JP2002144812A - Safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety tire capable of stable running even in its damaging condition, without sacrificing rolling resistance and comfortableness at ordinary running time of the tire before its damages. SOLUTION: In this safety tire, arranging a composite material composed of a continuous phase by a polymer and a closed cell in an inner side of the hollow doughnut-shaped tire, this composite material foams a foaming composition containing a foaming agent by a mean content of 10 to 45 mass%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety tire which is not affected by a puncture caused by an injury or the like, and more particularly to a safety tire which is excellent in both durability and riding comfort in running after being damaged.

[0002]

2. Description of the Related Art In a pneumatic tire, for example, in the case of a tire for a passenger car, air is sealed in the tire to reduce the internal pressure to two.
By maintaining the pressure at about 50 to 350 kPa, a tension is generated in a tire frame such as a carcass and a belt of the tire, and the deformation of the tire with respect to the input to the tire and the restoration thereof are enabled by the tension. That is, by maintaining the internal pressure of the tire in a predetermined range, a constant tension is generated in the skeleton of the tire to provide a load supporting function and increase rigidity, such as driving, braking and turning performance. It provides the basic performance required for running the vehicle.

[0003] When the tire held at the predetermined internal pressure is damaged, air leaks out to the outside through the wound and the tire internal pressure decreases to the atmospheric pressure, resulting in a so-called pan state. Most of the tension generated in the part is lost. Then, the load supporting function and the driving, braking, and turning performances obtained by applying a predetermined internal pressure to the tire are also lost, and as a result, the vehicle equipped with the tire cannot travel.

[0004] Therefore, many proposals have been made for safety tires that can run even in a punctured state. For example, as a pneumatic safety tire for automobiles,
Various types have been proposed, such as those having a double wall structure, those having a load supporting device disposed in a tire, and those having a reinforced tire side portion. Among these proposals, the technology actually used is a tire provided with a side reinforcing layer made of relatively hard rubber on the inner surface from the shoulder portion to the bead portion around the sidewall portion of the tire. This type of tire is mainly used as a run-flat tire having an aspect ratio of 60% or less.

However, a technique for adding a side reinforcing layer is as follows.
Since the longitudinal spring constant of the tire is increased by increasing the tire weight by 30 to 40%, there is a disadvantage that the rolling resistance is significantly deteriorated and the riding comfort during normal running before puncturing is reduced.
Therefore, it has a bad influence on the performance, fuel efficiency and environment during normal running, and is therefore a technology that is still poor in versatility.

On the other hand, in a pneumatic tire having a high tire section height and an aspect ratio of 60% or more, a rim such as a core is attached to a rim in order to avoid heat generation in a sidewall portion due to relatively high speed and long distance running. Run-flat tires having a structure in which an internal support is fixed to support a puncture load are mainly applied.

However, the tire cannot withstand local repeated input generated between the tire and the internal support during the so-called run flat running after the puncture, and as a result, the running distance after the puncture is 100 It was limited to about 200 km. In addition, the operation of assembling the tire to the rim after disposing the internal support inside the tire has been a problem in that it is complicated and takes a long time. In this regard, there has been proposed a device in which a difference is provided in the rim diameter between the one end side and the other end side in the width direction of the rim so that the internal support can be easily inserted, but a sufficient effect has not been obtained.

In order to extend the running distance after puncturing of a run flat tire having an internal support, it is effective to add a frame material to make the tire structure heavier.
The addition of the skeletal material deteriorates rolling resistance and ride comfort during normal use, so it is not practical to employ this method.

Further, a tire in which closed-cell foam is filled into an internal cavity of an assembly of a tire and a rim to be attached thereto is disclosed in, for example, JP-A-6-127207 and JP-A-6-127207.
183226, JP-A-7-186610 and JP-A-8-332805. The tires proposed for these are mainly agricultural tires,
It is limited to special or small tires such as rally tires, motorcycle tires and bicycle tires. Therefore, its application to tires for passenger cars, tires for trucks and buses and the like, in particular, tires that emphasize rolling resistance and ride comfort has been unknown. Since all foams have a low expansion ratio, they have a large weight in place of the composite having bubbles, and inevitable deterioration in vibration riding comfort and fuel efficiency, and the inside of the closed cells is at atmospheric pressure. Therefore, it was not functionally sufficient to replace the high pressure air of the conventional tire.

[0010] Further, Japanese Patent No. 2987076 discloses a puncture-free tire in which a foam filler is inserted into the inner peripheral portion. In addition to the disadvantage that the pressure of the foam is extremely close to the atmospheric pressure, the foamless tire has a disadvantage. Is urethane-based, so that the energy loss due to the intermolecular hydrogen bonding of the urethane group is large and the self-heating property is high. Therefore, when the urethane foam is filled in the tire, the foam is heated by repeated deformation during rolling of the tire, and the durability is greatly reduced. In addition, since a material that is difficult to form air bubbles independently is used, air bubbles are easily communicated and it is difficult to retain gas, and a desired tire internal pressure (load supporting ability or deflection suppressing ability, the same applies hereinafter). There are disadvantages that cannot be obtained.

