JP3588319B2 - Pneumatic tire - Google Patents

Description

【００４０】
【表２】

【００４１】
表１に示すように、実施例のタイヤでは、インナーライナレス構造において、そのメリットを生かしながら、耐久性を大巾に向上できるのが確認できる。
【００４２】
【発明の効果】
叙上の如く本発明は構成しているため、インナーライナレス構造のタイヤにおける、カーカスプライの重ね継ぎ部からのクラック等の発生を効果的に抑制でき、優れた耐久性や空気圧保持力を確保しつつ軽量化を達成しうる。
【図面の簡単な説明】
【図１】本発明の一実施例のタイヤの断面図である。
【図２】そのカーカスプライの２次継ぎを示す斜視図である。
【図３】（Ａ）は１次プライと２次プライとを説明する線図、（Ｂ）はカーカスプライの１次継ぎ及び２次継ぎを説明する周方向の略断面図である。
【図４】カーカスプライのトッピングゴムを説明する断面図である。
【図５】（Ａ）、（Ｂ）は、１次継ぎ及び２次継ぎを拡大して示す断面図である。
【図６】１次継ぎの他の例を示す断面図である。
【図７】（Ａ）、（Ｂ）は、カーカスプライの形成過程を説明する線図である。
【図８】従来の問題点を説明するカーカスプライの重ね継ぎ部の断面図である。
【符号の説明】
５ ビードコア
９ カーカスプライ
９Ａ 最内側のカーカスプライ
１０ カーカスコード
１１ コード配列体
１２ トッピングゴム
１２ｉ 内側部分
１２ｏ 外側部分
１３ 低空気透過性ゴム組成物
２０、２１ 重ね継ぎ部
２２、２３ ゴムストリップ層
Ｄ １次プライ
Ｆ ２次プライ
Ｊ１ １次継ぎ
Ｊ２ ２次継ぎ
Ｈ タイヤ内腔
ＨＳ タイヤ内腔面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire that achieves weight reduction while maintaining durability by eliminating a conventional inner liner by providing the innermost carcass ply with a pneumatic holding force.
[0002]
[Prior art]
In a tubeless pneumatic tire, an inner liner made of a low-air-permeability rubber composition is usually adhered to the inside of a carcass in order to keep air under internal pressure airtight. However, even with such tires, further reduction in weight has been demanded in response to recent demands for low fuel consumption.
[0003]
For this purpose, as shown in, for example, JP-A-6-156007 and JP-A-8-113007, a topping rubber of the innermost carcass ply is formed from the low air-permeable rubber composition, and There has been proposed a tire having an inner linerless structure in which the inner liner is eliminated by providing an air holding force.
[0004]
On the other hand, as shown in FIG. 7A, a carcass ply a is a long primary ply formed by covering a cord array b in which carcass cords are arranged in parallel in a longitudinal direction with a topping rubber c. d is used as a raw material. Specifically, this primary ply d is cut at a desired angle α (for example, about 75 to 90 ° in the case of a radial tire) with respect to the length direction and at a length La corresponding to the width of the carcass ply a. On the other hand, the end portions de on the non-cutting side of each cut piece d1 are sequentially connected (primary joint j1) to form a long carcass cord arranged at the angle α with respect to the longitudinal direction. The secondary ply f is formed. Then, as shown in FIG. 7B, the carcass ply f is cut by cutting the secondary ply f at one circumferential length and connecting both ends fe and fe in the circumferential direction (secondary joint j2). a is formed.
[0005]
At this time, as shown in FIG. 8, the primary joint j1 and the secondary joint j2 are usually overlapped with each other by overlapping and crimping between the ends de, de and between the ends fe, fe. A portion g is formed.
