JP4070504B2 - Manufacturing method of tire tread and tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a tread for a tire that can sufficiently discharge static electricity generated in a vehicle to a road surface while reducing rolling resistance of the tire.
[0002]
[Prior art]
In order to reduce the rolling resistance of tires, there is a tendency to actively replace most of the carbon black compounded in large amounts in tread rubber with silica having low hysteresis loss characteristics. The tread rubber thus produced has a high electrical resistance value, and as a result, there is a problem that static electricity generated in the vehicle is difficult to be discharged to the road surface via the tire.
[0003]
Therefore, for the purpose of ensuring the discharge property of the tread rubber, it constitutes at least a part of the conductive path from the belt to the tread surface disposed in the intermediate portion in the width direction of the tread rubber and the low conductivity tread rubber. Tires having a tread composed of a conductive band have been proposed, and various methods for producing such tire treads have been proposed. In forming a conductive band in these proposals, There is a method of winding a highly conductive unvulcanized rubber ribbon on the outer periphery of a tire material to be rotationally displaced. For example, the one disclosed in JP-A-2002-96402 is known.
[0004]
In addition to this, in order to form a conductive band, a method in which a low conductive tread rubber and a high conductive tread rubber to be a conductive band are integrally formed by a multi-layer extruder, or a low conductive tread rubber is provided. A method of forming a conductive band by pouring a highly conductive rubber cement into the gap is also proposed, but the method of forming a conductive band with the above-described highly conductive unvulcanized rubber ribbon has the following points with respect to these other methods. Is excellent. That is, the former method using a multi-layer extruder is advantageous in that a special design of the extrusion head, a change in the internal shape of the extrusion head, and the like are unnecessary, and the latter method in which a highly conductive rubber cement is poured. The method is advantageous in that the risk of breaking the tread and the like can be sufficiently removed, and a conductive band having a desired shape and size can be easily and quickly formed at a required position.
[0005]
However, problems to be solved regarding the method of forming a conductive band by winding a highly conductive ribbon include the following points. In other words, when winding a highly conductive ribbon, if the ribbon width extends over the entire thickness of the tread, the number of ribbon windings can be reduced, so high productivity can be obtained, but tires of various sizes can be obtained. In the production system, it is necessary to prepare various types of ribbons with various widths corresponding to the cross-sectional shapes of treads that differ depending on the size. On the other hand, if the width of the ribbon is reduced in order to solve such a problem, an attempt is made to form a conductive band connecting the ribbons over the thickness of the tread. Then, in order to obtain a conductive band with the same height as the thickness of the tread, it is necessary to wind and laminate a large number of ribbons, which reduces production efficiency. There is a problem in that.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such a problem, and is a low-conductivity tread rubber and at least a part of a conductive path from a belt to a tread tread disposed in an intermediate portion in the width direction of the tread rubber. When forming the conductive band of the tread consisting of the conductive band that comprises the high-conductivity unvulcanized rubber ribbon, it is possible to compress the intermediate inventory of the ribbon and to make a flexible production system. An object of the present invention is to provide a method for manufacturing a tread for a tire that can increase productivity in winding a vulcanized rubber ribbon.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has been made, and the gist configuration and operation thereof will be described below.
[0008]
The method for manufacturing a tire tread according to claim 1 comprises a tread rubber made of a low-conductivity rubber, and at least a part of a conductive path from a belt to a tread surface disposed in an intermediate portion in the width direction of the tread rubber. A tread for a tire formed by wrapping a highly conductive unvulcanized rubber ribbon around the outer periphery of a tire material to be rotationally displaced, the tire tread having at least one tread layer composed of a conductive band In the manufacturing method of
The highly conductive unvulcanized rubber having a side surface inclined with respect to the equator plane of the tire material and having a width narrower than the width of the inclined side surface after the unvulcanized tread rubber to be a part of the tread rubber is wound and arranged. A rubber ribbon is wound around the entire length of the ribbon so that at least a part of the ribbon in the width direction contacts the inclined side surface to form the tread layer.
[0009]
According to the method for manufacturing a tread for a tire according to the present invention, since the width of the highly conductive unvulcanized rubber ribbon is narrower than the width of the inclined side surface, if only one type of rubber ribbon is prepared, the ribbon Can be used to form conductive bands of tread layers of different thicknesses, enabling compression of intermediate inventory of ribbons and flexible production regimes.
