JP2003313365A - Rubber composition for carcass ply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a carcass ply which gives a carcass ply rubber excellent in the balance between fluidity and strength and can improve the durability of a pneumatic tire. <P>SOLUTION: This rubber composition is used as a carcass ply rubber formed around a ply cord of a carcass of a pneumatic tire and is prepared by incorporating 2-15 pts.mass rubber powder into 100 pts.mass rubber component comprising a natural rubber and/or a synthetic diene rubber. The rubber powder has an average particle size of 0.3 mm or less and a maximum particle size of 0.6 mm or less; in the particle size distribution of the rubber powder, rubber particles with particle sizes of 0.5 mm or lower preferably occupy at least 95% of the total rubber particles. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carcass ply rubber composition used as a carcass ply rubber for a pneumatic tire.

[0002]

2. Description of the Related Art Generally, the carcass part of a pneumatic tire is
It is composed of one or a plurality of carcass plies in which carcass ply rubber is coated around ply cords arranged in a woven fabric shape or arranged in parallel. This pneumatic tire is manufactured by molding an inner liner rubber adjacent to the inner film side of the tire of the carcass ply, and then vulcanizing.

However, at the time of this vulcanization, the carcass ply and the inner liner rubber are pressed by the plader in the mold toward the outside of the tire outer diameter, but the ply cords in the carcass ply are relatively compressed. Due to the high tensile strength and the high fluidity of the carcass ply rubber, the phenomenon that the inner liner rubber flows between the ply cords occurs. As a result, the carcass ply is divided by the inner liner rubber having low strength on the way, which causes the durability of the pneumatic tire to be reduced.

[0004]

In view of the above circumstances, the present invention provides a carcass ply rubber composition which has an excellent balance between fluidity and strength of the carcass ply rubber and which can improve the durability of a pneumatic tire. The purpose is to provide.

[0005]

The present invention relates to a rubber composition used as a carcass ply rubber formed around a ply cord in a carcass portion of a pneumatic tire, which is a natural rubber and / or a diene synthetic rubber. The rubber composition for a carcass ply contains 2 to 15 parts by mass of powder rubber based on 100 parts by mass of the rubber component.

In the rubber composition for carcass ply of the present invention, the powder rubber has an average particle diameter of 0.3 mm.
It is preferable that the particle size distribution of the powder rubber having the following values, the maximum particle size of 0.6 mm or less, and the particle size of 0.5 mm or less is 95% or more of the entire powder rubber.

Further, in the rubber composition for carcass ply of the present invention, a solidification inhibitor having a mass of 2 to 12 wt% (mass%) of the powder rubber adheres to the surface of the powder rubber. preferable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(Rubber Component) In the rubber composition for carcass ply of the present invention, a rubber component composed of natural rubber (NR) and / or diene synthetic rubber is used. Here, the diene-based synthetic rubber is not particularly limited, and conventionally known ones can be used. For example, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), ethylene-propylene. -Diene rubber (EPDM), chloroprene rubber (CR) or acrylonitrile-butadiene rubber (NBR) etc. can be used. Further, these diene synthetic rubbers may be used alone or in combination of two or more kinds. Above all, it is preferable to use natural rubber (NR) and / or styrene-butadiene rubber (SBR) for the rubber composition for carcass ply of the present invention. In this case, the strength and heat resistance of the carcass ply rubber can be further improved.

When the rubber composition for carcass ply of the present invention is used by mixing natural rubber (NR) and diene synthetic rubber, the mixing ratio of natural rubber (NR) and diene synthetic rubber is The mass ratio is preferably 40:60 to 80:20. In this case, the strength and heat resistance of the carcass ply rubber can be further improved.

(Powder rubber) The rubber composition for carcass ply of the present invention contains 2 to 15 parts by mass of powder rubber based on 100 parts by mass of the rubber component. Powder rubber content is 2
If the amount is less than 10 parts by mass, the effect of reducing the fluidity of the carcass ply rubber cannot be sufficiently obtained, and 15
If it exceeds the mass part, the strength of the carcass ply rubber will be reduced.

Here, the powder rubber is more preferably contained in an amount of 3 to 10 parts by mass with respect to 100 parts by mass of the rubber component. In this case, the balance between the fluidity and the strength of the carcass ply rubber can be made more excellent.

The powdered rubber has an average particle size of 0.3 mm or less, a maximum particle size of 0.6 mm or less, and a particle size distribution of powdered rubber of 0.5 mm or less. It is preferably 95% or more of the entire rubber.
More preferably, the average particle size is 0.25 mm or less, the maximum particle size is 0.5 mm or less, and 0.
The particle size distribution of powder rubber having a particle size of 5 mm or less is 95% or more of the entire powder rubber. Average particle size of rubber powder,
When the maximum particle size and particle size distribution satisfy the above requirements, the strength of the carcass ply rubber can be further improved.

Further, the material of the powdered rubber is not particularly limited, and conventionally known rubber components and the like can be used. For example, the rubber portion of a used waste tire from which steel cords and fibers have been removed. It is preferable to use recycled rubber obtained by recycling the above. In this case, not only the production cost of the pneumatic tire can be reduced, but it can also contribute to resource saving and environmental protection.