[0006]
[Problems to be solved by the invention]
Accordingly, in the above-described tire having the inner linerless structure, the joining line g1 of the lap joint g is exposed on the tire cavity surface. As a result, in the case of insufficient pressure bonding, poor rubber flow during vulcanization, or the like, cracks tend to occur starting from the joining line g1, and there is a problem that air pressure retention and durability are significantly reduced. In particular, since the secondary joint j2 is performed on the forming drum, insufficient bonding (insufficient bonding) is likely to occur, and this tendency is increased.
[0007]
Therefore, the present invention is based on the fact that a thin band-shaped rubber strip layer covering at least a lap joint formed by a secondary joint is disposed on the inner cavity surface of an inner linerless tire, and the joint line is used as a starting point. It is an object of the present invention to provide a pneumatic tire capable of effectively suppressing the occurrence of cracks and the like, and achieving weight reduction while ensuring excellent durability and pneumatic pressure holding force.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of the pneumatic tire according to claim 1 of the present application is to obliquely cut a primary ply obtained by covering a cord array in which carcass cords are aligned in parallel with topping rubber and to perform primary joining. One or more carcass plies bridged between bead cores around the tire lumen by making the secondary ply one circumference and using a secondary splice at both ends in the circumferential direction using the secondary ply formed by Form
And the innermost carcass ply forms a tire lumen surface by the inner portion of the topping rubber facing the tire lumen side between the bead cores,
The inner portion of the topping rubber of the innermost carcass ply contains 50 to 90% by weight of a diene rubber and 10 to 50% by weight of a halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer. Comprising a low air permeable rubber composition, and the outer portion comprises a non-low air permeable rubber composition,
A thickness of 0.1 to 0.5 mm extending in the direction between the bead cores, covering a joining line on the tire lumen surface formed by a lap joint formed by at least the secondary splicing on the tire lumen surface. And a band-shaped rubber strip layer having a width of 5 to 80 mm.
[0009]
According to a second aspect of the present invention, the rubber strip layer is made of a non-low air permeable rubber composition containing more than 90% by weight of a diene rubber as a rubber substrate .
[0010]
Further, in the invention according to claim 3, the rubber strip layer includes a rubber strip layer covering a lap joint formed by the primary joint.
[0011]
In the invention according to claim 4, the topmost rubber of the innermost carcass ply has a rubber thickness from the inner edge of the carcass cord to the inner surface of the tire cavity of 0.2 to 0.7 mm.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples.
FIG. 1 shows a meridional section when the pneumatic tire of the present invention is a passenger car tire.
[0013]
In the figure, a pneumatic tire 1 has a tread portion 2, a sidewall portion 3 extending inward in the tire radial direction from both ends thereof, and a bead portion which is located at an inner end of each sidewall portion 3 and in which a bead core 5 is embedded. 4 and so on. Further, a carcass 6 is bridged between the bead cores 5 and 5 on the tire 1, and a tough belt layer 7 is disposed radially outside the carcass 6 and inside the tread portion 2.
[0014]
In the case where the belt layer 7 is formed of two or more belt plies 7A and 7B in which high elastic belt cords are arranged at an angle of, for example, 10 ° to 35 ° with respect to the tire circumferential direction, in this example, two belt plies 7A and 7B. Is exemplified. The belt plies 7A and 7B are arranged in different directions so that the belt cords intersect each other between the plies, thereby increasing the belt rigidity by a triangle structure of the cords, and having a tag effect with substantially the entire width of the tread portion 2. And reinforce.
[0015]
2, the carcass 6 is formed from one or more carcass plies 9 in which carcass cords 10 are arranged at an angle α of, for example, 75 to 90 degrees with respect to the tire circumferential direction, in this example, one carcass ply 9 as shown in FIG. You. The carcass ply 9 includes a ply body 6A extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3, and in the present example, the ply body portion 6A is connected to the ply body portion 6A and the bead core 5 is rotated around the tire. It has a so-called 1-0 structure having a ply turnup portion 6B that is turned inward from the outside in the axial direction. In addition, what is called a 2-0 structure using two carcass plies 9 and 9 or what is called a 1-1 structure can also be suitably employ | adopted by request.
