JP2008213750A - Pneumatic tire and manufacturing method for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a coulisse from being generated on a surface of a different color rubber layer for forming a different color part of a pneumatic tire, and thereby to enhance crack durability of a side wall part. <P>SOLUTION: A white ribbon-like rubber 42G is laminated on an outer surface side of a rolling-up part 20B of a carcass rolled-up to the side wall part 3 of the pneumatic tire to form a laminated part 42, and a white first cover rubber 43 is provided on the outer surface to form the different color rubber layer 41. A second cover rubber 44 comprising a black rubber is arranged on an outer surface of the different color rubber layer 41, a part is ground to expose the different color rubber layer 41, and the different color part 40 comprising a white rubber is formed on the outer surface of the side wall part 3. A rolled-up end 20C of the carcass 20 is arranged on an outer side in a tire radial direction relative to the laminated part 42. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a different color portion of a color different from the surroundings is provided on an outer surface of a sidewall portion, and a method for manufacturing the same, and in particular, a different color rubber layer that forms a different color portion is formed by laminating ribbon-like rubber. In addition, the present invention relates to a pneumatic tire having improved crack durability in a sidewall portion and a method for manufacturing the pneumatic tire.

  A pneumatic tire, for example, a pneumatic radial tire having a radial structure, generally includes a bead core disposed in a pair of bead portions, and a carcass formed of one or more carcass plies extending in a toroidal shape therebetween. The end portion of the carcass is folded up around the bead core from the inside to the outside of the tire and wound up to the sidewall portion toward the outside in the tire radial direction. As such a pneumatic tire, conventionally, the outer surface of the at least one sidewall portion (the outer surface in the tire width direction) is a different color portion made of rubber different in color from the other portions of the tire, for example, white against the surrounding black There are known lines and tire sizes, manufacturer names, characters and symbols such as logos, etc., which have improved appearance (see Patent Document 1).

FIG. 6 is a perspective view schematically showing a part of the outer surface of the sidewall portion in which the different color portion of this conventional pneumatic tire is formed. In the figure, the portion where the letter “I” is formed is enlarged. As shown.
In this pneumatic tire 100, as shown in the drawing, most of the outer surface 101A of the sidewall portion 101 is composed of a black rubber portion 102 having the same color as the other portions of the pneumatic tire 100, and the tire circumferential direction is included therein. Along with (arrow T in the figure), a plurality (one in the figure) of different color parts (here, white rubber part 103) of a color different from the surrounding black are provided, thereby forming characters, symbols, and the like. .

  FIG. 7 is a schematic diagram illustrating a procedure for forming the white rubber portion 103 on the outer surface 101A of the sidewall portion 101 of the pneumatic tire 100, and is a cross-sectional view corresponding to the ZZ arrow in FIG.

  In order to form the white rubber portion 103, first, as shown in FIG. 7A, at the stage of molding a green tire (raw tire) 110, a black ribbon rubber (long length) is formed on the outer surface of the carcass 111 serving as a base. A rubber member) is wound and laminated while forming a tread rubber, a sidewall rubber or the like (not shown), and a white portion is formed at a predetermined position of the sidewall portion 101 (a portion where the white rubber portion 103 is formed). A ribbon-shaped rubber is laminated to form a laminated portion 112 having a predetermined cross-sectional shape. Subsequently, the green tire 110 is molded by attaching a black cover rubber 113 to at least the surface of the laminated portion 112.

  Next, the green tire 110 is accommodated in a mold having a concave portion corresponding to the white rubber portion 103 and vulcanized, and as shown in FIG. 7B, the pneumatic tire 100 ( The portion of the sidewall portion 101) where the white rubber portion 103 is formed protrudes (the protruding portion 114 in the figure) from the other portions. Thereafter, the surface of the protruding portion 114 is ground by buffing or the like to remove the cover rubber 113, and the laminated portion 112 made of white rubber is applied to the surface 101A of the sidewall portion 101 as shown in FIG. 7C. Expose. As a result, a white rubber portion 103 (see FIG. 6) that slightly protrudes from the black rubber portion 102 is formed on the sidewall portion 101.

  However, when the green tire 110 is formed of the ribbon-like rubber in this way, irregularities are formed on the surface due to steps or the like of the outer surface of the laminated ribbon-like rubber, and as a result, the pneumatic tire 100 after vulcanization molding is formed. Small wrinkles may occur on the surface of the surface. In particular, the white rubber forming the laminated portion 112 has lower fluidity (rubber flowability) at the time of vulcanization molding than other black rubbers, so that the unevenness of the surface is difficult to be buried at the time of vulcanization molding. There is a tendency that Chris is more likely to occur. In addition, since white rubber has low crack resistance (crack) progress after vulcanization molding, the Chris generated on the surface tends to be the core of the crack. As a result, in this pneumatic tire 100, cracks may develop from the surface of the laminated portion 112, and the crack durability of the sidewall portion 101 may be reduced.

  In the pneumatic tire 100, the winding end wound up to the sidewall portion 101 of the carcass 111 may be disposed in the laminated portion 112. In such a case, the unevenness on the surface of the laminated portion 112 is further increased due to the level difference across the winding end of the carcass 111, so that it becomes easier to produce Chris around the vicinity, and the degree of deterioration becomes worse. The risk of a decrease in crack durability is also increased.

