JP2002079805A - Safety tire, foam acrylonitrile polymer composition used therefor, and manufacturing method of safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety tire enabling stable traveling even in a flawed condition of a tire without sacrificing rolling resistance and ride comfort during normal traveling before the tire flaws. SOLUTION: A composite comprised of continuous phase of resin and independent bubbles is arranged inside of hollow doughnut-like tire. A bubble content by percent of the composite is 80.00 to 98.75 vol.%, internal pressure of the bubbles at 25 deg.C is controlled below 150 kPa, and the continuous phase of the composite is made of acrylonitrile polymer.

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, a tire for a passenger car, air is sealed in the tire and an absolute pressure based on a vacuum (hereinafter, simply referred to as an internal pressure) is 250 to 350 k.
While maintaining the pressure at about Pa, a tension is generated in the tire skeleton such as a carcass and a belt of the tire.
Deformation of the tire and its restoration are made possible in response to the input to the tire. 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] By the way, if the tire maintained at the predetermined internal pressure receives an injury, air leaks out through the injury and the tire internal pressure decreases to the atmospheric pressure, resulting in a so-called puncture state. Most of the tension generated in the part is lost. Then, as a result of losing the load support function, driving, braking and turning performance obtained by applying a predetermined internal pressure to the tire,
The vehicle equipped with the tires becomes unable to run.

[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. And since all foams have low expansion ratios, they have a large weight in spite of having air bubbles, inevitable deterioration of ride comfort and fuel efficiency, and the inside of the closed cells is at atmospheric pressure. It was not functionally sufficient to substitute high pressure air for tires.

[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 compounding material is used as an inflation pressure foam, and after arranging a large number of these inside the tire and 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 is naturally exhausted from the exhaust holes formed 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 normal temperature is 400
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. On the other hand, inside the tire and rim assembly, a large number of inflated pressure bubbles wrapped in the soft elastic outer coating are arranged, but the friction between the soft elastic outer coatings in which the blown occurs, the inner surface of the tire and the inner surface of the rim. There is a great problem in terms of durability, such as friction with the tire. From the above, it can be said that the above problem is a major drawback caused by arranging a large number of divided expansion pressure bubbles, unlike the case where the shape of the expansion pressure bubbles takes an integral donut shape.
In addition, although the exhaust holes formed in the rim are effective for naturally exhausting the normal pressure air inside the tire due to the expansion of the inflation pressure bubbles, the exhaust holes and the gas passages in the inflation pressure bubbles are dissipated. Therefore, it cannot be used for a long time.

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 and a method of manufacturing the same that enable stable running even after a tire is injured without sacrificing rolling resistance and riding comfort during normal running.

Another object of the present invention is to provide a foamable polymer composition to be used as a material for filling the inside of the safety tire.

[0017]

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 and closed cells is arranged inside a hollow donut-shaped tire, the composite has a bubble content of 80.00% by volume to 98.75% by volume. %, And 2 of the built-in closed cells
The internal pressure at 5 ° C. is 150 kPa or more in absolute pressure;
The safety tire according to claim 1, wherein the continuous phase includes a continuous phase made of an acrylonitrile-based polymer.

(2) In the above (1), the acrylonitrile-based polymer may be a homopolymer of an acrylonitrile-based monomer, a copolymer of an acrylonitrile-based monomer, or an acrylonitrile-based polymer having an acrylonitrile-based monomer content of 20% by weight or more. A safety tire characterized in that it is at least one member selected from the group consisting of a copolymer of a monomer and methyl methacrylate and / or vinylidene chloride, and has a glass transition point of 80 ° C. or higher.

(3) In the above (1) or (2),
A safety tire characterized in that the acrylonitrile-based polymer is obtained by radical polymerization.

(4) In any one of the above (1) to (3), nitrogen, air, a fluorinated ethane, a linear aliphatic hydrocarbon having 3 to 8 carbon atoms, and The fluorinated product, the branched aliphatic hydrocarbon having 3 to 8 carbon atoms and the fluorinated product,
A safety tire, comprising at least one gas selected from the group consisting of alicyclic hydrocarbons and their fluorinated compounds.

