JP2006225606A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in exothermicity together with retaining abrasion resistance and high elasticity. <P>SOLUTION: The pneumatic tire comprises the rubber composition comprising: a rubber component (A) composed of a rubber master batch obtained by mixing a rubber latex with a slurry solution which is a previously prepared dispersion of carbon black in water, and then coagulating; and a compound (B) having at least one group A in the molecule which is reactive to the rubber and at least two absorbing groups B to an inorganic filler. The rubber composition is used as a member of the tire. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire using a rubber composition in a tire tread portion.

  Conventionally, carbon black is frequently used as a reinforcing filler for rubber. This is because carbon black can provide high reinforcement and excellent wear resistance compared to other fillers.

  In addition, it is known to use a masterbatch as a method for producing rubber having excellent processability. This is because carbon black and water are mixed in a certain ratio in advance, and a slurry in which the filler is finely dispersed in water by mechanical force and rubber latex are mixed, and then coagulation of acid, inorganic salt, amine, etc. What is solidified by adding an agent is obtained by collecting and drying (see, for example, Patent Document 1).

On the other hand, by applying a rubber composition containing a specific compound with excellent compatibility with rubber components and affinity with inorganic fillers to tire members, it has high elasticity and low heat build-up, improving wear resistance. The technique to do is disclosed (for example, refer patent document 2).
JP 2004-99625 A JP 2004-231893 A

  By the way, in recent years, demand for low rolling resistance in the market and heat generation needs of large tires are increasing year by year.

  The above-described master batch is excellent in terms of greatly improving carbon dispersion and reducing heat generation. However, while improving the dispersion of carbon, it has been difficult to make a composition that satisfies the performance required by the market, such as ensuring the rigidity of the tire block, due to a significant decrease in the elastic modulus.

  Therefore, in view of the above problems, an object of the present invention is to provide a pneumatic tire that is excellent in heat generation and that has ensured wear resistance and high elasticity.

  The inventors of the present invention achieve the above object by using a masterbatch production method and incorporating a specific compound having excellent compatibility with the rubber component and affinity with the inorganic filler in the rubber composition. As a result, the present invention has been completed.

  A feature of the present invention is that a rubber latex (A) comprising a rubber master batch obtained by mixing a rubber latex and a slurry solution in which carbon black is previously dispersed in water and coagulating, and a reaction to rubber in the same molecule. The gist of the invention is a pneumatic tire using a rubber composition containing one or more groups A and a compound (B) having two or more adsorption groups B for an inorganic filler as a tire member.

  The tire member is preferably a tread.

  In the rubber composition according to the feature of the present invention, it is desirable to contain 0.3 to 20 parts by weight of the compound (B) per 100 parts by weight of the rubber component. When the amount is less than 0.3 parts by weight, the effect of improving the elastic modulus is small. When the amount is more than 20 parts by weight, the elastic modulus is remarkably increased and the heat generation is deteriorated, and there is a problem in terms of cost. The compound (B) is more preferably contained in 1 to 5 parts by weight.

  Further, in the step of mixing the rubber latex and the slurry solution in which carbon black is dispersed in water, the rubber composition according to the feature of the present invention is (i) the particle size distribution of carbon black in the water-dispersed slurry solution is: The volume average particle diameter (mv) is 25 μm or less, the 90 volume% particle diameter (D90) is 30 μm or less, and (ii) the 24M4DBP oil absorption amount of carbon black recovered by drying from the aqueous dispersion slurry solution is dispersed in water. It is desirable to maintain 93% or more of the previous 24M4DBP oil absorption. If the particle size is too large, the dispersion of the filler in the rubber may be deteriorated, and the reinforcing property and wear resistance may be deteriorated.

  The rubber master batch is desirably mixed by adding a surfactant to the rubber latex or slurry solution.

  Further, in the step of drying the rubber master batch after coagulation, it is desirable to perform drying while applying mechanical shearing force. By applying a mechanical shearing force, the dispersibility of the filler is further improved. Although this drying can be performed using a general kneader, it is desirable to use a continuous kneader from the viewpoint of industrial productivity. Furthermore, it is desirable to use a multi-shaft kneading extruder that rotates in the same direction or in different directions.

  In the rubber composition according to the feature of the present invention, the adsorptive group B is preferably a carboxyl group.

  In the rubber composition according to the feature of the present invention, the reactive group A is a group derived from an unsaturated carboxylic acid selected from maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid and sorbic acid. Is desirable.

