JP7400419B2 - Rubber compositions and pneumatic tires - Google Patents

Description

The present invention relates to a rubber composition and a pneumatic tire.

Rubber compositions for tires include those containing diene rubber, fillers, etc., and various materials are used to improve tire performance such as handling stability during driving, wear resistance, and fuel efficiency. (See Patent Document 1).

Such diene rubbers usually form rubber compositions through irreversible bonds such as covalent bonds with other materials, and breakage occurs due to deterioration.

International Publication No. 2013/125614

An object of the present invention is to solve the above problems and provide a rubber composition and a pneumatic tire that have self-healing properties.

The present invention provides a diene rubber modified with an ionic functional group 1, an ionic functional group 2 having an opposite charge to the ionic functional group 1, and an SP value of 9.0 to 13.0. The present invention relates to a rubber composition containing a certain ionic compound.

It is preferable that the diene rubber and/or the ionic compound contain at least one member selected from the group consisting of a nitrogen atom and a heterocycle.

It is preferable that the diene rubber and/or the ionic compound contain a nitrogen atom and a heterocycle.

The diene rubber is preferably at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene rubber.
The rubber composition is preferably for use in tires.

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

According to the present invention, a diene rubber modified with an ionic functional group 1, an ionic functional group 2 having an opposite charge to the ionic functional group 1, and an SP value of 9.0 to 13. Since it is a rubber composition containing an ionic compound that is zero, it is possible to provide a rubber composition and a pneumatic tire that have self-healing properties.

The rubber composition of the present invention comprises a diene rubber modified with an ionic functional group 1 and an ionic functional group 2 having an opposite charge to the ionic functional group 1 (where the ionic functional group is an anionic functional group). In this case, the ionic functional group 2 is a cationic functional group, and when the ionic functional group is a cationic functional group, the ionic functional group 2 is an anionic functional group. and ionic compounds having a value of 9.0 to 13.0. As a result, self-healing properties can be imparted, and durability such as crack resistance and various tire physical properties can be maintained for a long period of time.

Although the reason why such self-repairing properties are exhibited is not clear, it is inferred as follows.
When a diene rubber modified with an ionic functional group 1 having opposite electrical properties and an ionic compound having an oppositely charged ionic functional group 2 are combined, the anions present in the diene rubber When the cationic (or cationic) functional group and the cationic (or anionic) compound form ionic bonds, many reversible ionic bonds are formed in the rubber. In the case of a covalent bond, once it is broken, it cannot be restored, but in the case of an ionic crosslink (bond), it is a reversible bond, so even if it is broken, it will recombine and be repaired. It is presumed that such reversible bonds are incorporated into the polymer crosslinks and recombine even after being broken, resulting in self-healing properties.

Ionic functional groups (ionic functional group 1 of diene rubber, ionic functional group 2 of ionic compounds) include anionic functional groups and cationic functional groups, for example, ionic functional group 1 When is an anionic functional group, ionic functional group 2 is a cationic functional group having an opposite charge, and when ionic functional group 1 is a cationic functional group, ionic functional group 2 is this It is an anionic functional group with an opposite charge. The number of ionic functional groups 1 and 2 in the diene rubber or ionic compound may be one or more.

Examples of anionic functional groups include halogen groups and acidic functional groups. Examples of the halogen group include a fluoro group, a chloro group, a bromo group, and an iodo group. Examples of acidic functional groups include carboxylic acid groups, sulfonic acid groups, sulfuric acid groups, phosphonic acid groups, phosphoric acid groups, phosphinic acid groups, maleic acid groups, acid anhydride groups (maleic anhydride, etc.), fumaric acid groups, and itacon. Examples include acid groups, acrylic acid groups, methacrylic acid groups, and mercapto groups. Among these, from the viewpoint of self-healing properties, halogen groups and carboxylic acid groups are preferred, and carboxylic acid groups are more preferred.

