JP2017110053A - Additive for rubber, rubber composition, and pneumatic tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for rubber capable of providing a rubber composition capable of achieving both low heat build-up properties and a high elastic modulus, a rubber composition containing the additive for rubber, and a pneumatic tire using the rubber composition.SOLUTION: The additive for rubber contains a benzimidazole compound represented by formula (I). The rubber composition contains the additive for rubber, and the pneumatic tire uses the rubber composition. [Q represents an amino group or a functional group represented by formula (Q) (Rand Rare each independently H, a 1-6C alkyl group, or a phenyl group which is unsubstituted or substituted with a halogen atom, a hydroxyl group, an amino group, a nitro group, a nitrile group, or a 1-6C alkyl group; and Rand Rmay be bonded to each other to form a 2-7C alkylene group).]SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a rubber additive, a rubber composition, and a pneumatic tire using the same, and more specifically, a rubber additive, a rubber composition, and a rubber composition that can achieve both low heat generation and high elastic modulus. It relates to the used pneumatic tire.

  In pneumatic tires, in order to reduce rolling resistance and save fuel, research has been conducted for many years to improve the low heat buildup of the rubber composition of pneumatic tires, that is, to reduce tan δ. . However, when a specific compound is blended with the rubber composition in order to improve low heat build-up, there is a problem that the viscosity of the rubber composition before vulcanization is increased and workability is impaired.

  In order to solve such a problem, for example, in Patent Document 1, in order to improve low workability without reducing wear resistance and fracture resistance, and to improve workability by suppressing increase in viscosity, It has been proposed to incorporate a specific compound having a hydrazide skeleton into the composition.

Japanese Patent Laid-Open No. 10-330549

  The rubber composition for a tread described in Patent Document 1 can improve low heat buildup and workability without lowering wear resistance and fracture resistance, but at the same time achieves high elastic modulus. There was still room for improvement.

  Accordingly, an object of the present invention is to provide a rubber additive capable of providing a rubber composition capable of satisfying both low heat buildup and high elastic modulus, a rubber composition containing the rubber additive, and use thereof. It is to provide a pneumatic tire.

  As a result of intensive studies to solve the above problems, the present inventors have formulated a predetermined amount of a compound having a specific nitrogen-containing skeleton together with a predetermined amount of filler as a rubber additive in the rubber composition. The inventors have found that the object can be achieved and have completed the present invention.

（式中、Ｑは、アミノ基又は下記の官能基（Ｑ^１）を示し、

前記官能基（Ｑ^１）において、Ｒ^１及びＲ^２は、同一又は異なって、水素原子、炭素数１〜６のアルキル基、フェニル基（但し、フェニル環上にはハロゲン原子、水酸基、アミノ基、ニトロ基、ニトリル基、炭素数１〜６のアルキル基を有していてもよい）を示し、互いに結合して炭素数２〜７のアルキレン基を形成してもよい。）
で表されるベンゾイミダゾール化合物を含有してなることを特徴とするものである。 That is, the rubber additive of the present invention has the following formula (I),

(In the formula, Q represents an amino group or the following functional group (Q ¹ ),

In the functional group (Q ¹ ), R ¹ and R ² are the same or different and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group (however, a halogen atom, a hydroxyl group, an amino group on the phenyl ring) , A nitro group, a nitrile group, or an alkyl group having 1 to 6 carbon atoms) may be bonded to each other to form an alkylene group having 2 to 7 carbon atoms. )
It contains the benzimidazole compound represented by these, It is characterized by the above-mentioned.

  The rubber composition of the present invention comprises 10 to 160 parts by mass of filler and 0.01 to 30 parts by mass of the rubber additive of the present invention with respect to 100 parts by mass of the diene rubber component. It is characterized by being blended.

  Furthermore, the pneumatic tire of the present invention is characterized by using the rubber composition of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber additive which can provide the rubber composition which can make low exothermic property and high elastic modulus compatible can be provided. Furthermore, according to the present invention, it is possible to provide a rubber composition capable of achieving both low heat buildup and high elastic modulus without deteriorating various performances of the tire, and a pneumatic tire using the rubber composition.

  The embodiment of the present invention will be specifically described below.