JP 2005-212197 A

  The present invention has been made in view of the above-described conventional problems, and the object thereof is a pneumatic structure in which ribbon-shaped rubber is laminated on the outer surface of the sidewall portion to form a different color portion having a different color from other portions. In a tire, it is suppressing the generation | occurrence | production of Chris on the surface of the different color rubber layer which forms the different color part, and improving the crack durability of a side wall part.

The invention of claim 1 includes a carcass extending between a pair of bead cores, folded around the bead core from the inside to the outside of the tire, and wound up to the side wall in the tire radial direction. A pneumatic tire provided with a different color part different in color from other parts on the outer surface of the carcass, formed by laminating ribbon-like rubber of the same color as the different color part, and the rolled-up carcass of the sidewall part The laminated portion disposed on the outer surface side, and a first cover rubber having the same color as the different colored portion provided on the outer surface of the laminated portion, the different colored rubber layer forming the different colored portion, and the different colored rubber layer A second cover rubber having the same color as that of the other portion covering the outer surface other than the different color portion, and the winding end of the carcass is disposed on the outer side in the tire radial direction of the laminated portion. And features.
According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the ribbon-like rubber of the laminated portion is laminated along the wound carcass and viewed in a cross section in the tire width direction. It is characterized by being laminated at an angle of 10 to 40 ° with respect to the carcass at the position.
A third aspect of the present invention is the pneumatic tire according to the first or second aspect, wherein the thickness of the first cover rubber is 0.4 to 1.2 mm.
According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the ratio of the thickness of the thickest portion to the thickness of the thinnest portion of the second cover rubber is 1. It is in the range of 0 to 1.3.
The invention according to claim 5 includes a carcass extending between a pair of bead cores, folded around the bead core from the inside to the outside of the tire and wound up to the sidewall portion toward the outside in the tire radial direction, A method of manufacturing a pneumatic tire in which a different color portion different in color from other portions is provided on an outer surface of the tire, wherein a ribbon-like rubber having the same color as the different color portion is laminated along a winding portion excluding a winding end of the carcass A step of forming a different color rubber layer for forming the different color portion by adhering a first cover rubber having the same color as the different color portion to the surface of the laminated ribbon-like rubber, and the first cover rubber And attaching a second cover rubber having the same color as that of the other portion to cover the surface of the different color rubber layer.
According to a sixth aspect of the present invention, in the method for manufacturing a pneumatic tire according to the fifth aspect, in the laminating step, the ribbon-shaped rubber is wound up at each laminating position as seen in a cross section in the tire width direction. It is characterized by being laminated so as to have an angle of 10 to 40 ° with respect to the carcass.
A seventh aspect of the present invention is the method of manufacturing a pneumatic tire according to the fifth or sixth aspect, wherein the thickness of the first cover rubber is 0.4 to 1.2 mm.

  According to the present invention, in a pneumatic tire in which a ribbon-shaped rubber is laminated on the outer surface of the sidewall portion to form a different color portion having a different color from other portions, the surface of the different color rubber layer that forms the different color portion is formed. The occurrence of Chris can be suppressed, and the crack durability of the sidewall portion can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The pneumatic tire of this embodiment is a different color portion made of rubber having a color different from that of the other portion on the outer surface of at least one sidewall portion, similar to the conventional pneumatic tire 100 shown in FIGS. 6 and 7. Thus, lines, characters, symbols, and the like are formed in other colors such as white and yellow with respect to the surrounding color (here, black). The “other portion” referred to here is a portion other than the different color portion on the outer surface of the sidewall portion, for example, a rubber constituting most of the pneumatic tire excluding the different color rubber layer forming the different color portion ( Main rubber) and the same color rubber.

FIG. 1 is a half cross-sectional view in the tire width direction schematically showing the overall structure of the pneumatic tire of the present embodiment.
As shown in the figure, the pneumatic tire 1 includes a pair of bead portions 2 located on the inner side in the tire radial direction (lower side in the drawing) and the outer side in the tire radial direction (upper side in the drawing) from the bead portion 2. The sidewall portion 3 that extends and the substantially cylindrical tread portion 4 that connects the outer ends in the tire radial direction of the sidewall portions 3 are provided, and a different color portion 40 is provided on the outer surface of the sidewall portion 3 near the center. ing.

  The pneumatic tire 1 includes a canvas chafer 10 for protecting the bead portion 2 provided from the inner end in the tire radial direction of the bead portion 2 to the inner side in the width direction (right side in the drawing), and the bead portion 2. Between the pair of bead cores 11, a pair of bead cores 11 having a substantially rectangular cross section embedded in the vicinity of the inner end in the tire radial direction, a bead filler 12 extending from the outer peripheral surface of the bead core 11 toward the outer side in the tire radial direction. And a tread rubber 13 constituting the outer peripheral surface of the tread portion 4. Further, at least one belt layer (here, two layers) in order from the inner side in the tire radial direction to the outer side (from the lower side to the upper side in the figure) on the outer peripheral side (the tire radial direction outer side) of the carcass 20 of the tread portion 4. 14 and 15 and at least one belt reinforcing layer 16 (here, one layer), which are adjacent to each other in the tire radial direction and overlap each other, between the carcass 20 and the tread rubber 13. It is arranged.

