JP2007291178A - Rubber composition for tread, and tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for tread, capable of producing a tire improved in grip performance, especially dry grip performance while maintaining the tire's rolling resistance, its tread's abrasion resistance and the composition's processability, and to provide such a tire with a tread formed using the composition. <P>SOLUTION: The rubber composition for tread comprises a rubber component including a diene rubber, a composite of a modified styrene-butadiene rubber and water-glass, and as necessary, silica, and a silane coupling agent, wherein the amount of the composite is 3-150 pts.wt. based on 100 pts.wt. of the rubber component. The tread of the tire is formed using this rubber composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tread rubber composition used for forming a tread portion of a tire, and a tire having a tread portion made of the tread rubber composition.

  Both the grip performance required for the tire and the rolling resistance characteristic depend on the hysteresis loss of the rubber forming the tread portion. In general, when the hysteresis loss of rubber is increased, the gripping force is increased and the braking performance of the tire is improved. On the other hand, the rolling resistance is increased, resulting in an increase in fuel consumption. Thus, the grip performance and the rolling resistance characteristic are in a contradictory relationship.

In order to improve the grip performance of the tire, in the rubber composition for tread, a large amount of oil, a large amount of carbon black, a large amount of silica, tungsten, zinc, zirconium, zirconium silicate, zircon, At least one inorganic compound powder selected from the group consisting of barium sulfate, zinc white and titanium oxide is blended (see Patent Document 1), and resin fine particles composed of an acrylic resin or a urethane resin are blended (Patent Document 2). And 3) are known.
JP 2000-319447 A JP 2002-80642 A JP 2002-97303 A

  However, when a large amount of oil is blended in the rubber composition for a tread, the wear resistance of the tread portion is lowered, the grip performance of the tire is lowered at a low temperature, and the tread portion may be broken due to embrittlement. Arise. In addition, when carbon black is blended in a large amount, a poor dispersion of carbon black and other fillers may be caused, and the grip performance of the tire, in particular, the grip performance on the wet road surface (wet grip performance) may be deteriorated.

Silica is less effective in improving grip performance on dry road surfaces (dry grip performance) compared to carbon black having the same specific surface area, and it can be added in a large amount to the tread rubber composition. As a result, the processability of the rubber composition for tread is reduced.
Further, when the inorganic compound powder is blended with the rubber composition for tread, the wet grip performance can be improved while maintaining the rolling resistance characteristic of the tire. Other properties required for tires such as wear resistance may be reduced, and when the resin fine particles are blended, the processability of the tread rubber composition is lowered.

  An object of the present invention is to produce a tire having improved tire grip performance, particularly dry grip performance, while maintaining tire rolling resistance characteristics, tread wear resistance and processability of the tread rubber composition. An object of the present invention is to provide a rubber composition for a tread that can be used, and a tire in which a tread portion is formed using the rubber composition.

In order to achieve the above object, the rubber composition for a tread of the present invention is characterized by containing a rubber component containing a diene rubber and a composite of a modified styrene butadiene rubber and water glass.
The rubber composition for a tread of the present invention has good processability, and by using this rubber composition for a tread, a tread portion having good wear resistance can be formed, and good rolling resistance characteristics can be maintained. However, a tire with improved grip performance, particularly dry grip performance, can be manufactured.

Moreover, the rubber composition for treads of this invention is characterized by containing the said composite in the ratio of 3-150 weight part with respect to 100 weight part of said rubber components.
In this case, the effect of improving the grip performance of the tire, particularly the dry grip performance, can be further enhanced.
Further, a tread rubber composition of the present invention, the complex, relative to the modified styrene-butadiene rubber 100 parts by weight, the water glass, the conversion value of SiO _2, in a proportion of 3 to 80 parts by weight It is suitable.

In this case, the effect of improving the grip performance of the tire, particularly the dry grip performance, can be further enhanced.
The rubber composition for a tread of the present invention further contains silica and a silane coupling agent, and contains the silica at a ratio of 150 parts by weight or less with respect to 100 parts by weight of the rubber. It is preferable that the coupling agent is contained at a ratio of 1 to 30 parts by weight with respect to 100 parts by weight of the silica.

In this case, the mechanical strength and grip performance of the tire can be further improved.
Moreover, it is preferable that the rubber composition for a tread of the present invention further contains carbon black and contains the carbon black in a ratio of 100 parts by weight or less with respect to 100 parts by weight of the rubber component.
In this case, the grip performance of the tire can be further improved without causing problems such as poor dispersion of carbon black and other fillers in the tread rubber composition.

