JP2009155501A - Rubber composition for inner tube and rubber composition for inner liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for an inner tube and a rubber composition for an inner liner hardly generating cracks in the rubber and having excellent productivity. <P>SOLUTION: The rubber composition for the inner tube or the rubber composition for the inner liner comprises 100 pts.wt. of a rubber component, ≤2 pts.wt. of zinc oxide and 1-5 pts.wt. of a mixed resin composed of aliphatic and aromatic resins. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a rubber composition for an inner tube or an inner liner of a tire.

Conventionally, butyl rubber that has low air permeability and can hold air has been used for inner tubes and inner liners of tires. Among butyl rubbers, it is common to use halogenated butyl rubber such as brominated butyl rubber in order to shorten the vulcanization time (Patent Document 1). Furthermore, metal oxides such as zinc oxide are used as an improvement in permanent elongation and as a vulcanizing agent.

Such a metal oxide is blended by finish kneading so that crosslinking does not start during kneading when kneading with rubber. However, when blended by finish kneading, it is difficult to uniformly disperse, and cracks may occur from the agglomerates generated when not uniformly dispersed. There is a problem that arises. In addition, if the mixture is sufficiently kneaded so that no agglomerates are generated, there arises a problem that productivity decreases.

JP2007-84610

An object of the present invention is to provide a rubber composition for an inner tube and a rubber composition for an inner liner that are less prone to cracks in rubber and that are excellent in productivity.

The present invention relates to a rubber composition for an inner tube containing 2 parts by weight or less of zinc oxide and 1 to 5 parts by weight of a mixed aliphatic and aromatic resin with respect to 100 parts by weight of a rubber component.

The present invention also relates to a rubber composition for an inner liner containing 2 parts by weight or less of zinc oxide and 1 to 5 parts by weight of a mixed aliphatic and aromatic resin with respect to 100 parts by weight of a rubber component.

Furthermore, the present invention relates to a pneumatic tire having an inner tube made of the rubber composition for an inner tube and a pneumatic tire having an inner liner made of the rubber composition for an inner liner.

According to the present invention, in the rubber composition for an inner tube and the rubber composition for an inner liner, the zinc oxide is suppressed to 2 parts by weight or less, and 1 to 5 parts by weight of an aliphatic and aromatic mixed resin is contained. Cracks are less likely to occur inside, and productivity can be improved.

In the rubber composition for an inner tube and the rubber composition for an inner liner of the present invention, 2 parts by weight or less of zinc oxide and a total of 1 to 5 parts by weight of an aliphatic and aromatic mixed resin with respect to 100 parts by weight of the rubber component Including.

As the rubber component, butyl rubber (IIR) and halogenated butyl rubber excellent in air impermeability are preferable. Examples of the halogenated butyl rubber include chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), and fluorinated butyl rubber (F-IIR), with Br-IIR being preferred.

It can also be used by mixing with other rubber components. Other rubber components include styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), butadiene rubber (BR), isoprene rubber (IR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR ), Acrylonitrile-butadiene rubber (NBR), natural rubber (NR), isoprene rubber (IR) and the like.

The compounding amount of zinc oxide is 2 parts by weight or less with respect to 100 parts by weight of the rubber component. If the blending amount exceeds 2 parts by weight, the dispersibility of zinc oxide at the time of kneading is lowered and the cracking property and bending performance are inferior. When used for the inner tube, the upper limit of the amount is preferably 2 parts by weight or less, and the lower limit is preferably 0.5 parts by weight or more, and more preferably 1 part by weight or more. When used for the inner liner, the upper limit of the amount is preferably 1 part by weight or less, and the lower limit is more preferably 0.2 parts by weight or more. If the lower limit of the blending amount is too low, crosslinking is insufficient, permanent elongation tends to increase, and tire pressure tends to be unbearable.

The aliphatic and aromatic mixed resin is one in which both components are introduced when the resin is produced, and examples of the homogenizing agent include stratol 40MS and stratol 60NS. Of these, Stratol 40MS is preferable in terms of filler dispersion and air impermeability.

In the present invention, by using an aliphatic and aromatic mixed resin as the resin, the dispersibility of zinc oxide can be improved and the crack resistance can be improved.

The amount of the mixed aliphatic and aromatic resin is preferably 1 part by weight or more and more preferably 2 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 1 part by weight, sufficient hardness cannot be obtained, and there is a tendency that the tire cannot withstand the air pressure during use of the tire. The blending amount is preferably 5 parts by weight or less, and more preferably 4 parts by weight or less. When the blending amount exceeds 5 parts by weight, the viscosity of the rubber tends to increase and the processability tends to decrease.

In addition to the rubber component, zinc oxide, aliphatic and aromatic mixed resin, the rubber composition of the present invention may be filled with sulfur, a vulcanization accelerator, carbon black, silica, calcium carbonate, etc., if necessary. Additives such as additives, plasticizers, anti-aging agents, process oils and waxes can be blended.

