JP2009173051A - Pneumatic tire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire and its manufacturing method for enhancing air permeation resistance and enhancing durability while suppressing increase of weight of the tire. <P>SOLUTION: Thickness of an inner liner layer 6 stuck on an inner surface of the tire is gradually made thick from a buttress part 8 to a sidewall 9 part, and is gradually made thin from the sidewall part 9 to a bead part 2. The thickness Ta of the inner liner layer 6 at the area A corresponding to the buttress part 8, the thickness Tb of the inner liner layer 6 at the area B corresponding to the sidewall part 9 and the thickness Tc of the inner liner layer 6 at the area C corresponding to the bead part 2 are made to Ta=(1.1-1.3)T, Tb=(1.4-1.7)T and Tc=(1.1-1.3)T when the thickness T of the inner liner layer at the area corresponding to the tread part is made as reference respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the same, and more particularly, to a pneumatic tire and a method for manufacturing the same that improve air permeability while suppressing an increase in weight and at the same time improve durability. .

  In general, an inner liner layer made of butyl rubber having a small air permeability coefficient is disposed on the inner surface of a tubeless pneumatic tire as an air permeation preventive layer. A conventional general measure for improving the air permeation resistance of such a pneumatic tire has been to increase the thickness of the inner liner layer over the entire inner surface of the tire.

  However, increasing the air permeation resistance of the tire depending only on the thickness of the inner liner layer has a problem of increasing the tire weight. In particular, butyl rubber used as the inner liner layer has a higher specific gravity than other rubbers, and this problem tended to appear remarkably.

  As a countermeasure, there is a proposal that non-butyl rubber such as a specific thermoplastic resin having a small specific gravity is used as the inner liner layer while suppressing the thickness of the inner liner layer as a whole (for example, Patent Document 1). reference). However, in these proposals, a special material with no versatility is used as the inner liner layer, so the productivity of the tire is significantly reduced and the cost is increased, and measures are taken to prevent air permeation from an industrial standpoint. It wasn't always enough.

In particular, in a tire having a low cross-sectional height such as an ultra-flat tire having an aspect ratio of 40% or less, repeated bending deformation during running becomes particularly large in the vicinity of the tire maximum width position of the sidewall portion. However, compared with butyl rubber, there is a problem that the inner liner layer is easily deteriorated and durability is lowered. Therefore, none of the conventional proposals has led to a countermeasure for solving this problem.
JP 2003-200707 A

  An object of the present invention is to provide a pneumatic tire and a method for manufacturing the same that improve the air permeation resistance while simultaneously suppressing the increase in the weight of the tire.

The pneumatic tire of the present invention that achieves the above object is a pneumatic tire in which an inner liner layer for preventing air permeation is applied over the entire area inside the tire from the tread portion to the bead portion through the left and right buttress portions and the sidewall portions. The inner liner layer is gradually thickened from the buttress portion to the sidewall portion and gradually thinned from the sidewall portion to the bead portion, and the inner liner layer in the region corresponding to the tread portion. Inner in the region A corresponding to the buttress portion corresponding to 30% or less of the tire cross-section height from the outer peripheral surface of the tread portion toward the inside in the tire radial direction from the outer circumferential surface of the tread portion in a state where the liner layer is filled with the normal inner pressure It corresponds to the thickness Ta of the liner layer and 45 to 55% of the tire cross-section height. The relationship between the thickness Tb of the inner liner layer in the region B corresponding to the sidewall portion and the thickness Tc of the inner liner layer in the region C corresponding to the bead portion corresponding to 80 to 90% of the tire cross-section height. Are characterized as follows.
Ta = (1.1-1.3) T
Tb = (1.4 to 1.7) T
Tc = (1.1 to 1.3) T

  Moreover, in the structure mentioned above, it is preferable to comprise as described in (1)-(4) below.

