JP2011074155A - Tire rubber composition and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire rubber composition which can simultaneously achieve grip performance and blow performance and a pneumatic tire using the same. <P>SOLUTION: The tire rubber composition includes an acid, a nitrogen compound, and an alkylphenol-sulfur chloride condensate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a rubber composition for tires and a pneumatic tire using the same.

Conventionally, a method of blending a nitrogen compound and an acid to generate hysteresis loss and improving grip performance has been used particularly for tread rubber of a racing tire (for example, Patent Document 1). However, although the grip performance can be improved by blending the nitrogen compound and the acid, there is a problem that the blow performance is deteriorated.

JP 2008-163108 A

An object of the present invention is to solve the above-mentioned problems and provide a rubber composition for a tire that can achieve both grip performance and blow performance, and a pneumatic tire using the same.

The present invention relates to a tire rubber composition containing an acid, a nitrogen compound, and an alkylphenol / sulfur chloride condensate.

The acid is preferably a carboxylic acid or a phenol derivative.

The nitrogen compound is preferably an imidazole.

The tire rubber composition is preferably used for a tread.

The present invention also relates to a pneumatic tire using the rubber composition. The pneumatic tire is preferably a competition tire.

According to the present invention, since it is a rubber composition for a tire containing an acid, a nitrogen compound, and an alkylphenol / sulfur chloride condensate, the blow performance can be improved while improving the grip performance, and the grip performance It is possible to provide a pneumatic tire that balances blow performance.
Blowing refers to damage such as tire surface rubber boils, becomes blisters, and rubber scatters. Such damage can be suppressed as the blow performance is higher. By blending the alkylphenol / sulfur chloride condensate, it is possible to suppress the decrease in scorch time.

The tire rubber composition of the present invention includes an acid, a nitrogen compound, and an alkylphenol / sulfur chloride condensate.

The rubber components that can be used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber ( IIR) and diene rubbers such as styrene-isoprene-butadiene copolymer rubber (SIBR) may be used. These diene rubbers may be used alone or in combination of two or more. Among these, SBR is preferable because grip performance as a racing tire can be obtained.

The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR) and the like can be used.

The styrene content of SBR is preferably 10% by mass or more, more preferably 25% by mass or more, and still more preferably 35% by mass or more. If it is less than 10% by mass, tan δ is low, and high grip performance may not be obtained. The styrene content is preferably 50% by mass or less, more preferably 45% by mass or less. If it exceeds 50% by mass, the rubber hardness at room temperature is too high, and grip performance may not be exhibited.

When the rubber composition of the present invention contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass. If it is less than 80% by mass, sufficient tan δ cannot be obtained, and satisfactory grip performance may not be obtained.

In the present invention, an acid is used. It does not specifically limit as an acid, For example, carboxylic acid, a phenol derivative, a sulfonic acid etc. are mentioned. Of these, carboxylic acids and phenol derivatives are preferred because they have a high effect of improving grip performance.

Carboxylic acids include aliphatic monocarboxylic acids such as acetic acid, propionic acid and oleic acid, aliphatic dicarboxylic acids such as succinic acid and maleic acid, benzoic acid, benzoic acid derivatives, aromatic monocarboxylic acids such as cinnamic acid and naphthoic acid. Aromatic polycarboxylic acids such as carboxylic acid, phthalic acid, phthalic anhydride, trimellitic acid and pyromellitic acid can be mentioned. Of these, aromatic monocarboxylic acids are preferable, and benzoic acid and benzoic acid derivatives are more preferable. Examples of the benzoic acid derivative include those in which a functional group such as a hydrocarbon group (alkyl group, alkoxy group, etc.) or a hydroxyl group is introduced into benzoic acid. Specifically, p-methylbenzoic acid, p- Examples include methoxybenzoic acid, p-chlorobenzoic acid, p-nitrobenzoic acid, and salicylic acid.

Examples of the phenol derivative include compounds represented by the following general formulas (I) to (IV).

In the general formulas (I) to (IV), R ^{1 to} R ⁷ are the same or different and are each a hydrocarbon group having 1 to 10 (preferably 1 to 6) carbon atoms. As this hydrocarbon group, a C1-C10 (preferably 1-6) alkyl group and a C1-C10 (preferably 1-6) alkenyl group are preferable, for example, a methyl group, an ethyl group, n -Propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, i-pentyl group, n-hexyl group, i-hexyl group and the like can be mentioned.

n and n ′ are the same or different and are 0 or an integer of 1 to 3. n and n ′ are preferably 1 to 2.
m and m ′ are the same or different and are integers of 1 or 2. m and m ′ are preferably 1.
s is an integer of 1 to 3. It is preferable that s is 1-2.
t is 0 or an integer of 1 to 3. t is preferably 1 to 2.

