JP2016113590A - Rubber composition for tire, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire in which ozone resistance, color fastness and tire appearance can be improved while maintaining or improving satisfactory reinforcing properties and low fuel consumption properties, and a pneumatic tire using the same.SOLUTION: A rubber composition for a tire contains rubber components, a pluronic type nonionic surfactant, a fatty acid mixture and carbon black, in which the fatty acid mixture includes ricinolic acid and at least one kind selected from the group consisting of linolic acid, oleic acid, palmitic acid and dihydroxystearic acid, and, in which, to 100 pts.mass of the rubber components, the content of the pluronic type nonionic surfactant is 0.1 to 3.0 pts.mass, the content of the fatty acid mixture is 0.1 to 5.0 pts.mass, and the content of the carbon black is 2 to 70 pts.mass.SELECTED DRAWING: None

Description

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

Since an automobile tire uses a rubber composition made of natural rubber or a diene synthetic rubber as a raw material, cracks may occur due to the progress of deterioration in the presence of ozone. In order to suppress the occurrence and progress of cracks in the presence of ozone, for example, an antioxidant (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), poly (2 , 2,4-trimethyl-1,2-) dihydroquinoline (TMDQ), etc.) and additives such as petroleum waxes are blended in the rubber composition.

The anti-aging agent and petroleum wax act to protect rubber from ozone by shifting (blooming) from vulcanized rubber to the surface of rubber such as tires. However, excessive blooming of the anti-aging agent and petroleum wax in a short period of time causes white discoloration. Moreover, the anti-aging agent deteriorated by ozone causes tea discoloration. Similarly, excessive blooming causes brown discoloration. Further, when the wax or the like deposited on the tire surface is uneven, light irregular reflection occurs, brown discoloration due to the deteriorated anti-aging agent becomes more conspicuous, and the tire gloss is lost.

Patent Document 1 describes that deterioration of the appearance of a tire can be prevented by blending an ether type nonionic surfactant of polyoxyethylene. However, there is room for improvement in terms of improving ozone resistance, discoloration resistance, and tire appearance while maintaining or improving good reinforcement and low fuel consumption.

Japanese Patent Laid-Open No. 05-194790

The present invention solves the above-mentioned problems and uses a rubber composition for tires that can improve ozone resistance, discoloration resistance, and tire appearance while maintaining or improving good reinforcement and low fuel consumption, and the same. An object is to provide a pneumatic tire.

The present invention includes a rubber component, a pluronic-type nonionic surfactant, a fatty acid mixture, and carbon black, and the fatty acid mixture includes ricinoleic acid, linoleic acid, oleic acid, palmitic acid, and dihydroxystearic acid. At least one selected from the group, with respect to 100 parts by mass of the rubber component, the content of the pluronic-type nonionic surfactant is 0.1 to 3.0 parts by mass, the content of the fatty acid mixture Relates to a rubber composition for tires in which the content of carbon black is 2 to 70 parts by mass.

The total content of butadiene rubber and isoprene-based rubber in 100% by mass of the rubber component is preferably 80% by mass or more.

The fatty acid mixture preferably contains ricinoleic acid and linoleic acid and / or oleic acid.

The fatty acid mixture is preferably obtained by hydrolyzing castor oil.

The tire rubber composition is preferably a sidewall rubber composition, a clinch rubber composition and / or a wing rubber composition.

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

According to the present invention, since it is a rubber composition for tires containing specific amounts of a pluronic-type nonionic surfactant, a specific fatty acid mixture, and carbon black, good reinforcing properties and low fuel consumption can be maintained or improved. However, ozone resistance, discoloration resistance, and appearance of the tire can be improved, and a pneumatic tire excellent in reinforcement, low fuel consumption, ozone resistance, discoloration resistance, and tire appearance can be provided.

The rubber composition for tires of the present invention includes a rubber component, a pluronic-type nonionic surfactant, a fatty acid mixture, and carbon black, and the fatty acid mixture contains ricinoleic acid, linoleic acid, oleic acid, and palmitic acid. And at least one selected from the group consisting of dihydroxystearic acid, with respect to 100 parts by mass of the rubber component, the content of the pluronic-type nonionic surfactant is 0.1 to 3.0 parts by mass, The content of the fatty acid mixture is 0.1 to 5.0 parts by mass, and the content of the carbon black is 2 to 70 parts by mass.

