JP2011213913A - Rubber composition and tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire having rolling resistance and abrasion resistance balanced at high level.SOLUTION: The rubber composition contains carbon black for rubber compounding and a modified natural rubber in a specific ratio. The carbon black for rubber compounding is obtained by producing a high temperature combustion gas in a combustion gas producing zone, spraying and introducing a raw material into a reaction zone to form a reaction gas stream containing carbon black and quenching the reaction gas stream by a multistage quenching medium introducing means in a reaction stoppage zone to finalize the reaction. The modified natural rubber is formed by oxidizing natural rubber latex and adding a polar group-containing hydrazide compound into the terminal of the molecular chain of the natural rubber. The carbon black for rubber compound satisfies relation formulas of (1) 10<X<40 and (2) 90<Z<100, wherein X denotes the toluene coloring transmittance (%) of the carbon black after the first introduction of the quenching medium from a raw material introducing position and Z denotes the toluene coloring transmittance (%) of the carbon black after the final introduction of the quenching medium.

Description

  The present invention relates to a rubber composition and a tire using the rubber composition. More specifically, the present invention relates to a rubber composition containing a specific carbon black and containing a specific modified natural rubber, which gives a tire having an excellent balance between rolling resistance and wear resistance, and a tire using the same. Is.

Carbon black is generated in a furnace furnace under strictly controlled conditions, or sprayed with raw material hydrocarbons into a high-temperature combustion gas generated outside and introduced into the furnace. It is an industrially useful raw material produced by thermal decomposition or incomplete combustion. Carbon black has unique properties that can dramatically improve mechanical properties, especially tensile strength and wear resistance, with respect to the composition when blended with rubber. It is widely used as a filling reinforcement for various rubber products.
Carbon black for rubber compounding is based on its physicochemical characteristics, that is, the unit particle diameter, surface area per unit mass (specific surface area), particle connection condition (structure), surface properties, etc. Therefore, carbon black having different characteristics is selectively used depending on required rubber performance, environment in which it is used, and the like.

The rubber composition used for the tire contact surface has excellent resistance to wear (wear resistance) caused by rotating at high speed and coming into contact with the road, and at the same time, repeating the rubber composition generated by contact with the road surface. Decreasing the hysteresis loss characteristic due to deformation (low heat generation) is an important factor, but it is known that these two characteristics are antinomy.
When carbon black for tire tread blending is used to improve wear resistance, for example, when carbon black having a larger specific surface area or structure is used, as described above, wear resistance and low heat build-up are mutually contradictory. In order to solve this problem, carbon black having various characteristics has been proposed.

Until now, as a means of improving wear resistance in carbon black, the specific surface area {CTAB (cetyltrimethylammonium bromide) m ² / g} is increased to increase the contact area with the polymer, and DBP absorption Increasing the amount has been done to increase the interaction with the polymer. On the other hand, as means for reducing rolling resistance, reducing the specific surface area, reducing the contact area with the polymer, reducing DBP (dibutyl phthalate) absorption, and the like are performed.
As described above, it is difficult to simultaneously improve wear resistance and reduce rolling resistance as carbon black characteristics.
Therefore, as carbon black that simultaneously satisfies excellent wear resistance and excellent hysteresis characteristics (low heat generation), for example, (1) DBP absorption (DBP) is 40 to 250 ml / 100 g, (2) DBP absorption after compression operation Amount (24M4DBP) 35-220 ml / 100 g, (3) CTAB adsorption specific surface area (CTAB) 70-200 m ² / g, (4) Hydrogen release rate (%)> 0.260-0.000625 × (CTAB) (5) Carbon black for compounding tire tread rubber having a characteristic that the toluene coloring transmittance is 90% or more (for example, see Patent Document 1) is disclosed.

The improvement in tire wear resistance is considered to be governed by the particle size and structure of the carbon black compounded in the rubber composition constituting the tire. The smaller the carbon black particle size, the more wear resistance the tire has. Although improved, it is known that when the particle size of carbon black is extremely small, dispersion failure occurs in the rubber and heat generation increases. When a tire tread is produced with such a rubber composition, it is excellent in abrasion resistance but inferior in fuel efficiency. That is, the wear resistance and the low heat build-up are in a trade-off relationship with the carbon black particle size. Also, the structure tends to improve the wear resistance as the structure is increased. However, if the structure is increased too much, there are problems such as a decrease in workability and chipping resistance and an increase in heat generation.
Furthermore, although the wear resistance is increased to some extent by increasing the number of carbon black blended parts, the same concerns (such as a decrease in workability) arise as in the case of increasing the structure.

By the way, in recent years, there has been an increasing demand for a reduction in fuel consumption of automobiles in connection with the movement of the global regulation of carbon dioxide emissions accompanying an increase in interest in environmental problems. In order to meet such demands, reduction of rolling resistance is also demanded for tire performance. Conventionally, as a technique for reducing the rolling resistance of a tire, a technique for optimizing the tire structure has also been studied, but it is currently most important to use a rubber composition having lower heat generation as a rubber composition applied to the tire. This is done as a general method.
For example, in order to improve the affinity between the filler and the rubber component in the rubber composition and to improve the reinforcing effect by the filler, synthetic rubber or functional group having improved affinity with the filler by terminal modification Synthetic rubbers and the like have been developed in which the monomers are copolymerized to improve the affinity with the filler.
Patent Document 2 or 3 proposes a rubber composition using a modified conjugated diene polymer in which an amino group is introduced at a polymerization active terminal as a rubber component and carbon black as a filler in order to reduce rolling resistance. Yes.

On the other hand, with respect to natural rubber, a modification is obtained by adding a polar group-containing monomer to natural rubber latex, graft-polymerizing the polar group-containing monomer to natural rubber molecules in natural rubber latex, and further coagulating and drying. Using natural rubber as a rubber component improves the rubber composition's affinity with the filler and improves the rubber composition's reinforcement, improving the low loss, wear resistance and fracture characteristics of the rubber composition. The technique to make is disclosed (refer patent document 4).
Natural rubber has low heat build-up and excellent mechanical properties, and is used in many ways, including tread rubber for large tires, which can further improve the low loss and wear resistance of rubber compositions using natural rubber. It is requested.

JP 2005-272734 A JP-A-8-225604 JP-A-8-231658 International Publication No. 2004/106397 Pamphlet

  The present invention has been made under such circumstances, and a rubber including a modified natural rubber containing a specific carbon black and having a specific structure, which gives a tire having a high level of rolling resistance and wear resistance. The object is to provide a composition and a tire using the composition.