On the surface of the powder rubber, 2 to
It is preferable that the solidification inhibitor has a mass of 12 wt%. When the mass of the powder rubber is less than 2 wt% of the solidification inhibitor, the powder rubber solidifies to impair its fluidity, resulting in poor handling performance and poor productivity. There is a tendency. Further, when a solidification inhibitor having a mass of more than 12 wt% of the powder rubber is attached, the physical properties of the powder rubber are greatly affected by the solidification inhibitor, and thus the rubber physical properties such as rubber hardness are increased. The impact on them tends to increase. further,
The balance between fluidity and strength of the carcass ply rubber tends to be affected. The average particle size of the powder rubber is 0.3 mm or less, the maximum particle size is 0.6 mm or less, and the particle size distribution of the powder rubber having a particle size of 0.5 mm or less is 95% or more of the entire powder rubber. In some cases, these tendencies become particularly large.

Further, the surface of the powdered rubber has 4-1 of the powdered rubber.
It is more preferable that the solidification inhibitor has a mass of 0 wt%. In this case, an excellent powder rubber can be obtained due to the balance between the effect on the powder rubber and the carcass ply rubber and the handling performance.

Here, the anti-caking agent refers to one having a function of suppressing the caking of the powder rubbers with each other and imparting fluidity to the powder rubbers. Examples of the material thereof include talc and silica. , Calcium carbonate, hard clay or zinc oxide.

As a method for adhering the above-mentioned anti-caking agent, a conventionally known method is used. For example, after crushing a rubber portion of a used waste tire with a crusher such as a roll crusher,
There is a method of mixing the above-mentioned caking inhibitor.

(Additive) Further, the rubber composition for carcass ply and the powdered rubber of the present invention may further contain additives such as a vulcanizing agent, a vulcanization accelerator, a softening agent, a lubricant, an antioxidant and a filler. It can be blended. As the vulcanizing agent, for example, sulfur, a peroxide cross-linking agent or the like can be used. Examples of the peroxide crosslinking agent include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, and 2,5-dimethyl-2,5. -Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane and the like can be used.
As the vulcanization accelerator, for example, sulfenamide-based, thiazole-based, thiuram-based, dithioacid-based, thiourea-based, guanidine-based or dithiocarbamic acid-based vulcanization accelerators can be used.

Examples of the softening agent include dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate and diisodecyl phthalate. , Di-n-decyl phthalate, di-n-dodecyl phthalate, diisotridecyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, di-2 adipate
-Ethylhexyl, di-n-decyl adipate, diisodecyl adipate, tributyl phosphate, tri-2 phosphate
-Ethylhexyl, 2-ethylhexyl phosphate, tricresyl phosphate, butyl stearate, butyl oleate, process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petrolatum, castor oil, linseed oil, rapeseed oil or coconut oil Can be done.

Examples of the lubricant include hydrocarbons such as liquid paraffin, natural paraffin, micro wax and polyethylene wax, stearic acid, barium stearate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate and the like. Fatty acid amide type lubricants such as fatty acid type, stearic acid amide, palmitic acid amide, methylene bis stearoamide, ethylene bis stearoamide and the like can be used. As the antiaging agent, amine-based, phenol-based, imidazole-based antiaging agents, carbamic acid metal salts, waxes and the like can be used. Examples of the filler include zinc oxide, carbon black, white carbon, calcium carbonate, magnesium carbonate, clay,
There are talc, mica, alumina, barium sulfate, calcium sulfate and the like.

(Manufacturing Method) As a method for manufacturing the rubber composition for carcass ply of the present invention, a conventionally known method can be used. For example, the above rubber component, powdered rubber, additives and the like can be used in a roll, a Banbury mixer or the like. There is a method of kneading with a mixer. By molding and vulcanizing the rubber composition for a carcass ply of the present invention thus obtained as a carcass ply rubber, a pneumatic tire having excellent durability can be produced.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Preparation of sample) i) Preparation of powdered rubber to which talc is adhered After crushing the rubber portion of a used waste tire with a pulverizer such as roll pulverizer, talc is added to obtain the specifications shown in Table 1. Powder rubbers A to F having talc attached thereto were prepared. The adhesion amount of talc in Table 1 is based on mass% with respect to powder rubber.

[0025]

[Table 1]

(Note 1) "T-" manufactured by Fuji Talc Industry Co., Ltd.
2 ”. ii) Preparation of Vulcanized Rubbers of Examples and Comparative Examples A rubber material was weighed so as to have a composition shown in Table 2 below, and the above-described powder rubber A to which talc was attached so as to have a composition shown in Table 3 below. F was weighed. Then, a rubber composition obtained by kneading these with a Banbury mixer was press-vulcanized at 170 ° C. for 15 minutes to obtain Example 1.
7 and vulcanized rubbers of Comparative Examples 1 and 2 were obtained. Table 2
And the blending amount of each component in Table 3 is based on parts by mass.

