JP2010209176A - Rubber composition for covering organic fiber material and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for covering an organic fiber material, which improves a vulcanization rate and fatigue resistance without impairing processability and a pneumatic tire having an organic fiber reinforcing layer obtained by covering an organic fiber material with the rubber composition. <P>SOLUTION: The rubber composition for covering an organic fiber material comprises ≥0.5 pt.wt. and ≤10 pts.wt. of an alkyl group modified saccharide derivative represented by general formula (1) and ≥0.1 pt.wt. and ≤2.0 pts.wt. of a vulcanization accelerator based on 100 pts.wt. of diene-based rubber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition for coating an organic fiber material, and a pneumatic tire using the rubber composition.

  Conventionally, for example, in a pneumatic tire, an organic fiber reinforcing layer formed by coating an organic fiber material such as nylon or polyester with a rubber composition is provided as a carcass or a chafer.

  For example, Patent Document 1 below discloses a tire including a carcass layer formed by coating a carcass cord made of an organic fiber such as polyester with a rubber composition. As the rubber composition, sulfur, benzothia At least one primary vulcanization accelerator selected from disulfenamides and mercaptobenzothiazole, and at least one secondary vulcanization accelerator obtained from zinc dibenzyldithiocarbamate and tetrabenzylthiuram disulfide; Is disclosed.

  Patent Document 2 listed below discloses a tire in which a chafer formed by coating an organic fiber fabric with a rubber composition is provided outside a carcass winding portion in a bead portion. As the rubber composition, butadiene is used. It is disclosed that silica, resorcin or a derivative thereof, and a hexamethylenetetramine or a melamine derivative are blended with a rubber component including rubber.

  In the following Patent Document 3, as the chafer rubber, diene rubber, sulfenamide-based first vulcanization accelerator, tetrabenzylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, and zinc disulfide are used. It is disclosed that at least one second vulcanization accelerator selected from the group consisting of benzyldithiocarbamate, resorcin or a derivative thereof, and a methylene donor are blended.

  Although the durability of the tire could be improved by these techniques, there is a demand for further extending the life of the tire, and an improvement in fatigue resistance is also required in the rubber composition for coating an organic fiber material. .

  By the way, the technique of adding saccharides, such as starch, to a rubber composition is conventionally known. For example, Patent Document 4 below proposes blending monosaccharides such as D-fructose and D-glucose, sugar alcohols, polysaccharides and the like into diene rubbers in order to improve adhesion with steel cords. ing.

  In Patent Document 5 below, in order to improve adhesion aging resistance without impairing fracture characteristics, wet grip properties, exothermic property and workability, the rubber composition for organic fiber reinforcing layer may contain monosaccharides or more than disaccharides. It is disclosed that saccharides such as sugar alcohols, deoxy sugars, amino sugars, glycosides, uronic acids, sugar fatty acid esters and the like are blended.

  Patent Document 6 below proposes blending a complex of a diene rubber and a saccharide such as starch in order to improve wet grip properties and low fuel consumption without impairing wear resistance.

  Thus, it has been conventionally known that a saccharide is added to a rubber composition, but it has not been proposed to add an alkyl group-modified sugar derivative unique to the present invention, and this is an advantageous effect. The effect of improving fatigue resistance has not been known.

Japanese Patent Laid-Open No. 11-049897 JP-A-11-263102 JP 2008-069207 A JP 07-118457 A Japanese Patent Laid-Open No. 11-071481 JP 2005-272507 A

  This invention is made | formed in view of the above point, and it aims at providing the rubber composition for organic fiber material coating | cover which can improve fatigue resistance, without impairing workability.

  The rubber composition for coating an organic fiber material according to the present invention comprises 0.5 parts by weight or more and 10 parts by weight of an alkyl group-modified sugar derivative obtained by reacting a primary alcohol with glucose with respect to 100 parts by weight of a diene rubber. The vulcanization accelerator is contained in an amount of 0.1 parts by weight or more and 2.0 parts by weight or less, and the vulcanization accelerator comprises a dithiocarbamate vulcanization accelerator and a thiuram vulcanization accelerator. At least one selected from the group consisting of 0.1 parts by weight and 0.5 parts by weight.