As a result of intensive research to achieve the above object, the present inventor has obtained carbon black having a specific property obtained by a specific process and a modified natural rubber having a specific structure as a rubber component. It has been found that the object can be achieved by the rubber composition contained in a proportion. The present invention has been completed based on such findings.
That is, the present invention
[1] Using a reaction apparatus in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, high-temperature combustion gas is generated in the combustion gas generation zone, and then a raw material is sprayed into the reaction zone Introducing a reaction gas stream containing carbon black, and then quenching the reaction gas stream by means of multistage rapid refrigerant introduction means in the reaction stop zone to terminate the reaction. A rubber composition comprising a modified natural rubber containing carbon black and having a polar group-containing compound added to natural rubber as a rubber component,
(1) The carbon black for rubber blending has the following relational expressions (1) and (2):
10 <X <40 (1)
90 <Z <100 (2)
(However, X represents the toluene coloring permeability (%) of carbon black after introduction of the first quenching medium from the raw material introduction position, and Z represents the toluene coloring permeability of carbon black after the last quenching medium introduction ( And (2) (B) the carbon black for rubber compounding in a proportion of 10 to 250 parts by mass with respect to 100 parts by mass of the rubber component containing (A) the modified natural rubber. A rubber composition characterized by comprising,
[2] The rubber composition according to [1], wherein an addition amount of the polar group-containing compound is 0.01 to 5.0% by mass with respect to the natural rubber.
[3] The polar group of the polar group-containing compound is an amino group, imino group, nitrile group, ammonium group, imide group, amide group, hydrazo group, azo group, diazo group, hydroxyl group, carboxyl group, carbonyl group, epoxy group. A rubber composition according to the above [1] or [2], which is at least one selected from the group consisting of: an oxycarbonyl group, a nitrogen-containing heterocyclic group, an oxygen-containing heterocyclic group, and a tin-containing group;
[4] The rubber composition according to [1] above, wherein the polar group-containing compound is a polar group-containing monomer, the monomer is grafted by emulsion polymerization, and the modified natural rubber into which the polar group-containing compound is introduced. object,
[5] The rubber composition according to [1], wherein the polar group-containing compound is a modified natural rubber in which the polar group-containing hydrazide compound is used.
[6] The rubber composition according to any one of the above [1] to [5] containing (A) a modified natural rubber in a proportion of 10% by mass or more in 100 parts by mass of the rubber component, and [7] the above [1] to [ 6], a tire using the rubber composition according to any one of
Is to provide.

The rubber composition of the present invention has the following effects by containing carbon black having a specific property obtained by a specific process and a specific modified natural rubber in a predetermined ratio.
(1) When carbon black is blended in a rubber composition, it is generally difficult to impart both excellent wear resistance and low heat build-up to the rubber composition, but the carbon black according to the present invention is used. As a result, it is possible to provide a rubber composition having a high balance between wear resistance and low heat build-up (low rolling resistance).
(2) The above carbon black has a hydrogen release rate higher than 0.30% by mass, and has a DBP absorption amount, a 24M4DBP absorption amount, and a CTAB adsorption specific surface area within specific ranges. It is suitable in terms of effects.
(3) When the rubber component of the rubber composition includes (A) a modified natural rubber modified with a monomer containing a polar group or a polar group-containing hydrazide compound, the above-described effect is more effectively exhibited. .
(4) The pneumatic tire obtained by using the rubber composition of the present invention is excellent in wear resistance and rolling resistance.

It is a partial longitudinal front explanatory drawing of an example of the carbon black manufacturing furnace for manufacturing carbon black for rubber compounding.

First, the rubber composition of the present invention will be described.
[(A) Modified natural rubber]
The modified natural rubber (A) used in the rubber composition of the present invention can be obtained by the following two methods.
(1) A method of adding a polar group-containing monomer to natural rubber latex, grafting the monomer by emulsion polymerization, and coagulating and drying the polymerization product.
(2) A method of simply introducing a polar group into the main chain of the natural rubber molecule of the natural rubber raw material by adding a polar group-containing hydrazide compound to a solid natural rubber raw material that can be obtained at low cost and directly reacting it. .
In the modified natural rubber obtained by the above methods (1) and (2), it is natural that the added amount of the polar group-containing compound is 0.01 to 5.0% by mass relative to the rubber content of the natural rubber. This is preferable because the excellent physical properties inherent to rubber are maintained.

First, the method (1) will be described in detail.
The modified natural rubber (A) used in the rubber composition of the present invention is obtained by adding a polar group-containing monomer to natural rubber latex, further adding a polymerization initiator and carrying out emulsion polymerization, and further coagulating the polymerization product. , Obtained by drying. As described above, since a small amount of polar group-containing monomer is graft-polymerized (emulsion polymerization) to natural rubber latex, the physical properties inherent to natural rubber are maintained. Moreover, since the monomer to be emulsion-polymerized has a polar group, it is possible to reduce odor generated during mastication. The reason is that it is presumed that the substance causing the odor is captured by the polar group and the odor is reduced. Furthermore, the graft polymerization of the polar group-containing monomer onto the natural rubber molecule not only improves the low heat buildup and wear resistance of the rubber composition but also slightly reduces the three-dimensional structure of the natural rubber molecule, resulting in static crystals. As a result, the freezing resistance during storage in a low temperature region, which has been a problem in the past, can be remarkably improved.

(latex)
The natural rubber latex used in the present invention is ordinary, and examples thereof include field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized latex treated with a surfactant and an enzyme, and combinations thereof. .

(Polar group-containing monomer)
The polar group-containing monomer used in the present invention is not particularly limited as long as it is a monomer having at least one polar group in the molecule. Specific examples of polar groups include amino groups, imino groups, nitrile groups, ammonium groups, imide groups, amide groups, hydrazo groups, azo groups, diazo groups, hydroxyl groups, carboxyl groups, carbonyl groups, epoxy groups, oxycarbonyl groups. Preferable examples include sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, nitrogen-containing heterocyclic groups, oxygen-containing heterocyclic groups, and tin-containing groups. These monomers containing polar groups can be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include polymerizable monomers having at least one amino group selected from primary, secondary, and tertiary amino groups in one molecule. Among these, tertiary amino group-containing monomers such as dialkylaminoalkyl (meth) acrylates are particularly preferable. These amino group-containing monomers can be used alone or in combination of two or more.

  Examples of primary amino group-containing monomers include acrylamide, methacrylamide, 4-vinylaniline, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, aminobutyl (meth) acrylate, and the like. Is mentioned.

  Secondary monomer-containing monomers include (1) anilinostyrene, β-phenyl-p-anilinostyrene, β-cyano-p-anilinostyrene, β-cyano-β-methyl-p-ani Linostyrene, β-chloro-p-anilinostyrene, β-carboxy-p-anilinostyrene, β-methoxycarbonyl-p-anilinostyrene, β- (2-hydroxyethoxy) carbonyl-p-anilinostyrene, anilinostyrenes such as β-formyl-p-anilinostyrene, β-formyl-β-methyl-p-anilinostyrene, α-carboxy-β-carboxy-β-phenyl-p-anilinostyrene, and the like; (2) Anilinophenyl butadiene, 1-anilinophenyl-1,3-butadiene, 1-anilinophenyl-3-methyl-1,3-butadiene, 1-anili Nophenyl-3-chloro-1,3-butadiene, 3-anilinophenyl-2-methyl-1,3-butadiene, 1-anilinophenyl-2-chloro-1,3-butadiene, 2-anilinophenyl- Anilinophenylbutadienes such as 1,3-butadiene, 2-anilinophenyl-3-methyl-1,3-butadiene, 2-anilinophenyl-3-chloro-1,3-butadiene, (3) N— Examples include N-monosubstituted (meth) acrylamides such as methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylolacrylamide, N- (4-anilinophenyl) methacrylamide and the like.

