JP2013107991A - Rubber composition for tire and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire capable of improving fuel efficiency and abrasion resistance while maintaining good processability, and a pneumatic tire using the rubber composition.SOLUTION: The rubber composition for a tire contains: at least one kind selected from the group consisting of natural rubber and diene-based synthetic rubbers; amino acid surface-treated carbon black obtained by neutralizing acidic groups formed by liquid phase oxidation treatment of carbon black with an amino acid to substitute a part or all of hydrogen atoms of the acidic groups by amino acid salt groups; and an amphoteric compound having acidic and basic functional groups.

Description

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

In recent years, there has been an increasing demand for fuel efficiency for automobiles, and it is known that the rubber physical properties of tires have an important effect on fuel efficiency. Therefore, it is possible to provide a rubber composition for tires with excellent fuel efficiency. It is desired. In general, it is effective to reduce the hysteresis loss of a rubber composition in order to obtain a fuel-saving tire.

As a filler for a tire rubber composition, carbon black is widely used in terms of reinforcement and wear resistance. In order to achieve low fuel consumption by blending carbon black, methods such as increasing the particle size of carbon black and reducing the amount of carbon black are conceivable, but a decrease in wear resistance is inevitable.

On the other hand, it is known that silica can be used to reduce fuel consumption as a filler, but silica compound is inferior in wear resistance and the like as compared with carbon black compound, and it is difficult to obtain sufficient performance.

Patent Document 1 proposes a technique for improving the dispersibility of carbon black by adding a diamine compound and improving low heat buildup. However, there is still room for improvement in terms of improving fuel efficiency while maintaining good wear resistance. There is also a problem that the scorch time is short and the processability is poor.

Patent No. 2912845

The present invention provides a tire rubber composition that can solve the above-mentioned problems and can improve fuel economy and wear resistance while maintaining good processability, and a pneumatic tire using the rubber composition. With the goal.

In the present invention, at least one selected from the group consisting of natural rubber and diene-based synthetic rubber and an acidic group generated by liquid-phase oxidation treatment of carbon black are neutralized with an amino acid, whereby one of hydrogen of the acidic group is obtained. The present invention relates to a rubber composition for tires containing an amino acid surface-treated carbon black partially or entirely substituted with an amino acid base and an amphoteric compound having acidic and basic functional groups.

（式（Ｉ）中、Ｒ^１は、炭素数２〜３０のアルキレン基、アルケニレン基又はアルキニレン基を表す。Ａは、酸性官能基を表す。Ｒ^２及びＲ^３は、同一又は異なって、水素原子、炭素数１〜２０のアルキル基、アルケニル基若しくはアルキニル基、又は炭素数１〜２０のアルコキシシリル基を表す。式（Ｉ）で表される化合物は、該化合物の金属塩でもよい。） The amphoteric compound is preferably a compound represented by the following formula (I).

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent hydrogen. An atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.)

［式（Ｉ−１）中、ｐは２〜８の整数を表す。式（Ｉ−２）中、ｑは２〜８の整数を表す。Ｍ^ｒ＋は金属イオンを表し、ｒはその価数を表す。］ The amphoteric compound is preferably a compound represented by the following formula (I-1) and / or the following formula (I-2).

[In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. M ^{r +} represents a metal ion, and r represents its valence. ]

The metal ion represented by ^{Mr +} in the formula (I-2) is preferably a lithium ion, a sodium ion, a potassium ion, a cesium ion, a cobalt ion, a copper ion, or a zinc ion.

It is preferable that content of the said amino acid surface treatment carbon black is 10-100 mass parts with respect to 100 mass parts of rubber components.

The content of the amphoteric compound is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the amino acid surface-treated carbon black.

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

According to the present invention, at least one selected from the group consisting of natural rubber and diene-based synthetic rubber and an acidic group hydrogen by neutralizing an acidic group generated by liquid phase oxidation treatment of carbon black with an amino acid. Is a rubber composition for tires containing an amino acid surface-treated carbon black partially or entirely substituted with an amino acid base and an amphoteric compound having acidic and basic functional groups, while maintaining good processability Can improve fuel efficiency and wear resistance.