  In the rubber composition according to the feature of the present invention, the compound (B) preferably further has an oxyalkylene group. By having an oxyalkylene group, the compatibility with rubber is improved and the affinity with an inorganic filler such as silica is improved.

  In the rubber composition according to the features of the present invention, the compound (B) is preferably a partial ester of a polybasic acid.

In the rubber composition according to the features of the present invention, the compound (B) is preferably a compound represented by the following chemical formula (II) or (III).

[In the formula (II), ^one of A ¹ , A ² and A ³ is a group represented by the formula — (R ¹ O) _n CO—CR ² ═CR ³ —R ⁴ (wherein R ¹ is an alkylene group having 2 to 4 carbon atoms, R ² , R ³ and R ⁴ are each independently a hydrogen atom or a methyl group, and n is a number from 1 to 30 indicating the average number of moles added of the oxyalkylene group. And others are hydrogen atoms]

[In the formula (III), R ⁸ represents a group represented by the formula —R ⁹ O—, a group represented by the formula — (R ¹⁰ O) S—, and a formula —CH ₂ CH (OH) CH ₂ O—. Or a group represented by the formula — (R ¹¹ O—COR ¹² —COO—) _t R ¹¹ O—. R ⁹ represents an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, R ¹⁰ represents an alkylene group having 2 to 4 carbon atoms, and s represents an average number of moles added of the oxyalkylene group. Number of 60, R ¹¹ is an alkylene group having 2 to 18 carbon atoms, alkenylene group, divalent aromatic hydrocarbon group or — (R ¹³ O) _u R ¹³ — (R ¹³ is an alkylene group having 2 to 4 carbon atoms) , U represents an average number of added moles of the oxyalkylene group, 1 to 30), R ¹² represents an alkylene group having 2 to 18 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, and t represents an average value of 1 Is a number of ~ 30]
In the rubber composition according to the feature of the present invention, it is desirable that the nitrogen adsorption specific surface area (N ₂ SA) of silica added later to the rubber master batch is 180 to 270 m ² / g. If it is smaller than 180 m ² / g, the chipping improvement due to the improvement of hysteresis loss is not sufficient, and if it is larger than 270 m ² / g, the factory workability is remarkably deteriorated when it is added later instead of the master batch. The amount of silica is not particularly limited, but is desirably 1 to 40 parts by weight per 100 parts by weight of the rubber component.

In the rubber composition according to the feature of the present invention, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black contained in the rubber master batch is 50 to 200 m ² / g, or the dibutyl phthalate oil absorption (DBP) is 60. It is preferable that the carbon black is contained in an amount of 20 to 80 parts by weight per 100 parts by weight of the rubber component. When the nitrogen adsorption specific surface area (N ₂ SA) is smaller than 50 m ² / g, the wear resistance is significantly lowered, and when it is larger than 200 m ² / g, exothermic heat and factory workability are deteriorated. Further, when the dibutyl phthalate oil absorption (DBP) is smaller than 60 ml / 100 g, sufficient wear resistance cannot be obtained, and when it is larger than 130 ml / 100 g, there is a concern that heat generation may be deteriorated. Further, if the amount of carbon black contained is less than 20 parts by weight, the exothermic property is excellent, but the wear resistance is remarkably impaired, and if it is more than 100 parts by weight, the exothermic property is deteriorated. Further, it is more desirable that the carbon black is contained in an amount of 30 to 60 parts by weight.

  In the rubber composition according to the feature of the present invention, the rubber master batch is preferably a natural rubber master batch. Natural rubber is a rubber excellent in mechanical properties, low heat build-up, and abrasion resistance, and has attracted attention as an environmentally friendly material.

  In addition, the rubber composition according to the features of the present invention is particularly preferably used for a tire tread portion of a heavy duty pneumatic tire, which requires both heat generation and wear resistance. Moreover, it can use especially suitably for an off-road tire.

  According to the present invention, it is possible to provide a pneumatic tire that is excellent in heat generation, and that has ensured wear resistance and high elasticity.

  Next, the present invention will be described in detail.

(Rubber composition)
The present invention is described in detail below.

  The pneumatic tire of the present invention comprises a rubber component (A) comprising a rubber masterbatch obtained by mixing a rubber latex and a slurry solution in which carbon black is previously dispersed in water and coagulating it, and rubber in the same molecule. A rubber composition containing a compound (B) having at least one reactive group A for a component and at least two adsorptive groups B for an inorganic filler is used for a tire member. Here, the tire member is preferably a tread. Since the compound (B) has one or more reactive groups A for the rubber component, it has excellent compatibility with the rubber component, and also has two or more adsorptive groups B for the inorganic filler. Excellent affinity. Therefore, by blending the rubber component with the compound (B) together with the inorganic filler, the dispersibility of the inorganic filler in the rubber component is improved, and the rubber composition can be made highly elastic. In addition, since the rubber composition has a high elastic modulus and improved rigidity, a tire using the rubber composition for a tread has improved wear resistance.

