JP4220201B2 - Safety tire - Google Patents

Description

【００１８】
（注）
*１ マイクロカプセル：膜材はメタクリル樹脂（融点は１４０℃）
*２ 熱可塑性樹脂：材質はメタクリル樹脂（融点は約１４０℃）
*３ 加硫促進剤：「ＴＯＴ」〔テトラキス（２−エチルヘキシル）チウラムジスルフィド、大内新興化学工業社製〕
*４ ｐｈｒ：ゴム成分１００質量部当たりの配合質量部数
上記の結果より、本発明におけるサイド補強ゴム層を用いたタイヤは、ランフラット耐久性を実用可能なレベルに保ちつつ、かつ乗り心地性を大幅に改善することができることが分かる。特に、高温加硫進行剤を、それに含まれる加硫促進剤相当量として０．５〜８ｐｈｒの範囲で配合した実施例１〜３において、その著しい効果が認められる。
【００１９】
【発明の効果】
本発明の安全タイヤによれば、サイド補強ゴム層に特定のゴム組成物を用いることにより、通常走行における乗り心地性を改善できると共に、ランフラット走行時には、発熱による高温化でサイド補強ゴム層の動的弾性率が増加して車体の支えとして作用するため、ランフラット耐久性の維持及び向上にも優れたタイヤが得られる。
【図面の簡単な説明】
【図１】本発明の安全タイヤの一例を示す左半断面図である。
【符号の説明】
１：ビード部
２：カーカス層
３：トレッド部
４：補強ベルト
５：サイドウォール部
６：インナーライナー層
７：サイド補強ゴム層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a safety tire using a specific rubber composition in a pair of annular (cross-sectionally crescent-shaped) rubber reinforcing layers (hereinafter sometimes referred to as side reinforcing rubber layers) disposed in a sidewall portion, In particular, the present invention relates to a safety tire that has both run-flat durability and ride comfort.
[0002]
[Prior art]
In the conventional safety tire, in order to improve the rigidity of the sidewall portion, a side reinforcing rubber layer made of a rubber composition alone or a composite of the rubber composition and fibers is disposed. However, when the tire's internal pressure (hereinafter referred to as internal pressure) decreases due to puncture, etc., so-called run-flat driving state, the deformation of the side reinforcing rubber layer increases as the deformation of the sidewall portion of the tire increases. However, the tire temperature may reach 200 ° C. or higher in some cases. However, in such a state, the side reinforcing rubber layer may exceed the fracture limit, possibly resulting in a tire failure.
As a means of gaining time to such a failure, such as increasing the maximum thickness of the side reinforcing rubber layer and the bead filler to be disposed, such as those that increase the volume of the rubber, or those that use a hard rubber (for example, However, when such a method is used, unfavorable situations such as deterioration in riding comfort, increase in weight, and increase in noise level may occur.
[0003]
On the other hand, if the volume of the side reinforcing rubber layer and the beat filler to be disposed is reduced in order to avoid the above-described situation, for example, deterioration in riding comfort, the load during run flat cannot be supported, and the side of the tire during run flat The deformation of the wall portion becomes very large, leading to an increase in heat generation of the rubber composition, and as a result, the tire has a problem of causing failure earlier.
Similarly, when the rubber used is made less elastic by changing the compounding material, the load during run flat cannot be supported, and the repeated deformation of the sidewall portion of the tire becomes very large. The actual situation is that an increase in the heat generated by the object is caused, and as a result, the tire will fail earlier.
[0004]
For this reason, tires having a side reinforcing layer having a soft elastic porous portion in a highly rigid rubber (see Patent Document 2), hard and soft as tires that achieve both run-flat durability and riding comfort in normal driving. A tire with a combination of two types of rubber, with soft rubber disposed on the portion most subjected to compression (see Patent Document 3), or a tire having a side reinforcing rubber layer in which rubbers of different hardness are disposed in a wave shape (Patent Documents 4 and 5) However, if there is such a soft part, durability will be a problem unless the side reinforcing rubber layer is thickened. It is the present situation that the difficulty of this is great.