In the present invention, in the rubber composition containing a specific amount of carbon black, the unevenness of the tire surface (bloom layer) formed by precipitation of wax or the like is smoothed by adding a pluronic type nonionic surfactant. , Irregular reflection of light is suppressed. Furthermore, by blending a specific fatty acid mixture, crystallization of wax or the like in the bloom layer is partially inhibited, and irregular reflection of light by crystals such as fine wax is reduced. By these actions, the discoloration resistance is improved, for example, the above-mentioned brown discoloration and white discoloration are reduced. Furthermore, ozone resistance and discoloration resistance can be improved synergistically by using a pluronic type nonionic surfactant in combination with a specific fatty acid mixture. In addition, the tire appearance is improved by giving the tire surface an appropriate black appearance and gloss. At the same time, good reinforcement (breaking strength) and low fuel consumption can be maintained or improved.

（式（Ｉ）中、ａ、ｂ、ｃは整数を表す。） In the present invention, a pluronic nonionic surfactant is used. Pluronic type nonionic surfactant is also called polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxypropylene block polymer, polypropylene glycol ethylene oxide adduct, and is generally nonionic represented by the following formula (I) It is a surfactant. As represented by the following formula (I), the pluronic-type nonionic surfactant has a hydrophilic group composed of an ethylene oxide structure on both sides, and is composed of a propylene oxide structure so as to be sandwiched between the hydrophilic groups. Has a hydrophobic group.

(In formula (I), a, b, and c represent integers.)

The degree of polymerization of the polypropylene oxide block of the pluronic-type nonionic surfactant (b in the above formula (I)) and the addition amount of polyethylene oxide (a + c in the above formula (I)) are not particularly limited, and the use conditions, purpose, etc. It can be appropriately selected depending on the situation. The higher the proportion of the polypropylene oxide block, the higher the affinity with rubber and the slower the rate of transfer to the rubber surface. Among these, the degree of polymerization of the polypropylene oxide block (b in the above formula (I)) is preferably 100 because the bloom of the nonionic surfactant can be suitably controlled and the effects of the present invention can be more suitably obtained. Or less, more preferably 10 to 70, still more preferably 10 to 60, particularly preferably 20 to 60, and most preferably 20 to 45. Similarly, the addition amount of polyethylene oxide (a + c in the above formula (I)) is preferably 100 or less, more preferably 3 to 65, still more preferably 5 to 55, particularly preferably 5 to 40, most preferably. 10-40. When the degree of polymerization of the polypropylene oxide block and the addition amount of polyethylene oxide are within the above ranges, the bloom of the nonionic surfactant can be suitably controlled, and the effects of the present invention can be more suitably obtained.

Pluronic type nonionic surfactants include BASF Japan's Pluronic series, Sanyo Chemical Industries' New Pole PE series, Asahi Denka Kogyo's Adeka Pluronic L or F series, Daiichi Examples include Epan series manufactured by Kogyo Seiyaku Co., Ltd., Pronon series manufactured by NOF Corporation, and Unilube. These may be used alone or in combination of two or more.

The content of the pluronic nonionic surfactant with respect to 100 parts by mass of the rubber component is 0.1 parts by mass or more, preferably 0.3 parts by mass or more, more preferably 0.6 parts by mass or more, and still more preferably. 0.8 parts by mass or more, particularly preferably 2.0 parts by mass or more. If the amount is less than 0.1 parts by mass, the effects of the present invention may not be sufficiently obtained. Moreover, the said content is 3.0 mass parts or less, Preferably it is 2.9 mass parts or less. If it exceeds 3.0 parts by mass, the reinforcing property, fuel efficiency, tire appearance, steering stability, crack resistance, ozone resistance, and discoloration resistance may be deteriorated.

