JP2015112986A - Pneumatic tire, run flat tire and production method of them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving heat radiation and suppressing occurrence of crack for improving durability.SOLUTION: A pneumatic tire comprises: a metal layer 8 formed by printing processing on a surface of a side wall rubber 6 after cure. The metal layer 8 coats an area Ar which is not buried in the side wall rubber 6 and whose height from a lower end of a bead part 1 is 25% or more and 80% or less of tire maximum height H in a tire meridian cross section. The metal layer 8 is extended continuously along a tire circumferential direction and is an annular shape.

Description

  The present invention relates to a pneumatic tire, a run-flat tire, and a method for manufacturing the same, with optimized durability.

  It is known that pneumatic tires generate heat when rubber is repeatedly bent during traveling, and deterioration is accelerated due to heat storage, so that durability is reduced. In a general pneumatic tire, since the buttress part of the sidewall part to the vicinity of the bead part repeatedly bends and deforms, the durability of the part tends to decrease.

  As a kind of pneumatic tire, a run flat tire is known in which a hard reinforcing rubber having a crescent-shaped cross section is provided inside a sidewall portion so that a predetermined distance can be traveled even when the tire is punctured. In a run-flat tire, since the hard reinforcing rubber repeatedly deforms during run-flat travel (during puncture travel), durability tends to decrease due to heat storage.

  In order to reduce such heat storage, Patent Document 1 discloses that in a run-flat tire, the tire extends along the tire radial direction in contact with the reinforcing rubber and is folded around the bead core along the surface of the sidewall portion. It is disclosed that a heat conductive member (for example, a metal cord) extending radially outward in the inside is provided. This tire seems to improve heat dissipation through the heat conducting member.

  As another means for reducing the heat storage of the belt layer, in Patent Document 2, in a general pneumatic tire, the belt layer is laminated, and from both ends of the belt layer to the vicinity of the surface of the sidewall portion through the inside of the tire. Providing an extended thermal conductive layer is disclosed. This tire also seems to improve heat dissipation through the heat conductive layer.

JP 2008-273288 A JP 2009-234333 A

  However, in the configuration of Patent Document 1, it is very difficult and time-consuming to arrange and mold the heat conductive member from the liner to the surface of the sidewall portion, which is not practical. In addition, since a heterogeneous heat conductive member is embedded in the sidewall rubber, a failure such as a crack is caused due to a difference in rigidity and adhesiveness between materials, and durability is impaired.

  Moreover, since the structure of patent document 2 also embeds a heterogeneous heat conductive layer inside the rubber, the durability is impaired.

  The present invention has been made paying attention to such a problem, and its object is to improve heat dissipation and suppress the occurrence of cracks to improve durability and run flat tires. And a method of manufacturing these.

  In order to achieve the above object, the present invention takes the following measures.

  That is, the pneumatic tire of the present invention includes a metal layer formed by a printing process on the surface of a vulcanized sidewall rubber, and the metal layer is not embedded in the sidewall rubber, and is beaded in a tire meridian section. Covering at least a part of the region where the height from the lower end of the tire is 25% or more and 80% or less of the maximum tire height, and the metal layer extends along the tire circumferential direction and is continuous and annular It is characterized by.

  In this way, the metal layer is formed by printing on the surface of the vulcanized sidewall rubber and is not embedded in the sidewall rubber, so that cracks due to rigidity between materials do not occur. Moreover, the region where the height from the lower end of the bead portion is 25% or more and 80% or less of the maximum tire height is a portion in the sidewall rubber that repeatedly undergoes bending deformation and easily stores heat. Since the metal layer is formed in the part and has a continuous annular shape extending along the tire circumferential direction, heat can be transferred also in the circumferential direction, improving the heat dissipation effect and improving the durability. It becomes possible.

  Specifically, the printing process is preferably water transfer printing or vacuum deposition printing.

  In order to make it difficult for the metal layer to be peeled off, it is preferable that the surface of the sidewall rubber covered with the metal layer has a minute uneven portion.

  In order to improve the durability, it is preferable that an adhesive is interposed between the sidewall rubber and the metal layer.

  In a run flat tire having a hard reinforcing rubber having a crescent-shaped cross section inside the sidewall rubber, in order to enhance durability, the metal layer is formed with the hard reinforcing rubber when viewed along the tire axial direction. It is preferable to arrange in an overlapping position.

