JP2007224069A - Rubber composition and pneumatic tire using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition suitably used in a heavy-duty pneumatic tire and an off-road tire and having excellent low heat build-up properties and good operation efficiency and to provide the pneumatic tire using the rubber composition. <P>SOLUTION: The rubber composition is obtained by compounding at least one kind of rubber component selected from the group consisting of natural rubber and synthetic rubbers with a compound having a moiety Q containing one or more dipolar nitrogens represented by A1-C(A2)=N(A3)→O, A1-C≡N→O and A1-C≡N→N-A4 (wherein, A1 to A4 are each a hydrogen or a ≤20C group or a linking group to B) and a moiety B containing a 4- to a 6-membered nitrogen-containing heterocycle containing an oxygen or a sulfur and silica and simultaneously including a partial ester compound of maleic acid with an oxypropylene derivative or a polyoxypropylene derivative. The pneumatic tire is prepared by using the rubber composition in a tire member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a rubber composition and a pneumatic tire using the rubber composition. More specifically, the present invention relates to a demanding heavy load pneumatic tire and an off tire which improve heat resistance in a tread and improve wear resistance. The present invention relates to a rubber composition suitable for use in a road tire and a pneumatic tire using the same.

In general, a pneumatic tire requires low fuel consumption and stability of an automobile. In particular, heavy duty pneumatic tires used for trucks, buses and the like are required to have further improved heat generation. Further, for off-road tires, the tread rubber is required to have low hysteresis loss (low rolling resistance) and wear resistance. In general, in order to improve low heat generation, it is preferable to suppress the deformation of the tread rubber and lower tan δ in a high temperature range.
Particularly for off-road tires, in order to improve wear resistance, synthetic rubber components such as SBR have been used in the tread rubber composition to improve cutability and fatigue resistance. In order to improve low hysteresis loss and low heat generation, it has also been proposed to add a modified conjugated diene polymer such as a modified styrene-butadiene copolymer (see, for example, Patent Document 1). . However, if the amount of the modified conjugated diene polymer is excessively increased, the wear resistance cannot be sufficiently improved, and the fracture resistance is deteriorated.

Conventionally, silica is known as a filler for improving low heat build-up (for example, Patent Documents 2 to 9). However, in order to improve the dispersion of the silica in the rubber, it is necessary to lengthen the kneading time, and the viscosity increases and the workability deteriorates. Furthermore, low heat build-up and a decrease in elastic modulus occur due to reversion after long-term vulcanization, making it difficult to blend a large amount of silica.
Therefore, in combination with a synthetic rubber such as SBR and its modified rubber, after improving to some extent, silica is added to improve low heat build-up, and further, the elastic modulus does not decrease. There is a need for off-road tires.
Japanese Patent Laid-Open No. 9-316132 JP-A-3-252431 JP-A-6-248116 JP-A-7-70369 JP-A-7-188466 JP-A-7-196850 JP-A-8-225684 JP-A-8-245838 JP-A-8-337687

  In view of the above problems, the present invention provides a rubber composition that achieves both wear resistance and low heat buildup suitable as a heavy-duty pneumatic tire and off-road tire without impairing workability during tire manufacture, and the same It is to provide a pneumatic tire using the tire.

In order to solve the above-mentioned problems, the present inventors, in a rubber composition filled with silica, a part containing dipolar nitrogen that exhibits reactivity at a double bond site such as a rubber component, and carbon black, A composition comprising a compound containing a nitrogen-containing heterocyclic ring containing oxygen or sulfur that is reactive with a filler such as silica filler, and a partial ester of maleic acid and a (poly) oxypropylene derivative When blended in, the dispersibility of carbon black and silica is enhanced, and the low exothermic property of the rubber composition is further improved, and the workability is deteriorated by suppressing the increase in viscosity due to gelation during the kneading operation of the rubber composition. The present inventors have found that this is not the case and have arrived at the present invention.
That is, the present invention is characterized by the following means or configurations.

(1) For 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber and synthetic rubber, a part Q containing dipolar nitrogen and 4-6 nitrogen-containing heterocycles containing oxygen or sulfur Compound D having 0.1 to 30 parts by mass of Compound D having a part B containing N and 0.1 to 10 parts by mass of partial ester compound M of maleic acid and a (poly) oxypropylene derivative. A rubber composition obtained by using the rubber composition as a tire member.