  The pneumatic tire according to the present invention includes an organic fiber reinforcing layer formed by coating an organic fiber material with such a rubber composition.

  According to the present invention, by incorporating the alkyl group-modified sugar derivative together with the specific vulcanization accelerator, fatigue resistance can be improved without impairing workability, and the vulcanization rate can be increased. Can be improved. Therefore, not only can it contribute to extending the life of the tire, but also productivity can be improved.

It is a half sectional view showing an example of a heavy duty pneumatic tire.

1 ... bead part, 2 ... bead core, 3 ... carcass,
4 ... carcass hoisting part, 5 ... chafer

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The rubber composition of the present invention contains a diene rubber as a rubber component. The diene rubber is not particularly limited. For example, natural rubber (NR), epoxidized natural rubber (ENR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), polyisoprene rubber (IR), ethylene propylene diene. Examples thereof include rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and butyl rubber (IIR). These diene rubbers may be used alone or in combination of two or more. Among these, it is preferably at least one selected from the group consisting of NR, IR, SBR and BR. Furthermore, NR and / or IR alone or NR and / or IR is 60% by weight or more. , SBR and / or BR is preferably a blend rubber having 40% by weight or less.

  The alkyl group-modified sugar derivative blended in the rubber composition of the present invention is obtained by reacting glucose with a primary alcohol. As glucose, D-glucose or L-glucose may be used, but natural glucose, that is, D-glucose is preferably used. Moreover, as a primary alcohol, it is preferable to use a C1-C25 saturated alcohol.

  Therefore, as the alkyl group-modified sugar derivative, it is preferable to use alkyl-D-glucopyranoside whose alkyl group has 1 to 25 carbon atoms. Using such an alkyl group-modified sugar derivative derived from natural glucose also leads to a reduction in petroleum resource-derived raw materials. In this case, the glucopyranoside may be α-type (that is, alkyl-α-D-glucopyranoside), β-type (that is, alkyl-β-D-glucopyranoside), or a mixture of both. Here, as the alkyl group, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, neohexyl group , Heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl Group, tetracosyl group and pentacosyl group.

As the alkyl group-modified sugar derivative, alkyl-α-D-glucopyranoside represented by the following general formula (1) is particularly preferably used.

  In said formula, n is an integer of 0-24. When the carbon number of the alkyl group represented by (n + 1) is too large, the contribution of the glucose moiety becomes small and the effect of addition tends to approach that of paraffin oil, so it is preferably 25 or less. n is more preferably an integer of 0 to 12, and still more preferably an integer of 2 to 10.

Alkyl-D-glucopyranoside is obtained by reacting glucose with a primary alcohol as shown in the following formula (2). In this reaction, for example, glucose and a primary alcohol are heated and reacted in the presence of hydrochloric acid and a cation exchange resin (see Japanese Patent Publication No. 50-13770), and a cation exchange resin (a mixture of styrene and divinylbenzene as a catalyst). A method in which glucose and a primary alcohol are reacted using a three-dimensional polymer substrate produced by condensation with a sulfonic acid group bonded as an exchange group as a fixed bed (see JP-A-6-92984), A method of reacting glucose and primary alcohol using transglucosidase (α-glucosidase) as a catalyst (see JP-A-7-87992), and converting glucose and primary alcohol into clay minerals (montmorillonite, beidellite, saponite, A method of reacting in the presence of hectorite (Japanese Patent Laid-Open No. 10-204095) Broadcast reference) can be carried out by such.

  The compounding amount of the alkyl group-modified sugar derivative is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the diene rubber. If the blending amount is less than 0.5 parts by weight, the effect of addition is insufficient. Conversely, if it exceeds 10 parts by weight, the workability deteriorates. The lower limit of the amount of the alkyl group-modified sugar derivative is more preferably 1 part by weight or more, and the upper limit is more preferably 5 parts by weight or less.