  The carcass 20 is composed of at least one layer (here, two layers) of carcass plies 21 and 22 having a radial structure, for example, in a toroidal shape from the bead core 11 disposed in the bead portion 2 through the sidewall portion 3 and the tread portion 4. At the same time, both end portions are folded up around the bead core 11 from the inner side of the tire to the outer side (from the right side to the left side in the drawing) and wound up to the side wall portion 3 toward the outer side in the tire radial direction. The carcass plies 21 and 22 of the carcass 20 are provided with a plurality of skeleton elements each made of, for example, steel or an organic fiber cord extending in a substantially radial direction (meridian direction), and are overlapped to form the carcass 20. is doing. Further, the carcass 20 is provided along the outer surfaces so as to wrap the bead core 11 and the bead filler 12, and the main body portion 20 </ b> A on the inner side in the tire width direction and the outer winding portion 20 </ b> B are separated on the bead core 11 side. The bead filler 12 is disposed so as to overlap each other from the tip end of the bead filler 12 to the winding end 20C of the winding portion 20B.

  The belt layers 14 and 15 are formed such that the inner belt layer 14 in the tire radial direction is wider than the outer belt layer 15 and the outer end in the tire width direction is separated from the carcass 20 with the belt undercushion rubber 17 interposed therebetween. , Is arranged near the tread end TE. Each of the belt layers 14 and 15 has a plurality of reinforcing elements made of, for example, steel or organic fiber cords arranged in parallel, and they are inclined in opposite directions with respect to the tire equatorial plane CL. And are arranged to intersect.

  The belt reinforcing layer 16 is formed wider than the wide belt layer 14 and is disposed so as to cover the belt layers 14 and 15 from the outer side in the tire radial direction to the vicinity of the shoulder portions (shoulder portions) 5 on both sides of the tread portion 4. ing. The belt reinforcing layer 16 has reinforcing elements arranged in parallel in the tire width direction extending substantially in the tire circumferential direction. For example, one reinforcing element is wound around the outer periphery of the belt layers 14 and 15 in a spiral shape (spiral shape). Formed.

  The tread rubber 13 is a rubber layer that is in contact with the road surface when the tire rolls, and a predetermined tread pattern (not shown) made of various grooves such as a circumferential main groove and a sipe is formed on the outer peripheral surface (tread surface). Has been. The tread rubber 13 is formed by, for example, black ribbon-like rubber being spirally wound around the outer periphery of a lower layer member such as the belt reinforcing layer 16 or the belt undercushion rubber 17 so as to overlap one part or a plurality of layers. Formed.

  Further, in the pneumatic tire 1 of the present embodiment, the outer surface side (outer side in the tire width direction) of the carcass 20 of the sidewall portion 3 is formed by laminating ribbon-like rubber or the like, similarly to the tread rubber 13. That is, on the outer surface side of the sidewall portion 3, the upper side wall rubber 30 connected to the tread portion 4 (tread rubber 13), the lower side wall rubber 31 connected to the bead portion 2 (bead outer surface rubber 2A), and the upper and lower sides An intermediate side wall rubber 32 disposed between the wall rubbers 30 and 31 and provided with a different color portion 40. The upper and lower side wall rubbers 30 and 31 are made of black ribbon rubber and the outer surface of the carcass 20. Is formed by laminating along. On the other hand, the intermediate sidewall rubber 32 is formed in a multilayer structure composed of a ribbon-like rubber laminated in the same color as the different color portion 40 (here, white) and a two-layer cover rubber laminated on the outer surface thereof.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of the intermediate sidewall rubber 32 (region X in FIG. 1).
In addition, a tire formed by laminating a ribbon-like rubber or the like like this pneumatic tire 1 can be identified by seeing the interface of each laminated member, etc., when cut and viewed after vulcanization molding. Can do. In FIG. 2, in particular, the interface of the intermediate sidewall rubber 32 is extracted and schematically shown.

  As shown in the drawing, the intermediate sidewall rubber 32 includes a laminated portion 42 made of white ribbon-like rubber 42G disposed on the inner side in the tire width direction (carcass 20 side), and the outer side in the tire width direction of the laminated portion 42 (left side in the figure). ), And a first cover rubber 43 and a second cover rubber 44 arranged in this order.

  The laminated portion 42 is formed by laminating white ribbon-like rubber 42G, and is formed between the upper and lower sidewall rubbers 30 and 31 (in the drawing) on the outer surface side of the carcass 20 (rolled portion 20B) wound up of the sidewall portion 3. (Only the upper side wall rubber 30 is shown) and constitutes the inner layer portion of the intermediate side wall rubber 32. Moreover, in this embodiment, the lamination | stacking part 42 is arrange | positioned in the tire radial direction inner side (lower side in a figure) rather than the winding end 20C of the winding part 20B. That is, in the carcass 20 of the present embodiment, the winding part 20B is wound up into the upper side wall rubber 30 beyond the interface 42K between the upper side wall rubber 30 and the intermediate side wall rubber 32 (lamination part 42). The rolled-up end 20C is positioned on the outer side in the tire radial direction by a predetermined length with respect to the upper end (interface 42K) of the stacked portion 42. Thereby, the end part side of the winding-up part 20B of the carcass 20 is protruded from the laminated part 42, and the rolled-up end 20C is disposed on the outer side in the tire radial direction of the laminated part 42.