  Examples of the tertiary amino group-containing monomer include N, N-disubstituted aminoalkyl acrylates, N, N-disubstituted aminoalkylacrylamides, and vinyl compounds having a pyridyl group.

  Examples of the N, N-disubstituted aminoalkyl acrylate include N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N , N-dimethylaminobutyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-diethylaminobutyl (meth) acrylate, N-methyl-N- Ethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dibutylaminopropyl (meth) acrylate, N, N-dibutyl Aminobutyl (meth) acrylate DOO, N, N-dihexylaminoethyl (meth) acrylate, N, N-dioctyl aminoethyl (meth) acrylate, esters of acrylic acid or methacrylic acid such as acryloyl morpholine and the like. In particular, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-diocleaminoethyl (meth) acrylate N-methyl-N-ethylaminoethyl (meth) acrylate and the like are preferable.

  Examples of the N, N-disubstituted aminoalkylacrylamide include N, N-dimethylaminomethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N , N-dimethylaminobutyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-diethylaminobutyl (meth) acrylamide, N-methyl-N- Ethylaminoethyl (meth) acrylamide, N, N-dipropylaminoethyl (meth) acrylamide, N, N-dibutylaminoethyl (meth) acrylamide, N, N-dibutylaminopropyl (meth) acrylamide, N, N-dibutylamino Acrylamide compounds or methacrylamide compounds such as butyl (meth) acrylamide, N, N-dihexylaminoethyl (meth) acrylamide, N, N-dihexylaminopropyl (meth) acrylamide, N, N-dioctylaminopropyl (meth) acrylamide, etc. Is mentioned. In particular, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-dioctylaminopropyl (meth) acrylamide and the like are preferable.

  Moreover, a nitrogen-containing heterocyclic group may be sufficient instead of an amino group. Examples of the nitrogen-containing heterocycle include pyrrole, histidine, imidazole, triazolidine, triazole, triazine, pyridine, pyrimidine, pyrazine, indole, quinoline, purine, phenazine, pteridine, melamine and the like. The nitrogen-containing heterocycle may contain other heteroatoms in the ring.

  Examples of the vinyl compound having a pyridyl group include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, 5-ethyl 2-vinylpyridine and the like. In particular, 2-vinylpyridine, 4-vinylpyridine and the like are preferable.

  Examples of the nitrile group-containing monomer include (meth) acrylonitrile, vinylidene cyanide, and the like. These may be used alone or in combination of two or more.

  Examples of the hydroxyl group-containing monomer include polymerizable monomers having at least one primary, secondary, and tertiary hydroxyl group in one molecule. Examples of such monomers include hydroxyl group-containing unsaturated carboxylic acid monomers, hydroxyl group-containing vinyl ether monomers, and hydroxyl group-containing vinyl ketone monomers. Specific examples of such hydroxyl group-containing monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. Hydroxyalkyl (meth) acrylates such as 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; polyalkylene glycols such as polyethylene glycol and polypropylene glycol (the number of alkylene glycol units is, for example, 2- 23) mono- (meth) acrylates; N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N, N-bis (2-hydroxyethyl) (meth) acryl Hydroxyl group-containing unsaturated amides such as amides; o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, o-hydroxy-α-methylstyrene, m-hydroxy-α-methylstyrene, p-hydroxy-α- Examples include hydroxyl group-containing vinyl aromatic compounds such as methylstyrene and p-vinylbenzyl alcohol; (meth) acrylates. Among these, hydroxyl group-containing unsaturated carboxylic acid monomers, hydroxyalkyl (meth) acrylates, and hydroxyl group-containing vinyl aromatic compounds are preferable, and hydroxyl group-containing unsaturated carboxylic acid monomers are particularly preferable. Examples of the hydroxyl group-containing unsaturated carboxylic acid monomer include derivatives such as esters, amides, anhydrides and the like such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid, and particularly acrylic acid and methacrylic acid. The ester compound is preferred.

  Carboxyl group-containing monomers include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, tetraconic acid, cinnamic acid and other unsaturated carboxylic acids; or phthalic acid, succinic acid, adipic acid and other non-polymerizable Examples thereof include free carboxyl group-containing esters such as monoesters of polyvalent carboxylic acids and hydroxyl-containing unsaturated compounds such as (meth) allyl alcohol and 2-hydroxyethyl (meth) acrylate, and salts thereof. Of these, unsaturated carboxylic acids are particularly preferred. Such monomers may be used alone or in combination of two or more.

  Examples of the epoxy group-containing monomer include (meth) allyl glycidyl ether, glycidyl (meth) acrylate, 3,4-oxycyclohexyl (meth) acrylate, and the like. These monomers may be used alone or in combination of two or more.

(Polymerization initiator)
The initiator for graft polymerization is not particularly limited, and various initiators such as an initiator for emulsion polymerization can be used, and the addition method is not particularly limited. Examples of commonly used initiators include benzoyl peroxide, hydrogen peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, 2,2-azobisisobutyronitrile, 2, 2-azobis (2-diaminopropane) hydrochloride, 2,2-azobis (2-diaminopropane) dihydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile), potassium persulfate, sodium persulfate, Examples include ammonium sulfate. In order to reduce the polymerization temperature, it is preferable to use a redox polymerization initiator. Examples of the reducing agent used in combination with the peroxide used in the redox polymerization initiator include tetraethylenepentamine, mercaptans, acidic sodium sulfite, reducing metal ions, ascorbic acid and the like. In particular, a combination of tert-butyl hydroperoxide and tetraethylenepentamine is preferable as a redox polymerization initiator.

(polymerization)
The graft polymerization performed in the present invention is a general emulsion polymerization in which a polar group-containing monomer is added to natural rubber latex and polymerized while stirring at a predetermined temperature. Water and an emulsifier added to the polar group-containing monomer in advance and fully emulsified may be added to the natural rubber latex, or the polar group-containing monomer may be added directly to the natural rubber latex, if necessary An emulsifier may be added before or after the addition of the monomer. The emulsifier is not particularly limited, and examples thereof include nonionic surfactants such as polyoxyethylene lauryl ether.

  In consideration of maintaining the original physical properties of natural rubber, it is important to introduce a small amount of polar groups evenly into the natural rubber molecules, so the amount of polymerization initiator added is 100 moles of polar group-containing monomer. 1-100 mol% is preferable with respect to 10-100 mol%. A modified natural rubber latex is obtained by charging the above-described components into a reaction vessel and reacting at 30-80 ° C. for 10 minutes-7 hours to carry out graft polymerization. The modified natural rubber latex thus obtained is used in a solid state by further coagulation and drying. When used as a solid rubber, the rubber latex is first coagulated, washed, and then dried using a dryer such as a vacuum dryer, an air dryer, or a drum dryer.