（式中、Ｑは、アミノ基又は下記の官能基（Ｑ^１）を示し、

前記官能基（Ｑ^１）において、Ｒ^１及びＲ^２は、同一又は異なって、水素原子、炭素数１〜６のアルキル基、フェニル基（但し、フェニル環上にはハロゲン原子、水酸基、アミノ基、ニトロ基、ニトリル基、炭素数１〜６のアルキル基を有していてもよい）を示し、互いに結合して炭素数２〜７のアルキレン基を形成してもよい。）
で表されるベンゾイミダゾール化合物を含有してなるものである。 The rubber additive of the present invention has the following formula (I),

(In the formula, Q represents an amino group or the following functional group (Q ¹ ),

In the functional group (Q ¹ ), R ¹ and R ² are the same or different and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group (however, a halogen atom, a hydroxyl group, an amino group on the phenyl ring) , A nitro group, a nitrile group, or an alkyl group having 1 to 6 carbon atoms) may be bonded to each other to form an alkylene group having 2 to 7 carbon atoms. )
It contains the benzimidazole compound represented by these.

  By adding a rubber additive containing a benzimidazole compound represented by the formula (I) to a diene rubber component, the resulting rubber composition has excellent low heat buildup and high elastic modulus. Both can be achieved.

  That is, since the rubber additive of the present invention can be used as a low-loss agent, in other words, the rubber additive of the present invention is added to a diene rubber component and represented by the above formula (I). And a low-loss agent comprising a benzimidazole compound.

  In the present specification, each group shown is as follows.

  Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, C1-C6 linear or branched alkyl groups, such as an isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, and isohexyl group, are mentioned.

  Examples of the alkylene group having 2 to 7 carbon atoms include linear or branched chain such as ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group and heptamethylene group. And an alkylene group having 2 to 7 carbon atoms.

  The phenyl group may be substituted with an appropriate substituent at any substitutable position. Examples of the substituent include a halogen atom, a hydroxyl group, an amino group, a nitro group, a nitrile group, and a carbon number of 1 to 6 alkyl groups and the like.

  The rubber additive of the present invention is preferably a rubber additive containing a benzimidazole compound in which Q is an amino group among the benzimidazole compounds represented by the formula (I).

In the rubber additive of the present invention, in the benzimidazole compound represented by the formula (I), Q is a functional group (Q ¹ ), and R ¹ and R ² of the functional group (Q ¹ ) are It is preferably the same or different and is an additive for rubber containing a compound having an alkyl group having 1 to 6 carbon atoms, wherein R ^{1 of the} functional group (Q ¹ ) is a methyl group and R ² is an isobutyl group. More preferably, it is an additive for rubber containing a certain compound.

In the rubber additive of the present invention, in the benzimidazole compound represented by the formula (I), Q is a functional group (Q ¹ ), and R ¹ and R ² of the functional group (Q ¹ ) are A rubber additive containing a compound which is bonded to each other to form an alkylene group having 2 to 7 carbon atoms is preferred, and R ¹ and R ^{2 of} the functional group (Q ¹ ) are bonded to each other to form hexa More preferred is a rubber additive containing a compound that forms a methylene group.

Rubber additives of the present invention, among the benzimidazole compound represented by the formula (I), Q is a functional group (Q ^1), R 1 or R ² functional groups (Q ¹⁾ is, A rubber additive comprising a compound which is a phenyl group, preferably a rubber additive comprising a compound wherein R ^{1 of} the functional group (Q ¹ ) is a hydrogen atom and R ² is a phenyl group It is more preferable that

  By adding or blending the rubber additive of the present invention to the diene rubber component, it is possible to provide a rubber composition having both excellent low heat buildup and high elastic modulus.

The preferred specific compounds of the present invention are listed below.

  The benzimidazole compound represented by the formula (I) can be produced, for example, by the method shown in the following reaction formula-1.

（反応式中、Ｒ^１及びＲ^２は前記に同じ。） Reaction Formula-1

(In the reaction formula, R ¹ and R ² are the same as above.)

  According to Reaction Formula-1, the benzimidazole represented by the formula (Ib) is reacted with the benzimidazole compound represented by the formula (Ia) by reacting the carbonyl compound represented by the formula (1). Compounds can be produced.

  Although this reaction can be carried out in a solvent, a wide variety of known solvents can be used as the solvent to be used as long as they are inert to the reaction. Examples of such a solvent include ethers such as dimethyl ether, diethyl ether, diisopropyl ether, tert-butyl methyl ether, tetrahydrofuran, dioxane, tetrahydropyran, and 1,2-dimethoxyethane, and halogens such as dichloromethane, chloroform, and carbon tetrachloride. , Hydrocarbons such as hexane and cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene and styrene, alcohols such as methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol and tert-butanol, acetonitrile, Nitriles such as propionitrile, amides such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfora Sulfoxides etc. can be mentioned. These solvents can be used alone or in combination of two or more as required.

  These solvents may be used usually in an amount of about 1 to 100 parts by mass, preferably about 1 to 20 parts by mass with respect to 1 part by mass of the benzimidazole compound represented by the formula (Ia).

