JP2001294012A - Safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety tire providing stable traveling even when the tire is in a damaged state without sacrificing rolling resistance and comfortableness during normal traveling before the tire damage. SOLUTION: In this safety tire, foam with closed cells dispersed in a continuous phase comprising a high polymer body is arranged inside a hollow doughnut shaped tire. Internal pressure of the integrated cells of the foam is 200 kPa or more at 25 deg.C, and a high polymer body having a softening point at 80 to 180 deg.C is used as the high polymer body comprising the continuous phase.

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 Pneumatic tires contain air inside the tire and maintain a vacuum-based absolute pressure (hereinafter, simply referred to as an internal pressure) of about 200 to 400 kPa to form a tire skeleton such as a carcass and a belt of the tire. A tension is generated in the portion, and this tension enables deformation and restoration of the tire in response to an 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 so-called run flat tire having a flatness of 60% or less.

However, a technique for adding a side reinforcing layer is as follows.
Since the longitudinal spring constant and the longitudinal spring constant of the tire are 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 cross section and a flatness 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, which have a structure in which an internal support is arranged to support a load during puncturing, are mainly applied.

However, the tire cannot withstand local repeated input generated between the tire and the internal support during run flat after the puncture, and as a result, the mileage after the puncture is about 100 to 200 km. Was limited to. 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 the inside of the closed cells is at atmospheric pressure, all foams are not functionally sufficient to substitute high-pressure air in a normal tire.

[0010] Further, Japanese Patent No. 2987076 discloses a puncture tire in which a foam filler is inserted into an inner peripheral portion. 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. is there.

[0011]

Therefore, the present invention provides
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.

[0012]

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. It has been found that it is effective to provide a structure that does not allow gas to leak out of the device. That is, the gist configuration of the present invention is as follows.

(1) In a safety tire having a foam in which closed cells are dispersed in a continuous phase of a polymer inside a hollow donut-shaped tire, the internal pressure at 25 ° C. of the bubbles contained in the foam is arranged. Is 200 kPa or more, and the softening point of the polymer which is a continuous phase is 80 to 180 ° C.

(2) The safety tire according to (1), wherein the softening point of the polymer is 90 to 160 ° C.

(3) The safety tire according to (1) or (2), wherein the softening point of the polymer is 100 to 140 ° C.

(4) In any one of the above (1) to (3), the continuous phase of the foam 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.

(5) In any one of the above (1) to (4), the continuous phase of the foam comprises an acrylonitrile-based copolymer, and the acrylonitrile-based copolymer is an acrylonitrile polymer, an acrylonitrile / methacrylonitrile copolymer. A safety tire comprising at least one selected from a polymer, a methyl methacrylate / acrylonitrile copolymer and a methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer.

(6) In any one of the above (1) to (4), the continuous phase of the foam comprises an acrylic copolymer, and the acrylic copolymer comprises a methyl methacrylate resin, methyl methacrylate / acrylonitrile. A safety tire comprising at least one selected from a copolymer and a methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer.

(7) In any one of the above (1) to (4), the continuous phase of the foam comprises a vinylidene chloride-based copolymer, and the vinylidene chloride-based copolymer is
Acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate terpolymer and vinylidene chloride / methyl methacrylate / acrylonitrile /
Any one or two of methacrylonitrile copolymer
A safety tire characterized by being a seed.

(8) In any one of the above (1) to (4), the continuous phase of the foam comprises a nylon resin, and the nylon resin comprises nylon 6, nylon 11, nylon 1
2. Nylon 6/66 copolymer and nylon 6/12
A safety tire, which is at least one selected from copolymers.

(9) A safety tire according to any one of the above (1) to (4), wherein the continuous phase of the foam comprises a polyvinyl alcohol resin.

(10) In any one of the above (1) to (9), the continuous phase of the foam has a gas permeability resistance at 30 ° C. of 300 × 10 ⁻¹² (cc · cm / cm ² · s · cmH).
g) A safety tire characterized by the following.