[0010]
Further, in this tire tread manufacturing method, an unvulcanized tread rubber having an inclined side surface is wound and disposed, and then the ribbon is wound so that at least a part in the width direction contacts the inclined side surface over the entire length. Even if this ribbon is made narrow, it is possible to improve the positional accuracy of the conductive band by winding the ribbon with the inclined side surface of the unvulcanized tread rubber as the support surface without relying on the lamination of the ribbons. In addition, a conductive band conducting from the inner peripheral layer of the tread to the tread surface can be formed with a small number of ribbon layers, and productivity at the time of winding the ribbon can be improved. For example, when the conductive band is viewed in the meridian section of the tire, if the conductive band is formed by separating the ribbons from each other without making contact with each other, the number of ribbon windings can be reduced. Thus, a conductive band cannot be formed, and the inclined side surface is essential. Even in this case, since the ribbon is continuous over the entire length, conduction from the inner peripheral layer of the tread to the tread surface is ensured.
[0011]
In the tread formed by this method, the conductive band is disposed in the middle portion in the width direction of the tread rubber. However, when the conductive band is in the width direction side portion of the tread rubber, a conductive layer is formed. Since the appearance of the material is significantly different from that of low-conductivity tread rubber, the conductive layer is exposed in the product tire and the appearance of the tire is impaired, and there is a concern about peeling of the conductive layer. A tread arranged in the middle part of the direction is advantageous.
[0012]
A tire tread manufacturing method according to a second aspect is the method according to the first aspect, wherein the tread layer is formed using the outermost layer of the tire material as another tread layer.
[0013]
According to this tire tread manufacturing method, even in a tread composed of a plurality of tread layers such as a tread having a cap-base structure, the tread layer is claimed on the outermost layer of the tire material as another tread layer. Since it can be formed by the method described in Item 1, in addition to the effect of the method for manufacturing a tire tread described in Item 1, it is possible to manufacture a tread having a plurality of tread layers, and the inside of the tread. An electrical conduction path from the circumferential surface to the tread surface can be formed.
[0014]
The method for producing a tire tread according to claim 3 is the method according to any one of claims 1 to 2, wherein the unvulcanized tread rubber is used as a low-conductivity non-conductive material on the circumference of the rotating tire material. It is formed by winding a vulcanized rubber ribbon.
[0015]
According to this tire tread manufacturing method, one type of low-conductivity unvulcanized rubber ribbon can be used to form unvulcanized tread rubber having various cross-sectional shapes, and the tread rubber shape, dimensions, etc. The degree of design freedom can be increased.
[0016]
The tire according to claim 4 is a tire including a tread formed by the manufacturing method according to any one of claims 1 to 3,
In any tire rotation position, the conductive band of the tread that is in contact with the road surface is an arbitrary straight line extending in parallel to the tire rotation axis between the bottom of the tread groove and the tread surface in the tire meridian cross section. It has a portion that intersects.
[0017]
According to this tire, in addition to the above-described action, the conductive band of the tread that is in contact with the road surface is at least between the bottom of the tread groove and the tread surface in the tire meridian cross section at any tire rotation position. Since it has a portion intersecting with an arbitrary straight line extending in parallel to the tire rotation axis, the tire stops at any rotational position from the initial tread wear to the wear stage where the tread groove disappears. The conductive band can be brought into contact with the road surface, so that the electric charge charged to the vehicle can be released to the road surface not only when the vehicle is traveling but also when the vehicle is stopped, and safety can be ensured.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a side view schematically showing an embodiment of a method according to the present invention. The unvulcanized rubber ribbon 1 has a width of about 1 to 80 mm and a thickness of about 1 to 80 mm, which is extruded by an extruder 2, for example, with a die, a base, etc., regardless of whether it is highly conductive or lowly conductive. It is molded as a long body having a cross-sectional shape of about 0.2 to 7.0 mm. And the unvulcanized rubber ribbon 1 continuously formed in this way is based on the rotational motion of the rotary support 3 and is directly or directly laminated on the outer peripheral surface of the tire material. 4 is indirectly wound via 4 and is stuck and molded there under the pressing action of the sticking roller 5.
