JP2006063093A - Rubber composition for tread - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a tread, gentle to earth and preparing ourselves for the decrease of the supplying amount of the petroleum by increasing the content ratio of resources other than petroleum, and exhibiting a sufficient running performance on a wet road surface and dry road surface. <P>SOLUTION: This rubber composition for the tread is provided by containing a filler consisting of ≥8 pt. wt. resin and ≥80 pt. wt. white-colored filler based on 100 pts. wt. rubber component containing ≥80 wt.% natural rubber or epoxidized natural rubber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition for a tread that assumes an oil exhaustion time.

In recent years, environmental issues have become more important, regulations on the suppression of CO ₂ emissions have been strengthened, and petroleum feedstocks are limited and the supply amount has been decreasing year by year. For this reason, oil prices are expected to rise in the future, and there are limits to the use of raw materials made of petroleum resources such as styrene butadiene rubber and carbon black. Therefore, assuming that oil will be depleted in the future, it will be necessary to use non-oil resources such as natural rubber, silica, and white fillers such as calcium carbonate. However, with a tread composition mainly composed of natural rubber, the running performance on wet and dry road surfaces is inferior to that of styrene butadiene rubber which is usually used. Therefore, there is a method of improving the running performance on the wet road surface by using a white filler such as silica, calcium carbonate, aluminum hydroxide as the filler, but in that case, the running performance on the dry road surface becomes insufficient.

  Patent Document 1 discloses a technique that indicates a tire raw material that is assumed when oil is depleted, but does not disclose a tread rubber composition that exhibits sufficient running performance on wet and dry road surfaces. .

JP 2003-63206 A

  The present invention provides a rubber composition for a tread of a tire that is sufficient for the earth by increasing the content ratio of non-petroleum resources, and exhibits sufficient running performance on wet road surfaces and dry road surfaces in preparation for a decrease in the future supply of oil. The purpose is to provide.

  The present invention contains 8 parts by weight or more of resin and 80% by weight or more of a white filler based on 100 parts by weight of a rubber component containing 80% by weight or more of natural rubber and / or epoxidized natural rubber. The present invention relates to a rubber composition for treads.

  The resin is preferably derived from nature.

  It is preferable that the epoxidized natural rubber has an epoxidation rate of 12 mol% or more.

  According to the present invention, it is possible to provide a rubber composition for a tread which is gentle to the earth by increasing the content ratio of non-petroleum resources and used for a tire in preparation for a decrease in the supply amount of petroleum in the future. A tire obtained from a material exhibits excellent running performance on wet and dry road surfaces.

  The tread rubber composition of the present invention comprises a rubber component, a resin and a filler.

  The rubber component in the rubber composition for treads of the present invention comprises natural rubber (NR) and / or epoxidized natural rubber (ENR).

  As the epoxidized natural rubber, commercially available epoxidized natural rubber may be used, or natural rubber may be epoxidized. The method for epoxidizing natural rubber is not particularly limited, and can be carried out using a method such as a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, or a peracid method. Examples thereof include a method of reacting natural rubber with an organic peracid such as peracetic acid or performic acid.

  The average epoxidation rate of the epoxidized natural rubber is preferably 12 mol% or more, more preferably 15 mol% or more. If the average epoxidation rate is less than 12 mol%, the friction coefficient on wet and dry road surfaces tends to be low. Moreover, it is preferable that the average of an epoxidation rate is 50 mol% or less, and it is more preferable that it is 40 mol% or less. When the average of the epoxidation rate exceeds 50 mol%, the glass transition point increases due to the combined use with the resin, and the embrittlement performance at low temperatures tends to be inferior.

  The content of natural rubber and / or epoxidized natural rubber in the rubber component is 80% by weight or more, preferably 90% by weight or more. When the content is less than 80% by weight, the ratio of non-oil resources is small. The content of natural rubber and / or epoxidized natural rubber in the rubber component is particularly preferably 100% by weight.

  In addition to natural rubber and epoxidized natural rubber, rubber such as styrene butadiene rubber, butyl rubber, halides of copolymers of isobutylene and p-methylstyrene can be used as the rubber component. Therefore, it is preferably made of natural rubber and epoxidized natural rubber.