(1) The thickness Tb of the inner liner layer is maximized at the tire maximum width position.
(2) The inner liner layer is formed of butyl rubber. In this case, it is preferable to adjust the air permeability of the inner liner layer to (4.5 to 5.5) × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg.
(3) The inner liner layer is composed of a butyl rubber layer having a thickness T and a thermoplastic resin or thermoplastic elastomer layer having a remaining thickness, and the thermoplastic resin or thermoplastic elastomer layer is It arrange | positions at the tire inner surface side of a butyl-type rubber layer. In this case, the air permeability of the butyl rubber layer is (4.5 to 5.5) × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg, and the air of the thermoplastic resin or the thermoplastic elastomer layer is obtained. The transmittance may be adjusted to (1.5 to 3.0) × 10 ⁻¹¹ cc · cm / cm ² · sec · cmHg.
(4) The flatness is set to 40% or less.

  The method for producing a pneumatic tire according to the present invention comprises three inventions. In the first invention, an unvulcanized tire is molded by attaching a butyl rubber sheet on the inner surface of the tread portion. The pneumatic tire according to claim 2 is manufactured by vulcanization in a mold.

  Further, in the second invention, a butyl rubber sheet having a uniform thickness is formed on the inner surface of the tread portion to form an unvulcanized tire, and the unvulcanized tire is vulcanized in a mold. The pneumatic tire according to claim 2 is manufactured by attaching a vulcanized butyl rubber sheet to an inner surface of a side portion of a vulcanized tire.

  Furthermore, in the third invention, a butyl rubber sheet having a uniform thickness is formed on the inner surface of the tread portion to form an unvulcanized tire, and the unvulcanized tire is vulcanized in a mold. The pneumatic tire according to claim 3 is manufactured by attaching a resin sheet made of a thermoplastic resin or a thermoplastic elastomer to an inner surface of a side part of a vulcanized tire.

  According to the pneumatic tire of the present invention, the thickness of the inner liner layer attached to the inner surface of the tire is gradually increased from the buttress portion to the sidewall portion, and gradually decreased from the sidewall portion to the bead portion. The inner liner layer thickness Ta in the region A corresponding to the buttress portion in the state filled with, the inner liner layer thickness Tb in the region B corresponding to the sidewall portion, and the inner liner in the region C corresponding to the bead portion. Since the layer thickness Tc is specified on the basis of the thickness T of the inner liner layer in the region corresponding to the tread portion, the side of the B region having the largest air permeation amount and the large bending deformation is centered. Durability is improved while efficiently suppressing air permeation throughout the wall. Can. Further, since the increase in the thickness of the inner liner layer is limited to the tire side portion only, and the increase in the thickness in each region is suppressed as much as possible, there is almost no increase in the weight of the tire.

  Moreover, according to the manufacturing method of this invention, the pneumatic tire mentioned above can be manufactured efficiently, without using a special material or adding a complicated process.

  FIG. 1 is a half sectional view showing a state in which a pneumatic tire according to an embodiment of the present invention is assembled with a rim and then filled with a normal internal pressure. FIG. 2 is an explanatory view showing only the inner liner layer taken out from the tire of FIG. FIG. 3 is an explanatory view corresponding to FIG. 2 showing the manufacturing process of the tire of FIG.

  In FIG. 1, a pneumatic tire 1 includes a plurality of (two layers in the figure) belts in which a carcass layer 3 is mounted on a pair of left and right bead portions 2 and 2 and cords are crossed between the outer peripheral sides of the carcass layer 3. Layers 4 and 5 are disposed, and an inner liner layer 6 for preventing air permeation is provided on the inner wall surface of the tire from the tread portion 7 to the bead portion 2 through the right and left buttress portions 8 and the sidewall portions 9. It is arranged. In the figure, 7 is a tread portion, 8 is a buttress portion, 9 is a sidewall portion, 10 is a bead core, and 11 is a rim.

In the pneumatic tire 1 of the present invention, the thickness of the inner liner layer 6 is gradually increased from the buttress portion 8 to the sidewall portion 9 and gradually decreased from the sidewall portion 9 to the bead portion 2. Further, as shown in FIGS. 1 and 2, the thickness T of the inner liner layer 6 in the region corresponding to the tread portion 7 and the outer peripheral surface of the tread portion 7 in a state filled with the normal internal pressure are directed inward in the tire radial direction. The thickness Ta of the inner liner layer 6 in the region A corresponding to the buttress portion 8 corresponding to 30% or less (15 to 30% in the figure) of the tire cross-section height SH and 45 to 55% of the tire cross-section height SH. The thickness Tb of the inner liner layer 6 in the region B corresponding to the sidewall portion 9 corresponding to the width of the inner liner layer 6 in the region C corresponding to the bead portion 2 corresponding to 80 to 90% of the tire cross-section height SH. The relationship between the thickness Tc is as follows.
Ta = (1.1-1.3) T
Tb = (1.4 to 1.7) T
Tc = (1.1 to 1.3) T