  The rubber component of the rubber composition used in the pneumatic tire of the present invention includes natural rubber (NR); polyisoprene rubber (IR), butyl rubber (IIR), polybutadiene rubber (BR), and styrene-butadiene copolymer rubber (SBR). ) And other synthetic diene rubbers. These rubber components may be used alone or in a blend. The rubber component preferably contains 20% by mass or more of natural rubber. When the content of the natural rubber in the rubber component is less than 20% by mass, the heat build-up of the rubber composition is deteriorated.

  The method for producing the master batch of the rubber component (A) will be described in detail later.

When an inorganic filler is added later to the master batch, silica is preferable as the inorganic filler to be used, and silica having a nitrogen adsorption specific surface area (N ₂ SA) of 180 to 270 m ² / g is particularly preferable. When the N ₂ SA of silica is less than 180 m ² / g, the effect of improving the chipping resistance due to the improvement of the hysteresis loss of the tire is small, and when it exceeds 270 m ² / g, the viscosity of the rubber composition increases and the workability during kneading is increased. Will get worse. The amount of silica is not particularly limited, but is desirably 1 to 40 parts by weight per 100 parts by weight of the rubber component. Moreover, although it does not specifically limit as silica used by this invention, Wet silica, dry silica, and colloidal silica are preferable.

  The rubber composition preferably further contains a silane coupling agent. By blending a silane coupling agent, the wear resistance of the tire is further improved and tan δ is further reduced. Here, as for the compounding quantity of a silane coupling agent, 1-20 mass parts is preferable with respect to 100 mass parts of inorganic fillers. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, and γ-glycidoxy. Propyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -Γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis (3- ( Triethoxysilyl) pro Le) tetrasulfide, bis (3- (triethoxysilyl) propyl) disulfide, .gamma.-trimethoxysilylpropyl dimethylthiocarbamoyl tetrasulfide, .gamma.-trimethoxysilylpropyl benzothiazyl tetrasulfide and the like.

  Next, the compound (B) having one or more reactive groups A for rubber and two or more adsorbing groups B for inorganic fillers in the same molecule will be described.

  The reactive group A for the rubber is preferably a group having a double bond, and a group that activates the double bond is preferably adjacent, particularly a non-aromatic conjugated double bond group or a double bond with a carbonyl group, It is preferable that one kind selected from a carboxyl group, an oxycarbonyl group and an amide group is an adjacent group. Here, the term “adjacent” means having one type selected from a carbonyl group, a carboxyl group, an oxycarbonyl group and an amide group at both ends or one side of the double bond.

  In the compound (B) of the present invention, the reactive group A is preferably a group derived from an unsaturated carboxylic acid selected from maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid or sorbic acid. Most preferred is a group derived from maleic acid, fumaric acid, itaconic acid or acrylic acid, particularly a group derived from maleic acid or acrylic acid. Regarding the adsorption group B, a carboxyl group is preferred.

  The compound (B) preferably further has an oxyalkylene group. By having an oxyalkylene group, the compatibility with rubber is further improved, and the affinity with an inorganic filler such as silica is further improved. The average added mole number of the oxyalkylene group is preferably in the range of 1 to 30 moles, more preferably in the range of 1 to 20 moles, particularly in the range of 2 to 15 moles, per number of reactive groups A to the rubber. It is preferable.

Specific examples of the compound (B) include mono ((meth) acryloyloxyalkyl) esters of polycarboxylic acids such as trimellitic acid, pyromellitic acid and citric acid (where ((meth) acryloyl is methacryloyl or acryloyl). (Poly) esters of unsaturated carboxylic acids such as maleic acid monomalate and oxycarboxylic acids; diols such as ethylene glycol, hexanediol, and cyclohexanedimethanol; and maleic acid, fumaric acid, itaconic acid, etc. An ester having a carboxyl group at both ends with a saturated dicarboxylic acid; N- (carboxyalkyl) maleamic acid such as N- (2-carboxyethyl) maleamic acid; a compound represented by the following chemical formula (II) or (III) Can be mentioned.