The method for producing a pneumatic tire according to the present invention includes a tire generating step for generating a tire by vulcanization and a printing step for forming a metal layer on the surface of the sidewall rubber of the vulcanized tire by a printing process. In the printing step, the metal layer is formed by a printing process so as to satisfy all of the following conditions (a) to (c).
(A) The metal layer is not embedded in the sidewall rubber (b) The metal layer is a region in which the height from the lower end of the bead portion is 25% or more and 80% or less of the maximum tire height in the tire meridian section. (C) The metal layer extends along the tire circumferential direction and is continuous and has an annular shape.

  Specifically, the printing process is preferably water transfer printing or vacuum deposition printing.

  In order to make it difficult for the metal layer to be peeled off, in the tire generation step, a minute uneven portion is formed on the surface of the sidewall rubber, and in the printing step, the metal layer is formed so as to cover the minute uneven portion. It is preferable.

  In order to improve durability, an adhesive is applied to the surface of the sidewall rubber after the tire generating step, and then the printing step is performed between the sidewall rubber and the metal layer. It is preferable to interpose the adhesive.

  In order to apply the present invention to a run flat tire, in the tire generating step, a run flat tire having a hard reinforcing rubber having a crescent-shaped cross section inside the sidewall rubber is generated. In the printing step, the tire axial direction When it sees along, it is preferable to arrange | position the said metal layer in the position which overlaps with the said hard reinforcement rubber.

1 is a tire meridian cross-sectional view showing an embodiment of a pneumatic tire according to the present invention. The side view which shows one Example of the pneumatic tire which concerns on this invention. The side view which shows another Example. 1 is a tire meridian cross-sectional view showing an embodiment of a run flat tire according to the present invention. The flowchart which shows the manufacturing method of the pneumatic tire which concerns on this invention.

  Hereinafter, a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a tire meridian cross-sectional view. 2A and 2B are side views showing sidewall portions of the tire.

  As shown in FIG. 1, the pneumatic radial tire includes a pair of bead portions 1, sidewall portions 2 that extend outward from the respective bead portions 1 in the tire radial direction RD, and tire radial direction RD outer sides of both sidewall portions 2. And a tread portion 3 connected to the end. The bead portion 1 is provided with an annular bead core 1a formed by covering a converging body such as a steel wire with rubber and a bead filler 1b made of hard rubber.

  The tire also includes a toroidal carcass layer 4 that extends from the tread portion 3 through the sidewall portion 2 to the bead portion 1. The carcass layer 4 is provided between the pair of bead portions 1 and is locked in a state where its end is wound up via the bead core 1a. The carcass ply is formed by covering a cord extending substantially perpendicular to the tire equator CL with a topping rubber. Inside the carcass layer 4 is disposed an inner liner rubber 5 for maintaining air pressure.

  On the outer side of the carcass layer 4 in the tread portion 3, a belt 3a for reinforcing the carcass layer 4 and a tread rubber 3b are provided in order from the inner side to the outer side. The belt 3a is composed of a plurality of belt plies. The tread rubber 3b forms a ground plane.

  Further, a sidewall rubber 6 is provided outside the carcass layer 4 in the sidewall portion 2. A rim strip rubber 7 is provided outside the carcass layer 4 in the bead portion 1 so as to come into contact with a rim (not shown) when the rim is mounted.

  The tire is manufactured by vulcanization. A metal layer 8 is formed on the surface of the vulcanized sidewall rubber 6 by a printing process. Since the metal layer 8 is thin, it is indicated by a dotted line in the sectional view. The metal layer 8 may be a metal having a thermal conductivity of 5 W / mK or more. For example, metals such as aluminum, silver, gold, duralumin, copper, chromium, beryllium, barium, iridium, magnesium, and tungsten can be used. As shown in FIG. 1, the metal layer 8 is not embedded in the sidewall rubber 6, and the height from the lower end of the bead portion 1 in the tire meridian section is 25% or more and 80% or less of the tire maximum height H. At least a part of the region Ar to be covered is covered. Since this region Ar is likely to store heat, it is better to cover it with the metal layer 8 as much as possible. However, a part of the surface may not be covered with the metal layer 8 in the case where a design or characters are formed on the tire surface. .

  In the example shown in FIGS. 1 and 2A, the metal layer 8 covers the entire region Ar. 2A, the metal layer 8 extends along the tire circumferential direction and is continuous and has an annular shape. In FIG. 2A, it has an annular shape.

  FIG. 2B shows a tire in which the metal layer 8 is coated on a part of the region Ar. As described above, the metal layer 8 makes one round along the tire circumferential direction and may have any shape as long as it has an annular shape. For example, the form in which the metal layer 8 is not formed in the part of the character and convex part which are formed on the tire surface is mentioned.