Examples of the cationic functional group include basic functional groups. Examples of the basic functional group include an amino group, an imino group (=NH), an ammonium base, and a heterocyclic group having a basic nitrogen atom. The amino group may be a primary amino group (-NH ₂ ), a secondary amino group (-NHR), or a tertiary amino group (-NRR'). The R and R' are an alkyl group, a phenyl group, an aralkyl group, etc., and preferably have 1 to 8 carbon atoms. Examples of ammonium bases include tertiary ammonium bases and quaternary ammonium bases. Examples of the heterocyclic group having a basic nitrogen atom include nitrogen-containing heterocyclic groups such as a pyridine group, a pyrimidine group, a pyrazine group, an imidazole group, an imidazole group containing a thiol, a triazole group, and a thiazole group. In the case of a heterocyclic group, having a double bond makes it easier to disperse in rubber. Among these, from the viewpoint of self-healing properties, pyridine groups, imidazole groups, thiazole groups, and amino groups (amine groups) are preferred.

A diene rubber modified with an ionic functional group 1 and/or an ionic compound having an ionic functional group 2 having an opposite charge to the ionic functional group 1 and having a predetermined SP value can self-repair. From the viewpoint of properties, it is preferable to contain at least one member selected from the group consisting of a nitrogen atom and a heterocycle, and more preferably to contain both a nitrogen atom and a heterocycle. Here, examples of the heteroatom of the heterocycle include a nitrogen atom, an oxygen atom, a sulfur atom, etc., and a nitrogen atom is preferable.

The diene rubber is modified with an ionic functional group 1, and the content of the ionic functional group 1 in 100% by mass of the diene rubber is preferably 0.5% by mass or more, and 0.5% by mass or more. The content is more preferably 8% by mass or more, and even more preferably 1.0% by mass or more. By setting it above the lower limit, sufficient ionic bonding parts are formed and the expected self-healing properties tend to be obtained. The upper limit is not particularly limited, but is preferably 40% by mass or less, more preferably 35% by mass or less.
Note that the content of the ionic functional group 1 can be measured by performing NMR measurement and calculating the content (mass %) based on the peak corresponding to the ionic functional group 1.

Examples of the diene rubber constituting the diene rubber modified with the ionic functional group 1 include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), and the like. Isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. The rubber components may be used alone or in combination of two or more. Among these, from the viewpoint of tire physical properties, SBR, BR, and isoprene rubber are preferred, and SBR and BR are more preferred.

Regarding the ionic functional group 1 in the diene rubber, from the viewpoint of imparting good self-healing properties and maintaining durability such as crack resistance and various tire physical properties for a long period of time, the anionic functional group 1 is an acidic functional group. A functional group is preferred, and a carboxylic acid group is more preferred. Further, as the cationic functional group, an amino group (amine group), an imino group, an ammonium base, and a heterocyclic group having a basic nitrogen atom are preferable, and an amino group (amine group) and a pyridine group are more preferable.

In addition, from the viewpoint of maintaining durability such as crack resistance and various tire physical properties for a long period of time, a diene rubber modified with ionic functional group 1 (opposite charge to ionic functional group 2 of the ionic compound) is used. In this case, it is preferable to further include a diene rubber modified with an ionic functional group having an opposite charge to the ionic functional group 1. That is, it is preferable to include both rubber components: a diene rubber modified with an anionic functional group and a diene rubber modified with a cationic functional group.

When using SBR (diene rubber) modified with ionic functional group 1, the content of modified SBR (SBR modified with ionic functional group 1) in 100 mass% of the rubber component is 5% by mass or more. It is preferably 10% by mass or more, more preferably 15% by mass or more. By setting it above the lower limit, good crack resistance (self-repairability) tends to be obtained. The upper limit is not particularly limited and may be 100% by mass, but preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. By setting it below the upper limit, good workability tends to be obtained.

When using BR (diene rubber) modified with ionic functional group 1, the content of modified BR (BR modified with ionic functional group 1) in 100 mass% of the rubber component is 5% by mass or more. It is preferably 10% by mass or more, more preferably 15% by mass or more. By setting it above the lower limit, good crack resistance (self-repairability) tends to be obtained. The upper limit is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less. By setting it below the upper limit, good workability tends to be obtained.

When using isoprene-based rubber (diene-based rubber) modified with ionic functional group 1, the content of the modified isoprene-based rubber (isoprene-based rubber modified with ionic functional group 1) in 100% by mass of the rubber component. is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. By setting it above the lower limit, good crack resistance (self-repairability) tends to be obtained. The upper limit is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less. By setting it below the upper limit, good workability tends to be obtained.