In the chemical formula (II), A ¹ , A ² and A ³ are groups in which one of them is represented by the formula — (R ¹ O) _n CO—CR ² ═CR ³ —R ⁴ (where R ¹ is an alkylene group having 2 to 4 carbon atoms, R ² , R ³ and R ⁴ are each independently a hydrogen atom or a methyl group, and n is a number from 1 to 30 indicating the average number of moles added of the oxyalkylene group). The other is a hydrogen atom. Here, R ¹ is an alkylene group having 2 to 4 carbon atoms, preferably an ethylene group or a propylene group. R ² , R ³ and R ⁴ are each independently a hydrogen atom or a methyl group, preferably R ² is a hydrogen atom or a methyl group, and R ³ and R ⁴ are hydrogen atoms. n is the number of 1-30 which shows the average addition mole number of an oxyalkylene group, Preferably it is 1-20, More preferably, it is a number of 2-15.

In the chemical formula (III), R ⁸ is represented by a group represented by the formula —R ⁹ O—, a group represented by the formula — (R ¹⁰ O) S—, or a formula —CH ₂ CH (OH) CH ₂ O—. Group or a group represented by the formula — (R ¹¹ O—COR ¹² —COO—) _t R ¹¹ O—. R ⁹ is an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, preferably an alkylene group having 2 to 18 carbon atoms or a phenylene group, more preferably 4 to 12 carbon atoms. An alkylene group. R ¹⁰ is an alkylene group having 2 to 4 carbon atoms, preferably an ethylene group or a propylene group. s is the number of 1-60 which shows the average addition mole number of an oxyalkylene group, Preferably it is 2-40, More preferably, it is a number of 4-30. R ¹¹ is an alkylene group having 2 to 18 carbon atoms, an alkenylene group, a divalent aromatic hydrocarbon group or — (R ¹³ O) _u R ¹³ — (R ¹³ is an alkylene group having 2 to 4 carbon atoms, u is is the number of 1 to 30 showing an average addition mole number of the oxyalkylene group, preferably 1 to 20, more preferably a number from 2 to 15), R ¹² represents an alkylene group having 2 to 18 carbon atoms, an alkenylene group Or it is a bivalent aromatic hydrocarbon group, Preferably it is a C2-C12 alkylene group or a phenylene group, More preferably, it is a C2-C8 alkylene group. t is an average value of 1 to 30, preferably 1 to 20, and more preferably 1 to 15.
Among these compounds, partial esters of polybasic acids are preferable, and compounds selected from compounds represented by the chemical formula (II) or (III) are more preferable.

  Specific examples of the compound represented by the chemical formula (II) include trimellitic acid mono (2- (meth) acryloyloxyethyl) ester, trimellitic acid mono [2- (2- (meth) acryloyloxyethoxy) ethyl]. Trimellitic acid mono (ω- (meth) acryloyloxyPOA (n)) esters such as esters and trimellitic acid mono (ω- (meth) acryloyloxypolyoxyethylene (10)) esters (where (meth) acryloyl is Methacryloyl or acryloyl, POA (n) is polyoxyethylene (hereinafter sometimes abbreviated as “POE”) or polyoxypropylene (hereinafter “POP”) in which 1 to 30 moles of oxyethylene or oxypropylene is added on average May be abbreviated as ")").

Specific examples of the compound represented by the chemical formula (III) include dimerates of alkylene diols such as glycerine dimaleate, 1,4-butanediol dimaleate, 1,6-hexanediol dimaleate, 1,6- Dialkylate of alkylene diol such as hexanediol difumarate, dimaleate of polyoxyalkylene glycol such as PEG200 dimaleate, PEG600 dimaleate (herein, PEG200 and PEG600 are polyethylene glycols having an average molecular weight of 200 or 600, respectively) at both ends Polybutylene maleate having a carboxyl group, poly (PEG200) maleate having a carboxyl group at both ends, and the like, both-end carboxylic acid type polyalkylene glycol / maleic polyester, carboxy at both ends Carboxylic acids at both ends such as polybutylene adipate maleate having a group, polyoxyalkylene glycol difumarate such as PEG600 difumarate, polybutylene fumarate having carboxyl groups at both ends, poly (PEG200) fumarate having carboxyl groups at both ends Type polyalkylene glycol / fumaric acid polyester.
The compound (B) preferably has a molecular weight of 250 or more, more preferably in the range of 250 to 5000, and particularly preferably in the range of 250 to 3000. Within this range, the flash point is high, which is desirable not only from the viewpoint of safety, but also from the viewpoint of the working environment because it produces less smoke. In addition, in this invention, the component of a compound (B) may be used independently and may be used in combination of 2 or more type.