[0005]
[Patent Document 1]
JP 11-263106 A (2nd page)
[Patent Document 2]
JP 2002-019431 A (first page)
[Patent Document 3]
JP-A-5-238215 (Page 2)
[Patent Document 4]
JP 2001-138721 A (first page)
[Patent Document 5]
JP 2000-343914 A (first page)
[0006]
[Problems to be solved by the invention]
Under such circumstances, the present invention devised the rubber composition used for the side reinforcing rubber layer to maintain the ride-flat durability, which is the function of the run-flat tire, while maintaining the ride comfort during normal driving. An object of the present invention is to provide a tire that improves the above-mentioned and has few manufacturing difficulties.
[0007]
[Means for Solving the Problems]
In the present invention, as a result of repeated studies to achieve the above object, the inventors have a relatively low elastic modulus when a composition in a specific semi-vulcanized state is used as the side reinforcing rubber layer. Riding comfort during normal running is not impaired, and during run flat running, the vulcanization reaction proceeds and hardens with heat generated by strain, and the tire (vehicle body) can be supported to improve durability during run flat running. I found. The present invention has been completed based on such findings.
[0008]
The present invention includes a pair of left and right bead portions, at least one carcass layer connected from one of the bead portions to the other, a tread portion disposed on the outer side in the tire radial direction of the carcass layer, and the tread portion. A pair of side wall portions disposed on the left and right sides, an inner liner layer positioned inside the carcass, and a pair of annular side reinforcing rubber layers positioned between the carcass and the inner liner layer corresponding to the side wall portions In the safety tire, the at least part of the side reinforcing rubber layer has a dynamic elastic modulus of 1 of the dynamic elastic modulus before the internal pressure is lowered when the internal pressure is reduced. The present invention provides a safety tire characterized in that it is composed of a rubber composition that is increased by a factor of 2 or more.
In the present invention, at least a part of the side reinforcing rubber layer is made of a low vulcanization rubber, and the low vulcanization rubber contains a vulcanizing agent and / or a vulcanization accelerator at a temperature of 130 to 160 ° C. The present invention provides a safety tire comprising a rubber composition blended with a high-temperature vulcanization accelerator to be released.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the safety tire of the present invention, the side reinforcing rubber layer is composed of a specific rubber composition that increases the dynamic elastic modulus at a heat generation temperature due to repeated strain corresponding to running in a state where the internal pressure is reduced. That is, the side reinforcing rubber layer in the present invention acts as a relatively low elastic modulus rubber excellent in ride comfort in normal tire traveling, and preferably at least a part thereof is a rubber in a semi-vulcanized state. Is.
Also, during run-flat running, the vulcanization reaction proceeds and cures with the heat generated by the repeated strain of the sidewall, and the elastic modulus of the side reinforcing rubber layer increases to support the tire (vehicle body), thereby running the run-flat. Durability at the time can be improved.
For this reason, at least a part of the side reinforcing rubber layer needs to be made of a rubber composition that increases its hardness or elastic modulus in running with a reduced internal pressure. It consists of a rubber member of a rubber composition that increases the modulus (E ′) to 1.2 times or more the dynamic elastic modulus (E ′) before the decrease in internal pressure.
The rubber member is a low vulcanized rubber and is made of a microcapsule enclosing a vulcanization accelerator and / or a vulcanizing compound of a vulcanizing agent, or a thermoplastic resin mixed with these vulcanizing compounds. It is preferable that it is the rubber composition which mix | blended the high temperature vulcanization | promotion promoter which becomes. By using such a rubber composition, it is possible to easily manufacture a tire having a side reinforcing rubber layer including a member in a desired semi-vulcanized state while easily adjusting the vulcanization speed.
[0010]
The high-temperature vulcanization accelerator is mixed with the rubber composition in a state where a predetermined vulcanization accelerator and / or vulcanizing agent is encapsulated or dispersed in a microcapsule or a thermoplastic resin in a normal running tire. Has been. Specifically, the high-temperature vulcanization accelerator may be a vulcanization accelerator and / or vulcanizing agent enclosed in the core of the microcapsule, and is mixed uniformly or non-uniformly in the thermoplastic resin. It may be dispersed in the state. Further, a combination of such microcapsules and a thermoplastic resin may be used.
