JP2012166712A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weighted tire of excellent performance as a result of its becoming capable of sufficiently inhibiting occurrence of residual air, with respect to a radial tire using inner liner rubber of divided structure.SOLUTION: The pneumatic radial tire is provided with respective layers of inner liner, ply material, and rubber material being provided from the innermost layer side in the order. The inner liner is consisted of a first inner liner made of a butyl rubber-based rubber composition of butyl rubber series, and a second inner liner made of a NR (natural rubber)-based rubber composition, provided on the outer surface of the first inner liner, while the second inner liner has its central part divided and removed therefrom, with its ply material sticking surface having a slit-processing provided across the whole length in the width direction, with the ply material having pricking-processing being provided thereon.

Description

  The present invention relates to a pneumatic radial tire, and more particularly, to a pneumatic radial tire that uses a split inner liner to reduce weight.

  In a pneumatic radial tire, an inner liner is generally arranged in the innermost layer for the purpose of suppressing permeation of air filled in the tire, and a carcass ply, a belt ply (breaker), etc. are disposed on the inner liner. A ply material is attached, and a rubber material or the like is further provided to form a tire.

  The inner liner is made of a rubber composition, and is usually a first inner liner disposed between the left and right chafers on the former side, and a second inner layer disposed on the first inner liner across the chafer. It has a two-layer structure with an inner liner.

  The two-layer structure of the inner liner will be described with reference to FIG. FIG. 3 is a view for explaining a two-layer structure of the inner liner. In FIG. 3, 52 is a chafer, 53 is a first inner liner, and 54 is a second inner liner.

  FIG. 3 (a) shows the structure of the inner liner used until about 10 years ago. Both the first inner liner 53 and the second inner liner 54 are made of NR (natural rubber) rubber. A composition is used. The central portion of the first inner liner 53 is divided and removed (divided inner structure).

  However, after that, the use of butyl rubber having low gas permeability as the rubber material of the inner liner has been studied, and at present, as shown in FIG. 3B, a butyl rubber-based rubber composition is used as the first inner liner 53. Used to suppress the permeation of air and maintain the tire air pressure sufficiently. On the other hand, since the butyl rubber-based rubber composition is inferior in adhesiveness with the ply material attached on the inner liner, the NR rubber composition excellent in adhesiveness with the ply material is used as the second inner liner 54. It is used as a tie gum layer.

  However, in recent years, the demand for weight reduction of tires has become stronger, and in order to meet this demand, it has been studied to reduce the weight of the inner liner.

  As a means for reducing the weight, it is conceivable to divide and remove the central portion of the second inner liner 54 to obtain a divided inner structure as shown in FIG.

  However, in the case of such a divided inner structure, since the divided portion of the second inner liner 54 becomes a space, in the subsequent ply material attaching step, the first inner liner 53 and the ply material 55 are interposed. As a result, an air pool 56 as shown in FIG. The generation of the remaining air is not preferable because it causes a defect during vulcanization molding.

  Various techniques have been proposed for suppressing the occurrence of remaining air, but it cannot be said that sufficient techniques have been proposed yet (for example, Patent Documents 1 and 2).

JP 2005-238654 A JP 2008-302860 A

  Accordingly, an object of the present invention is to provide a tire with excellent performance that is capable of sufficiently suppressing the generation of remaining air in the radial tire having the above-described structure and, as a result, is reduced in weight.

The invention described in claim 1
Each layer of the inner liner, ply material, rubber material is a pneumatic radial tire provided in order from the innermost layer side,
The inner liner is composed of a first inner liner made of a butyl rubber rubber composition and a second inner liner provided on the outer surface of the first inner liner and made of an NR rubber composition. And
In the second inner liner, the central portion is divided and removed, and the ply material attachment surface is subjected to slit processing over the entire length in the width direction.
Further, in the pneumatic radial tire, the ply material is subjected to a wicking process.

The invention described in claim 2
2. The pneumatic radial tire according to claim 1, wherein the priming process is performed at an interval of 30 to 100 mm.

The invention according to claim 3
The slit processing is slit processing in which slits having a width of 0.2 to 2.0 mm and a depth of 0.2 to 0.8 mm are applied at a slit interval of 30 to 100 mm. A pneumatic radial tire according to claim 2.

  According to the present invention, air can be surely removed in the ply attaching step, and generation of remaining air can be sufficiently suppressed. As a result, it is possible to provide a pneumatic radial tire in which the occurrence of defects is reduced and the weight is reduced with stable quality.

It is a figure which shows typically the state by which the slit process was given to the division | segmentation inner liner. It is a perspective view which shows the state by which the pricking process was given to the ply material. It is a figure explaining the 2 layer structure of an inner liner.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

1. Divided Inner Liner FIGS. 1A and 1B are diagrams schematically showing a state in which the divided inner liner is slitted, in which FIG. 1A is an overall perspective view, and FIG. 1B is a cross-sectional view of a slit portion. In FIG. 1, 1 is a first inner liner made of a butyl rubber-based rubber composition, and 2 is a second inner liner (tie gum layer) made of an NR-based rubber composition.

  As shown in FIG. 1A, the second inner liner 2 is laminated with the first inner liner 1 in a state where the central portion is divided and removed. Then, the surface of the second inner liner 2 (the surface opposite to the surface laminated with the first inner liner 1) is subjected to slit processing over the entire length in the width direction at a predetermined interval D, and the slit A portion 21 is provided.

  Thus, in the present embodiment, since the central portion of the second inner liner 2 is divided and removed, the inner liner can be reduced in weight, and further, the tire can be reduced in weight.