In the present invention, the above fatty acid mixture is used. By blending the fatty acid mixture in addition to the pluronic ionic surfactant, ozone resistance, discoloration resistance, and tire appearance can be improved while maintaining or improving good reinforcement and low fuel consumption. In addition, in the combination of the above, in ozone resistance and discoloration resistance, the effect of improving performance obtained when only one of the pluronic-type nonionic surfactant and the fatty acid mixture is applied is more than a simple addition. (Synergistic effect) is obtained.

The fatty acid mixture used in the present invention contains at least one selected from the group consisting of linoleic acid, oleic acid, palmitic acid and dihydroxystearic acid in addition to ricinoleic acid. Further, stearic acid, arachidic acid, linolenic acid and the like may be further contained. Especially, it is preferable that ricinoleic acid and linoleic acid and / or oleic acid are included. Thereby, the effect of this invention is acquired more suitably.

The content of ricinoleic acid in 100% by mass of the fatty acid mixture is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more. The content is preferably 92% by mass or less. Within the above range, the effects of the present invention can be obtained better.

When the fatty acid mixture of the present invention contains linoleic acid, the content of linoleic acid in 100% by mass of the fatty acid mixture is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and 3.5 to 5. 2% by mass is more preferable.
When the fatty acid mixture of the present invention contains oleic acid, the content of oleic acid in 100% by mass of the fatty acid mixture is preferably 0.1 to 8% by mass, more preferably 1 to 6% by mass, and 2 to 4.1% by mass. % Is more preferable.
When the fatty acid mixture of the present invention contains palmitic acid, the content of palmitic acid in 100% by mass of the fatty acid mixture is preferably from 0.1 to 4% by mass, more preferably from 0.3 to 2.5% by mass. 5-1.5 mass% is still more preferable.
When the fatty acid mixture of the present invention contains stearic acid, the content of stearic acid in 100% by mass of the fatty acid mixture is preferably 0.1 to 4% by mass, more preferably 0.3 to 2.5% by mass, and 5-1.5 mass% is still more preferable.
When the fatty acid mixture of the present invention contains dihydroxystearic acid, the content of dihydroxystearic acid in 100% by mass of the fatty acid mixture is preferably 0.1 to 4% by mass, more preferably 0.3 to 2.5% by mass, 0.5-1.5 mass% is still more preferable.

The method for producing the fatty acid mixture is not particularly limited, and the fatty acid mixture may be prepared by mixing each fatty acid, but is preferably obtained by hydrolyzing castor oil. There is no restriction | limiting in particular as a method of obtaining a fatty-acid mixture by hydrolyzing a castor oil, A conventionally well-known method can be used. Specific examples include a method of saponifying castor oil with a potassium hydroxide / ethanol solution and purifying the precipitated fatty acid using hydrochloric acid, a method using an enzyme such as lipase, and the like.

Content of a fatty-acid mixture is 0.1 mass part or more with respect to 100 mass parts of rubber components, Preferably it is 0.3 mass part or more, More preferably, it is 0.5 mass part or more. If the amount is less than 0.1 parts by mass, the effects of the present invention may not be sufficiently obtained. Moreover, this content is 5.0 mass parts or less, Preferably it is 4.0 mass parts or less, More preferably, it is 3.0 mass parts or less, More preferably, it is 2.0 mass parts or less. If the amount exceeds 5.0 parts by mass, the initial bloom amount increases and the bloom layer becomes too thick, so that the appearance may be deteriorated, and the reinforcing property, fuel efficiency, ozone resistance, and discoloration resistance also deteriorate. Tend.

In the present invention, the fatty acid mixture is preferably compounded by replacing part or all of stearic acid which has been conventionally blended in a tire rubber composition. Thereby, the effect of this invention is acquired more suitably.
The total content of the fatty acid mixture and stearic acid is preferably 0.5 to 6.0 parts by mass, more preferably 0.7 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component. By making the total content within the above range, the effect of the present invention can be obtained better. Here, stearic acid means stearic acid blended separately from the fatty acid mixture.

