JP4990485B2 - Tire and rim assembly and hollow particles arranged inside the assembly - Google Patents

Description

  The present invention relates to an assembly of a tire and a rim that safely and reliably realizes a minimum movement from a punctured state after being damaged to a place where tire repair can be performed. In particular, it can be realized by combining a general-purpose tire and a general-purpose rim, and is excellent in durability, ride comfort, fuel saving and versatility in regular running before tire damage, and at low cost without sacrificing productivity. The present invention relates to an assembly of a tire and a rim that can provide driving safety during puncture.

  In pneumatic tires, for example, passenger car tires, air is contained in the tire chamber under a pressure of about 150 kPa to 250 kPa as a gauge pressure, and tension is generated in the tire skeleton such as the carcass and belt of the tire. Therefore, the tire can be deformed and restored in response to the input to the tire. That is, by maintaining the internal pressure of the tire chamber within a predetermined range, a constant tension is generated in the tire skeleton to provide a load support function and increase the rigidity, driving, braking, turning performance, etc. The basic performance necessary for driving the vehicle is given.

  By the way, when the tire held at the predetermined internal pressure is damaged, high pressure air leaks to the outside through the external damage, and the tire internal pressure is reduced to the atmospheric pressure. Most of the tension that was generated in the process will be lost. As a result, the load support function and the driving, braking, and turning performance obtained by applying a predetermined internal pressure to the tire are also lost. As a result, the vehicle equipped with the tire cannot run.

  Therefore, many proposals have been made on so-called safety tires that can travel even in a puncture state. For example, as pneumatic safety tires and rim assemblies for automobiles, there are various types such as those having a double wall structure, those having a load support device disposed in the tire, and those having reinforced tire side portions. Proposed. Of these proposals, the technology that is actually used is to provide a crescent-shaped side reinforcement layer made of a relatively hard rubber on the inner surface from the shoulder to the bead, centering on the tire sidewall. This method is mainly applied to so-called “run-flat tires” having an aspect ratio of 60% or less.

  However, the method of adding a side reinforcing layer increases the tire weight by 30% to 40% and also increases the tire hysteresis loss, so that deterioration in fuel efficiency due to a significant deterioration in rolling resistance is inevitable. Furthermore, the increase in the tire weight leads to an increase in the unsprung weight of the vehicle, which is disadvantageous in combination with an increase in the tire spring constant and a decrease in riding comfort during normal driving. Further, since the driving input to the suspension increases due to the increase in the tire spring constant, a design change is required to improve the durability of the undercarriage of the vehicle. Therefore, when the tire is mounted on an existing vehicle for repair, there is a risk of causing a failure because the durability of the undercarriage is insufficient. In addition, when run flat after puncture, heat aging occurs due to self-heating of the side reinforcement layer, so reuse by repairing the puncture damage part cannot be basically handled and must be discarded. From this point of view, it is still a technology with poor versatility.

  On the other hand, for pneumatic tires with a high tire cross-section and a flatness ratio of 60% or more, internal support such as a core is provided on the rim to avoid heat generation at the sidewalls due to relatively high speed and long distance running. A run-flat tire has been proposed in which the body is fixed to support the load during puncture.

However, the tire cannot withstand repeated local input that occurs between the tire and the internal support during the run-flat after puncture, and as a result, the mileage after puncture is limited to about 100 to 200 km. ing. In addition, since the tire and the inner support body are greatly damaged by the run-flat running after the puncture, the reusability is low and the disadvantage from the viewpoint of economy and environmental load cannot be denied.
In addition, the work of assembling the tire on the rim after the internal support is arranged inside the tire is also troublesome and takes a long time. In this regard, a device has been proposed that makes it easy to insert the internal support by providing a difference in the rim diameter between one end and the other end in the width direction of the rim, but a special dedicated rim assembly machine is required. Since infrastructure redevelopment and special training for assembly workers are indispensable, it is still lacking in versatility and there are many issues in providing services. Further, since the total weight increases by 30 to 40% due to the addition of the internal support compared to the conventional tire and rim assembly, there is a disadvantage similar to that of the above-described side reinforcement type.

  In order to extend the mileage after puncture of the side reinforcement type and the type with internal support, it is possible to add a skeleton material to make the tire structure more heavy, but it is usually used as the skeleton material is added Adopting this method is not practical because the rolling resistance and ride comfort of the time are further deteriorated.