  Since the slit 21 is provided on the surface of the second inner liner 2, the slit is used when a ply material such as a carcass ply or a belt ply (breaker) is applied, or when a cover is shaped after the application. The air escapes along the line and the occurrence of remaining air can be suppressed. As a result, the occurrence of defects due to the remaining air can be sufficiently suppressed, and a tire with excellent performance can be provided.

  The slit interval D is preferably 30 to 100 mm. If it is less than 30 mm, the number of slits is too large, so that the function as a tie gum layer cannot be fully exhibited. On the other hand, if it exceeds 100 mm, the air can not be sufficiently removed, and there is a possibility that air remains. More preferably, it is about 50 mm.

  As shown in FIG. 1 (b), the slit 21 is formed in a groove shape having a triangular cross section having a depth B and a width C, and air passes through this groove.

  The depth B is preferably 0.2 to 0.8 mm. If it is less than 0.2 mm, it is too shallow and there is almost no distance from the ply material. On the other hand, if it exceeds 0.8 mm, it is too deep and air may accumulate in the slit portion. More preferably, it is about 0.5 mm.

  Further, the width C is preferably 0.2 to 2.0 mm. If it is less than 0.2 mm, the slit width is too thin, and there is a risk that the air will not escape sufficiently. On the other hand, if it exceeds 2.0 mm, the slit width is too wide, so that air may accumulate in the slit portion. More preferably, it is about 1 mm.

2. Ply Material A ply material shown in FIG. 2 such as a carcass ply or a belt ply (breaker) is bonded onto the divided inner liner. FIG. 2 is a perspective view showing a state in which a pricking process is performed on the ply material, in which 3 is a ply material and 31 is a pricking hole. As shown in FIG. 2, the ply material 3 is pre-kicked at a predetermined interval A, and provided with a pre-kick hole 31.

  In this way, by providing the prepicking hole 31, it is possible to more reliably suppress the generation of air remaining when the laminated inner liner is bonded or when the cover is shaped. As a result, the occurrence of defects due to the remaining air can be sufficiently suppressed.

  The interval A of the precicking is preferably 30 to 100 mm. If the thickness is less than 30 mm, the number of prikings is too large, so that the function as the ply material cannot be sufficiently exhibited. On the other hand, if it exceeds 100 mm, the air can not be sufficiently removed, and there is a possibility that air remains. More preferably, it is about 50 mm.

  In this example, a radial tire (195 / 65R15 size) of the same size as the current radial tire is manufactured using the divided inner liner and the ply material having the above-described structure, and the degree of weight reduction and the incidence of defects are reduced. This is an example of measurement.

(Current-Comparative Example 1)
The current radial tire was set as Comparative Example 1. In Comparative Example 1, an inner liner having a two-layer structure shown in FIG. 3B is used as the inner liner. In addition, the ply material is not subjected to a precicking process.

(Examples 1-7, Comparative Example 2)
As the inner liner, a split inner liner was manufactured in which 80 mm at the center of the second inner liner of Comparative Example 1 was split and removed (Comparative Example 2).

  Using this divided inner liner, slit processing shown in Table 1 was performed. In addition, the pricking process shown in Table 1 was performed on the ply material (Examples 1 to 7).

  A radial tire was produced using the divided inner liner and ply material produced under the above conditions.

(Measurement)
For each of the 200 radial tires produced according to the comparative examples and examples, the tire weight was measured and the occurrence of defects was observed.
The measurement results are shown in Table 1. In Table 1, the weight ratio is defined as the weight ratio when the weight of the current tire (Comparative Example 1) is 100.

  From the results shown in Table 1, it can be seen that the tire can be reduced by 2% compared to the current product (Comparative Example 1) by changing from the current inner liner to the split inner liner. When the split inner liner is used, when slitting or precicking is not performed (Comparative Example 2), the defect rate is 5%, which is larger than that of the current product (Comparative Example 1). It can be seen that it can be reduced by applying a priming process (Examples 1 to 7).

  In the case of the tire of Example 3, it was found that other performances were affected, but this is presumed to be due to the fact that the prepicking interval A was as narrow as 30 mm and the number of precings was increased. Further, in the case of the tire of Example 5, there was an accident that the inner was cut during molding, but since the slit depth B was as deep as 0.8 mm, it was presumed that the tire was cut during the pasting process.

  As described above, according to the present embodiment, by adopting the split inner liner subjected to the slit processing and the ply material subjected to the precicking processing, it is possible to sufficiently suppress the generation of the remaining air, and as a result, It turns out that the pneumatic radial tire reduced in weight with stable quality can be provided.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1, 53 1st inner liner 2, 54 2nd inner liner 21 Slit 3, 55 Ply material 31 Pricking hole 52 Chefer 56 Air accumulation

Claims (3)

Each layer of the inner liner, ply material, rubber material is a pneumatic radial tire provided in order from the innermost layer side,
The inner liner is composed of a first inner liner made of a butyl rubber rubber composition and a second inner liner provided on the outer surface of the first inner liner and made of an NR rubber composition. And
In the second inner liner, the central portion is divided and removed, and the ply material attachment surface is subjected to slit processing over the entire length in the width direction.
Furthermore, the ply material is subjected to a precicking process, and is a pneumatic radial tire.   2. The pneumatic radial tire according to claim 1, wherein the priming process is performed at an interval of 30 to 100 mm.   The slit processing is slit processing in which slits having a width of 0.2 to 2.0 mm and a depth of 0.2 to 0.8 mm are applied at a slit interval of 30 to 100 mm. The pneumatic radial tire according to claim 2.

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