(5) In any one of the above items (1) to (4), the weight fraction of the ethane fluoride and / or propane to the total gas amount in the bubbles of the composite is 1
A safety tire characterized by being at least 0% by weight.

(6) The rim is incorporated into the tire, and a predetermined amount of the expandable acrylonitrile-based polymer composition obtained by radical polymerization is disposed inside the tire, and then heated, so that the inside of the hollow donut-shaped tire is heated. A method for producing a safety tire, comprising forming a composite having closed cells.

(7) In the above (6), the foamable acrylonitrile-based polymer composition comprises an acrylonitrile-based polymer, a fluorinated product of nitrogen, air, and ethane, and a linear aliphatic carbon having 3 to 8 carbon atoms. Hydrogen and its fluorinated product, a branched aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, alicyclic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, and nitrogen and / or dioxide A method for manufacturing a safety tire, comprising at least one foaming component selected from the group of pyrolytic foaming agents that generate carbon.

(8) Acrylonitrile polymer, fluorinated product of nitrogen, air and ethane, linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, branched fat having 3 to 8 carbon atoms At least one selected from the group consisting of an aromatic hydrocarbon and a fluorinated product thereof, an alicyclic hydrocarbon having 3 to 8 carbon atoms and a fluorinated product thereof, and a pyrolytic blowing agent which generates nitrogen and / or carbon dioxide by thermal decomposition. A foamable acrylonitrile-based polymer composition comprising a kind of foaming component.

[0026]

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 made of resin and closed cells arranged inside a tire 1. 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.

The composite 2 has closed cells in which individual cells are isolated by being surrounded by partition walls. The composite 2 has a cell content of 80.00% by volume to 90.00% by volume.
It is important to set the internal pressure at 8.75% by volume and the closed cells at 25 ° C. to 150 KPa or more. 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. The durability of the composite is significantly reduced. On the other hand, if 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 increased. This is because it is significantly reduced.

Here, the bubble content is a percentage of the volume of the bubble to the volume of the composite arranged in the tire, and can be calculated by the following equation. . Air bubble content = {1− (use volume of resin or composition constituting composite / volume of tire)} × 100 where “the volume of use of resin or composition constituting composite” in the above formula Refers to the volume of the composition before the formation of closed cells by foaming by heating or the like, and is a volume value that does not include 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.

Similarly, if the internal pressure of the closed cells at 25 ° C. is less than 150 kPa, the flexure of the composite becomes large and the amount of repetitive deformation during rolling of the tire becomes large. In addition to the increase in the history, the rate of development of damage to the composite due to tire trauma increases with the increase in the amount of deformation, and also in this case, the durability of the composite against repeated deformation significantly decreases, and The running performance becomes insufficient.

Here, the following method can be used as a device for maximizing the durability of the composite used in the present invention. That is, during normal running (before tire damage)
200-300 kPa between the complex and the tire inner surface
Filling a certain amount of air actively compresses the complex in 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 charged air between the composite and the inner surface of the tire is dissipated due to the tire damage, the running performance in the tire damaged state is greatly improved as compared with the case where the above method is not adopted.

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.

The tire in which the composite 2 is disposed inside is characterized in that even if the tire is injured, the tension of a case such as a normal pneumatic tire does not easily decrease. 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, the vicinity of the damaged closed cell drops to the atmospheric pressure, but the closed cells around the damaged closed cell have a pressure of 150 kP.
As a result of instantaneous expansion due to having an internal pressure of a or more,
The region of the damaged closed cell is compressed and the damaged portion is instantly closed, so that self-repair becomes possible.

Here, in order to give a predetermined tire pressure by 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 important that the continuous phase of the closed cells in the composite 2 has a property that the gas does not easily permeate. That is, it is important that the continuous phase of the composite 2 be made of a material having low gas permeability, specifically, a continuous phase made of an acrylonitrile-based polymer. The acrylonitrile-based polymer is particularly effective for the present invention because it can be easily formed into a composite in a tire and has flexibility against input due to tire deformation.