  Thereby, the durability can be improved while efficiently suppressing the air permeation amount over the entire sidewall portion 9 with the B region having the largest air permeation amount and undergoing a large bending deformation as a center. Further, since the increase in the thickness of the inner liner layer 6 is limited to only the tire side portion and the increase in the thickness in each region is suppressed as much as possible, there is almost no increase in the weight of the tire.

  In addition, the thickness T of the inner liner layer 6 in the region corresponding to the tread portion 7 described above refers to the thickness of the inner liner layer 6 inside the tread portion 7, and the thickness of the inner liner layer 6 varies. Means the average thickness of the maximum thickness and the minimum thickness.

  The thickness Tb of the inner liner layer 6 in the region B described above may be maximized at a point Q corresponding to the tire maximum width position P. That is, the thickness Tb of the inner liner layer 6 in the region B of the pneumatic tire 1 of the present invention is preferably formed so as to gradually decrease toward the buttress portion 8 side or the bead 2 portion side with the point Q as a boundary.

  The tire maximum width position P described above refers to the outermost position in the tire width direction formed by the outline of the sidewall portion 9 when the tire is mounted on an applicable rim and filled with a prescribed air pressure. The tire maximum width refers to a linear distance connecting the outer walls of the left and right sidewall portions 9 and 9 excluding a protect bar and characters / patterns formed on the side surface of the tire.

  Further, in the present invention, the above-described A region is 30% or less of the tire cross-section height SH from the outer peripheral surface of the tread portion 7 toward the inner side in the tire radial direction, but the lower limit (the outer end in the tire radial direction of the A region). 1 is set to a point R corresponding to the maximum tire width on the inner surface of the tread portion 7 as shown in FIG. 1, and the lower limit is preferably set to 15%. In other words, this lower limit value varies depending on the thickness of the tread portion 7, and in the case of a tire in which the thickness of the tread portion 7 is set large, the lower limit value is set to a value exceeding 15%. There is.

In the present invention, butyl rubber is preferably used for the inner liner layer 6. Examples of the butyl rubber include butyl rubber (IIR) and halogenated butyl rubber. The inner liner layer 6 is preferably made of a material having an air permeability of (4.5 to 5.5) × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg.

  In the above-described embodiment, the case where only the butyl rubber is used for the inner liner layer 6 is described. However, in the pneumatic tire 1 of the present invention, in order to further suppress the air permeation amount from the tire side portion, FIG. 3, the inner liner layer 6 is composed of a butyl rubber layer having a thickness T and a thermoplastic resin or thermoplastic elastomer layer 6 a having a low thickness and a low air permeability. The plastic resin or the thermoplastic elastomer layer 6a can be disposed by adhering to the inner surface of the tire of the butyl rubber layer in the direction of the arrow. Even in this case, it is necessary to adjust the total thicknesses Ta, Tb, and Tc of the inner liner layer 6 in each region so as to satisfy the relational expression described above.

As the thermoplastic resin or the thermoplastic elastomer layer 6a, a material having an air permeability of (1.5 to 3.0) × 10 ⁻¹¹ cc · cm / cm ² · sec · cmHg may be used.

  Examples of the thermoplastic resin include polyamide resins, polyester resins, polynitrile resins, poly (meth) acrylate resins, polyvinyl resins, cellulose resins, fluorine resins, imide resins, and the like.

  The thermoplastic elastomer is composed of the above-described thermoplastic resin and elastomer, and the composition ratio of the thermoplastic resin and the elastomer is 10/90 to 90/10 (weight ratio), preferably 20/80 to 85/15. Good. Examples of the elastomer constituting the thermoplastic elastomer include diene rubber and hydrogenated products thereof, olefin rubber, butyl rubber, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber, ionomer, halogen-containing Examples thereof include rubber, silicone rubber, sulfur-containing rubber, and fluorine rubber.