(2) The dipolar nitrogen portion Q of the compound D is at least one of A1-C (A2) = N (A3) → O, A1-C≡N → O, and A1-C≡N → N-A4. Wherein A1 to A4 may be different from each other, hydrogen or a group having 20 or less carbon atoms or a linking chain connecting the B, and the compound is at least one of A1 to A4 and the B is The rubber composition according to the above (1), which is a linked compound.
(3) A1 to A4 of the compound D are hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms (provided that the aromatic ring has a nitro group) , A cyano group, a chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group), or a group thereof selected from the above ( 2) The rubber composition as described.
(4) The rubber composition according to the above (1), wherein the nitrogen-containing heterocyclic ring at the B portion of the compound D is oxazoline or thiazoline.

(5) The above compound D is 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, 4- (2-oxazolyl) -phenyl- N-phenyl-nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2-thiazolyl)- Phenyl-nitrone, 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- ( 2-Oxazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -phenyl-nitrile Xoxide, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrileimine, 4 -(2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl-N- The rubber composition according to the above (4), which is one or more selected from 4- (2-oxazolyl) -phenyl-nitrileimine and phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine.

(6) The rubber composition as described in any one of (1) to (5) above, wherein the rubber composition used for the pneumatic tire further contains 0.1 to 5.0 parts by mass of the hydrazide compound Z. .
(7) The rubber composition as described in any one of (1) to (6) above, which contains 50 parts by mass or more of natural rubber in 100 parts by mass of the rubber component in the rubber composition used for the pneumatic tire. .
(8) Any of (1) to (7) above, wherein the silica content in the rubber composition used for the pneumatic tire is 2 to 50 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition according to one.
(9) A pneumatic tire using the rubber composition according to any one of (1) to (8) as a tire member.
(10) The pneumatic tire according to (9), wherein the pneumatic tire is a heavy duty pneumatic tire.
(11) The pneumatic tire according to (10), wherein the heavy-duty pneumatic tire is an off-road tire.

According to the above means, the wear resistance and low heat build-up can be improved, the tire can be improved, and the workability is not deteriorated due to the increase in viscosity.
Moreover, when said compound D is added, the reaction of following reaction formula (1)-(3) will arise with the double bond part (P) in a rubber component, and Q part of a compound.

  Furthermore, the reaction of the following reaction formulas (4) to (15) occurs between the carbon black (CB) or silica filler and the B portion of the compound D.

  Due to the action of such a compound, carbon black and silica are sufficiently diffused in the rubber composition. As a result, in addition to wear resistance, the low heat build-up and low hysteresis loss of the tread rubber are further improved, and the use performance as a heavy duty pneumatic tire and off-road tire is further enhanced.

Hereinafter, embodiments of the present invention will be described in detail.
The rubber component of the rubber composition of the present invention is at least one selected from natural rubber and diene synthetic rubber. Examples of the diene synthetic rubber include polyisoprene synthetic rubber (IR) and polybutadiene rubber (BR). Styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and the like. This rubber component natural rubber or diene-based synthetic rubber may be used alone or in combination of two or more, and preferably contains 50% by mass of the natural rubber in the rubber component.

  In the rubber composition, carbon rubber and silica are blended with the rubber component. These are preferably blended in the range of 30 to 100 parts by mass with respect to 100 parts by mass of the rubber component, and the blending amount of silica is preferably 2 to 50 parts by mass. As the amount of carbon black and silica decreases, the elastic modulus tends to decrease. Moreover, when the amount of carbon black or the like increases, the low exothermic property of the vulcanized rubber composition tends to deteriorate.

Silica having a nitrogen adsorption specific surface area (N ₂ SA) in the range of 180 to 270 m ² / g is preferably used. If the specific surface area is less than 180 m ² / g, the wear resistance may be insufficient. On the other hand, if it exceeds 270 m ² / g, a dispersion failure will occur and the low heat build-up, wear resistance and workability will be significantly reduced. It becomes. Additional nitrogen adsorption specific surface area (N ₂ SA) after 1 hour drying at 300 ° C., a value measured in conformity with ASTM D4820-93.
Examples of such silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Of these, wet silica is particularly preferred.

  Carbon black can be appropriately selected from those usually used in the rubber industry, and examples thereof include SAF, SRF, GPF, FEF, HAF, and ISAF. In addition, it is desirable to activate the surface of carbon black or the like using oil absorption.