The acrylonitrile polymer includes:
Selected from the group consisting of homopolymers of acrylonitrile monomers, copolymers of acrylonitrile monomers, and copolymers of acrylonitrile monomers with methyl methacrylate and / or vinylidene chloride having an acrylonitrile monomer content of 20% by weight or more. It is advantageous that at least one of them is suitable and has a glass transition point of 80 ° C. or higher. That is, these materials
In any case, since the gas permeability coefficient is small and the gas permeability is low, 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. Here, the acrylonitrile monomer refers to acrylonitrile and methacrylonitrile.

The temperature inside the tire varies depending on the use conditions, but is about 60 to 70 ° C. in general running. In general, the gas permeation coefficient of a polymer has temperature dependence, and the gas permeation coefficient gradually increases in a temperature region beyond the glass transition point of the polymer. Therefore, by selecting a polymer having a glass transition point at a temperature higher than the use temperature inside the tire, the gas permeability of the polymer can be fully exerted.

The continuous phase of the composite may be composed of an acrylonitrile polymer alone, or may be a mixture with other materials. In that case, as the other material, a material having low gas permeability like the acrylonitrile-based polymer is appropriate, and specifically, a polyvinyl alcohol resin, an acrylic polymer, a vinylidene chloride-based polymer,
It is recommended to consist of at least one of a nylon resin 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 use any one of a polyvinyl alcohol resin, an acrylic polymer and a vinylidene chloride polymer. Further, as the acrylic polymer, methyl methacrylate resin (MMA), methyl methacrylate / acrylonitrile copolymer (MMA)
/ AN) and methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer (MMA / AN)
/ MAN), and the vinylidene chloride-based polymer includes vinylidene chloride / acrylonitrile copolymer (PVDC / AN) and vinylidene chloride / methyl methacrylate copolymer (PVDC / MM).
A), vinylidene chloride / methacrylonitrile copolymer (PVDC / MAN), vinylidene chloride / acrylonitrile / methacrylonitrile terpolymer (PVDC /
AN / MAN), vinylidene chloride / acrylonitrile /
Methyl methacrylate terpolymer (PVDC / AN /
MMA) and / or at least one vinylidene chloride / acrylonitrile / methacrylonitrile / methyl methacrylate quaternary copolymer (PVDC / AN / MAN / MMA) are each advantageously suitable. All of these materials have a small gas permeability coefficient and low gas permeability, so that even if they are mixed in a continuous phase, the gas in the closed cells does not leak to the outside, and the internal pressure of the closed cells is set to a predetermined value. Can be kept in range.

The continuous phase of the composite 2 obtained using the above materials has a gas permeability coefficient of 300 × 10 3 at 30 ° C.
^-12 (cc · cm / cm ² · s · cmHg) or less, preferably a gas permeability coefficient at 30 ° C of 20 × 10
^-12 (cc · cm / cm ² · s · cmHg) or less, more preferably a gas permeability coefficient at 30 ° C of 2 × 10 ^-12
(Cc · cm / cm ² · s · cmHg) or less is recommended. This is because the gas permeability coefficient of the inner liner layer in a normal pneumatic tire is 300 × 10 ^−1
2 (cc · cm / cm ² · s · cmHg) or less, in view of the record of having a sufficient internal pressure holding function, the continuous phase of the composite 2 also has a gas permeability coefficient of 300 at 30 ° C. ^{× 10 -12 (cc · cm /} cm 2 · s · cm
Hg) or less. However, at this level of the gas permeability coefficient, internal pressure replenishment is required about once every 3 to 6 months.
10 ^-12 (cc · cm / cm ² · s · cmHg) or less
More preferably, 2 × 10 ⁻¹² (cc · cm / cm ² · s)
CmHg) or less is recommended.

The gas to be filled in the closed cells of the composite is nitrogen, air, fluorinated ethane, a linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, and 3 to 8 carbon atoms. At least one selected from the group consisting of 8 branched aliphatic hydrocarbons and fluorinated products thereof, and alicyclic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof is used. The method for forming a composite having closed cells is not particularly limited, but it is preferable to use a foaming agent. Examples of the foaming agent include a high-pressure compressed gas and a liquefied gas, in addition to a pyrolytic foaming agent that generates a gas by thermal decomposition. In particular, many thermally decomposable blowing agents have a characteristic of generating nitrogen, and a composite obtained by appropriately controlling the reaction has nitrogen in bubbles.