  In the modified natural rubber used in the rubber composition of the present invention, the graft amount of the polar group-containing monomer is preferably 0.01 to 5.0% by mass with respect to the rubber content of the natural rubber latex. By setting the graft amount of the polar group-containing monomer within the above range, the natural physical properties (stress-strain curve in viscoelasticity, tensile test, etc.) of natural rubber can be maintained, and the rubber composition can be resistant. Abrasion and low heat generation can be improved.

Next, the method (2) will be described in detail.
The modified natural rubber used in the rubber composition of the present invention is obtained by adding a polar group-containing hydrazide compound to at least one natural rubber raw material selected from the group consisting of natural rubber, natural rubber latex coagulum and natural rubber cup lamp, The polar group-containing hydrazide compound can be obtained by adding to a natural rubber molecule in the natural rubber raw material.
Since the polar group of the polar group-containing hydrazide compound is excellent in affinity to various fillers such as carbon black and silica, the modified natural rubber has an affinity for various fillers compared to unmodified natural rubber. high. Therefore, the rubber composition of the present invention using the modified natural rubber as a rubber component has a high dispersibility of the filler with respect to the rubber component, and the reinforcing effect of the filler is sufficiently exhibited, resulting in fracture characteristics and wear resistance. In addition to being excellent, the low heat build-up (low loss) is also greatly improved. Further, by using the rubber composition for a tire, particularly a tread of the tire, it is possible to remarkably improve fracture resistance and wear resistance while greatly reducing rolling resistance.

  As raw materials of the modified natural rubber of the present invention, various solid natural rubbers after drying, various natural rubber latex coagulates (including unsmoked sheets) or natural rubber cup lamps can be used. These natural rubber raw materials are: You may use individually by 1 type and may be used in combination of 2 or more type. Since the production of the modified natural rubber of the present invention does not require the use of a natural rubber latex having a high purity, the modified natural rubber can be produced at a relatively low cost. Among the natural rubber raw materials, cup lamps and the like can be obtained at a low cost, so that there is a great merit in terms of cost. Note that when cup lamps or the like are used as raw materials, the modification efficiency of natural rubber may be slightly reduced, but the merit is superior in terms of the overall cost and modification efficiency.

  The polar group-containing hydrazide compound has high reactivity. Therefore, simply by adding the polar group-containing hydrazide compound to the natural rubber raw material, the hydrazide compound reacts with the aldehyde group in the natural rubber of the natural rubber raw material, and as a result, the polar group is contained in the natural rubber main chain. Can be simply introduced.

  The polar group-containing hydrazide compound is not particularly limited as long as it is a hydrazide compound having at least one polar group in the molecule. Specifically, for example, amino group, imino group, nitrile group, ammonium group, imide group, amide group, hydrazo group, azo group, diazo group, hydroxyl group, carboxyl group, carboxyl group, epoxy group, oxycarbonyl Preferred examples include a group, a nitrogen-containing heterocyclic group, an oxygen-containing heterocyclic group, and a tin-containing group. These polar group-containing hydrazide compounds can be used alone or in combination of two or more.

  Examples of the amino group-containing hydrazide compound include hydrazide compounds having at least one amino group selected from primary, secondary, and tertiary amino groups in one molecule. These amino group-containing hydrazide compounds can be used alone or in combination of two or more.

  Examples of the primary amino group-containing hydrazide compound include 2-aminoacetohydrazide, 3-aminopropanoic acid hydrazide, 4-aminobutanoic acid hydrazide, 2-aminobenzohydrazide, 4-aminobenzohydrazide and the like.

  Examples of secondary amino group-containing hydrazide compounds include 2- (methylamino) acetohydrazide, 2- (ethylamino) acetohydrazide, 3- (methylamino) propanoic acid hydrazide, and 3- (ethylamino) propanoic acid hydrazide. 3- (propylamino) propanoic hydrazide, 3- (isopropylamino) propanoic hydrazide, 4- (methylamino) butanoic hydrazide, 4- (ethylamino) butanoic hydrazide, 4- (propylamino) butanoic hydrazide 4- (isopropylamino) butanoic acid hydrazide, 2- (methylamino) benzohydrazide, 2- (ethylamino) benzohydrazide, 2- (propylamino) benzohydrazide, 2- (isopropylamino) benzohydrazide, 4- ( Methylamino) benzohydrazide 4- (ethylamino) benzohydrazide, 4- (propylamino) benzohydrazide, 4- (isopropylamino) benzohydrazide and the like.

  Examples of tertiary amino group-containing hydrazide compounds include N, N-disubstituted aminoalkyl hydrazide compounds and N, N-disubstituted benzohydrazide compounds. Examples of these compounds include 2- (dimethylamino) acetohydrazide, 2- (diethylamino) acetohydrazide, 3- (dimethylamino) propanoic acid hydrazide, 3- (diethylamino) propanoic acid hydrazide, and 3- (dipropylamino). ) Propanoic hydrazide, 3- (diisopropylamino) propanoic hydrazide, 4- (dimethylamino) butanoic hydrazide, 4- (diethylamino) butanoic hydrazide, 4- (dipropylamino) butanoic hydrazide, 4- (diisopropylamino) ) Butanoic acid hydrazide, 2- (dimethylamino) benzohydrazide, 2- (diethylamino) benzohydrazide, 2- (dipropylamino) benzohydrazide, 2- (diisopropylamino) benzohydrazide, 4- (dimethylamino) benzo Examples include hydrazide, 4- (diethylamino) benzohydrazide, 4- (dipropylamino) benzohydrazide, 4- (diisopropylamino) benzohydrazide and the like.

  Further, it may be a nitrogen-containing heterocyclic group instead of an amino group. Examples of the nitrogen-containing heterocyclic group include pyrrole, histidine, imidazole, triazolidine, triazole, triazine, pyridine, pyrimidine, pyrazine, indole, quinoline. , Purine, phenazine, pteridine, melamine and the like. The heteronitrogen heterocycle may contain other heteroatoms in the ring. Here, examples of the hydrazide compound having a pyridyl group as a nitrogen-containing heterocyclic group include isonicotinohydrazide and picolinohydrazide. These nitrogen-containing heterocyclic group-containing hydrazide compounds may be used alone or in combination of two or more.

  Examples of the hydrazide compound having a nitrile group include 2-nitroacetohydrazide, 3-nitropropanoic acid hydrazide, 4-nitrobutanoic acid hydrazide, 2-nitrobenzohydrazide, 4-nitrobenzohydrazide and the like. These nitrile group-containing hydrazide compounds may be used alone or in a combination of two or more.

  Examples of the hydroxyl group-containing hydrazide compound include hydrazide compounds containing at least one primary, secondary, or tertiary hydroxyl group in one molecule. Examples of such hydroxyl group-containing hydrazide compounds include 2-hydroxyacetohydrazide, 3-hydroxypropanoic hydrazide, 4-hydroxybutanoic hydrazide, 2-hydroxybenzohydrazide, and 4-hydroxybenzohydrazide. These hydroxyl group-containing hydrazide compounds may be used alone or in a combination of two or more.