Further, Japanese Patent Application Laid-Open No. 48-70002 discloses that the outer periphery of a multi-cellular body mainly composed of closed cells is integrally wrapped with a 0.5 to 3 mm thick outer coating film of rubber, synthetic resin or the like. A puncture-less tire has been proposed in which a large number of sealed inflated pressure bubbles are filled in a tire and the tire is maintained at a specified internal pressure. In this technology, the amount of the foaming agent in the closed-cell body forming and blending raw material to be expanded pressure bubbles is at least equal to or greater than the tire inner volume in order to make the pressure inside the cells of the foam higher than normal pressure. The compounding amount of the foaming agent that generates gas is set, thereby aiming at the same performance as at least a normal pneumatic tire.

In the above-mentioned technology, in order to prevent gas in the bubbles in the inflated pressure foam from being dissipated, the envelope is integrally sealed with an envelope. However, the material of the envelope is exemplified by an automobile. Material such as a tubing or a tubing formulation. In other words, the wrap is sealed with a soft elastic outer coating film mainly composed of butyl rubber having low nitrogen gas permeability used for a tire tube or the like, and many of these are filled in the tire. As a manufacturing method, an unvulcanized tire tube is used as a soft elastic outer covering film, and an unvulcanized closed cell forming compound material is used as an inflation pressure foam, and after arranging a large number of these inside the tire / rim assembly, Foamed by heating to obtain a foam-filled tire. The air under normal pressure inside the tire due to the expansion of the foam,
Natural air is exhausted through the small exhaust holes in the rim.

Here, the internal pressure of a passenger car tire is generally set to about 250 to 350 kPa as an absolute internal pressure at room temperature. In the state of (about 140 ° C.), the pressure is about 1.4 times the internal pressure, and it is estimated from the gas state equation. However, at such a pressure level, it is not possible to avoid the occurrence of blown air resulting from insufficient vulcanization pressure. In order to avoid this blown phenomenon, it is necessary to greatly increase the compounding amount of the foaming agent to increase the pressure generated by foaming and to increase the heating temperature. However, the method of increasing the amount of the foaming agent is such that the internal pressure at room temperature is 300
Since the pressure greatly exceeds kPa, the performance is not satisfied as a pneumatic tire. In addition, the method of increasing the heating temperature causes a problem in durability in long-term use because the tire is greatly damaged due to thermal aging and the durability of the tire is greatly deteriorated.

Further, as the soft elastic outer covering film, a compound composition mainly composed of butyl rubber having a small nitrogen gas permeability, such as a tire tube, is used. However, since butyl rubber has an extremely slow vulcanization reaction rate, In order to complete the reaction, a large heating time is required at a temperature of about 140 ° C. This means that the crosslinking density of the soft elastic outer coating film is insufficient, and it is needless to say that this is one factor (details will be described later) of the occurrence of peeling of the soft elastic outer coating film. Also,
Prolonging the heating time further increases the damage of the tire due to the above-mentioned heat aging, so that a decrease in durability cannot be avoided and it cannot be said that it is an advantageous measure.

[0015]

SUMMARY OF THE INVENTION Therefore, the present invention
It is an object of the present invention to propose a safety tire that enables stable running even after tire damage without sacrificing rolling resistance and riding comfort during normal running.

[0016]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and found that in order to constantly maintain the internal pressure of the tire properly, the inside of the tire should not be damaged even if it is injured. Found that it is effective to provide a structure that does not leak gas. That is, the gist configuration of the present invention is as follows.

(1) In a safety tire in which a composite comprising a continuous phase of a polymer and closed cells is arranged inside a hollow donut-shaped tire, the composite contains a foaming agent of 10 to 4 times.
A safety tire obtained by foaming a foamable composition containing an average content of 5 mass%.

(2) A safety tire according to the above (1), wherein the foamable composition comprises a foaming agent encapsulated in resin particles.

(3) In the above (1) or (2), the foaming agent encapsulated in the foamable composition comprises a thermally decomposable foaming agent, a liquefied ethane fluorinated product, and a liquefied carbon number of 3 to 8 Linear aliphatic hydrocarbons and fluorinated products thereof, liquefied branched aliphatic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof, and liquefied alicyclic hydrocarbons having 3 to 8 carbon atoms And at least one selected from fluorinated compounds thereof.

(4) In the above (3), the thermally decomposable blowing agent is
A safety tire comprising at least one selected from dinitrosopentamethylenetetramine, azodicarbonamide, paratoluenesulfonylhydrazine and derivatives thereof, and oxybisbenzenesulfonylhydrazine.

(5) The safety tire according to any one of the above (1) to (4), wherein the composite comprises a continuous phase of resin and closed cells.

(6) In any one of the above (1) to (5), nitrogen, air, carbon dioxide,
Fluoride of ethane, linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, branched aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, and fatty acid having 3 to 8 carbon atoms A safety tire comprising at least one gas selected from the group consisting of a cyclic hydrocarbon and a fluorinated product thereof.

(7) In any one of the above (1) to (6), the continuous phase of the composite is an acrylonitrile copolymer,
Any of acrylic copolymer, vinylidene chloride copolymer, acrylonitrile / styrene resin, polyethylene resin, polypropylene resin, polyester resin, polystyrene / polyethylene copolymer, polyvinyl alcohol resin, nylon resin, diene rubber and butyl rubber A safety tire comprising at least one kind.

