JP2001348463A - Rubber composition for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire preventing discoloration without spoiling effects of an antioxidant and maintaining the appearances of a tire over a long period of time. SOLUTION: The rubber composition comprises a granulate obtained by mixing an antioxidant with a resin having a softening point or a melting point of at least 80 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire, and more particularly, to a rubber composition for a tire which prevents discoloration without impairing the effect of an antioxidant and maintains the appearance of the tire for a long period of time. .

[0002]

2. Description of the Related Art Conventional pneumatic tires are oxidized and degraded by oxygen and ozone in the air during use for a long period of time, and cracks are generated in groove portions of sidewalls and treads. Cracks not only make the appearance worse,
The rolling of the tire causes cracks to grow and break, which causes a decrease in durability.

[0003] For this reason, in general, various anti-aging agents are blended in a rubber composition for a tire such as a sidewall portion or a tread portion so as to prevent oxidative deterioration. However, in order to obtain sufficient ozone resistance until the end of use of the tire by blending the antioxidant, a relatively large amount of the antioxidant (for example, 4 parts by weight in total with respect to 100 parts by weight of the rubber component). It is necessary to mix the above anti-aging agent). In addition, these anti-aging agents, when subjected to external stimuli such as temperature, strain, and ozone, easily precipitate on the surface, and are further decomposed over time by light such as ultraviolet rays, and this decomposed product causes the tire to become brown or brown. As a result, the appearance of the tire becomes poor and the commercial value of the tire is reduced.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a rubber composition for a tire which prevents discoloration without impairing the effect of an antioxidant and maintains the appearance of the tire for a long period of time. The purpose is to do.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to improve the above-mentioned problems, and as a result, mixed an antioxidant and a resin having a softening point or a melting point of 80 ° C. or more into a rubber composition. By containing the granular material, it is found that discoloration can be prevented without impairing the effect of the antioxidant,
The present invention has been completed.

[0006] That is, the present invention is a rubber composition comprising a particulate material obtained by mixing at least one kind of an antioxidant and a resin having a softening point (or melting point) of 80 ° C or higher. .

In the present invention, the anti-aging agent is a naphthylamine-based antiaging agent, a quinoline-based antiaging agent, a diphenylamine-based antiaging agent, a p-phenylenediamine-based antiaging agent, a hydroquinone derivative antiaging agent, a monophenol-based antiaging agent. Antioxidants, bisphenol antioxidants, trisphenol antioxidants, polyphenol antioxidants, thiobisphenol antioxidants, benzimidazole antioxidants, thiourea antioxidants, phosphorous acid antioxidants And the at least one antioxidant selected from the group consisting of organic thioacid-based antioxidants.

Further, the present invention provides the rubber composition according to claim 1 or 2, wherein the resin is a thermoplastic resin.

[0009] Further, the present invention provides the composition, wherein the resin is polyethylene, polypropylene, polyurethane, polystyrene,
Each of the above rubber compositions being at least one resin selected from the group consisting of acrylic resin, methacrylic resin, ethylene acrylic acid copolymer, vinyl chloride resin, butadiene resin, polybutene resin, polycarbonate, ABS resin and AS resin. It is.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0011] The rubber composition of the present invention contains an antioxidant as a particulate material obtained by mixing with a resin having a softening point or a melting point of 80 ° C or higher, whereby the rubber composition resulting from the antioxidant can be used over time. Discoloration can be prevented.

The antioxidants used in the present invention include:
For example, naphthylamine antioxidants, quinoline antioxidants, diphenylamine antioxidants, p-phenylenediamine antioxidants, hydroquinone derivative antioxidants, monophenol antioxidants, bisphenol antioxidants, trisphenol Antioxidants, polyphenol antioxidants, thiobisphenol antioxidants, benzimidazole antioxidants, thiourea antioxidants, phosphorous acid antioxidants, organic thioacid antioxidants, etc. .

Examples of the naphthylamine-based antioxidants include phenyl-α-naphthylamine, phenyl-β-naphthylamine and aldol-α-trimethyl-1,2-naphthylamine.

As the quinoline anti-aging agent, 2,2,2
4-trimethyl-1,2-dihydroquinoline polymer, 6
-Ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline and the like.

The diphenylamine-based antioxidants include:
p-isopropoxydiphenylamine, p- (p-toluenesulfonylamide) -diphenylamine, N, N-
Examples include diphenylethylenediamine, octylated diphenylamine and the like.