  Further, in the pneumatic tire 1, the ribbon-like rubber 42G of the laminated portion 42 is moved inward in the tire radial direction from the lower end of the upper side wall rubber 30 along the rolled-up portion 20B excluding the rolled-up end 20C of the wound carcass 20. The laminated portion 42 is formed by sequentially overlapping and winding and laminating up to the upper end of the lower sidewall rubber 31 (not shown). In addition, when viewed in the cross section in the tire width direction, the ribbon-shaped rubber 42G has an angle (stacking angle) θ with respect to the carcass 20 (winding portion 20B) at each stacking position (contact position) being a predetermined angle (here, 10 to 40 °). Are stacked so that the angle is within the range.

  The first cover rubber 43 is a relatively thin rubber layer of the same color (in this case, white) as the different color portion 40 provided to overlap the outer surface of the laminated portion 42 (the outer surface in the tire width direction). The different color rubber layer 41 which forms the different color part 40 with the lamination | stacking part 42 is comprised so that the whole outer surface may be covered. The first cover rubber 43 is made of, for example, a sheet-like rubber member formed to have a predetermined thickness. Here, the first cover rubber 43 is laminated beyond the interface with the upper and lower sidewall rubbers 30 and 31 of the laminated portion 42, The intermediate sidewall rubber 32 is disposed over the entire side wall rubber 32 and end portions of the side wall rubbers 30 and 31. In the present embodiment, the thickness of the first cover rubber 43 is formed within a range of 0.4 to 1.2 mm.

  The second cover rubber 44 is a rubber having the same color (here, black) as the portion other than the different-colored portion 40 on the outer surface of the side wall portion 3 provided on the outer surface of the first cover rubber 43. It is a layer and is laminated on the outer surface of the first cover rubber 43 so as to cover the outer surface of the different color rubber layer 41 other than the different color portion 40 and constitutes the outer surface of the intermediate sidewall rubber 32. Similar to the first cover rubber 43, the second cover rubber 44 is also made of a comparatively thin sheet-like rubber member having a predetermined thickness, for example, and covers the entire first cover rubber 43 except for the different color portion 40. The upper and lower sidewall rubbers 30 and 31 are disposed up to the outer surface.

FIG. 3 is an enlarged sectional view schematically showing the vicinity of a part of the cover rubbers 43 and 44 (Y region in FIG. 2).
As shown in the figure, the first cover rubber 43 is gently curved so that the cross-sectional shape thereof is substantially wavy so as to fill the unevenness (unevenness) of the outer surface of the laminated ribbon-like rubber 42G of the laminated portion 42 as shown in the figure. It is formed in a shape that repeats. Further, the inner surface of the second cover rubber 44 in contact with the first cover rubber 43 is formed to have a concave and convex surface having substantially the same cross section according to the outer surface shape, and is in close contact with the outer surface of the first cover rubber 43. ing. On the other hand, the outer surface (the outer surface of the intermediate sidewall rubber 32) is formed in a substantially flat surface with few irregularities. As a result, the thickness of the second cover rubber 44 varies depending on the outer surface state of the first cover rubber 43 and the laminated portion 42, but in the present embodiment, the thickness T of the thinnest portion is changed. thickest part of the ratio of the thickness _{T 1 H} for _{2 (T} 1 / T ₂₎ has become a value in the range of 1.0 to 1.3.

  On the outer surface (see FIG. 2) of the intermediate sidewall rubber 32 described above, a plurality (two in FIG. 2) of different-colored portions 40 protruding (projecting) from the surrounding surface are formed. In each different color portion 40, at least the second cover rubber 44 is removed, and the different color rubber layer 41 (here, the first cover rubber 43) is exposed on the outer surface. 40 is formed. Further, the size, the degree of bulge, or the arrangement position of the different color portion 40 is determined according to the shape and position of the character to be formed, and depending on them, the first cover rubber 43 is removed and the different color The laminated portion 42 of the rubber layer 41 is exposed on the outer surface.

  Next, an apparatus and a manufacturing process for manufacturing the pneumatic tire 1 according to the present embodiment will be described. The pneumatic tire 1 is formed by vulcanization molding after molding a green tire with unvulcanized rubber or the like. To have a predetermined shape.

FIG. 4 is a side view schematically showing a main part of a tire molding apparatus for molding this green tire, and shows a portion where ribbon-like rubber is laminated.
This tire molding device 60 is a green tire in which a part of unvulcanized ribbon-like rubber 50 is laminated and laminated to form a tread rubber 13 having a predetermined cross-sectional shape, sidewall rubbers 30, 31, 32, and the like. As shown in the figure, a support 61 that is rotatable around an axis, an extruder 62 that supplies a ribbon-like rubber 50, and a pair of rollers 63 and 64 disposed therebetween. And a control device (not shown) for controlling the entire device including a microcomputer or the like.

  The support 61 is a rigid core having a cylindrical molding drum or a toroidal outer shape corresponding to the inner shape of the green tire to be molded, and is rotated around an axis by a rotation driving means (not shown). A tire constituent member or ribbon-like rubber 50 is wound around the outer surface. The extrusion machine 62 has a base 62A having an opening of a predetermined shape, and extrudes unvulcanized rubber from the opening to form a ribbon-like rubber 50 having a predetermined cross-sectional shape (here, substantially rectangular), The ink is continuously supplied between the pair of rollers 63 and 64.