[0019]
Here, when the rotating support 3 has an outer peripheral surface shape corresponding to the inner peripheral surface shape of the product tire, and many are high-rigidity cores, a tire molding drum, in particular, it is affixed on the peripheral surface. There is a case where the center portion of the worn carcass band is in a shaping posture in which the central portion of the carcass band is greatly bulged and deformed in the radial direction, a belt tread drum, a retread tire.
[0020]
Further, when the tire material 4 includes an inner liner, a carcass, and a belt that are sequentially laminated on a core or a tire molding drum, or a belt that is adhered and molded on a belt tread drum, And for retreaded tires, there are cases where the base tire itself and a tread undercushion rubber layer adhered to its peripheral surface are provided, and this tread undercushion rubber layer is molded in each of the previous cases. In addition, it may be attached to the outer peripheral side of the belt.
[0021]
When the tread is composed of a plurality of tread layers such as a cap / base structure, any of the above-described tire materials 4 is adjacent to the inner side in the radial direction of the tread layer formed by winding the unvulcanized rubber ribbon 1. An unvulcanized tread layer serving as a tread layer may be provided in the outermost layer. Moreover, the outermost layer of the tire material 4 is made of highly conductive rubber in any case.
[0022]
FIG. 2 is a cross-sectional view in the tread width direction showing a conductive band formation mode according to the present invention, in which 3 is any one of the rotary supports described above, and 4 is any of the tire materials described above. The tire material 4 shown in the figure has an unvulcanized belt cord coating rubber layer 6 made of highly conductive rubber on the outermost layer.
[0023]
The unvulcanized tread 7 here is composed of only one unvulcanized tread layer 7a, and this tread layer 7a is composed of an unvulcanized low-conductivity tread rubber 8. It is assumed that an unvulcanized conductive band 9 extending from the belt cord coating rubber layer 6 on the inner peripheral side of the tread layer 7a to the outer peripheral surface S1 of the tread layer 7a is provided in an intermediate portion in the width direction, in the drawing, at a substantially central portion.
[0024]
In order to realize such a structure, a part 8a of the unvulcanized tread rubber 8 having an inclined side surface S2 inclined by a predetermined angle θ with respect to the equatorial plane E is wound around the circumferential surface of the tire material 4 and disposed. Then, a highly conductive unvulcanized rubber ribbon 10 having a volume resistivity at 25 ° C. of preferably 10 ⁶ Ω · cm or less, which is extruded as shown in FIG. The conductive band 9 is formed by pasting the start end and then winding the tire material 4 and consequently the rotating support 3 under the rotational displacement of the rotating support 3 along the inclined side surface S2. Thereafter, the remaining portion 8b of the unvulcanized tread rubber 8 is wound and arranged to complete the formation of the unvulcanized tread 7.
[0025]
Here, since the width W2 of the highly conductive unvulcanized rubber ribbon 10 is narrower than the width W1 of the inclined side surface S2, the thickness of the tread layer 7a and the inclined side surface S2 of the tread rubber part 8a are independent of the width of the ribbon 10. Therefore, the degree of freedom of design with respect to the shape, dimensions, etc. of the tread rubber can be increased, and at least a part of the ribbon 10 in the ribbon width direction contacts the inclined side surface S2 over the entire length thereof. Thus, the ribbon 10 can be stably positioned over its entire length.
[0026]
In addition, in the formation of both the part 8a and the remaining part 8b of the unvulcanized tread rubber 8 which is molded by being wound and arranged as described above, the low-conductivity unvulcanized material on the tire material 4 is formed. A rubber ribbon, for example, a rubber ribbon having a rectangular cross-sectional shape with a width of about 5 to 30 mm and a thickness of about 0.2 to 7.0 mm can be wound, and the cross section of a part 8a or the remaining part 8b of the tread rubber 8 It can also be formed of an integrally extruded molded body of low-conductivity unvulcanized rubber having a high degree of design freedom with respect to the shape, dimensions, etc. of the tread rubber according to the former, and according to the latter, molding Work efficiency can be increased.