In addition, when the ionic functional group 2 of the ionic compound is a cationic functional group, the content of the diene rubber modified with the ionic functional group 1 is the same as that of the diene rubber modified with the anionic functional group 1. If the ionic functional group 2 is an anionic functional group, the content of the diene rubber modified with the ionic functional group 1 is the content of the diene rubber modified with the cationic functional group 1. content.

The ionic compound having an ionic functional group 2 having an opposite charge to the ionic functional group 1 and having a predetermined SP value has an SP value of from 9.0 to 13.0, preferably from 9.1 to 12.5, more preferably 9.2 to 12.0, even more preferably 9.3 to 11.8. If it is within the above range, the compatibility with the ionic functional group-modified diene rubber will be high, and the expected self-healing properties will tend to be obtained.

Note that in this specification, the SP value means a solubility parameter calculated by the Hoy method based on the structure of the compound. The Hoy method is, for example, K. L. Hoy “Table of Solubility Parameters”, Solvent and Coatings Materials Research and Development Department, Union Carbites Corp. (1985).

The content of the ionic compound is preferably 1.0 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. By setting it above the lower limit, sufficient ionic bonding parts are formed and the expected self-healing properties tend to be obtained. The content is preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, still more preferably 6.0 parts by mass or less. By setting it below the upper limit, for example, bleeding of an excessive amount of the heterocyclic compound from the rubber is suppressed, the recombination of ionic bonding parts is promoted, and the expected self-healing property tends to be obtained.

The ionic compounds include anionic compounds, cationic compounds, etc. The anionic compounds include the aforementioned compounds having anionic functional groups, and the cationic compounds include the aforementioned cationic functional groups. Examples include compounds having groups. Among these, the anionic functional group of the ionic compound is preferably an acidic functional group, from the viewpoint of imparting good self-healing properties and maintaining durability such as crack resistance and various tire physical properties for a long period of time. A carboxylic acid group is more preferred. In addition, the cationic functional group is preferably an amino group (amine group), an imino group, an ammonium base, or a heterocyclic group having a basic nitrogen atom; are more preferred, and even more preferred are an amino group (amine group), a pyridine group, an imidazole group, and a thiazole group.

Examples of anionic compounds include dicarboxylic acids, specifically aliphatic dicarboxylic acids (adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, etc.); aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, etc.); acids, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, etc.); alicyclic dicarboxylic acids (1,4-cyclohexane dicarboxylic acids, etc.); and the like. Among these, from the viewpoint of good crack resistance (self-healing properties), aliphatic dicarboxylic acids are preferred, and suberic acid, adipic acid, sebacic acid, and dodecanedioic acid are more preferred.

Specific examples of cationic compounds include imidazoles (imidazole, N-isobutylimidazole, 1-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-n-propylimidazole, 2-isopropylimidazole, 1-butyl Imidazole, 2-butylimidazole, 2-phenylimidazole, 4-methylimidazole, 4-ethylimidazole, 4-nitroimidazole, 4-phenylimidazole, 2-methyl-4-phenylimidazole, 4,5-dimethylimidazole, 1- isobutyl-2-methylimidazole, 2,4,5-trimethylimidazole, 2,4,5-triphenylimidazole, benzimidazole, 2-methylbenzimidazole, 2-phenylbenzimidazole, etc.); Pyridines (pyridine, 2- Isobutylpyridine, 3-isobutylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 4-propylpyridine, 2-n-hexylpyridine, 3-n-hexyl Pyridine, 3,5-dimethylpyridine, 3,5-diethylpyridine, 2,6-di-tert-butylpyridine, 2-benzylpyridine, 4-benzylpyridine, 2-phenylpyridine, 3-phenylpyridine, 4-phenyl pyridine, 2,6-diphenylpyridine, 2-(3-phenylpropyl)pyridine, 4-(3-phenylpropyl)pyridine, etc.); thiazoles (thiazole, 2-aminothiazole, 2-methylthiazole, 2-methoxythiazole) , 2-ethoxythiazole, 2-isobutylthiazole, 2-trimethylsilylthiazole, 5-trimethylsilylthiazole, 4-methylthiazole, 4,5-dimethylthiazole, 2-ethylthiazole, 2,4-dimethylthiazole, 2-amino-5 -Methylthiazole, 2-amino-4-methylthiazole, 2,4,5-trimethylthiazole, benzothiazole, 2-methylbenzothiazole, 2,5-dimethylbenzothiazole, etc.); alkylene diamines (methylene diamine, ethylene diamine, Polyamines (diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc.); and the like. Among these, methylimidazole, butylimidazole, pyridine, and ethylenediamine are preferred from the viewpoint of good crack resistance (self-healing properties).