  The compounding quantity of the said compound (B) is 0.5-20 mass parts with respect to 100 mass parts of rubber components, Preferably it is 0.5-10 mass parts, More preferably, it is 1-5 mass parts. When the compounding amount of the compound (B) is less than 0.5 parts by mass, the effect of improving the elastic modulus of the tire is small, and when it exceeds 20 parts by mass, the elastic modulus is remarkably improved and the cost is increased.

Moreover, the compounding quantity of carbon black is 20-80 mass parts with respect to 100 mass parts of rubber components, Preferably it is 30-60 mass parts. If the blending amount of carbon black is less than 20 parts by mass, the tire is excellent in reducing heat generation, but the wear resistance is remarkably reduced. If it exceeds 80 parts by mass, the exothermic property of the tire is remarkably increased, and the rubber composition is kneaded. Workability at the time is significantly reduced. The carbon black preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 30 to 160 m ² / g. If the N ₂ SA of the carbon black is less than 30 m ² / g, the tires are excellent in reducing heat generation, but the fracture characteristics such as wear resistance are remarkably reduced. If the N ₂ SA exceeds 160 m ² / g, the rubber composition Workability at the time of kneading is significantly reduced. Carbon black is classified into channel black, furnace black, acetylene black, thermal black and the like depending on the production method, and any of them can be used.

  The rubber composition includes, in addition to the rubber component, inorganic filler, silane coupling agent, compound (B), carbon black, compounding agents commonly used in the rubber industry, such as softeners, anti-aging agents, Vulcanizing agents, vulcanization accelerators, and the like can be appropriately blended depending on the purpose.

The addition method of the compound (B) in this invention is not specifically limited, It can add and mix to a rubber component using a normal kneader, for example, a Banbury mixer, a roll, an intensive mixer etc.
In addition, the rubber composition of the present invention includes various compounding agents usually used in the rubber industry, for example, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, as long as the object of the present invention is not impaired. An anti-scorch agent, a softening agent, zinc white, stearic acid and the like can be contained.

(Manufacturing method of master batch)
The rubber component of the rubber composition of the present invention comprises a rubber master batch. Although the manufacturing method of the natural rubber masterbatch which uses natural rubber latex is demonstrated below, this invention is applicable not only to a natural rubber masterbatch but to the masterbatch using synthetic rubbers, such as a diene type synthetic rubber.

  The production method of the natural rubber masterbatch according to the present invention is limited to the specific range of the particle size distribution of the filler in the water-dispersed slurry solution and the 24M4DBP oil absorption amount of the filler in the production of the slurry solution of the filler. The That is, in the step of mixing a natural rubber latex and a slurry solution in which carbon black is previously dispersed in water, (i) the particle size distribution of carbon black in the water-dispersed slurry solution has a volume average particle size (mv) of 25 μm. Below, 90 volume% particle size (D90) is 30 μm or less, and (ii) 24M4DBP oil absorption of carbon black dried and recovered from the water-dispersed slurry solution is 93% or more of 24M4DBP oil absorption before being dispersed in water It is necessary to hold. Here, the 24M4DBP oil absorption is a value measured according to ISO 6894.

  More preferably, the volume average particle diameter (mv) is 20 μm or less, and the 90 volume% particle diameter (D90) is 25 μm or less. If the particle size is too large, the filler dispersion in the rubber may be deteriorated, and the reinforcement and wear resistance may be deteriorated.

  On the other hand, if an excessive shearing force is applied to the slurry in order to reduce the particle size, the structure of the filler is destroyed and the reinforcing property is lowered. It is necessary that the 24M4DBP oil absorption amount of the filler dried and recovered from the aqueous dispersion slurry solution is 93% or more of the 24MDBP oil absorption amount of carbon black before being charged into the slurry. More preferably, it is 96% or more.

  A rotor / stator type high shear mixer, a high-pressure homogenizer, an ultrasonic homogenizer, a colloid mill, or the like is used for producing an aqueous dispersion slurry solution of carbon black.

For example, the slurry solution can be prepared by putting a predetermined amount of filler and water in a colloid mill and stirring at high speed for a certain time.