In the present invention, a specific amount of carbon black is used. Thereby, favorable reinforcement property, steering stability, crack resistance, and ozone resistance are obtained. Moreover, although there is a concern about deterioration of appearance by blending a large amount of carbon black, in the present invention, deterioration of appearance can be suppressed by setting the content of carbon black to a specific amount. Moreover, the bloom of the said nonionic surfactant and the said fatty-acid mixture can be controlled suitably, and the effect of this invention is acquired favorably.
Specifically, the content of carbon black is 2 parts by mass or more, preferably 15 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 35 parts by mass or more with respect to 100 parts by mass of the rubber component. . If the amount is less than 2 parts by mass, sufficient reinforcement may not be obtained. The content is 70 parts by mass or less, preferably 60 parts by mass or less, more preferably 50 parts by mass or less. If it exceeds 70 parts by mass, the handling stability, fuel efficiency and ozone resistance tend to deteriorate.

Examples of carbon black include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 20 m ² / g or more, and more preferably 30 m ² / g or more. If it is less than 20 m < ² > / g, there exists a possibility that sufficient reinforcement may not be acquired. The _N 2 SA is preferably 180 m ² / g or less, more preferably 120 m ² / g, more preferably ^90m 2 / g or less, ^{60 m} 2 / g or less is particularly preferred. If it exceeds 180 m ² / g, it is difficult to disperse, and the reinforcing property, ozone resistance, steering stability, and crack resistance tend to deteriorate.
Incidentally, _N 2 SA of carbon black, JIS K 6217-2: determined by 2001.

Carbon black has a dibutyl phthalate oil absorption (DBP) of preferably 50 ml / 100 g or more, more preferably 80 ml / 100 g or more, and even more preferably 100 ml / 100 g or more. If it is less than 50 ml / 100 g, sufficient reinforcement may not be obtained. The DBP of carbon black is preferably 200 ml / 100 g or less, more preferably 150 ml / 100 g or less, and further preferably 130 ml / 100 g or less. When it exceeds 200 ml / 100 g, it becomes difficult to disperse, and the reinforcing property, ozone resistance, steering stability, and crack resistance tend to deteriorate.
The DBP of carbon black is measured according to JIS K6217-4: 2001.

In the rubber composition of the present invention, at least one selected from the group consisting of butadiene rubber (BR) and isoprene-based rubber can be suitably used as the rubber component. These may be used alone or in combination of two or more. Among these, isoprene-based rubber is preferable because good reinforcement, ozone resistance, and low fuel consumption can be obtained more preferably, and isoprene-based rubber is more preferably used together with BR.

The rubber composition has a total content of BR and isoprene-based rubber in 100% by mass of the rubber component, preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. If it is less than 80% by mass, the reinforcing property, ozone resistance and fuel efficiency may not be sufficiently obtained. Moreover, the ratio of BR and isoprene-based rubber can be freely designed as long as the reinforcing property, ozone resistance, fuel efficiency and the like are not impaired.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), and modified natural rubber. NR includes deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified natural rubber includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Etc. These may be used alone or in combination of two or more. Among these, NR is preferable because good reinforcement, ozone resistance, and low fuel consumption can be more suitably obtained.

As NR, what is common in tire industry, such as SIR20, RSS # 3, TSR20, can be used, for example. These may be used alone or in combination of two or more.

When the rubber composition contains isoprene-based rubber (particularly NR), the content of isoprene-based rubber in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably. It is 40 mass% or more. The content of the isoprene-based rubber may be 100% by mass, but is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less. When the content of the isoprene-based rubber is within the above range, good reinforcement and low fuel consumption can be obtained more suitably.

As BR, for example, BR730, BR51 manufactured by JSR Corporation, BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B manufactured by Ube Industries, Ltd., BR150B, BR710, etc., high cis content BR, manufactured by Nippon Zeon Co., Ltd. BR1250H and other low cis content BR, Ube Industries, Ltd. VCR412, VCR617, and the like containing 1,2-syndiotactic polybutadiene crystals (SPB) (SPB-containing BR) can be used. These may be used alone or in combination of two or more. Among these, SPB-containing BR is preferable because the effects of the present invention can be obtained more suitably. Moreover, it is more preferable to use BR other than SPB-containing BR (for example, high cis content BR or low cis content BR) and SPB-containing BR in combination because the effect of the present invention can be obtained more suitably.