In the tread rubber composition of the present invention, the modified styrene butadiene rubber of the composite is preferably a modified styrene butadiene rubber having a carboxyl group and / or an amino group in the molecule.
In this case, the effect of improving the grip performance of the tire, particularly the dry grip performance, can be further enhanced.

In order to achieve the above object, the tire of the present invention has a tread portion made of the rubber composition for a tread of the present invention.
Since the tread portion of the tire of the present invention is formed using the rubber composition for a tread of the present invention, according to the present invention, the rolling resistance characteristic is good and the durability is reduced due to less wear. It is possible to provide a tire that is good and excellent in grip characteristics, particularly dry grip characteristics.

  According to the tread rubber composition and the tire of the present invention, good rolling resistance characteristics and good low fuel consumption characteristics, good wear resistance and good durability associated therewith, excellent grip characteristics and Accordingly, a tire having excellent braking performance can be provided. In addition, the present invention can be suitably used, for example, in applications for vehicle tires such as passenger cars, large automobiles, racing cars, and motorcycles.

The rubber composition for a tread of the present invention contains a rubber component containing a diene rubber and a composite of a modified styrene butadiene rubber and water glass.
In the rubber composition for a tread of the present invention, a rubber component containing a diene rubber is an essential component.
Examples of diene rubbers including diene rubber include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene propylene diene rubber (EPDM), and chloroprene. Examples thereof include rubber (CR) and acrylonitrile butadiene rubber (NBR). These diene rubbers are used alone or in admixture of two or more. Among these, the diene rubber is preferably SBR from the viewpoint of achieving both the wet grip performance of the tire formed using the rubber composition for tread and the rolling resistance characteristics.

Further, SBR is not particularly limited with respect to the amount of bound styrene, production method (emulsion polymerization method or solution polymerization method), types of oil-extended and non-oil-extended, etc., and the rubber composition for tread includes various known types. SBR can be used.
Among them, for example, the amount of bound styrene of SBR is not limited to this, but from the viewpoint of the reinforcing effect by silica and composite, which will be described later, and the mechanical strength of SBR, the center value thereof is preferably 20 to 20%. It is 45 weight%, More preferably, it is 25-35 weight%. When the amount of bound styrene is less than 20% by weight, the grip performance may be deteriorated, and when it exceeds 40% by weight, the rubber becomes hard particularly at a low temperature, which may cause a decrease in grip performance.

Further, the bound vinyl amount of SBR is not limited to this, but it is preferably 30 to 60% by weight, more preferably 35 to 55% by weight at the central value. If the amount of bound vinyl is less than 30% by weight, grip properties may be reduced, and if it exceeds 60% by weight, fuel consumption may not be reduced.
Moreover, the classification according to the production method of SBR is not particularly limited, and may be either emulsion polymerization SBR (E-SBR) or solution polymerization SBR (S-SBR), or a mixture thereof. . In particular, preferably, E-SBR or a mixture of E-SBR and S-SBR, in which the content of E-SBR is 70% by weight or more, can be mentioned.

  The molecular weight of the diene rubber is not particularly limited. For example, from the viewpoint of mechanical strength of the diene rubber, the weight average molecular weight <Mw> is preferably 500,000 to 250 in terms of GPC method and polystyrene. And more preferably 600,000 to 2,000,000. If the weight average molecular weight <Mw> is less than 500,000, the wear resistance of the tire may be reduced. On the other hand, if it exceeds 2.5 million, the processability of the kneading process may be significantly reduced, and the production with the current polymer production technology becomes difficult due to the large molecular weight, which greatly increases the production cost There is.

Among the rubber components including the diene rubber, examples of the rubber other than the diene rubber include butyl rubber (IIR) and halogenated butyl rubber. These rubbers other than the diene rubber may be used alone or as 2 A mixture of seeds or more is used.
The content ratio of the diene rubber in the rubber component including the diene rubber is not particularly limited, but preferably from the viewpoint of imparting excellent grip performance to the tire formed using the rubber composition for treads. It is 10 weight% or more, More preferably, it is 15 weight% or more. In particular, the rubber component is preferably a diene rubber.

In the rubber composition for a tread of the present invention, a composite of a modified styrene butadiene rubber and water glass is an essential component. For example, the rolling resistance of a tire formed using the rubber composition for a tread is described above. Blended to improve grip performance while maintaining the properties.
Examples of the composite of the modified styrene butadiene rubber and water glass include a solidified product of an acid mixture of a modified styrene butadiene rubber latex and water glass.