  On the other hand, there are means that do not deteriorate the performance in normal running as the above-mentioned side reinforcement type and internal support type, although the response force against the internal pressure drop due to tire damage and the running ability after puncture are not sufficient.

  The first is a sealant tire. A highly adhesive layer is disposed on the inner surface of the tire, and when the foreign matter stuck in the tire comes out, the damaged part is sealed with the adhesive layer. However, this type only delays the decrease in the internal pressure of the damaged tire, and when the tire internal pressure becomes zero during parking, the subsequent driving (so-called run-flat driving) cannot be performed. Therefore, spare tires are indispensable for subsequent running, and replacement work on the spot is necessary. In addition, the adhesive layer near the foreign matter may be cured by heat aging, and the sealing ability is not reliable, so the practicality is not sufficient. Furthermore, when the vehicle is stopped for a long time with the tire temperature increased due to long-distance driving, the adhesive layer is fluidized due to the increased fluidity of the adhesive layer, which may cause uneven distribution on the tire inner surface. is there. In this case, the weight balance of the tire is lost, causing not only unpleasant vibrations, but also impairing the steering stability.

The second is a puncture repair agent. It consists of an electric pump that feeds adhesive seal liquid and compressed air, and repairs tires after being injured. In this case, when the pressure of the tire chamber becomes zero during parking, and when the fact is noticed, the above-described repair enables the subsequent traveling. However, in order to repair, you must choose a safe place, especially on icy and snowy road surfaces in winter and in insecure urban areas. It should be avoided as much as possible, and it can be said to be used only in the event of a puncture trouble in a safe parking lot.
On the other hand, if the pressure in the tire chamber gradually escapes from the damaged part while driving, unless the driver notices that abnormality, it is impossible to know when the tire chamber pressure will be zero and the vehicle will be unable to run. Since it will drive, it will continue to be a very dangerous driving situation, which is not a sufficient technique for safety.

  Further, a tire in which an internal cavity of an assembly of a tire and a rim to be attached to the tire is filled with a foam having closed cells is described in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4, for example. Yes. The tires proposed in these are mainly limited to special or small tires such as agricultural tires, rally tires, motorcycle tires and bicycle tires. Therefore, the application to tires such as tires for passenger cars, tires for trucks and buses, etc. that have high traveling speed, can withstand long-term use, and particularly place great importance on rolling resistance and riding comfort has been unknown. And since any foam has a low expansion ratio, the weight of the foam having bubbles is large, and it is inevitable that the vibration riding comfort and fuel consumption deteriorate, and the inside of the closed cells is atmospheric pressure. It has not been functionally sufficient to replace high-pressure air in conventional tires.

  Furthermore, Patent Document 5 discloses a puncture tire in which a foam filler is inserted into the inner periphery, but in addition to the disadvantage that the bubble internal pressure is very close to atmospheric pressure, the foam is a urethane-based material. Therefore, the energy loss resulting from the intermolecular hydrogen bond 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 generates heat due to repeated deformation at the time of rolling of the tire, and the durability is significantly lowered. In addition, since a material that is difficult to form bubbles independently is used, it is difficult to hold the gas because the bubbles easily communicate with each other.

  Furthermore, Patent Document 6 discloses an expansion pressure bubble body in which the outer periphery of a multi-bubble body mainly composed of closed cells is integrally encapsulated with an outer covering film having a thickness of 0.5 to 3 mm such as rubber or synthetic resin. A puncture tire has been proposed in which a large number are filled in a tire and the tire is maintained at a specified internal pressure. In this technology, in order to make the bubble internal pressure of the foam higher than the normal pressure, the amount of foaming agent contained in the closed cell forming raw material that becomes the expansion pressure foam is at least equal to or larger than the tire internal volume. It is set to the blending amount of the foaming agent that generates gas, and this aims at at least the same performance as a normal pneumatic tire.

  In the above technique, in order to prevent the dissipation of the gas in the bubbles in the expansion pressure bubble body, it is encapsulated and sealed integrally with an outer envelope film, but what is exemplified as the material of this outer envelope film is an automobile tube or Only materials such as the tube forming formulation. That is, envelop sealing is performed with a soft elastic envelope film mainly composed of butyl rubber having low nitrogen gas permeability used for tire tubes and 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 envelope film, an unvulcanized closed cell forming raw material is used as an expansion pressure foam, and a large number of these are placed inside a tire and rim assembly. Foam-filled tires are obtained by foaming by heating. Normal pressure air inside the tire due to the expansion of the foam is naturally exhausted from an exhaust hole formed in the rim.