The tire rubber composition of the present invention neutralizes at least one selected from the group consisting of natural rubber (NR) and diene-based synthetic rubber and an acidic group generated by liquid phase oxidation treatment of carbon black with an amino acid. By doing so, it contains an amino acid surface-treated carbon black in which part or all of the hydrogen of the acidic group is substituted with an amino acid base, and an amphoteric compound having acidic and basic functional groups.

When carbon black and an amphoteric compound having both an acidic functional group and a basic functional group are blended with natural rubber or a diene-based synthetic rubber, the acidic functional group of the amphoteric compound reacts with the rubber to produce a basic functional group. Since the group reacts with the carbon black surface, the dispersibility of the carbon black is improved and heat generation can be suppressed by restraining the carbon black. Therefore, the fuel efficiency and wear resistance can be improved in a well-balanced manner. Also, good workability can be obtained.
The amino acid surface-treated carbon black has an acidic group (oxygen-containing hydrophilic functional group) because it is oxidized. Since part or all of the hydrogen of this acidic group is substituted with an amino acid base, it also has a carboxyl group (oxygen-containing hydrophilic functional group) that is an acidic group derived from an amino acid. Thus, the amino acid surface-treated carbon black is an oxygen-containing hydrophilic functional group, together with a carboxyl group that is an acidic group derived from an amino acid, and an acidic group that remains without being neutralized among acidic groups that are generated by oxidation treatment. It also has a group.
In the present invention, since this amino acid surface-treated carbon black is used as carbon black, the reactivity between the basic functional group of the amphoteric compound and the carbon black surface (the oxygen-containing hydrophilic functional group of the amino acid surface-treated carbon black). Thus, the above-mentioned performance improvement effect can be obtained synergistically while maintaining good processability.

In addition, when only the amino acid surface-treated carbon black is blended, fuel economy and wear resistance tend to be reduced as compared with the case of blending ordinary carbon black. In addition, when an amphoteric compound is blended together with normal carbon black, the fuel efficiency tends to improve, but the wear resistance tends to decrease. As described above, when the amino acid surface-treated carbon black and the amphoteric compound are blended alone, the wear resistance tends to decrease. On the other hand, when amino acid surface-treated carbon black and an amphoteric compound are used in combination, the wear resistance, which has been reduced when each of them is added alone, can be improved, and the fuel efficiency can be improved synergistically. The fuel efficiency and wear resistance can be remarkably improved while maintaining excellent processability.

In the present invention, the rubber component is NR, diene synthetic rubber (isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene. Rubber (NBR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), halogenated butyl rubber (X-IIR), etc.) are used. Among these, NR is preferable from the viewpoint of low fuel consumption and mechanical strength, and BR is preferable from the viewpoint of wear resistance and bending crack resistance. Note that NR and BR may be used in combination. A rubber component may be used independently and may use 2 or more types together.

The NR is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20, and the like can be used.

The content of NR in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, and further preferably 40% by mass or more. If it is less than 20% by mass, sufficient fuel economy and rubber strength tend not to be obtained. The upper limit of the content of NR is not particularly limited, and may be 100% by mass. However, when other rubber components are used together with NR, 70% by mass or less is preferable.

The BR is not particularly limited. For example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR150B manufactured by Ube Industries, Ltd., high cis content BR, etc. Commonly used in the tire industry such as BR containing 2-syndiotactic polybutadiene crystal (SPB) can be used. Of these, BR having a cis content of 95% by mass or more is preferred because of its high effect of improving wear resistance. The cis content can be measured by infrared absorption spectrum analysis.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more. When it is less than 5% by mass, sufficient wear resistance tends to be not obtained. The BR content is preferably 70% by mass or less, more preferably 60% by mass or less.

In the present invention, an amino acid surface-treated carbon black in which part or all of the hydrogen of the acidic group is substituted with an amino acid base by neutralizing an acidic group generated by liquid phase oxidation treatment of carbon black with an amino acid is used. .

The amino acid surface-treated carbon black is a carbon black in which part or all of hydrogen of acidic groups such as hydroxyl groups and carboxyl groups generated on the surface of the carbon black by liquid phase oxidation treatment is substituted with an amino acid base.