Examples of the p-phenylenediamine-based antioxidants include N-isopropyl-N'-phenyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, and 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-phenylenediamine,
N- (1,3-dimethylbutyl) -N′-phenyl-p
-Phenylenediamine, N, N'-diaryl-p-phenylenediamine, hindered diaryl-p-phenylenediamine, phenyl, hexyl-p-phenylenediamine, phenyl, octyl-p-phenylenediamine and the like.

The hydroquinone derivative antioxidants include:
2,5-di- (tert-amyl) hydroquinone, 2,
5-di-tert-butylhydroquinone and the like.

The monophenolic antioxidants include:
2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butylphenol, 1-
Oxy-3-methyl-4-isopropylbenzene, butylhydroxyanisole, 2,4-dimethyl-6-te
rt-butylphenol, n-octadecyl-3-
(4'-hydroxy-3 ', 5'-di-tert-butylphenyl) propionate, styrenated phenol and the like.

As the bisphenol-based antiaging agent, trisphenol-based antiaging agent or polyphenol-based antiaging agent, 2,2'-methylene-bis- (4-methyl-
6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-butylidene-bis- (3-methyl-
6-tert-butylphenol), 1,1'-bis-
(4-hydroxyphenyl) -cyclohexane, tetrakis- [methylene-3- (3 ′, 5′-di-tert-)
Butyl-4'-hydroxyphenyl) propionate]
Examples include methane.

The thiobisphenol-based antioxidants include 4,4'-thiobis- (6-tert-butyl-3).
-Methylphenol), 2,2'-thiobis- (6-t
tert-butyl-4-methylphenol) and the like.

Examples of the benzimidazole antioxidant include 2-mercaptomethylbenzimidazole and the like.

Examples of the thiourea antiaging agent include tributylthiourea.

Examples of the phosphorous acid antioxidant include tris (nonylphenyl) phosphite.

The organic thioacid-based antioxidants include dilauryl thiodipropionate.

These antioxidants can be used alone or in combination of two or more.

The temperature at which the granular material is broken by melting or softening, that is, the softening point or melting point of the resin is 80 ° C.
Above, preferably 80 to 200 ° C, more preferably 9 ° C
The temperature is 0 to 180 ° C, more preferably 100 to 170 ° C. If the temperature at which the resin melts or softens is less than 80 ° C,
In the process before vulcanization, the resin is destroyed by melting or softening, etc., so that the desired effect of preventing discoloration cannot be obtained. Is not preferable because the effect of (1) cannot be obtained.

The resin used in the present invention can maintain the granular structure of the granular material without melting or breaking at a temperature below the vulcanization temperature, and melt or soften at a temperature above the vulcanization temperature, resulting in deterioration of physical properties. Breakable resins are preferred, and thermoplastic resins are preferred.

Examples of such a thermoplastic resin include polyurethane, polystyrene, acrylic resin, methacrylic resin, ethylene acrylic acid copolymer (EEA),
Preferred are ethylene-vinyl acetate copolymer (EVA), vinyl chloride resin, butadiene resin, butene resin, ABS resin, AS resin, polycarbonate, polyethylene, and polypropylene. Among them, polyurethane, methacrylic resin and polystyrene are preferably used.

The mixing ratio (weight ratio) of the antioxidant and the resin is as follows:
The resin can be used in an amount of 0.5 to 10, preferably 1 to 8, for the antioxidant 1. If the mixing ratio of the resin is less than 0.5 with respect to the antioxidant 1, it is not preferable because the adsorption with the antioxidant is not sufficient. If it exceeds 10, the resin may adversely affect the physical properties of the rubber composition. It is not preferable because there is.

The average particle size of the granular material of the present invention is 120 μm.
m or less, more preferably 10 to 100 μm. When the average particle diameter of the granular material is larger than 120 μm,
Although the adsorption force between the resin and the antioxidant is large, the effect of preventing discoloration can be sufficiently exhibited, but the effect as an antioxidant decreases, which is not preferable. Conversely, the average particle size of the granular material is 10 μm
If it is smaller, the resin is likely to melt or soften, and a sufficient discoloration preventing effect cannot be obtained, which is not preferable.

