JP4673486B2 - Pneumatic tire manufacturing method and pneumatic tire manufactured thereby - Google Patents

Description

【００４０】
実施例の空気入りタイヤは、カーボン溶液の塗布により、カーボンの純度が高い層を形成しているため、このカーボン層の厚さＴが０．００２ｍｍと非常に薄い場合にも、タイヤの電気抵抗を充分に減じることができる。
【００４１】
【発明の効果】
本発明は叙上の如く構成しているため、導電性のカーボン層をタイヤ周方向にのびることなく簡易に形成でき、偏摩耗による見映えや走行性能の低下を抑制しうるとともに、ゴム押出機のヘッドをそのまま使用でき、装置コストや設備コストの上昇をも防止しうる。
【００４２】
又カーボン層は、カーボンの純度が高いため、タイヤの電気抵抗を充分に低く維持しながら、その層厚さを大巾に減じることができ、偏摩耗自体の抑制、及び走行性能の低下をさらに行うことができる。
【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】トレッド部のタイヤ赤道に沿う周方向断面図である。
【図３】（Ａ）は、生タイヤのシェーピング工程を示す略図、（Ｂ）はトレッドリング形成工程を示す線図である。
【図４】トレッドゴムへのカーボン溶液の塗布を示す断面図である。
【図５】タイヤの電気抵抗の測定方法を説明する線図である。
【図６】従来技術を説明するタイヤの断面図である。
【符号の説明】
２Ｇ トレッドゴム
２Ｒ トレッドリング
２０ カーボン層
２１ カーボン溶液
Ｅ１ 始端部
Ｅ２ 終端部
ＥＳ 接合面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a pneumatic tire capable of effectively discharging static electricity generated in a vehicle to a road surface even when a rubber material containing silica, for example, is used for tread rubber, and a pneumatic tire manufactured thereby. About.
[0002]
[Prior art]
The development of fuel-efficient tires with reduced rolling resistance in response to the recent reduction in fuel consumption of automobiles is underway. To that end, it is proposed to replace carbon (carbon black) with silica as a filler for tread rubber. Has been. Silica, unlike carbon, has a strong chemical bond with rubber via a binder, so tread rubber reinforced with silica reduces rolling resistance, makes the rubber easy to move and has high adhesive strength. It has the advantage of excellent performance.
[0003]
However, a decrease in the amount of carbon added causes an increase in the electrical resistance of the tire, and causes a number of electrical malfunctions such as causing radio interference such as radio noise due to accumulation of static electricity in the vehicle.
[0004]
In order to improve the electric resistance of such a fuel-efficient tire, for example, Japanese Patent Laid-Open No. 2000-1610 discloses a tread rubber A made of conductive material mainly composed of carbon as shown in FIG. A through terminal which is composed of a base rubber body a and an insulating cap rubber body b mainly composed of silica, and a part of the base rubber body a is raised like a rib extending in the circumferential direction and exposed on the tread surface. What forms part a1 is proposed.
[0005]
[Problems to be solved by the invention]
However, since the rubber properties of the penetrating terminal portion a1 and the cap rubber body b are different, uneven wear is likely to occur, and this uneven wear is continuously formed in the circumferential direction. There is a problem that the decline of In addition, since the through terminal portion a1 is formed, the structure of the head of the rubber extruder becomes complicated, leading to an increase in the cost of the apparatus.
[0006]
In the case of a pneumatic tire, when the green tire is formed, a tread rubber is wound on a cylindrical drum in the circumferential direction, and the start end portion and the end end portion are bonded to each other at the joining surface to thereby form a tread portion. An annular tread ring is formed.
[0007]
Therefore, the present invention has been made paying attention to the process of forming the tread ring, and is based on applying a carbon solution to the joint surface in advance prior to the bonding of the tread rubber. Can be easily formed without extending in the tire circumferential direction, it can suppress the appearance and deterioration of ground contact due to uneven wear, and the head of the rubber extruder can be used as it is, preventing an increase in equipment cost and equipment cost An object of the present invention is to provide a method for producing a pneumatic tire and a pneumatic tire produced thereby.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention of claim 1 of the present application is that a tread ring is formed by winding a belt-shaped tread rubber on a cylindrical drum and bonding the winding start and end portions at the joining surface. A method for manufacturing a pneumatic tire including a tread ring forming step to be formed,
In the tread ring forming step, prior to the laminating, carbon is contained in a solvent (base material) at a ratio of 3% by weight to 30% by weight on at least one joint surface of the start end part or the end part of the tread rubber. A carbon layer is formed between the joint surfaces by applying a dissolved or dispersed carbon solution and then bonding them together.
