JP7256649B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

The present invention relates to a pneumatic tire and a manufacturing method thereof.

Static electricity charged in the vehicle is released to the road surface through the pneumatic tires. This prevents the charged static electricity from adversely affecting the functions of the electronic circuit components and the reception sensitivity of the radio. Therefore, pneumatic tires are required to have a certain degree of electrical conductivity. Therefore, it is necessary to construct a conductive path, especially from the rim to the ground plane.

In Patent Document 1, a first conductive portion extending in the tire circumferential direction at a portion of the rim cushion rubber layer that contacts the rim, and a splice portion in the tire circumferential direction of the side rubber layer and the rim cushion rubber layer extending in the tire radial direction. a second conductive portion extending in the tire circumferential direction on the inner peripheral surface side of the tread rubber layer; and a third conductive portion extending from the third conductive portion to the ground contact surface of the tread rubber layer in the tread rubber layer. A pneumatic tire with four conductive sections is disclosed. In the pneumatic tire, the conductive path from the rim to the ground surface is configured by the first to fourth conductive portions.

JP 2013-216115 A

By the way, as a method of manufacturing a pneumatic tire, there is known a ribbon construction method in which a rubber ribbon is helically wound around a drum to form an annular rubber member. Since the ribbon construction method can easily form tires of various shapes, it is highly versatile and is used in combination with various other construction methods.

Patent Literature 1 does not mention in detail how to ensure electrical conductivity in the ribbon construction method. Therefore, when using the ribbon construction method, it is necessary to devise ways to secure the conductive path.

An object of the present invention is to secure a conductive path from a bead portion to a shoulder portion while using a ribbon construction method in a pneumatic tire and a manufacturing method thereof.

A first aspect of the present invention is a tread portion, shoulder portions adjacent to the tread portion and arranged on both outer sides in the tire width direction, and ribbon-shaped non-conductive rubber adjacent to the shoulder portions. A sidewall portion formed of dual-side rubber partially covered with a coating material whose core material is a film-like conductive rubber; and a bead portion disposed adjacent to the sidewall portion. A conductive path is provided in which a member having elasticity is continuously formed from the bead portion to the shoulder portion. The coating material of the dual-side rubber overlaps to constitute the conductive path, and at least a part of the shoulder portion is a ribbon-shaped non-conductive rubber, and the core material is a film-shaped conductive rubber. In the shoulder portion, the dual cap rubber is spirally wound, and the covering material of the dual cap rubber adjacent in the tire meridian cross section overlaps and is partially exposed on the outer surface of the shoulder portion, and the covering material of the dual cap rubber of the shoulder portion and the covering material of the dual side rubber of the sidewall portion are in contact with each other, and the shoulder portion wherein said conductive path includes said dual cap rubber, and each of said coatings of said overlapping dual cap rubber is partially exposed on the outer surface of said shoulder portion. .

According to this configuration, even when the ribbon construction method is used, a conductive path from the bead portion to the shoulder portion via the sidewall portion can be secured. That is, a conductive path can be secured from the rim contacting the bead portion to the ground plane contacting the shoulder portion. In particular, the dual-side rubber covering material overlaps in the sidewall portion. Therefore, since the conductive members are continuous, a conductive path can be secured. Here, the term “conductivity” refers to a material property with a volume resistivity of less than 1.0×10 ⁸ (Ω·cm), and the term “non-conductivity” refers to a material property with a volume resistivity of less than 1.0×10 ⁹ (Ω·cm). ) refers to the above material properties. Also, the dual cap rubber can impart conductivity to the shoulder portion. In particular, since the covering material of the dual cap rubber is exposed on the outer surface of the shoulder portion, a conductive path to the ground plane can be secured. In addition, since the covering material of the dual cap rubber on the shoulder portion and the covering material of the dual side rubber on the sidewall portion are in contact with each other, a conductive path from the sidewall portion to the shoulder portion can be secured.

The covering material may cover at least the bottom surface portion of the core material, which is the surface on the sticking surface side, and two corner portions that are continuous with the bottom surface portion.