In the SPB-containing BR, the 1,2-syndiotactic polybutadiene crystal (SPB) is not simply dispersed in the SPB-containing BR, but is chemically bonded to the SPB-containing BR and dispersed in a non-oriented manner. It is preferable. Dispersion after the crystals are chemically bonded to the rubber component tends to suppress the generation and propagation of cracks.

The 1,2-syndiotactic polybutadiene crystal content in the SPB-containing BR is preferably 2.5% by mass or more, and more preferably 8% by mass or more. If it is less than 2.5% by mass, there is a tendency that sufficient hardness (steering stability) of the rubber composition cannot be obtained. The content is preferably 22% by mass or less, more preferably 18% by mass or less, and further preferably 15% by mass or less. The effect of this invention is acquired more suitably as this content rate exists in the said range.

When the said rubber composition contains SPB containing BR, content of SPB containing BR in 100 mass% of rubber components becomes like this. Preferably it is 5 mass% or more, More preferably, it is 15 mass% or more. The content of the SPB-containing BR is preferably 50% by mass or less, more preferably 35% by mass or less. The effect of this invention is acquired more suitably as content of SPB containing BR is in the said range.

When the rubber composition contains BR, the BR content in 100% by mass of the rubber component (the total content of BR when a plurality of BRs are contained) is preferably 20% by mass or more, more preferably 30%. It is at least 40% by mass, more preferably at least 40% by mass. The BR content is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less. When the BR content is within the above range, good reinforcing properties and low fuel consumption can be more suitably obtained.

The rubber component that can be used in addition to BR and isoprene-based rubber is not particularly limited, and is styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), ethylene propylene diene. Examples include diene rubbers such as rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). A rubber component may be used independently and may use 2 or more types together.

In the present invention, it is preferable to add a wax in order to suppress the occurrence and progress of cracks due to ozone. In the present invention, even when a wax is blended, the unevenness of the tire surface (bloom layer) formed by precipitation of the wax or the like can be smoothed as described above. Since irregular reflection of light by the wax crystals is suppressed, the above-mentioned brown discoloration and white discoloration can be reduced, and ozone resistance and discoloration resistance can be improved synergistically. In addition, the tire appearance is improved by giving the tire surface an appropriate black appearance and gloss. Furthermore, in this invention, since it is a specific rubber composition, favorable reinforcement property and low fuel consumption are maintained or improved.

The wax is not particularly limited, and examples thereof include petroleum wax and natural wax. A synthetic wax obtained by refining or chemically treating a plurality of waxes can also be used. These waxes may be used alone or in combination of two or more.

Examples of petroleum waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources. For example, plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax; beeswax, lanolin, whale wax, etc. Animal waxes; mineral waxes such as ozokerite, ceresin, petrolactam; and purified products thereof.

When the rubber composition contains a wax, the content of the wax is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 0.5 parts by mass, sufficient ozone resistance may not be obtained. The wax content is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5.0 parts by mass or less. If the amount exceeds 12 parts by mass, the amount of initial bloom increases and the bloom layer becomes too thick, so the appearance is likely to deteriorate, and further improvement in ozone resistance cannot be expected, and the cost may increase. is there.

The rubber composition of the present invention may contain oil. By blending oil, processability is improved, the tire can be given flexibility, and the effects of the present invention can be obtained better. As the oil, for example, process oil, vegetable oil, or a mixture thereof can be used. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. Specific examples of the paraffinic process oil include PW-32, PW-90, PW-150, and PS-32 manufactured by Idemitsu Kosan Co., Ltd. Specific examples of the aroma-based process oil include AC-12, AC-460, AH-16, AH-24, and AH-58 manufactured by Idemitsu Kosan Co., Ltd. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower 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, paraffinic process oil is preferable because the effects of the present invention can be suitably obtained.

When the rubber composition contains oil, the oil content is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and still more preferably 2. relative to 100 parts by mass of the rubber component. 0 parts by mass or more. The oil content is preferably 60 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. By setting the content of the oil that blooms on the tire surface itself within the above range, the bloom of the nonionic surfactant and the fatty acid mixture can be suitably controlled, and the effects of the present invention can be more suitably obtained. Note that when the oil content exceeds 60 parts by mass, fuel efficiency tends to deteriorate.