(8) In any one of the above (1) to (7), the continuous phase of the composite comprises an acrylonitrile-based polymer, and the acrylonitrile-based polymer is an acrylonitrile polymer, an acrylonitrile / methacrylonitrile copolymer. A safety tire characterized in that it is at least one selected from acrylonitrile / methyl methacrylate copolymer and acrylonitrile / methacrylonitrile / methyl methacrylate terpolymer.

(9) In any one of the above (1) to (7), the continuous phase of the composite comprises an acrylic copolymer, and the acrylic copolymer comprises a methyl methacrylate resin, a methyl methacrylate / acrylonitrile copolymer. A safety tire characterized in that it is at least one selected from a polymer, a methyl methacrylate / methacrylonitrile copolymer and a methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer.

(10) In any one of the above (1) to (7), the continuous phase of the composite comprises a vinylidene chloride-based copolymer, and the vinylidene chloride-based copolymer is
Acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / methacrylonitrile copolymer, vinylidene chloride / acrylonitrile / methacrylonitrile copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate copolymer, vinylidene chloride / methacrylonitrile A safety tire characterized in that it is at least one selected from the group consisting of a methacrylate / methyl methacrylate copolymer and vinylidene chloride / acrylonitrile / methacrylonitrile / methyl methacrylate copolymer.

(11) In any one of the above (1) to (10), the internal pressure of the bubbles contained in the composite at 25 ° C. is not less than 150 kPa in absolute pressure, and the thermal expansion onset temperature of the composite is A safety tire having a temperature of 80 to 180 ° C.

(12) In any one of the above (1) to (11), the internal pressure of the bubbles contained in the composite at 25 ° C. is at least 200 kPa in absolute pressure, and the thermal expansion onset temperature of the composite is A safety tire having a temperature of 80 to 180 ° C.

(13) In any one of the above (1) to (12), the air bubble content of the composite is from 80.00% by volume to 98.%.
75% by volume of a safety tire.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A safety tire according to the present invention will be described below with reference to FIG. That is, the illustrated safety tire has a composite 2 composed of a continuous phase of a polymer and closed cells inside a tire 1.
Is arranged. Note that the structure of the tire 1 is not particularly limited as long as the tire 1 generally follows various kinds of automobile tires, for example, passenger car tires. For example, the illustrated tire is a general automotive tire, and a belt 5 and a tread 6 are arranged on a crown portion of a carcass 4 extending in a toroidal shape between a pair of bead cores 3 in a radially outward direction of the tire. . In the drawings, reference numeral 7 denotes an inner liner layer, and reference numeral 8 denotes a rim.

Here, the composite 2 is obtained by adding a blowing agent to
It is important that the foamable composition containing an average content of mass% is foamed. That is, by using a foaming composition containing an average content of a foaming agent for forming closed cells of the composite at 10 mass% or more, it is possible to reduce the absolute amount of the resin that becomes a continuous phase in the composite. As a result, the weight of the tire is reduced. The weight reduction of the tire contributes not only to the improvement of the fuel efficiency of the automobile, but also to the improvement of the riding comfort and the steering stability by reducing the unsprung weight.

On the other hand, if the average content of the foaming agent exceeds 45 mass%, it becomes difficult to obtain the desired composite of the present invention. In the foamable composition having an average content of more than 45 mass%, in the process of foaming by heating, the internal pressure of the foam due to foaming rises rapidly, so that the continuous phase cannot follow the stretching deformation. Therefore, some closed cells in the composite exceed the limit of the volume expansion and burst. Tires in which such a composite is arranged are not preferred because expected performance may not be obtained.

The foaming agent encapsulated in the foamable composition to be a composite includes a thermally decomposable foaming agent, a liquefied ethane fluorinated product, and a liquefied linear C 3 to C 8. From aliphatic hydrocarbons and their fluorinated products, liquefied branched aliphatic hydrocarbons having 3 to 8 carbon atoms and their fluorinated products, and liquefied alicyclic hydrocarbons having 3 to 8 carbon atoms and their fluorinated products Preferably, at least one selected from them is used.

By encapsulating this foaming agent, nitrogen, air, fluorinated ethane, linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product and carbon number are contained in the closed cells of the composite. At least one selected from the group consisting of 3 to 8 branched aliphatic hydrocarbons and fluorinated products thereof, and 3 to 8 carbon atoms of alicyclic hydrocarbons and fluorinated products thereof is produced.

In particular, it is preferable to have an organic gas having 3 carbon atoms in the bubbles of the composite. Because the carbon number 3
This is because the organic gas has a relatively high vapor pressure and can maintain the tire internal pressure even at a low temperature.

Next, many of the pyrolytic foaming agents have a characteristic of generating nitrogen by thermal decomposition, and a composite obtained by appropriately controlling the reaction is a composite having nitrogen in its bubbles. Becomes As the thermally decomposable blowing agent, at least one selected from dinitrosopentamethylenetetramine (DPT), azodicarbonamide (ADCA), paratoluenesulfonylhydrazine (TSH) and its derivatives, and oxybisbenzenesulfonylhydrazine (OBSH) Is appropriate. A desired composite can be obtained by encapsulating these thermally decomposable foaming agents in a resin constituting a molten continuous phase.

