JP2006152110A - Sealant composition for blowout prevention, and pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealant composition for blowout prevention with suppressed fluidity without blemishing sealing properties, and to provide a pneumatic tire using the sealant composition. <P>SOLUTION: This sealant composition comprises 100 pts.wt. of polyisobutylene or butyl rubber containing 0.5-2.5 mol% isoprene, 0.2-20 pts.wt. of a peroxide and 3-20 pts.wt. of a cashew-modified phenol-formaldehyde resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a puncture-preventing sealant composition that suppresses fluidity without impairing the sealing property (the performance of sealing a hole to prevent tire puncture when a hole is opened by a nail or the like) and The present invention relates to a pneumatic tire using the sealant composition.

  Conventionally, in order to improve the sealing property at the time of puncture, forming the tire inner surface with a layer of a puncture-preventing sealant composition has been performed.

However, there is a problem that the sealant composition on the inner surface of the tire flows to the center part in the tire width direction by centrifugal force during traveling, particularly at high speed, and the sealing performance of the shoulder portions on both sides of the center part becomes insufficient. . Therefore, when the viscosity of the sealant composition is increased to suppress fluidity, the sealing performance is lowered.
JP-A-53-55802

  An object of the present invention is to provide a puncture-preventing sealant composition that suppresses fluidity without impairing sealability, and a pneumatic tire using the sealant composition.

  The puncture-preventive sealant composition of the present invention comprises 100 parts by weight of butyl rubber having a polyisobutylene or isoprene content of 0.5 to 2.5 mol%, 0.2 to 20 parts by weight of peroxide, and 3 to 20 cashew-modified phenol formaldehyde resins. It is characterized by comprising a weight part.

  The pneumatic tire of the present invention is characterized by including a heat treatment layer of the puncture-preventing sealant composition.

  As described above, in the present invention, the peroxide is blended with polyisobutylene (PIB) or butyl rubber (IIR) having a low isoprene content of 0.5 to 2.5 mol%, so that the puncture-preventing sealant composition of the present invention is used. When forming a part of the tire and vulcanizing the tire, PIB or IIR having a low isoprene content is decomposed by the peroxide and flows to exhibit a sealing property. Since the modified phenol formaldehyde resin is blended, the cashew modified phenol formaldehyde resin is crosslinked and cured by the heat during vulcanization to form a three-dimensional network structure, holding the decomposition fluid by peroxide as a matrix, and the decomposition fluid This will suppress the fluidity. For this reason, in this invention, it becomes possible to make sealing performance and fluidity compatible.

  As described above, the puncture-preventing sealant composition of the present invention comprises 100 parts by weight of butyl rubber having a polyisobutylene or isoprene content of 0.5 to 2.5 mol%, 0.2 to 20 parts by weight of peroxide, and cashew-modified phenol. Since it contains 3 to 20 parts by weight of formaldehyde resin, it is possible to suppress fluidity without impairing the sealing property.

  FIG. 1 is a half sectional view in the tire meridian direction showing an example of the pneumatic tire of the present invention.

  In FIG. 1, a carcass layer 2 is mounted between bead cores 3 and 3 in a pair of left and right bead portions 1 and 1, and two belt layers 5 and 5 are arranged in the tire circumferential direction on the outer side of the carcass layer 2 in a tread 4. It arrange | positions over the tire 1 circumference.

  On the inner side of the tire of the carcass layer 2, a heat treatment layer 6 of a puncture-preventing sealant composition is disposed further on the inner side of the inner liner layer to form an inner surface of the tire. The heat treatment layer 6 of the puncture-preventing sealant composition is provided on the inner surface of the tire corresponding to at least the tread portion so as to extend one turn in the tire circumferential direction. The heat treatment layer 6 may be provided so as to extend to the inner surface of the sidewall portion. The heat treatment layer 6 is formed by disposing a puncture-preventing sealant composition on the inner surface of a green tire (raw tire) and heating and vulcanizing the green tire. Accordingly, the term “heat treatment” as used herein means that the puncture-preventing sealant composition is treated with heat during vulcanization of the green tire.

  A cover rubber sheet may be further provided on the tire inner side of the heat treatment layer 6 of the puncture-preventing sealant composition, and the tire inner surface corresponding to at least the tread portion may be formed by the cover rubber sheet. By disposing the cover rubber sheet, the fluidity after heat treatment of the puncture-preventing sealant composition can be further suppressed. The material of the cover rubber sheet is not specified and may be the same as the inner liner layer, for example.