  In the above composite, the modified styrene butadiene rubber (modified SBR) of the modified styrene butadiene rubber latex includes, for example, amino group, carboxyl group, carbamoyl group, N-hydroxycarbamoyl group, pyridyl group, epoxy group in the molecule. Styrene butadiene rubber having a substituent such as These substituents may be used alone or in combination of two or more.

  Among them, the modified SBR is preferably an SBR having an amino group in the molecule (amino-modified SBR), an SBR having a carboxyl group in the molecule (carboxylated SBR; hereinafter referred to as “XSBR”). And SBR having an amino group and a carboxyl group in the molecule (both amino group and carboxyl group-modified SBR latex; hereinafter referred to as “amino-modified XSBR”), and more preferably , XSBR or amino-modified XSBR.

In the modified SBR, the content of amino group or carboxyl group (weight ratio of amino group (—NH ₂ ) or carboxyl group (—COOH) to the entire rubber molecule of the modified SBR) is not particularly limited, but water glass described later From the viewpoint of the production efficiency of the composite and the effect of improving the grip performance of the tire, it is preferably 0.5% by weight or more, more preferably 2% by weight or more, and further preferably 2 to 20% by weight. is there.

  Specific examples of the modified SBR latex include, but are not limited to, for example, product name “Nipol LX407K3” manufactured by Nippon Zeon Co., Ltd. (amino-modified XSBR latex, total solid content 43 wt%, amino group content 0.5 to 5% by weight, carboxyl group content 0.5-5% by weight), product name “Nipol LX433” (XSBR latex, total solid content 50% by weight, carboxyl group content 0.2-3% by weight), etc. Can be mentioned.

Moreover, in the said composite_body | complex, water glass is normally shown by the following general formula.
Na ₂ O · nSiO ₂ · mH ₂ O
In the above general formula, n represents a molecular ratio of SiO ₂ / Na ₂ O and is not particularly limited, but is preferably 2.1 to 3.1, and more preferably 3.1. When n is 3.1, the content of the silicic acid component in the water glass (in terms of SiO ₂ ) increases, so that the effect of improving the grip performance of the tire due to the composite with the modified SBR is more effective. Further improve.

In addition, the water glass whose n in the said general formula is 3.1 is generally marketed as the water glass No.3. The water glass used in the rubber composition for a tread is not limited to this. For example, water glasses 1 to 3 defined in JIS K _1408-1966 , sodium metasilicate 1 to 2 types, and other various types. Grade products.
The composite of modified SBR and water glass is obtained, for example, by blending modified SBR latex and water glass, and further blending the resulting blended latex with an acid to coagulate the blended latex.

Examples of the acid include sulfuric acid and hydrochloric acid, and sulfuric acid is preferable.
In order to form a complex of modified SBR and water glass, the above modified SBR latex and the above water glass are blended, and after stirring, the above blended latex is blended with the above acid. The mixture is stirred for 2.5 hours, and then the agglomerated rubber is collected, and the collected rubber is washed with water until neutral, and dried.

The amount of water glass is not particularly limited, from the viewpoint of imparting excellent grip performance in a tire formed using the rubber composition for tread, the rubber per 100 parts by weight of the modified SBR latex, SiO ₂ The converted value is preferably 3 to 80 parts by weight, and more preferably 10 to 50 parts by weight.
In addition, when the rubber composition for treads using the composite which consists of amino modified XSBR and water glass as a composite of modified SBR and water glass is vulcanized by a conventional method to obtain a vulcanized rubber, for example. The loss factor (tan δ) of the obtained vulcanized rubber increases around (approximately in the range of 30 to 70 ° C.) around about 50 ° C. An increase in tan δ at 50 ° C. and in the vicinity thereof is effective in improving the grip performance, particularly the dry grip performance, of a tire having a tread portion made of a rubber composition for tread.

  Further, as a composite of modified SBR and water glass, for example, a rubber composition for tread using a composite made of XSBR and water glass is vulcanized by a conventional method to obtain a vulcanized rubber. The tan δ of the obtained vulcanized rubber rises around about 80 ° C. and in the vicinity thereof (generally in the range of 50 to 110 ° C.). Therefore, the grip performance of the tire, in particular, the dry grip performance can be improved.