Many of the pyrolytic foaming agents have a characteristic of generating nitrogen by thermal decomposition, and the foam obtained by appropriately controlling the reaction has nitrogen in the cells. 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. By encapsulating these thermally decomposable foaming agents in a molten continuous phase, a desired composite can be obtained. On the other hand, when the resin continuous phase forming the composite is melted and filled into the tire at a high pressure together with air and nitrogen to form the composite, air and nitrogen remain in the bubbles.

When the above resin continuous phase is polymerized, fluorinated ethane, a linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, and a branched C3 to C8 aliphatic hydrocarbon under high pressure. Aliphatic hydrocarbons and their fluorides,
And an alicyclic hydrocarbon having 3 to 8 carbon atoms and a fluorinated product thereof, specifically, propane, butane, pentane, hexane, heptane, octane, cyclopropane,
There is also a method of liquefying cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, and the like and dispersing them in a reaction solvent, and emulsion-polymerizing the resulting mixture.Propane, butane, pentane, hexane, heptane, octane, cyclopropane, cyclobutane The particles of the expandable polymer composition in which gas components such as cyclopentane, cyclohexane, cycloheptane and cyclooctane are encapsulated in a liquid state in the above resin continuous phase can be obtained, and this is filled into a tire and heated. In the case of a composite, propane, butane, pentane,
Hexane, heptane, octane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane and the like are encapsulated. The isomers of butane, pentane, hexane, heptane and octane include isobutane, isopentane, neopentane, 2-methylpentane, 2,2-dimethylbutane,
Examples thereof include methylhexanes, dimethylpentanes, trimethylbutane, methylheptanes, dimethylhexanes, and trimethylpentanes. Furthermore, the particles of the expandable polymer composition containing the liquefied gas are filled in a tire together with a melt of the resin continuous phase forming the composite, and the composite is arranged therein by heating. You can also get tires.

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

The safety tire of the present invention is characterized in that the pressure inside the closed cell of the composite disposed particularly is higher than ever before. The realization of such a safety tire is as follows. It largely depends on new manufacturing methods.
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 a predetermined amount of the expandable polymer composition is charged into the tire, the tire is mounted on 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 method is to melt a material to be a continuous phase of a composite, add a foaming agent (including a foaming aid) to the material, and inject the material into the tire assembly after the rim assembly. Next, the tire assembly is heated to foam inside the tire.

A third technique is to form particles of an expandable polymer composition in which butane, propane, pentane, or the like is liquefied and enclosed in polymer particles, such as Expancel (trademark), for example. Pour into the tire assembly, then heat the tire assembly and foam inside the tire.

The fourth technique is to melt the raw material to be the continuous phase of the composite and, in a state where fluidity has appeared, put high-pressure air or high-pressure gas such as CO ₂ or N _{2 in} the tire after the rim is assembled. At the same time, the mixture is injected into the tire assembly to form a composite inside the tire assembly.

A fifth technique is to form a predetermined amount of an expandable polymer composition into an annular shape, insert the inside into a tire, then mount the tire on a rim, and then heat the tire assembly. Then, foaming is performed inside the tire. In addition,
The foamable polymer composition does not necessarily need to be annular, but is preferably annular from the viewpoint of workability and uniform filling.

The sixth technique is to use butane, propane, or the like in polymer particles, such as Expancel (trade name).
The particles of the expandable polymer composition in which pentane or the like is liquefied and sealed are filled together with the melt of the material to be the continuous phase of the composite into the rim-assembled tire, and then the tire assembly is heated if necessary. Then, foaming is performed inside the tire.

The seventh method is to heat and expand particles of an expandable polymer composition in which butane, propane, pentane, or the like is liquefied and enclosed in polymer particles, such as Expancel (trade name). The spherical particles are filled into the tire and rim assembly. In this case, the continuous phase of the composite refers to the polymer constituting the shell of the particle.