In the method for producing a natural rubber masterbatch of the present invention, as carbon black used, those usually used in the rubber industry can be used. For example, various grades of carbon black such as SAF, HAF, ISAF, FEF, and GPF can be used alone or in combination. Further, the carbon black contained in the rubber master batch has a nitrogen adsorption specific surface area (N ₂ SA) of 50 to 200 m ² / g, or a dibutyl phthalate oil absorption (DBP) of 60 to 130 ml / 100 g, and a rubber component of 100 weight. It is desirable to contain 20 to 100 parts by weight of the carbon black per part. Further, it is more desirable that the carbon black is contained in an amount of 30 to 60 parts by weight.

  The slurry concentration of the carbon black is preferably 0.5% by weight to 60% by weight with respect to the slurry, and a particularly preferable range is 1% by weight to 30% by weight.

  Next, as a mixing method of the slurry solution and the natural rubber latex, for example, the slurry solution is put in a homomixer and the latex is dropped while stirring, or the latex is stirred while the latex solution is stirred. There is a method of dropping the slurry solution. Also, a method of mixing a slurry flow having a constant flow rate and a latex flow under conditions of vigorous hydraulic stirring can be used.

  As a method for coagulating the masterbatch, it is carried out using a coagulant such as formic acid or sulfuric acid, or a salt such as sodium chloride as usual. In the present invention, coagulation may be performed by adding natural rubber latex and slurry without adding a coagulant.

  In addition to carbon black, various additives such as surfactants, vulcanizing agents, anti-aging agents, colorants, dispersants and other chemicals can be added to the masterbatch as desired.

  Drying is usually performed as the final step of master batch production. In the present invention, a normal dryer such as a vacuum dryer, an air dryer, a drum dryer, or a band dryer can be used. In order to further improve the dispersibility of the filler, a mechanical shear force is applied. It is preferable to perform drying. Thereby, rubber excellent in processability, reinforcement, and low fuel consumption can be obtained. Although this drying can be performed using a general kneader, it is preferable to use a continuous kneader from the viewpoint of industrial productivity. Furthermore, it is more preferable to use a twin-screw kneading extruder that rotates in the same direction or in different directions.

  In the step of drying while applying the shearing force, the moisture in the masterbatch before the drying step is preferably 10% or more. When this moisture is less than 10%, the improvement width of the filler dispersion in the drying process may be reduced.

  That is, the master batch in the present invention is a natural rubber master batch obtained by mixing and coagulating a slurry solution in which natural rubber latex and carbon black are previously dispersed in water.

(Pneumatic tire)
The rubber composition of the present invention described above is suitably used for tire tread rubber and tread base rubber. In addition, a pneumatic tire is manufactured by a normal method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into, for example, a tread member at an unvulcanized stage and pasted on a tire molding machine by a usual method. A green tire is formed by attaching. The green tire is heated and pressed in a vulcanizer to obtain a tire.

  The rubber composition of the present invention can be suitably used in various fields. However, as described above, the rubber composition having high elasticity, low heat generation and improved wear resistance is applied to a tire member. It is suitable as a heavy duty pneumatic tire. The tire is particularly suitable as an off-road tire for traveling on rough roads. In addition, as gas with which the pneumatic tire of this invention is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.

A rubber composition having the composition shown in Tables 1 to 3 was prepared, and a test tire (size: 3700R57) was prototyped using each rubber composition as a tread.

As shown in Table 1, silica may be added to the master batch or may be added by a dry mill after the master batch is prepared.

* 1 Trimetic acid monoacrylate (TMA)
* 2 Polybutanediol malate polyester * 3 PolyPEG 200 malate polyester Comparative Examples 4 to 5 and Examples 1 to 7 produced rubber compositions using a masterbatch. The masterbatch used here was as follows: It was manufactured by the manufacturing method.

A. Preparation of latex (1) Latex 1
Natural rubber field latex (rubber content 24.2%) was diluted with deionized water to give a rubber content of 20%.

(2) Latex 2
By adding 0.5% anionic surfactant (Kao Demol N) and 0.1% alkaline protease (Novozymes Alcalase 2.5L type DX) to Latex 1, and stirring at 40 ° C. for 8 hours, The amide bond in natural rubber was broken.

B. Stirring method of water dispersion slurry of carbon black (1) Stirring method 1
A colloid mill with a rotor diameter of 50 mm was charged with 1425 g of deionized water and 75 g of carbon black, and stirred for 10 minutes at a rotor-stator gap of 1 mm and a rotational speed of 1500 rpm.

(2) Stirring method 2
In the same manner as in the stirring method 1, stirring was performed for 10 minutes at a rotor-stator gap of 0.3 mm and a rotational speed of 5000 rpm.