  The pair of rollers 63 and 64 are disposed to face the outer surface of the support 61, and one (upper in the figure) roller 63 is formed to have a larger diameter than the other (lower in the figure) roller 64, and is an extruder. While guiding the ribbon-shaped rubber 50 supplied from 62 toward the support 61, the position and angle thereof are adjusted, and the ribbon-shaped rubber 50 is attached to the outer surface of the support 61 with one large-diameter roller 63. wear. The tire molding device 60 spirals the ribbon-like rubber 50 supplied from the extruder 62 by the rollers 63 and 64 on the outer surface of the support 61 that rotates while adjusting the position, angle, overlap amount, and the like. It is wound and laminated to form a predetermined cross-sectional shape.

  When a green tire is molded by the tire molding device 60, first, tire components such as the inner liner, the carcass 20, the bead core 11 (see FIG. 1) are arranged on the outer surface of the support 61, and the end portion of the carcass 20 is attached. A lower layer member serving as a base is formed by being folded around the bead core 11. Subsequently, the ribbon-like rubber 50 is laminated. When the support 61 is a molding drum, the lamination is started after the central portion of the tire constituent member molded into a cylindrical shape is expanded in a toroidal shape. . At the time of lamination, the black ribbon-like rubbers 50 are laminated as described above to form the tread rubber 13, the upper side wall rubber 30, the lower side wall rubber 31 and the like in a predetermined shape, and the black ribbon-like rubber. 50 is changed to a white ribbon-like rubber 50 (42G), which is similarly laminated at a predetermined position (see FIG. 2) between the upper and lower sidewall rubbers 30 and 31 to form a laminated portion 42.

  When the laminated portion 42 is formed, the white ribbon-like rubber 42G is overlapped with each other from the upper side wall rubber 30 side to the lower side wall rubber 31 side along the winding portion 20B excluding the winding end 20C of the carcass 20. Thus, the laminated portion 42 is formed into a predetermined shape by one (one layer) of lamination operations. Further, when viewed in the cross section in the tire width direction, the ribbon-like rubber 42G is laminated so as to have an angle within a range of 10 to 40 ° with respect to the winding portion 20B of the carcass 20 at each lamination position.

  In the tire molding device 60 of the present embodiment, following the formation of the laminated portion 42, the first cover rubber 43 is attached to at least the surface of the laminated portion 42, and then the second cover rubber 44 is attached. The pasting process is executed. In this pasting process, unvulcanized sheet rubber having a predetermined thickness and shape formed by a rubber molding apparatus such as an extrusion molding machine or a calendar apparatus is used as the cover rubbers 43 and 44, and these are sequentially supported. Affixed to the surface of the sidewall portion 3 of the green tire on the body 61. Therefore, in addition to the above, the tire molding device 60 includes a means for supplying the white first cover rubber 43 and the black second cover rubber 44 formed in a sheet shape toward the support body 61; Pasting means for pasting them in place.

FIG. 5 is a perspective view schematically showing a state in which the first cover rubber 43 is attached to the surface of the one sidewall portion 3.
The first cover rubber 43 may be attached by pressing against the sidewall portion 3 using the viscosity of the rubber. Adhesive or the like may be applied to the attachment portion of the sidewall portion 3 or the first cover rubber 43. After application, the side wall 3 may be pressed and pasted.

  In the sticking step, first, as shown in FIG. 5A, from the supply means (not shown) of the white first cover rubber 43 (sheet rubber) with the support 61 (green tire 55) stopped. Then, the first cover rubber 43 is supplied to the surface of the sidewall portion 3 (arrow K in the figure). Next, when the tip of the first cover rubber 43 reaches a predetermined position of the sidewall portion 3 and, for example, a sensor (not shown) detects this, the tip of the first cover rubber 43 is pressed against the pressing member ( (Not shown) and pressed from the outside in the tire width direction and crimped to a predetermined position of the sidewall portion 3. Subsequently, the pressing member is separated from the first cover rubber 43, and a cylindrical roller 65 that is rotatable at substantially the same position is pressed. At this time, the roller 65 is pressed so that the axial direction of the roller 65 is substantially parallel to the outer surface of the sidewall portion 3 and substantially orthogonal to the rotation direction of the green tire 55 at the pressing position.

  Next, as shown in FIG. 5B, the support 61 is rotated in the same direction (arrow F in the figure) in synchronization with the supply speed of the first cover rubber 43, and the first cover rubber 43 is moved to the sidewall portion 3. Paste along the circumferential direction. At that time, the first cover rubber 43 is pressed by the roller 65 to release air between the lower layer members such as the laminated portion 42, and the first cover rubber 43 is adjusted to the unevenness of the surface of the laminated ribbon rubber. The rubber 43 is pressed while being deformed, and the first cover rubber 43 is pasted while being deformed so as to have a substantially annular shape corresponding to the shape of the sidewall portion 3.

  In this state, the supply of the first cover rubber 43 and the rotation of the support body 61 are continued. As shown in FIG. 5C, the green tire 55 goes around and the tip of the first cover rubber 43 reaches the sticking start position. For example, when a sensor (not shown) detects this, the rotation of the support body 61 is stopped, and the first cover rubber 43 is cut by cutting means (not shown). Thereafter, the roller 65 is separated from the surface to finish the pasting operation, but the rear end portion of the cut first cover rubber 43 is pressed by the roller 65 and joined to the front end portion.