According to this configuration, when the dual-side rubber is spirally wound, the covering material that covers the bottom surface and the covering material that covers the corners of the adjacent dual-side rubbers come into contact with each other, so that a conductive path can be secured. .

The bead portion includes a conductive bead core and a conductive bead filler adjacent to the bead core, and the conductive path in the bead portion and the sidewall portion includes at least the bead core, the bead filler, and the dual Side rubber may be included.

According to this configuration, since the bead filler generally has conductivity, the conductive path can be configured including the bead filler.

The bead portion includes a conductive rubber chaser interposed between the bead filler and the dual-sided rubber, and the conductive path in the bead portion includes the bead core, the bead filler, and the rubber chaser. You can stay.

According to this configuration, since the rubber cheher generally has conductivity, the conductive path can be configured including the rubber cheher.

The bead portion includes a carcass ply that is folded back from the inside to the outside in the tire width direction so as to sandwich the bead core and the bead filler, and the conductive path in the bead portion includes the bead core, the bead filler, and the rubber chain. and the carcass ply.

According to this configuration, since the carcass ply generally has conductivity, the conductive path can be configured including the carcass ply.

An overlapping amount of the coating material of the dual-side rubber of the sidewall portion may be 1.0 mm or more.

With this configuration, it is possible to secure a sufficient amount of conductivity in the conductive path of the sidewall portion.

In a second aspect of the present invention, a dual-side rubber is prepared in which a core material that is a ribbon-shaped non-conductive rubber is partially covered with a coating material that is a film-shaped conductive rubber, and adjacent in the tire meridian cross section. A method for manufacturing a pneumatic tire, comprising: forming a sidewall portion by spirally winding the dual-side rubber so that the coating material of the dual-side rubber overlaps, wherein the dual-side rubber of the sidewall portion is At least a part of the shoulder portion is partially covered by a coating material whose core material is a ribbon-like non-conductive rubber and whose core material is a film-like conductive rubber. In the shoulder portion, the dual cap rubber is spirally wound so that the covering material of the dual cap rubber adjacent in the tire meridian cross section overlaps and the The covering member of the dual cap rubber of the shoulder portion is partially exposed on the outer surface of the shoulder portion, and the covering member of the dual side rubber of the sidewall portion is in contact with the covering member of the dual side rubber. A method for manufacturing a pneumatic tire is provided, wherein the conductive path includes the dual cap rubber, and each of the coatings of the overlapping dual cap rubber is partially exposed on the outer surface of the shoulder portion. .

According to this method, as described above, a conductive path from the bead portion to the shoulder portion can be secured even when the ribbon construction method is used.

According to the present invention, in the pneumatic tire and its manufacturing method, dual ribbon rubber is adopted for the sidewall portion, so that the conductivity from the rim (bead portion) to the ground surface (shoulder portion) when the ribbon construction method is used route can be secured.

1 is a schematic meridian half-sectional view of a pneumatic tire according to an embodiment of the present invention; FIG. FIG. 4 is a schematic side view showing a wound state of strip rubber on the sidewall portion; FIG. 3 is a schematic cross-sectional view of the strip rubber taken along line III-III in FIG. 2; FIG. 4 is a schematic cross-sectional view showing a wound state of the dual-side rubber; FIG. 2 is an enlarged view of the shoulder portion of FIG. 1; FIG. 2 is an enlarged view of a shoulder portion of a modification of the pneumatic tire of FIG. 1;

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic meridional half-sectional view of a pneumatic tire AT manufactured by a manufacturing method according to the present embodiment. For clarity of illustration, hatching indicating a cross section is omitted. A pneumatic tire AT is provided with a carcass ply 2, a belt layer 3, and a reinforcing layer 4 from an inner liner 1 located on the inner diameter side in the tire radial direction toward the tire outer diameter side. Both ends of the carcass ply 2 extend to the bead core 5 and are folded back from the inside to the outside of the tire so as to sandwich the bead core 5 and the bead filler 6 .