(11) In any one of the above (1) to (10), the continuous phase of the foam has a gas permeability resistance at 30 ° C. of 20 × 10 ⁻¹² (cc · cm / cm ² · s · cmH).
g) A safety tire characterized by the following.

(12) In any one of the above (1) to (11), the continuous phase of the foam has a gas permeability resistance at 30 ° C. of 2 × 10 ⁻¹² (cc · cm / cm ² · s · cmHg). )
A safety tire characterized by the following.

(13) In any one of the above (1) to (12), propane and its fluorinated product, ethane fluorinated product, C4,5,6 linear and At least one selected from a branched aliphatic hydrocarbon, an alicyclic saturated hydrocarbon and a fluorinated product thereof;
A safety tire characterized by being filled with a kind of gas.

(14) The safety tire according to the above (13), wherein a fluorinated gas is enclosed at 50 mass% or more among the gas components in the closed cells of the foam.

(15) A safety tire according to any one of the above (1) to (14), wherein the expansion ratio of the foam is 10 to 80 times.

(16) In any one of the above (1) to (15), the tire has an inner liner layer on an inner peripheral surface thereof, and the inner liner layer is formed of a nylon resin having a softening point of 170 to 230 ° C. and isobutylene paraffin. The gelation rate of the elastomer component, including the methyl styrene copolymer halide, is 50%.
A safety tire comprising a thermoplastic elastomer composition dynamically vulcanized to about 95%.

(17) In the above (16), the inner liner layer has a gas permeation resistance at 30 ° C. of 20 × 10 ^−12.
(Cc · cm / cm ² · s · cmHg) or less.

[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 includes a foam 2 having closed cells disposed inside a tire 1. In addition,
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 automobile 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. In the drawings, reference numeral 7 denotes an inner liner layer, and reference numeral 8 denotes a rim.

The foam 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 foam 2 at 25 ° C. is 20
It is important that the pressure be 0 kPa or more, preferably 300 kPa or more. That is, if the internal pressure of the closed cells at 25 ° C. is less than 200 kPa, the deflection of the foam increases and the amount of repeated deformation during rolling of the tire increases,
The rate of progress of damage to the foam due to tire injury increases with the increase in the amount of deformation, and in this case also, the durability of the foam against repeated deformation is significantly reduced, and the performance when traveling in a tire damaged state is poor. Will be enough. 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 continuous phase in which the closed cells are dispersed in the foam 2 is formed of a polymer, and it is important to use a polymer having a softening point of 80 to 180 ° C. This is because, by regulating the softening point of the polymer, the foaming temperature of the foam can be controlled within a predetermined range, and a foam suitable for being arranged inside the tire can be obtained.

That is, there are various methods described below for arranging the foam inside the tire. Basically, the tire is foamed by heating the tire after filling the foamable composition inside the tire. Alternatively, it is fundamental to utilize the residual heat after vulcanization and foam the tire in a high temperature state while filling the tire with the foamable composition. Here, the foamable composition is obtained by dispersing, sealing, impregnating, or the like, a foaming agent made of a liquid that vaporizes under predetermined conditions or a compound that generates a gas by thermal decomposition in a continuous phase of a polymer. At normal temperature and normal pressure, foaming does not occur because vaporization is hindered by the rigidity and gas barrier properties of the continuous phase or the energy required for thermal decomposition is insufficient. When the tire is heated after filling the foamable composition inside the tire, the polymer and the foaming agent that become the continuous phase become active, and the foaming agent trapped in the polymer is vaporized or thermally decomposed. At the same time, the surrounding polymer is softened, and vaporization or thermal decomposition is further promoted, resulting in foaming. In particular,
Since the fluidization of the polymer in which the foaming agent has been confined is dominant to the foaming, it is possible to control the foaming time by regulating the softening point of the polymer.