  Here, since the internal pressure of the tire for passenger cars is generally set to about 150 to 250 kPa at room temperature, in order to produce the above foam-filled tire, the vulcanization molding is heated (about 140 ° C.). In the state, it is estimated from the gas state equation that the absolute pressure is about 1.5 times the internal pressure. However, at such a pressure level, it cannot be avoided that a blown occurs due to insufficient vulcanization pressure. In order to avoid this blown phenomenon, it is necessary to greatly increase the blending amount of the blowing agent in order to increase the pressure during vulcanization, or to increase the heating temperature to promote the crosslinking reaction.

  However, the method of increasing the blending amount of the foaming agent has been difficult to replace the conventional pneumatic tire because the internal pressure at room temperature greatly exceeds 300 kPa due to the increase in the blending amount of the foaming agent. Further, the method of increasing the heating temperature causes a problem in durability during long-term use because damage to the tire due to thermal aging is increased and the durability of the tire is greatly deteriorated. On the other hand, inside the tire and rim assembly, a large number of expansion pressure bubbles wrapped in a soft elastic envelope film are arranged. The friction between the soft elastic envelope films generated by the blown, the tire inner surface and the rim Problems with durability, such as friction with the inner surface, are significant. From the above, it can be said that the above-mentioned problem is a major drawback resulting from the arrangement of a large number of divided expansion pressure bubbles, unlike the shape of the expansion pressure bubbles having an integral donut shape. In addition, although the exhaust small hole opened in the rim is effective for naturally exhausting normal pressure air inside the tire due to the expansion of the expansion pressure bubble body, the exhaust gas bubble in the expansion pressure bubble body turn into. Therefore, the pressure in the expanded pressure bubble cannot be maintained for a long period of time and cannot be used for a long period of time.

  In addition, as a soft elastic envelope film, a composition mainly composed of butyl rubber, such as a tire tube, that has a low nitrogen gas permeability is used. But butyl rubber completes the reaction because the vulcanization reaction rate is extremely slow. For this purpose, a large heating time is required at a temperature of about 140 ° C. This means that the crosslink density of the soft elastic envelope film is insufficient, and it goes without saying that the soft elastic envelope film is peeled off. Further, the extension of the heating time further increases the damage to the tire due to the above-mentioned heat aging, and therefore a decrease in durability is unavoidable and cannot be said to be a good measure.

Patent Document 7 discloses an invention in which hollow spheres containing gas are arranged in a tire, and a puncture damage part is sealed to delay leakage of internal pressure. In the present invention, a large number of hollow particles obtained by heating and expanding expandable resin particles using liquefied gas as an expanding material are disposed in the tire. However, since the pressure of the hollow part after heating and expansion is determined by the ambient temperature and the vapor pressure of the gas, when placed in the tire and filled with air up to a predetermined internal pressure, the hollow part pressure is low and the hollow particles are spherical Can not be maintained, it will be present in the tire in the form of a crushed rugby ball. Such a crushed shape is not preferable when sealing a damaged part at the time of puncture. When the tire is injured under a low internal pressure of about 50 kpa, the hollow particles maintain a substantially spherical shape, and therefore a damaged portion by a nail of about 2.5 mmφ can be sealed. However, if the tire is damaged under an internal pressure as high as about 200 kpa required for regular running, the damaged portion by the 2.5 mmφ nail cannot be sealed, and hollow particles will be ejected. Moreover, since the average diameter of the foreign material stabbed into a tire is about 3.5 mmphi from the puncture actual condition survey in the present market, the said technique is inadequate. Furthermore, when the tire internal pressure was 200 kpa and the hollow particles were taken out after regular running of 1000 km, most of the particles were destroyed, and almost spherical particles were hardly seen. Further, the tire after running for 1000 km was damaged by nail penetration of 2.5 mmφ under 200 kpa, but the damaged part could not be sealed, and crushed hollow particles spouted out. From the above, simply disposing the hollow particles in the tire is not a sufficient technique because the damaged part cannot be sealed accurately and is destroyed in regular running.
JP-A-6-127207 JP-A-6-183226, JP-A-7-186610 JP-A-8-332805 Japanese Patent No. 2987076 JP-A-48-47002 JP 51-126604 A

  Accordingly, the present invention provides a tire and rim assembly that safely and reliably realizes a minimum movement from a punctured state after a tire has been damaged to a place where the tire can be repaired, for example. The purpose is to do.