  Examples of the filler used in the rubber composition for a tread of the present invention include silica, calcium carbonate, sericite, carbon black, aluminum hydroxide, and clay. As the tread rubber composition of the present invention, it is preferable to use a white filler such as silica, calcium carbonate or sericite. By using these white fillers, unlike the case of fillers such as carbon black, the effect of reducing rolling resistance and increasing the ratio of non-petroleum resources can be obtained.

  The content of the white filler in the filler is 80% by weight or more, preferably 90% by weight or more. If the content is less than 80% by weight, the ratio of non-petroleum resources decreases, which is not preferable. The content of the white filler is preferably 100% by weight.

  When silica is used as the white filler, it is preferable to use a silane coupling agent in combination.

  It is preferable that the compounding quantity of a silane coupling agent shall be 4-20 weight part with respect to 100 weight part of silica. If the blending amount is less than 4 parts by weight, the wear resistance tends to deteriorate, and if it exceeds 20 parts by weight, the wear resistance also tends to deteriorate in that case.

  The rubber composition for a tread of the present invention contains a resin as a plasticizer.

  Generally, plasticizers such as mineral oil and petroleum oils such as aromatic oil and paraffin oil are used in order to improve the processability of rubber or to further enhance the grip performance. Further, by increasing the amount of anti-aging agent and wax usually used in the rubber industry, the rubber can be plasticized and the grip performance can be improved. Since the plasticizer, the anti-aging agent and the wax are extracted with an acetone solvent, they are used as an acetone extract. Grip characteristics can be improved by using the acetone extract to some extent. Furthermore, by using a resin that can improve the glass transition point as an acetone extract, the running performance on a dry road surface can be greatly improved.

  Resins include aromatic petroleum resin (resin using C9 fraction), coumarone indene resin (coal coumarone indene resin etc.), terpene resin, aromatic modified terpene resin (natural aromatic terpene etc.), rosin resin, phenol Resin, petroleum resin (resin by C5 fraction) and the like. Among them, a resin (naturally derived) obtained from natural resources other than petroleum such as natural aromatic terpene and coal coumarone indene resin is preferable.

  The softening point of the resin is preferably 50 ° C. or higher, and more preferably 80 ° C. or higher. When the softening point is less than 50 ° C., the tackiness in the manufacturing process becomes strong, and the work in manufacturing the tire tends to be difficult. The softening point of the resin is preferably 150 ° C. or less, and more preferably 140 ° C. or less. When the softening point exceeds 150 ° C., the wet grip performance tends to be insufficient, and the merit of blending the resin tends to be lost.

  The content of the resin is 8 parts by weight or more, preferably 10 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content is less than 8 parts by weight, the effect of improving the grip performance is reduced. The content is 50 parts by weight or less, preferably 35 parts by weight or less. When the content exceeds 50 parts by weight, the hardness increases.

  The rubber composition for a tread of the present invention can use a softening agent such as aromatic oil or mineral oil as a plasticizer other than the resin.

  The rubber composition for a tread of the present invention can contain a wax and an antiaging agent that are generally used in the rubber industry.

  The content of the acetone extract (total amount of plasticizer, anti-aging agent and wax) in the rubber composition for treads of the present invention is preferably 8% by weight or more in the rubber composition, and is preferably 10% by weight or more. More preferably, it is more preferably 13% by weight or more. If the content is less than 8% by weight, the running performance on dry and wet road surfaces tends to be insufficient. The content of acetone extract is preferably 25% by weight or less, and more preferably 22% by weight or less. When the content exceeds 25% by weight, the wear resistance tends to deteriorate.

  The rubber composition for a tread of the present invention contains stearic acid, zinc oxide, a vulcanizing agent, and a vulcanization accelerator in addition to the rubber component, filler, resin, silane coupling agent, wax and anti-aging agent. be able to.

  The glass transition point of the rubber composition for a tread of the present invention is preferably −50 ° C. or higher, and more preferably −40 ° C. or higher. If the glass transition point is less than −50 ° C., the running performance on dry and wet road surfaces tends to be insufficient. The glass transition point is preferably 0 ° C. or lower, more preferably −5 ° C. or lower. When the glass transition point exceeds 0 ° C., the embrittlement temperature increases and the tire may crack on a low-temperature road surface.