Here, the internal temperature of the tire under conditions of use in the general market is about 50 to 60 ° C., but when the foam is filled inside the tire, the tire temperature further increases due to the heat storage characteristics of the foam. It is easy to guess. That is, if the softening point of the continuous phase is set too low,
There is a possibility that the temperature of the tire is higher than the softening point of the polymer constituting the continuous phase. When the temperature of the tire becomes higher than the softening point constituting the continuous phase, the continuous phase flows and the internal bubble structure is disturbed, leading to the communication of the bubbles and the significant deterioration of the gas permeability of the continuous phase. , The gas retention is reduced, so that the tire internal pressure is reduced, and the tire durability is impaired. Therefore, in order to reliably obtain the safety tire expected in the present invention in which the foam is disposed inside the tire, it is sufficient to avoid the above-mentioned problems.
It is important to use a polymer having a softening point in a temperature range of 0 ° C. or higher. On the other hand, since foaming is performed by heating a tire filled with the foamable composition inside, if the softening point of the polymer is increased, the heating temperature of the tire also needs to be increased. However, if the tire heating temperature is too high, the basic performance of the tire is not maintained due to deterioration of the rubber,
For this reason, a polymer having a softening point of 180 ° C. or lower is used. The softening point of the polymer is preferably 90 to 160 ° C, more preferably 100 to 140 ° C.
° C. In addition, the polymer which meets the above conditions will be described later.

By arranging the foam 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 foam 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. Therefore, since a proper internal pressure is applied to the tire by the foam 2, it is not necessary to regulate the tire structure itself, and a new safety tire can be provided by using a general-purpose tire and a general-purpose rim.

The tire in which the foam 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 damaged, a part of the foam 2 is damaged on the inner surface of the tire near the wound,
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. Therefore, the tire loses tension as a pressure vessel due to partial damage of the foam 2. Also, there is no puncture in the conventional pneumatic tire. Furthermore, since the probability that the foam 2 is damaged by the trauma of the tire is extremely low and the area of the damage is extremely limited, the internal pressure of the tire given by the foam 2 is reduced so as to impair the tire function. Is impossible.

In addition, although the vicinity of the damaged closed cell drops to the atmospheric pressure, the closed cells in the surrounding area have a pressure of 200 kP.
As a result of expansion due to having an internal pressure equal to or higher than a, the damaged closed cell region is compressed and the damaged portion is closed, so-called self-repair becomes possible.

Here, in order to provide a predetermined tire internal pressure with the foam 2, the gas sealed at a predetermined pressure in the closed cells in the foam 2 does not leak from the bubbles to the outside of the foam.
In other words, as described above, it is important that the matrix of the closed cells in the foam 2 has a property that gas is difficult to permeate. The phase is made of a material having low gas permeability resistance, specifically, acrylonitrile copolymer, acrylic copolymer, vinylidene chloride copolymer, acrylonitrile / styrene resin (AS), polyethylene resin (PE) , Polypropylene resin (PP),
It is preferable that the resin be made of at least one of polyester resin (PET), polystyrene / polyethylene copolymer (PS / PE), polyvinyl alcohol resin, nylon resin, diene rubber and butyl rubber. These materials are particularly effective for the present invention, because any of these materials can be easily formed into a foam in a tire and has flexibility against input due to tire deformation.

In particular, it is preferable to apply any one of an acrylonitrile copolymer, an acrylic copolymer, a vinylidene chloride copolymer, a nylon resin and a polyvinyl alcohol resin to the continuous phase of the foam. Further, as the acrylonitrile copolymer, at least one selected from acrylonitrile / methacrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer and methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer, acrylic As the copolymer, at least one selected from methyl methacrylate resin, methyl methacrylate / acrylonitrile copolymer and methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer, and as the vinylidene chloride-based copolymer, vinylidene chloride / Acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate terpolymer and vinylidene chloride / methyl Methacrylate / acrylonitrile / least 1 selected from methacrylonitrile copolymer
As the species and the nylon resin, at least one selected from nylon 6, nylon 11, nylon 12, nylon 6/66 copolymer and nylon 6/12 copolymer is advantageously suitable. These materials are
In any case, since the gas permeability resistance 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.