  The compounding amount of the composite of the modified SBR and water glass is not particularly limited, and is sufficient to impart excellent grip performance and mechanical strength to the tire formed using the rubber composition for treads, And it sets in the range which does not reduce the workability of the said rubber composition for treads, workability | operativity, and the rolling resistance characteristic of the tire formed using the said rubber composition for treads. Specifically, it is preferably 3 to 150 parts by weight, more preferably 10 to 60 parts by weight, still more preferably 100 parts by weight of the rubber component containing the diene rubber of the rubber composition for treads. 15 to 35 parts by weight.

Silica is an optional component of the rubber composition for a tread, and is blended, for example, to impart excellent mechanical strength and grip performance to a tire formed using the rubber composition for a tread. .
The silica is not particularly limited, and various types of silica that are conventionally blended in rubber compositions for treads can be used. Specifically, amorphous silica (white carbon) such as hydrophilic or hydrophobic precipitated silica, hydrophilic or hydrophobic fumed silica, and calcium silicate, for example, can be mentioned. It is used individually or in mixture of 2 or more types.

Silica is not particularly limited in terms of its particle size, specific surface area, etc., and is appropriately set according to the balance between the reinforcing effect of silica and the processability of the rubber composition for treads. The specific surface area of the silica, for example, a nitrogen adsorption specific surface area (BET method), preferably a 80~350m ² / g, more preferably 100 to 250 m ² / g.
The compounding amount of silica is sufficient to impart excellent mechanical strength and grip performance to the tire formed using the tread rubber composition, and the processability and work of the tread rubber composition are sufficient. Specifically, the amount is set in a range in which the property is not lowered, and specifically, it is 5 to 150 parts by weight, preferably 10 to 120 parts per 100 parts by weight of the rubber component including the diene rubber of the rubber composition for tread. Parts by weight, more preferably 15 to 100 parts by weight.

The silane coupling agent is an optional component of the rubber composition for a tread, and improves, for example, the rolling resistance characteristics of a tire formed using the rubber composition for a tread and the wear resistance of a tread portion. To be blended.
The silane coupling agent is not particularly limited, and examples thereof include various silane coupling agents that are conventionally blended in a rubber composition for treads and are used in combination with the silica. Specifically, for example, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (2-triethoxysilyl) Ethyl) tetrasulfide, bis (3-triethoxysilylpropyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (2-methyldimethoxysilylethyl) tetrasulfide, bis (3-methyldimethoxysilylpropyl) Tetrasulfide, bis (4-methyldimethoxysilylbutyl) tetrasulfide, bis (2-methyldiethoxysilylethyl) tetrasulfide, bis (3-methyldiethoxysilylpropyl) tetrasulfide, bis (4-methyldiethoxy) Silylbutyl) tetrasulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis (2-triethoxysilylethyl) Trisulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (2-trimethoxysilylethyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (3-triethoxysilylpropyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (2-me Rudiethoxysilylethyl) disulfide, bis (3-methyldiethoxysilylpropyl) disulfide, bis (4-methyldiethoxysilylbutyl) disulfide, bis (2-methyldimethoxysilylethyl) disulfide, bis (3-methyldimethoxysilylpropyl) ) Disulfide, bis (4-methyldimethoxysilylbutyl) disulfide, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-aminopropyl Trimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane Γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and the like. These silane coupling agents are used alone or in admixture of two or more. The silane coupling agent is appropriately selected depending on the combination with silica, but among them, from the viewpoint of the ratio of the cost required for blending the silane coupling agent and the effect obtained for the cost, Bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide are mentioned, and bis (3-triethoxysilylpropyl) tetrasulfide is more preferred.

The blending amount of the silane coupling agent is set in consideration of cost-effectiveness within a range that is sufficient to improve the rolling resistance characteristics of the tire and the abrasion resistance of the tread portion. It is 1-30 weight part with respect to 100 weight part of said silica, Preferably, it is 2-20 weight part, More preferably, it is 2-15 weight part.
The tread rubber composition further optionally includes a vulcanizing agent, a vulcanization accelerator, a filler, a vulcanization acceleration aid, a vulcanization retarder, an anti-aging agent, a softening agent, a plasticizer, and the like. Additives are blended.

  The vulcanizing agent is an additive compounded to enable vulcanization molding of the rubber composition for tread. The vulcanizing agent is not particularly limited and includes various known vulcanizing agents. Specifically, for example, sulfur, organic sulfur-containing compounds (for example, N, N′-dithiobismorpholine, etc.), Organic peroxides (for example, benzoyl peroxide, dicumyl peroxide, etc.) may be mentioned, and these vulcanizing agents may be used alone or in combination of two or more. Of these, sulfur and organic sulfur-containing compounds are preferable, and sulfur is more preferable.