  In order to exhibit heat dissipation appropriately, the metal layer 8 should cover an area of at least 40% or more, preferably 80% or more of the total area of one round of the region Ar. In addition, since the metal layer 8 is formed by the printing process, the thickness is constant and uniform. In order to improve heat dissipation, the metal layer 8 may be formed in a region other than the region Ar. However, the metal layer 8 should not be provided in a region that contacts the rim flange. This is because the durability is impaired by contact with the rim flange.

  The metal layer 8 is formed by a printing process. As the printing process, a transfer method (for example, water transfer printing) or a vapor deposition method (for example, vacuum vapor deposition printing) can be used, and metal printing by an inkjet printer and a 3D printer is also possible.

  In order to make it difficult for the metal layer 8 to be peeled off and to increase the heat dissipation by increasing the surface area, minute uneven portions are formed on the surface of the sidewall rubber 6 covered with the metal layer 8 as shown in FIG. 3A. It is effective. Examples of the fine uneven portion include a Miura fold shape and a large uneven shape.

  In order to make the metal layer 8 difficult to peel off, it is preferable that an adhesive layer is interposed between the sidewall rubber 6 and the metal layer 8.

  FIG. 3 shows an example in which the present invention is applied to a run-flat tire. As shown in FIG. 3, the run-flat tire has a hard reinforcing rubber 9 having a crescent-shaped cross section inside the sidewall rubber 6. The hard reinforcing rubber 9 can travel even when air is released. Since heat is stored in the hard reinforcing rubber 9 during run flat running, the metal layer 8 is disposed at a position overlapping the hard reinforcing rubber 9 when viewed along the tire axial direction.

  As shown in FIG. 4, the tire manufacturing method includes a tire generation step (S100) for generating a tire by vulcanization, an adhesive application step (S101) for applying an adhesive to the surface of the sidewall rubber 6, and And a printing step (S102) of forming the metal layer 8 by a printing process so as to cover the sidewall rubber 6 (and adhesive). Note that the adhesive application step (S101) can be omitted as appropriate.

  In the tire generation step (S100), minute uneven portions are formed on the surface of the sidewall rubber 6. For example, you may form with the tire metal mold | die which has a fine uneven | corrugated | grooved part, and may form by cutting, after vulcanizing a tire.

In the printing step (S102), the metal layer 8 is formed by a printing process so as to satisfy all of the following conditions (a) to (c).
(A) The metal layer 8 is not embedded in the sidewall rubber 6 (b) The metal layer 8 has a height from the lower end of the bead portion 1 in the tire meridian section of 25% or more and 80% or less of the tire maximum height H. (C) The metal layer 8 extends along the tire circumferential direction and is continuous and has an annular shape.

  The pneumatic tire of this embodiment manufactured by this method includes a metal layer 8 formed by printing on the surface of the vulcanized sidewall rubber 6, and the metal layer 8 is not embedded in the sidewall rubber 6. In the tire meridian cross section, at least a part of the region Ar in which the height from the lower end of the bead portion 1 is 25% or more and 80% or less of the maximum tire height H is covered, and the metal layer 8 extends in the tire circumferential direction. It extends along and continues to form an annular shape.

  The metal layer 8 is formed by printing on the surface of the vulcanized sidewall rubber 6 and is not embedded in the sidewall rubber 6, so that cracks due to rigidity between materials do not occur. In addition, the region Ar in which the height from the lower end of the bead portion 1 is 25% or more and 80% or less of the tire maximum height H is a portion in the sidewall rubber 6 that repeats bending deformation and easily stores heat. Since the metal layer 8 is formed in the part and has a continuous annular shape extending along the tire circumferential direction, heat can be transferred also in the circumferential direction, and the heat radiation effect can be enhanced to improve durability. Is possible.

  In the present embodiment, the printing process is water transfer printing or vacuum deposition printing.

In the tire generation step (S100), when the minute irregularities are formed on the surface of the sidewall rubber 6, in the printing step (S102), the metal layer 8 is formed so as to cover the minute irregularities.
In the pneumatic tire according to this embodiment manufactured by this method, the surface of the sidewall rubber 6 covered with the metal layer 8 has minute uneven portions.
According to this configuration, since the metal layer 8 enters the minute concavo-convex portion, the metal layer 8 can be made difficult to peel off.

When an adhesive is applied to the surface of the sidewall rubber 6, the metal layer 8 is printed on the adhesive in the printing step (S102).
In the pneumatic tire of this embodiment manufactured by this method, an adhesive is interposed between the sidewall rubber 6 and the metal layer 8.
According to this configuration, the sidewall rubber 6 and the metal layer 8 can be appropriately bonded, and durability can be improved.