Next, the continuous phase of the foam has a gas permeation resistance at 30 ° C. of 300 × 10 ⁻¹² (cc · cm / cm ^2).
S · cmHg) or less, preferably a gas permeation coefficient at 30 ° C. of 20 × 10 ⁻¹² (cc · cm / cm ² •
s · cmHg) or less, more preferably 2 × 10 ⁻¹² (cc · cm / cm ² ···) at 30 ° C.
(s · cmHg) or less is recommended. This is because the gas transmission resistance of the inner liner layer in a normal pneumatic tire is 300 × 10 ⁻¹² (cc · cm / c).
m ² · s · cmHg) or less, taking into account the record of having a sufficient internal pressure holding function at a level of not more than 300 × 10 3 for the continuous phase of the foam.
^-12 (cc · cm / cm ² · s · cmHg) or less. However, at the level of this resistance to gas permeability coefficient, because it is necessary to pressure replenishment of about once every 3-6 months, in terms of its maintenance, 20 × 10 ^-12
(Cc · cm / cm ² · s · cmHg) or less, more preferably 2 × 10 ⁻¹² (cc · cm / cm ² · s · cm)
Hg) is recommended. In particular, 2 × 10
^At a level of ^-12 or less, it is possible to maintain a sufficient running internal pressure even if left for one year or three years.

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. Can be adjusted again, but when a polymer having a large gas permeation coefficient is used for the continuous phase, this refilling operation must be performed frequently, which is not practical.

The gas to be filled in the closed cells of the foam includes propane and its fluorinated product, ethane fluorinated product, linear and branched aliphatic hydrocarbons having 4, 5, 6 carbon atoms, and oils. At least one selected from cyclic saturated hydrocarbons and fluorinated compounds thereof is used. That is, at the time of resin matrix polymerization, for example, propane, butane, pentane, and the like are liquefied under high pressure and dispersed in a reaction solvent, and emulsion polymerization is performed, so that gas components such as propane, butane, and pentane are continuously maintained in a liquid state. When a material encapsulated by a matrix resin serving as a phase can be obtained, and filled with the tire in the form of a foam by heating, propane, butane, or pentane is sealed in bubbles. The isomers of butane and pentane include isobutane, isopentane and neopentane.

Further, the resin particles containing a liquefied gas such as propane, butane, and pentane are filled in a tire together with a melt of a matrix (continuous phase) forming a foam, and heated to form a foam. You can also get filled tires.

Since the above gases such as butane, isobutane, pentane, isopentane and neopentane are hydrocarbons, their solubility in rubber is relatively high, and the internal pressure of the bubbles gradually decreases with long-term use, and as a result, tires In some cases, the performance may deteriorate.In addition, since these gases are flammable at normal temperature and normal pressure, the products are shipped from the stage of loading and storing raw materials, not only in the process of manufacturing products. In all processes up to this point, it is necessary to comply with operational restrictions in equipment that pays close attention to ignition and explosion, which may impose a heavy burden on productivity.

In the case where there is such a concern, the internal pressure of the foam due to the above-mentioned use is increased by using a component composition containing an aliphatic fluorocarbon or a fluorohydrocarbon containing no chlorine as the foaming gas of the foam. And the problems caused by the flammability of the foaming gas can be eliminated. In other words, aliphatic fluorocarbons or fluorohydrocarbons that do not contain chlorine have a lower solubility in rubber as compared with general hydrocarbons due to fluorination. The pressure drop in the closed cell is slight, and there is an advantage that the internal pressure of the bubble and thus the internal pressure of the tire can be maintained for a long time. For example, even when the performance is improved by applying a rubber having a low heat generation or a rubber having a high gripping property to a tire, if the internal pressure of the tire decreases, the performance cannot be sufficiently exhibited in many cases. Applying this technology to such a problem means that the appropriate internal pressure is maintained for a long period of time, so that the reduction in the general performance of tires such as rolling resistance, steering stability and ride comfort is suppressed. Can be.