X is an atom selected from the group consisting of an oxygen atom, a sulfur atom and a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms which may contain the atom. Examples of the hydrocarbon group include an alkylene group, a cycloalkylene group, and an unsaturated group thereof. For example, a methylene group, an ethylene group, a propylene group, an n-butylene group, an i-butylene group, a pentylene group, a hexylene group, a heptylene group, etc., and an unsaturated group such as a vinylene group, a propylidene group, an isopropylidene group, or a butylidene group , Isobutylidene groups, ester bond-containing groups, aromatic groups and the like. Preferred specific examples of X are the following (1) to (3). The ester bond-containing group is a group containing —CO—O—, and specific examples include those represented by the following (4) to (7).

Specific examples of the phenol derivatives represented by the general formulas (I) to (IV) include, for example, 2-tert-butylphenol; 2-ethyl-6-methylphenol; 2,6-di-tert-butylphenol; 3 -Methyl-2,6-bis (1-methylethyl) phenol; 4-methyl-2,6-di-tert-butylphenol; 3-methyl-2,6-bis (1-methylpropyl) phenol; 2-butyl -6-ethylphenol; 4-butyl-2,6-di-tert-butylphenol; 4-tert-butyl-2,6-dimethylphenol; 6-tert-butyl-2,3-dimethylphenol; 2-tert- Butyl-4-methylphenol; 2-cyclohexyl-6-tert-butylphenol; 2-cyclohexyl-6-tert-butyl-4-methyl 2-tert-butyl-4,6-dimethylphenol; 4,4'-dihydroxybiphenyl; 4,4'-thiobisphenol; hydroquinone; 1,5-hydroxynaphthalene; 4,4'-thiobis (3- 4,4'-thiobis (2-methyl-6-tert-butylphenol); 4,4'-methylenebis (2,6-di-tert-butylphenol); 4,4'- Ethylene bis (2,6-di-tert-butylphenol); 4,4′-propylidenebis (2-methyl-6-tert-butylphenol); 4,4′-bis (2,6-di-tert-butylphenol); 4,4'-bis (2-methyl-6-tert-butylphenol); 2,2'-methylenebis (4-ethyl-6-tert- Tilphenol); 2,2′-methylenebis (4-methyl-6-tert-butylphenol); 4,4′-butylidenebis (3-methyl-6-tert-butylphenol); 4,4′-isopropylidenebis (2 , 6-di-tert-butylphenol); 2,2′-methylenebis (4-methyl-6-nonylphenol); 2,2′-isobutylidenebis (4,6-dimethylphenol); 2,2′-methylenebis (4-methyl-6-cyclohexylphenol) and the like. Among them, 2,2′-methylenebis (4-methyl-6-tert-butylphenol) and 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) are preferable because of the high effect of improving the grip performance. preferable.

The said acid may be used independently and may be used in combination of 2 or more type.

The content of the acid is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, a sufficient improvement in grip performance may not be obtained. The acid content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. When the amount exceeds 10 parts by mass, there is a tendency that the effect of improving the grip performance commensurate with the blending amount cannot be obtained, and the wear resistance tends to deteriorate.

In the present invention, a nitrogen compound is used. The nitrogen compound is preferably one capable of forming a hydrogen bond, and by blending such a nitrogen compound in the rubber composition, grip performance under an intermediate temperature condition (30 to 50 ° C.) can be improved.

The nitrogen compound preferably has one or more cyclic structures containing nitrogen. If no annular structure containing nitrogen is included, the high temperature grip performance tends not to be improved.

Examples of such nitrogen compounds include piperidine derivatives, imidazoles, caprolactams, and the like. Among these, imidazoles are preferable because they are general-purpose products and easily available.

When imidazoles are used as the nitrogen compound, it is preferable to use imidazoles represented by the following general formula (V).

Wherein R ⁸ is the same or different and is a monovalent linear hydrocarbon group, phenyl group, —OH, —CN, —NH ₂ or —SH. Y is an integer of 0 to 4. And the total number of carbon atoms of y R ⁸ is 10 or less.)