  When the first cover rubber 43 is affixed as described above, as shown in FIG. 5C, a substantially annular rubber layer joined to the outer surface of the sidewall portion 3 of the green tire 55 by one joint portion 43 </ b> A. Is formed. The tire molding device 60 attaches the first cover rubber 43 to the surface of the ribbon-like rubber 42G on which the laminated portions 42 are laminated in this way, and forms the different colored rubber layer 41 for forming the different colored portions 40. Subsequently, a black second cover rubber 44 is similarly applied to at least the entire surface of the first cover rubber 43, and the entire surface of the different color rubber layer 41 is covered with the black second cover rubber 44. Next, when the other sidewall portion 3 also has the different color portion 40, the green tire 55 is turned and the like, and the cover rubbers 43 and 44 are attached in a similar manner to complete the molding of the green tire 55.

  Thereafter, the green tire 55 is removed from the tire molding device 60 and conveyed to a vulcanization molding device by a conveying device (not shown), and vulcanized and molded in the mold to produce a pneumatic tire 1 having a predetermined shape. Is done. In this vulcanization molding process, as in the conventional pneumatic tire 100 (see FIG. 7), the green tire 55 is accommodated in a mold in which a portion corresponding to the different-colored portion 40 is recessed, and vulcanized. The part which forms and forms the different color part 40 of the pneumatic tire 1 (sidewall part 3) after vulcanization molding is protruded from other parts. The surface of the protruding portion is ground by buffing or the like in the next step to remove at least the second cover rubber 44 in that portion, and a different color rubber layer 41 made of white rubber is applied to the outer surface of the sidewall portion 3. The different color portion 40 is formed by exposure.

  As described above, in the present embodiment, since the first cover rubber 43 having the same color is provided on the surface (outer surface) of the laminated portion 42 made of ribbon-like rubber 42G of different colors such as white, the different color rubber layer 41 Unevenness formed on the surface can be reduced. That is, at the molding stage of the green tire 55, the concave portion due to the step or the like of the ribbon-like rubber 42G on which the first cover rubber 43 is laminated enters into the concave portion, so that the surface unevenness can be reduced. At the same time, in the vulcanization molding stage, the first cover rubber 43 flows so as to fill the unevenness of the surface of the laminated portion 42, so that the surface of the different color rubber layer 41 after the vulcanization molding becomes more gentle. can do. As described above, since the unevenness on the surface of the different color rubber layer 41, which is particularly prone to the occurrence of Chris due to the unevenness, is reduced, it is possible to suppress the occurrence of Chris on the surface of the different color rubber layer 41 after vulcanization molding. Can do. As a result, it is possible to suppress the generation of cracks on the surface of the different color rubber layer 41 with Chris as a nucleus, and the crack durability of the sidewall portion 3 of the pneumatic tire 1 can be improved.

Further, in the pneumatic tire 1, the winding end 20C of the carcass 20 is disposed on the outer side in the tire radial direction of the stacking portion 42, and the stepped portion sandwiching the winding end 20C is positioned outside the stacking portion 42. And the unevenness | corrugation of the surface of the different color rubber layer 41 can prevent reliably that it becomes large under the influence of the level | step difference of 20 C of winding ends. In addition, in this pneumatic tire 1, the unevenness of the surface of the different color rubber layer 41 serving as a base before the second cover rubber 44 is pasted can be reduced when the green tire 55 is molded, and also during the vulcanization molding. Since the unevenness can be further reduced, thickness unevenness due to the location of the second cover rubber 44 can be reduced. As a result, the ratio H (T ₁ / T ₂ ) of the thickness T ₁ of the thickest portion to the thickness T ₂ of the thinnest portion of the second cover rubber 44 (see FIG. 3) is 1.0 to 1.3. The surface strength such as the thickness and tension can be made uniform.

  Here, the ribbon-like rubber 42G of the laminated portion 42 has an angle of 10 to 40 ° (an angle θ shown in FIG. 2) with respect to the carcass 20 at each laminated position when viewed in a cross section in the tire width direction. It is desirable to laminate along the winding part 20B. By laminating in this way, the surfaces of the respective ribbon-like rubbers 42G at the time of lamination are smoothly connected to each other, and the unevenness of the surface of the laminated portion 42 can be further alleviated. On the other hand, when the angle θ is larger than 40 °, the unevenness on the surface of the laminated portion 42 becomes large, and even if the first cover rubber 43 is provided on the surface, the unevenness may not be sufficiently relaxed. On the other hand, when the angle θ is smaller than 10 °, it is necessary to laminate the ribbon-like rubber 42G over a plurality of times (layers) in order to form the laminated portion 42, and the manufacturing efficiency is reduced. There is a fear.

  When the thickness of the first cover rubber 43 is thinner than 0.4 mm, the thickness and the amount of rubber of the first cover rubber 43 are insufficient with respect to the size of the irregularities on the surface of the laminated portion 42. However, there is a possibility that the effect of relaxing the unevenness cannot be obtained sufficiently. On the other hand, when the thickness is larger than 1.2 mm, the flexibility of the first cover rubber 43 is lowered, and deformation corresponding to the unevenness of the surface of the laminated portion 42 becomes difficult, and the recess cannot be filled. Air may remain between the members. Therefore, it is desirable that the thickness of the first cover rubber 43 is 0.4 to 1.2 mm.