As described above, the amino acid surface-treated carbon black is an oxygen-containing hydrophilic functional group, together with a carboxyl group that is an acidic group derived from an amino acid, and an acidic group that remains without being neutralized among acidic groups generated by oxidation treatment. It also has a group (carboxyl group, hydroxyl group, etc.).
Examples of the oxygen-containing hydrophilic functional group include, in addition to the hydroxyl group and the carboxyl group, an alkali metal salt of a carboxyl group, and the like. However, the reactivity with the basic functional group of the amphoteric compound is high, and it is used in combination with the amphoteric compound. In this case, a carboxyl group and / or an alkali metal salt thereof is preferable, and a carboxyl group is more preferable because the effect of improving fuel economy and wear resistance is high.

As a method for producing an amino acid surface-treated carbon black, for example, carbon black is subjected to liquid phase oxidation treatment, after the reduction salt is removed after the liquid phase oxidation treatment, the acidic groups generated by the liquid phase oxidation treatment are neutralized with amino acids, Examples thereof include a method of filtering, washing with water, and drying after removing salts generated by neutralization.

The liquid phase oxidation treatment of carbon black is, for example, stirring and mixing a slurry formed by putting carbon black in an aqueous solution of an oxidizing agent such as nitric acid, sulfuric acid, chlorate, persulfate, perborate, and percarbonate. do it. In this case, in the liquid phase oxidation treatment, carbon black is added to the oxidant aqueous solution, and the oxidant concentration, the amount ratio of carbon black, etc. are adjusted, and the time is appropriately set at a temperature of about room temperature to 90 ° C, preferably 50 to 90 ° C. What is necessary is just to carry out by stirring.

In addition, in order to disperse | distribute carbon black uniformly in a slurry, addition of surfactant is also preferable, and any anionic type, nonionic type, and cationic type can be used as a surfactant.

The carbon black subjected to the liquid phase oxidation treatment is not particularly limited, and furnace black, channel black, acetylene black, thermal black and the like can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black to be subjected to the liquid phase oxidation treatment is preferably 40 m ² / g or more, and more preferably 60 m ² / g or more. When N ₂ SA is less than 40 m ² / g, the wear resistance improving effect tends to be small. Also, _N 2 SA of the carbon black to be liquid-phase oxidation process is preferably 200 meters ² / g or less, more preferably ^{150m 2 / g, 100m 2 /} g or less is more preferable. When N ₂ SA exceeds 200 m ² / g, the dispersibility of the amino acid surface-treated carbon black tends to decrease, and the wear resistance and fuel efficiency tend to decrease.
In the present specification, the nitrogen adsorption specific surface area of carbon black is determined according to JIS K 6217-2: 2001.

By the liquid phase oxidation treatment, hydrophilic acidic groups (oxygen-containing hydrophilic functional groups) such as carboxyl groups and hydroxyl groups are generated on the surface of the carbon black particles.

Acidic groups such as carboxyl groups and hydroxyl groups on the surface of carbon black produced by liquid phase oxidation treatment are neutralized, but before the neutralization treatment, the reducing salts in the slurry produced by liquid phase oxidation treatment are removed. By doing so, the neutralization reaction can proceed smoothly and efficiently. The reduction salt may be removed using a separation membrane such as an ultrafiltration membrane (UF), a reverse osmosis membrane (RO), or an electrodialysis membrane.

Next, the slurry from which the reducing salt has been removed is neutralized with an amino acid. By this neutralization treatment, part or all of the acidic group hydrogen is replaced with an amino acid base to form a basic amino acid salt compound.

Examples of amino acids include acidic amino acids such as aspartic acid and glutamic acid; neutral amino acids such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, asparagine, glutamine, proline, phenylalanine, tyrosine, and tryptophan; arginine, Examples include basic amino acids such as ortinin, lysine and histidine; those obtained by introducing a substituent into the alkyl group of these amino acids. Examples of the substituent include a substituted or unsubstituted alkyl group, a hydroxyl group, a halogen atom, and a phenyl group. Of these, basic amino acids are preferable, and arginine and lysine are more preferable.

The neutralization treatment may be performed at room temperature, but in order to smoothly proceed with the neutralization reaction, an amino acid is added while stirring the slurry, and the temperature; room temperature to 100 ° C., time; 3 to 20 hours, pH; It is preferable to adjust to 0-12.0.