Among them, R ⁸ is more preferably a monovalent linear hydrocarbon group, an alkyl group is more preferable, and a methyl group is particularly preferable, because there is little steric hindrance and reaction with an acid is likely to occur effectively. preferable.

The number y of the substituents R ⁸ preferably is an integer of 0 to 4, for the reason that can be a steric hindrance and a large number of substituents R ^8, more preferably 1-2, 1 being more preferred.

Further, the total number of carbon atoms of y R ⁸ is preferably 10 or less, more preferably 7 or less, and still more preferably 5 or less. When the total carbon number of R ⁸ is 11 or more, the steric hindrance is large, hydrogen bonds cannot be formed effectively, and a sufficient improvement effect of grip performance tends not to be obtained.

Specific examples of the imidazoles represented by the general formula (V) include, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 1-propylimidazole, and 2-propyl. Imidazole, 1-cyanoimidazole, 2-cyanoimidazole, 1,2-dimethylimidazole, 1,2-diethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-ethylimidazole, 1-methyl-2- Examples include benzylimidazole and 1-ethyl-2-benzylimidazole. Of these, 2-methylimidazole, 2-cyanoimidazole, 1,2-dimethylimidazole, and 1-benzyl-2-methylimidazole are preferable because the effect of improving grip performance is high.

Nitrogen compounds may be used singly or in combination of two or more, but combining two or more may be less effective and may be used alone as a result of reduced rubber strength. preferable.

The content of the nitrogen compound is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, a sufficient improvement in grip performance may not be obtained. The content of the nitrogen compound is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. When the amount exceeds 10 parts by mass, the effect of improving the grip performance commensurate with the blending amount tends not to be obtained, and the wear resistance tends to deteriorate.

In the present invention, an alkylphenol / sulfur chloride condensate is used. By blending the alkylphenol / sulfur chloride condensate, the blow performance can be improved while suppressing a decrease in grip performance. Moreover, although there exists a concern about the fall of a scorch time by mix | blending an acid and a nitrogen compound, the fall of a scorch time can be suppressed by further mix | blending an alkylphenol and sulfur chloride condensate. Therefore, the problem of rubber burn hardly occurs in the finish kneading or the extrusion process. Examples of the alkylphenol / sulfur chloride condensate include those represented by the following formula.

（式中、ｇは０又は１〜１０の整数であり、ｆは２〜４の整数であり、Ｒは炭素数５〜１２のアルキル基である。）

(In the formula, g is 0 or an integer of 1 to 10, f is an integer of 2 to 4, and R is an alkyl group having 5 to 12 carbon atoms.)

From the viewpoint of good dispersibility of the alkylphenol / sulfur chloride condensate in rubber, g is preferably an integer of 1 to 9. Further, f is preferably an integer of 2 to 4 and more preferably 2 from the viewpoint of efficiently improving the blow performance. When f exceeds 4, it tends to become thermally unstable, and when f is 1, the sulfur content (weight of sulfur) in the alkylphenol-sulfur chloride condensate decreases. From the viewpoint of good dispersibility in rubber, the lower limit of R is preferably an alkyl group having 5 or more carbon atoms, more preferably 6 or more, and the upper limit is preferably 12 or less carbon atoms, more preferably 9 or less carbon atoms. It is an alkyl group. Specific examples of the alkylphenol / sulfur chloride condensate include Tackrol V200 (Taoka Chemical Co., Ltd.) having an alkyl group having g of 0 to 10, f of 2, R of C ₈ H ₁₇ and a sulfur content of 24% by mass. Manufactured). The alkylphenol / sulfur chloride condensate may be used alone or in combination of two or more.

The content of the alkylphenol / sulfur chloride condensate is preferably 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, a sufficient improvement in blow performance may not be obtained. The content of the alkylphenol / sulfur chloride condensate is preferably 10 parts by mass or less, more preferably 8 parts by mass or less. When it exceeds 10 parts by mass, grip performance tends to deteriorate.

The rubber composition of the present invention preferably contains a tackifier resin. The tackifying resin is generally a thermoplastic resin having a molecular weight of several hundred to several thousand, which means a resin that imparts tackiness by blending with natural rubber or synthetic rubber, and uses various natural resins and synthetic resins. be able to. Specifically, natural resins such as rosin resins and terpene resins, synthetic resins such as petroleum resins, phenol resins, coal resins, and xylene resins can be used. The tackifying resins may be used alone or in combination of two or more. Of these, petroleum resins are preferred because they have a high effect of improving grip performance.