When carbon black is blended, the blending amount of carbon black is preferably 40 parts by weight or more, more preferably 50 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 40 parts by weight, the reinforcing property tends to be lowered. Moreover, the upper limit of the amount is preferably 80 parts by weight or less, more preferably 70 parts by weight or less. If the blending amount exceeds 70 parts by weight, the crack resistance performance tends to decrease.

Specific examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil.

When blending the process oil, the blending amount of the process oil is preferably 2 parts by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 2 parts by weight, the crack resistance performance tends to decrease. The upper limit of the amount is preferably 25 parts by weight or less, more preferably 20 parts by weight or less. When the blending amount exceeds 25 parts by weight, the dimensional growth property tends to increase.

The rubber composition for an inner tube of the present invention is used for manufacturing a tire and can be formed into a tire by a usual method. That is, if necessary, the rubber composition for a tube of the present invention blended with the additive is extruded in accordance with the shape of the tire tube at an unvulcanized stage, and is processed on a tire molding machine by a usual method. An unvulcanized tire is formed by molding. The unvulcanized tire is heated and pressurized in a vulcanizer to produce a tire.

Here, an inner tube means what is arrange | positioned between a tire and a rim | limb. Specific examples of tires include bicycle tires, automobile tires, motorcycle tires, agricultural vehicle tires, and the like.

The rubber composition for an inner liner of the present invention is used for manufacturing a tire and can be made into a tire by a usual method. That is, if necessary, the rubber composition for an inner liner of the present invention blended with the additive is extruded in accordance with the shape of the inner liner of the tire at an unvulcanized stage, and is usually used on a tire molding machine. An unvulcanized tire is formed by molding by the method. The unvulcanized tire is heated and pressurized in a vulcanizer to produce a tire.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not restrict | limited only to these.

Various chemicals used in the examples are described below.
(material)
Butyl rubber IIR: IIR268 manufactured by ExxonMobil
Brominated butyl rubber Br-IIR: 2255 manufactured by ExxonMobil
Carbon black N660: carbon black N660 manufactured by Mitsubishi Chemical Corporation
Carbon Black N550: Carbon Black N550 manufactured by Cabot Corporation
Process oil: Process P200 manufactured by Japan Energy Co., Ltd.
Mixed resin: Straftol 40MS manufactured by Schill & Seilacher
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. TBZTD: TBZTD (tetrabenzylthiuram disulfide) manufactured by Flexis Co., Ltd.
Vulcanization accelerator M: Noxeller MP manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator DM: NOCELLER DM-P manufactured by Ouchi Shinsei Chemical Co., Ltd.

Examples 1-3 and Comparative Examples 1-4
Among the blending contents shown in Table 1, various chemicals excluding sulfur and a vulcanization accelerator are kneaded with a Banbury mixer, and sulfur and various vulcanization accelerators are added to the obtained kneaded material, and then open rolls are used. It knead | mixed and the unvulcanized rubber composition was obtained. The unvulcanized rubber composition was press vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized rubber sample.

The tube produced from each rubber composition was mounted on a 10.00R20 size tire and run on a drum, and the number of cracks in the tube and the dimensional growth were evaluated. As for the cracking property, a five-step evaluation was performed with 1 having a large number of cracks and 5 having a small number of cracks. Further, the dimension growth property was calculated by the volume change rate when the comparative example 1 was set to 100. Those with a large index are inferior in dimension growth. Each test result is shown in Table 1.

From the results in Table 1, it can be seen that the inner tube obtained using the composition of the present invention is excellent in cracking properties and dimensional growth properties.

Examples 4-7 and Comparative Examples 5-9
Among the blending contents shown in Table 2, various chemicals excluding sulfur and vulcanization accelerators are kneaded with a Banbury mixer, and sulfur and various vulcanization accelerators are added to the obtained kneaded material, and then open rolls are used. It knead | mixed and the unvulcanized rubber composition was obtained. The unvulcanized rubber composition was press vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized rubber sample.

The inner liner produced from each rubber composition was mounted on a TL245 / 70R19.5 14PR size tire, each tire was heat aged at 80 ° C. for 14 days, and then run on a drum. The number of cracks was compared and the bleeding of the inner liner was evaluated. As for the cracking property, a five-step evaluation was performed with 1 having a large number of cracks and 5 having a small number of cracks. In addition, the blurring property was evaluated as x when the shadow of the ply cord was visible and ◯ when it was not visible. The test results are shown in Table 2.

From the results in Table 2, it can be seen that the inner liner obtained using the composition of the present invention is excellent in cracking and bleeding.

Claims (4)

A rubber composition for an inner tube containing 2 parts by weight or less of zinc oxide and 1 to 5 parts by weight of an aliphatic and aromatic mixed resin with respect to 100 parts by weight of the rubber component. A rubber composition for an inner liner containing 2 parts by weight or less of zinc oxide and 1 to 5 parts by weight of a mixed resin of aliphatic and aromatic with respect to 100 parts by weight of the rubber component. A pneumatic tire having an inner tube made of the rubber composition for an inner tube according to claim 1. A pneumatic tire having an inner liner made of the rubber composition for an inner liner according to claim 2.