  The carbonyl compound of the formula (1) used in this reaction is an aldehyde compound or a ketone compound appropriately selected for producing the target benzimidazole compound represented by the formula (Ib).

  The carbonyl compound of the formula (1) is usually used in an amount of 1.0 to 20 equivalents, preferably 1.0 to 2.0 equivalents, relative to the benzimidazole compound represented by the formula (Ia). do it.

  This reaction can be carried out within a range from 0 ° C. to the boiling point of the solvent used, but is usually carried out at about 25 to 100 ° C., and may be adjusted in consideration of the solvent used, the reaction reagent, and the like.

  The reaction time varies depending on the reaction temperature and cannot be generally specified, but the reaction is usually completed in about 0.5 to 24 hours.

  The benzimidazole compound represented by the formula (Ia) can be produced by a conventionally known method, for example, a method described in US Publication US2007 / 0066670.

  The addition amount when the rubber additive of the present invention is added to the diene rubber component is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the diene rubber component. It is more preferable that it is 10 mass parts.

  The addition of the rubber additive of the present invention to the diene rubber component is preferably performed by a mixer, an extruder, a kneader or spraying.

  In the present specification, the expression “contains” includes the concepts “includes”, “consists essentially of”, and “consists only of”.

  The rubber composition of the present invention comprises 10 to 160 parts by mass of filler and 0.01 to 30 parts by mass of the rubber additive of the present invention with respect to 100 parts by mass of the diene rubber component. Become.

  Thereby, in the rubber composition, the chemical interaction between the filler and the rubber component is improved, and the reinforcing effect of the filler is improved. In particular, it is possible to further improve the reinforcing effect with respect to carbon black as a filler. As a result, hysteresis loss due to friction between the fillers is reduced, resulting in a low tan δ.

Next, the filler blended in the rubber composition of the present invention will be described.
In the rubber composition of the present invention, the filler is blended in an amount of 10 to 160 parts by mass, preferably 30 to 100 parts by mass with respect to 100 parts by mass of the diene rubber component. As the filler, carbon black is preferable, but carbon black and an inorganic filler may be used in combination. When used in combination with an inorganic filler, the inorganic filler is preferably used in an amount of 80 parts by mass or less with respect to 100 parts by mass of the diene rubber component. If carbon black is blended alone, a stronger reinforcing effect of carbon black can be obtained.

Carbon black as a filler used in the rubber composition of the present invention is not particularly limited. For example, high, medium or low structure SAF, ISAF, IISAF, N339, HAF, FEF, GPF, SRF grade carbon black In particular, it is preferable to use SAF, ISAF, IISAF, N339, HAF, and FEF grade carbon black. The nitrogen adsorption specific surface area (N ₂ SA, measured according to JIS K 6217-2: 2001) is preferably 30 to 250 m ² / g. This carbon black may be used individually by 1 type, and may be used in combination of 2 or more type.

  Silica is preferable as the inorganic filler other than carbon black used in the rubber composition of the present invention. Any commercially available silica can be used. Among these, wet silica, dry silica, and colloidal silica are preferably used, and wet silica is particularly preferably used.

  In the case where an inorganic filler such as silica is blended in the rubber composition of the present invention, it is preferable to blend a silane coupling agent from the viewpoint of enhancing the reinforcing effect of the inorganic filler, which further improves workability during rubber processing. It is possible to provide a pneumatic tire that is excellent and has better wear resistance. The silane coupling agent used in the rubber composition of the present invention is not particularly limited, and generally used silane coupling agents can be used.

  The rubber component used in the rubber composition of the present invention is required to be composed of 50% by mass or more of diene rubber, and is preferably 100% by mass of diene rubber. The diene rubber is preferably at least one selected from natural rubber and synthetic diene rubber. The synthetic diene rubber is not particularly limited as long as it is a rubber containing a diene monomer as at least a part of monomers constituting the rubber. Specifically, styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber {chlorine Butyl rubber (CI-IIR), brominated butyl rubber (Br-IIR), etc.}, ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-butadiene copolymer rubber (EBR), propylene-butadiene copolymer A combined rubber (PBR) or the like can be used, and natural rubber and synthetic diene rubber may be used singly or as a blend of two or more. Examples of rubber components other than diene rubber include ethylene-propylene copolymer rubber (EPM), acrylic rubber (ACM), chlorinated polyethylene (CM), epichlorohydrin rubber (CO, ECO), chlorosulfonated polyethylene (CSM), etc. Is mentioned.