[0027]
FIG. 3 is a cross-sectional view in the width direction of a tread showing another embodiment. In this embodiment, when the tread 13 composed of two tread layers of the cap base structure is formed, the base portion is not yet formed. A vulcanized base tread layer 7b is formed on a tire material 4 having an unvulcanized belt cord coating rubber layer 6 made of a highly conductive rubber as an outermost layer, and then an unvulcanized cap tread that becomes a cap portion. The layer 7c is formed on the tire material 16 having the base tread layer 7b as the outermost layer.
[0028]
In forming the base tread layer 7b, according to the above description, the unvulcanized tread rubber 11 having the inclined side surface S4 inclined by the predetermined angle θ1 with respect to the equator plane E is formed on the circumferential surface of the tire material 4. After winding and arranging the portion 11a, the highly conductive unvulcanized rubber ribbon 10 is affixed to the peripheral surface of the tire material 4 with the start end and then wound along the inclined side surface S4 under the rotational displacement of the tire material 4. Then, the unvulcanized conductive band 12 is formed, and then the remaining portion 11b of the unvulcanized tread rubber 11 is wound and arranged.
[0029]
Similarly, when the capto red layer 7c is formed, an unvulcanized surface having an inclined side surface S5 inclined by a predetermined angle θ2 with respect to the equator plane E is formed on the peripheral surface of the base tread layer 7b forming the outermost layer of the tire material 16. After the part 14a of the tread rubber 14 is wound and arranged, the highly conductive unvulcanized rubber ribbon 10 is affixed to the conductive band 12 of the base tread layer 7b, and this is subjected to the rotational displacement of the tire material 4. The unvulcanized conductive band 15 is formed by winding along the inclined side surface S4, and then the remaining portion 14b of the unvulcanized tread rubber 14 is wound and disposed. In this way, it is possible to form the conductive band 12 and the conductive band 15 which constitute a part of the conductive path extending from the belt to the outer peripheral surface S3 of the tread and are electrically connected to each other.
[0030]
Also in this embodiment, the part 11a and the remaining part 11b of the tread rubber 11 and the part 14a of the tread rubber 14 are all formed by winding a low-conductivity unvulcanized rubber ribbon on the tire material. In addition to the above, it can be formed by an integrally extruded body as described above, and the effects in each case are also as described above.
[0031]
In FIG. 3, the conductive band 15 of the cap tread layer 7c is inclined in the opposite direction with respect to the equatorial plane E with respect to the conductive band 12 of the base tread layer 7b. 4 may be inclined in the same direction with respect to the equatorial plane E, and the tread 13 shown in FIG. 3 is composed of two tread layers 7b and 7c. The number of tread layers constituting the tread may be more than two. In this case, the formation of each tread layer can be performed as described above.
[0032]
Further, in forming the conductive bands 12 and 15 shown in FIG. 3, a part of the ribbons 10 appearing in the tire meridian cross section is shown in FIG. In this case, since the ribbon 10 is continuous over the entire length, the ribbon 10 is secured after satisfying the requirement of forming a part of the conduction path from the belt to the tread outer peripheral surface. Can be shortened and can contribute to the improvement of productivity. However, with respect to the ribbon 10 located radially outside the straight line L1 parallel to the axis of the tire material 4 at the height position of the unvulcanized tread corresponding to the bottom of the tread groove formed by vulcanization molding, It is important to arrange the ribbons 10 so as to be in contact with each other even in the cross section of the tire meridian. In the arrangement of the ribbon 10 as shown in FIG. 5, since the ribbons 10 cannot be stacked in the radial direction while being stacked on each other, an unvulcanized tread that is arranged prior to winding of the ribbon 10 is used. It is essential that the rubber portions 11a and 14a have inclined side surfaces S4 and S5.
[0033]
FIG. 6 is a tire meridian cross section showing a part of a tread 23 of a tire 20 made by vulcanizing an unvulcanized tire having conductive bands 12 and 15 formed by winding a ribbon 10 in accordance with what is shown in FIG. FIG. The tread 23 of the tire 20 includes a base tread 21, a cap tread 22, and a conductive band 26 formed by vulcanizing the unvulcanized conductive bands 12 and 15, and includes a tread groove 24 extending in the circumferential direction. The conductive band 26 formed in accordance with the position shown in FIG. 5 is at least between the bottom 25 of the tread groove 24 and the tread tread surface in the tire meridian section of the tread 23 portion of the tread 23 portion that contacts the road surface at any tire rotation position. D will inevitably have a portion intersecting with an arbitrary straight line L extending in parallel with the tire rotation axis, and this leads to a wear stage where the tread groove 24 disappears from the initial wear of the tread 23. Even if the tire 20 stops at any rotational position, the conductive band 26 can be brought into contact with the road surface, so that the electric charge charged to the vehicle can be released to the road surface not only when the vehicle is running but also when the vehicle is stopped.