  Examples of the hydrazide compound containing a carboxyl group include 3-carboxypropanoic acid hydrazide and 4-carboxybutanoic acid hydrazide. These carboxyl group-containing hydrazide compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the hydrazide compound having an epoxy group include 2- (oxiran-2-yl) acetohydrazide, 3- (oxiran-2-yl) propanoic acid hydrazide, and 3- (tetrahydro-2H-pyran-4-yl) propanoic acid. And hydrazide. These epoxy group-containing hydrazide compounds may be used alone or in a combination of two or more.

  Examples of the hydrazide compound having a tin-containing group include 3- (tributyltin) propanoic hydrazide, 3- (trimethyltin) propanoic hydrazide, 3- (triphenyltin) propanoic hydrazide, and 3- (trioctyltin) propanoic acid. Hydrazide, 4- (tributyltin) butanoic hydrazide, 4- (trimethyltin) butanoic hydrazide, 4- (triphenyltin) butanoic hydrazide, 4- (trioctyltin) butanoic hydrazide, 2- (tributyltin) benzohydrazide , 4- (tributyltin) benzohydrazide, 2- (trimethyltin) benzohydrazide, 4- (trimethyltin) benzohydrazide, 2- (trioctyltin) benzohydrazide, 4- (trioctyltin) benzohydrazide, etc. Hydrazide compound You can list things. These tin-containing hydrazide compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the step of adding the polar group-containing hydrazide compound include a step of adding the polar group-containing hydrazide compound solution to the solid natural rubber raw material after drying using a mixer, an extruder, a kneader, etc. From the viewpoint of improving dispersibility, it is preferable to mix with a kneader. Further, a strainer treatment may be performed after the kneading. Thereby, a modified natural rubber having a high molecular weight and less dust is obtained. Here, the “strainer treatment” refers to a treatment for removing dust contained in the modified natural rubber using a mesh member.

  In the step of adding the polar group-containing hydrazide compound, the polar group-containing hydrazide compound may be added as it is, or may be added as a polar group-containing hydrazide compound solution or an emulsion solution diluted with a solvent. From the viewpoint of improving dispersibility in natural rubber, it is preferably added as a hydrazide compound solution or an emulsion solution.

  The polar group-containing hydrazide compound solution is obtained by diluting a hydrazide compound with a solvent, and a suitable solvent type is set depending on the type of hydrazide compound. Water (purified water, ion exchange water, pure water, etc.) can be used as the solvent species. The polar group-containing hydrazide compound emulsion can be obtained by a usual method using an emulsifier and, if necessary, an affinity agent. Here, the concentration of the aqueous solution of the polar group-containing hydrazide compound is preferably 20 to 80% by mass, and the concentration of the polar group-containing hydrazide compound emulsion is preferably 3 to 50% by mass. If the concentration of the polar group-containing hydrazide compound in the aqueous solution or the emulsion is too low (the concentration of the aqueous solution is 20% by mass or the concentration of the emulsion is less than 3% by mass), a desired amount of the polar group-containing hydrazide compound is obtained. If the amount of the aqueous solution or emulsion required to be added is too large and the concentration of the polar group-containing hydrazide compound is too high (the concentration of the aqueous solution exceeds 80% by mass or the concentration of the emulsion exceeds 50% by mass) ), The stability of the solution is lowered, and there are cases where problems such as a decrease in the dispersibility of the polar group-containing hydrazide compound occur.

  The addition amount of the polar group-containing hydrazide compound aqueous solution is preferably in the range of 0.05 to 30% by mass, more preferably in the range of 1 to 10% by mass with respect to the total amount of natural rubber, and the addition of the polar group-containing hydrazide compound emulsion The amount is preferably in the range of 0.05 to 30% by mass, more preferably in the range of 1 to 10% by mass, based on the total amount of natural rubber. Moreover, the addition amount of a polar group containing hydrazide compound has the preferable range of 0.01-8.0 mass parts with respect to 100 mass parts of solid rubber components in the said natural rubber raw material. When the modified natural rubber is blended with fillers such as carbon black and silica, considering the purpose of improving low loss characteristics and wear resistance without reducing processability, each molecule of natural rubber Since it is important that a small amount of polar groups are introduced, the amount of addition of the polar group-containing hydrazide compound in the modified natural rubber is 0.01 to 5.0 mass based on the solid rubber component in the natural rubber raw material. % Is preferable, and 0.01 to 2.0 mass% is more preferable.

[(B) Carbon black for rubber compounding]
Next, the carbon black for rubber compounding as component (B), which is an essential component of the rubber composition of the present invention, will be described in detail.
The rubber composition of the present invention uses a reaction apparatus in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, generates high-temperature combustion gas in the combustion gas generation zone, and then the reaction After the raw material is sprayed and introduced into the zone to form a reaction gas stream containing carbon black, the reaction gas stream is quenched in the reaction stop zone by means of a multistage rapid refrigerant introduction means to terminate the reaction. The carbon black for rubber compounding is included.

(Method for producing carbon black for rubber compounding)
The manufacturing method of carbon black for rubber | gum mixing used for the rubber composition of this invention is demonstrated.
The interior of the carbon black production furnace has a structure in which a combustion zone, a reaction zone, and a reaction stop zone are connected, and the whole is covered with a refractory.
The carbon black production furnace uses a rectifying plate to rectify the oxygen-containing gas introduced from the outer periphery of the furnace head and the oxygen-containing gas introduction pipe into the flammable fluid introduction chamber as a combustion zone. An oxygen-containing gas introduction cylinder to be introduced, and a fuel oil spraying device introduction pipe installed on the central axis of the oxygen-containing gas introduction cylinder and introducing the hydrocarbon for fuel into the combustible fluid introduction chamber. In the combustion zone, high-temperature combustion gas is generated by combustion of hydrocarbons for fuel.

  The carbon black production furnace includes a reaction chamber in which a cylinder gradually converges, a raw material oil introduction chamber including, for example, four raw oil spray ports on the downstream side of the convergence chamber, and a reaction chamber on the downstream side of the raw material oil introduction chamber. With. The feed oil spray port sprays feed hydrocarbons into the hot combustion gas stream from the combustion zone. In the reaction zone, the raw material hydrocarbon is sprayed into the high-temperature combustion gas stream, and the raw material hydrocarbon is converted into carbon black by incomplete combustion or thermal decomposition reaction.

FIG. 1 is a partially longitudinal front explanatory view of an example of a carbon black production furnace for producing the rubber compounding carbon black, in which a high-temperature gas containing a carbon black raw material (raw material hydrocarbon) is introduced. The chamber 10 and the reaction continuation / cooling chamber 11 are shown. As shown in FIG. 1, the carbon black production furnace 1 includes a reaction continuation / cooling chamber 11 having a multistage rapid refrigerant introduction means 12 as a reaction stop zone. The multistage rapid refrigerant introduction means 12 sprays a rapid refrigerant such as water on the high-temperature combustion gas flow from the reaction zone. In the reaction stop zone, the high-temperature combustion gas flow is quenched by the quenching refrigerant to terminate the reaction.
The carbon black production furnace 1 may further include a device for introducing a gas body in the reaction zone or the reaction stop zone. Here, as the “gas body”, air, a mixture of oxygen and hydrocarbon, a combustion gas obtained by a combustion reaction thereof, or the like can be used.
In this way, in the production of carbon black, the average reaction temperature and residence time in each zone until the reaction gas flow enters the reaction stop zone are controlled, and the toluene color permeability X, Y and Z are set to desired values. Thus, carbon black for rubber compounding used in the rubber composition of the present invention is obtained.