Petroleum resin is a mixture of cracked oil fractions containing unsaturated hydrocarbons such as olefins and diolefins by-produced together with petrochemical basic raw materials such as ethylene and propylene by thermal decomposition of naphtha in the petrochemical industry. It is obtained by polymerization with a Friedel-Crafts type catalyst. The petroleum-based resin, C ₅ fraction (co) polymer obtained by aliphatic petroleum resin, a C ₉ fraction obtained by thermal cracking of naphtha (co) polymerization obtained by thermal cracking of naphtha aromatic petroleum resin obtained Te, the C ₅ fraction and C ₉ fraction copolymerized copolymerization petroleum resin obtained, hydrogenation system, dicyclopentadiene-based such as alicyclic compound-based petroleum resins, Examples thereof include petroleum resins such as styrene resins such as styrene, substituted styrene, and copolymers of styrene and other monomers. The _{C 5} fraction obtained by thermal cracking of naphtha, usually 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-olefin such as butene Examples include hydrocarbons, diolefin hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, 3-methyl-1,2-butadiene, and the like. Also, the C ₉ fraction (co) polymerized aromatic petroleum resin obtained, a vinyl toluene, a resin obtained by polymerizing an aromatic carbon atoms 9, indene major monomer, the thermal decomposition of naphtha specific examples of the C ₉ fraction obtained by, alpha-methyl styrene, beta-methyl styrene, .gamma.-methyl styrene homologs and indene such as styrene, indene analogs such as coumarone and the like. Product names include Petrogin manufactured by Mitsui Petrochemical Co., Ltd., Petlite manufactured by Mikuni Chemical Co., Ltd., Neopolymer manufactured by Nippon Petrochemical Co., Ltd., Petcoal manufactured by Toyo Soda Co., Ltd.

In the present invention, because of high effect of improving grip performance, modified petroleum resin modified petroleum resin comprising the C ₉ fraction, it is preferably used. The modified petroleum resins, include C ₉ petroleum resins modified with an unsaturated alicyclic compound, C ₉ petroleum resins modified with a compound having a hydroxyl group, C ₉ petroleum resins modified with unsaturated carboxylic acid compounds and the like It is done.

The softening point of the tackifying resin is preferably 60 ° C. or higher, and more preferably 80 ° C. or higher. When the softening point of the tackifying resin is less than 60 ° C., the grip performance under a high temperature condition tends to be lowered. Further, the softening point of the tackifying resin is preferably 180 ° C. or less, and more preferably 150 ° C. or less. When the softening point of the tackifying resin exceeds 180 ° C., the dispersibility during kneading tends to decrease.
The softening point of the tackifying resin is a value measured by the ring and ball method (JIS K2207).

The content of the tackifying resin is preferably 1 part by mass or more, and more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 1 part by mass, a sufficient improvement in grip performance may not be obtained. The content of the tackifying resin is preferably 15 parts by mass or less, more preferably 10 parts by mass or less. If it exceeds 15 parts by mass, the hardness may be too high and sufficient grip performance may not be obtained.

In addition to the above-mentioned components, the rubber composition of the present invention includes compounding agents generally used in the production of rubber compositions, such as reinforcing fillers such as carbon black and silica, silane coupling agents, zinc oxide, stearin. Acids, various antioxidants, oils, waxes, vulcanizing agents, vulcanization accelerators, and the like can be appropriately blended.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing. The rubber composition can be used for each member of a tire, and can be preferably used for a tread.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of each tire member such as a tread at an unvulcanized stage, and is molded together with the other tire members by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The pneumatic tire of the present invention is preferably used as a tire for passenger cars, a tire for trucks and buses, a tire for motorcycles, a tire for competition, and the like, and particularly preferably used as a tire for competition. The pneumatic tire obtained by the present invention can achieve both grip performance and blow performance.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
SBR: Toughden 4350 manufactured by Asahi Kasei Corporation (styrene content: 39% by mass, containing 50 parts by mass of oil with respect to 100 parts by mass of rubber solid content)
Carbon black: Diamond Black A (N110) manufactured by Mitsubishi Chemical Corporation
Anti-aging agent 6C: Santoflex 13 from Flexis
Anti-aging agent 224: NOCRACK 224 manufactured by Flexis
Stearic acid: Zinc stearate oxide manufactured by NOF Corporation: Zinc oxide type 2 aroma oil manufactured by Mitsui Kinzoku Kogyo Co., Ltd. Process X-260 manufactured by Japan Energy
Tackifying resin 1: Neopolymer 140 manufactured by Nippon Petrochemical Co., Ltd. (softening point: 145 ° C., acid value: 0 mgKOH / g, aromatic petroleum resin)
Tackifying resin 2: Escron V120 manufactured by Nippon Steel Chemical Co., Ltd. (softening point: 120 ° C., acid value: 0.30 mg KOH / g, modified coumarone resin (modified petroleum resin))
Nitrogen compound 1: 2MZ (2-methylimidazole) manufactured by Shikoku Kasei Co., Ltd.
Nitrogen compound 2: 2CNZ (2-cyanoimidazole) manufactured by Shikoku Kasei Co., Ltd.
Acid 1: NOCRACK NS-30 (4,4'-butylidenebis (3-methyl-6-tert-butylphenol)) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Acid 2: Nocrack NS-6 (2,2′-methylenebis (4-methyl-6-tert-butylphenol)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Noxeller NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Cross-linking agent: Tacchiol V200 (alkylphenol / sulfur chloride condensate) manufactured by Taoka Chemical Co., Ltd.