It is preferable to purify and remove the salts produced by the neutralization treatment. Purification may be performed by removing salts using a separation membrane such as an ultrafiltration membrane (UF), a reverse osmosis membrane (RO), and an electrodialysis membrane. Moreover, it is preferable to refine | purify the grade of refinement | purification until the electrical conductivity of a slurry is set to 5 mS / cm or less, for example by making content concentration of carbon black 20 mass%.

The purified slurry may have large undispersed lumps and coarse particles, and the large undispersed lumps and coarse particles may be classified and removed by a method such as centrifugation or filtration.

The obtained slurry is filtered, washed with water, and dried to obtain amino acid surface-treated carbon black. Drying may be performed, for example, at 50 to 200 ° C. (preferably 100 to 160 ° C.) for 5 to 50 hours (preferably 15 to 30 hours).

In the rubber composition of the present invention, the content of the amino acid surface-treated carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. is there. If it is less than 10 mass parts, there exists a tendency which cannot fully improve a fuel-consumption property and abrasion resistance. The content of the amino acid surface-treated carbon black is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less. If it exceeds 100 parts by mass, the workability may be significantly reduced. In addition, the dispersibility of the amino acid surface-treated carbon black tends to decrease, and the wear resistance and fuel efficiency tends to decrease.

The tire rubber composition of the present invention may use carbon black other than amino acid surface-treated carbon black together with amino acid surface-treated carbon black. Examples of carbon black that can be used include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited.

In the present invention, an amphoteric compound having an acidic functional group and a basic functional group is used. Examples of acidic functional groups include carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, thiosulfonic acid groups (—SSO ₃ H), dithiocarboxylic acid groups (—CSSH), and thioalkylcarboxylic acids having an alkyl group having 1 to 20 carbon atoms. Examples include an acid group (-SRCOOH: R is a linear or branched alkyl group), a phenolic hydroxyl group, and the like, and among them, a thiosulfonic acid group is preferable. Examples of basic functional groups include primary amino groups, secondary amino groups, and tertiary amino groups. The amphoteric compound may be a metal salt of the compound.

As the amphoteric compound, a compound represented by the following formula (I) can be preferably used.

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent hydrogen. An atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.)

The functional group part containing nitrogen of the formula (I) reacts with an oxygen-containing hydrophilic functional group such as a carboxyl group present on the surface of the amino acid surface-treated carbon black to bind to the amino acid surface-treated carbon black, thereby forming an acidic functional group part. Reacts with the double bond of the polymer. Therefore, since the polymer is restrained by the reaction, the exothermic property can be suppressed. Therefore, fuel economy and wear resistance can be improved in a well-balanced manner.

The carbon number of the alkylene group, alkenylene group, and alkynylene group of R ¹ is preferably 2 to 18, more preferably 2 to 12. R ¹ may be linear or branched, and specific examples of the alkylene group include ethylene group, propylene group, butylene group, and specific examples of the alkenylene group include vinylene group, propenylene group, butenylene group, etc. Specific examples of the alkynylene group include an ethynylene group, a propynylene group, and a butynylene group. R ¹ is preferably an alkylene group.

Examples of the acidic functional group for A include the same ones described above. Examples of the alkyl group having 1 to 20 carbon atoms of R ² and R ³ include a methyl group, an ethyl group, a propyl group, and a butyl group. An ethynyl group, a propynyl group, a butynyl group, etc. are mentioned, As a C1-C20 alkoxysilyl group, a triethoxysilyl group, a trimethoxysilyl group, etc. are mentioned. R ² and R ³ are preferably a hydrogen atom.

［式（Ｉ−１）中、ｐは２〜８の整数を表す。式（Ｉ−２）中、ｑは２〜８の整数を表す。Ｍ^ｒ＋は金属イオンを表し、ｒはその価数を表す。］ In the present invention, as the amphoteric compound, it is preferable to use a compound represented by the following formula (I-1) and / or a compound represented by the following formula (I-2).

[In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. M ^{r +} represents a metal ion, and r represents its valence. ]

The compound represented by the above formula (I-2) can be produced by any known method. For example, a method of reacting a haloalkylamine with sodium thiosulfate, a method of reacting a potassium salt of phthalimide and a dihaloalkane with sodium thiosulfate, and hydrolyzing the resulting compound. Can be mentioned.

