WO2014174755A1

WO2014174755A1 - Tire

Info

Publication number: WO2014174755A1
Application number: PCT/JP2014/001561
Authority: WO
Inventors: 聡徳武
Original assignee: 株式会社ブリヂストン
Priority date: 2013-04-24
Filing date: 2014-03-18
Publication date: 2014-10-30
Also published as: JP2014213688A; JP6035194B2

Abstract

The purpose of the present invention is to improve the anti-cracking properties of a tire having a decorative section on a side wall section. A reinforced rubber layer (13) is disposed further inward in the tire width direction than a stain prevention rubber layer (11a), and a tire radial direction outermost edge (13a) of the reinforced rubber layer (13) is positioned further outward in the tire radial direction than a tire radial direction outermost edge (11d) of the stain prevention rubber layer (11a) or further inward in the tire width direction than a tire width direction outermost edge (7a) of a belt layer (7). A tire radial direction innermost edge (13b) of the reinforced rubber layer (13) is positioned further inward in the tire radial direction than a tire radial direction innermost edge (11e) of the stain prevention rubber layer (11a).

Description

tire

According to the present invention, a contamination preventing rubber layer not containing an anti-aging agent is provided on at least a part of the sidewall portion, and a decorative portion is provided adjacent to the contamination preventing rubber layer and exposed on the outer surface of the sidewall portion. It is related to tires.

Tires with a decorative part formed on the side part of the tire are widely used. In such a tire, as described in Patent Document 1, the anti-aging agent contained in the surrounding rubber oozes out to prevent the decorative portion from being contaminated and discolored. There is known a technique in which a non-contaminating antifouling rubber layer that is not contained is disposed to isolate the decorative part from the side wall rubber containing the anti-aging agent.

JP-A-4-121205

By the way, in order to improve the visibility of the decorative portion, it is preferable to dispose the decorative portion and the pollution prevention rubber layer on the outer side in the tire radial direction from the tire maximum width position Pw shown in FIG.
On the other hand, the state of distortion (deformation) of the sidewall portion of the tire during the rolling load of the tire is exaggerated and shown in phantom in FIG. As shown in FIG. 4, the amount of tire distortion during load rolling peaks near the tire maximum width position Pw and decreases toward the inside in the tire radial direction from the tire maximum width position Pw. Therefore, if an attempt is made to dispose the anti-contamination rubber layer up to the vicinity of the tire maximum width position where the distortion is large, a large stress is applied near the adhesion interface between the anti-contamination rubber layer and another rubber layer, There was a concern that cracks are likely to occur. The generated crack may extend to the decorative portion, and in that case, the decorativeness may be impaired.

In recent years, tires have been flattened in order to improve cornering performance, and there has been an increasing demand for a decorative portion on large diameter tires. In these tires, the distortion generated in the sidewall portion becomes larger, and the above-mentioned concerns become more remarkable.

An object of the present invention is to provide a technique for improving crack resistance in a tire provided with a decorative portion in a sidewall portion. .

The tire according to the present invention includes a bead core embedded in each of the pair of bead portions, a main body portion extending in a toroid shape from the tread portion to the bead portion via the sidewall portion, and continuous with the main body portion around the bead core. One or more carcass plies each having a folded portion formed by folding, and at least one belt layer that is positioned on the outer peripheral side of the crown portion of the carcass ply and is made of rubber covered with a cord. The tire is provided with a contamination-preventing rubber layer that does not contain an anti-aging agent, and a decorative portion that is adjacent to the contamination-preventing rubber layer and exposed on the outer surface of the sidewall portion, and at least the contamination A reinforcing rubber layer is disposed on the inner side in the tire width direction of the prevention rubber layer, and the outermost end in the tire radial direction of the reinforcement rubber layer is disposed on the contamination prevention rubber. The tire radial direction outermost end of the tire layer in the tire radial direction or the tire width direction innermost end of the belt layer in the tire width direction inner side, and the tire radial direction innermost end of the reinforcing rubber layer, The anti-contamination rubber layer is located on the inner side in the tire radial direction than the innermost end in the tire radial direction.