The pneumatic tire AT has, on its surface, a tread portion 7 serving as a tread portion, shoulder portions 8 adjacent to the tread portion 7 and arranged on both outer sides in the tire width direction TW, sidewall portions 9 adjacent to the shoulder portions 8, and a bead portion 10 adjacent to the sidewall portion 9 . A rubber chaser 11 is arranged on the bead portion 10 adjacent to the sidewall portion 9 on the outer side of the carcass ply 2 in the tire width direction TW.

In the tread portion 7 and the shoulder portion 8, the belt layer 3 includes a first belt portion 3a arranged inside in the tire radial direction TR and a second belt portion 3b arranged outside. The first belt portion 3a extends to the shoulder portion 8 in the tire width direction TW. The reinforcing layer 4 is formed by arranging fiber cords of a resin material (for example, nylon 66) in a plurality of rows at predetermined intervals and covering them with a rubber material. The reinforcing layer 4 is spirally wound so as to cover the belt layer 3 . In addition, a plurality of tread grooves 7a are formed on the outer surface of the tread portion 7. As shown in FIG.

The sidewall portion 9 is formed by spirally winding a dual-side rubber 12 having a predetermined shape and material, which will be described later, from the side surface of the shoulder portion 8 to the rubber chain 11 of the bead portion 10 .

The pneumatic tire AT configured as described above is obtained by vulcanizing and molding the green tire GT formed by the ribbon construction method. That is, the green tire GT indicates a raw tire before vulcanization molding, and the pneumatic tire AT indicates a tire as a product after vulcanization molding. Here, since the tread portion 7 and the bead portion 10 are formed by a known construction method (ribbon construction method, etc.), description thereof will be omitted. Hereinafter, the steps of forming the sidewall portion 9 and the shoulder portion 8 will be described in detail.

FIG. 2 is a schematic side view showing the wound state of the dual side rubber 12 of the sidewall portion 9. As shown in FIG. The winding device 15 includes a rotationally driven drum 16 , an extruder 17 that supplies the dual-side rubber 12 to the drum 16 , and a pressing roller 19 that presses the dual-side rubber 12 against the drum 16 .

FIG. 3 is a cross-sectional view of the dual-side rubber 12 taken along line III-III in FIG. The dual-side rubber 12 is composed of a core material 12a, which is a non-conductive ribbon rubber, and a coating material 12b, which is a conductive rubber film, and extends like a ribbon. Here, the term “conductivity” refers to a material property with a volume resistivity of less than 1.0×10 ⁸ (Ω·cm), and the term “non-conductivity” refers to a material property with a volume resistivity of less than 1.0×10 ⁹ (Ω·cm). ) refers to the above material properties.

The cross section of the core member 12a of this embodiment is a flat isosceles triangle shape with a thickness T smaller than the length L of the bottom surface portion 12d. For example, the thickness T of the cross-sectional shape of the dual side rubber 12 of this embodiment is about 2 mm, and the width W is about 30 mm. Here, the width of the dual-side rubber 12 means the width W of the sticking surface to the drum 16 at the time of winding.

In this embodiment, the covering range of the core material 12a with the covering material 12b is a range including the entire bottom surface portion 12d of the core material 12a and two corner portions 12c that are continuous with the bottom surface portion 12d.

FIG. 4 is a schematic cross-sectional view showing the wound state of the dual-side rubber 12. As shown in FIG. In FIG. 4, for the sake of explanation, each dual-side rubber 12 is shown in a state in which the isosceles triangular shape is maintained, that is, in a state before winding. Actually, the dual side rubber 12 is in a deformed state as shown in FIG. 1 by being wound.

When the dual-side rubbers 12 are wound, the coating materials 12b of the adjacent dual-side rubbers 12 come into contact with each other. In FIG. 4 , reference symbol S denotes a portion where the covering members 12b are in contact with each other. That is, the contact portion S represents the overlapping portion between the conductive coating materials 12b of the dual-side rubber 12. As shown in FIG. Preferably, from the viewpoint of conductivity, the size of the contact portion S (overlapping amount of the covering material 12b) is 1.0 mm or more. Thereby, a sufficient amount of conductivity can be secured in the conductive path of the sidewall portion 9 .