The rubber composition of the present invention preferably contains an anti-aging agent in order to suppress the occurrence and progression of cracks due to ozone. In the present invention, as described above, ozone resistance, discoloration resistance, and tire appearance can be improved while maintaining or improving good reinforcement and low fuel consumption as described above even when an anti-aging agent is added.

The anti-aging agent is not particularly limited. For example, naphthylamine, quinoline, diphenylamine, p-phenylenediamine, hydroquinone derivatives, phenol (monophenol, bisphenol, trisphenol, polyphenol), thiobisphenol Series, benzimidazole series, thiourea series, phosphorous acid series, and organic thioacid series antioxidants. These may be used alone or in combination of two or more. Of these, p-phenylenediamine is preferable because ozone resistance is good and the effects of the present invention can be obtained more suitably.

As the p-phenylenediamine-based antioxidant, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylenediamine, N-1, 4-dimethylpentyl-N′-phenyl-p-phenylenediamine, N, N′-diphenyl-p-phenylenediamine, N, N′-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N′- Phenyl-p-phenylenediamine, N, N′-bis (1-methylheptyl) -p-phenylenediamine, N, N′-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N′- Bis (1-ethyl-3-methylpentyl) -p-phenylenediamine, N-4-methyl-2-pentyl-N′-phenyl-p-phenylene Amine, N, N'-diaryl -p- phenylenediamine, hindered mistakes aryl -p- phenylenediamine, phenyl hexyl -p- phenylenediamine, and the like phenyloctyl -p- phenylenediamine. These may be used alone or in combination of two or more. Among these, N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylene is preferred because it has good ozone resistance, the effects of the present invention can be obtained more suitably, and the economy is excellent. Diamine is more preferred.

When the rubber composition contains an anti-aging agent, the content of the anti-aging agent is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. Preferably it is 1.0 mass part or more. If the amount is less than 0.3 parts by mass, sufficient ozone resistance may not be obtained. The content of the anti-aging agent is preferably 10 parts by mass or less, more preferably 6.0 parts by mass or less, and still more preferably 4.0 parts by mass or less. When the amount exceeds 10 parts by mass, the bloom amount of the anti-aging agent increases, and the appearance of the tire may be deteriorated.

The rubber composition of the present invention preferably contains a vulcanization accelerator. Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Etc. These vulcanization accelerators may be used alone or in combination of two or more. Of these, sulfenamide-based vulcanization accelerators are preferable because the effects of the present invention can be obtained more suitably.

Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N -Dicyclohexyl-2-benzothiazolylsulfenamide (DCBS) and the like. These may be used alone or in combination of two or more. Among these, TBBS is preferable because the effects of the present invention can be obtained more suitably.

When the rubber composition contains a vulcanization accelerator, the content of the vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. It is. The content is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less. When the content of the vulcanization accelerator is within the above range, the effect of the present invention can be more suitably obtained.

In the present invention, it is preferable to contain sulfur in order to form an appropriate cross-linked chain in the polymer chain. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. These may be used alone or in combination of two or more.

When the rubber composition contains sulfur, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 1. relative to 100 parts by mass of the rubber component. 0 parts by mass or more. There exists a possibility that the effect of this invention may not fully be acquired as it is less than 0.1 mass part. The sulfur content is preferably 6.0 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 4.0 parts by mass or less, and particularly preferably 3.0 parts by mass or less. If it exceeds 6.0 parts by mass, the reinforcing property, fuel efficiency and ozone resistance may be deteriorated.

In the present invention, as the vulcanizing agent, an alkylphenol / sulfur chloride condensate (for example, tackolol V200 manufactured by Taoka Chemical Co., Ltd.) may be used in addition to sulfur.

In addition to the above components, the rubber composition of the present invention contains, as appropriate, compounding agents generally used in the production of rubber compositions such as silica, silane coupling agents, zinc oxide, stearic acid, and tackifiers. can do.