(3) Stirring method 3
To the stirring method 1, 0.05% of an anionic surfactant (Kao Demol N) was further added, and the mixture was circulated three times using a pressure homogenizer at a pressure of 500 kPa.

(4) Stirring method 4
It was made to circulate 5 times on the conditions of the pressure of 1000 kPa similarly to the stirring method 3.

Table 4 shows the particle size distribution (mv, D90) of carbon black in the water-dispersed slurry obtained above, the 24M4DBP oil absorption (hereinafter referred to as 24M4DBP) of the carbon black collected by drying and its retention rate. In addition, 24M4DBP of carbon black before the slurry was charged is described in the note in Table 4.

(Note) 24M4DBP of carbon black before slurry introduction
N110; (24M4DBP: 98)
N220; (24M4DBP: 100)
N330; (24M4DBP: 88)
Moreover, various measurements in each slurry were performed as follows.

(I) Measurement of particle size distribution of carbon black in slurry solution (volume average particle diameter (mv), 90 volume% particle diameter (D90))
A laser diffraction particle size distribution meter (MICROTRAC FRA type) was used, and measurement was performed using an aqueous solvent (refractive index: 1.33). A particle refractive index of 1.57 was used for all measurements. Further, in order to prevent reaggregation of carbon black, measurement was performed immediately after dispersion.

(II) Carbon black 24M4DBP oil absorption was measured according to ISO 6894.

C. In the coagulation step homomixer, the latex and slurry prepared as above were added to 100 parts by weight of rubber so that each carbon black shown in Tables 2 and 3 was 50 parts by weight, while stirring, Formic acid was added until pH 4.5. The solidified master batch was collected, washed with water, and dehydrated until the water content was about 40%.

D. Drying process Using a band dryer method that uses a band dryer to dry at a temperature of 120 ° C., or using a Kobe Steel twin-screw kneading extruder (co-rotating screw diameter 30 mm, L / D = 35, 3 vent holes) This was carried out by any one of the twin-screw kneading extruder methods for drying at a temperature of 120 ° C. and a rotation speed of 100 rpm.

The amount of carbon black in the master batch obtained as described above was about 50 parts by weight with respect to 100 parts by weight of natural rubber.

E. Preparation of rubber composition 3 parts by weight of zinc oxide, 1.2 parts by weight of sulfur with respect to carbon black compounded rubber (100 parts by weight of natural rubber and 50 parts by weight of carbon black) obtained by the above masterbatch or dry kneading, 2 parts by weight of stearic acid, 1 part by weight of Nt-butyl-2-benzothiazolylsulfenamide (NS) and 1 part by weight of N-phenyl-N′-1,3-dimethylbutyl-p-phenylenediamine (6C) Parts were blended and kneaded with a plast mill to obtain a rubber composition.

  The test was conducted on the following items.

(1) Elastic modulus evaluation Using a spectrometer manufactured by Toyo Seiki Co., Ltd., the elastic modulus was measured at a strain of 1%, 50 Hz, and a temperature of 25 degrees. The larger the value, the richer the elastic modulus and the higher the rigidity.

(2) Evaluation of heat generation A drum test under constant speed and step load conditions was carried out, the temperature at a constant depth position inside the tire tread was measured, and the result of Comparative Example 1 was taken as 100 and displayed as an index. The larger the value, the greater the effect of reducing heat generation.

(3) Abrasion resistance evaluation The tread rubber in the tire after running for 2000 hours was calculated by (travel distance) / (groove depth before travel-groove depth after travel), and the result of Comparative Example 1 was taken as 100. displayed. It shows that the improvement effect of abrasion resistance is so large that a numerical value is large.

<Result>
From Table 3, it was found that the rubber compositions of Examples 1 to 7 were excellent in exothermic properties and ensured wear resistance and high elasticity compared to the rubber compositions of Comparative Examples 1 to 4. For this reason, by using a rubber component (A) consisting of a rubber masterbatch obtained by mixing a rubber latex and a slurry solution in which carbon black is dispersed in water and coagulating, it has excellent heat generation and wear resistance. And high elasticity can be secured.

Furthermore, it was found that the rubber compositions of Examples 1 to 7 were excellent in heat generation, and had high wear resistance and high elasticity compared to the rubber composition of Comparative Example 5. For this reason, in addition to the rubber component (A), by containing a compound (B) having one or more reactive groups A for rubber and two or more adsorbing groups B for inorganic filler in the same molecule, It was found that the heat generation was excellent, and abrasion resistance and high elasticity could be secured.