An aliphatic fluorocarbon or fluorocarbon containing no chlorine is nonflammable,
It is advantageous because problems such as ignition, dust and explosion at the raw material stage can be avoided, and even if it is dissipated in the atmosphere, it has no ozone decomposition effect.

Finally, the expansion ratio of the foam is 5 times or more and 5 times or more.
It is preferable to set it to 0 times or less. Because, when the expansion ratio is less than 5 times, when the foam is deformed inside the tire, stress is sporadically concentrated in the matrix portion between the bubbles, and cracks are easily generated in the matrix. The durability is significantly reduced. Conversely, if the foaming ratio exceeds 50 times, the degree of damage to the foam due to tire trauma will increase, and the speed of its growth will also increase, again in this case the durability of the foam against repeated deformation will be significantly reduced. .

The safety tire of the present invention is characterized in that the closed-cell internal pressure of the foam disposed in the inside is a high pressure which has not been achieved in the past. It depends greatly on the manufacturing method. Hereinafter, the manufacturing method will be specifically described.

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 continuous phase of the foam becomes a polymer constituting the foamable polymer composition.

The second technique is to melt a material to be a matrix (continuous phase) of a foam and add an organic foaming agent (including a foaming aid) to the inside of the tire assembly after assembling the rim. The tire assembly is then heated and foamed inside the tire.

A third technique is to inject butane, propane, pentane, or the like in a hollow polymer particle such as Expancel (trademark) and inject it into the tire assembly after the rim assembly. The tire assembly is heated to foam inside the tire. The continuous phase is a polymer constituting the hollow particles.

The fourth method is to melt a material to be a matrix (continuous phase) of a foam and to obtain a fluidity,
High pressure air or CO ₂ or N
Inject into the tire assembly with high pressure gas such as ₂
A foam is formed inside the tire assembly.

A fifth technique is to form a material serving as a matrix (continuous phase) of a foam into an annular shape, insert the material into the inside of a tire, incorporate the tire into a rim, and then build the tire assembly. Is heated to foam inside the tire. The matrix material does not necessarily need to be annular, but from the viewpoint of workability and uniform filling,
It is preferable to make it annular.

A sixth technique is to melt a resin matrix (continuous phase) that forms a foam by liquefying and encapsulating butane, propane, pentane and the like in polymer hollow particles such as Expancel (trade name). The material is filled together with the product into a rim-assembled tire, and then the tire assembly is heated as necessary to foam inside the tire.

In particular, when the foamed gas of the foam has a component composition containing chlorine-free aliphatic fluorocarbon or fluorohydrocarbon, each of the above methods can be used, but the following methods are applicable. . That is, in the seventh method, tetrafluoroethane, difluoroethane, fluoroethane, octafluoropropane, 2H-heptafluoropropane, decafluorobutane, cyclofluorobutane, dodecafluoropentane, and the like were liquefied and enclosed in polymer hollow particles. The material is poured into the tire assembly after the rim is assembled, and then the tire assembly is heated to foam inside the tire. In this case, the continuous phase of the foam is a polymer constituting the hollow particles.

In an eighth method, a continuous phase serving as a matrix of a foam is impregnated with the above-mentioned fluorocarbon or fluorohydrocarbon or the like, and injected into the tire assembly after the rim assembly, and the tire assembly is heated. To foam inside the tire.