Specifically, when q is a compound of 6, a method of reacting 6-halohexylamine with sodium thiosulfate, a compound obtained by reacting a potassium salt of phthalimide and 1,6-dihalohexane, and thiosulfuric acid Examples include a method of reacting with sodium and hydrolyzing the obtained compound.

When q is a compound of 3, a method of reacting 3-halopropylamine and sodium thiosulfate, a compound obtained by reacting potassium salt of phthalimide and 1,3-dihalopropane, and sodium thiosulfate And a method of hydrolyzing the resulting compound.

The compound represented by the above formula (I-1) can be produced, for example, by reacting the compound represented by the above formula (I-2) with a protonic acid.

In the present invention, a mixture of compounds represented by formulas (I-1) and (I-2) can also be used. The mixture is obtained by mixing a compound represented by the formula (I-1) and a compound represented by the formula (I-2), a metal-containing hydroxide, carbonate, and carbonic acid represented by the above M. A method of metallizing a part of the compound represented by the formula (I-1) using a hydrogen salt or the like, a method of neutralizing a part of the compound represented by the formula (I-2) using a proton acid Can be manufactured. The compounds represented by the formulas (I-1) and (I-2) thus produced can be removed from the reaction mixture by operations such as concentration and crystallization, and the extracted formula (I-1 ), The compound represented by (I-2) usually contains about 0.1 to 5% of water. In the present invention, only the compound represented by the formula (I-1) or only the compound represented by the formula (I-2) can be used. Furthermore, the compound represented by multiple types of compound represented by Formula (I-1) and the compound represented by Formula (I-2) can also be used together.

In formula (I-1), p represents an integer of 2 to 8, preferably 2 to 5. In formula (I-2), q represents an integer of 2 to 8, and preferably 2 to 5.

As the metal ion represented by ^{Mr +} , lithium ion, sodium ion, potassium ion, cesium ion, cobalt ion, copper ion and zinc ion are preferable, lithium ion, sodium ion and potassium ion are more preferable, and sodium ion is more preferable. . r represents the valence of the metal ion, and is not limited as long as it is a possible range for the metal. In general, r is 1 when the metal ion is an alkali metal ion, 2 or 3 when the metal ion is cobalt ion, an integer of 1 to 3 when the metal ion is copper ion, and 2 when the metal ion is zinc ion. According to the said manufacturing method, although the sodium salt of the compound represented by a formula (I-1) is obtained normally, it can convert into another metal salt by performing a cation exchange reaction.

The median diameter of the compounds represented by the above formulas (I-1) and (I-2) is preferably in the range of 0.05 to 100 μm, more preferably in the range of 1 to 100 μm. The median diameter can be measured by a laser diffraction method.

The compounds represented by the above formulas (I-1) and (I-2) may be used after being previously mixed with a carrier. Examples of the supporting agent include “inorganic fillers and reinforcing agents” described on pages 510 to 513 of “Rubber Industry Handbook <Fourth Edition>” edited by the Japan Rubber Association. Among them, carbon black, silica, calcined Clay and aluminum hydroxide are preferred. Although the usage-amount of a support agent is not specifically limited, The range of 10-1000 mass parts is with respect to 100 mass parts of total amounts of the compound represented by the said formula (I-1) and / or (I-2). preferable.

In the rubber composition of the present invention, the content of the amphoteric compound is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, further preferably 100 parts by mass of the amino acid surface-treated carbon black. 0.5 parts by mass or more. If the amount is less than 0.01 parts by mass, the effect of improving the fuel efficiency is low, and the fuel efficiency and wear resistance may not be sufficiently improved. Moreover, this content becomes like this. Preferably it is 30 mass parts or less, More preferably, it is 15 mass parts or less, More preferably, it is 10 mass parts or less. Even if it exceeds 30 mass parts, the further improvement effect of low-fuel-consumption property is not acquired, but there exists a tendency for workability to fall.

In addition to the above 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 silica and clay, silane coupling agents, zinc oxide, and stearic acid. Further, processing aids, various anti-aging agents, softeners such as oil, vulcanizing agents such as wax and sulfur, vulcanization accelerators, and the like can be appropriately blended.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Is mentioned. Of these, sulfenamide vulcanization accelerators are preferred.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N And '-dicyclohexyl-2-benzothiazolylsulfenamide (DZ). Of these, TBBS is preferable.