The blending amount of the vulcanizing agent is not particularly limited and is appropriately set according to a conventional method. Specifically, for example, it is preferably based on 100 parts by weight of the rubber component including the diene rubber of the rubber composition for tread. Is 0.5 to 3 parts by weight, more preferably 1 to 2 parts by weight.
A vulcanization accelerator is an additive blended to enable vulcanization molding of the rubber composition for treads. The vulcanization accelerator is not particularly limited and includes various known vulcanization accelerators. Specific examples include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and tetrabutylthiuram disulfide. (TBTD), tetrakis (2-ethylhexyl) thiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram tetrasulfide (TPTT) and other thiurams such as 2-mercaptobenzothiazole (MBT), dibenzothiazyl Disulfide (MBTS), zinc salt of 2-mercaptobenzothiazole (ZnMBT), cyclohexylamine salt of 2-mercaptobenzothiazole (CMBT), 2- (N, N′-diethylthiocarbamoylthio) benzoti Thiazoles such as azole and 2- (4-morpholinodithio) benzothiazole, for example, pentamethylenedithiocarbamic acid piperidine salt (PPDC), pipecolyldithiocarbamic acid pipecoline salt (PMPDC), dimethyldithiocarbamate zinc (ZnMDC), diethyldithiocarbamine Zinc oxide (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate (NaEDC), Sodium dibutyldithiocarbamate (NaBDC), dimethyldithiocarbamate body (CuMDC), ferric dimethyldithiocarbamate (FeMDC) , Dithiocarbamates such as tellurium diethyldithiocarbamate, such as N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N-oxy Sulfenamides such as diethylene-2-benzothiazolylsulfenamide (OBS) N, N′-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), for example, trimethylthiourea (TMU), N, N Thioureas such as' -diethylthiourea (DEU), for example, guanidines such as 1,3-diphenylguanidine (DPG), di-o-tolylguanidine (DOTG), 1-o-tolylbiguanide (OTBG), etc. Hexamethylenetetramine, n-butyl aldehyde Examples thereof include organic vulcanization accelerators such as doaniline and inorganic vulcanization accelerators such as slaked lime, magnesium oxide, titanium oxide, and resurge (PbO). These vulcanization accelerators are used alone or in admixture of two or more.

The blending amount of the vulcanization accelerator is not particularly limited and is appropriately set according to a conventional method. Specifically, for example, with respect to 100 parts by weight of the rubber component including the diene rubber of the rubber composition for tread, Preferably, it is 0.5-4 weight part, More preferably, it is 1-3 weight part.
Examples of the filler include carbon black, silica, talc, mica and the like.

Among the fillers, carbon black is blended, for example, to impart excellent mechanical strength to a tire formed using the rubber composition for treads.
The compounding amount of the carbon black is sufficient to impart excellent mechanical strength to the tire formed using the rubber composition for treads, and the processability and workability of the rubber composition for treads, etc. Specifically, the amount is 100 parts by weight or less, preferably 5 to 100 parts by weight with respect to 100 parts by weight of the rubber component including the diene rubber of the rubber composition for tread. More preferably, it is 25 to 60 parts by weight.

Examples of the vulcanization acceleration aid include stearic acid, oleic acid, and cottonseed fatty acid.
Examples of the vulcanization retarder include aromatic organic acids such as salicylic acid, phthalic anhydride, benzoic acid, N-nitrosodiphenylamine, N-nitroso-2,2,4-trimethyl-1,2-dihydroquinone, N- And nitroso compounds such as nitrosophenyl-β-naphthylamine.

  Examples of the antioxidant include imidazoles such as 2-mercaptobenzimidazole, such as phenyl-α-naphthylamine, N, N′-di-β-naphthyl-p-phenylenediamine, and N-phenyl-N′-isopropyl. Examples include amines such as -p-phenylenediamine, and phenols such as di-tert-butyl-p-cresol and styrenated phenol.

Examples of the softener include softeners such as vegetable oil, mineral oil, and synthetic oil, and specific examples include fatty acids (stearic acid, lauric acid, etc.), cottonseed oil, tall oil, and asphalt substances. And paraffin wax.
Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and the like.

Of the above additives, the compounding amount of additives other than carbon black is not particularly limited, but is usually preferably 50 parts by weight with respect to 100 parts by weight of the rubber component containing the diene rubber of the rubber composition for treads. Or less, more preferably 10 parts by weight or less.
The rubber composition for a tread includes a rubber component containing the diene rubber, a composite of the modified SBR and water glass, and optionally, silica, a silane coupling agent, and other additives. For example, it can be obtained by mixing by dry blending.