In this specification and claims, the position and dimensions of the reinforcing rubber layer, such as the outermost radial position of the tire in the radial direction, unless otherwise specified, the tire is mounted on the applicable rim and filled with a predetermined internal pressure. It shall be measured in the state.
Here, the “applicable rim” is a rim in which an industrial standard effective for the region where the tire is produced or used is determined for each tire, and if it is JATMA (Japan Automobile Tire Association), a standard rim, If it is TRA (THE TIRE and RIM ASSOCIATION INC.), It will be "Design Rim", and if it is ETRTO (European Tire and Rim Technical Organization), it will be "Measuring RIM".
In addition, the “predetermined internal pressure” refers to the filling air pressure (maximum air pressure) corresponding to the maximum load capacity of the tire, which is defined according to the tire size in the above-mentioned industrial standard, and the “maximum load capacity” refers to the above The maximum mass allowed to be applied to a tire in the industry standard.
By the way, the air here can be replaced with nitrogen gas or other inert gas.

According to the tire of the present invention, it is possible to improve the crack resistance without impairing the visibility of the tire provided with the decorative portion in the sidewall portion.

1 is a cross-sectional view in the tire width direction of a tire half portion showing a tire according to an embodiment of the present invention in a no-load posture assembled with an applied rim and filled with a predetermined internal pressure. It is a tire width direction sectional view of the tire half which shows the 1st modification of a tire of one embodiment of this invention. It is a tire width direction sectional view of the tire half which shows the 2nd modification of a tire of one embodiment of this invention. FIG. 3 is a cross-sectional view in the tire width direction of a tire half portion, exaggeratingly illustrating a deformation mode of an outer surface of a sidewall portion during load rolling of the tire.

Embodiments of the present invention will be described below with reference to the drawings.
In addition, the following description is an illustration to the last, and a structure, an effect, etc. of each member are not limited to this.
FIG. 1 is a cross-sectional view in the tire width direction of a tire half portion showing a tire 10 according to an embodiment of the present invention in an unloaded posture in which the tire 10 is assembled to an applicable rim R and filled with a predetermined internal pressure. The tire 10 includes a bead core 4 embedded in each of the pair of bead portions 3, a main body portion 6a extending in a toroidal shape from the tread portion 1 through the sidewall portion 2 to the bead portion 3, and the main body portion 6a. , One or more carcass plies 6 each having a folded portion 6b folded around the bead core 4, and at least one layer (here, three layers) positioned on the outer peripheral side of the crown portion of the carcass ply 6 and coated with rubber. ) Belt layer 7. Steel cords are embedded in the two intersecting belt layers on the inner side in the tire radial direction indicated by a solid line, and the cords extend while being inclined at a substantially constant angle with respect to the tire circumferential direction. Further, the cord of the crossing belt on the inner side in the tire radial direction and the cord of the crossing belt on the outer side in the tire radial direction extend inclining in directions opposite to each other with respect to the tire circumferential direction. An organic fiber cord is embedded in the circumferential belt layer on the outer side in the tire radial direction indicated by the dotted line and the alternate long and short dash line, and the cord extends spirally in the tire circumferential direction. The circumferential belt layer can be formed by, for example, winding a rubber-coated cord.

Antifouling rubber layers

11a and 11b that do not contain an anti-aging agent are disposed on the outer surface of the carcass ply 6 on the tire. A pollution prevention rubber layer 11a extending from the outer surface of the bead part 3 to the inner side in the tire radial direction of the belt layer 7 of the tread part 1 is molded as a part of the raw tire, and the pollution prevention rubber located outside the tread part 1 in the tire width direction. The layer 11b is molded as a part of the tread rubber and attached to the green tire. In this specification and claims, the tire outer surface side and the inner surface side of the carcass ply refer to the sides facing the outer space and inner space (inner cavity filled with air) of the tire, respectively. To do. In this way, by adopting a configuration in which the entire side rubber located outside the sidewall portion is used as the anti-contamination rubber layer 11a, it becomes easy to expose the anti-contamination rubber layer 11b to the outer surface of the tire, and to the vicinity of the tread portion. It is possible to easily manufacture a tire using a pollution-preventing rubber layer.
The decorative portion 12 is adjacent to the contamination-preventing rubber layer 11 a and exposed on the outer surface of the sidewall portion 2. An anti-aging agent is contained in the

rubber layers

21a and 21b adjacent to the anti-contamination rubber layer 11a in the tire radial direction. The decorative portion 12 is separated from the

rubber layers

21a and 21b by the contamination

prevention rubber layers

11a and 11b.
In addition, although illustration is abbreviate | omitted, the contamination prevention rubber layer 11b does not exist and the whole tread rubber can also be made to contain an anti-aging agent.