  An anti-puncture sealant composition is made of 100 parts by weight of polyisobutylene (PIB) or butyl rubber (IIR) having an isoprene content of 0.5 to 2.5 mol%, 0.2 to 20 parts by weight of peroxide, and cashew-modified phenol formaldehyde resin. 3 to 20 parts by weight.

  PIB is not specified, and for example, a commercially available product having a viscosity average molecular weight of about 50,000 to 100,000 may be used.

  Butyl rubber (IIR), or isobutylene-isoprene rubber, has a low isoprene content of 0.5 to 2.5 mole percent. This is because IIR having a higher isoprene content is crosslinked by peroxide rather than decomposed during vulcanization.

  Any peroxide may be used. For example, p-chlorobenzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide and the like. This peroxide is blended in an amount of 0.2 to 20 parts by weight with respect to 100 parts by weight of the PIB or IIR. This is because this blending amount is appropriate for the decomposition of PIB or IIR.

  Cashew-modified phenol formaldehyde resin is a cashew-modified phenol aldehyde resin having the following formula.

  As the cashew-modified phenol formaldehyde resin, commercially available products such as Sumitrite Gin PR-150 manufactured by Sumitomo Bakelite Co., Ltd. and Phenolite AA-1419 manufactured by Dainippon Ink & Chemicals, Inc. may be used. This cashew-modified phenol formaldehyde resin is blended in an amount of 3 to 20 parts by weight based on 100 parts by weight of the PIB or IIR. This is because the fluidity of the cracked fluid during vulcanization is appropriate at this blending amount.

  In addition to the above-described blending components, the puncture-preventing sealant composition of the present invention is generally blended for tires such as reinforcing agents such as carbon black, fillers, anti-aging agents, softeners, and other general rubbers. Various additives can be blended. The puncture-preventing sealant composition of the present invention can be produced by mixing the above-described blending components using a known rubber kneading machine (for example, a roll, a Banbury mixer, a kneader, etc.).

  A sealant composition for preventing puncture was prepared with the blending contents (parts by weight) shown in Table 1, and the inner surface of the pneumatic tire was formed with a heat treatment layer of this composition (layer thickness of the composition 4 mm), and sealed as follows. And high-speed fluidity were evaluated (Examples 1 to 3, Comparative Examples 1 and 2). The results are shown in Table 1.

Sealing probability when five N65 nails are driven into the tread of a pneumatic tire and removed.

The layer thickness change of the layer of the sealant composition for preventing puncture on the inner surface of the tire corresponding to the end position in the width direction of the belt layer of the pneumatic tire after running indoors for 1 hour at a high fluidity speed of 80 km / h. In Table 1, “Δ” represents a case where the layer thickness is reduced.

  In Table 1, Comparative Example 1 is a case where no cashew-modified phenol formaldehyde resin is added to the puncture-preventing sealant composition, and Comparative Example 2 is a case where the amount of cashew-modified phenol formaldehyde resin is too large.

  As is clear from Table 1, Comparative Example 1 has a large thickness reduction (large fluidity) compared to Examples 1 to 3, and Comparative Example 2 has too much compounding amount of cashew-modified phenol formaldehyde resin. Thus, the fluidity of the puncture-preventing sealant composition is too low, and it becomes difficult for the nail to be entrained in the hole when the nail is pulled out.

It is a tire meridian direction half sectional view showing an example of the pneumatic tire of the present invention.

Explanation of symbols

1 Bead part 2 Carcass layer 3 Bead core 4 Tread 5 Belt layer 6 Heat treatment layer

Claims (4)

A sealant composition for preventing puncture, comprising 100 parts by weight of polyisobutylene or isoprene content of 0.5 to 2.5 mol% of butyl rubber, 0.2 to 20 parts by weight of peroxide, and 3 to 20 parts by weight of cashew-modified phenol formaldehyde resin. object. A puncture-preventing sealant composition comprising 100 parts by weight of polyisobutylene or isoprene content of 0.5 to 2.5 mol% of butyl rubber, 0.2 to 20 parts by weight of peroxide, and 3 to 20 parts by weight of cashew-modified phenol formaldehyde resin A pneumatic tire provided with a heat treatment layer. The pneumatic tire according to claim 2, wherein a tire inner surface corresponding to at least a tread portion is formed by a heat treatment layer of the puncture-preventing sealant composition. The pneumatic tire according to claim 3, wherein a cover sheet rubber is disposed inside the tire in the heat treatment layer of the puncture-preventing sealant composition that forms the tire inner surface, and the tire inner surface corresponding to at least the tread portion is formed by the cover sheet rubber. tire.

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