[0009]
According to a second aspect of the present invention, the carbon solution is a low viscosity solution having a viscosity measured at 25 ° C. of 75 centipoise (cp) or less.
[0010]
In the invention of claim 3, the carbon solution is characterized in that the solvent is water, alcohol, or an organic solvent and does not contain a rubber component.
[0011]
According to a fourth aspect of the present invention, the carbon layer has a thickness after vulcanization of 1 to 80 μm, and an electrical resistance per 1 mm ^{2 of a} cross-sectional area of 10 ⁸ Ω · cm or less.
[0012]
A fifth aspect of the present invention is a pneumatic tire invention, which is manufactured by the manufacturing method according to any one of the first to fourth aspects.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a more specific embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a meridional sectional view of a pneumatic tire manufactured by using the manufacturing method of the present invention, and FIG. 2 is a circumferential sectional view of a tread portion along the tire equator.
[0014]
In FIG. 1, a pneumatic tire 1 includes a toroidal carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, the outer side of the carcass 6 in the tire radial direction, and the inside of the tread portion 2. In this example, the belt structure B having good conductivity is provided. In addition, in this example, the case where the pneumatic tire 1 is a radial tire for passenger cars is illustrated.
[0015]
The carcass 6 is formed of a single carcass ply 6A in this example, a main body portion 6a extending across the bead cores 5 and 5, a tire shaft extending around the bead core 5 and connected to both sides of the main body portion 6a. Folded portions 6b and 6b folded from the inner side to the outer side are provided. Further, a hard bead apex rubber 8 is disposed between the main body portion 6a and the folded portion 6b to reinforce the bead portion 4.
[0016]
The carcass ply 6A has, for example, a radial structure in which carcass cords are arranged at an angle of 75 to 90 degrees with respect to the tire equator C. In this example, a polyester cord is used as the carcass cord, but other nylon, rayon, Various organic fiber cords such as vinylon and aromatic polyamide, and steel cords can be used.
[0017]
The belt structure B is formed from a belt layer 7 including a steel cord in this example. The belt layer 7 is composed of two belt plies 7A and 7B in which both sides of steel cord arrays arranged substantially in parallel are covered with topping rubber. The steel cords are arranged at an angle of 15 to 40 degrees with respect to the tire equator C. The two belt plies 7A and 7B are arranged so as to overlap each other so that the steel cords intersect.
[0018]
The belt layer 7 is made of a rubber material in which the belt cord is made of steel cord, and the topping rubber contains carbon so that the volume specific electrical resistance value is less than 1 × 10 ⁸ (Ω · cm), for example. The belt layer 7 is given good conductivity. In addition to the steel cord, other conductive cords such as a carbon fiber cord can be used as required as the belt cord. The belt structure B may be provided with a band layer or the like outside the belt layer 7. The volume specific electrical resistance value of the rubber is indicated by a value measured using an ADVANTESTER 8340A electrical resistance measuring instrument for a rubber sample 15 cm square and 2 mm thick under the conditions of an applied voltage of 500 V, an air temperature of 25 ° C., and a humidity of 50%. ing.
[0019]
A tread rubber 2G is disposed outside the belt structure B in the tire radial direction. In this example, the tread rubber 2G is exemplified by a single-layer structure composed of a silica-containing rubber material 11 reinforced with silica.
[0020]
As described above, the tread rubber 2G is improved in wet grip performance and reduced in rolling resistance on a dry road surface by blending silica. The tread rubber 2G may have a two-layer structure in which, for example, a base layer made of a low heat-generating rubber material with reduced tangent loss is formed on the radially inner side of the silica-containing rubber material 11.
[0021]
In the silica-containing rubber material 11, for example, 30 to 100 parts by weight, preferably 40 to 70 parts by weight, and more preferably 40 to 60 parts by weight of silica are added to 100 parts by weight of the rubber base material. Thereby, the reduction of the rolling resistance and the improvement of the wet grip performance are compatible at a higher level.