It is preferable that the rubber composition contains a filler.
Examples of fillers include those known in the rubber field, such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica. Among them, silica and carbon black are preferred.

Examples of the silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), and the like. Among these, wet process silica is preferred because it has a large number of silanol groups.

The content of silica is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, based on 100 parts by mass of the rubber component. By setting it above the lower limit, good wet grip performance tends to be obtained. The upper limit of the content is not particularly limited, but is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less. When the content is below the upper limit, good crack resistance (self-repairability) tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 30 m ² /g or more, more preferably 100 m ² /g or more, and still more preferably 125 m ² /g or more. By setting it above the lower limit, there is a tendency for tire physical properties such as good wet grip performance to be obtained. Further, the N ₂ SA of silica is preferably 300 m ² /g or less, more preferably 250 m ² /g or less, and even more preferably 200 m ² /g or less. By setting the amount below the upper limit, good dispersibility tends to be obtained.
Note that the N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

It is preferable that the rubber composition for a tread contains a silane coupling agent together with silica.
The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, Bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis( 3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) ) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide types such as triethoxysilylpropyl methacrylate monosulfide, mercapto types such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane, vinyl types such as vinyltriethoxysilane and vinyltrimethoxysilane, and 3-amino Amino type such as propyltriethoxysilane, 3-aminopropyltrimethoxysilane, glycidoxy type such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, Examples include nitro types such as 3-nitropropyltriethoxysilane, and chloro types such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, for example, products manufactured by Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Kasei Kogyo Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among these, sulfide-based and mercapto-based silane coupling agents are preferred.

When containing a silane coupling agent, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass, based on 100 parts by mass of silica. The amount is more preferably 15 parts by mass or less.

Examples of carbon black include GPF, FEF, HAF, ISAF, SAF, etc., but are not particularly limited. Commercially available products include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kayaku Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can. By blending carbon black, reinforcing properties can be obtained and wear resistance etc. can be significantly improved.

The content of carbon black is preferably 1.0 parts by mass or more, more preferably 3.0 parts by mass or more, based on 100 parts by mass of the rubber component. By setting the content above the lower limit, the effect of incorporating carbon black tends to be obtained. Further, the content of the carbon black is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 10 parts by mass or less. By setting the amount below the upper limit, good dispersibility tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² /g or more, more preferably 80 m ² /g or more, and still more preferably 100 m ² /g or more. When it is at least the lower limit, good reinforcing properties tend to be obtained. The upper limit of N ₂ SA of carbon black is not particularly limited, but is preferably 150 m ² /g or less, more preferably 130 m ² /g or less, even more preferably 125 m ² /g or less.
Note that the nitrogen adsorption specific surface area of carbon black is determined by method A of JIS K6217.

Preferably, the rubber composition contains oil.
Examples of the oil include process oil, vegetable oil, or a mixture thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Among these, process oils are preferred, and aromatic process oils are particularly preferred.

The oil content is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, and preferably 50 parts by mass or less, more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 30 parts by mass or less, more preferably 20 parts by mass or less. Note that the oil content also includes the amount of oil (extended oil) contained in the rubber (oil extended rubber).

The rubber composition may contain resin.
The resin is not particularly limited as long as it is commonly used in the tire industry, and examples include rosin resin, coumaron indene resin, α-methylstyrene resin, terpene resin, pt-butylphenolacetylene resin, and acrylic resin. resin, C5 resin, C9 resin, etc. Commercially available products include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nippon Chemical Co., Ltd., and Japan Co., Ltd. Catalysts made by JXTG Energy Corporation, Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., Toagosei Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

When containing a resin, its content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass, based on 100 parts by mass of the rubber component. Parts by mass or less.

The rubber composition may also include wax.
The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable waxes and animal waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more. Among these, petroleum wax is preferred, and paraffin wax is more preferred.

As the wax, for example, products manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used.

When containing wax, the content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. More preferably, it is 10 parts by mass or less.