On the other hand, when the foamable composition in the form of particles is filled in a tire and foamed, a composite is formed in a form in which existing air between particles and a carrier gas used for filling are partially taken in. Then, air and carrier gas remain in the bubbles. When filling the particulate foamable composition into the tire, air, nitrogen, fluoro gas, or the like is used as a filling carrier gas. preferable.

Here, in order to provide a predetermined tire pressure with the composite 2, the gas sealed at a predetermined pressure in the closed cells in the composite 2 does not leak from the bubbles to the outside of the composite.
In other words, it is also important that the continuous phase of the composite 2 has a property that gas is difficult to permeate. That is, the continuous phase of the composite 2 is made of a material having low gas permeability, specifically, polyvinyl alcohol resin, nylon resin, acrylonitrile polymer, acrylic polymer, vinylidene chloride polymer, acrylonitrile / It is essential that the material be at least one selected from the group consisting of styrene resin, polyethylene resin, polypropylene resin, polyester resin, polystyrene / polyethylene copolymer, and butyl rubber. Any of these materials can be relatively easily formed into a composite in a tire and has flexibility against input due to tire deformation.

In particular, it is preferable to apply any one of an acrylonitrile polymer, an acrylic polymer, a vinylidene chloride polymer, a nylon resin and a polyvinyl alcohol resin to the continuous phase of the composite. Further, acrylonitrile-based polymers include acrylonitrile /
Methacrylonitrile copolymer, acrylonitrile / methyl methacrylate copolymer and acrylonitrile /
At least one selected from a methacrylonitrile / methyl methacrylate terpolymer, and the acrylic polymer includes methyl methacrylate resin, methyl methacrylate / acrylonitrile copolymer and methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer. At least one selected vinylidene chloride-based polymer includes vinylidene chloride / acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / methacrylonitrile copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate copolymer. Merging, vinylidene chloride / acrylonitrile / methacrylonitrile copolymer, vinylidene chloride / methacrylonitrile / methyl methacrylate copolymer,
And at least one selected from vinylidene chloride / methyl methacrylate / acrylonitrile / methacrylonitrile copolymer, and a nylon resin,
Nylon 6, Nylon 11, Nylon 12, Nylon 6
At least one selected from the group consisting of a / 66 copolymer and a nylon 6/12 copolymer is advantageously suitable. Each of these materials has a small gas permeability coefficient and low gas permeability, so that the gas in the closed cells does not leak to the outside, and the internal pressure of the closed cells can be maintained in a predetermined range.

Further, when polymerizing the resin constituting the continuous phase, fluorinated ethane and C3 to C8
Linear aliphatic hydrocarbons and fluorinated products thereof, branched aliphatic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof, and alicyclic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof, and the like. Specifically, there is also a method of liquefying propane, butane, pentane, hexane, heptane, octane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and the like, and performing emulsion polymerization while dispersing in a reaction solvent, Thereby, expandable resin particles in which gas components such as propane, butane, pentane, hexane, heptane, octane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane are sealed in a liquid state in the continuous phase are obtained. It is possible,
When this is filled into the tire and formed into a composite by heating, propane, butane, pentane, hexaneheptane, octane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane are enclosed in the bubbles. . In addition, butane and pentane isomers include isobutane, isopentane,
Neopentane, 2-methylpentane, 2,2-dimethylbutane, methylhexanes, dimethylpentanes, trimethylbutane, methylheptane, dimethylhexanes, trimethylpentane, and the like can be given.

Further, the expandable resin particles containing a liquefied gas such as propane, butane, and pentane are charged into a tire together with a melt of a continuous phase forming a composite, and heated to form a composite inside. You can also get tires with your body placed.

The desired tire can be obtained by subjecting the foamable resin particles, which have been subjected to a surface coating such as a surfactant and an oil agent, to heating and foaming in a tire. Further, the target tire can also be obtained by preliminarily heating and foaming the resin particles containing the liquefied gas to form substantially spherical hollow particles, and filling the hollow particles into the tire.

Next, the continuous phase of the composite at 30 ° C.
Gas permeability coefficient is 300 × 10^-12 (Cc · cm / cm^Two 
S · cmHg) or less, preferably at 30 ° C.
Permeability coefficient is 20 × 10^-12 (Cc · cm / cm^Two ・ S ・
cmHg) or less, more preferably gas at 30 ° C.
Permeability coefficient is 2 × 10^-12 (Cc · cm / cm^Two ・ S ・ c
mHg) or less is recommended. This is usually
Gas Permeability of Inner Liner Layer in Pneumatic Tires
Excess coefficient is 300 × 10^-12 (Cc · cm / cm ^Two ・ S ・
cmHg) or less and sufficient internal pressure holding function
In view of its experience, the continuous phase of the composite
The gas permeability coefficient at 0 ° C. is 300 × 10^-12 (Cc ・
cm / cm^Two S · cmHg) or less.
However, at this level of gas permeability coefficient,
Since the internal pressure needs to be replenished about once, the maintenance
20 × 10^-12 (Cc · cm / cm^Two 
S · cmHg) or less, more preferably 2 × 10^-12 
(Cc · cm / cm^Two ・ S ・ cmHg) or less
Is recommended.

The gas is refilled into the bubbles by using a normal device for filling the tire with air, or by placing the tire in a closed room filled with a desired gas and maintaining a predetermined internal pressure, thereby reducing the internal pressure of the bubble. Can be adjusted again, but when a polymer having a large gas permeability coefficient is used for the continuous phase, this refilling operation must be performed frequently, which is not practical.