  In the embodiment described above, the case where the pneumatic tire 1 includes one carcass layer 3 and two belt layers 4 and 5 is illustrated as FIG. 1, but the structure of the pneumatic tire 1 of the present invention is the same. It is not limited to.

  The inner liner layer 6 of the pneumatic tire 1 of the present invention is required to have a high level of air permeation resistance. Therefore, the present invention is preferably applied to an ultra-flat tire having a flatness ratio of 40% or less at which the inner liner layer 6 is likely to deteriorate early due to repeated bending of the sidewall portion 9 during traveling.

  Although the manufacturing method of the pneumatic tire of this invention is not specifically limited, The following three methods can be mentioned as a preferable method.

  In the first manufacturing method, a non-vulcanized tire is molded by internally attaching a butyl rubber having a thickness adjusted as shown in FIG. 2 to the inner surface of the tread portion 7, and the unvulcanized tire is molded into a mold. It is done by vulcanizing in the inside.

  Further, the second manufacturing method is similar to a normal general manufacturing method, in which a butyl rubber having a uniform thickness is attached to the inner surface of the tread portion 7 to form an unvulcanized tire, After the unvulcanized tire is vulcanized in the mold, a vulcanized butyl rubber sheet 6b which is separately molded and vulcanized is pasted in the direction of the arrow on the inner surface of the side part of the vulcanized tire as shown in FIG. It is done by attaching. In this case, it is necessary to adjust the total thicknesses Ta, Tb, and Tc of the inner liner layer 6 in each region so as to satisfy the relational expression described above. Further, the butyl rubber sheet that is internally attached in the molding stage and the vulcanized butyl rubber sheet 6b that is attached to the vulcanized tire are preferably the same type of rubber, but different types of rubber. There may be.

  Further, in the third manufacturing method, similarly to the second manufacturing method, a butyl rubber having a uniform thickness is applied on the inner surface of the tread portion 7 to form an unvulcanized tire, After the vulcanized tire is vulcanized in the mold, a resin sheet 6c made of a thermoplastic resin or a thermoplastic elastomer is stuck in the direction of the arrow on the inner surface of the side part of the vulcanized tire as shown in FIG. Is done by. Even in this case, it is necessary to adjust the total thicknesses Ta, Tb, and Tc of the inner liner layer 6 in each region so as to satisfy the relational expression described above.

  As described above, in the pneumatic tire 1 and the manufacturing method thereof according to the present invention, the thickness of the inner liner layer 6 attached to the inner surface of the tire is gradually increased from the buttress portion 8 to the sidewall portion 9, so that the sidewall portion 9 Gradually from the bead portion 2 to the bead portion 2, the thickness Ta of the inner liner layer 6 in the region A corresponding to the buttress portion 8, and the thickness Tb of the inner liner layer 6 in the region B corresponding to the sidewall portion 9, By specifying the thickness Tc of the inner liner layer 6 in the region C corresponding to the bead portion 2 in relation to the thickness T of the inner liner layer 6 in the region corresponding to the tread portion 7, the weight of the tire is increased. The tire as a whole, centering on the B region that has the largest amount of air permeation and is subject to large bending deformation And it improves the durability while improving air permeation performance can be preferably applied to the super flat tire to easily oblateness inner liner layer is degraded 40% or less during running of the tire.

  The tire size is 245 / 35R20, the tire structure is shown in FIG. 1, and the conventional tire (conventional example) in which the thickness of the inner liner layer is uniform and the thickness of the inner liner layer in each region are different as shown in Table 1. Ten tires of the present invention (Examples 1 and 2) were manufactured.

  These three types of pneumatic tires were evaluated for air permeation resistance and durability by the following test methods, and the results are also shown in Table 1 using an index with the conventional tire as 100. It shows that it is excellent, so that this figure is large.

(Air permeability resistance)
Each tire is mounted on a rim (size: 20 × 8.5J), filled with air pressure of 230 kPa, and measured for air pressure after being left for 60 days in an atmosphere of normal temperature and 1 atm. The permeability was evaluated.