  In the rubber composition of the present invention, the compound D having a part Q containing a dipolar nitrogen and a part B containing 4 to 6 nitrogen-containing heterocycles containing oxygen or sulfur with respect to 100 parts by mass of the rubber component is reduced to 0.0. It mix | blends 1-30 mass parts, It is characterized by the above-mentioned.

  The above compound D is a compound of the present invention as long as it contains a dipolar nitrogen moiety. Specific examples of particularly preferred dipolar nitrogen moieties include A1-C (A2) = N (A3) → O (nitrone system), A1-C≡N → O (nitrile oxide system), and A1-C≡. N → N-A4 (nitrile imine type) can be mentioned. These dipolar nitrogen portions Q are reactively bonded to double bond portions in a polymer such as a rubber component as shown in the above reaction formulas (1) to (3).

The groups A1 to A4 in the nitrone-based, nitrile oxide-based, and nitrileimine-based dipolar nitrogen portions Q are preferably hydrogen, a group having 20 or less carbon atoms, or a connecting chain. When the number of carbon atoms exceeds 20, the molecular weight of the compound itself increases, and the reactivity with the rubber component becomes worse.
Since the compound D has a B portion, A1 to A4 can be a connecting chain that connects the B portions. However, in the case of A1 to A3, in the case of only A1, or in the case of A1 and A4, at least one or more are connected to the B portion, and a plurality of B portions may exist. A1 to A4 may be different or the same.

  Specific groups or connecting chains of A1 to A4 of the above compound D include hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms (provided that The aromatic ring may have a nitro group, a cyano group, a chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group), or a group selected from them The connecting chain. The alkyl group, acyl group, carbonylalkyl group, and alkoxyl group may have a branched chain or a cyclo ring. A1 to A4 may be different from each other.

The B portion of the compound D is composed of a nitrogen-containing heterocycle having oxygen or sulfur such as oxetine, thiozetin, oxazoline, thiazoline, tetrahydrooxazine and tetrahydrothioxazine. In particular, it consists of a 4-6 membered nitrogen-containing heterocyclic ring represented by the following structural formulas (I) to (III) (wherein X is oxygen: O or sulfur: S). Of these, oxazoline and thiazoline of the structural formula (II) are preferable. In each structural formula, R1 to R7 are hydrogen, a group having 20 or less carbon atoms, or a connecting chain. Moreover, in each structural formula similarly to the case of A1 to A4, in the case of R1 to R3, in the case of R1 to R5, or in the case of R1 to R7, at least one or more of A1 to A4 connected to Q Equivalent to.
As described above, the B portion undergoes the binding reaction of the above reaction formulas (4) to (15), and carbon black and silica can be uniformly incorporated into the polymer of the rubber component.

  Specific examples of the compound D include 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, and 4- (2-oxazolyl). -Phenyl-N-phenyl-nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2- Thiazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N- 4- (2-oxazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -fe Ru-nitrile oxide, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrile Imine, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl -N-4- (2-oxazolyl) -phenyl-nitrileimine, phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine and the like can be mentioned.

  Examples of such compounds include 4- (2-oxazolyl) -phenyl-N-methyl-nitrone (hereinafter referred to as 4OPMN) and 4- (2-oxazolyl) -phenyl-N-phenyl-nitrone (hereinafter referred to as 4OPPN). The structural formula is specifically listed.

The method for producing Compound D can be produced without undue experimentation. For example, regarding 4OPMN and 4OPPN, the manufacturing method can be shown in the examples described later.
Further, other compounds D can also be produced by typical production methods by appropriately selecting other starting materials and intermediate materials.

  Said compound D is contained in 0.1-30 mass parts with respect to 100 mass parts of rubber components. Preferably, it is the range of 0.1-5 mass parts, More preferably, it is the range of 0.5-2.0 mass parts. If the compounding amount is less than 0.1, the effects of low heat generation and low hysteresis loss are not sufficient. In addition, if it exceeds 30 parts by mass, an effect commensurate with it cannot be expected, which is preferable from the viewpoint of cost, and when the rubber component is natural rubber, a significant increase in viscosity occurs due to gelation, from the viewpoint of workability. Is also not preferred.

