JPS6382802A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the air leak of tubeless tire, by specifying both rubber combination and thickness of an inner liner layer and extending the end part of the downward portion of a bead part to at least the inner tip of the bead part. CONSTITUTION:The thickness of an inner liner layer 6 is at least 0.5mm, and the end part of the downward portion L of a bead part is extended to a bead toe 8. Meanwhile, the inner liner layer 6 is constituted by compounded rubber made up of butyl rubber halide (at least 40 weight parts) and natural rubber or diene-family synthetic rubber. With this constitution, the internal pressure holding index can be enhanced, while the air-leak can be prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a pneumatic tire with an inner liner layer,
In particular, it relates to tubeless pneumatic radial tires.

(Prior Art) This type of tubeless pneumatic radial tire generally includes an inner liner layer on the inner surface of the tire for the purpose of air impermeability. This inner liner layer has the function of retaining the air trapped inside the tire, and as the air travels through the carcass layer, it increases the pressure of the carcass layer at the shoulder of the tire, preventing breakage between the tread and carcass layers while the tire is running. It has the function of preventing you from getting up easily. In addition, recently, steel breaker tires have become the majority of tires, and wire rust due to moisture in the air has become a major problem, but the inner liner layer blocks moisture in the air,
It also has the function of preventing wire estrus.

In order to fully fulfill these functions, the composition, thickness, and arrangement of the inner liner are important factors. When comparing air permeability based on the type of polymer, halogenated butyl rubber shows far superior air permeability compared to general-purpose rubbers such as natural rubber, styrene-butadiene rubber, and butadiene rubber.

Conventionally, a composition containing halogenated butyl rubber has been used for the inner liner layer in order to provide air permeability and to prevent water penetration, especially when a metal cord is used as the carcass layer. An example of this is the pneumatic tire described in Japanese Patent Application Laid-open No. 120501/1983.

(Problems to be Solved by the Invention) Even if a rubber composition containing halogenated butyl rubber as a rubber component is used in the inner liner layer, the mixing ratio, the thickness of the inner liner layer, and the extension length to the region below the bead are Air leakage varies greatly depending on the condition. As shown in FIG. 7, the conventional inner liner layer extends to the lower region of the bead portion in order to prevent air leakage, but does not reach the bead tip (bead toe). In other words, the inner liner layer does not sufficiently cover the inner surface of the tire up to the rim, so it is not covered with a general-purpose rubber layer (carcass rubber or chafer rubber near the bead, generally natural rubber or chafer rubber). The disadvantage is that air leaks through the diene-based synthetic rubber (styrene-butadiene rubber, butadiene rubber, etc.), and the excellent properties of the inner liner layer containing halogenated butyl rubber as a rubber component cannot be fully utilized.

(Means for Solving the Problems) The present invention aims to effectively prevent air leakage from the inner liner layer, and as a means for achieving this purpose, a carcass layer having a pair of beads and a carcass layer having a pair of beads and a carcass layer having a pair of beads. In a pneumatic tire comprising a side rubber layer and a breaker layer covering the outside of the layers, a tread rubber layer in the crown portion, and an inner liner layer in the innermost layer of the tire, the inner liner layer has a thickness of at least o,
The inner liner layer is made of 40 parts by weight or more of halogenated butyl rubber and the balance being natural rubber or diene rubber. They adopted a structure consisting of a compound with synthetic rubber.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings of FIGS. 1 to 6.

Fig. 1 shows a left half sectional view of a tubeless pneumatic radial tire which is an example of the present invention, and Figs. 2 to 6 show sectional views of the lower region of the sidewall. 3 is a sidewall rubber layer, 4 is a breaker layer, 5 is a trend rubber layer, 6 is an inner liner layer, and 7 is a stiffener.

In the present invention, the inner liner N6 has a thickness of at least 0.5 mm as shown in FIG. It has been extended.

In the case shown in FIG. 2, the lower end of the bead of the inner liner layer 6 extends about half a length from the bead toe 8 toward the bead heel 9, and as shown in FIG. The one shown extends to the bead heel 9.

What is shown in Figures 4 and 5 is the bead shown in Figures 1 and 2.
A chafer 10 is provided to cover the inner liner layer 6 at the tow 8 portion, and FIG.
0 is replaced with ablation rubber 11, and various other modifications are possible. In short, in the present invention, the end portion of the inner liner layer 6 in the region below the bead only needs to extend at least to the tip inside the bead portion.