Referring again to FIG. 2, the drum 16 is generally columnar and is rotationally driven so that the speed at which the dual-side rubber 12 is adhered to the surface is, for example, 40 to 100 (m/rpm).

The extruder 17 is configured to extrude the heated dual-sided rubber 12 through a die 18 . Here, the heating temperature is set to 120° C. or less so that the dual-side rubber 12 is vulcanized and its physical properties are not changed. The extrusion port of the mouthpiece 18 is formed in an isosceles triangle shape in accordance with the cross-sectional shape of the dual-side rubber 12 (the isosceles triangle shape shown in FIG. 3). However, the cross-sectional shape of the dual side rubber 12 is not limited to an isosceles triangle or other triangular shapes. Alternatively, for example, the cross-sectional shape of the dual-side rubber 12 may be trapezoidal or semicylindrical (substantially semicircular).

The pressing roller 19 is rotatably attached to the tip portion of a rod 21 that protrudes from the cylinder 20 so as to extend and contract. Therefore, the pressure roller 19 contacts and separates from the drum 16 or the green tire GT to wind and press the dual-side rubber 12 at the same time.

The winding device 15 itself is reciprocally movable relative to the drum 16 along its axis of rotation. Thereby, the dual-side rubber 12 can be helically wound around the drum 16 . In this embodiment, the moving speed of the winding device 15 is set so that the feeding pitch of the dual-side rubber 12 wound around the drum 16 is, for example, about 50% of the width W (see FIG. 3).

A method of winding the dual side rubber 12 of the sidewall portion 9 by the winding device 15 having the above configuration is as follows.

First, referring to FIGS. 1 and 2, the dual-side rubber 12 is extruded from the extruder 17 through the mouthpiece 18 while the green tire GT partially formed with the inner liner 1 and the carcass ply 2 is fixed to the drum 16. Push out. When extruded through the mouthpiece 18, the covering material 12b covers the bottom surface 12d and the two corners 12c of the core material 12a as described above (see FIG. 3). At this time, the dual-side rubber 12 is heated in the extruder 17 and softened. However, in this embodiment, since the thickness is about 2 mm, the heating is not necessarily required, and even if the heating is performed, the heat shrinkage after cooling can be suppressed.

Subsequently, the drum 16 is rotated and the pressure roller 19 presses the dual side rubber 12 against the green tire GT. The winding device 15 is moved along the drum 16 at a constant speed. The dual-side rubber 12 is spirally wound around the drum 16 while being overlapped and being sent at a sending pitch (half pitch) that is about half the width dimension in this embodiment. In this embodiment, the sidewall portion 9 is formed by winding the dual-side rubber 12 about five times.

Referring to FIG. 5, in this embodiment, the shoulder portion 8 is also formed by the ribbon construction method. As with the dual side rubber 12 of the sidewall portion 9, the dual cap rubber 13 of the shoulder portion 8 is composed of a core material 13a, which is a non-conductive ribbon rubber, and a coating material 13b, which is a conductive rubber film. extending in the shape of In FIG. 5, the covering members 12b and 13b are shaded for clarity of illustration.

In the shoulder portion 8, the dual cap rubber 13 is spirally wound, and the coating material 13b of the adjacent dual cap rubber 13 overlaps in FIG. 5, which is a tire meridional cross-sectional view. Since the configuration and winding method of the dual cap rubber 13 of the shoulder portion 8 are substantially the same as those of the sidewall portion 9, detailed description thereof will be omitted. This configuration makes the shoulder portion 8 conductive.

The conductive covering material 12b of the dual side rubber 12 of the sidewall portion 9 and the conductive covering material 13b of the dual cap rubber 13 of the shoulder portion 8 are in contact with each other. The conductive covering material 13b of the dual cap rubber 13 of the shoulder portion 8 is partially exposed on the outer surface of the shoulder portion 8. As shown in FIG. With this configuration, a conductive path from the sidewall portion 9 to the ground plane via the shoulder portion 8 can be secured.

In the bead portion 10, the bead core 5, the bead filler 6, the carcass ply 2, and the rubber chaser 11 are electrically conductive. They therefore constitute a conductive path in the bead portion 10 .