The decorative portion 12 can be formed, for example, by jetting a paint containing ink from the head of an inkjet printer onto the surface of the anti-pollution rubber layer 11a of the tire after vulcanization molding and printing on the surface. it can. At this time, printing can also be performed between the anti-contamination rubber layer 11a via a primer. The decorative portion 12 can also be formed by stacking a plurality of types of paint. Moreover, the decoration part 12 can also be comprised with colored rubber. In addition, the decoration part 12 can be made into arbitrary colors. Preferably, the decorative portion 12 is formed by printing from the viewpoint of cost or the like.
Although illustration is omitted, the decoration portion 12 can form a mark made up of characters, figures, symbols including a barcode, and other patterns, for example, in the tire circumferential direction.

Next, although the component mix | blended with the rubber composition for general tires can be mix | blended suitably with the rubber composition which forms a pollution prevention rubber layer, anti-aging agent is not contained. That is, the contamination-preventing rubber layer means a rubber layer that does not contain an anti-aging agent and at least does not contaminate the decorative portion adjacent to the anti-aging agent.
By forming the anti-contamination rubber layer from such a rubber composition, the

anti-contamination rubber layers

11a and 11b containing no anti-aging material are isolated between the decorative portion 12 and the

rubber layers

21a and 21b, The decorative part 12 can be effectively prevented from contamination.
As the rubber component of the pollution prevention rubber layer, natural rubber (NR), butyl rubber (IIR), halogenated butyl rubber, isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), Acrylonitrile butadiene rubber (NBR), ethylene propylene diene terpolymer (EPDM) or the like can be blended alone or in combination of two or more. In addition, when the ethylene propylene diene terpolymer is blended in the pollution prevention rubber layer, the proportion of the ethylene propylene diene terpolymer in the pollution prevention rubber layer is preferably 20 parts by weight in 100 parts by weight of the rubber component. Part by weight or more, more preferably 80 parts by weight or more.

In addition, by including butyl rubber in at least a part of the contamination preventing

rubber layers

11a and 11b, the permeation of the anti-aging agent in the contamination preventing rubber layer is reduced, and the aging prevention contained in the

rubber layers

21a and 21b is prevented. Contamination of the decorative part 12 with the agent can be prevented more effectively.

Next, in the modification shown in FIG. 2, among the side rubber, the region 11 a adjacent to the decorative portion 12 and the surrounding region 11 a is a contamination-preventing rubber layer containing butyl rubber, and the other region 11 c of the side rubber is used. The normal rubber contains anti-aging material. Since the contamination-preventing rubber layer containing butyl rubber can more effectively reduce the permeation of the anti-aging agent, the contamination of the decorative portion 12 can be prevented even if only the region 11a is used as the contamination-preventing rubber layer, not the entire side rubber. It can be sufficiently suppressed.
When the contamination preventing rubber layer further contains an inorganic clay mineral in the region, the permeation of the anti-aging agent in the contamination preventing rubber layer is further reduced, and the contamination preventing effect of the decorative portion 12 by the rubber layers 11c and 21b is improved. It can be further increased.