The content of the vulcanization accelerator is preferably 0.2 parts by mass or more, more preferably 0.6 parts by mass or more, and preferably 3 parts by mass or less, more preferably 100 parts by mass of the rubber component. Is 2 parts by mass or less. By adjusting within the above range, it is possible to prepare a rubber excellent in performance balance between low fuel consumption and wear resistance.

The oil content 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 it is less than 1 part by mass, the processability is inferior, and the fuel efficiency and wear resistance tend to decrease. The oil content is preferably 15 parts by mass or less, more preferably 8 parts by mass or less. If it exceeds 15 parts by mass, wet grip properties and wear resistance may be deteriorated.

The rubber composition of the present invention can be suitably used for treads (cap treads), base treads, under treads, sidewalls, clinch, inner liners and the like.

As a method for producing the rubber composition for a tire of the present invention, a known method can be used, for example, the above components are kneaded using a rubber kneader such as an open roll, a Banbury mixer, a closed kneader, Thereafter, it can be produced by a vulcanization method.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, a rubber composition containing various additives as necessary is extruded in accordance with the shape of the tire member at an unvulcanized stage, molded by a normal method on a tire molding machine, After bonding together with the tire member to form an unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

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 the production examples will be described together.
3-bromopropylamine hydrobromide: manufactured by Kanto Chemical Co., Ltd. Sodium thiosulfate pentahydrate: manufactured by Kanto Chemical Co., Ltd. phthalimide potassium: manufactured by Kanto Chemical Co., Ltd. dimethylformamide: manufactured by Kanto Chemical Co., Ltd. 1,6-dibromohexane: hydrazine monohydrate manufactured by Kanto Chemical Co., Ltd .: manufactured by Kanto Chemical Co., Ltd.

(Production Example 1 S- (3-aminopropyl) thiosulfuric acid (amphoteric compound A))
To a reaction vessel substituted with nitrogen gas, 75 g of 3-bromopropylamine hydrobromide, 85.26 g of sodium thiosulfate pentahydrate, 375 ml of methanol and 375 ml of water were added, and the mixture was refluxed at 70 ° C. for 5 hours. did. After allowing to cool, methanol was removed under reduced pressure. To the residue was added 13.68 g of sodium hydroxide, and the mixture was stirred at room temperature for 1 hour, and then the solvent was removed under reduced pressure. 600 ml of ethanol was added to the obtained residue and refluxed for 1.5 hours. Hot filtration was performed, and the filtrate was concentrated under reduced pressure to obtain crystals. The crystals were taken out by filtration, washed with ethanol, and further washed with hexane. The obtained crystals were vacuum-dried to obtain sodium S- (3-aminopropyl) thiosulfate.
52 g of sodium S- (3-aminopropyl) thiosulfate, 90 ml of water and 5 mol / l hydrochloric acid were added to the reaction vessel substituted with nitrogen gas, and the resulting solution was concentrated under reduced pressure, and the crystals were taken out by filtration. The obtained crystals were vacuum-dried to obtain S- (3-aminopropyl) thiosulfuric acid.