A ninth method is to rim-assemble a fluorocarbon or a fluorohydrocarbon, particularly a high-content liquefied and encapsulated one, into the above polymer hollow particles together with a continuous phase matrix forming a foam. The inside of the tire is filled and then the tire assembly is heated as needed to foam inside the tire. Before filling the tire,
It is desirable to uniformly mix the polymer hollow particles and the continuous phase matrix in advance so that uniformity of foaming can be ensured. This technique is suitable especially when the continuous phase is a diene rubber and butyl rubber.

The continuous phase matrix includes an acrylonitrile copolymer, an acrylic copolymer, a vinylidene chloride copolymer, and an acrylonitrile / styrene resin (A
S), selected from polyethylene resin (PE), polypropylene resin (PP), polyester resin (PET), polystyrene / polyethylene copolymer (PS / PE), polyvinyl alcohol resin, nylon resin, diene rubber and butyl rubber At least one is suitable.

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 easy for the gas in the closed cells of the foam to remain in the cells.

The gelation ratio is defined as the Soxhlet extraction of the pelletized mixture after biaxial kneading with acetone in a water bath for 8 hours, and the residue is 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

Further, the inner liner layer is heated to 30 ° C.
Gas permeation coefficient of 20 × 10 ^-12 (Cc · cm /
cm^Two S · cmHg) or less. What
In other words, the matrix (continuous phase)
Even if the gas permeability is poor, the inner liner layer
If the gas permeation resistance of the foam is good,
Leakage to the outside of the tire can be suppressed, and the tire's internal pressure
This is because it is advantageous to hold In other words, the inner
-The superiority of the liner layer's gas permeation resistance depends on the tire pressure.
It is a factor that directly determines the pressure retention as a force vessel.
Because Of course, the matrix (foam)
Basically, it is excellent in gas permeation resistance of
In addition, the inner liner layer has excellent gas permeability resistance
It is ideal to use

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.

[0063]

EXAMPLE A foam tire having various specifications shown in Tables 1 and 2 was applied to a tire having the structure shown in FIG. 1 or 2 as shown in the same table, and a passenger car safety tire of size 205 / 60R16 was prototyped. did. Here, the tire 1 conforms to the general structure of the type and size of the tire. Table 1
Tables 3 and 4 show the contents of the expandable polymer composition and the additives in Examples 2 and 3, and similarly, Table 5 shows the rubber type of the inner liner layer.

Next, the tire deflection before and after running the drum with 5000 km and a load of 4.58 kN was measured for the tire with the internal pressure adjusted and the tire filled with the foam, and the deflection before running of each tire was 10%.
The index when it was set to 0 was determined for each tire. The larger the index is, the higher the internal pressure holding performance is, indicating a good result.

Each of the tire / rim assemblies after running the drum is mounted on a 2000 cc class passenger car, and then a nail having a diameter of 3 mm and a length of 3 cm is penetrated from the outside of the tire tread into the tread. After the injury was caused, a load corresponding to four passengers was applied, the test course was run at 90 km / h, a maximum of 300 km was traveled, and the possible travel distance was measured.
The criterion was that a travel distance of 200 km or more was accepted. The results of these surveys are shown in Tables 1 and 2.

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

In Comparative Example 3, the softening point was 195 ° C.
Filled with a foamable polymer composition having a continuous phase of
It was necessary to apply a temperature of 200 ° C. or more to cause foaming. For this reason, thermal aging of the tire itself was accelerated, and although a tire filled with a foam was obtained, the durability of the tire was remarkably reduced, so that various tests could not be performed.