Here, each band in the present invention will be described.
The combustion zone is a region where a high-temperature gas flow is generated by the reaction of fuel and air, and this downstream end is the point at which the feedstock is introduced into the reactor (the most upstream when introduced at multiple locations) ), For example, the upstream side (left side in FIG. 1) from the point where the feedstock is introduced.
The reaction zone refers to the multistage quench water spray means 12 in the reaction continuation / cooling chamber 11 from the point where the raw material hydrocarbon is introduced (the most upstream in the case of a plurality of positions) (these means are the reaction continuation / cooling chamber). 11 can be inserted and removed freely, and the use position is selected according to the type of product to be produced and the characteristics thereof) to the point of operation (introducing a cooling medium such as water). That is, for example, when the raw material oil is introduced at the third raw material oil spray port and water is introduced by the multistage rapid refrigerant introduction means 12, the region between these becomes the reaction zone. The reaction stop zone refers to a zone below (on the right side in FIG. 1) the point where the quenching water injection spray means is operated.
In FIG. 1, the name of the reaction continuation / cooling chamber 11 is used because the reaction zone is from the raw material introduction time point to the operation time point of the quenching water injection spray means for stopping the reaction, and the reaction stop zone is thereafter. This is because the cold water introduction position may move depending on the required carbon black performance.

[Properties of carbon black for rubber compounding]
In the present invention, the carbon black for rubber blending obtained as described above has the following relational expressions (1) and (2):
10 <X <40 (1)
90 <Z <100 (2)
It is necessary to satisfy.
X represents the toluene coloring permeability (%) of carbon black after the rapid refrigerant introduction from the first rapid refrigerant introduction means (12-X in FIG. 1) from the raw material introduction position, and Z represents the last Shows the toluene-colored permeability (%) of carbon black after the rapid refrigerant body is introduced by the rapid refrigerant body introducing means (12-Z in FIG. 1). That is, the carbon black after introduction of the first rapid refrigerant body has a toluene coloring permeability higher than 10% and less than 40%, and the carbon black after introduction of the final rapid refrigerant body (carbon black for rubber blending) is The toluene color transmission needs to be higher than 90% and lower than 100%. If the toluene color permeability of the carbon black for rubber blending is 90% or less, the carbon black has a lot of heavy tar components contained therein, and gives sufficient reinforcement to the rubber. Can not be done, and wear resistance is reduced.
Further, when X is 40 or more, the reinforcing property of the carbon black is lowered and the wear resistance is lowered.

The rubber compounding carbon black having such properties can be obtained by controlling the reaction temperature and residence time as described below.
That is, the residence time in the zone from when the raw material is sprayed into the reaction zone until the first quenching medium is introduced is t ₁ (seconds), and the average reaction temperature in this zone is T ₁ (° C.). And the residence time in the zone from the introduction of the first quenching medium to the introduction of the quenching medium by the second quenching medium introducing means (12-Y in FIG. 1) is t ₂ (seconds). The average reaction temperature in this zone is T ₂ (° C.), and the residence time in the zone from the introduction of the second sudden refrigerant body to the introduction of the last sudden refrigerant body (ie, the reaction stop zone) When the residence time in the zone until passage is t ₃ (seconds) and the average reaction temperature in this zone is T ₃ (° C.), the following relational expressions (3), (4) and (5)
2.00 ≦ α1 ≦ 5.00 (3)
5.00 ≦ α2 ≦ 9.00 (4)
−2.5 × (α1 + α2) + 85.0 ≦ β ≦ 90.0 (5)
(However, α1 = t ₁ × T ₁ , α2 = t ₂ × T ₂ , β = t ₃ × T _3. )
The carbon black for rubber | gum compounding can be obtained by controlling so that it may satisfy | fill.

The carbon black production furnace 1 has a structure in which thermocouples can be inserted into an arbitrary number of locations in order to monitor the temperature in the furnace. To calculate the average reaction temperature T _1, T _2, T _3, at each step (each band), at least two positions, preferably it is preferable to measure the temperature of 3-4 points.
Further, the residence times t ₁ , t ₂ , and t ₃ are calculated by calculating the volume of the introduced reaction gas fluid by a known thermodynamic calculation method, and calculating by the following equation. Note that the increase in volume due to the decomposition reaction of the feedstock oil and the rapid cooling medium is ignored.
Residence time t ₁ (sec) =
{Reactor passing volume from raw material hydrocarbon introduction position to first quenching medium introduction position (m ³ ) / reactive gas fluid volume (m ³ / sec)}
Residence time t ₂ (sec) =
{Reactor passing volume (m ³ ) / reaction gas fluid volume (m ³ / sec) from introduction of first quenching medium to introduction of second quenching medium}
Residence time t ₃ (sec) =
Reactor passing volume (m ³ ) / reaction gas fluid volume (m ³ / sec) from the second quenching medium introduction position until the last quenching medium is introduced

Further, as the carbon black for rubber compounding, the following relational expressions (6), (7) and (8)
20 <X <40 (6)
50 <Y <60 (7)
90 <Z <95 (8)
(In the formula, Y represents the toluene coloring permeability of carbon black after introduction of the second quenching medium, and X and Z are the same as described above.)
What was obtained by controlling to satisfy | fill can be used suitably.
The toluene coloring transmittance is measured by the method described in Method B of Item 8 of JIS K 6218: 1997, and is expressed as a percentage with pure toluene.

The carbon black for rubber blending preferably has a hydrogen release rate exceeding 0.3% by mass. When this hydrogen release rate exceeds 0.3% by mass, the rubber composition of the present invention has high wear resistance and low heat generation. The hydrogen release rate is preferably 0.35% by mass or more. The upper limit is usually about 0.4% by mass.
The hydrogen release rate is as follows: (1) a carbon black sample is dried in a constant temperature dryer at 105 ° C. for 1 hour, cooled to room temperature in a desiccator, and (2) about 10 mg is added to a tubular tube sample container made of tin. Weigh accurately, crimp and seal, and (3) measure the amount of hydrogen gas generated when heated at 2000 ° C for 15 minutes under an argon stream with a hydrogen analyzer (Horiba EMGA621W), and display the mass fraction. .

Further, the carbon black for rubber blending has a dibutyl phthalate absorption (DBP) of 95 to 220 mL / 100 g, a compressed DBP absorption (24M4DBP) of 90 to 200 mL / 100 g, and a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 70. What is -200 m < ² > / g is preferable.
The dibutyl phthalate absorption amount (DBP) and the compressed DBP absorption amount (24M4DBP) are measured by the method described in ASTM D2414-88 (JIS K6217-4: 2001) and are absorbed per 100 g of carbon black. DBP) in mL. Further, the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is measured by the method described in JIS K6217-3: 2001 and is expressed as a specific surface area m ² / g per unit mass of carbon black.