As shown in FIG.1 and FIG.2, in the tire 10 of this embodiment, the crescent-shaped reinforcement rubber layer 13 is arrange | positioned by the cross section of a tire width direction which covers the pollution prevention rubber layers 11a and 11b inside a tire width direction. The outermost end 13a in the tire radial direction of the reinforcing rubber layer 13 is positioned on the inner side in the tire width direction of the outermost end 7a in the tire width direction of the belt layer 7, and the innermost end in the tire radial direction of the reinforcing rubber layer 13 13b is located on the inner side in the tire radial direction than the innermost end 11e in the tire radial direction of the contamination preventing rubber layer 11a.
Thus, by arranging the reinforcing rubber layer having a sufficient length in the tire radial direction on the sidewall portion, the distortion of the sidewall portion during load rolling can be reduced, and the embodiment shown in FIG. Then, it is possible to suppress the application of a large stress in the vicinity of the adhesion boundary surface between the contamination prevention rubber layer 11a and the rubber layers 21a and 21b and in the vicinity of the adhesion boundary surface between the contamination prevention rubber layer 11b and the rubber layer 21b. In the embodiment shown in FIG. 2, a large stress is applied in the vicinity of the adhesion boundary surface between the contamination prevention rubber layer 11a and the rubber layer 11c and in the vicinity of the adhesion boundary surface between the contamination prevention rubber layer 11b and the rubber layers 11c and 21b. Can be suppressed. Therefore, in the embodiment shown in FIG. 1 and FIG. 2, cracks at these adhesion boundary surfaces can be prevented, and the crack resistance of the contamination preventing

rubber layers

11a and 11b can be effectively improved.

For example, in a large-diameter tire or a flat tire, distortion at the time of load rolling becomes large, so that it is difficult to dispose the rubber layer 11c to the vicinity of the belt layer 7.
Here, as shown in FIG. 3, the outermost end 13a in the tire radial direction of the reinforcing rubber layer 13 is positioned on the outer side in the tire radial direction from the outermost end 11d in the tire radial direction of the anti-contamination rubber layer 11a. The tire radial direction innermost end 13b of the reinforcing rubber layer 13 is positioned at the inner side in the tire width direction of the tire width direction outermost end 7a of the tire, and the tire diameter in the tire radial direction of the contamination preventing rubber layer 11a is larger than the tire radial direction innermost end 11e. By positioning the inner side in the direction, it is possible to sufficiently reduce the distortion of the sidewall portion at the time of load rolling, and it is possible to more effectively improve the crack resistance of the contamination preventing rubber layer 11a.
In this embodiment, the region 11c other than the side rubber contamination prevention rubber layer 11a is a rubber layer containing a normal anti-aging material.

In the embodiment shown in FIGS. 1 to 3, the reinforcing rubber layer 13 is disposed on the inner surface side of the carcass ply 6.
As described above, the reinforcing rubber layer 13 is positioned on the compression side (that is, the inner side in the tire width direction) from the neutral axis of the bending at the time of rolling of the tire, and functions as a tension member, so that the sidewall portion 2 Strain can be effectively suppressed, and the crack resistance of the contamination-preventing rubber layer can be further improved.

Here, as shown in FIGS. 1 to 3, the maximum thickness T of the reinforcing rubber layer 13 is twice the maximum thickness t from the outer surface of the carcass ply 6 to the outer surface of the sidewall portion 2 in the tire width direction cross section. The above is preferable. Thereby, the rigidity of the sidewall portion can be sufficiently ensured in the region where the strain is maximized, and the crack resistance of the pollution prevention rubber layer can be further effectively improved. In addition, it is preferable to appropriately design the maximum thickness T of the reinforcing rubber layer 13 so that the maximum distortion of the outer surface of the sidewall portion 2 is, for example, 13% or less. The reason for suppressing the maximum strain on the outer surface of the sidewall portion in this way is that it is difficult to provide a contamination-preventing rubber layer at a location where the strain on the outer surface of the sidewall portion is large from the viewpoint of crack resistance. .
On the other hand, from the viewpoint of ensuring ride comfort, suppressing an increase in rolling resistance, and ensuring various performances, the maximum thickness T of the reinforcing rubber layer 13 is increased from the outer surface of the carcass ply 6 to the sidewall in the cross section in the tire width direction. The maximum thickness t up to the outer surface of the portion 2 is preferably 2.5 times or less.
Further, from the viewpoint of suppressing the distortion of the sidewall portion 2, it is preferable to reduce the thickness t, for example, t is preferably 3 mm or less.
Here, the thickness of the reinforcing rubber layer 13 is measured in the direction of the normal line standing on the tire inner surface of the reinforcing rubber layer 13 in the cross section in the tire width direction. The maximum value of the thickness of the reinforcing rubber layer 13 measured in this way is defined as the maximum thickness T of the reinforcing rubber layer 13. The thickness from the outer surface of the carcass ply 6 to the outer surface of the sidewall portion 2 is measured in the direction of the normal line standing on the outer surface of the carcass ply 6 in the tire width direction cross section. 1 to 3, the thickness of the decorative portion 12 is not included in the thickness from the outer surface of the carcass ply 6 to the outer surface of the sidewall portion 2. The maximum value of the thickness from the outer surface of the carcass ply 6 to the outer surface of the sidewall portion 2 measured in this way is defined as the maximum thickness t from the outer surface of the carcass ply 6 to the outer surface of the sidewall portion 2.