[0022]
Examples of the rubber base material include natural rubber (NR), butadiene rubber (BR) which is a butadiene polymer, so-called emulsion polymerization styrene butadiene rubber (E-SBR), and solution polymerization styrene butadiene rubber (S). -SBR), synthetic polyisoprene rubber (IR) which is a polymer of isoprene, nitrile rubber (NBR) which is a copolymer of butadiene and acrylonitrile, chloroprene rubber (CR) which is a polymer of chloroprene, and the like. It is preferable to use a rubber obtained by blending one or more of these.
[0023]
The silica to be blended is not particularly limited, but shows colloidal characteristics with a nitrogen adsorption specific surface area (BET) in the range of 150 to 250 m ² / g and a dibutyl phthalate (DBP) oil absorption of 180 ml / 100 g or more. Is preferable from the viewpoints of reinforcing effect on rubber and rubber processability. As the silane coupling agent, bis (triethoxysilylpropyl) tetrasulfide and α-mercaptopropyltrimethoxysilane are suitable.
[0024]
In addition, carbon (carbon black) may be supplementarily blended in the silica blended rubber material 11 in order to impart other physical properties such as rubber elasticity, rubber hardness, low heat build-up, and the like. At this time, the amount of carbon to be added to the silica-blended rubber material 11 is 15 parts by weight or less, more preferably 10 parts by weight or less, more preferably 0 to 5 parts by weight with respect to 100 parts by weight of the rubber base material. Is desirable. When the blending amount of the carbon exceeds 15 parts by weight, it is difficult to obtain satisfactory rubber physical properties as the tread rubber 2G because the reduction effect of the rolling resistance due to silica is reduced and the rubber tends to be hard. On the other hand, if the amount of silica exceeds 100 parts by weight, it is difficult to add carbon to obtain the other physical properties of the rubber.
[0025]
And in the pneumatic tire 1 of this embodiment, in order to suppress the increase in the electrical resistance value of the tire by using the silica compound rubber material 11 for the tread rubber 2G and to smoothly discharge to the road surface, FIG. As shown, a thin carbon layer 20 is formed on the tread portion 2 so as to extend across the tread portion 2 in the tire axial direction and rise from the belt structure B to the tread surface.
[0026]
Moreover, the carbon layer 20 has a great feature in that it is formed by the carbon solution 21 applied to the tread rubber 2G in the tread ring forming step when forming the green tire.
[0027]
Specifically, in a pneumatic tire, when a green tire is formed, a carcass ply 6A wound in a cylindrical shape is bulged between bead cores 5 and 5 as schematically shown in FIG. A tread ring 2R including a belt structure B and a tread rubber 2G is attached to a central portion of the carcass ply 6A. Further, as shown in FIG. 3 (B), the tread ring 2R is formed on a cylindrical drum D via a belt structure B (not shown in FIG. 3 (B)) and a belt-like tread rubber 2G. Is formed by a tread ring forming process in which the start end E1 and the end E2 of the winding are bonded to each other at the joint surface ES.
[0028]
And in this embodiment, prior to this bonding, as shown in FIG. 4, a carbon solution 21 is applied to at least one joining surface ES of the start end E1 or the end E2 of the belt-shaped tread rubber 2G, Thereafter, the carbon layer 20 is formed between the bonding surfaces ES and ES by bonding.
[0029]
The application of the carbon solution 21 is preferably performed on both joint surfaces ES, particularly at one end (for example, the start end E1) beyond the joint surface ES to a part of the upper surface and the other end. In order to obtain reliable conductivity, it is preferable that the portion (for example, the end portion E2) is applied so as to protrude from the joint surface ES to a part of the lower surface. At this time, the protruding length L from the bonding surface ES is preferably about 5 to 80 mm from the viewpoint of bonding properties and conductivity.
[0030]
Next, the carbon solution 21 is obtained by dissolving or dispersing carbon in a solvent (base material). The carbon is contained in a ratio of 3 to 30% by weight with respect to the total weight of the carbon solution 21. Yes.
[0031]
Here, water, alcohol, or an organic solvent can be used as the solvent. In the case where the solvent is water or alcohol, the applied carbon solution 21 is once dried, and thereafter, the start end E1 and the end E2 are bonded.
[0032]
The carbon solution 21 does not contain rubber particles and is formed as a low viscosity solution having a viscosity at 25 ° C. of 75 centipoise (cp) or less.