  The rubber composition of the present invention contains, as other optional components, compounding agents usually used in the rubber industry, such as softeners, anti-aging agents, vulcanization accelerators, vulcanization accelerators, vulcanizers, and the like. They can be appropriately selected and blended within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition of the present invention can be produced by blending various compounding agents, kneading with a Banbury mixer, roll, intensive mixer, twin screw extruder, etc., heating, extruding and the like.

  The pneumatic tire of the present invention is formed by using the rubber composition of the present invention, and the rubber composition of the present invention is made of at least a tread portion, a sidewall portion, a bead portion, an inner liner, and other reinforcing rubber portions. It can be suitably used for one member. The pneumatic tire of the present invention is not particularly limited except that the above rubber composition is used, and can be manufactured according to a conventional method. Further, as the gas filled in the pneumatic tire, an inert gas such as nitrogen, argon, helium, or the like can be used in addition to normal or air whose oxygen partial pressure is adjusted.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Production Example 1 Production of (1H-benzoimidazol-2-yl) hydrazine (Compound a) 225 mL of water, 18 g of sodium hydroxide and 0.9 g of tungstic acid were added to 45 g of 2-mercaptobenzimidazole, and then cooled to 5 ° C. . After adding 102 g of 35% hydrogen peroxide dropwise and stirring at room temperature for 1 hour, 45 g of hydrazine hydrate was added and stirred at 90 ° C. for 13 hours. The precipitated solid was collected by filtration, dispersed and washed with 100 mL of water, and then dried under reduced pressure to obtain 40.9 g (yield 92%) of the desired (1H-benzoimidazol-2-yl) hydrazine (compound a).
Property: Pale yellow solid Melting point: 218 ° C
¹ H-NMR (500 MHz, DMSO-D ₆ , δ ppm): 4.4 (br-s, 2H), 6.9 (m, 2H), 7.1 (m, 2H), 7.8 (br— s, 1H), 11.0 (br-s, 1H)

Production Example 2 Production of N- (1H-benzimidazol-2-yl) -N ′-(4-methylpentan-2-ylidene) hydrazine (Compound b) (1H-Benzimidazol-2-yl produced in Production Example 1 Yl) 50 mL of methyl isobutyl ketone was added to 6 g of hydrazine and stirred at 60 ° C. for 6 hours. After evaporating the reaction solvent under reduced pressure, the desired product was collected by silica gel column chromatography (ethyl acetate), dried under reduced pressure, and the desired N- (1H-benzimidazol-2-yl) -N ′-(4-methyl). 8.6 g (yield 92%) of pentane-2-ylidene) hydrazine (compound b) was obtained.
Properties: Light yellow solid Melting point: 70 ° C
¹ H-NMR (500 MHz, DMSO-D ₆ , δ ppm): 0.9 (m, 6H), 1.9 to 2.3 (m, 6H), 6.9 (m, 2H), 7.2 ( m, 2H), 10.1 (br-s, 1H), 11.1 (br-s, 1H)

Production Example 3 Production of N- (1H-benzimidazol-2-yl) -N ′-(cyclohexane-1-ylidene) hydrazine (Compound c) (1H-Benzimidazol-2-yl) hydrazine produced in Production Example 1 Methanol 100mL and cyclohexanone 16g were added to 6g, and it stirred at 60 degreeC for 6 hours. The precipitated crystals were collected by filtration, dispersed and washed with 40 mL of isopropyl alcohol, and dried under reduced pressure to obtain the target N- (1H-benzoimidazol-2-yl) -N ′-(cyclohexane-1-ylidene) hydrazine (compound c). ) 6.0 g (yield 65%) was obtained.
Property: Pale yellow solid Melting point: 235 ° C
¹ H-NMR (500 MHz, DMSO-D ₆ , δ ppm): 1.6 (m, 4H), 1.7 (m, 2H), 2.3 (t, 2H), 2.5 (m, 2H) , 6.9 (m, 2H), 7.2 (m, 2H), 10.2 (br-s, 1H), 11.2 (br-s, 1H)

Production Example 4 N- (1H-Benzimidazol-2-yl) -N ′-(2-hydroxybenzylidene) hydrazine (Compound d)
After adding 80 mL of methanol and 13.2 g of salicylaldehyde to 4 g of (1H-benzoimidazol-2-yl) hydrazine prepared in Production Example 1, the mixture was stirred at 50 ° C. for 30 minutes. The precipitated solid was collected by filtration, dispersed and washed with 30 mL of methanol, and dried under reduced pressure to obtain the desired N- (1H-benzoimidazol-2-yl) -N ′-(2-hydroxybenzylidene) hydrazine (Compound d). 6.3 g (yield 93%) was obtained.
Property: Pale yellow solid Melting point: 268 ° C
¹ H-NMR (500 MHz, DMSO-D ₆ , δ ppm): 6.9 (m, 2H), 7.0 (m, 2H), 7.2 (m, 3H), 7.8 (d, 1H) , 8.3 (s, 1H), 10.3 (br-s, 1H), 11.3 (br-s, 1H), 11.5 (br-s, 1H)

(Examples 1-4, Comparative Examples 1-2)
Various test rubber compositions were prepared according to the formulation shown in Table 1 below. The resulting rubber composition was measured for dynamic elastic modulus E ′ and tan δ. The measuring method is as follows.