[0027]

[Table 2]

(Note 2) "RSS # 3" made in Thailand. (Note 3) “Sumitomo SBR1502” manufactured by Sumitomo Chemical Co., Ltd. (Note 4) "Dia Black H" manufactured by Mitsubishi Chemical Corporation. (Note 5) "Diana Process PA3" manufactured by Idemitsu Kosan Co., Ltd.
2 ”. (Note 6) "Nocrac 6" manufactured by Ouchi Shinko Chemical Co., Ltd.
C ". (Note 7) "Stearic acid camellia" manufactured by NOF Corporation. (Note 8) "Zinc oxide type 2" manufactured by Mitsui Metal Industry Co., Ltd. (Note 9) "Seimi Sulfur" manufactured by Nippon Kyokuto Co., Ltd. (Note 10) "Nox Cellar N" manufactured by Ouchi Shinko Chemical Co., Ltd.
S ".

Iii) Preparation of Small Tires of Examples and Comparative Examples A rubber composition having the composition shown in Table 3 below was topped on a ply cord, and an inner liner rubber having the composition shown in Table 2 was applied to the inner film side of the tire. It was attached and a green tire was molded. Then, this green tire was placed in a vulcanization mold and vulcanized in the mold at 175 ° C. for 15 minutes,
Examples 1 to 7 of 195 / 65R15 and Comparative Example 1 so that the number of ply cords to be driven becomes 50/50 mm.
~ 2 small tires were produced. At this time, the internal pressure of the plader was set to 20 kg / cm ² .

(Evaluation Method) i) Strength of Vulcanized Rubber The strength of the vulcanized rubber of Examples 1 to 7 and Comparative Examples 1 and 2 was evaluated by measuring the tensile strength and the tear strength. The evaluation results are shown in Table 3. The tensile strength was measured according to JIS K6251 and the tear strength was measured according to JIS K6252. The values of tensile strength and tear strength in Table 3 are relative values when Comparative Example 1 is set to 100.

Ii) Fluidity of Carcass Ply Rubber The fluidity of the carcass ply rubber was evaluated by cutting the small tires of Examples 1 to 7 and Comparative Examples 1 to 2 in the direction perpendicular to the tire rotation direction, and The measurement was performed by measuring the distances L and L1 between the inner liner rubber 4 and the ply cord 2 as shown in FIG. The results are shown in Table 3. In addition, L and L1 shown in FIGS. 1 and 2 are the inner liner rubber 4-ply cord 2 before vulcanization of the tire.
Is the distance between. Further, the larger the value of L1 with respect to the value of L in Table 3, the smaller the fluidity.

Iii) Solidified state of powdered rubber The solidified state of the powdered rubbers A to F to which talc was adhered was evaluated by filling the flexible container with 500 kg of the powdered rubber and leaving it for one month, and then evaluated according to the following criteria. . The evaluation results are shown in Table 3. ◎ ... Not solidified at all ○ ... Mostly not solidified △ ... Mostly solidified

[0033]

[Table 3]

(Evaluation Results) The samples of Examples 1 to 7 were more excellent in balance between strength and fluidity of the vulcanized rubber than the samples of Comparative Examples 1 and 2. Further, the samples of Examples 1 to 3 tended to be relatively excellent in strength as compared with the samples of Examples 4 to 5 and 7. The samples of Examples 1 to 3 are the same as Example 6.
In comparison with the sample No. 2, the powder rubber tended to be relatively excellent in the solidified state.

The embodiments and examples disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0036]

As described above, according to the present invention, it is possible to suppress the fluidity of the carcass ply rubber at the time of manufacturing the pneumatic tire and to obtain the carcass ply rubber having excellent strength, so that the durability of the pneumatic tire is improved. The sex can be improved. Further, when using a powdered rubber obtained by crushing a waste tire for the powdered rubber contained in the rubber composition of the present invention, not only the production cost of the pneumatic tire can be reduced, but also resource saving and environmental protection can be achieved. The purpose of can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an interface between a carcass ply rubber and an inner liner rubber before vulcanization of a tire.

FIG. 2 is a schematic cross-sectional view showing an example of an interface between a carcass ply rubber and an inner liner rubber after vulcanization of a tire.

[Explanation of symbols]

1 carcass ply, 2 ply cord, 3 carcass ply rubber, 4 inner liner rubber.

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Claims (3)

[Claims] 1. A rubber composition used as a carcass ply rubber formed around a ply cord in a carcass part of a pneumatic tire, wherein 100 parts by mass of a rubber component composed of natural rubber and / or diene synthetic rubber is used. On the other hand, a rubber composition for a carcass ply containing 2 to 15 parts by mass of powdered rubber. 2. The average particle size of the powder rubber is 0.3 mm or less, the maximum particle size is 0.6 mm or less, and the particle size distribution of the powder rubber having a particle size of 0.5 mm or less is the whole powder rubber. 95% or more of the rubber composition for carcass plies according to claim 1. 3. The rubber composition for a carcass ply according to claim 1, wherein a solidification inhibitor having a mass of 2 to 12 wt% of the powder rubber is attached to the surface of the powder rubber. object.