Claims (18)

A rubber component (A) comprising a rubber master batch obtained by mixing a rubber latex and a slurry solution in which carbon black is dispersed in water in advance, and solidifying the mixture;
An air using a rubber composition for a tire member, containing, in the same molecule, a compound (B) having one or more reactive groups A for the rubber and two or more adsorbing groups B for an inorganic filler. Enter tire.   The pneumatic tire according to claim 1, wherein the tire member is a tread.   The pneumatic tire according to claim 1 or 2, wherein 0.3 to 20 parts by weight of the compound (B) is contained per 100 parts by weight of the rubber component.   In the step of mixing the rubber latex and a slurry solution in which the carbon black is dispersed in water, (i) the particle size distribution of the carbon black in the water-dispersed slurry solution has a volume average particle diameter (mv) of 25 μm or less. , 90 volume% particle size (D90) is 30 μm or less, and (ii) 24M4DBP oil absorption of carbon black dried and recovered from the water-dispersed slurry solution holds 93% or more of 24M4DBP oil absorption before being dispersed in water The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is provided.   The pneumatic tire according to any one of claims 1 to 4, wherein the rubber master batch is mixed with a surfactant added to the rubber latex or the slurry solution.   The pneumatic tire according to any one of claims 1 to 5, wherein drying is performed while applying a mechanical shearing force in the step of drying the rubber master batch after coagulation.   The pneumatic tire according to claim 6, wherein drying is performed using a continuous kneader.   The pneumatic tire according to claim 7, wherein the continuous kneader is a double-screw kneading extruder.   The pneumatic tire according to claim 1, wherein the adsorption group B is a carboxyl group.   10. The reactive group A is a group derived from an unsaturated carboxylic acid selected from maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid and sorbic acid. The pneumatic tire according to item 1.   The pneumatic tire according to any one of claims 1 to 10, wherein the compound (B) further has an oxyalkylene group.   The pneumatic tire according to claim 1, wherein the compound (B) is a partial ester of a polybasic acid. The pneumatic tire according to any one of claims 1 to 12, wherein the compound (B) is a compound represented by any one of the following chemical formulas (II) and (III).

[In the formula (II), ^one of A ¹ , A ² and A ³ is a group represented by the formula — (R ¹ O) _n CO—CR ² ═CR ³ —R ⁴ (wherein R ¹ is an alkylene group having 2 to 4 carbon atoms, R ² , R ³ and R ⁴ are each independently a hydrogen atom or a methyl group, and n is a number from 1 to 30 indicating the average number of moles added of the oxyalkylene group. And others are hydrogen atoms]

[In the formula (III), R ⁸ represents a group represented by the formula —R ⁹ O—, a group represented by the formula — (R ¹⁰ O) S—, and a formula —CH ₂ CH (OH) CH ₂ O—. Or a group represented by the formula — (R ¹¹ O—COR ¹² —COO—) _t R ¹¹ O—. R ⁹ represents an alkylene group having 2 to 36 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, R ¹⁰ represents an alkylene group having 2 to 4 carbon atoms, and s represents an average number of moles added of the oxyalkylene group. Number of 60, R ¹¹ is an alkylene group having 2 to 18 carbon atoms, alkenylene group, divalent aromatic hydrocarbon group or — (R ¹³ O) _u R ¹³ — (R ¹³ is an alkylene group having 2 to 4 carbon atoms) , U represents an average number of added moles of the oxyalkylene group, 1 to 30), R ¹² represents an alkylene group having 2 to 18 carbon atoms, an alkenylene group or a divalent aromatic hydrocarbon group, and t represents an average value of 1 Is a number of ~ 30] The pneumatic tire according to any one of claims 1 to 13, wherein a nitrogen adsorption specific surface area (N ₂ SA) of silica added later to the rubber master batch is 180 to 270 m ² / g. The carbon black contained in the rubber master batch has a nitrogen adsorption specific surface area (N ₂ SA) of 50 to 200 m ² / g, or a dibutyl phthalate oil absorption (DBP) of 60 to 130 ml / 100 g.
The pneumatic tire according to any one of claims 1 to 14, wherein the carbon black is contained in an amount of 20 to 80 parts by weight per 100 parts by weight of the rubber component.   The pneumatic tire according to claim 1, wherein the rubber master batch is a natural rubber master batch.   The pneumatic tire according to any one of claims 1 to 16, wherein the pneumatic tire is a heavy duty pneumatic tire. The pneumatic tire according to claim 17, wherein the pneumatic tire is an off-road tire.