The dry blend is not particularly limited, and for example, a kneader such as a Banbury mixer, an open roll, a lab plast mill, or an extruder such as a single screw or twin screw may be used and kneaded according to a conventional method.
According to the rubber composition for a tread, the tire grip performance, particularly, the dry grip performance is improved while maintaining the rolling resistance characteristics of the tire, the wear resistance of the tread portion, and the processability of the rubber composition for the tread. Tires can be manufactured. Therefore, the rubber composition for a tread is suitable for providing a tire having good fuel economy characteristics and durability and excellent braking performance, such as a passenger car, a large automobile, a racing car, a motorcycle, and the like. It is suitable for use in vehicle tires.

The tire of this invention has the tread part which consists of a rubber composition for treads of the said invention.
The tire includes the above-described diene rubber, a rubber component, a composite composed of modified SBR and water glass, and optionally, a rubber composition for a tread including silica and a silane coupling agent. Vulcanization molding is carried out by a general method in the processing of tires using a kneaded product obtained by kneading and kneading a vulcanizing agent, a vulcanization accelerator, and optionally, other additives as described above. And manufactured.

That is, for example, the above-mentioned kneaded product is extruded to match the shape of the tire tread in an unvulcanized state, and on the tire molding machine, other tire parts (for example, a sidewall part, a shoulder part, a beat part, an inner part, etc. A non-vulcanized tire is formed by laminating with a member such as a liner. Next, the unvulcanized tire is heated and pressurized in a vulcanizer and vulcanized.
According to the tire, it is possible to improve the grip performance of the tire, particularly the dry grip performance, while maintaining the rolling resistance characteristics and the wear resistance of the tread portion. Therefore, the tire has good fuel economy characteristics and durability, and excellent braking performance, and is suitable as a tire for a vehicle such as a passenger car, a large vehicle, a racing car, and a motorcycle.

Next, an Example and a comparative example are given and this invention is demonstrated. The components used in the following examples and comparative examples are as follows.
SBR: Bonded styrene amount 23.5% by weight, product name “SBR1502”, manufactured by JSR Corporation.
Carbon black: nitrogen adsorption specific surface area (N ₂ SA) 111 m ² / g, product name “Show Black N220”, manufactured by Cabot Japan Co., Ltd.
Silica: Nitrogen adsorption specific surface area (N ₂ SA) 210 m ² / g, product name “Ultra Gil VN3”, manufactured by Degussa.
Silane coupling agent: bis (3-triethoxysilylpropyl) tetrasulfide, product name “Si69”, manufactured by Degussa.
Amino-modified XSBR latex (both amino group and carboxyl group modified SBR latex): total solid content 43 wt%, amino group content 0.5-5 wt%, carboxyl group content 0.5-5 wt%, product name “ "Nipol LX407K3", manufactured by Nippon Zeon Co., Ltd.
XSBR latex (carboxy-modified SBR latex): 50% by weight of total solids, carboxyl group content of 0.2 to 3% by weight, product name “Nipol LX433”, manufactured by Nippon Zeon Co., Ltd.
Water Glass: water glass No. _{3, Na 2 O · nSiO 2 ·} mH 2 O, n = 3.2, the content of the silicic acid component (SiO ₂ equivalent amount) of 28% equivalent, Fuji Chemical Co., Ltd..
Amino-modified XSBR-water glass composite (A): A mixture of 10 parts by weight of water glass with 100 parts by weight of the solid content of amino-modified XSBR latex, and agglomerated by adding sulfuric acid.
Amino-modified XSBR-water glass composite (B): A mixture of 25 parts by weight of water glass with 100 parts by weight of the solid content of amino-modified XSBR latex, and agglomerated with sulfuric acid.
XSBR-water glass composite (A): 10 parts by weight of water glass is added to 100 parts by weight of the solid content of XSBR latex, and sulfuric acid is added to agglomerate.
-XSBR-water glass composite (B): A mixture of 25 parts by weight of water glass with 100 parts by weight of the solid content of XSBR latex, and agglomerated by adding sulfuric acid.
Anti-aging agent: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, product name “NOCRACK 6C”, manufactured by Ouchi Shinsei Chemical Co., Ltd. • Stearic acid: Nippon Oil & Fats Co., Ltd. Product: Zinc oxide: Zinc Hua No. 2; Mitsui Mining & Smelting Co., Ltd .; Vulcanizing agent: Powdered sulfur; Tsurumi Chemical Industry Co., Ltd .; Thiazylsulfenamide (sulfenamide-based), product name “Noxeller NS”, Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator (DPG): N, N'-diphenylguanidine (guanidine series), product name "Noxeller D", Ouchi Shinsei Chemical Co., Ltd.
Example 1
100 parts by weight of SBR, 50 parts by weight of silica, 5 parts by weight of silane coupling agent, 20 parts by weight of amino-modified XSBR-water glass complex (A), 1 part by weight of anti-aging agent, and 2 parts by weight of stearic acid , 3 parts by weight of zinc oxide, 1.5 parts by weight of vulcanizing agent, 1 part by weight of vulcanization accelerator (BBS) and 0.5 part by weight of vulcanization accelerator (DPG) are mixed and kneaded. A rubber composition was obtained. Next, the obtained rubber composition was press vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized rubber (test piece).