As the material of the microcapsule film or the thermoplastic resin, the melting point is 130 to 130 in order to enable the release of the vulcanization accelerator and the vulcanizing agent when the temperature rises due to heat generation in the state where the internal pressure is lowered. The thing of 160 degreeC is used preferably. Examples of such a material include polyethylene, methacrylic resin, polyurethane, and polyacetal.
Further, the vulcanization accelerator encapsulated or mixed in the microcapsule or the thermoplastic resin is not particularly limited, but a thiuram compound is preferable, and in particular, a thiuram vulcanization having an alkyl group having 7 to 12 carbon atoms. Accelerators such as tetrakis (2-ethylhexyl) thiuram disulfide and the like can be mentioned.
By using such a high-temperature vulcanization promoter, the vulcanization degree of the rubber member at a predetermined position of the side reinforcing rubber layer can be easily suppressed in the production of a normal tire product, and in the run-flat running In the high temperature range, the resin of the material becomes liquid, and the vulcanization accelerator and / or vulcanizing agent can be released to proceed the vulcanization of the rubber member.
As a method for forming the microcapsules, a generally known method for forming microcapsules such as, for example, Japanese Patent Application Laid-Open No. 10-17706 can be employed.
[0011]
In the rubber composition used for the side reinforcing rubber layer of the tire of the present invention, the blending amount of the high-temperature vulcanization accelerator is such that the vulcanizing agent and the vulcanization accelerator contained therein are 100 parts by mass of the rubber component. It is preferable that the amount corresponds to 0.5 to 8 parts by mass. If it is less than 0.5, curing may not be sufficient, and if it exceeds 8 parts by mass, it may be cured too much and durability may be lowered.
In the rubber composition of the present invention, a diene rubber is preferably used as a rubber component. Examples of the diene rubber include ordinary natural rubber and diene synthetic rubber. Examples of the diene rubber include styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), and butyl rubber (IIR). ), Ethylene-propylene-diene copolymers and mixtures thereof.
[0012]
In the present invention, a certain degree of effect can be obtained even if the entire side reinforcing rubber layer is a semi-vulcanized rubber. However, if the adhesion to the carcass rubber or inner liner rubber which is a peripheral member is not sufficient, a failure may occur from the interface part during run flat running. The side reinforcement rubber layer has a multi-layer structure, and the part closer to the center is closer to the unvulcanized rubber (low vulcanized rubber), and the outer part has sufficient adhesion to the peripheral members. What was made is preferable. And it is preferable that the said high temperature vulcanization | cure promoter is mix | blended with this low vulcanization degree rubber | gum.
As described above, by making the central portion of the side reinforcing rubber layer close to the unvulcanized rubber, the microcapsules and / or the thermoplastic resin are unevenly distributed in the central portion of the side reinforcing rubber layer, thereby obtaining a run flat. Sometimes it can be advantageous to cause hardening or an increase in elastic modulus.
In addition, as described above, the melting point of the microcapsule membrane material or the thermoplastic resin is preferably 130 to 160 ° C., but the maximum reached temperatures in the rubber kneading step and the vulcanization step during tire production are the microcapsule membrane material and the thermoplastic resin. The temperature is preferably 10 ° C. or more lower than the respective melting points. This can prevent the vulcanization accelerator and / or vulcanizing agent from being unnecessarily released.
[0013]
Next, the present invention will be described with reference to the drawings. FIG. 1 shows an example of a safety tire according to the present invention, a pair of left and right bead portions 1, at least one carcass layer 2 connected from one of the bead portions to the other, and the outer side of the carcass layer in the tire radial direction. A tread portion 3 disposed on the tread portion, a reinforcing belt 4 disposed between the crown regions of the tread rubber layer and the carcass layer, a pair of sidewall portions 5 disposed on the left and right of the tread portion, and the inside of the carcass And a pair of annular side reinforcing rubber layers 7 having a substantially crescent-shaped cross section located between the carcass and the inner liner layer corresponding to the side wall portion. In addition, at least a part of the rubber member of the side reinforcing rubber layer 7 is made of a rubber composition that increases the hardness or the elastic modulus in running with the internal pressure lowered.