The pneumatic tire AT shown in FIG. 1 is completed by vulcanizing the green tire GT formed as described above, for example, at 160° C. for about 30 minutes. In the pneumatic tire AT, a conductive path is formed from the bead portion 10 contacting the rim (not shown) through the sidewall portion 9 to the shoulder portion 8 contacting the ground surface (not shown). That is, the conductive path from the bead portion 10 to the shoulder portion 8 in this embodiment is composed of the bead core 5, the bead filler 6, the carcass ply 2, the rubber chaser 11, the dual side rubber 12, and the dual cap rubber 13 in this order. ing.

According to this embodiment, a conductive path from the bead portion 10 to the shoulder portion 8 via the sidewall portion 9 can be secured even when the ribbon construction method is used. That is, a conductive path can be secured from the rim (not shown) in contact with the bead portion 10 to the ground plane (not shown) in contact with the shoulder portion 8 . In particular, in the sidewall portion 9, the covering material 12b of the dual side rubber 12 overlaps. Therefore, since the conductive members are continuous, a conductive path can be secured.

Further, when the dual-side rubber 12 is spirally wound, the covering material 12b covering the bottom surface portion 12d and the covering material 12b covering the corner portion 12c of the adjacent dual-side rubbers 12 come into contact with each other, thereby ensuring a conductive path. can.

Moreover, since the bead filler 6 has conductivity, a conductive path can be configured including the bead filler 6 .

Moreover, since the rubber cheher 11 has conductivity, a conductive path including the rubber cheher 11 can be formed.

Further, since the carcass ply 2 has conductivity, a conductive path can be configured including the carcass ply 2 .

Further, in this embodiment, the dual cap rubber 13 imparts electrical conductivity to the shoulder portion 8 . In particular, since the covering material of the dual cap rubber is exposed on the outer surface of the shoulder portion 8, a conductive path to the ground plane can be secured. Also, since the covering material 13b of the dual cap rubber 13 of the shoulder portion 8 and the covering material 12b of the dual side rubber 12 of the sidewall portion 9 are in contact with each other, a conductive path from the sidewall portion 9 to the shoulder portion 8 is ensured. can.

Referring to FIG. 6, as a modified example of pneumatic tire AT of the present embodiment, shoulder portion 8 does not have to be formed by the ribbon construction method. Specifically, the tread portion 7 and the shoulder portion 8 may be made of an integral plate-like rubber. At this time, the outer surface of the shoulder portion 8 is provided with a rubber paste portion 8a coated with conductive rubber paste. The covering material 12b of the dual side rubber 12 of the sidewall portion 9 is in contact with the rubber glue portion 8a. In FIG. 6, the covering material 12b and the rubber glue portion 8a are hatched for clarity of illustration. However, in reality, the rubber glue portion 8a is a portion thinly applied to the outer surface of the shoulder portion 8, and may differ in size from the illustration.

According to this modification, the shoulder portion 8a can be made conductive by the rubber glue portion 8a. Further, since the rubber glue portion 8a of the shoulder portion 8 and the covering material 12b of the dual side rubber 12 of the sidewall portion 9 are in contact with each other, a conductive path from the sidewall portion 9 to the shoulder portion 8 can be secured.

In the above-described embodiment and modified examples, the bead core 5, the bead filler 6, the carcass ply 2, the rubber chaser 11, the dual side rubber 12, and the dual cap rubber 13 or the rubber glue portion 8a are exemplified as the conductive path. is not limited to this. For example, the bead filler 6, the carcass ply 2, or the rubber chaser 11 is not essential as a conductive path and may be omitted according to the configuration of the pneumatic tire AT.

In the above-described embodiment and modified example, the covering material 12b of the dual-side rubber 12 covers the corners 12c and the bottom part 12d of the core material 12a. It can be in any form as long as it constitutes a conductive path.