The rubber composition may also include an anti-aging agent.
Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; -isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, etc. p-phenylenediamine-based anti-aging agents; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methylphenol; Monophenolic anti-aging agents such as styrenated phenol; bis-, tris-, and polyphenol-based aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Examples include inhibitors. These may be used alone or in combination of two or more. Among these, p-phenylenediamine type anti-aging agents and quinoline type anti-aging agents are preferred.

As the anti-aging agent, for example, products manufactured by Seiko Kagaku Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis Co., Ltd., etc. can be used.

When containing an anti-aging agent, the content thereof is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. More preferably, it is 5 parts by mass or less.

The rubber composition may contain stearic acid.
As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

When containing stearic acid, its content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 5 parts by mass or less.

The rubber composition may contain zinc oxide.
As zinc oxide, conventionally known ones can be used, such as products from Mitsui Kinzoku Kogyo Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

When containing zinc oxide, its content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 5 parts by mass or less.

The rubber composition may also contain sulfur.
Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc. commonly used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products manufactured by Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Co., Ltd., Nippon Karidome Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

When containing sulfur, its content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. The amount is more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

The rubber composition may also include a vulcanization accelerator.
Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-Benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. Examples include sulfenamide vulcanization accelerators; guanidine vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

When containing a vulcanization accelerator, its content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 7 parts by mass or less.

In addition to the above-mentioned components, the rubber composition may further contain other compounding agents (organic crosslinking agents, etc.) commonly used in the tire industry. The content of these compounding agents is preferably 0.1 to 200 parts by mass based on 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then press-molding the obtained kneaded product.

As for the kneading conditions for kneading each component, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C, and the kneading time is usually 1 to 30 minutes, preferably 2 to 10 minutes. Regarding the conditions for press-molding the kneaded product obtained by kneading, the temperature is usually 140 to 190°C, preferably 150 to 185°C, and the time is usually 1 to 60 minutes, preferably 5 to 30 minutes. .

Examples of the rubber composition include tread (cap tread), sidewall, base tread, undertread, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, etc. It can be used (as a rubber composition for tires) in tire members such as side reinforcing layers of run-flat tires.

The pneumatic tire of the present invention is manufactured by a conventional method using the above rubber composition.
That is, the above-mentioned rubber composition is extruded to match the shape of a tire member such as a tread at an unvulcanized stage, and molded together with other tire members using a normal method on a tire molding machine. Form a vulcanized tire. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

The pneumatic tire may have at least a portion (for example, a tread) made of the rubber composition, or may be entirely made of the rubber composition.

The above pneumatic tires are used as tires for passenger cars, tires for large passenger cars, tires for large SUVs, tires for heavy loads such as trucks and buses, tires for light trucks, tires for motorcycles, racing tires (high performance tires), etc. It is possible. It can also be used for all-season tires, summer tires, studless tires (winter tires), etc.

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

Carboxylic acid-modified SBR: ZEON latex (carboxylic acid group content 30% by mass, anionic functional group-modified SBR)
Amine-modified SBR: Production Example 1 below (amine group content 30% by mass, cationic functional group-modified SBR)
Pyridine-modified SBR: ZEON latex (pyridine group content 4.5% by mass, anionic functional group-modified SBR)
Unmodified SBR: SBR: SBR1502 manufactured by Sumitomo Chemical Co., Ltd.
Carboxylic acid modified BR: Production example 2 below (carboxylic acid group content 20% by mass, anionic functional group modified BR)
Non-denatured BR: BR150B manufactured by Ube Industries, Ltd.
1-Butylimidazole: manufactured by Tokyo Kasei Kogyo (SP value 9.5, cationic compound)
Methylimidazole: manufactured by Tokyo Kasei Kogyo (SP value 10.3, cationic compound)
Pyridine: manufactured by Tokyo Kasei Kogyo (SP value 10.5, cationic compound)
Suberic acid: manufactured by Tokyo Kasei Kogyo (SP value 11.6, anionic compound)
4-Methylthiazole: manufactured by Tokyo Kasei Kogyo (SP value 10.3, cationic compound)
Ethylenediamine: manufactured by Tokyo Kasei Kogyo (SP value 12.2, cationic compound)
Stearic acid: manufactured by Tokyo Kasei Kogyo (SP value 8.4, anionic compound)
Tetramethylethyldiamine: manufactured by Tokyo Kasei Kogyo (SP value 7.8, cationic compound)
Diethylene glycol: manufactured by Tokyo Kasei Kogyo (SP value 14.2, anionic compound)
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA175 m ² /g)
Carbon black: Showblack N220 (N ₂ SA111 m ² /g) manufactured by Cabot Japan Co., Ltd.
Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Oil: Process X140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: Ozonone 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Seiko Kagaku Co., Ltd.
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.