  In the rubber composition of the present invention, the vulcanization accelerator is blended at 0.1 to 2.0 parts by weight with respect to 100 parts by weight of the diene rubber. When the blending amount of the vulcanization accelerator exceeds 2.0 parts by weight, the scorch resistance deteriorates and the workability deteriorates, and the fatigue resistance also deteriorates. The blending amount of the vulcanization accelerator is more preferably 0.5 to 1.8 parts by weight, and still more preferably 0.8 to 1.5 parts by weight.

  In the rubber composition of the present invention, 0.1 to 0.5 weight of at least one selected from the group consisting of a dithiocarbamate vulcanization accelerator and a thiuram vulcanization accelerator is used as the vulcanization accelerator. It is preferable to blend partly. If the blending amount is less than 0.1 parts by weight, the effect of addition is insufficient, and if it exceeds 0.5 parts by weight, the scorch resistance deteriorates and the workability deteriorates, and the fatigue resistance also deteriorates. This amount is more preferably 0.1 to 0.3 parts by weight.

  Examples of the dithiocarbamate vulcanization accelerator include zinc dibenzyldithiocarbamate (ZnBzDTC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), and zinc di-n-butyldithiocarbamate (ZnBDC). , Zinc N-pentamethylenedithiocarbamate (ZnPDC), zinc ethylphenyldithiocarbamate (ZnEPDC), sodium dimethyldithiocarbamate (NaMDC), sodium diethyldithiocarbamate (NaEDC), sodium di-n-butyldithiocarbamate (NaBDC), diethyl Examples include tellurium dithiocarbamate (TeEDC), copper dimethyldithiocarbamate (CuMDC), and iron dimethyldithiocarbamate (FeMDC). It is. These may be used alone or in combination of two or more. Among these, it is particularly preferable to use zinc dibenzyldithiocarbamate as the dithiocarbamate vulcanization accelerator.

  Examples of the thiuram vulcanization accelerator include tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT), and the like. These may be used alone or in combination of two or more. May be. TBzTD and TOT are particularly suitable as thiuram vulcanization accelerators because they have a bulky hydrocarbon group (benzyl group, 2-ethylhexyl group) as an amino group substituent, and therefore can suppress initial reactivity. is there.

  In the rubber composition of the present invention, as the vulcanization accelerator, it is preferable to use a sulfenamide vulcanization accelerator together with the dithiocarbamate vulcanization accelerator and / or the thiuram vulcanization accelerator. . By using a sulfenamide vulcanization accelerator in combination, the effect of the present invention can be further enhanced. The blending amount of the sulfenamide vulcanization accelerator is preferably 0.7 to 1.5 parts by weight with respect to 100 parts by weight of the diene rubber.

  Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (BBS), N- Oxydiethylene-2-benzothiazolylsulfenamide (OBS), N, N-diisopropyl-2-benzothiazolylsulfenamide (DPBS), N, N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS) These may be used, and these may be used alone or in combination of two or more.

  A methylene acceptor and a methylene donor can be blended with the rubber composition of the present invention. The adhesiveness between the rubber and the organic fiber material can be enhanced by the curing reaction between the hydroxyl group of the methylene acceptor and the methylene group of the methylene donor.

  As the methylene acceptor, a phenolic compound or a phenolic resin obtained by condensing a phenolic compound with formaldehyde is used. Examples of the phenol compounds include phenol, resorcin, and alkyl derivatives thereof. Alkyl derivatives include derivatives of relatively long-chain alkyl groups such as nonylphenol and octylphenol, as well as methyl group derivatives such as cresol and xylenol. The phenol compound may contain an acyl group such as an acetyl group as a substituent.