The composite 2 has closed cells in which individual cells are isolated by being surrounded by partition walls.
The internal pressure of the closed cells in the composite 2 at 25 ° C.
It is important that the pressure be 0 kPa or more, preferably 200 kPa or more. The internal pressure of the closed cell at 25 ° C is 150
If the pressure is less than kPa, the flexure of the composite becomes large and the amount of repeated deformation during rolling of the tire becomes large. Therefore, in addition to the increase in the fatigue history of the composite during normal running before the tire is injured, the composite caused by tire injuries The rate of damage development increases with an increase in the amount of deformation, and in this case also, the durability of the composite against repeated deformation is significantly reduced, and the performance when the tire is damaged and running is insufficient. Here, the internal pressure value is expressed as normal pressure (atmospheric pressure) of 100 kPa.
That is, the internal pressure of 200 kPa indicates that the pressure is twice the atmospheric pressure.

Further, the foamable composition for forming the composite 2 is as follows:
It is important to use one having an expansion start temperature of 80 to 180 ° C. Here, the expansion start temperature, when the foamable composition is heated under a constant heating condition, and reaches a certain temperature,
The polymer and the foaming agent constituting the continuous phase of the foamable composition are activated, and the vaporization or thermal decomposition of the foaming agent trapped in the polymer is promoted, and the surrounding polymer is softened. Better vaporization or thermal decomposition results in foaming and swelling. As a result, the volume of the foamable composition significantly increased. Therefore, the amount of displacement corresponding to the change in volume was measured, and the temperature at the time when the amount of displacement rose was defined as the expansion start temperature.

The internal temperature of the tire under the conditions of use in the general market is about 50 to 60 ° C. However, when the composite is disposed inside the tire, the internal temperature of the tire further increases due to the heat storage characteristics of the composite. It is easy to guess. That is, if the expansion start temperature of the foamable composition to be a composite is set too low, there is a possibility that the internal temperature of the tire exceeds the expansion start temperature. If the internal temperature of the tire exceeds the expansion start temperature, the flow of the continuous phase constituting the composite and the thermal expansion of the bubbles will disturb the bubble structure, connect the bubbles, and significantly increase the gas permeability of the continuous phase. It will be. If the tire is damaged in such a state, the vehicle cannot be driven because the load supporting function cannot be achieved as intended. Therefore, in order to ensure that the function of the safety tire in which the composite is arranged inside the tire, which is expected in the present invention, the inflation starts at a temperature range of 80 ° C. or higher, which is sufficient to avoid the above-mentioned problems. It is important to select a foamable composition that has a temperature.

Further, the bubble content in the composite 2 is 8
It is preferably from 0.00% to 98.75% by volume. Because, when the bubble content is less than 80.00% by volume, when the composite is deformed inside the tire, stress sporadically concentrates in a continuous phase portion between the bubbles, and cracks are easily generated in the continuous phase, and repeated. The durability of the composite to deformation is significantly reduced. Further, when the bubble content exceeds 98.75% by volume, the degree of damage to the composite due to tire trauma increases, and the speed of its development also increases,
Also in this case, the durability of the composite against repeated deformation is significantly reduced.

Here, the bubble content is a percentage of the volume of the bubble with respect to the volume of the composite disposed in the tire, and can be specifically calculated by the following equation. . Bubble content = {1− (use volume of resin or composition constituting composite / internal volume of tire)} × 100 where “use volume of resin or composition constituting composite” in the above formula Is
It refers to the volume of the composition before the closed cells are formed by foaming by heating or the like, and is a volume value not including the closed cell volume.

The used volume of the resin or the composition constituting the composite is determined, for example, by previously weighing the composition into a container having a known volume under atmospheric pressure.
In particular, when the resin or composition constituting the composite is in the form of particles, the composition is weighed in a measuring cylinder under atmospheric pressure, and the measuring cylinder is immersed in an ultrasonic water bath to give vibration, The volume value in a state where the packing between the material particles was stable was adopted. Therefore, when the resin or the composition is in the form of particles, the used volume means the sum of the total volume of the particles and the total volume of the voids between the composition particles.

The following methods can be used to maximize the durability of the composite used in the present invention. That is, during normal running (before the tire is damaged), the space between the composite and the inner surface of the tire is filled with air of about 200 to 400 kPa to actively compress the composite within the tire. With this contrivance, it is possible to reduce the load share ratio of the composite during normal running, and it is possible to reduce the fatigue history associated with repeated deformation during rolling of the tire. Therefore,
Even if the filling air between the composite and the tire inner surface is dissipated due to tire damage, compared to the case where the above method is not adopted,
The running performance under the condition of tire damage is greatly improved.

The tire having the composite 2 disposed inside is characterized in that even if the tire is damaged, the tension of a case such as a normal pneumatic tire is not easily reduced. Because, when the tire is injured, a part of the complex 2 is damaged on the inner surface of the tire near the injured,
The gas in some closed cells of this damaged part may escape to the outside of the tire. However, when this phenomenon is compared to a conventional pneumatic tire, the internal pressure is reduced only in a very small part of the region, so that the tire does not lose its case tension due to partial damage of the composite 2. Also, the conventional pneumatic tire does not fall into a flat state.
Further, the probability of damage to the composite 2 due to tire trauma is extremely low, and even if it is damaged, the area thereof is extremely limited, so that the tire internal pressure given by the composite 2
It cannot be so low as to impair tire function.