Further, from the viewpoint of effectively improving the visibility of the decorative portion by arranging the decorative portion in a conspicuous position, the outermost end 12a in the tire radial direction of the decorative portion 12 is located on the outer side in the tire radial direction from the maximum tire width position Pw. It is preferable to arrange in. If the conventional reinforcing rubber is not arranged, distortion increases in the tire radial direction outside the tire maximum width position, so placing the decorative part in that area has a problem with the durability of the decorative part Further, since the distortion is reduced by the arrangement of the reinforcing rubber 13, durability can be ensured even if the decorative portion 12 is arranged to the outer side in the tire radial direction from the tire maximum width position Pw.

Further, any combination of the end portion of the tread rubber 21b, the end portion of the pollution prevention rubber layer 11a, and the end portion of the side rubber 11b (when the side rubber 11b is provided as shown in FIGS. 1 and 2) (FIG. 2). Then, it is preferable that the shortest linear distance between the end portions of the anti-contamination rubber layer 11a and the end portion of the tread rubber 21b is at least 10 mm. When these end portions are concentrated (adjacent), strain is concentrated at the interface of the rubber layer and cracks are likely to be generated. Therefore, the durability can be maintained at a high level by providing a space of 10 mm or more between the end portions. More preferably, all of the end portion of the tread rubber, the end portion of the contamination prevention layer, and the end portion of the side rubber are separated by 10 mm or more.

In addition, if the folded end of the carcass ply is positioned in the tire radial direction between the outermost end in the tire radial direction and the innermost end in the tire radial direction of the decorative portion, distortion tends to concentrate on the end of the ply. It tends to lead to peeling or cracking of the part. In this case, the crack resistance at the adhesive interface of the rubber also decreases. For this reason, the ply end 6e is positioned on the inner side in the tire radial direction than the innermost end 12b in the tire radial direction of the decorative portion 12, or on the outer side in the tire radial direction than the outermost end 12a in the tire radial direction of the decorative portion. The durability of the part and the crack resistance of the adhesive interface of the rubber can be improved. More preferably, the ply end 6e is arranged so as not to contact the anti-contamination rubber.
Further, the elastic modulus of the anti-staining rubber layer is preferably 80% or less, more preferably 70% or less of the elastic modulus of the reinforcing rubber layer. In this case, the durability of the tire can be further improved by causing the reinforcing rubber to bear most of the distortion of the sidewall portion.
This elastic modulus was calculated by a method according to JIS K6251, that is, by measuring dynamic stress when dynamic strain was applied under conditions of room temperature 20 ° C., strain 2%, and predetermined frequency. 100% modulus is meant.

In the above-described embodiment, the configuration of the present invention is applied to the half portion on one side of the tire, in particular, the half portion on the outside of the vehicle, but the configuration of the present invention can also be applied to both sides of the tire.

Example tires and comparative example tires having a tire size of 255 / 35ZR19 were made as prototypes and their performance was evaluated, which will be described below.

As shown in FIG. 1, both the example tires and the comparative example tires have side wall portions 2 that are adjacent to the anti-contamination rubber layers 11a and 11b and the anti-contamination rubber layers 11a and 11b. The decorative part 12 exposed on the outer surface of the part 2 and an anti-aging agent are contained, and the rubber layers 21a and 21b adjacent to the inside and outside of the anti-contamination rubber layers 11a and 11b in the tire radial direction are disposed.