Example 2
A rubber composition was obtained in the same manner as in Example 1 except that 20 parts by weight of the XSBR-water glass composite (A) was used instead of 20 parts by weight of the amino-modified XSBR-water glass composite (A). . Next, a vulcanized rubber was obtained in the same manner as in Example 1 using the obtained rubber composition.
Example 3
A rubber composition was obtained in the same manner as in Example 1 except that silica and a silane coupling agent were not blended. Next, the obtained rubber composition was press vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized rubber (test piece).

Example 4
A rubber composition was obtained in the same manner as in Example 1 except that the amount of silica was 25 parts by weight and the amount of the silane coupling agent was 5 parts by weight. Next, the obtained rubber composition was press vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized rubber (test piece).
Example 5
Further, a rubber composition was obtained in the same manner as in Example 1 except that 30 parts by weight of carbon black was blended. Next, a vulcanized rubber was obtained in the same manner as in Example 1 using the obtained rubber composition.

Comparative Example 1
A rubber composition was obtained in the same manner as in Example 1 except that the amino-modified XSBR-water glass composite was not blended. Next, a vulcanized rubber was obtained in the same manner as in Example 1 using the obtained rubber composition.
Comparative Example 2
A rubber composition was obtained in the same manner as in Example 1 except that the amino-modified XSBR-water glass composite was not blended and 50 parts by weight of carbon black was blended instead of 50 parts by weight of silica. Next, a vulcanized rubber was obtained in the same manner as in Example 1 using the obtained rubber composition.

Evaluation of physical properties The following physical properties (1) to (4) below were evaluated for the rubber compositions or vulcanized rubbers obtained in the respective Examples and Comparative Examples.
(1) Processability The Mooney viscosity (ML _{1 + 4} (130 ° C.)) at 130 ° C. of the rubber composition obtained in each example and each comparative example was determined according to JIS K 6300-1 _{: 2001} “Unvulcanized rubber. —Physical Properties—Measured according to the method (cutting method) specified in “Part 1: Determination of viscosity and coach time by Mooney viscometer”.

Next, based on the measured value ML _{1 + 4} (130 ° C.) of Comparative Example 1, from the following formula, in Examples 1 to 5 or Comparative Example 2 (hereinafter, physical property evaluation items (1) to (4), “each The measured value ML _{1 + 4} (130 ° C.) of “mixing”) was indexed.
(Mooney viscosity index) = (ML _{1 + 4} (130 ° C.) of Comparative Example 1) / (ML _{1 + 4} (130 ° C.) of each formulation) × 100
The larger the Mooney viscosity index calculated from the above formula, the lower the Mooney viscosity and the better the workability.

(2) Abrasion resistance The amount of lambone wear of the vulcanized rubber obtained in each example and each comparative example was determined according to the lamborn abrasion test method specified in JIS K _6264-1993 “Abrasion test method for vulcanized rubber”. The volume loss (cm ³ / min) was calculated under the conditions of 20 ° C., a load of 1.0 kgf (about 9.81 N), a slip rate of 20%, and a test time of 5 minutes.

Next, based on the volume loss amount of Comparative Example 1, the volume loss amount of each formulation was indexed from the following formula.
(Abrasion index) = (Volume loss amount of Comparative Example 1) / (Volume loss amount of each formulation) × 100
It shows that it is excellent in abrasion resistance, so that the abrasion index calculated from the said formula is large.
(3) Viscoelastic characteristics and rolling resistance characteristics In order to evaluate the rolling resistance characteristics of the vulcanized rubber obtained in each of the examples and comparative examples, the vulcanized rubber was evaluated using a viscoelastic spectrometer (model "VES", Temperature change of loss coefficient (tan δ) and storage elastic modulus E ′ under the conditions of initial strain 10% and dynamic strain 2% in a temperature range of −100 to + 150 ° C. Was measured.