[0033]
In such a carbon layer 20 formed by the carbon solution 21, since the purity of carbon is high, the electrical resistance is very low. For example, the electrical resistance per 1 mm ^{2 of} the cross-sectional area is suppressed to 10 ⁸ Ω · cm or less. Can do. Therefore, even when the thickness T of the carbon layer 20 after vulcanization is reduced to a range of 1 to 80 μm (0.001 mm to 0.08 mm), excellent conductivity can be exhibited.
[0034]
In addition, since the carbon layer 20 extends in the tire axial direction, even when uneven wear occurs, the appearance of the carbon layer 20 is less likely to deteriorate, and since the ground contact is instantaneous for each rotation of the tire, the influence on the tire running performance is affected. Can be suppressed. In particular, since the thickness T can be reduced to the above range, it is possible to further eliminate adverse effects on uneven wear and running performance.
[0035]
In the carbon solution 21, in order to improve adhesion, 0.1 to 1.5% by weight (carbon solution) of an adhesion-imparting material such as a thermoplastic phenol resin (manufactured by Sumitomo Durez; Sumilite Resin PR-19900) is used. For a total weight of 21).
[0036]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.
[0037]
【Example】
A pneumatic tire (size: 195 / 60R14) having the basic structure shown in FIGS. 1 and 2 was made with the specifications shown in Table 1, the electrical resistance of the sample tire was measured, and the results are shown in Table 1.
[0038]
(1) tire electrical resistance;
As shown in FIG. 5, on the steel plate 31 that is mounted in an insulated state with respect to the base plate 30, the tire 1 is grounded vertically in a loaded state, and between the rim J (6 × 14 ″) and the steel plate 31. The electrical resistance was measured under the conditions of an applied voltage of 1000 V, an air temperature of 25 ° C., a humidity of 50%, an internal pressure of 200 kpa, and a longitudinal load of 350 kgf.
[0039]
[Table 1]

[0040]
Since the pneumatic tire of the example forms a layer having a high carbon purity by application of the carbon solution, even when the thickness T of the carbon layer is as very thin as 0.002 mm, the electrical resistance of the tire Can be reduced sufficiently.
[0041]
【The invention's effect】
Since the present invention is configured as described above, the conductive carbon layer can be easily formed without extending in the tire circumferential direction, and appearance and running performance deterioration due to uneven wear can be suppressed. The head can be used as it is, and an increase in apparatus cost and equipment cost can be prevented.
[0042]
In addition, since the carbon layer has a high carbon purity, the thickness of the layer can be greatly reduced while maintaining the electrical resistance of the tire sufficiently low, further suppressing uneven wear and further reducing the running performance. It can be carried out.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire according to an embodiment of the present invention.
FIG. 2 is a circumferential cross-sectional view along the tire equator of a tread portion.
FIG. 3A is a schematic diagram showing a shaping process of a raw tire, and FIG. 3B is a diagram showing a tread ring forming process.
FIG. 4 is a cross-sectional view showing application of a carbon solution to tread rubber.
FIG. 5 is a diagram illustrating a method for measuring the electrical resistance of a tire.
FIG. 6 is a cross-sectional view of a tire for explaining a conventional technique.
[Explanation of symbols]
2G tread rubber 2R tread ring 20 carbon layer 21 carbon solution E1 start end E2 end end ES joint surface

Claims (5)

A method of manufacturing a pneumatic tire including a tread ring forming step of forming a tread ring by winding a belt-shaped tread rubber on a cylindrical drum and bonding a start end portion and a terminal end portion of the winding at a joining surface. And
In the tread ring forming step, prior to the bonding, carbon was dissolved or dispersed in a solvent at a ratio of 3 wt% to 30 wt% on at least one joint surface of the start end portion or the end portion of the tread rubber. A method for producing a pneumatic tire, wherein a carbon layer is formed between the joint surfaces by applying a carbon solution and then bonding the carbon solution. The method for producing a pneumatic tire according to claim 1, wherein the carbon solution is a low-viscosity solution having a viscosity measured at 25 ° C of 75 centipoise (cp) or less. The method for producing a pneumatic tire according to claim 1 or 2, wherein the carbon solution is water, alcohol, or an organic solvent and does not contain a rubber component. 4. The carbon layer according to claim 1, 2, or 3, wherein the carbon layer has a thickness after vulcanization of 1 to 80 [mu] m and an electric resistance of 10 < ⁸ > [Omega] .cm or less per 1 mm < ² > cross-sectional area. A method of manufacturing a pneumatic tire. A pneumatic tire manufactured by the manufacturing method according to claim 1.

Images