  In addition, phenolic resins obtained by condensing phenolic compounds with formaldehyde include resorcin-formaldehyde resins, phenolic resins (that is, phenol-formaldehyde resins), cresol resins (that is, cresol-formaldehyde resins), and a plurality of phenols. Formaldehyde resins made of compounds are included. These are uncured resins that have liquid or heat fluidity.

  Among these, from the viewpoint of compatibility with the rubber component and other components, the denseness of the resin after curing, and the reliability, the methylene acceptor is preferably resorcin or a resorcin derivative, and in particular, resorcin or resorcin-alkylphenol. -Formalin resin is preferably used.

  As the methylene donor, hexamethylenetetramine or a melamine derivative is used. Examples of the melamine derivative include methylol melamine, a partially etherified product of methylol melamine, a condensate of melamine, formaldehyde and methanol, and among them, hexamethoxymethyl melamine is particularly preferable.

  The blending amount of the methylene acceptor is preferably 0.5 to 2.5 parts by weight with respect to 100 parts by weight of the diene rubber. Further, the blending amount of the methylene donor is preferably a weight corresponding to 0.5 to 2 times the blending amount of the methylene acceptor.

  In the rubber composition of the present invention, as other compounding agents, a rubber composition for coating an organic fiber material, such as fillers such as carbon black and silica, anti-aging agent, zinc white, stearic acid, process oil, vulcanizing agent, etc. Various additives generally used in can be blended. In addition, as said vulcanizing | curing agent, sulfur is preferable and it is preferable that 1-5 weight part of sulfur is mix | blended with respect to 100 weight part of diene rubbers. The rubber composition can be prepared by kneading using a commonly used Banbury mixer, a mixer such as a roll or a kneader.

  The rubber composition comprising the above is used as a rubber for coating organic fiber materials such as nylon, polyester, and aramid. Preferably, it is used as a covering rubber (topping rubber) for a carcass of a pneumatic tire or a chafer. That is, the pneumatic tire according to the present invention includes an organic fiber reinforcement layer formed by coating an organic fiber material with the rubber composition. As such an organic fiber reinforcement layer, an organic fiber cord is used as a rubber composition. Carcass formed by coating with a material, chafers formed by coating an organic fiber fabric with a rubber composition, and the like. In particular, it is preferably used for a chafer for reinforcing a bead portion in a heavy duty tire used for a large vehicle such as a truck or a bus. In such a large heavy duty tire, a member embedded in the bead portion generally has poor heat around vulcanization, and therefore the rubber composition having a high vulcanization speed has a high productivity improvement effect. It is. In addition, the chafer has a large bending deformation in a portion disposed radially outward from the rim flange, so that the rubber composition having excellent fatigue resistance has a high effect of improving durability.

  FIG. 1 is a half sectional view of an example of a heavy duty pneumatic radial tire having such a chafer. An annular bead core (2) formed by winding a bead wire in the tire circumferential direction is embedded in the pair of left and right bead portions (1). A carcass (3) extending between the pair of bead portions (1) is provided, and the carcass (3) is a layer formed by arranging a plurality of steel cords in the tire radial direction and covering with a coating rubber. It consists of at least one layer, and both ends are locked by being rolled up around the bead core (2) from the inside of the tire to the outside in the bead portion (1).

  A chafer (5) is provided adjacent to the outside of the winding part (4) of the carcass (3) in the bead part (1). As an example, the chafer (5) is formed by coating a topping rubber on both sides of a nylon fiber cord weave, and the rubber composition is used as the topping rubber. The chafer (5) is arranged such that the cord is inclined with respect to the tire radial direction.

  The structure of the chafer is not limited to the embodiment shown in FIG. 1 and can be provided in various forms so as to protect the carcass. For example, a reinforcing layer such as a steel cord reinforcing layer may be provided adjacent to the outer surface of the carcass winding portion, and the chafer may be provided adjacent to the outer surface of the reinforcing layer.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Using a Banbury mixer, according to the composition shown in Table 1 below, each component was added and mixed to prepare rubber compositions of Examples and Comparative Examples. Each component in Table 1 is as follows.