As a method for producing the rubber composition of the present invention, known methods can be used. For example, the above components are kneaded using a rubber kneader such as an open roll or a Banbury mixer, and then vulcanized. Can be manufactured.

The rubber composition of the present invention constitutes each member of a tire (particularly, the surface (outer surface) of the tire, and is required to have good ozone resistance, discoloration resistance, tire appearance, sidewalls, clinch, and / or Wing etc. can be used suitably.

The side wall is a member arranged on the outside of the case from the shoulder portion to the bead portion. Specifically, in FIG. 1 of JP-A-2005-280612, FIG. 1 of JP-A-2000-185529, and the like. It is a member shown.

The clinch is a rubber portion that covers a contact portion with a rim that exists under the sidewall, and is also called a clinch apex or a rubber chafer. Specifically, it is a member shown in FIG. 1 etc. of Unexamined-Japanese-Patent No. 2008-75066, for example.

The wing is a member located between the tread and the sidewall in the shoulder portion, and specifically, a member shown in FIGS. 1 and 3 of JP-A-2007-176267.

The pneumatic tire of the present invention can be produced by a usual method using the rubber composition.
That is, the rubber composition blended with the above components is extruded in accordance with the shape of sidewalls, clinch, wings, etc. at an unvulcanized stage, and along with other tire members, on a tire molding machine in the usual manner. By molding, an unvulcanized tire can be formed. A tire is obtained by heating and pressurizing the unvulcanized tire in a vulcanizer.

The pneumatic tire of the present invention is used as, for example, passenger car tires, truck / bus tires, motorcycle tires, high-performance tires, and the like. In addition, the high-performance tire in this specification is a tire that is particularly excellent in grip performance, and is a concept that includes a competition tire used in a competition vehicle.

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.
NR: RSS # 3
BR1: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass)
BR2: VCR412 manufactured by Ube Industries, Ltd. (butadiene rubber containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), 1,2-syndiotactic polybutadiene crystal content: 12% by mass)
Carbon Black: Show Black N550 manufactured by Cabot Japan Co., Ltd. (N ₂ SA: 42 m ² / g, DBP oil absorption: 115 ml / 100 g)
Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Oil: Process oil PW-32 (paraffinic process oil) manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Stearic acid surfactant manufactured by NOF Corporation: New Pole PE-64 (Pluronic type nonionic surfactant (PEG / PPG-25 / 30 copolymer) manufactured by Sanyo Chemical Industries Co., Ltd.) (I) a + c: 25, b: 30)
Fatty acid mixture: castor oil manufactured by Wako Pure Chemical Industries, Ltd., saponified with potassium hydroxide / ethanol solution according to a conventional method, and purified fatty acid precipitated using hydrochloric acid (contains each component in 100% by mass of fatty acid mixture) Amount: 87-91% by mass of ricinoleic acid, 3.5-5% by mass of linoleic acid, 2.5-4% by mass of oleic acid, 0.5-1.5% by mass of palmitic acid, 0.5-1% of stearic acid. 5 mass%, dihydroxystearic acid 0.5-1.5 mass%)
Sulfur: Powdered sulfur oxide manufactured by Tsurumi Chemical Co., Ltd .: Zinc Hana No. 1 vulcanization accelerator manufactured by Mitsui Mining & Smelting Co., Ltd .: Noxeller NS (N-tert-butyl manufactured by Ouchi Shinsei Chemical Co., Ltd.) -2-Benzothiazolylsulfenamide)

In accordance with the formulation shown in Table 1, a chemical other than sulfur and a vulcanization accelerator was kneaded to 160 ° C. using a 1.7 L Banbury mixer. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded until reaching 105 ° C., thereby obtaining an unvulcanized rubber composition. Next, the obtained unvulcanized rubber composition was press vulcanized at 160 ° C. for 15 minutes to obtain a vulcanized rubber composition.

The obtained vulcanized rubber composition was evaluated as follows, and the results are shown in Table 1.