(Production Example 2 S- (6-Aminohexyl) thiosulfuric acid (amphoteric compound B))
To the reaction vessel, 99.2 g of potassium phthalimide and 480 ml of dimethylformamide were added. To this mixture, a mixture of 200 g of 1,6-dibromohexane and 200 ml of dimethylformamide was added dropwise at room temperature. After completion of the dropwise addition, the resulting mixture was heated to 120 ° C. and refluxed for 5 hours. After standing to cool, the solvent was distilled off from the reaction mixture. Ethyl acetate and water were added for liquid separation, and then the organic layer was concentrated. Hexane and ethyl acetate were added to the resulting residue to precipitate crystals. The crystals were taken out and dried under vacuum to obtain N- (6-bromohexyl) phthalimide.
To the reaction vessel, 40 g of N- (6-bromohexyl) phthalimide, 32.0 g of sodium thiosulfate pentahydrate, 200 ml of methanol and 200 ml of water were added, and the mixture was refluxed for 5 hours, allowed to cool and then the reaction mixture. The solvent was distilled off. To the obtained residue, 200 ml of ethanol was added and refluxed for 1.5 hours. Hot filtration was performed, and the filtrate was concentrated under reduced pressure to obtain crystals, and then allowed to stand. The crystals were taken out by filtration, washed with ethanol, and further washed with hexane. The obtained crystals were vacuum-dried to obtain 6-phthalimidohexyl thiosulfate sodium salt.
A reaction vessel purged with nitrogen was charged with 20.0 g (54.7 mmol) of sodium salt of 6-phthalimidohexylthiosulfate and 200 ml of ethanol, and 4.25 g (84.8 mmol) of hydrazine monohydrate was added to the resulting mixture. It was dripped. After completion of the dropwise addition, the resulting mixture was stirred at 70 ° C. for 5 hours, and then ethanol was distilled off under reduced pressure. 100 ml of methanol was added to the residue and refluxed for 1 hour. Crystals were obtained by hot filtration, washed with methanol, and vacuum-dried to obtain S- (6-aminohexyl) thiosulfate sodium salt.
26 g of sodium S- (6-aminohexyl) thiosulfate, 45 ml of water and 5 mol / l hydrochloric acid were added to the reaction vessel substituted with nitrogen gas, the resulting solution was concentrated under reduced pressure, and the crystals were taken out by filtration. The obtained crystals were vacuum-dried to obtain S- (6-aminohexyl) thiosulfuric acid.

The median diameter (50% D) of the amphoteric compounds A to B obtained in the above Production Examples 1 and 2 was measured by a laser diffraction method (measurement operation is as follows) using a SALD-2000J type manufactured by Shimadzu Corporation. When measured, the median diameter (50% D) was 66.7 μm. The obtained amphoteric compounds A to B were pulverized and their median diameter (50% D) was adjusted to 14.6 μm and used in the following examples.
<Measurement operation>
Amphoteric compounds A to B are dispersed in a mixed solution of a dispersion solvent (toluene) and a dispersing agent (10% by mass sodium 2-ethylhexyl sulfosuccinate / toluene solution) at room temperature, and the obtained dispersion is irradiated with ultrasonic waves. The dispersion was stirred for 5 minutes to obtain a test solution. The test solution was transferred to a batch cell and measured after 1 minute. (Refractive index: 1.70-0.20i)

(Production Example 3 Carbon Black B (amino acid surface-treated carbon black))
150 g of Seest 3 (N ₂ SA: 79 m ² / g, DBP: 101 ml / 100 g) manufactured by Tokai Carbon Co., Ltd. is added to 3000 ml of 2.0 N ammonium persulfate solution, the reaction temperature is 60 ° C., the reaction time is 10 hours, and the stirring speed is increased. Liquid phase oxidation was performed at 300 rpm. After the reduced salt in the slurry was removed with an ultrafiltration membrane (AHP-1010, manufactured by Asahi Kasei Corporation, molecular weight cut off 50000), L-arginine was added for neutralization.
After neutralization, the remaining salt was separated and purified again with an ultrafiltration membrane (Asahi Kasei Co., Ltd., AHP-1010, molecular weight cut off 50000), and then washed with filtered water. Washing with water was repeated twice or more with warm water 10 times the amount of carbon black. Thereafter, carbon black B (amino acid surface-treated carbon black) was obtained by drying at 130 ° C. for 24 hours.

(Production Example 4 Carbon Black C (Amino Acid Surface Treatment Carbon Black))
Carbon black C (amino acid surface-treated carbon black) was obtained in the same manner as in Production Example 3 except that L-arginine in Production Example 3 was changed to L-lysine.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
NR: TSR20
BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
Carbon Black A: Seast 3 manufactured by Tokai Carbon Co., Ltd. (N ₂ SA: 79 m ² / g, DBP: 101 ml / 100 g)
Carbon black B, C: Amino acid surface-treated carbon black amphoteric compound A obtained in Production Examples 3 and 4 above: S- (3-aminopropyl) thiosulfuric acid (prepared in Production Example 1)
Amphoteric compound B: S- (6-aminohexyl) thiosulfuric acid (prepared in Production Example 2)
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Zinc oxide: Zinc Hua 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Anti-aging agent manufactured by NOF Corporation: NOCRACK 6C (N- (1,3-3-) manufactured by Ouchi Shinsei Chemical Co., Ltd. Dimethylbutyl) -N′-phenyl-p-phenylenediamine)
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Examples and Comparative Examples)
According to the formulation shown in Table 1, materials other than sulfur and a vulcanization accelerator were kneaded for 3 minutes at 160 ° C. using a 1.7 L Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes at 80 ° C. using a biaxial open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition.