In the present invention, the thickness of this inner liner layer is required to be at least 0.5 mm, and the reason for this limitation is that the air leakage effect is small if it is less than 0.5 mm.

Next, in the present invention, a blend of 40 parts by weight or more of halogenated butyl rubber and the balance of natural rubber or diene-based synthetic rubber, such as polyisoprene rubber, is used as the inner liner layer. In this case, the reason for using halogenated butyl rubber at 40 parts by weight or more is that if it is less than 40 parts by weight, it will not show sufficient air impermeability, and the price of the compound will increase and processability will become difficult, but it is still a great effect. This is because it cannot be obtained. The above-mentioned difficulty in processability refers to air entering the inner liner sheet during the inner liner calendering process, or air entering between the sheets, resulting in problems such as air remaining in the tire after vulcanization. It means that.

Table 1 below shows examples and comparative examples of formulations used in the inner liner used in the present invention.

Table 1 * After vulcanization, Table 2 below shows the above Comparative Examples A and B and the Invention Examples E and F.
7 (a) using an inner liner formulation of
) and the results of testing the internal pressure retention index of the tire having the structure shown in FIG. 1(b) of the present invention. However, the thickness of the inner liner layer in (al(b)) was the same.

Table 2 Tire test results The above test tires were T/L 1655R13 size, and air leakage was determined by setting the initial air pressure to 2.2 kg/cni.
The samples were left in a constant temperature room at 25°C for 60 days, and the amount of decrease in air pressure was compared. For each index, a larger number indicates better air impermeability.

(Effects of the Invention) In the present invention, the inner liner layer has a thickness of at least 0.5t++, the end of the lower region of the bead extends at least to the tip inside the bead, and the inner liner layer Since the composition was made of a compound of 40 parts by weight or more of halogenated butyl rubber and the balance being natural rubber or diene-based synthetic rubber, as is clear from the tire test results in Table 2 above, a large amount of halogenated butyl rubber was used. Even if the composition is considered to have good air impermeability, tires with a structure have a low internal pressure retention index.
The tire having structure b of the present invention has been shown to have a dramatic effect, and it has therefore been possible to provide a tire that effectively prevents air leakage from the inner liner layer.

[Brief explanation of the drawing]

Figures 1 to 6 show examples of the tire of the present invention, with Figure 1 being a sectional view of the left half of the tire, and Figures 2 to 6 being a sectional view of the lower half of the sidewall. The figure is shown below. FIG. 7 is a half sectional view of a conventional example. DESCRIPTION OF SYMBOLS 1... Bead core, 2... Carcass layer, 3... Sidewall rubber layer, 4... Breaker layer, 5... Tread rubber layer, 6... Inner liner layer, 8...
Bead toe, 9...bead heel. Figure 13 Figure 4 Procedural amendment (voluntary) November 5, 1985 Patent application No. 228777, filed in 1988 2, name of invention pneumatic tire 3, relationship with the case of the person making the amendment Patent application Hito Otsu Tire Co., Ltd. 4, Agent: 1013 Mikuriya, Higashiosaka City, Osaka Prefecture, Showa Year, Month, Day (Voluntary) 6. Subject of amendment 7, Contents of amendment (]) Page 6, lines 17-18 of the specification: The phrase "with diene-based synthetic rubber, such as polyisoprene rubber" is corrected to "with diene-based synthetic rubber." (2) On page 6, line 20, the word “air” means “
"Air" is corrected. (3) Table 1 on page 8 of the same document shall be amended as shown in the attached sheet. (4) Box 6 in the attached drawing shall be amended as per the attached sheet (
(addition of code 11, no change in content). Ha 1st Table Kasumi (G) * Chikara Ogo 6

Claims (1)

[Claims] (1) A pneumatic tire consisting of a carcass layer having a pair of beads, a side rubber layer and a breaker layer covering the outside of the carcass layer, a tread rubber layer in the crown, and an inner liner layer in the innermost layer of the tire, The inner liner layer has a thickness of at least 0.
The inner liner layer is made of 40 parts by weight or more of halogenated butyl rubber and the remainder made of natural rubber or diene-based synthetic rubber. A pneumatic tire characterized by being made of a compound with rubber.