Examples 1-9 and Comparative Examples 1-3
According to the blending contents shown in Table 1, using a BP Banbury mixer, materials other than sulfur, vulcanization accelerator, and crosslinking agent are kneaded for 3 minutes at 150 ° C. to obtain a kneaded product. It was. Next, sulfur, a vulcanization accelerator, and a crosslinking agent were added to the kneaded material obtained, and kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 12 minutes to obtain a vulcanized rubber sheet.
Further, the obtained unvulcanized rubber composition is formed into a tread shape, bonded to another tire member, formed into a tire, and vulcanized at 170 ° C. for 12 minutes to test cart tires (tire size: 11). X 7.10-5) was produced.

The following evaluation was performed using the obtained vulcanized rubber sheet and test cart tire. Each test result is shown in Table 1.

(Grip performance)
The test cart tire was attached to the test cart, and the test course of 1 lap 2 km was run 8 laps. The grip performance of the tire of Comparative Example 1 was set to 3 points, and the test driver made a sensory evaluation with a maximum score of 5 points. The larger the value, the better the grip performance.

(Blow performance)
The vulcanized rubber sheet was placed in an oven, the oven temperature was gradually raised (temperature increase rate: 1 ° C./min), the vulcanized rubber sheet was observed, and the temperature at which blow occurred was measured. The results were expressed as an index, with Comparative Example 1 taken as 100. A larger index indicates that blow did not occur up to a higher temperature, and the blow performance is better.

(Scorch time)
A test was performed in accordance with the Mooney scorch test of the unvulcanized rubber physical test method of JIS K6300, and t10 (min) at 130.0 ± 0.5 ° C. was measured. It showed in. A larger index indicates that it is possible to suppress early vulcanization and is preferable. Conversely, the smaller the index, the shorter the scorch time, and there is a tendency for rubber scorching problems to occur in the finish kneading and extrusion processes.

In an example containing an acid, a nitrogen compound, and an alkylphenol / sulfur chloride condensate, the blowing performance could be improved while the grip performance was improved. Furthermore, in Examples 6-8 which mix | blended tackifying resin, the grip performance was able to be improved more. On the other hand, in Comparative Example 1 containing neither an acid, a nitrogen compound, nor an alkylphenol / sulfur chloride condensate, the grip performance and the blow performance were not compatible. Comparative Example 2 containing an acid and a nitrogen compound and no alkylphenol / sulfur chloride condensate was greatly inferior in blowing performance. Comparative Example 3 containing no acid or nitrogen compound and containing an alkylphenol-sulfur chloride condensate was greatly inferior in grip performance. Moreover, it was found that the examples had a larger scorch time index than the comparative examples and were able to suppress early vulcanization.

Claims (6)

A tire rubber composition comprising an acid, a nitrogen compound, and an alkylphenol-sulfur chloride condensate. The tire rubber composition according to claim 1, wherein the acid is a carboxylic acid or a phenol derivative. The rubber composition for tires according to claim 1 or 2, wherein the nitrogen compound is an imidazole. The rubber composition for a tire according to any one of claims 1 to 3, which is used for a tread. A pneumatic tire using the rubber composition according to claim 1. The pneumatic tire according to claim 5, which is a racing tire.