Next, the rubber composition of the present invention includes a partial ester compound M of maleic acid represented by formula (VI) and a (poly) oxypropylene derivative.
HOOCCH = CHCOO (R ^a O) _m R ^b (VI)
In the formula (VI), m represents an average polymerization degree and is a number of 1 or more, R ^a is a propylene group, R ^b is an alkyl group, an alkenyl group, an alkylaryl group or an acyl group.
In the formula (VI), Rb is preferably an alkyl group or alkenyl group having 2 to 28 carbon atoms, more preferably an alkyl group or alkenyl group having 8 to 18 carbon atoms.

The above-mentioned compound M can be obtained by reacting maleic acid or an anhydride thereof and a (poly) oxypropylene derivative.
Examples of the (poly) oxypropylene derivative include a compound having a (poly) oxypropylene group having an average polymerization degree of 1 or more and having one or more hydroxyl groups, preferably having 1 to 2 hydroxyl groups. A compound having a (poly) oxypropylene group, particularly preferably a compound having a (poly) oxypropylene group having one hydroxyl group. Examples of (poly) oxypropylene derivatives include ether types such as (poly) oxypropylene alkyl ether; ester types such as (poly) oxypropylene fatty acid monoester; ether ester types such as (poly) oxypropylene glycerin fatty acid ester; ) Oxypropylene fatty acid amide, nitrogen-containing types such as (poly) oxypropylene alkylamine, and the like are mentioned. As the (poly) oxypropylene derivative used in the present invention, ether type and ester type are preferable, and ether type is particularly preferable. .

Examples of ether type (poly) oxypropylene derivatives include polyoxypropylene lauryl ether, polyoxypropylene decyl ether, polyoxypropylene octyl ether, polyoxypropylene 2-ethylhexyl ether, polyoxypropylene stearyl ether, and polyoxypropylene oleyl ether. Examples include polyoxypropylene aromatic ethers such as saturated and unsaturated aliphatic ethers of polyoxypropylene, polyoxypropylene benzyl ether, polyoxypropylene alkyl phenyl ether, and polyoxypropylene benzylated phenyl ether. Aliphatic ethers are preferred. Furthermore, polyoxypropylene alkyl or alkenyl ether is preferable, and it is particularly preferable that the average degree of polymerization of polyoxypropylene is 1 to 10, and the alkyl group or alkenyl group has 8 to 18 carbon atoms. Specifically, when polyoxypropylene is abbreviated as POP (n) and n is an average degree of polymerization, POP (3) octyl ether, POP (4) 2-ethylhexyl ether, POP (3) decyl ether, POP ( 5) Decyl ether, POP (3) lauryl ether, POP (8) lauryl ether, POP (1) stearyl ether and the like.
Compound M may be used alone or in combination of two or more.

  The said compound M is added in 0.1-10 mass parts with respect to 100 mass parts of rubber components. Preferably it is the range of 0.5-5 mass parts. Compound M has a great effect on the dispersion of silica, and this dispersibility improving effect makes it possible to reduce the viscosity and suppress the increase in viscosity.

In the rubber composition of the present invention, a hydrazide compound Z represented by the following (VII) can be further added.
R ^c -CONHNH ₂ …………… (VII)
(However, R ^c in formula (VII) represents an alkyl group having 1 to 30 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, or an aryl group.)

Examples of the hydrazide compound Z represented by the above formula (VII) include acetohydrazide, propionic acid hydrazide, butyric acid hydrazide, lauric acid hydrazide, palmitic acid hydrazide, stearic acid hydrazide, cyclopropanecarboxylic acid hydrazide, cyclobutanecarboxylic acid hydrazide, Cyclohexanecarboxylic acid hydrazide, cycloheptanecarboxylic acid hydrazide, benzoic acid hydrazide, o-toluic acid hydrazide, m-toluic acid hydrazide, p-toluic acid hydrazide, p-methoxybenzoic acid hydrazide, 3,5-dimethylbenzoic acid hydrazide, lactic acid Examples thereof include hydrazide, phthalic acid hydrazide, and 1-naphthoic acid hydrazide. Among them, fatty acid hydrazide, particularly propionic acid hydrazide is preferable.
The addition amount of the hydrazide compound is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component.