As the method for producing the granular material used in the present invention, a method of mixing an antioxidant and a resin with an internal mixer or an extruder and freeze-grinding the mixture, or a chemical or physical chemical method And the like. In addition to these, a spray drying method or the like may be used.

[0032] The rubber composition of the present invention contains at least one rubber component.

The rubber component used in the present invention can be natural rubber (NR) and / or a diene-based synthetic rubber. As the diene rubber used in the present invention,
Examples include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. One or more rubber components may be contained in the rubber component used in the present invention.

The compounding amount of the above-mentioned granular material is the same as that of the above-mentioned rubber component 10
With respect to 0 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, still more preferably 0.5 to 5 parts by weight.
3 parts by weight. If the amount of the granular material is less than 0.5 part by weight, a sufficient effect of preventing discoloration cannot be obtained. If the amount exceeds 5 parts by weight, the amount of the antioxidant increases, which is not preferable in appearance.

Next, the rubber composition of the present invention can contain carbon black as a filler. The compounding amount of carbon black contained in the rubber composition of the present invention is preferably 10 to 150 parts by weight based on 100 parts by weight of the rubber component. If the compounding amount of carbon black is less than 10 parts by weight, a sufficient reinforcing effect cannot be obtained, and if it exceeds 150 parts by weight, low heat buildup tends to increase. 15 to 100 parts by weight, more preferably 25 to 100 parts by weight from the viewpoint of reinforcing properties and low heat generation
80 parts by weight are preferred.

Examples of carbon black that can be used in the present invention include, but are not limited to, HAF, ISAF, SAF, and the like.

[0037] The rubber composition of the present invention may contain a white filler such as silica. Specific examples of the white filler include silica, clay, alumina, takul, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, titanium oxide, and the like. A mixture of more than one species can be used. Particularly preferred white fillers are silica, clay, aluminum hydroxide and alumina.

The upper limit of the compounding amount of the white filler is as follows.
The amount can be 100 parts by weight, preferably 85 parts by weight, more preferably 65 parts by weight based on 00 parts by weight.
The lower limit can be 5 parts by weight. When the amount of the white filler is less than 5 parts by weight, the reinforcing effect is small,
Exceeding 0 parts by weight is not preferred because workability decreases. From the viewpoint of low heat generation and workability, the amount of the white filler is preferably 65 parts by weight or less.

When a white filler is used, a coupling agent, especially a silane coupling agent, may be used to strengthen the bond between the filler and the rubber component and improve the wear resistance of the rubber composition. . The amount of the silane coupling agent is preferably from 1 to 20% by weight based on the weight of the white filler from the viewpoint of the dispersing effect and the coupling effect.

In addition to the rubber component, carbon black, white filler, coupling agent and particulate matter, the rubber composition of the present invention may further comprise, if necessary, a softener, an antioxidant, a vulcanizing agent, Compounding agents used in the ordinary rubber industry, such as vulcanization accelerators, vulcanization accelerators, waxes, stearic acid, and zinc oxide, can be appropriately compounded.

In the rubber composition of the present invention, the rubber component, carbon black, white filler, coupling agent, granular material and compounding agent are kneaded by a usual processing device, for example, a roll, a Banbury mixer, a kneader or the like. Can be obtained.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but this does not limit the purpose of the present invention.

Examples 1-4 and Comparative Example 1 (Explanation of Various Chemicals) Antioxidant 6C: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (chemical name: N-methyl-N '-(1,3 -Dimethylbutyl) -p-phenylenediamine) Polystyrene: manufactured by Kishida Chemical (softening point: 98 ° C.) Polymethyl methacrylate: manufactured by Wako Pure Chemical Industries, Ltd. (softening point: 1)
10 ° C.) Polyurethane: Milactran P-26M manufactured by Nippon Milactran Co., Ltd. (softening point: 123 ° C.) Carbon black: Show Black N220 manufactured by Showa Cabot Co., Ltd. Stearic acid: Stearic acid manufactured by NOF CORPORATION Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: Noxeller C manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Z (chemical name: N-cyclohexyl-2-benzothiazylylsulfenamide)

(Preparation of Granules) The antioxidant 6C and the resin shown in Table 1 were mixed in a 60 cc lab blast mill according to the mixing ratio shown in Table 1. After the mixture was freeze-pulverized, granules (samples 1 to 3) were obtained. Table 1 shows the average particle size of the granular material.