In addition, although the vicinity of the damaged closed cell drops to the atmospheric pressure, the closed cells in the surrounding area are, for example, 15 atmospheres.
As a result of instantaneous expansion due to having an internal pressure of 0 kPa or more, the area of the damaged closed cell is contracted and the damaged portion is instantly closed, and so-called self-healing becomes possible.

In arranging the composite inside the tire according to the present invention, by adding a liquid that does not substantially swell the continuous layer of the composite inside the tire, a tire damaged portion when the tire is damaged is added. It is possible to enhance the sealing function of the tire and further extend the running distance after the tire is damaged. That is, since the composite has a substantially spherical shape, it has high fluidity, and therefore can be easily filled into the tire and the rim assembly through an inlet having a small inner diameter such as a valve of the tire. On the other hand, when the tire is injured, the composite will collect on the inner surface of the injured part in an attempt to blow out from the injured part to the outside of the tire. However, since the damaged path from the inner surface of the damaged portion to the outer peripheral surface of the tire has a complicated and intricate shape instead of a straight line, the complex that has entered through the wound on the inner surface of the tire is impeded from moving along the path,
A large number of composites will gather in a compressed state on the inner surface of the damaged part, and the damaged part will be sealed by the composite. At that time, if the liquid is added together with the complex inside the tire, based on the affinity of the complex surface and the liquid and the viscosity of the liquid,
Since several to several thousand composites can be assembled, the damaged portion can be instantaneously filled with the aggregate of composites when the tire is damaged.

Further, since the liquid to be mixed has an apparently higher specific gravity than the composite, a large amount of the liquid is distributed on the inner surface of the tire tread due to the centrifugal force accompanying the rolling of the tire during normal running. This indicates that there are a large number of relatively large aggregates near the inner surface of the tire tread portion during normal running. Therefore, when the tire is injured by stepping on a foreign substance or the like, many of the composites that are aggregated through a relatively large amount of liquid quickly seal the damaged part, which is extremely effective.

In order to obtain a composite-filled tire mixed with a liquid, the following points must be taken into consideration in production. That is, when filling the tire, it is important to fill the complex in a state of high fluidity, in other words, in a dry state before being mixed with the liquid. The composite forms an aggregate by mixing with the liquid, as described above. Therefore, the composite mixed with the liquid has extremely low fluidity, which makes it difficult to fill the tire. Therefore, a method of applying the liquid to be mixed to the inner surface of the tire or the rim before filling, or a method of injecting the liquid into the tire and the rim assembly after filling the complex is efficient and reliable.

Examples of the liquid used here include silicone oil and aliphatic polyhydric alcohols represented by ethylene glycol and propylene glycol.

The safety tire according to the present invention is characterized in that the pressure inside the closed cell of the composite disposed particularly is higher than the atmospheric pressure. The following new manufacturing methods largely depend. Although the production method will be specifically described below, it is preferable to monitor the internal pressure and the internal temperature of the tire during the production process and control the generation and growth of bubbles while appropriately adjusting the production method.

In the first method, after the foamable composition constituting the composite is placed inside the tire, the tire is incorporated into a rim, and then the tire assembly is heated to foam inside the tire. In addition, heating can be performed using microwaves or electron beams in addition to an oven or steam, and the same applies to the following method.

The second technique is to use a foaming composition, such as Expancel (trademark), which is a resin particle in which gas bubbles such as butane, propane, or pentane are liquefied and sealed, and then to a tire assembly after the rim assembly. Pour into the interior of the volume, then heat the tire assembly and foam inside the tire.

In particular, when the composite gas has a component composition containing an aliphatic fluorocarbon containing no chlorine, the above-described methods can be used, but the following methods are suitable. That is, the third technique is based on tetrafluoroethane, difluoroethane, fluoroethane, octafluoropropane, 2H-heptafluoropropane,
A foaming composition, which is a resin particle obtained by liquefying and encapsulating gas bubbles such as decafluorobutane, cyclofluorobutane and dodecafluoropentane, is injected into the tire assembly after the rim assembly, and then the tire assembly is heated, Foaming is performed inside the tire. In this case, the continuous phase of the composite becomes a polymer constituting the resin particles.

A fourth technique is to pre-heat and foam a foamable composition, which is a resin particle in which bubble gas such as butane, propane or pentane is liquefied and sealed, such as Expancel (trade name). The spherical hollow particles are filled into the tire and rim assembly. In this case, the continuous phase of the composite refers to a polymer constituting the shell of the resin particles. In particular, the above methods can also be used when the component gas contains an aliphatic fluorocarbon containing no chlorine as the bubble gas of the composite.

The continuous phase may be a combination of at least one polymer selected from acrylonitrile polymers, polyvinyl alcohol resins, acrylic polymers, vinylidene chloride polymers, nylon resins and butyl rubber. Further, at least one selected from dinitrosopentamethylenetetramine (DPT), azodicarbonamide (ADCA), paratoluenesulfonylhydrazine (TSH) and its derivatives, and oxybisbenzenesulfonylhydrazine (OBSH) as a foaming agent. The purpose can be achieved by using them together.