[0016]
Here, as shown in FIG. 3A, the carcass ply 9 is a long primary member formed by covering a cord array 11 in which carcass cords 10 are aligned in parallel along a longitudinal direction with a topping rubber 12. The ply D is formed as a raw material. The primary ply D is cut into cut pieces D1... At the angle α with respect to the length direction and at a length La corresponding to the width of the carcass ply 9, and thereafter, the non-cut side of each cut piece D1 is cut. Are sequentially connected (primary joint J1) to form a long secondary ply F in which carcass cords are arranged at the angle α with respect to the longitudinal direction. The carcass ply 9 is formed by cutting the secondary ply F at one circumferential length and connecting both ends Fe and Fe in the circumferential direction (secondary joining J2).
[0017]
Accordingly, the carcass ply 9 has a plurality of primary joints J1 and one secondary joint J2, as shown in FIG. 3B schematically showing a circumferential cross section along the tire equator C. Continuous.
[0018]
In the present embodiment, a conventional inner liner is eliminated by applying an air pressure holding force to the innermost carcass ply 9A. That is, the innermost carcass ply 9A forms the tire cavity surface HS by the inner portion 12i of the topping rubber 12 facing the tire cavity H between the bead cores 5 and 5.
[0019]
As shown in FIG. 4, at least the inner portion of the inner portion 12i of the topping rubber 12 of the innermost carcass ply 9A and the opposite outer portion 12o are provided to impart the air pressure holding force. 12i is formed of the low air permeable rubber composition 13.
[0020]
Na us, the outer portion 12o, and using a non-low air permeability rubber composition 14 where the diene rubber used more than 90% by weight rubber substrate. As the diene rubber, natural rubber, butadiene rubber, styrene / butadiene rubber, isoprene rubber, chloroprene rubber, acrylonitrile butadiene rubber, or the like can be used alone or in combination.
[0021]
The low air permeable rubber composition 13 comprises, as a rubber base material, 50 to 90% by weight of the diene rubber and 10 to 50% by weight of a halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer. And the one containing This achieves both low air permeability and adhesion to other rubber members and the carcass cord 10. From the viewpoint of adhesiveness, the content of the diene rubber is set to 65% by weight or more and the content of the halogenated butyl rubber or the halide of isobutylene / paramethylstyrene copolymer is 35% by weight or less within the above range. It is preferred that
[0022]
As the halogenated butyl rubber, chlorinated butyl rubber and brominated butyl rubber can be used.
[0023]
The isobutylene / paramethylstyrene copolymer halide is not particularly limited, but from the viewpoint of adhesiveness, the isobutylene content is 89 to 97% by weight, preferably 89 to 95% by weight, particularly preferably It is preferably from 89 to 93% by weight. Examples of commercially available halides of isobutylene / paramethylstyrene copolymer include EXXPRO90-10, EXXPRO89-4, and EXXPRO93-5 manufactured by Exxon Chemical Co., Ltd.
[0024]
In this example, in order to ensure higher adhesiveness in the low air-permeable rubber composition 13, a tackifier is added and the use of a plasticizer is excluded. Examples of the tackifier include a coumarone resin, a phenol resin, a terpene resin, a petroleum hydrocarbon resin, a rosin derivative and the like, and 1 to 10 parts by weight, and further 3 to 10 parts by weight, based on 100% by weight of the rubber base material. %, More preferably 3 to 8% by weight, from the viewpoint of adhesiveness. Also, as the plasticizer, mineral oil-based softeners such as mineral oil and aroma oil, plant-based softeners, phthalic acid derivatives and the like are known, and are usually added for improving the processability and flexibility of rubber. However, in this example, it is not used because it tends to reduce the adhesiveness.
[0025]
Next, as shown in FIG. 5 (A), the secondary joint J2 is performed by overlapping the ends Fe and Fe with each other and press-bonding, thereby forming the overlapped portion 20. In this example, the primary joint J1 (shown in FIG. 5B) is similarly formed by overlapping and crimping the ends De and De, thereby forming the overlapped portion 21. You.