In particular, this rubber member is a rubber composition that increases its dynamic elastic modulus (E ′) to 1.2 times or more of the dynamic elastic modulus (E ′) before the decrease in internal pressure, or a low vulcanized rubber. And a rubber composition containing a high-temperature vulcanization accelerator that releases a vulcanizing agent and / or a vulcanization accelerator at a temperature of 130 to 160 ° C. is preferable.
[0014]
That is, if a semi-vulcanized rubber composition is used for at least a part of the side reinforcing rubber layer, it has a relatively low elastic modulus during normal running and does not impair riding comfort. Durability during run-flat running can be improved by supporting the tire by curing and curing the vulcanization reaction with heat generated by strain. In the rubber composition of the present invention, various chemicals usually used in the rubber industry, for example, vulcanizing agents, vulcanization accelerators, process oils, anti-aging, are used as long as the object of the present invention is not impaired. Agent, scorch inhibitor, zinc white, stearic acid, and the like.
In addition, as a gas with which the tire is filled, an inert gas such as normal or air having a changed oxygen partial pressure, or nitrogen can be used.
[0015]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various measurements were performed according to the following methods.
(1) Run flat durability Each prototype tire is assembled with a rim at normal pressure, and the internal pressure is sealed at 230 kPa and left at room temperature of 38 ° C. for 24 hours, then the valve core is removed and the internal pressure is set to atmospheric pressure. The drum running test was performed under the conditions of .17 kN (425 kg), speed 89 km / hr, and room temperature 38 ° C. The distance up to the occurrence of the failure at this time is the run flat durability, and the run flat durability is better as the value is expressed as an index with Comparative Example 1 being 100.
(2) Ride Comfort Trial tires were mounted on a passenger car, and a ride comfort feeling test was conducted by two specialized drivers, and a score of 1 to 10 was assigned to obtain an average value. The higher the value, the better the ride comfort.
[0016]
Examples 1 to 5 and Comparative Example 1
<Preparation of rubber composition>
For the rubber component consisting of 30 parts by mass of natural rubber and 70 parts by mass of butadiene rubber (cis-1,4-polybutadiene), the type and amount of high-temperature vulcanization accelerator shown in Table 1 is 50 masses of carbon black (FEF). Parts, process oil 5.0 parts by mass, zinc white 4.5 parts by mass, stearic acid 1.0 part by mass, anti-aging agent 6C (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylene A rubber composition comprising 2.0 parts by mass of diammine), 0.5 parts by mass of vulcanization accelerator NS (Nt-butyl-2-benzothiazolylsulfenamide), and 3 parts by mass of sulfur was prepared.
<Manufacture of tires>
A passenger car (tire size 215 / 45ZR17) with a different side reinforcing rubber layer was produced according to a conventional method. In Examples 1 to 5, the structure of the side reinforcing rubber layer is a crescent-shaped three layer, of which the layers on the carcass side and the inner liner side have a maximum thickness of 1.5 mm. A low vulcanization rubber made of the above rubber composition was used for the central rubber layer. The side reinforcing rubber layer of the tire of Comparative Example 1 was a conventional rubber made of a crescent-shaped layer. The maximum thickness of each side reinforcing rubber layer as a whole was 10 mm.
The tires thus obtained were evaluated for ride comfort and run flat durability. The results are shown in Table 1.
[0017]
[Table 1]

[0018]
(note)
* 1 Microcapsules: Membrane material is methacrylic resin (melting point is 140 ° C)
* 2 Thermoplastic resin: Methacrylic resin (melting point is about 140 ° C)
* 3 Vulcanization accelerator: “TOT” [tetrakis (2-ethylhexyl) thiuram disulfide, manufactured by Ouchi Shinsei Chemical Co., Ltd.]