(Dynamic elastic modulus E ′ and tan δ)
Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Ueshima Seisakusho, measured at a frequency of 52 Hz, an initial strain of 10%, a measurement temperature of 60 ° C., and a dynamic strain of 1%, the obtained dynamic elastic modulus E ′ or tan δ The numerical values are indicated by indices according to the following formula, with the numerical value of the dynamic elastic modulus E ′ or tan δ of Comparative Example 1 being 100. In the dynamic elastic modulus E ′, the larger the exponent value, the higher the dynamic elastic modulus E ′. On the other hand, in the tan δ index, the smaller the index value, the lower the heat generation and the smaller the hysteresis loss.

Dynamic elastic modulus E ′ index = {(Dynamic elastic modulus E ′ of test vulcanized rubber composition) / (Dynamic elastic modulus E ′ of vulcanized rubber composition of Comparative Example 1)} × 100

tan δ index = {(tan δ of test vulcanized rubber composition) / (tan δ of vulcanized rubber composition of Comparative Example 1)} × 100

＊４ Ｎ，Ｎ’−ジ−（１Ｈ−ベンゾイミダゾール−２−イル）−２，２’−ジスルファンジイルエタンアミン

＊５ 富士興産（株）製「アロマックス＃３」
＊６ 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、大内新興化学工業株式会社製、商品名「ノクラック６Ｃ」
＊７ ２,２,４−トリメチル−１,２−ジヒドロキノリン重合体、大内新興化学工業株式会社製、商品名「ノクラック２２４」
＊８ Ｎ−シクロヘキシル−２−ベンゾチアゾールスルフェンアミド、三新化学工業（株）製「サンセラーＣＭ」 * 1 RSS # 1
* 2 “# 80” manufactured by Asahi Carbon Co., Ltd.
* 3 3-hydroxy-N '-(1,3-dimethylbutylidene) -2-naphthoic acid hydrazide

* 4 N, N′-di- (1H-benzimidazol-2-yl) -2,2′-disulfanediylethanamine

* 5 “Aromax # 3” manufactured by Fuji Kosan Co., Ltd.
* 6 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd., trade name “NOCRACK 6C”
* 7 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 8 N-cyclohexyl-2-benzothiazolesulfenamide, "Sunseller CM" manufactured by Sanshin Chemical Industry Co., Ltd.

  As is clear from Table 1, the rubber compositions of Examples 1 to 4 in which the rubber additive of the present invention was blended were both elastic modulus and low heat generation as compared with the rubber compositions of Comparative Examples 1 and 2. It was good in both sex.

Claims (9)

The following formula (I),

(In the formula, Q represents an amino group or the following functional group (Q ¹ ),

In the functional group (Q ¹ ), R ¹ and R ² are the same or different and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group (however, a halogen atom, a hydroxyl group, an amino group on the phenyl ring) , A nitro group, a nitrile group, or an alkyl group having 1 to 6 carbon atoms) may be bonded to each other to form an alkylene group having 2 to 7 carbon atoms. )
A rubber additive comprising a benzimidazole compound represented by the formula:   The rubber additive according to claim 1, which is used as a low-loss agent.   The rubber additive according to claim 1 or 2, wherein in the benzimidazole compound represented by the formula (I), Q is an amino group. The rubber additive according to claim 1 or 2, wherein in the benzimidazole compound represented by the formula (I), Q is a compound having a functional group (Q ¹ ).   Compounding 10 to 160 parts by mass of filler and 0.01 to 30 parts by mass of the rubber additive according to any one of claims 1 to 4 with respect to 100 parts by mass of the diene rubber component. A rubber composition characterized by comprising:   The rubber composition according to claim 5, wherein the diene rubber component contains natural rubber.   The rubber composition according to claim 5, wherein the filler contains carbon black.   A pneumatic tire using the rubber composition according to any one of claims 5 to 7.   The pneumatic tire according to claim 8, wherein the rubber composition is used for at least one member of a tread portion, a sidewall portion, a bead portion, an inner liner, and other reinforcing rubber portions.