〔durability〕
Each tire is mounted on a rim (size: 20 x 8.5 J), filled with air pressure of 280 kPa, using an indoor drum tester (drum diameter: 1707 mm), traveling speed of 81 km / h, and load load specified by JATMA As the 88% of the maximum load capacity, the load load was increased by 13% every 2 hours, the travel distance until the failure occurred was measured, and the average value of the results was evaluated as the durability.

  From the results shown in Table 1, it can be seen that the tire of the present invention improves the air permeation resistance and at the same time the durability as compared with the conventional tire.

FIG. 3 is a half cross-sectional view showing a state in which a normal internal pressure is filled after a pneumatic tire according to an embodiment of the present invention is assembled with a rim. It is explanatory drawing which takes out and shows an inner liner layer from the tire of FIG. It is explanatory drawing equivalent to FIG. 2 which shows the manufacturing process of the tire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead part 6 Inner liner layer 6a Thermoplastic resin or thermoplastic elastomer layer 6b Butyl rubber sheet 6c Resin sheet | seat which consists of a thermoplastic resin or a thermoplastic elastomer 7 Tread part 8 Buttress part 9 Side wall part A A area | region BB area CC area SH Tire cross-section height

Claims (10)

In a pneumatic tire in which an inner liner layer for preventing air permeation is applied over the entire inner area of the tire from the tread portion to the bead portion through the left and right buttress portions and sidewall portions,
While gradually increasing the thickness of the inner liner layer from the buttress portion to the sidewall portion, and gradually decreasing from the sidewall portion to the bead portion,
The inner liner layer thickness T in the region corresponding to the tread portion and the tire cross-section height corresponding to 30% or less of the tire cross-section height from the outer peripheral surface of the tread portion to the inside in the tire radial direction in a state where normal internal pressure is filled. The inner liner layer thickness Ta in the A region corresponding to the buttress portion, the inner liner layer thickness Tb in the B region corresponding to the sidewall portion corresponding to 45 to 55% of the tire sectional height, and the tire cross section A pneumatic tire in which the relationship with the thickness Tc of the inner liner layer in the C region corresponding to the bead portion corresponding to 80 to 90% of the height is as follows.
Ta = (1.1-1.3) T
Tb = (1.4 to 1.7) T
Tc = (1.1 to 1.3) T   The pneumatic tire according to claim 1, wherein a thickness Tb of the inner liner layer is maximum at a tire maximum width position.   The pneumatic tire according to claim 1 or 2, wherein the inner liner layer is formed of butyl rubber. The pneumatic tire according to claim 3, wherein the inner liner layer has an air permeability of (4.5 to 5.5) x 10 ^-9 cc · cm / cm ² · sec · cmHg.   The inner liner layer is composed of a butyl rubber layer having a thickness T and a thermoplastic resin or thermoplastic elastomer layer having a remaining thickness, and the thermoplastic resin or thermoplastic elastomer layer is the butyl rubber. The pneumatic tire according to claim 1 or 2 arranged on the tire inner surface side of the layer. The air permeability of the butyl rubber layer is (4.5 to 5.5) × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg, and the air permeability of the thermoplastic resin or thermoplastic elastomer layer is The pneumatic tire according to claim 5, wherein the pneumatic tire is (1.5 to 3.0) × 10 ⁻¹¹ cc · cm / cm ² · sec · cmHg.   The pneumatic tire according to any one of claims 1 to 6, wherein the flatness is 40% or less.   The method for producing a pneumatic tire according to claim 3, wherein an unvulcanized tire is formed by attaching a butyl rubber sheet on the inner surface of the tread portion, and the unvulcanized tire is vulcanized in a mold.   A butyl rubber sheet having a uniform thickness is attached to the inner surface of the tread portion to form an unvulcanized tire, and the unvulcanized tire is vulcanized in a mold, and then the side of the vulcanized tire The method for producing a pneumatic tire according to claim 3, wherein a vulcanized butyl rubber sheet is attached to the inner surface of the part.   A butyl rubber sheet having a uniform thickness is attached to the inner surface of the tread portion to form an unvulcanized tire, and the unvulcanized tire is vulcanized in a mold, and then the side of the vulcanized tire The manufacturing method of the pneumatic tire of Claim 5 which affixes the resin sheet which consists of a thermoplastic resin or a thermoplastic elastomer on a part inner surface.

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