<Reinforcing evaluation>
In accordance with JIS K 6251 “Determination of tensile properties of vulcanized rubber and thermoplastic rubber”, a tensile test was conducted using a No. 3 dumbbell, and the elongation at break (EB) of the vulcanized rubber composition and the tensile at break The strength (TB) was measured. In addition, EBxTB of the comparative example 3 was set to 100, and EBxTB of each mixing | blending was each represented as an index | exponent (reinforcing property index) with the following formula. The larger the index, the better the reinforcing property (breaking strength).
(Reinforcing index) = (EB × TB of each formulation) / (EB × TB of Comparative Example 3) × 100

<Low fuel consumption evaluation>
Using a spectrometer manufactured by Ueshima Seisakusho, tan δ of the vulcanized rubber composition was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz, and a temperature of 50 ° C. The reciprocal value of tan δ was displayed as an index (low fuel consumption index) with Comparative Example 3 set to 100. Larger values indicate lower rolling resistance and better fuel efficiency.

<Ozone resistance evaluation>
In accordance with JIS K 6259 “Vulcanized Rubber and Thermoplastic Rubber-Determination of Ozone Resistance”, a test piece of a predetermined size was prepared from the obtained vulcanized rubber composition, and a dynamic ozone deterioration test was performed. . The state of cracking (presence or absence of cracking) after 48 hours of testing under the conditions of reciprocating frequency 0.5 ± 0.025 Hz, ozone concentration 50 ± 5 pphm, test temperature 40 ° C., tensile strain 20 ± 2% Was observed to evaluate the ozone resistance. In addition, the index of the comparative example 3 is set to 100, and the larger the index, the smaller the number of cracks, the smaller the crack size, and the better the ozone resistance.

<Discoloration resistance evaluation>
The sample having finished the ozone resistance test was subjected to a color value difference meter (CR-310) manufactured by Minolta Co., Ltd., and a value and b value were obtained (L ^* a ^* b ^* color system). The index was set to (a ² + b ² ) ^−0.5 and the index of Comparative Example 3 was set to 100 (index of each formulation / index of Comparative Example 3 × 100). A larger index indicates less discoloration and better resistance to discoloration.

<Appearance evaluation>
The sample which finished the ozone resistance test was taken out outdoors, and the appearance was evaluated using the following indices.
◎ Blacker and more glossy than Comparative Example 3 ○ Blacker than Comparative Example 3 and slightly shiny △ Brown equivalent to Comparative Example 3 × Browner than Comparative Example 3

In the examples containing specific amounts of pluronic-type nonionic surfactant, specific fatty acid mixture, and carbon black, ozone resistance, discoloration resistance, and tire resistance are maintained while maintaining or improving good reinforcement and low fuel consumption. It was found that the appearance can be improved.
In addition, comparison between Comparative Examples 1, 2, 4 and Example 2 shows that a specific nonionic surfactant is included as compared with a case where only a specific nonionic surfactant is included or a case where only a specific fatty acid mixture is included. In addition, when the specific fatty acid mixture was used in combination, it was found that an improvement effect (synergistic effect) higher than the addition was obtained in ozone resistance and discoloration resistance.

Claims (6)

A rubber component, a pluronic-type nonionic surfactant, a fatty acid mixture, and carbon black;
The fatty acid mixture comprises ricinoleic acid and at least one selected from the group consisting of linoleic acid, oleic acid, palmitic acid and dihydroxystearic acid;
With respect to 100 parts by mass of the rubber component, the content of the pluronic-type nonionic surfactant is 0.1 to 3.0 parts by mass, the content of the fatty acid mixture is 0.1 to 5.0 parts by mass, A tire rubber composition having a carbon black content of 2 to 70 parts by mass. The tire rubber composition according to claim 1, wherein the total content of butadiene rubber and isoprene-based rubber in 100% by mass of the rubber component is 80% by mass or more. The tire rubber composition according to claim 1 or 2, wherein the fatty acid mixture contains ricinoleic acid and linoleic acid and / or oleic acid. The rubber composition for tires according to any one of claims 1 to 3, wherein the fatty acid mixture is obtained by hydrolyzing castor oil. The rubber composition for tires according to any one of claims 1 to 4, which is a rubber composition for side walls, a rubber composition for clinch, and / or a rubber composition for wings. The pneumatic tire which has a tire member produced using the rubber composition in any one of Claims 1-5.