The continuous phase has an acrylonitrile polymer as a main component and a combination of at least one polymer selected from polyvinyl alcohol resin, acrylic polymer, vinylidene chloride polymer, nylon resin and butyl rubber. be able to. 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 melting point of 170 to 230 ° C. and a halogen of isobutylene paramethylstyrene copolymer. Comprising a thermoplastic elastomer composition obtained by dynamically vulcanizing an elastomer component containing a fluoride to a gelation ratio of 50 to 95%,
preferable. 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 permeability becomes extremely low, so that the function of the inner liner layer can be enhanced. Further, an elastomer component containing a halide of isobutylene paramethylstyrene copolymer is gelled at a gelation ratio of 50 to 95%.
By dynamically vulcanizing the thermoplastic elastomer composition, an inner liner layer having high flexibility and excellent heat resistance and durability can be obtained. The inner liner layer having the above characteristics can create an environment that facilitates 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 ratio (%) = [weight of all formulations-{(extracted amount of acetone + extracted amount of n-hexane) -amount of stearic acid}] / weight of all formulations × 100

[0056] 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. Even if the gas in the air bubbles leaks out of the composite for some reason, if the gas permeability of the inner liner layer is sufficiently low, the gas in the air bubbles in the composite leaks out of the tire. This is because it is less likely to come out, which is advantageous for maintaining the internal pressure of the tire. That is, 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.

FIG. 1 shows the application of the composite to a general-purpose tire. However, for example, as shown in FIG. 2, the composite can be applied to a tire having a structure suitable for a run flat. . 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.

[0058]

EXAMPLE A tire having the structure shown in FIG.
Applying the complex of various specifications shown in the table as shown in the table,
Built into a rim of size 6.0J × 15, size 205
/ 60R15 safety tire for passenger cars was prototyped. Here, the tire 1 conforms to the general structure of the type and size of the tire. In Tables 1 and 2, the types and contents of the foamable polymer composition constituting the composite are shown in Table 3.
Similarly, Table 4 shows the rubber type of the inner liner layer, and Table 5 shows the compounding of the side reinforcing rubber.

The pressure in the bubble shown in Tables 1 and 2 was calculated by the following equation (A) based on the following definition. 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

For each of the tires thus obtained, 50
The amount of deflection of the tire was measured before and after running the drum under the condition of 00 km and a load of 4.41 KN, and the amount of deflection change before and after the running of the drum (the tire height before running under the load-the tire after running under the load). Height) is shown as an index when the tire height before running under the load of each tire is set to 100. This index is defined as a deflection increase rate, and the smaller the index is, the better the result is.

Further, the tire after running the drum is
Attached to a 0cc class passenger car, then diameter: 3
mm and length: Injured by passing a 3 cm nail through the tread from outside the tire tread, then 4
Apply a load equivalent to the name of the rider and set the test course to 9
The vehicle traveled at a maximum of 500 km while traveling at 0 km / h, and the travelable distance was measured. 200k mileage
m or more was regarded as a pass. The results of these surveys are shown in Tables 1 and 2.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

[Table 4]

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

Next, according to the description of the above-mentioned Japanese Patent Application Laid-Open No. 48-70002, a tire disclosed in the same patent was manufactured. That is, when a large number of the closed-cell-forming compound raw materials are placed inside the tire / rim assembly and vulcanization molding is performed, the pressure generated by the foaming of the closed-cell-forming compound raw materials in the heating step is small. A blown phenomenon occurred in the elastic outer coating. This blown phenomenon is a general defect found in the vulcanization process of rubber products in which bubbles are generated by volatile components in the compounding raw materials, and is mainly caused by insufficient pressure. In addition, since the inside of the inflated pressure foam wrapped in the soft elastic envelope film was foamed by the raw material for forming closed cells, it was not possible to confirm the occurrence of the blown phenomenon.

Next, a load test and a rolling load were applied to the foam-filled tire obtained above, and a running test was performed with an indoor drum tester. After running about 100 km, the inside of the tire was observed. The expanded pressure bubbles wrapped in a large number of soft elastic outer coatings were in a separated state.
From these observations, it was found that peeling occurred due to bubbles due to the blown phenomenon in the soft elastic outer coating film of the expanded pressure foam, and this resulted in separation.