Here, the ratio T / t between the maximum thickness T of the reinforcing rubber layer and the maximum thickness t from the outer surface of the carcass ply to the outer surface of the sidewall portion in each of the tires of the examples and the comparative examples, and the carcass Whether the folded end of the ply is positioned between the outermost end in the tire radial direction and the innermost end in the tire radial direction in the tire radial direction (hereinafter referred to as “overlap of the folded end of the carcass ply and the decorated portion” Table 1 shows the presence or absence.

Further, in all of the tires of Examples, the reinforcing rubber layer 13 is disposed on the inner surface side of the carcass ply 6. On the other hand, the comparative example tire 1 is not provided with a reinforcing rubber layer.

<Crack resistance evaluation test>
Example tires and comparative example tires were filled with a predetermined internal pressure of JATMA standard, the maximum load capacity of JATMA standard was loaded, a drum test was performed over 10,000 km, and an adhesion boundary between a pollution control rubber layer and another rubber layer The crack resistance was evaluated by the total length of cracks generated on the surface. The results are shown in Table 1. The reciprocal of the total length of cracks in the comparative example tire 1 is 100. The higher the value, the better the crack resistance.

From Table 1, it was revealed that all of the example tires had better crack resistance than the comparative example tires. Further, in the tire width direction cross section, the

example tires

1, 2, and 4 in which the maximum thickness of the reinforcing rubber layer is more than twice the maximum thickness from the outer surface of the carcass ply to the outer surface of the sidewall portion are crack resistant. It became clear that the sex was greatly improved.

1: tread part, 2: sidewall part, 3: bead part,
4: Bead core, 6: Carcass ply,
6a: carcass ply body,
6b: the folded portion of the carcass ply,
6e: folded end of the carcass ply, 7: belt layer,
7a: outermost end in the tire width direction of the belt layer, 10: tire,
11a: Antifouling rubber layer, 11b: Antifouling rubber layer,
11c: a rubber layer containing an anti-aging material,
11d: the outermost end in the tire radial direction of the pollution preventing rubber layer,
11e: the innermost end in the tire radial direction of the anti-contamination rubber layer, 12: a decorative part,
12a: the outermost end in the tire radial direction of the decorative part,
12b: innermost end in the tire radial direction of the decorative part,
13: Reinforcing rubber layer, 13a: Outermost end in the tire radial direction of the reinforcing rubber layer,
13b: innermost end in the tire radial direction of the reinforcing rubber layer, 21a, 21b: rubber layer,
Pw: Tire maximum width position

Claims

A bead core embedded in each of the pair of bead parts, a main body part extending in a toroid form from the tread part through the sidewall part to the bead part, and a folded part formed by being folded around the bead core continuously to the main body part. Comprising one or more carcass plies having at least one belt layer located on the outer peripheral side of the crown portion of the carcass ply and having a cord covered with rubber;
A tire in which a contamination prevention rubber layer not containing an anti-aging agent is provided on at least a part of the sidewall portion, and a decorative portion is provided adjacent to the contamination prevention rubber layer and exposed on the outer surface of the sidewall portion. Because
A reinforcing rubber layer is disposed at least on the inner side in the tire width direction than the anti-contamination rubber layer,
The outermost end in the tire radial direction of the reinforcing rubber layer, the outer side in the tire radial direction than the outermost end in the tire radial direction of the anti-contamination rubber layer, or the inner side in the tire width direction from the outermost end in the tire width direction of the belt layer; As well as
A tire characterized in that the innermost end in the tire radial direction of the reinforcing rubber layer is located on the inner side in the tire radial direction from the innermost end in the tire radial direction of the anti-contamination rubber layer.
The tire according to claim 1, wherein the reinforcing rubber layer is disposed on the inner surface side of the carcass ply.
The tire according to claim 2, wherein the maximum thickness of the reinforcing rubber layer is at least twice the maximum thickness from the outer surface of the carcass ply to the outer surface of the sidewall portion in a cross section in the tire width direction.
The tire according to any one of claims 1 to 3, wherein an outermost end in the tire radial direction of the decorative portion is arranged on the outer side in the tire radial direction from the position of the maximum tire width.
The folded end of the carcass ply is located on the inner side in the tire radial direction than the innermost end in the tire radial direction of the decorative part, or on the outer side in the tire radial direction of the outermost end in the tire radial direction of the decorative part. Item 5. The tire according to any one of Items 1 to 4.