<Manufacture example 1>
In a heat-resistant container that has been sufficiently purged with nitrogen, add 1500 ml of n-hexane, 100 mmol of styrene, 800 mmol of 1,3-butadiene, 5 mmol of p-methoxystyrene, 0.2 mmol of tetramethylethylenediamine, 0.12 mmol of dimethylamine (modifier), and n-butyllithium. 0.12 mmol was added and stirred at 0°C for 48 hours. Thereafter, alcohol was added to stop the reaction, and after adding 1 g of 2,6-tert-butyl-p-cresol to the reaction solution, amine-modified SBR was obtained by reprecipitation purification. The amine group content of the obtained amine-modified SBR was 30% by mass.

<Production example 2>
Butadiene was polymerized in toluene using an n-butyllithium catalyst to obtain polybutadiene. Maleic anhydride was added to the obtained polybutadiene and reacted at 190°C for 4 hours to obtain carboxylic acid-modified BR. The carboxylic acid group content of the obtained carboxylic acid-modified BR was 20% by mass.

[Examples and comparative examples]
According to the formulation shown in each table, the mixture was kneaded for 5 minutes at 150° C. using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. The obtained kneaded product was press-molded at 170° C. for 10 minutes using a 2 mm thick mold to obtain a rubber composition (sheet).

The physical properties of the produced rubber composition were evaluated by the following method. The results are shown in Table 1.

(Evaluation of rubber physical properties)
A sample (rubber composition) was prepared by making an initial cut of 5 mm on both ends of a rubber piece measuring 90 mm (vertical) x 50 mm (horizontal) x 2 mm (thickness). Using a dematcher tester, the prepared sample was repeatedly subjected to elongation fatigue (strain 30%), and the length of the cut was measured every 50,000 deformations to confirm crack growth. The crack length (average of the left and right sides) at the time of 200,000 deformations was compared. Comparative Example 1 was set as 100, and the crack length of each sample was expressed as an index. The larger the index, the better the self-healing property and the better durability such as crack resistance can be imparted.

A diene rubber modified with an ionic functional group 1 such as a carboxylic acid group, an amine group, or a pyridine group, and an imidazole group, a pyridine group, a carboxylic acid group, an amine group, etc. that have an opposite charge to the ionic functional group 1. The rubber composition of the example containing an ionic compound having an ionic functional group 2 and a predetermined SP value has excellent self-healing properties and can provide durability such as good crack resistance. there were.

Claims (7)

A diene rubber modified with an ionic functional group 1,
an ionic compound having an ionic functional group 2 having an opposite charge to the ionic functional group 1 and having an SP value of 9.0 to 13.0 ,
A rubber composition in which the diene rubber modified with the ionic functional group 1 and/or the ionic compound contains a nitrogen atom and a heterocycle . A diene rubber modified with an ionic functional group 1,
A rubber composition comprising an ionic compound having an ionic functional group 2 having an opposite charge to the ionic functional group 1 and having an SP value of 9.0 to 13.0,
A rubber composition further comprising a diene rubber modified with an ionic functional group having an opposite charge to the ionic functional group 1 . 3. The rubber composition according to claim 2 , wherein the diene rubber modified with the ionic functional group 1 and/or the ionic compound contains at least one member selected from the group consisting of a nitrogen atom and a heterocycle. 3. The rubber composition according to claim 2 , wherein the diene rubber modified with the ionic functional group 1 and/or the ionic compound contains a nitrogen atom and a heterocycle. Any one of claims 1 to 4 , wherein the diene rubber constituting the diene rubber modified with the ionic functional group 1 is at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene rubber. The rubber composition according to claim 1. The rubber composition according to any one of claims 1 to 5 , which is used for tires. A pneumatic tire using the rubber composition according to any one of claims 1 to 6 .