Further, the above foam-filled tire is 1000 k
m, it was confirmed that all of the expanded pressure bubbles wrapped in the large number of soft elastic outer coatings were separated. Furthermore, from the surface observation of the expanded pressure foam,
The occurrence of wear due to friction between the peeled surfaces was also confirmed.

When the rolling resistance of the tire after traveling 1000 km was measured in comparison with a normal tire to which internal pressure was applied by a tube, the result was significantly inferior. It was found to increase with each increase. The two factors involved are energy loss due to frictional heat generated between the peeled surfaces, which was found in the above observations, and a decrease in the internal pressure holding function of the soft elastic outer coating due to abrasion. , Frictional destruction of the soft elastic outer coating due to running, reduced internal pressure holding function of the soft elastic outer coating due to wear, dissipation of gas from rim exhaust holes,
It can be concluded that the energy loss due to the frictional heating between the peeled surfaces caused the rolling resistance to be significantly deteriorated.

[0071]

According to the present invention, there is provided a safety tire which enables stable running even in a tire-damaged state without sacrificing rolling resistance and riding comfort during normal running before the tire is damaged. 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

Claims (8)

[Claims] 1. A safety tire in which a composite composed of a continuous phase and closed cells is arranged inside a hollow donut-shaped tire, wherein the composite has a bubble content of 80.00% to 98.75% by volume. And 25 of the built-in closed cells
A safety tire having an internal pressure at 150 ° C. of 150 kPa or more in absolute pressure, wherein the continuous phase includes a continuous phase composed of an acrylonitrile-based polymer. 2. The acrylonitrile-based polymer according to claim 1, wherein the acrylonitrile-based polymer is a homopolymer of an acrylonitrile-based monomer,
A copolymer of an acrylonitrile-based monomer, and a content of the acrylonitrile-based monomer of 20% by weight or more;
A safety tire comprising at least one member selected from the group consisting of a copolymer of an acrylonitrile monomer and methyl methacrylate and / or vinylidene chloride, and having a glass transition point of 80 ° C. or higher. 3. The safety tire according to claim 1, wherein the acrylonitrile-based polymer is obtained by radical polymerization. 4. The method according to claim 1, wherein
In the bubbles of the composite, nitrogen, air, fluorinated ethane, a linear aliphatic hydrocarbon having 3 to 8 carbon atoms and its fluorinated product, a branched aliphatic hydrocarbon having 3 to 8 carbon atoms and the same A safety tire comprising a fluorinated product and at least one gas selected from the group consisting of an alicyclic hydrocarbon having 3 to 8 carbon atoms and a fluorinated product thereof. 5. The method according to claim 1, wherein
A safety tire characterized in that the weight fraction of fluorinated ethane and / or propane is 10% by weight or more with respect to the total gas amount in bubbles of the composite. 6. A rim is incorporated in a tire, a predetermined amount of an expandable acrylonitrile polymer composition obtained by radical polymerization is disposed inside the tire, and the rim is heated so that the acrylonitrile-based polymer composition becomes independent inside the hollow donut-shaped tire. A method for producing a safety tire, comprising forming a composite having bubbles. 7. The foamable acrylonitrile-based polymer composition according to claim 6, wherein the acrylonitrile-based polymer composition comprises:
Nitrogen, air, fluorinated 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, having 3 to 8 carbon atoms 8 and a fluorinated product thereof, and at least one foaming component selected from the group of thermally decomposable blowing agents that generate nitrogen and / or carbon dioxide by thermal decomposition. Manufacturing method of safety tire. 8. An acrylonitrile polymer, a fluorinated product of nitrogen, air, and ethane, a linear aliphatic hydrocarbon having 3 to 8 carbon atoms and a fluorinated product thereof, and a branched aliphatic having 3 to 8 carbon atoms. Hydrocarbons and their fluorides,
At least one selected from the group consisting of alicyclic hydrocarbons having 3 to 8 carbon atoms and fluorinated products thereof, and a pyrolytic blowing agent that generates nitrogen and / or carbon dioxide by pyrolysis.
A foamable acrylonitrile-based polymer composition comprising a kind of foaming component.