  In the present embodiment, the cover rubbers 43 and 44 are formed by sticking a sheet-like rubber along the circumferential direction of the sidewall portion 3. For example, the cover rubbers 43 and 44 are formed in an annular shape from an unvulcanized rubber sheet. Others such as those cut out may be used. Further, in this pneumatic tire 1, the cover rubbers 43 and 44 are arranged in two layers, one in total. However, these may be arranged in one or more layers and arranged in three or more layers. Further, the ribbon-like rubbers 50 and 42G may be formed of long rubber members formed in accordance with the formation of the respective rubber members, such as a cross-sectional curved shape, a substantially crescent shape, and a triangular shape, in addition to the rectangular shape of the present embodiment. Use it.

(Tire test)
In order to confirm the effect of the present invention, as described above, the pneumatic tire 1 (hereinafter referred to as an “executed product”) of the embodiment in which the sidewall portion 3 (see FIGS. 1 and 2) is formed, and the different color rubber layer 41 thereof. Two different types of pneumatic tires (hereinafter referred to as comparative products 1 and 2) and conventional pneumatic tires (hereinafter referred to as conventional products), which were formed differently, were manufactured under the following conditions. A sex test was performed. The implemented product, the comparative product, and the conventional product are all radial ply tires for passenger cars having a tire size of 265 / 70R16-112S defined by JATMA YEAR BOOK (2006, Japan Automobile Tire Association Standard).

  The durability test was carried out using a drum tester equipped with a drum having a smooth surface, with each tire mounted on an 8J-16 rim, adjusted to an internal pressure of 100 kPa lower than the specified internal pressure. The test is so-called to run (rotate) on the drum at the same predetermined speed until a failure (crack) occurs in the tire (sidewall portion 3) in a state where each tire is pressed against the drum and a load of 1120 kgf is applied. This is a low internal pressure Rongrand ram test. In addition, the test results were compared and evaluated by measuring the distance traveled until each tire failed.

Table 1 shows the structure of the different color rubber layer 41 of each tire and the test results.
In Table 1, “lamination angle θ of the ribbon-like rubber” is an angle θ of the ribbon-like rubber 42G with respect to the carcass 20B at the above-described lamination position (see FIG. 2). Further, the “stacked portion upper end position A” and “carcass winding end position B” are respectively the tire radial outer end of the stacked portion 42 and the rolled end 20C of the carcass 20 positioned on the outer side in the tire radial direction from them. This is the distance in the tire radial direction from the maximum width position 6 (see FIG. 1). The “positional relationship between the stacking portion and the carcass winding end” is “up” when the winding end 20C of the carcass 20 is positioned on the outer side in the tire radial direction with respect to the outer end in the tire radial direction of the stacking portion 42. Time is expressed as “below”. The “thickness ratio H of the second cover rubber” is the ratio H (T ₁ / T ₂ ) of the thickness T ₁ of the thickest portion to the thickness T ₂ of the thinnest portion of the second cover rubber 44 described above. (See FIG. 3). The “low-pressure long ground ram result” is a test result (travel distance) measured for each tire, and the “crack occurrence position” indicates where the crack occurred in each tire.

  As shown in Table 1, in the implemented product, the different color rubber layer 41 was provided with a first cover rubber 43 of 0.8 mm, and the ribbon-like rubber 42G of the laminated portion 42 was laminated at a lamination angle θ of 35 °. Further, the upper end position A of the laminated portion 42 was set to 15 mm, the position B of the winding end 20C of the carcass 20 was set to 12 mm, and the winding end 20C was disposed above. Furthermore, in the embodiment, the thickness ratio H of the second cover rubber 44 was 1.05.

  In the comparative product 1, a 0.8 mm first cover rubber 43 is provided on the different color rubber layer 41 as in the implementation product, but the ribbon-like rubber 42G of the laminated portion 42 is laminated at a lamination angle θ of 55 °, Further, the upper end position A of the laminated portion 42 was 10 mm, the position B of the winding end 20C of the carcass 20 was 12 mm, and the winding end 20C was disposed below. Further, in the comparative product 1, the thickness ratio H of the second cover rubber 44 was 1.1.

  In the comparative product 2, a 0.8 mm first cover rubber 43 is provided on the different color rubber layer 41 and the ribbon-like rubber 42G of the laminated portion 42 is laminated at a lamination angle θ of 35 ° in the same manner as the implementation product. The upper end position A of the portion 42 is 10 mm, the position B of the winding end 20C of the carcass 20 is 12 mm, and the winding end 20C is disposed below. Further, in the comparative product 2, the thickness ratio H of the second cover rubber 44 was 1.05.

  Unlike the actual product and the comparative products 1 and 2, the conventional product did not have the first cover rubber 43. However, like the comparative product 1, the ribbon-shaped rubber 42G of the laminated portion 42 was formed at a lamination angle θ of 55 °. The upper end position A of the stacked portion 42 was 10 mm, the position B of the winding end 20C of the carcass 20 was 12 mm, and the winding end 20C was disposed below. In the conventional product, the thickness ratio H of the second cover rubber 44 is 1.5.