[0045]

[Table 1]

(Preparation of Rubber Plate) The formulation is shown in Table 2.
Samples 1-3 obtained as described above and the compounding ingredients other than the vulcanizing agent were kneaded with a Banbury mixer to prepare a master batch, and then the master batch, the vulcanizing agent, and samples 1 to 8 were rolled on an 8-inch roll. No. 3 was prepared by kneading. These compounds were press-vulcanized at 170 ° C. for 20 minutes to obtain vulcanized products, and the physical properties were evaluated.

[0047]

[Table 2]

(Evaluation Method) (1) Discoloration of Appearance Using a vulcanized rubber plate having a thickness of 4 mm, these test pieces were exposed outdoors without rainwater. After exposure for 30 days, the appearance was visually observed, and the degree of discoloration was evaluated on a five-point scale. The smaller the value, the greater the degree of discoloration.

(2) Ozone resistance The test pieces left at 24 ° C. for 48 hours after vulcanization and the test pieces exposed outdoors for 30 days according to the method described above were subjected to JIS.
It was evaluated in accordance with K6259. That is, an ozone concentration of 50 ± 5 pphm and a tensile amount of 20 ± 2% are set to 9
After continuously exposing the test piece for 6 hours, the test piece was taken out of the test tank, and the state of cracks was observed with respect to the number of cracks and the size and depth of the cracks under the following conditions.

Regarding the number of cracks, a small number of cracks was evaluated as A, a large number of cracks as B, and an infinite number of cracks as C. Regarding the size and depth of the crack, 1 is not visible to the naked eye but can be confirmed with a magnifying glass of 10 times, 2 is visible to the naked eye, 2 is deep crack and relatively large (less than 1 mm) is 3. Large and deep cracks (1m
m or more and less than 3 mm) was evaluated as 4, and a material likely to cause a crack or cut of 3 or more mm was evaluated as 5.

(Evaluation Results) The results are shown in Table 3.

[0052]

[Table 3]

In comparison with Comparative Example 1 in which the antioxidant 6C was blended by the conventional method, Examples 1 to 5 in which the antioxidant 6C was blended as a granular material comprising a mixture of polystyrene, polymethyl methacrylate or polyurethane resin were used. In 4,
Discoloration due to outdoor exposure was small, and ozone resistance after outdoor exposure was improved.

[0054]

According to the present invention, it is possible to provide a rubber composition for a tire which prevents discoloration without impairing the effect of the anti-aging agent and maintains the appearance of the tire for a long period of time.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 5, 2000 (2007.5.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

[0037] The rubber composition of the present invention may contain a white filler such as silica. As specifically the white filler, silica, clay, alumina, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, and titanium oxide and the like, they are alone or Two or more kinds can be used as a mixture. Particularly preferred white fillers are silica, clay, aluminum hydroxide and alumina.

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 4J002 AC01W AC03W AC06W AC07W AC08W AC09W BB03X BB06X BB07X BB12X BB15W BB17X BB18X BC03X BC06X BD04X BG04X BG05X BG06X BL01X BN15X EV00 076 EB00 076

Claims (4)

[Claims] 1. An antioxidant and a softening point or melting point of 80 ° C.
A rubber composition comprising a particulate material obtained by mixing the above resin. 2. The anti-aging agent is a naphthyl amine-based anti-aging agent, a quinoline-based anti-aging agent, a diphenylamine-based anti-aging agent, a p-phenylenediamine-based anti-aging agent, a hydroquinone derivative anti-aging agent, a monophenol-based anti-aging agent, Bisphenol antioxidants, trisphenol antioxidants, polyphenol antioxidants, thiobisphenol antioxidants, benzimidazole antioxidants, thiourea antioxidants, phosphorous acid antioxidants and organic thioacids The rubber composition according to claim 1, wherein the rubber composition is at least one antioxidant selected from the group consisting of a system antioxidant. 3. The method according to claim 1, wherein said resin is a thermoplastic resin.
Or the rubber composition according to 2. 4. The resin is made of polyethylene, polypropylene, polyurethane, polystyrene, allyl resin, methacrylic resin, ethylene acrylic acid copolymer, ethylene vinyl acetate copolymer, vinyl chloride resin, butadiene resin, butene resin, polycarbonate, ABS. 3. The rubber composition according to claim 1, which is at least one resin selected from the group consisting of a resin and an AS resin.