[0026]
In the lap joints 20, 21, the joint lines 20A, 21A are exposed on the tire cavity surface HS by employing an inner linerless structure. As a result, cracks tend to occur starting from the joining line g1 due to insufficient pressure bonding, insufficient rubber flow during vulcanization, or infiltration of a release agent. In particular, since the secondary joint J2 is performed on the forming drum, the joining accuracy is inferior, and the bonding tends to be insufficient.
[0027]
Therefore, in this embodiment, a rubber strip layer 22 extending in the direction between the bead cores 5 and 5 is provided on the tire cavity surface HS so as to cover at least the joining line 20A of the lap joint 20 formed by the secondary joint J2. are doing. In this example, similarly, a case is shown in which a rubber strip layer 23 covering the joining line 21A of the lap joint 21 formed by the primary joint J1 is similarly provided.
[0028]
The rubber strip layers 22 and 23 each have a thin band shape having a thickness T1 of 0.1 to 0.5 mm and a width W1 of 5 to 80 mm, and cover and protect the exposed portions of the joining lines 20A and 21A. Effectively suppresses the occurrence of cracks. When the thickness T1 is less than 0.1 mm and the width W1 is less than 5 mm, the suppressing effect is not sufficiently exhibited. Conversely, when the thickness T1 is greater than 0.5 mm and the width W1 is greater than 80 mm, the weight is reduced. It increases unnecessarily, not only losing the advantage of weight reduction by the inner linerless structure, but also adversely affecting tire uniformity. For this reason, the width W1 is more preferably about 25 to 50 mm.
[0029]
The rubber strip layers 22 and 23 are preferably formed of a low air permeable rubber composition from the viewpoint of air leak resistance. At this time, the low air permeable rubber composition having the same or the same composition as the inner portion 12i is used. Alternatively, it may be a low air permeable rubber composition of a different composition. Here, the “homogeneous composition” means the same kind of rubber constituting the rubber base material and the compounding ratio thereof is different, and the “heterogeneous composition” means the type of rubber constituting the rubber base material It means something different in itself. Note that the rubber strip layers 22 and 23 can also be formed of a non-low air permeable rubber composition.
[0030]
In the innermost carcass ply 9A, the rubber thickness T2 (coating thickness) from the inner edge of the carcass cord 10 to the tire cavity surface HS is preferably 0.2 to 0.7 mm, and less than 0.2 mm. In this case, the air leak resistance is greatly reduced, and it is difficult to sufficiently secure the air pressure holding force. On the other hand, if the thickness exceeds 0.7 mm, the weight is unnecessarily increased, and the advantage of weight reduction by the inner linerless structure is impaired.
[0031]
Further, in this example, as described above, the case where the non-low air permeability rubber composition 14 is used for the outer portion 12o is illustrated, but the same or similar low air permeability rubber composition as the inner portion 12i is used. It may be formed of a material or a low-air-permeable rubber composition of a different composition.
[0032]
Note Because the outer portion 12o is formed in a non-low air permeability rubber composition 14, the boundary line K between the inner portion 12i and the outer part 12o is outward from the inner edge of the carcass cord 10 as in the present example be positioned is not preferable from the viewpoint of the light weight and resistance to air leakage performance.
[0033]
In the case of the primary joint J1, for example, as shown in FIG. 6, the ends De, De may be joined to each other in a zipper shape with their end faces attached to each other. Preferably, it is coated with a layer 23.
[0034]
As described above, particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.
[0035]
【Example】
A tire having the structure shown in FIG. 1 and having a tire size of 195 / 65R15 was prototyped based on the specifications in Table 1, and the tire weight, air leak resistance (air pressure retention), and durability of each test tire were measured. Table 1 shows the results of comparison with conventional tires. Table 2 shows the composition of the rubber composition used in Table 1.