On the other hand, a tire usually has an inner liner layer on the inner peripheral surface thereof. The inner liner layer is formed of a nylon resin having a softening point of 170 to 230 ° C. and an isobutylene paramethylstyrene copolymer. It is preferable that the thermoplastic elastomer composition comprises a thermoplastic elastomer composition obtained by dynamically vulcanizing an elastomer component containing a halide to a gelation ratio of 50 to 95%. This is because, unlike the conventional inner liner layer mainly composed of butyl rubber, by using a nylon resin as the continuous phase, the gas permeation resistance becomes extremely good, so that the function of the inner liner layer can be enhanced. On the other hand, an elastomer component containing a halide of an isobutylene paramethylstyrene copolymer has a gelation ratio of 50 to 50%.
By making the thermoplastic elastomer composition dynamically vulcanized to 95%, an inner liner layer which is rich in flexibility and excellent in heat resistance and durability can be obtained. Then, by providing the inner liner layer with the above characteristics, it is possible to create an environment that makes it easier for the gas in the closed cells of the composite to remain in the cells.

The gelation ratio was determined by soxhlet extraction of the pelletized composition after biaxial kneading with acetone in a water bath for 8 hours, and the residue was further n-h-extracted for 8 hours.
By Soxhlet extraction with hexane, the unvulcanized elastomer component was extracted with a solvent, and the acetone and n-hexane extracts were dried and the weight of the solvent was measured. Gelation rate (%) = [{weight of all formulations-(extracted amount of acetone + extracted amount of n-hexane-amount of stearic acid)] / weight of all formulations] x 100

[0066] Further, the inner liner layer, the gas permeability coefficient at 30 ° C. is ^{20 × 10 -1 2 (cc ·} cm / c
m ² · s · cmHg) or less. This is because even if the gas permeability of the matrix (continuous phase) forming the composite is high, if the gas permeability of the inner liner layer is good, the gas bubbles in the composite are prevented from leaking out of the tire. This is advantageous in maintaining the internal pressure of the tire. That is, the superiority of the gas permeability of the inner liner layer is a factor that directly determines the pressure retention of the tire as a pressure vessel. Of course, it is fundamental that the gas permeability of the continuous phase forming the composite is low, and it is ideal to use an inner liner layer having a low gas permeability.

By arranging such a composite 2 and applying a predetermined internal pressure to the tire, an essential internal pressure is applied to the tire. That is, instead of filling the inside of the tire with air, the complex 2 is arranged inside the tire,
By applying a predetermined internal pressure to the tire, a structure capable of generating tension in the tire frame such as a carcass and a belt of the tire is realized. Accordingly, since the proper internal pressure is applied to the tire by the composite 2, there is no need to regulate the tire structure itself, and a new safety tire can be provided by utilizing a general-purpose tire and a general-purpose rim.

Although FIG. 1 shows the application of the foam to a general-purpose tire, it is also possible to apply the foam to a tire having a structure suitable for run flat as shown in FIG. 2, for example. . That is, the tire shown in FIG. 2 is provided with a side reinforcing layer 9 made of hard rubber particularly inside the sidewall portion of the tire to reinforce the side portion.

[0069]

EXAMPLE A tire having the structure shown in FIG.
Applying the complex of various specifications shown in the table as shown in the table,
Tire size 185 / 70R14, rim size 5.5J
A × 14 riding safety tire-rim assembly was prototyped.
Here, the tire 1 conforms to the general structure of the type and size of the tire. The types of the foamable compositions in Tables 1 and 2 are as shown in Table 3.

Here, the expansion start temperature in Table 3 was obtained by measuring the amount of expansion displacement under the following conditions, and setting the temperature at the time of the rise of the amount of expansion. Equipment: Nishizawa PERKIN-ELMER 7Series
(ThermalAnalysis System) Measurement conditions: heating rate 10 ° C./min, measurement start temperature 25
° C, measurement end temperature 200 ° C, physical quantity measured: The amount of expansion displacement caused by heating is measured.

Next, the pressures in the bubbles shown in Tables 1 and 2 were calculated by the following equation (A) based on the following definitions. Bubble pressure (kPa) = [(Wt / ρs) / Vt] 101.325 (A) where, Wt: weight of composite filled in tire Vt: internal volume of tire used for filling ρs : Specific gravity of the composite sampled from the tire under the atmospheric pressure, represented by ρs = Ws / Vs, where Vs: Volume of the composite sampled from the tire under the atmospheric pressure Ws: Sampling from the tire Weight of composite

The prototype tire thus obtained was subjected to 2000c
Installed on the front axle of a c-class passenger car,
The vehicle was run at 0 km / h, and the vibration level was evaluated. The evaluation was performed on a scale of 1 to 10, and the comparison was made based on the average of the scores of the two drivers. The larger the value, the better.

Next, each prototype tire was subjected to a drum running test at 5000 km and a load load of 4.18 kN to give a running history, and then mounted on a 2000 cc class passenger car. Then, the tire had a diameter of 3 mm and a length of 3 mm. Injuries were caused by penetrating the tread from the outside of the tire tread with a 3 cm nail, and then a load equivalent to 4 passengers was applied, and the test course was run at 90 km / h, and the possible travel distance was measured. did. Then, the values are indicated by an index when the travelable distance of the corresponding comparative example is set to 100.
The larger the value, the better the result.