  The rubber composition of the present invention is used for a tread among tire members.

  By using the rubber composition for a tread of the present invention, a tire containing a tread composed of the rubber composition can be produced by a usual method. That is, the rubber composition for a tread of the present invention, which is blended with the chemicals as necessary, is extruded according to the shape of the tread of the tire at an unvulcanized stage, and molded by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

The various chemicals used in the examples are described in detail below.
NR: RSS # 1
SBR: Nipol 1502 manufactured by ZEON CORPORATION
ENR-25: Epoxidized natural rubber manufactured by GATHRIE POLYMER SDN. BHD (epoxidation rate: 25 mol%)
Carbon black: Show Black N220 from Showa Cabot Corporation
Silica: Ultrasil VN3 manufactured by Tegussa (BET specific surface area: 175 m ² / g)
Silane coupling agent: Si-69 manufactured by Tegussa
Aromatic oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Mineral oil: Diana Process PA32 manufactured by Idemitsu Kosan Co., Ltd.
Vegetable oil: Refined palm oil J (S) manufactured by Nissin Oil Co., Ltd.
Petroleum resin: Neopolymer 140 manufactured by Nippon Petrochemical Co., Ltd. (softening point: 140 ° C.)
Natural aromatic terpene: TO115 manufactured by Yashara Chemical Co., Ltd. (softening point: 115 ° C.)
Coal coumarone indene resin: Escron G90 (softening point: 90 ° C) manufactured by Nippon Steel Chemical Co., Ltd.
Wax: Sannoc Wax anti-aging agent manufactured by Ouchi Shinsei Chemical Industry Co., Ltd .: Ozonon 6C manufactured by Seiko Chemical Co., Ltd.
Stearic acid: Zinc stearate manufactured by NOF Corporation: Zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. TBBS: Ouchi Shinsei Chemical Industry ( Noxeller NS made by
Vulcanization accelerator DPG: Noxeller D manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

  Among these chemicals, non-petroleum resources are NR, ENR, silica, sulfur, silane coupling agent, vegetable oil, natural aromatic terpene, coal coumarone indene resin, stearic acid, and zinc oxide.

Examples 1 to 10 and Comparative Examples 1 to 4
Various chemicals other than sulfur and vulcanization accelerators listed in Table 1 were charged into a 1.7 L Banbury manufactured by Kobe Steel, Ltd., and kneaded at 77 rpm until reaching 145 ° C.

  To the obtained kneaded product, sulfur and a vulcanization accelerator were blended in the amounts shown in Table 1, and kneaded at 80 ° C. for 6 minutes with an open roll to obtain an unvulcanized product.

  The unvulcanized product was formed into a tread shape on a tire molding machine and bonded to another tire member to produce an unvulcanized tire. A tire was manufactured by vulcanizing it at 160 ° C. for 20 minutes. The following tests were performed using the obtained tires.

(Braking test)
The obtained tire was mounted on a vehicle, the braking stop distance from 100 km / h on the dry asphalt road surface and the wet asphalt road surface was measured, and the friction coefficient μ was determined from the measured value. The index was displayed with μ in Comparative Example 1 as 100. The larger the index, the better the performance.

  The results are shown in Table 1. In addition, the acetone extract of Table 1 indicates the content of acetone extract (petroleum resin, natural aromatic terpene, coal coumarone indene resin, wax and anti-aging agent) in the rubber composition. Indicates the content of non-petroleum resources in the rubber composition.

Claims (3)

For 100 parts by weight of a rubber component containing 80% by weight or more of natural rubber and / or epoxidized natural rubber,
A rubber composition for a tread containing a resin comprising 8 parts by weight or more of a resin and 80% by weight or more of a white filler. The rubber composition for a tread according to claim 1, wherein the resin is naturally derived. The rubber composition for a tread according to claim 1 or 2, wherein the epoxidized natural rubber has an epoxidation rate of 12 mol% or more.