[0072]

According to the present invention, a safety tire capable of running stably 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 foam 3 bead core 4 carcass 5 belt 6 tread 7 inner liner layer 8 rim 9 side reinforcing layer

Claims (17)

[Claims] 1. In a safety tire having a foam in which closed cells are dispersed in a continuous phase of a polymer inside a hollow donut-shaped tire, an internal pressure at 25 ° C. of bubbles built in the foam is set. A safety tire characterized in that the polymer has a softening point of at least 200 kPa and a softening point of 80 to 180 ° C. which is a continuous phase. 2. The safety tire according to claim 1, wherein the softening point of the polymer is 90 to 160 ° C. 3. The safety tire according to claim 1, wherein the softening point of the polymer is 100 to 140 ° C. 4. The method according to claim 1, wherein
The continuous phase of the foam is an acrylonitrile copolymer, an acrylic copolymer, a vinylidene chloride 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. 5. The method according to claim 1, wherein
The continuous phase of the foam comprises an acrylonitrile-based copolymer, and the acrylonitrile-based copolymer is an acrylonitrile polymer, an acrylonitrile / methacrylonitrile copolymer, a methyl methacrylate / acrylonitrile copolymer, and a methyl methacrylate / acrylonitrile /
A safety tire comprising at least one member selected from methacrylonitrile terpolymers. 6. The method according to claim 1, wherein
The continuous phase of the foam comprises an acrylic copolymer, which is selected from methyl methacrylate resin, methyl methacrylate / acrylonitrile copolymer and methyl methacrylate / acrylonitrile / methacrylonitrile terpolymer. A safety tire comprising at least one of the following: 7. The method according to claim 1, wherein
The continuous phase of the foam is composed of a vinylidene chloride-based copolymer,
The vinylidene chloride-based copolymer includes vinylidene chloride / acrylonitrile copolymer, vinylidene chloride / methyl methacrylate copolymer, vinylidene chloride / acrylonitrile / methyl methacrylate terpolymer and vinylidene chloride / methyl methacrylate / acrylonitrile / methacrylonitrile copolymer. A safety tire characterized by being one or two kinds of polymers. 8. The method according to claim 1, wherein
The continuous phase of the foam is made of a nylon resin, and the nylon resin is nylon 6, nylon 11, nylon 12,
A safety tire characterized in that it is at least one selected from nylon 6/66 copolymer and nylon 6/12 copolymer. 9. The method according to claim 1, wherein
A safety tire wherein the continuous phase of the foam is made of a polyvinyl alcohol resin. 10. The foam according to claim 1, wherein the continuous phase of the foam has a gas permeability resistance of 300 × 10 ⁻¹² (cc · cm / cm ² · s · cmH at 30 ° C.).
g) A safety tire characterized by the following. 11. The foam according to claim 1, wherein the continuous phase of the foam has a gas permeability resistance at 30 ° C. of 20 × 10 ⁻¹² (cc · cm / cm ² · s · cmH).
g) A safety tire characterized by the following. 12. The continuous phase of the foam according to any one of claims 1 to 11, wherein the gas permeation coefficient at 30 ° C. is 2 × 10 ⁻¹² (cc · cm / cm ² · s · cmHg).
A safety tire characterized by the following. 13. The closed cell of the foam according to claim 1, wherein propane and its fluorinated product, ethane fluorinated product, linear and branched aliphatic having 4, 5, 6 carbon atoms are contained in the closed cells of the foam. Hydrocarbon, and at least one selected from alicyclic saturated hydrocarbons and fluorinated compounds thereof
A safety tire characterized by being filled with a kind of gas. 14. The safety tire according to claim 13, wherein a fluorinated gas is sealed at 50 mass% or more among gas components in closed cells of the foam. 15. The safety tire according to claim 1, wherein the foam has a foaming ratio of 10 to 80 times. 16. The tire according to claim 1, further comprising an inner liner layer on the inner peripheral surface of the tire, wherein the inner liner layer is formed of a nylon resin having a softening point of 170 to 230 ° C. and isobutylene paramethylstyrene. The gelation rate of the elastomer component including the unified halide is 50%.
A safety tire comprising a thermoplastic elastomer composition dynamically vulcanized to about 95%. 17. The inner liner layer according to claim 16, wherein the gas permeation resistance at 30 ° C. is 20 × 10
^-12 (cc · cm / cm ² · s · cmHg) or less.