[0036]
(1) Tire weight:
The weight per tire is measured, and is indicated by an index with the conventional tire being 100. Smaller values are lighter.
[0037]
(2) Air leak resistance (air pressure retention):
After the test tire is mounted on a rim (15 × 6JJ) and filled with an internal pressure (300 kPa), the internal pressure drop rate when allowed to stand naturally for 90 days is indicated by an index with the conventional tire being 100. The smaller the value, the better.
[0038]
(3) Durability The test tire is mounted on a rim (15 × 6JJ), filled with an internal pressure (190 kPa), and run on a drum under a load (6.96 kN) and a speed (70 km / h). The running distance until the outer surface was damaged was indicated by an index when the conventional tire was set to 100. The larger the index, the better.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
As shown in Table 1, it can be confirmed that in the tire of the example, the durability can be greatly improved while taking advantage of the inner linerless structure.
[0042]
【The invention's effect】
As described above, since the present invention is configured, in an inner linerless tire, occurrence of cracks and the like from a lap joint portion of a carcass ply can be effectively suppressed, and excellent durability and air pressure holding force are secured. While achieving weight reduction.
[Brief description of the drawings]
FIG. 1 is a sectional view of a tire according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a secondary joint of the carcass ply.
FIG. 3A is a diagram illustrating a primary ply and a secondary ply, and FIG. 3B is a schematic cross-sectional view in the circumferential direction illustrating a primary splice and a secondary splice of a carcass ply.
FIG. 4 is a cross-sectional view illustrating a topping rubber of a carcass ply.
FIGS. 5A and 5B are cross-sectional views showing a primary joint and a secondary joint in an enlarged manner.
FIG. 6 is a sectional view showing another example of the primary joint.
FIGS. 7A and 7B are diagrams illustrating a process of forming a carcass ply. FIGS.
FIG. 8 is a sectional view of a lap joint portion of a carcass ply for explaining a conventional problem.
[Explanation of symbols]
5 Bead core 9 Carcass ply 9A Innermost carcass ply 10 Carcass cord 11 Cord array 12 Topping rubber 12i Inner portion 12o Outer portion 13 Low air permeable rubber composition 20, 21 Spliced portion 22, 23 Rubber strip layer D Primary Ply F Secondary ply J1 Primary joint J2 Secondary joint H Tire bore HS Tire bore

Claims (4)

Using a secondary ply formed by diagonally cutting and priming a primary ply in which a carcass cord is arranged in parallel and arranged with a topping rubber, the secondary ply has one circumference. Secondary joining at both ends in the circumferential direction forms one or more carcass plies that are bridged between the bead cores around the tire lumen,
And the innermost carcass ply forms a tire lumen surface by the inner portion of the topping rubber facing the tire lumen side between the bead cores,
The inner portion of the topping rubber of the innermost carcass ply contains 50 to 90% by weight of a diene rubber and 10 to 50% by weight of a halogenated butyl rubber or a halide of isobutylene / paramethylstyrene copolymer. Comprising a low air permeable rubber composition, and the outer portion comprises a non-low air permeable rubber composition,
A thickness of 0.1 to 0.5 mm extending in the direction between the bead cores, covering a joining line on the tire lumen surface formed by a lap joint formed by at least the secondary splicing on the tire lumen surface. A pneumatic tire comprising a band-shaped rubber strip layer having a width of 5 to 80 mm. The pneumatic tire according to claim 1, wherein the rubber strip layer is made of a non-low air-permeable rubber composition containing a diene-based rubber as a rubber base material in an amount of more than 90% by weight. The pneumatic tire according to claim 1, wherein the rubber strip layer includes a rubber strip layer that covers a lap joint formed by the primary joint. The topping rubber of the innermost carcass ply has a rubber thickness from the inner edge of the carcass cord to the inner surface of the tire of 0.2 to 0.7 mm. Pneumatic tires.

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