* 4 phr: Number of parts by mass per 100 parts by mass of the rubber component From the above results, the tire using the side reinforcing rubber layer in the present invention maintains the run-flat durability at a practical level and has a comfortable ride. It can be seen that it can be greatly improved. In particular, in Examples 1 to 3 in which the high-temperature vulcanization accelerator is blended in the range of 0.5 to 8 phr as the equivalent amount of the vulcanization accelerator contained therein, the remarkable effect is recognized.
[0019]
【The invention's effect】
According to the safety tire of the present invention, by using a specific rubber composition for the side reinforcing rubber layer, it is possible to improve riding comfort in normal driving, and at the time of run flat driving, the temperature of the side reinforcing rubber layer is increased by heat generation. Since the dynamic elastic modulus increases and acts as a support for the vehicle body, a tire excellent in maintaining and improving run-flat durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a left half sectional view showing an example of a safety tire of the present invention.
[Explanation of symbols]
1: Bead part 2: Carcass layer 3: Tread part 4: Reinforcing belt 5: Side wall part 6: Inner liner layer 7: Side reinforcing rubber layer

Claims (9)

A pair of left and right bead portions, at least one carcass layer connected from one of the bead portions to the other, a tread portion disposed on the outer side in the tire radial direction of the carcass layer, and disposed on the left and right of the tread portion A pair of sidewall portions, an inner liner layer located inside the carcass, and a pair of annular side reinforcing rubber layers located between the carcass and the inner liner layer corresponding to the sidewall portions. In the safety tire, at least a part of the side reinforcing rubber layer has a dynamic elastic modulus that is 1.2 times or more of the dynamic elastic modulus before the internal pressure is lowered when the internal pressure is reduced. A safety tire characterized by comprising a rubber composition to be increased. The said member of a side reinforcement rubber layer consists of a rubber composition formed by mix | blending the high temperature vulcanization | cure progressing agent which advances a vulcanization reaction by the raise temperature by the heat_generation | fever during driving | running | working in the state where the internal pressure fell. Safety tire. The safety tire according to claim 1 or 2, wherein the high-temperature vulcanization accelerator releases a vulcanizing agent and / or a vulcanization accelerator at 130 to 160 ° C. A pair of left and right bead portions, at least one carcass layer connected from one of the bead portions to the other, a tread portion disposed on the outer side in the tire radial direction of the carcass layer, and disposed on the left and right of the tread portion A pair of sidewall portions, an inner liner layer located inside the carcass, and a pair of annular side reinforcing rubber layers located between the carcass and the inner liner layer corresponding to the sidewall portions. In the safety tire, at least a part of the side reinforcing rubber layer is made of a low vulcanized rubber, and the low vulcanized rubber is a vulcanizing agent and / or a vulcanization accelerator at a temperature of 130 to 160 ° C. A safety tire comprising a rubber composition containing a high-temperature vulcanization accelerator that releases an agent. The safety tire according to claim 2, 3 or 4, wherein the high-temperature vulcanization accelerator is a microcapsule encapsulating at least one vulcanizing compound selected from the group of vulcanizing agents and vulcanization accelerators. The safety according to claim 2, 3 or 4, wherein the high-temperature vulcanization accelerator is a thermoplastic resin obtained by mixing and dispersing at least one vulcanizing compounding agent selected from the group of vulcanizing agents and vulcanization accelerators. tire. The blending amount of the high-temperature vulcanization accelerator is an amount corresponding to 0.5 to 8 parts by mass per 100 parts by mass of the rubber component as a total amount of the vulcanizing agent and the vulcanization accelerator contained therein. The safety tire according to any one of the above. The safety tire according to any one of claims 1 to 7, wherein the side reinforcing rubber layer is formed of a plurality of layered member rubbers, and the rubber layer closer to the center is made of a low vulcanization degree rubber. Manufactured so that the maximum temperature reached in the rubber kneading step and the vulcanization step is 10 ° C. or more lower than the melting points of the microcapsule membrane material and the thermoplastic resin constituting the high-temperature vulcanization accelerator during tire production. The safety tire according to any one of claims 1 to 8.

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