[Rubber composition]
The rubber composition of the present invention needs to contain (B) the above-described rubber compounding carbon black at a ratio of 10 to 250 parts by mass with respect to 100 parts by mass of the rubber component containing (A) the modified natural rubber.
When the content of the carbon black is less than 10 parts by mass, the reinforcing effect of the rubber composition is not sufficiently exhibited, and desired wear resistance cannot be obtained. On the other hand, when it exceeds 250 parts by mass, a rubber composition having desired physical properties such as low rolling resistance cannot be obtained. The content of the carbon black as the component (B) is preferably 20 to 150 parts by mass, and more preferably 30 to 120 parts by mass with respect to 100 parts by mass of the (A) rubber component.
The carbon black for rubber compounding as the component (B) is manufactured by the above-described method and has the above-described physical properties. Examples of the carbon black include FEF, SRF, HAF, ISAF, ISAF. -LS, SAF-LS and the like.

(Other rubber components)
The other rubber components contained in the rubber component include at least one selected from conjugated diene rubbers such as natural rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, synthetic isoprene rubber, ethylene-propylene-diene rubber, chloroprene rubber. It is preferable that all rubber components are conjugated diene rubbers.
In the present invention, it is necessary that the rubber component contains the above-mentioned (A) modified natural rubber which is modified with a modifier comprising a compound containing a functional group that interacts with carbon black in at least one molecule. It is. This further improves the wear resistance and low rolling resistance of the resulting rubber composition.

(Preparation of rubber composition)
In the rubber composition of the present invention, in addition to (A) the rubber component containing modified nature and (B) the carbon black for blending rubber, other components such as inorganic filler, vulcanizing agent, vulcanization accelerator, zinc oxide The compounding agents usually used in the rubber industry such as stearic acid and anti-aging agent can be appropriately selected and blended within a range not impairing the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition comprises (A) a rubber component containing modified nature, (B) carbon black for compounded rubber, and various appropriately selected compounding agents, and a Banbury mixer, roll, internal mixer, It can be prepared by kneading using an intensive mixer or the like, followed by heating, extruding, or the like.

[tire]
The tire of the present invention is characterized in that the rubber composition is applied to any of tire members. Here, in the tire of the present invention, it is particularly preferable to use the rubber composition of the present invention for a tread. The tire using the rubber composition for a tread has excellent wear resistance and low rolling resistance and low fuel consumption. Also excellent in properties. In addition, as gas with which the tire of the present invention is filled, normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen is exemplified. When the rubber composition of the present invention is used for a tread, for example, it is extruded on a tread member, and is pasted and molded by a usual method on a tire molding machine to form a raw tire. The green tire is heated and pressed in a vulcanizer to obtain a tire.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
The tire wear resistance and rolling resistance were evaluated according to the following methods.
(1) Abrasion resistance Using a Lambourn-type wear tester, the amount of wear at a slip rate of 60% in the room was measured, and the index was displayed as Comparative Example 1 in Table 4 and Comparative Example 3 in Table 5. . The higher the index, the better the wear resistance.
(2) Rolling resistance Using a viscoelasticity measuring device (manufactured by Rheometric Co., Ltd.), tan δ (50 ° C.) was measured at a temperature of 50 ° C., a strain of 5%, and a frequency Hz. In the table, Comparative Example 3 was set as 100 and indicated as an index. The smaller the index, the lower the heat buildup.
Further, the toluene coloring permeability, hydrogen release rate, DBP absorption amount, 24M4DBP absorption amount and CTAB adsorption specific surface area of carbon black were measured according to the methods described in the specification.

Production Example 1
(1) Modification process of natural rubber latex The field latex was centrifuged at a rotation speed of 7500 rpm using a latex separator (manufactured by Saito Centrifugal Co., Ltd.) to obtain a concentrated latex having a dry rubber concentration of 60%. 1000 g of this concentrated latex was put into a stainless steel reaction vessel equipped with a stirrer and a temperature control jacket, and 10 ml of water and 90 mg of emulsifier (Emulgen 1108, manufactured by Kao Corporation) were added in advance to N, N-diethylaminoethyl methacrylate. What was added and emulsified in addition to 0 g was added together with 990 ml of water, and these were stirred for 30 minutes while purging with nitrogen. Next, 1.2 g of tert-butyl hydroperoxide and 1.2 g of tetraethylenepentamine were added as polymerization initiators and reacted at 40 ° C. for 30 minutes to obtain a modified natural rubber latex.

(2) Coagulation and drying step The modified natural rubber latex was coagulated by adding formic acid and adjusting the pH to 4.7. The solid thus obtained was treated 5 times with a creper, passed through a shredder to crumb, and dried at 110 ° C. for 210 minutes with a hot air dryer to obtain modified natural rubber A. From the weight of the modified natural rubber A thus obtained, it was confirmed that the conversion rate of N, N-diethylaminoethyl methacrylate as a polar group-containing monomer was 100%. Further, when the homopolymer was separated by extracting the modified natural rubber A with petroleum ether and further extracting with a 2: 1 mixed solvent of acetone and methanol, the homopolymer was not detected from the analysis of the extract, It was confirmed that 100% of the added monomer was introduced into the natural rubber molecule. Table 1 shows the addition amount of monomer N, N-diethylaminoethyl methacrylate and the addition amount (% by mass) with respect to natural rubber.

Production Example 2
A modified natural rubber B was obtained by carrying out the same treatment as in Production Example 1, except that 1.7 g of 4-vinylpyridine was used instead of 3.0 g of N, N-diethylaminoethyl methacrylate. When the modified natural rubber B was analyzed by the same method as in Production Example 1, it was confirmed that 100% of the added monomer was introduced into the natural rubber molecule. The amount of monomer 4-vinylpyridine added and the amount added (% by mass) to natural rubber are shown in Table 1.

Production Example 3
The pH was adjusted to 4.7 by adding formic acid to the field latex and coagulated. This solid was treated 5 times with a creper and crushed through a shredder. After determining the dry rubber content of this coagulated product, 600 g of the coagulated product and an emulsion solution of 3.0 g of isonicotinohydrazide in terms of dry rubber were kneaded for 2 minutes at 30 rpm in a kneader (prebreaker) at room temperature. A modified natural rubber C obtained by drying, uniformly dispersing and drying was obtained. Further, the unreacted hydrazide compound was separated by extracting the modified natural rubber C with petroleum ether and further extracting with a 2: 1 mixed solvent of acetone and methanol. No hydrazide compound was detected, and therefore the amount of isonicotinohydrazide added in the modified natural rubber A was 0.5% by mass relative to the solid rubber component in the natural rubber raw material. Table 1 shows the amount of hydrazide compound isonicotinohydrazide added and the amount added (% by mass) to natural rubber.

Production Example 4
Modified natural rubber D was obtained in the same manner as in Production Example 3 except that 3.5 g of phthalic hydrazide was added instead of 3.0 g of isonicotinohydrazide. Similarly to the modified natural rubber C, the addition amount of the polar group-containing hydrazide compound in the modified natural rubber D was analyzed. Table 1 shows the amount of phthalic hydrazide added and the amount added (% by mass) based on natural rubber.