[0034]
【The invention's effect】
As is apparent from the above description, according to the present invention, since the width of the highly conductive unvulcanized rubber ribbon is narrower than the width of the inclined side surface, treads having different thicknesses with only one type of rubber ribbon. A conductive band of layers can be formed, which enables compression of the intermediate inventory of the ribbon and flexible production system, and after wrapping and arranging unvulcanized tread rubber with inclined sides, Since the conductive band is formed by winding so that at least a part of the direction contacts the inclined side surface, even if this ribbon is made narrow, the ribbon is unvulcanized tread rubber without relying on the lamination of the ribbons. In addition to increasing the position accuracy of the conductive band by winding the inclined side surface of the belt as a support surface, the conductive band conducting from the inner peripheral layer of the tread to the tread surface is formed with a small number of ribbon layers. It can, it is possible to improve the productivity at the time of winding ribbon.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing an embodiment of a method according to the present invention.
FIG. 2 is a cross-sectional view in the tread width direction showing a mode of forming a conductive layer according to the present invention.
FIG. 3 is a cross-sectional view in the tread width direction showing how a conductive layer is formed on a tread having a cap-base structure.
FIG. 4 is a cross-sectional view in the tread width direction showing another form of forming a conductive layer.
FIG. 5 is a cross-sectional view in the tread width direction showing another form of forming a conductive layer.
FIG. 6 is a cross-sectional view showing a tread of a tire having a conductive layer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Unvulcanized rubber ribbon 2 Extruder 3 Rotating support 4 and 16 Tire material 5 Sticking roller 6 Unvulcanized belt cord coating rubber layer 7 and 13 Unvulcanized tread 7a Unvulcanized tread layer 7b Unvulcanized tread layer 7b Base tread layer 7c Unvulcanized cap tread layer 8, 11, 14 Unvulcanized tread rubber 8a, 11a, 14a Part of unvulcanized tread rubber 8b, 11b, 14b Remaining portion 9 of unvulcanized tread rubber , 12, 15 Conductive band 10 Highly conductive unvulcanized rubber ribbon 20 Tire 21 Base tread 22 Cap tread 23 Tread 24 Tread groove 25 Tread groove bottom 26 Conductive band S1, S3 Tread outer peripheral surface S2, S4, S5 Inclined side face L Tire Straight line parallel to the axis L1 Straight line parallel to the tire material

Claims (4)

It comprises at least one tread layer comprising a tread rubber made of a low conductive rubber and a conductive band that is disposed at an intermediate portion in the width direction of the tread rubber and forms at least a part of a conductive path from the belt to the tread surface. In the manufacturing method of a tire tread, the conductive band of the tire tread is formed by winding a highly conductive unvulcanized rubber ribbon on the outer periphery of a tire material to be rotationally displaced.
The highly conductive unvulcanized rubber having a side surface inclined with respect to the equator plane of the tire material and having a width narrower than the width of the inclined side surface after the unvulcanized tread rubber to be a part of the tread rubber is wound and arranged. A method for manufacturing a tread for a tire, comprising forming a tread layer by winding a rubber ribbon so that at least a part of the ribbon in the width direction is in contact with an inclined side surface over the entire length of the ribbon. The method for manufacturing a tread for a tire according to claim 1, wherein the tread layer is formed by using the outermost layer of the tire material as another tread layer.   The method for producing a tire tread according to any one of claims 1 to 2, wherein the unvulcanized tread rubber is formed by winding a low-conductivity unvulcanized rubber ribbon around a circumference of a tire material. A tire comprising a tread formed by the manufacturing method according to claim 1 ,
In any tire rotation position, the conductive band of the tread that is in contact with the road surface is an arbitrary straight line extending in parallel to the tire rotation axis at least from the bottom of the tread groove to the tread surface in the tire meridian cross section. A tire having a crossing portion.

Images