The graph which shows the temperature change of tan-delta and the storage elastic modulus E 'is shown in FIGS. 1 and FIG. 2 are graphs comparing temperature changes of tan δ and storage elastic modulus E ′ for Example 1 and Comparative Example 1, respectively, and FIGS. 3 and 4 are for Example 2 and Comparative Example 1, respectively. Is a graph comparing temperature changes of tan δ and storage elastic modulus E ′, respectively.
Subsequently, tan δ of each formulation was indexed according to the following formula using tan δ of Comparative Example 1 as a reference.

(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100
The larger the rolling resistance index calculated from the above formula, the lower the rolling resistance and the better the rolling resistance characteristics.
(4) Grip characteristics In order to evaluate the grip characteristics of the vulcanized rubber obtained in each of the examples and comparative examples, the friction coefficient of the vulcanized rubber was measured using a flat belt tester (model “FR-5010”, ) Made by Ueshima Seisakusho. The measurement uses a cylindrical test piece with a width of 20 mm and a diameter of 10 mm. The measurement conditions are a road surface temperature of 20 ° C., a load of 4 kgf (about 39.2 N), a test piece speed of 20 km / hour, and the measurement sample slips on the road surface. The rate was changed from 0% to 70%, and the maximum value of the friction coefficient μ detected at that time was read.

Next, with the friction coefficient μ of Comparative Example 1 as a reference, the friction coefficient μ of each formulation was indexed by the following formula.
(Grip index) = (Grip index of Comparative Example 1) / (Grip index of each formulation) × 100
The larger the grip index calculated from the above equation, the better the grip characteristics.

  The results are shown in Table 1.

  As is clear from the comparison between Examples 1, 2, and 5 and Comparative Example 1, by containing the modified SBR-water glass composite, any one of workability, wear resistance, rolling resistance characteristics, and grip characteristics is obtained. Also improved. Moreover, in Example 4 with few compounding quantities of a silica, the rolling resistance characteristic was able to be improved significantly, maintaining workability, abrasion resistance, and a grip characteristic.

Further, as apparent from the comparison between Example 3 in which silica and a silane coupling agent were not blended with Comparative Example 2, the processability was reduced by containing the modified SBR-water glass composite. However, the wear resistance and grip control could be improved while maintaining the rolling resistance characteristics.
The present invention is not limited to the above description, and various design changes can be made within the scope of the matters described in the claims.

FIG. 1 is a graph comparing the temperature change of tan δ for Example 1 and Comparative Example 1. FIG. 2 is a graph comparing the temperature change of the storage elastic modulus E ′ for Example 1 and Comparative Example 1. FIG. 3 is a graph comparing the temperature change of tan δ for Example 2 and Comparative Example 1. FIG. 4 is a graph comparing the change in storage elastic modulus E ′ with respect to Example 2 and Comparative Example 1.

Claims (7)

  A rubber composition for a tread comprising a rubber component containing a diene rubber and a composite of a modified styrene butadiene rubber and water glass.   2. The rubber composition for a tread according to claim 1, wherein the composite is contained at a ratio of 3 to 150 parts by weight with respect to 100 parts by weight of the rubber. 2. The composite according to claim 1, wherein the composite contains 3 to 80 parts by weight of the water glass as a converted value of SiO ₂ with respect to 100 parts by weight of the modified styrene butadiene rubber. 2. The tread rubber composition according to 2. Furthermore, silica and a silane coupling agent are included,
The silica is contained at a ratio of 150 parts by weight or less with respect to 100 parts by weight of the rubber component,
The rubber composition for a tread according to any one of claims 1 to 3, wherein the silane coupling agent is contained in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the silica. In addition, including carbon black,
The rubber composition for a tread according to any one of claims 1 to 4, wherein the carbon black is contained at a ratio of 100 parts by weight or less with respect to 100 parts by weight of the rubber component.   The rubber composition for a tread according to any one of claims 1 to 5, wherein the modified styrene butadiene rubber of the composite is a modified styrene butadiene rubber having a carboxyl group and / or an amino group in a molecule. .   It has a tread part which consists of a rubber composition for treads in any one of Claims 1-6, The tire characterized by the above-mentioned.

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