Production Comparative Example 1
Natural rubber O was obtained in the same manner as in Production Example 3 except that isonicotinohydrazide was not added.

Production Example 5 Production of Carbon Black a Carbon black a was produced using the carbon black production furnace shown in FIG. However, in FIG. 1, as the multistage rapid refrigerant introduction means 12, a three-stage comprising a first rapid refrigerant introduction means 12-X, a second rapid refrigerant introduction means 12-Y, and a final rapid refrigerant introduction means 12-Z. The rapid refrigerant introduction means was used.
Moreover, in order to monitor the temperature in a manufacturing furnace, the said manufacturing furnace provided with the structure where a thermocouple can be inserted in a furnace in arbitrary several places was used. In the carbon black production furnace, A heavy oil having a specific gravity of 0.8622 (15 ° C./4° C.) was used as the fuel, and heavy oil having the properties shown in Table 2 was used as the feed oil. Table 3 shows the operating conditions of the carbon black production furnace and the characteristics of the carbon black.

Production Examples 6 to 7 Production of carbon blacks b and c Carbon blacks b to c were produced in the same manner as in Production Example 4 except that the operating conditions shown in Table 3 were employed. Table 3 shows the characteristics of each carbon black.

Examples 1-8 and Comparative Examples 1-2
Examples 1 to 8 used the modified natural rubbers A to D shown in Table 1, and the carbon blacks b and c shown in Table 3 were used for carbon black. In accordance with the description in Table 4, the combination of the two was prepared by using a Banbury mixer to prepare 8 types of rubber compositions having the formulation of rubber composition 1 shown in Table 6.
Comparative Examples 1 and 2 used each modified natural rubber O shown in Table 1. Carbon black a and b shown in Table 3 were used for carbon black. In accordance with the description in Table 4, two combinations were prepared by using a Banbury mixer to prepare two types of rubber compositions having the formulation of rubber composition 1 shown in Table 6.

Examples 9-16 and Comparative Examples 3-4
In Examples 9 to 16, the modified natural rubbers A to D shown in Table 1 were used, and the carbon blacks b and c shown in Table 3 were used for the carbon black. The combinations of the two were prepared according to the description in Table 5, and eight kinds of rubber compositions having the compounding formulation of the rubber composition 2 shown in Table 6 were prepared by a Banbury mixer.
In Comparative Examples 3 to 4, the modified natural rubber O shown in Table 1 was used, and for the carbon black, carbon blacks a and b shown in Table 3 were used. In accordance with the description in Table 5, two combinations of the two rubber compositions of the rubber composition 2 blended formulation shown in Table 6 were prepared using a Banbury mixer.
Next, these 20 kinds of rubber compositions were vulcanized by a conventional method to prepare samples for evaluation tests, and the rolling resistance and wear resistance were evaluated. The results are shown in Tables 4 and 5.

［注］
１）天然ゴム：製造実施例１〜４、及び製造比較例１で得た天然ゴム
２）ポリブタジエンゴム：宇部興産（株）製、商品名「ＵＢＥＰＯＬ−ＢＲ１５０Ｌ」（ビニル結合含有量：１％、重量平均分子量（Ｍｗ）：５２０，０００）
３）カーボンブラック：製造実施例５〜７で得たカーボンブラック
４）老化防止剤６Ｃ：Ｎ−（１，３−ジメチルブチル）−Ｎ’−フェニル−ｐ−フェニレンジアミン、大内新興化学工業社製、商品名「ノクラック６Ｃ」
５）加硫促進剤ＣＺ：Ｎ−シクロヘキシル−２−ベンゾチアジルスルフェンアミド、大内新興化学工業社製、商品名「ノクセラーＣＺ」

[note]
1) Natural rubber: Natural rubber obtained in Production Examples 1 to 4 and Production Comparative Example 1 2) Polybutadiene rubber: Ube Industries, Ltd., trade name “UBEPOL-BR150L” (vinyl bond content: 1%, Weight average molecular weight (Mw): 520,000)
3) Carbon black: carbon black obtained in Production Examples 5 to 7 4) Anti-aging agent 6C: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, Ouchi Shinsei Chemical Co., Ltd. Product name "NOCRACK 6C"
5) Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “Noxeller CZ”

  From Tables 4 and 5, Examples using carbon black and modified natural rubber satisfying the production conditions and physicochemical properties of carbon black defined in the present invention are rolling resistance and wear resistance compared to Comparative Examples. It can be seen that both of these performances are significantly improved and highly balanced.

  The rubber composition of the present invention contains a carbon black having a specific property obtained by a specific process as a filler and a modified natural rubber having a specific structure as a rubber component at a predetermined ratio, thereby providing a high resistance. A tire with a high balance between wear and low heat generation (low rolling resistance) can be provided.

DESCRIPTION OF SYMBOLS 1 Carbon black production furnace 10 Reaction chamber 11 Reaction continuation and cooling chamber 12 Multistage rapid refrigerant body introduction means 12-X First rapid refrigerant body introduction means 12-Y Second rapid refrigerant body introduction means 12-Z Last rapid refrigerant body introduction means

Claims (7)

Using a reactor in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected in series, high temperature combustion gas is generated in the combustion gas generation zone, and then a raw material is sprayed into the reaction zone. After forming a reaction gas stream containing carbon black, a carbon black for rubber compound obtained by quenching the reaction gas stream by a multistage rapid refrigerant introduction means in the reaction stop zone and terminating the reaction is obtained. And a rubber composition containing a modified natural rubber in which a polar group-containing compound is added to natural rubber as a rubber component,
(1) The carbon black for rubber blending has the following relational expressions (1) and (2):
10 <X <40 (1)
90 <Z <100 (2)
(However, X represents the toluene coloring permeability (%) of carbon black after introduction of the first quenching medium from the raw material introduction position, and Z represents the toluene coloring permeability of carbon black after the last quenching medium introduction ( And (2) (B) the carbon black for rubber compounding in a proportion of 10 to 250 parts by mass with respect to 100 parts by mass of the rubber component containing (A) the modified natural rubber. A rubber composition characterized by comprising.   The rubber composition according to claim 1, wherein an addition amount of the polar group-containing compound is 0.01 to 5.0% by mass with respect to the natural rubber.   The polar group of the polar group-containing compound is amino group, imino group, nitrile group, ammonium group, imide group, amide group, hydrazo group, azo group, diazo group, hydroxyl group, carboxyl group, carbonyl group, epoxy group, oxycarbonyl The rubber composition according to claim 1 or 2, which is at least one selected from the group consisting of a group, a nitrogen-containing heterocyclic group, an oxygen-containing heterocyclic group, and a tin-containing group.   The rubber composition according to claim 1, wherein the polar group-containing compound is a polar group-containing monomer, and the modified natural rubber into which the monomer is grafted by emulsion polymerization and the polar group-containing compound is introduced is used.   The rubber composition according to claim 1, wherein the polar group-containing compound is a modified natural rubber which is a polar group-containing hydrazide compound.   The rubber composition according to any one of claims 1 to 5, comprising (A) a modified natural rubber in a proportion of 10% by mass or more in 100 parts by mass of the rubber component. A tire using the rubber composition according to claim 1.

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