  As a result of testing each of these tires, cracks occurred in the different color rubber layer 41 in all tires, but the traveling distance was 10000 km for the comparative product 1 and 13,000 km for the comparative product 2 with respect to 5000 km of the conventional product. Was also long. On the other hand, the travel distance of the implemented product is 15000 km, 3 times that of the conventional product, and longer than both comparative products 1 and 2. It was found that the distance became extremely long and the crack durability of the sidewall portion 3 was greatly improved.

  From the above results, it is proved that the present invention can suppress the occurrence of chris on the surface of the different color rubber layer 41 forming the different color part 40 of the pneumatic tire 1 and improve the crack durability of the sidewall part 3. It was.

1 is a half cross-sectional view in the tire width direction schematically showing the overall structure of a pneumatic tire of an embodiment. It is sectional drawing which expands and shows typically the X area vicinity of FIG. FIG. 3 is a cross-sectional view schematically showing an enlarged vicinity of a Y region in FIG. 2. It is a side view which shows typically the principal part of the tire shaping | molding apparatus for shape | molding the green tire of this embodiment. It is a perspective view showing typically the state where the 1st cover rubber is stuck on the surface of one side wall part of a green tire. It is a perspective view which shows typically a part of outer surface of the side wall part in which the different color part of the conventional pneumatic tire was formed. It is a schematic diagram which shows the procedure which forms a white rubber part in the outer surface of the sidewall part of the pneumatic tire of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Bead part, 2A ... Bead outer surface rubber, 3 ... Side wall part, 4 ... Tread part, 5 ... Shoulder part, 10 ... Canvas Chafer, 11 ... Bead core, 12 ... Bead filler, 13 ... Tread rubber, 14 ... Belt layer, 15 ... Belt layer, 16 ... Belt reinforcement layer, 17 ... Belt under Cushion rubber, 20 ... carcass, 20A ... main body, 20B ... winding part, 20C ... winding end, 21 ... carcass ply, 22 ... carcass ply, 30 ... upper side Wall rubber, 31 ... lower side wall rubber, 32 ... intermediate side wall rubber, 40 ... different color part, 41 ... different color rubber layer, 42 ... laminated part, 42G ... ribbon shape Rubber, 2K ... interface, 43 ... first cover rubber, 44 ... second cover rubber, 50 ... ribbon rubber, 55 ... green tire, 60 ... tire molding apparatus, 61 ... Support, 62 ... Extruder, 62A ... Base, 63 ... Roller, 64 ... Roller, 65 ... Roller, CL ... Equatorial plane, TE ... Tread end.

Claims (7)

A carcass extending between the pair of bead cores, folded around the bead core from the inside to the outside of the tire and wound up to the sidewall portion toward the outside in the radial direction of the tire, and another portion on the outer surface of the sidewall portion. It is a pneumatic tire provided with different color parts of different colors,
A laminated portion formed by laminating ribbon-like rubber of the same color as the different color portion, and disposed on the outer surface side of the wound carcass of the sidewall portion, and the different color portion provided on the outer surface of the laminated portion A different color rubber layer made of a first cover rubber of the same color and forming the different color part;
A second cover rubber of the same color as the other part covering the outer surface of the different color rubber layer other than the different color part,
The pneumatic tire according to claim 1, wherein a winding end of the carcass is disposed on an outer side in the tire radial direction of the laminated portion. In the pneumatic tire according to claim 1,
The ribbon-like rubber of the laminated portion is laminated along the rolled up carcass and is laminated at an angle of 10 to 40 ° with respect to the carcass at each lamination position when viewed in the cross section in the tire width direction. Pneumatic tire characterized by. In the pneumatic tire according to claim 1 or 2,
The pneumatic tire according to claim 1, wherein a thickness of the first cover rubber is 0.4 to 1.2 mm. In the pneumatic tire according to any one of claims 1 to 3,
The pneumatic tire according to claim 2, wherein the ratio of the thickness of the thickest part to the thickness of the thinnest part is in a range of 1.0 to 1.3. A carcass extending between the pair of bead cores, folded around the bead core from the inside to the outside of the tire and wound up to the sidewall portion toward the outside in the radial direction of the tire, and another portion on the outer surface of the sidewall portion. A method of manufacturing a pneumatic tire provided with different color different color parts,
Laminating a ribbon-like rubber of the same color as the different color portion along the winding portion excluding the winding end of the carcass;
Attaching a first cover rubber of the same color as the different color part to the surface of the laminated ribbon-like rubber to form a different color rubber layer for forming the different color part;
Applying a second cover rubber of the same color as that of the other part to the surface of the first cover rubber to cover the surface of the different color rubber layer;
The manufacturing method of the pneumatic tire characterized by having. In the manufacturing method of the pneumatic tire according to claim 5,
The step of laminating includes laminating the ribbon-like rubber so as to form an angle of 10 to 40 ° with respect to the wound carcass at each laminating position when viewed in a cross section in the tire width direction. A method for manufacturing a tire. In the manufacturing method of the pneumatic tire according to claim 5 or 6,
A method for manufacturing a pneumatic tire, wherein the thickness of the first cover rubber is 0.4 to 1.2 mm.

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