The following evaluation was performed about the obtained unvulcanized rubber composition and vulcanized rubber composition. The results are shown in Table 1.

<Measurement of Mooney viscosity>
The unvulcanized rubber composition was measured at 130 ° C. according to the Mooney viscosity measuring method based on JIS K6300. The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 was set to 100, and the results of each formulation were displayed as an index. The larger the index, the lower the Mooney viscosity and the better the processability.

<Viscoelasticity test>
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of each vulcanized rubber composition was measured under the conditions of a temperature of 50 ° C., an initial strain of 10%, and a dynamic strain of 2%. The tan δ of Comparative Example 1 was set to 100, and the index was expressed by the following formula (rolling resistance index). The larger the index, the better the rolling resistance characteristics (low fuel consumption).
(Rolling resistance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) × 100

<Abrasion resistance test>
About the obtained vulcanized rubber composition, the amount of lamborn wear was measured under the conditions of a temperature of 20 ° C., a slip rate of 20%, and a test time of 2 minutes using a lamborn wear tester. Further, the volume loss amount was calculated from the measured amount of lamborn wear, and the volume loss amount of each formulation was displayed as an index with the lamborn wear index of Comparative Example 1 being 100 (Lambourn wear index). It shows that it is excellent in abrasion resistance, so that a Lambourn abrasion index is large.

From the results shown in Table 1, at least one selected from the group consisting of natural rubber and diene-based synthetic rubber, amino acid surface-treated carbon black (carbon black B), and amphoteric compounds having acidic and basic functional groups (amphoteric compounds) Examples containing A and B) were able to improve fuel efficiency and wear resistance while maintaining good processability.

By using the amino acid surface-treated carbon black and the amphoteric compound in combination by comparing Comparative Examples 1, 3, 6, and Example 1, and Comparative Examples 2, 3, 6, and Example 3, each of them was blended alone. In this case, the wear resistance, which has been reduced, can be improved, and the fuel efficiency can be improved synergistically. The fuel efficiency and wear resistance are significantly improved while maintaining good processability. I understood that I could do it.

Claims (7)

At least one selected from the group consisting of natural rubber and diene-based synthetic rubber and part or all of the hydrogen of the acidic group can be obtained by neutralizing the acidic group generated by liquid phase oxidation treatment of carbon black with an amino acid. A rubber composition for tires comprising an amino acid surface-treated carbon black substituted with an amino acid base and an amphoteric compound having acidic and basic functional groups. The tire rubber composition according to claim 1, wherein the amphoteric compound is a compound represented by the following formula (I).

(In the formula (I), R ¹ represents an alkylene group having 2 to 30 carbon atoms, an alkenylene group or an alkynylene group. A represents an acidic functional group. R ² and R ³ are the same or different and represent hydrogen. An atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an alkynyl group, or an alkoxysilyl group having 1 to 20 carbon atoms.The compound represented by the formula (I) may be a metal salt of the compound.) The tire rubber composition according to claim 1, wherein the amphoteric compound is a compound represented by the following formula (I-1) and / or the following formula (I-2).

[In formula (I-1), p represents an integer of 2 to 8. In formula (I-2), q represents an integer of 2 to 8. M ^{r +} represents a metal ion, and r represents its valence. ] The tire rubber according to claim 3, wherein the metal ion represented by ^{Mr +} in the formula (I-2) is a lithium ion, a sodium ion, a potassium ion, a cesium ion, a cobalt ion, a copper ion, or a zinc ion. Composition. The tire rubber composition according to any one of claims 1 to 4, wherein the content of the amino acid surface-treated carbon black is 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component. The tire rubber composition according to any one of claims 1 to 5, wherein a content of the amphoteric compound is 0.01 to 30 parts by mass with respect to 100 parts by mass of the amino acid surface-treated carbon black. A pneumatic tire produced using the rubber composition according to claim 1.