In the rubber composition of the present invention, it is preferable to further add a silane coupling agent in order to reinforce the bond between silica and the rubber component and to maintain and improve low heat buildup and wear resistance.
Examples of the silane coupling agent used for this purpose include bis (3-triethoxysilylpropyl) polysulfide, bis (2-triethoxysilylethyl) polysulfide, bis (3-trimethoxysilylpropyl) polysulfide, and bis ( 2-trimethoxysilylethyl) polysulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-nitropropyltrimethoxysilane, 3 Nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-tripropyl Toxisilylpropyl-N, N-dimethylthiocarbamoyl polysulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl polysulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl polysulfide, 3-trimethoxysilyl Propylbenzothiazole polysulfide, 3-triethoxysilylpropylbenzothiazole polysulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) polysulfide, 3-mercapto Propyldimethoxymethylsilane, 3-nitropropyldimethoxymethylsilane, 3-chloropropyldimethoxymethylsilane, dimethyl Methyl silyl propyl -N, N-dimethylthiocarbamoyl polysulfide, etc. dimethoxymethylsilylpropyl benzothiazole polysulfides and the like.

These may be used alone or in combination of two or more. Among these, bis (3-triethoxysilylpropyl) polysulfide, 3-trimethoxysilylpropylbenzothiazole polysulfide and the like are preferable.
As a compounding quantity of the said silane coupling agent, 5 to 20 weight% is preferable with respect to the compounding quantity of a silica, and 5 to 15 weight% is more preferable.

  The rubber composition containing the above compounds D and M and further Z can reduce the amount of natural rubber polymer gel without decreasing the molecular weight of the natural rubber molecule, and increase the slip between the rubber molecules. This improves the workability of molding and suppresses the deterioration of physical properties of the unvulcanized or vulcanized rubber composition. In addition, when the rubber component does not contain natural rubber, the molding workability is improved by increasing the slip between the rubber molecules, and in this case as well, there is no decrease in the molecular weight of the rubber. The physical properties of the vulcanized rubber composition do not deteriorate. In any case, in the present invention, excellent rubber processability can be obtained without adversely affecting the physical properties of the rubber.

  In addition to the rubber component, silica, carbon black, compound D, compound M, and compound Z, the rubber composition of the present invention can contain various components that are usually used in the rubber industry. Examples include fillers (eg, inorganic fillers such as calcium carbonate and calcium carbonate); vulcanization accelerators; anti-aging agents; zinc oxide; stearic acid; softeners; it can. Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as MBTS (dibenzothiazyl disulfide) and CZ (N-cyclohexyl-2-benzothiazylsulfenamide); TT (tetramethylthiuram sulfide) and the like. Examples include thiuram vulcanization accelerators; and guanidine vulcanization accelerators such as DPG (diphenylguanidine).

  The method for preparing the rubber composition of the present invention is not particularly limited, and the rubber composition can be obtained by kneading the rubber component using an ordinary kneader such as a Banbury mixer, a roll, an intensive mixer or the like.

  Said rubber composition is used suitably for the tread rubber and tread base rubber of a pneumatic tire. A pneumatic tire is manufactured by a normal method using the above rubber composition. That is, if necessary, the rubber composition containing various chemicals as described above is extruded into a tread member, for example, at an unvulcanized stage, and pasted and molded by a usual method on a tire molding machine. A green tire is formed. The green tire is heated and pressed in a vulcanizer to obtain a tire. Since the workability of the rubber composition is good, the productivity is excellent.

  Since the tread portion of the tire contributes greatly to wear resistance and low heat generation, the pneumatic tire of the present invention is a heavy-duty pneumatic tire and an off-road pneumatic tire requiring long-term rough road durability. Can be suitably used. In such a pneumatic tire, an inert gas such as air or nitrogen can be used as a gas to be filled.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
(Examples 1-11 and Comparative Examples 1-6)
The rubber composition of each Example and Comparative Example is shown in Table 1 below, and a rubber composition before crosslinking was prepared using a Banbury mixer according to the formulation table in Table 1 below. A tire of 3700R57 was produced and applied to a tread member.