・ Natural rubber: RSS No. 3,
SBR: styrene butadiene rubber, “SBR1502” manufactured by JSR Corporation,
・ Vulcanization accelerator CBS: N-cyclohexyl-2-benzothiazolylsulfenamide, “Noxeller CZ” manufactured by Ouchi Shinsei Chemical Co., Ltd.
・ Vulcanization accelerator TBzTD: Tetrabenzylthiuram disulfide, “Noxeller TBzTD” manufactured by Ouchi Shinsei Chemical Co., Ltd.,
・ Vulcanization accelerator ZnBzDTC: Zinc dibenzyldithiocarbamate, “Noxeller ZTC” manufactured by Ouchi Shinsei Chemical Co., Ltd.
D-glucose: “D-(+)-glucose” manufactured by Nacalai Tesque,
Alkyl group-modified sugar derivative A: butyl-α-D-glucopyranoside, n = 3 in formula (1), “GS-AG4S” manufactured by Gunei Chemical Industry Co., Ltd.
Alkyl group-modified sugar derivative B: Octyl-α-D-glucopyranoside, n = 7 in formula (1), “GS-AG8S” manufactured by Gunei Chemical Industry Co., Ltd.
Alkyl group-modified sugar derivative C: Decyl-α-D-glucopyranoside, n = 9 in formula (1), “GS-AG10S” manufactured by Gunei Chemical Industry Co., Ltd.

  In each rubber composition, 50 parts by weight of carbon black (“Seast 300” manufactured by Tokai Carbon Co., Ltd.) and process oil (“JOMO Process P” manufactured by Japan Energy Co., Ltd.) are added to 100 parts by weight of diene rubber. -200 ") 5 parts by weight, zinc white (" Zinc Flower No. 3 "manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part by weight stearic acid (" Lunac S-25 "manufactured by Kao Corporation), anti-aging agent 6PPD ("Santflex 6PPD" manufactured by Flexis) 1 part by weight, 3 parts by weight of sulfur ("Muclon HS OT-20" manufactured by Flexis), resorcin derivative ("SUMIKANOL 620" manufactured by Sumitomo Chemical Co., Ltd.), resorcin-alkylphenol-formalin Resin) 1 part by weight, and melamine derivative (Mitsui Cytec Co., Ltd. “Sylets 963L”) Hexamethoxymethylmelamine) was blended 1 part by weight.

  About each obtained rubber composition, while measuring workability (viscosity), scorch resistance, and a vulcanization | cure speed | rate, it vulcanizes at 150 degreeC * 30 minutes, and produces the test piece of a predetermined shape, and the obtained test Using the pieces, the breaking strength, bending fatigue resistance and adhesion were measured. Each measuring method is as follows.

Processability (viscosity): The Mooney viscosity (ML1 + 4) of the unvulcanized rubber composition at 100 ° C. was measured according to JIS K6300. The result was displayed as an index indicating a ratio with the measured value of Comparative Example 1 as 100. The smaller the index, the lower the viscosity and the better the workability.

Scorch resistance: Mooney scorch test in accordance with JIS K6300 was performed using a rheometer (L-shaped rotor), and the t5 value at the time of measurement at a temperature of 125 ° C. for 1 minute was obtained. A larger value indicates better scorch resistance.

-Vulcanization speed t50: Mooney scorch test in accordance with JIS K6300 was performed using a rheometer (L-shaped rotor), and the t50 value at the time of measurement at a temperature of 150 ° C for 1 minute was obtained. A smaller value indicates a faster vulcanization rate.

-Breaking strength (MPa): A tensile test (dumbbell No. 3) was performed according to JIS K6251.

-Bending fatigue resistance: Using a Demacha bending tester in accordance with JIS K6260, it was expressed as an index indicating the ratio when the number of cracks in Comparative Example 1 was 100. The larger the value, the better the bending fatigue resistance.