AT... Pneumatic tire GT... Green tire 1... Inner liner 2... Carcass ply 3... Belt layer 3a... First belt part 3b... Second belt part 4... Reinforcement layer 5... Bead core 6... Bead filler 7... Tread part 8... Shoulder part 8a... Rubber glue part 9... Side wall part 10... Bead part 11... Rubber chafer 12... Dual side rubber 12a... Core material 12b... Coating material 12c... Corner part 12d... Bottom part 13... Dual cap rubber 13a... Core material DESCRIPTION OF SYMBOLS 13b... Coating material 15... Winding device 16... Drum 17... Extruder 18... Base 19... Compression roller 20... Cylinder 21... Rod

Claims (7)

a tread portion;
shoulder portions adjacent to the tread portion and arranged on both outer sides in the tire width direction;
a sidewall portion adjacent to the shoulder portion and formed of dual-sided rubber in which a core material of ribbon-shaped non-conductive rubber is partially covered with a coating material of film-shaped conductive rubber;
a bead portion disposed adjacent to the sidewall portion;
A conductive path is provided in which a conductive member is continuously formed from the bead portion to the shoulder portion,
In the sidewall portion, the dual-side rubber is spirally wound, and the covering material of the dual-side rubber adjacent in the tire meridional cross section overlaps to form the conductive path ,
At least part of the shoulder portion is formed of a dual-cap rubber in which a ribbon-shaped non-conductive rubber core material is partially covered with a film-shaped conductive rubber covering material,
In the shoulder portion, the dual cap rubber is spirally wound, and the covering material of the dual cap rubber adjacent in the tire meridian cross section overlaps and is partially exposed on the outer surface of the shoulder portion,
the covering material of the dual cap rubber on the shoulder portion and the covering material of the dual side rubber on the sidewall portion are in contact with each other;
The conductive path in the shoulder portion includes the dual cap rubber,
A pneumatic tire , wherein each of the overlapping dual cap rubber coatings is partially exposed on the outer surface of the shoulder portion. 2. The pneumatic tire according to claim 1, wherein the covering material covers at least a bottom surface portion of the core material, which is a surface on the sticking surface side, and two corner portions that are continuous with the bottom surface portion. the bead portion comprises a conductive bead core and a conductive bead filler adjacent to the bead core;
The pneumatic tire according to claim 1 or 2, wherein the conductive path in the bead portion and the sidewall portion includes at least the bead core, the bead filler, and the dual side rubber. The bead portion includes a conductive rubber chafer interposed between the bead filler and the dual-side rubber,
4. The pneumatic tire according to claim 3, wherein said conductive path in said bead portion includes said bead core, said bead filler, and said rubber chaser. The bead portion includes a carcass ply folded back from the inside to the outside in the tire width direction so as to sandwich the bead core and the bead filler,
The pneumatic tire according to claim 4, wherein the conductive path in the bead portion includes the bead core, the bead filler, the rubber chaser, and the carcass ply. The pneumatic tire according to any one of claims 1 to 5 , wherein an overlapping amount of the covering material of the dual side rubber of the sidewall portion is 1.0 mm or more. preparing a dual-side rubber in which a core material that is a ribbon-shaped non-conductive rubber is partially covered with a coating material that is a film-shaped conductive rubber,
A method for manufacturing a pneumatic tire, comprising: forming a sidewall portion by spirally winding the dual-side rubber so that the coating materials of the dual-side rubbers adjacent to each other in a tire meridian cross section overlap,
The dual-side rubber of the sidewall portion forms part of a conductive path from the bead portion to the shoulder portion ,
At least part of the shoulder portion is formed of a dual-cap rubber in which a ribbon-shaped non-conductive rubber core material is partially covered with a film-shaped conductive rubber covering material,
In the shoulder portion, the dual cap rubber is spirally wound, and the covering material of the dual cap rubber adjacent in the tire meridian cross section overlaps and is partially exposed on the outer surface of the shoulder portion,
the covering material of the dual cap rubber on the shoulder portion and the covering material of the dual side rubber on the sidewall portion are in contact with each other;
The conductive path in the shoulder portion includes the dual cap rubber,
A method for manufacturing a pneumatic tire , wherein each of the covering materials of the overlapping dual cap rubber is partially exposed on the outer surface of the shoulder portion.

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