The compounding amount in Table 1 is part by mass, and in each comment,
* 1) # 1500; Emulsion polymerization SBR
* 2) N ₂ SA; Nitrogen adsorption specific surface area (m ² / g)
* 3) DBP: Dibutyl phthalate oil absorption (ml / 100g)
* 4) Maleic acid monoester; HOOCCH = CHCOO (C ₃ H ₆ O) ₅ C ₁₂ H ₂₅
* 5) 4OPPN; (4- (2-oxazolyl) -phenyl-N-phenylnitrone)
* 6) 4OPMN; (4- (2-oxazolyl) -phenyl-N-methylnitrone)
* 7) Hydrazide compound BMH; Bismaleic acid hydrazide * 8) Anti-aging agent 6C; N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine * 9) Vulcanization accelerator CZ; N-cyclohexyl -2-Benzothiazylsulfenamide

* 5) 4OPPN and * 6) 4OPMN were produced as follows.
<Manufacture of 4OPPN>
To a solution obtained by stirring and mixing 15.0 g of 4-formyl-benzoyl chloride (1 equivalent) in 300 ml of chloroform, a solution obtained by adding 10.9 g of 2-aminoethanol (2 equivalents) to 200 ml of chloroform was added dropwise at −10 ° C. And added. After the solution was placed at 25 ° C. for 2 hours, the white precipitate was removed by filtration. The filtrate was dried by a rotary evaporator to obtain 17.4 g of 4-formyl-N- (2-hydroxyethyl) -benzamide as a yellow liquid.
To 50 ml of concentrated sulfuric acid, 17.4 g of 4-formyl-N- (2-hydroxyethyl) -benzamide was added dropwise with stirring, and the mixture was heated at 100 ° C. for 1 hour. To this solution, 500 ml of 20% sodium hydroxide and chloroform were added dropwise with stirring and mixing, and the temperature was maintained at 15 ° C. or lower. The product layer was separated and dried to give 6.3 g of 4- (2-oxazolyl) -benzaldehyde.
A mixture of 6.3 g (1 equivalent) of 4- (2-oxazolyl) -benzaldehyde and 3.9 g (1 equivalent) of N-phenyl-hydroxyamine was refluxed in 100 ml of ethanol for 30 minutes and concentrated to a volume of 50 ml. . The same amount of 50 ml of water was added and the mixture was cooled to 5 ° C. overnight in a refrigerator. Filtration separation and drying gave white crystals, yielding 6.7 g of 4- (2-oxazolyl) -phenyl-N-phenylnitrone.

<Manufacturing of 4OPMN>
To a solution obtained by stirring and mixing 15.0 g (89 mmol) of 4-formyl-benzoyl chloride in 300 ml of chloroform, a solution obtained by adding 10.9 g (178 mmol) of 2-aminoethanol to 200 ml of chloroform was added dropwise at −10 ° C. . After the solution was placed at 25 ° C. for 2 hours, the white precipitate was removed by filtration. The filtrate was dried by a rotary evaporator to obtain 17 g (88 mmol) of yellow liquid 4-formyl-N- (2-hydroxyethyl) -benzamide.
To 50 ml of concentrated sulfuric acid, 17 g (88 mmol) of 4-formyl-N- (2-hydroxyethyl) -benzamide was added dropwise with stirring, and the mixture was heated at 100 ° C. for 1 hour. To this solution, 500 ml each of 20% sodium hydroxide solution and chloroform were mixed and added dropwise with stirring, and the temperature was maintained at 15 ° C. or lower. The product layer was separated and dried to give 6.3 g (36 mmol) of 4- (2-oxazolyl) -benzaldehyde (41% yield).
A mixture of 6.3 g (1 equivalent) of 4- (2-oxazolyl) -benzaldehyde and 1.7 g (36 mmol) of N-methyl-hydroxyamine was refluxed in 100 ml of ethanol for 30 minutes and concentrated to a volume of 50 ml. The same amount of 50 ml of water was added and the mixture was cooled to 5 ° C. overnight in a refrigerator. White crystals were obtained by filtration and drying, yielding 5.1 g of 4- (2-oxazolyl) -phenyl-N-methylnitrone (69% yield).

Next, the processability of the rubber composition and the tire performance test were performed for each of the examples and comparative examples. The results are shown in Table 1. The processability was measured by Mooney viscosity, and the performance test was evaluated for exothermicity as follows.
<Measurement of Mooney viscosity>
Using MOMONYVISCOMETER SMV201 manufactured by SHIMAZU, the rubber composition sample was heated at 130 ° C. for 1 minute, the rotor was started, and the value after 4 minutes was measured as ML _{1 + 4} . Each example was indicated by an index with Comparative Example 2 as a control value (control) 100. The larger the index value, the lower the viscosity and the better the workability.
Index = (measured viscosity / control viscosity) × 100
<Evaluation of low heat generation>
A drum system with a speed and step load condition of 10 km / h was implemented, the temperature at a position at a constant depth of the tread was measured, and each example was displayed as an index with Comparative Example 6 as a control value (control) 100. It shows that it is excellent in low exothermic property, so that the value of an index | exponent is large.

