1220, glass transition temperature: −110 ° C., manufactured by Nippon Zeon)
Silica: 7000GR (CTAB adsorption specific surface area: 160 m ² / g, manufactured by Evonik Degussa)
Carbon black: Show black N339 (nitrogen adsorption specific surface area: 88 m ² / g, manufactured by Cabot Japan)
・ Silane coupling agent: Silane coupling agent (Si69, manufactured by Evonik Degussa)
Crosslinkable polymer C-1: Hydrolyzable silyl group-terminated polyoxypropylene glycol (MS polymer S810, manufactured by Kaneka Corporation)
-Cured products 1-7: manufactured as described above-Chemical foaming agent d1-1: Azodicarbonamide (Vinole AC # 3, manufactured by Eiwa Kasei Kogyo Co., Ltd.)
・ Foaming aid d2-1: Urea (Cell Paste M3, manufactured by Eiwa Kasei Kogyo Co., Ltd.)

-Thermal expansion microcapsule: Microsphere F100 (Matsumoto Yushi Seiyaku Co., Ltd.)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
・ Stearic acid: Bead stearic acid YR (manufactured by NOF Corporation)
Anti-aging agent: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine (Santflex 6PPD, manufactured by Flexis)
・ Wax: Paraffin wax (Ouchi Shinsei Chemical Co., Ltd.)
・ Oil: Extract No. 4 S (made by Showa Shell)
・ Sulfur: Oil-treated sulfur (made by Hoso Chemical)
・ Vulcanization accelerator 1: N-cyclohexyl-2-benzothiazolylsulfenamide (Sunseller CM-G, manufactured by Sanshin Chemical Co., Ltd.)
・ Vulcanization accelerator 2: Diphenylguanidine (PERKACIT DPG GRS, manufactured by FLEXSYS)

From the results shown in Table 1, it was found that the rubber composition of Comparative Example 2 prepared without blending the crosslinkable oligomer or polymer (C) had the same performance on ice and long-term stability as Comparative Example 1. It was.
Further, the rubber composition of Comparative Example 3 having a total content of the crosslinkable oligomer or polymer (C) and the foaming component (D) of more than 30 parts by mass with respect to 100 parts by mass of the diene rubber (A) is long-term. It was found that although stability was good, performance on ice was hardly improved.
The rubber compositions of Comparative Examples 4 and 5 in which the mass ratio (d1 / d2) of the chemical foaming agent (d1) and the foaming aid (d2) is outside the range of 0.3 to 2.0 are both It was found that the performance on ice and long-term stability were comparable to those of Comparative Example 1.
Further, the rubber composition of Comparative Example 6 having a mass ratio (C / D) of the crosslinkable oligomer or polymer (C) and the foaming component (D) of more than 3.0 is Comparative Example 1 in terms of performance on ice and long-term stability. It was found to be equivalent to

In contrast, the foaming component in which the mass ratio (d1 / d2) of the crosslinkable oligomer or polymer (C), the chemical foaming agent (d1) and the foaming aid (d2) is within the range of 0.3 to 2.0. It was found that all of the rubber compositions of Examples 1 to 10 in which (D) was blended at a predetermined mass ratio had better performance on ice and long-term stability than Comparative Example 1.
Further, from the comparison of Examples 1 to 7, the performance on ice and long-term stability are better by mixing the crosslinkable oligomer or polymer (C) and the foaming component (D) in advance and blending the cured product. It turns out that there is a tendency to become.
Moreover, it turned out that the performance on ice becomes more favorable by mix | blending a thermal expansion microcapsule from the comparison with Example 1 and Example 9, and the comparison with Example 3 and Example 10. FIG.

1 Bead part 2 Side wall part 3 Tire tread part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims (6)

Diene rubber (A),
Carbon black and / or white filler (B);
A crosslinkable oligomer or polymer (C) that is incompatible with the diene rubber (A);
A foaming component (D) in which a chemical foaming agent (d1) and a foaming aid (d2) are mixed at a mass ratio (d1 / d2) of 0.3 to 2.0, and
Content of the said carbon black and / or white filler (B) is 30-100 mass parts with respect to 100 mass parts of said diene rubber (A),
The total content of the crosslinkable oligomer or polymer (C) and the foaming component (D) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber (A),
The rubber composition for tires whose mass ratio (C / D) of the said crosslinkable oligomer or polymer (C) and the said foaming component (D) is 0.80-3.0.   The tire rubber composition according to claim 1, wherein the crosslinkable oligomer or polymer (C) and the foaming component (D) are contained as a mixture obtained by mixing them in advance.   The crosslinkable oligomer or polymer (C) and the foaming component (D) are obtained by curing the mixture using at least one catalyst selected from the group consisting of an acid catalyst, an alkali catalyst, a metal catalyst, and an amine catalyst. The tire rubber composition according to claim 2, which is contained as a cured product.   The tire rubber composition according to any one of claims 1 to 3, wherein the chemical foaming agent (d1) is azodicarbonamide and / or dinitrosopentastyrenetetramine.   Furthermore, the rubber composition for tires in any one of Claims 1-4 containing a thermally expansible microcapsule.   The studless tire which uses the rubber composition for tires in any one of Claims 1-5 for a tire tread.