The rolling resistance of the tire after running the drum was measured. The rolling resistance was measured by the coasting method. The load was tested under the conditions of JIS 100% load and the coasting start speed 100 km / h, and the work corresponding to the rolling resistance of the tire was determined from the speed drop curve of the coasting drum. The amount was determined and expressed as an index when the result of the corresponding comparative example was set to 100. The smaller this index is, the smaller the rolling resistance is. Based on these findings,
These are also shown in Tables 1 and 2.

[0075]

[Table 1]

[0076]

[Table 2]

[0077]

[Table 3]

Although the above-described embodiment has been applied to the tire having the structure shown in FIG. 1, the same effect by applying the present invention can be applied to the tire having the side reinforcing layer shown in FIG. Obtained.

[0079]

According to the present invention, it is possible to achieve a stable running even in a tire-damaged state without sacrificing rolling resistance and riding comfort during normal running before the tire is damaged. Tires can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view in the tire width direction showing a safety tire according to the present invention.

FIG. 2 is a sectional view in the tire width direction showing another safety tire according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 tire 2 composite 3 bead core 4 carcass 5 belt 6 tread 7 inner liner layer 8 rim 9 side reinforcement layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 101: 00 C08L 101: 00

Claims (13)

[Claims] 1. A safety tire in which a composite comprising a continuous phase of a polymer and closed cells is disposed inside a hollow donut-shaped tire, the composite comprises a foaming agent of 10 to 45%.
A safety tire obtained by foaming a foamable composition containing an average content of mass%. 2. The safety tire according to claim 1, wherein the foamable composition has a foaming agent encapsulated in resin particles. 3. The foaming agent according to claim 1, wherein the foaming agent encapsulated in the foamable composition is a pyrolytic foaming agent, a liquefied ethane fluorinated product, or a liquefied linear C 3-8. Hydrocarbons and fluorinated products thereof, liquefied branched aliphatic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof, and liquefied alicyclic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof A safety tire characterized in that it is at least one member selected from the group consisting of: 4. The method according to claim 3, wherein the thermally decomposable blowing agent is
A safety tire comprising at least one selected from dinitrosopentamethylenetetramine, azodicarbonamide, paratoluenesulfonylhydrazine and derivatives thereof, and oxybisbenzenesulfonylhydrazine. 5. The method according to claim 1, wherein
A safety tire, wherein the composite comprises a continuous phase of resin and closed cells. 6. The method according to claim 1, wherein
In the closed cell of the composite, nitrogen, air, carbon dioxide, fluorinated ethane, linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, branched aliphatic having 3 to 8 carbon atoms A safety tire comprising at least one gas selected from the group consisting of hydrocarbons and fluorinated products thereof, and alicyclic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof. 7. The method according to claim 1, wherein
The continuous phase of the composite is an acrylonitrile-based copolymer, an acrylic copolymer, a vinylidene chloride-based copolymer, an acrylonitrile / styrene resin, a polyethylene resin, a polypropylene resin, a polyester resin, a polystyrene / polyethylene copolymer, and a polyvinyl alcohol resin. A safety tire comprising at least one of nylon, nylon resin, diene rubber and butyl rubber. 8. The method according to claim 1, wherein
The continuous phase of the composite comprises an acrylonitrile-based polymer,
The acrylonitrile-based polymer is at least one selected from an acrylonitrile polymer, an acrylonitrile / methacrylonitrile copolymer, an acrylonitrile / methyl methacrylate copolymer, and an acrylonitrile / methacrylonitrile / methyl methacrylate terpolymer. Features safety tires. 9. The method according to claim 1, wherein
The continuous phase of the composite comprises an acrylic copolymer, which is a methyl methacrylate resin, a methyl methacrylate / acrylonitrile copolymer, a methyl methacrylate / methacrylonitrile copolymer, and a methyl methacrylate / acrylonitrile / methacrylonitrile. A safety tire characterized in that it is at least one selected from terpolymers. 10. The composite according to claim 1, wherein the continuous phase of the composite comprises a vinylidene chloride-based copolymer, wherein the vinylidene chloride-based copolymer comprises
Acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / methacrylonitrile copolymer, vinylidene chloride / acrylonitrile / methacrylonitrile copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate copolymer, vinylidene chloride / methacrylonitrile A safety tire characterized in that it is at least one selected from the group consisting of a methacrylate / methyl methacrylate copolymer and vinylidene chloride / acrylonitrile / methacrylonitrile / methyl methacrylate copolymer. 11. The composite according to claim 1, wherein the internal pressure of the bubbles contained in the composite at 25 ° C. is 150 kPa or more in absolute pressure, and the thermal expansion start temperature of the composite is 80 to 180 ° C. A safety tire, characterized in that: 12. The composite according to claim 1, wherein the internal pressure of the bubbles contained in the composite at 25 ° C. is at least 200 kPa in absolute pressure, and the thermal expansion start temperature of the composite is 80 to 180 ° C. A safety tire, characterized in that: 13. The composite according to claim 1, wherein the air bubble content of the composite is from 80.00% by volume to 98.%.
75% by volume of a safety tire.