  When the results of Examples 1 to 3 and Comparative Example 1 and Examples 5 to 6 and Comparative Example 2 were compared, both compounds were used compared to Comparative Example in which neither Compound D nor Compound M was used. Then, although workability is slightly lowered, low heat build-up is remarkably increased. Moreover, when Example 4-9 and Comparative Examples 3-6 are seen, workability | operativity will worsen, if only the compound D is used, By using together with the compound M, low exothermic property is excellent, and workability | operativity is also improved, It can be seen that when the hydrazide compound is added in Examples 10 to 11, the low exothermicity is improved.

  Since the rubber composition of the present invention and the pneumatic tire using the rubber composition are excellent in low heat buildup and wear resistance, they can be suitably used for heavy load tires and off-road tires, and have high industrial utility value.

Claims (11)

  A part Q containing dipolar nitrogen and a part containing 4-6 nitrogen-containing heterocycles containing oxygen or sulfur with respect to 100 parts by mass of at least one rubber component selected from the group consisting of natural rubber and synthetic rubber A rubber comprising 0.1 to 30 parts by mass of compound D having B and silica and 0.1 to 10 parts by mass of partial ester compound M of maleic acid and a (poly) oxypropylene derivative at the same time Composition.   The dipolar nitrogen portion Q of the compound D is selected from at least one of A1-C (A2) = N (A3) → O, A1-C≡N → O, and A1-C≡N → N-A4. A1 to A4 may be different from each other, hydrogen or a group having 20 or less carbon atoms or a linking chain connecting the B, and the compound is bonded to at least one of A1 to A4 and the B is connected. The rubber composition according to claim 1, which is a compound.   A1 to A4 of the compound D are hydrogen, an alkyl group having 1 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms (provided that the aromatic ring has a nitro group or a cyano group). A chloro group, a bromo group, an acyl group, a carbonylalkyl group, an alkyl group, and an alkoxyl group), or a connecting chain thereof. Rubber composition.   The rubber composition according to claim 1, wherein the nitrogen-containing heterocyclic ring at the B portion of the compound D is oxazoline or thiazoline.   Compound D is 4- (2-oxazolyl) -phenyl-N-methyl-nitrone, 4- (2-thiazolyl) -phenyl-N-methyl-nitrone, 4- (2-oxazolyl) -phenyl-N-phenyl. -Nitrone, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrone, phenyl-N-4- (2-oxazolyl) -phenyl-nitrone, phenyl-N-4- (2-thiazolyl) -phenyl-nitrone 4-tolyl-N-4- (2-oxazolyl) -phenyl-nitrone, 4-tolyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4-methoxyphenyl-N-4- (2-oxazolyl) ) -Phenyl-nitrone, 4-methoxyphenyl-N-4- (2-thiazolyl) -phenyl-nitrone, 4- (2-oxazolyl) -phenyl-nitrileoxy 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-methyl-nitrileimine, 4- (2-thiazolyl) -phenyl-nitrile oxide, 4- (2-oxazolyl) -phenyl-N-phenyl-nitrileimine, 4- (2-thiazolyl) -phenyl-N-phenyl-nitrileimine, phenyl-N-4 The rubber composition according to claim 4, wherein the rubber composition is one or more selected from-(2-oxazolyl) -phenyl-nitrileimine and phenyl-N-4- (2-thiazolyl) -phenyl-nitrileimine.   The rubber composition according to any one of claims 1 to 5, further comprising 0.1 to 5.0 parts by mass of a hydrazide compound Z in the rubber composition.   The rubber composition according to any one of claims 1 to 6, comprising 50 parts by mass or more of natural rubber in 100 parts by mass of the rubber component in the rubber composition.   The rubber composition according to any one of claims 1 to 7, wherein the silica content in the rubber composition is 2 to 50 parts by mass with respect to 100 parts by mass of the rubber component.   A pneumatic tire using the rubber composition according to any one of claims 1 to 8 as a tire member.   The pneumatic tire according to claim 9, wherein the pneumatic tire is a heavy duty pneumatic tire.   The pneumatic tire according to claim 10, wherein the heavy-duty pneumatic tire is an off-road tire.