In the case of a run-flat tire, in the tire generation step (S100), a run-flat tire having a hard reinforcing rubber 9 having a crescent-shaped cross section inside the sidewall rubber 6 is generated. In the printing step (S102), the metal layer 8 is disposed at a position overlapping the hard reinforcing rubber 9 when viewed along the tire axial direction.
According to this method and configuration, the hard reinforcing rubber 9 that easily stores heat during the run-flat running and the metal layer 8 are positioned so as to overlap when viewed along the tire axial direction. It becomes possible to improve.

  In order to specifically show the configuration and effects of the present invention, the following evaluations were performed on the following examples.

(1) Durability In the evaluation, the test tire (245 / 40ZR18) was set at a constant air pressure of 80 kPa and a constant speed of 80 km / h. Drive 85% of JATMA specified maximum load for 4 hours, then load 90% of maximum load for 6 hours, then load 100% of maximum load and run 20% every 24 hours The vehicle continued to run while increasing the load until it failed. A tire on which nothing is printed is taken as a conventional example, and the conventional example is indexed as 100. The higher the value, the better the performance.

Example 1
The metal layer 8 was printed on the entire area Ar shown in FIG. The metal layer 8 is aluminum. The surface shape of the sidewall rubber 6 was the same as that of a normal tire.

Example 2
A minute uneven portion was formed on the surface of the sidewall rubber 6, and a metal layer 8 was formed thereon by printing. The rest is the same as the first embodiment.

Comparative Example 1
Instead of the metal layer 8, the same rubber as the sidewall rubber 6 was printed. Otherwise, it was the same as Example 1.

  In Table 1, it was found that the effects of the conventional example and the comparative example 1 were not obtained even when rubber was printed because there was no change in durability performance. Compared to the conventional example and the comparative example 1, each example has improved durability. This is considered to be due to the fact that the formation of the metal layer 8 increases the heat dissipation and improves the durability. Moreover, it is considered that the reason why 2 is superior to Example 1 is that the minute irregularities of the sidewall rubber 6 increase the surface area and improve the heat dissipation performance, and the metal layer 8 is difficult to peel off.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  The structure employed in each of the above embodiments can be employed in any other embodiment. The specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Bead part 6 ... Side wall rubber 8 ... Metal layer 9 ... Hard reinforcement rubber

Claims (10)

Provided with a metal layer formed by printing on the surface of the vulcanized sidewall rubber,
The metal layer is not embedded in the sidewall rubber and covers at least a part of a region where the height from the lower end of the bead portion is 25% or more and 80% or less of the maximum tire height in the tire meridian cross section. ,
The pneumatic tire is characterized in that the metal layer extends along the tire circumferential direction and is continuous and annular.   The pneumatic tire according to claim 1, wherein the printing process is water transfer printing or vacuum deposition printing.   The pneumatic tire according to claim 1 or 2, wherein a minute uneven portion is formed on a surface of the sidewall rubber covered with the metal layer.   The pneumatic tire according to claim 1, wherein an adhesive is interposed between the sidewall rubber and the metal layer. The tire according to any one of claims 1 to 4,
A hard reinforcing rubber having a crescent-shaped cross section inside the sidewall rubber;
The said metal layer is a run flat tire arrange | positioned in the position which overlaps with the said hard reinforcement rubber, when it sees along a tire axial direction. A tire generation step of generating a tire by vulcanization, and a printing step of forming a metal layer by a printing process on the surface of the sidewall rubber of the tire after vulcanization,
In the printing process, the metal layer is formed by a printing process so as to satisfy all of the following conditions (a) to (c).
(A) The metal layer is not embedded in the sidewall rubber (b) The metal layer is a region in which the height from the lower end of the bead portion is 25% or more and 80% or less of the maximum tire height in the tire meridian section. (C) The metal layer extends along the tire circumferential direction and is continuous and has an annular shape.   The method for manufacturing a pneumatic tire according to claim 6, wherein the printing process is water transfer printing or vacuum deposition printing. In the tire generation step, forming a micro uneven portion on the surface of the sidewall rubber,
The method for manufacturing a pneumatic tire according to claim 6 or 7, wherein in the printing step, the metal layer is formed so as to cover the minute uneven portions.   The adhesive is applied to the surface of the sidewall rubber after the tire generating step, and then the printing step is executed to interpose the adhesive between the sidewall rubber and the metal layer. The manufacturing method of the pneumatic tire in any one of -8. A method according to any one of claims 6-9,
In the tire generation step, a run flat tire having a hard reinforcing rubber having a crescent-shaped cross section inside the sidewall rubber is generated,
In the printing step, the metal layer is disposed at a position overlapping the hard reinforcing rubber when viewed along the tire axial direction.

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