-Adhesiveness: A cord member sandwiched by an evaluation rubber sheeted with a nylon cord was prepared, and two cord members were stacked and vulcanized under the conditions of 150 ° C x 20 minutes, and a 25 mm wide test piece for evaluation was prepared. Produced. A peel test in accordance with JIS K6256 was performed, and the rubber coverage of the nylon cord after peeling was visually observed and evaluated at 0 to 100%. Even when the adhesion between the nylon cord and rubber is good, the nylon may break. In that case, it was set to 100%. The larger the value, the better the adhesion.

  The results are as shown in Table 1. Compared to Comparative Example 1 as a control, Comparative Example 2 simply using a thiuram vulcanization accelerator improved the bending fatigue resistance, although the vulcanization speed was improved. I was not able to admit. In addition, although the alkyl group-modified sugar derivative was blended with the thiuram vulcanization accelerator, the vulcanization speed was greatly improved in Comparative Example 3 in which the total amount of the vulcanization accelerator was too large, but the scorch resistance was impaired. As a result, the workability deteriorated and the bending fatigue resistance also deteriorated. In Comparative Example 4, the amount of the alkyl group-modified sugar derivative was too large and the bending fatigue resistance was improved, but the workability deteriorated and the breaking strength deteriorated. In Comparative Example 5, although the blending amount of the thiuram vulcanization accelerator was too large and the vulcanization speed was improved, the scorch resistance was impaired, the workability was deteriorated, and the bending fatigue resistance was also deteriorated. In Comparative Example 6 in which glucose was blended in place of the alkyl group-modified sugar derivative, although the vulcanization rate was improved as compared with Comparative Example 1, the scorch resistance and the bending fatigue resistance were deteriorated.

  On the other hand, when it is Examples 1-8 which mix | blended predetermined amount of thiuram type | system | group vulcanization accelerators or dithiocarbamate type | system | group vulcanization accelerators as a vulcanization accelerator with an alkyl group modified sugar derivative, In addition, the vulcanization speed was increased and the bending fatigue resistance was improved without deteriorating the breaking strength and workability. Further, even in comparison with Comparative Example 2, the vulcanization speed was further increased and the bending fatigue resistance was improved without impairing workability and breaking strength.

  The rubber composition for coating an organic fiber material according to the present invention can increase the vulcanization speed and improve the fatigue resistance without impairing the workability. For example, the organic fiber provided in a pneumatic tire It can be suitably used as a covering rubber for the reinforcing layer, whereby not only tire performance but also productivity can be improved. In particular, it is suitable for a chafer for reinforcing a bead portion in a heavy duty tire used for a large vehicle such as a truck or a bus.

Claims (6)

For 100 parts by weight of diene rubber
Containing 0.5 parts by weight or more and 10 parts by weight or less of an alkyl group-modified sugar derivative obtained by reacting glucose with a primary alcohol;
Containing at least 0.1 part by weight and no more than 2.0 parts by weight of a vulcanization accelerator, and at least selected from the group consisting of a dithiocarbamate vulcanization accelerator and a thiuram vulcanization accelerator in the vulcanization accelerator A rubber composition for coating an organic fiber material, which contains one kind and 0.1 part by weight or less.   The rubber composition for coating an organic fiber material according to claim 1, wherein the alkyl group-modified sugar derivative is an alkyl-D-glucopyranoside having 1 to 25 carbon atoms in the alkyl group. The rubber composition for coating an organic fiber material according to claim 2, wherein the alkyl group-modified sugar derivative is represented by the following general formula (1).

(In the formula, n is an integer of 0 to 24.)   The rubber composition for coating an organic fiber material according to claim 3, wherein n in the general formula (1) is an integer of 0 to 12.   The pneumatic tire provided with the organic fiber reinforcement layer formed by coat | covering an organic fiber material with the rubber composition of any one of Claims 1-4.   The pneumatic tire according to claim 5, wherein the organic fiber reinforcing layer is a chafer disposed outside the carcass winding portion in the bead portion.

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