  In addition, another object of the present invention is to provide durability and riding comfort in normal running before tire damage, fuel saving, versatility, and low running cost at a low cost without sacrificing productivity. Provided is a tire and rim assembly and a hollow particle group disposed inside the tire and rim assembly, which can guarantee and provide the tire and rim assembly with performance capable of withstanding regular driving at a higher speed. There is.

  As a result of intensive studies to solve the above-mentioned problems, the inventors appropriately give the minimum pressure in the tire chamber necessary for the subsequent driving when the gas in the tire chamber leaks due to trauma. In addition to recovering the pressure lost due to this, it has been found that it is necessary and effective to significantly improve the heat resistance and durability of the hollow particles under normal running, and the present invention has been completed.

That is, the gist configuration of the present invention is as follows.
(1) A tire and rim assembly in which a tire is mounted on a rim, and a large number of hollow particles composed of a continuous phase and closed cells are arranged in a tire chamber defined by the tire and the rim. The hollow particles are obtained by heating and expanding the expandable resin particles, and the expansion start temperature at which the expandable resin particles are heated and expanded is higher than the reexpansion start temperature at which reexpansion is started by reheating. An assembly of a tire and a rim having a hollow portion pressure of 70% or more of a vehicle-designated tire internal pressure during use and having a re-expansion start temperature in a range of 110 ° C to 200 ° C when heated.

(2) above (1) to Oite, assembly of the tire and rim re-expansion starting temperature of 130 ° C. or more hollow particles.

( 3 ) The tire / rim assembly according to (1) or (2 ) above, wherein the re-expansion start temperature of the hollow particles is 160 ° C. or higher.

( 4 ) The tire / rim assembly according to any one of the above (1) to ( 3 ), wherein the filling ratio of the hollow particles according to the following formula (I) is 5 vol% or more and 80 vol% or less.
Filling rate of hollow particles = (particle volume value / tire chamber volume value) × 100 --- (I)
here,
Particle volume value: The total volume (cm ³ ) of the total volume of all the hollow particles arranged in the tire chamber under atmospheric pressure and the void volume around the particles
Tire chamber volume value: After filling the tire / rim assembly with only air and adjusting it to the working internal pressure (kPa), the filled air discharge volume (cm) when the filled air is discharged until the internal pressure becomes atmospheric pressure ³ ) using the following formula (II) (cm
³ )
Tire chamber volume value = (filled air discharge) / (internal pressure / atmospheric pressure) --- (II)
In formula (II), the gauge pressure value (kPa) is used for the internal pressure, and the absolute value (kPa) measured by a barometer is used for the atmospheric pressure value.

( 5 ) The tire and rim according to any one of the above (1) to ( 4 ), wherein the gas inside the hollow particles before being arranged in the tire is different from the gas filled in the tire chamber. And assembly.

( 6 ) In the above ( 5 ), the gas inside the hollow particles before being placed in the tire is a non-flammable gas, and the gas inside the hollow particles in the assembly of the tire and the rim after applying the internal pressure is An assembly of a tire and a rim, which is a mixture of a nonflammable gas and a gas filled in a tire chamber.

( 7 ) In the above ( 5 ) or ( 6 ), the nonflammable gas is a linear or branched aliphatic hydrocarbon having 2 to 8 carbon atoms and a fluorinated product thereof, or an alicyclic having 2 to 8 carbon atoms. Hydrocarbons and their fluorinated products, and the following general formula (III):
R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) An assembly of a tire and a rim, which is at least one gas selected from the group consisting of ether compounds represented by:

( 8 ) The tire / rim assembly according to any one of the above ( 1 ) to ( 7 ), wherein the continuous phase of the resin constituting the shell of the hollow particles is an acrylonitrile resin.

( 9 ) In the above ( 8 ), the acrylonitrile-based resin is a terpolymer composed of acrylonitrile, methacrylonitrile, methyl methacrylate, or a terpolymer composed of acrylonitrile, methacrylonitrile, methacrylic acid. Tire and rim assembly.

( 10 ) The tire / rim assembly according to any one of the above (1) to ( 9 ), wherein the hollow part pressure of the hollow particles is equal to or higher than the vehicle-designated tire internal pressure during normal use.

( 11 ) The tire / rim assembly according to any one of ( 4 ) to ( 10 ), wherein a filling ratio of the hollow particles is 70 vol% or less.

( 12 ) The tire / rim assembly according to any one of the above ( 4 ) to ( 11 ), wherein a filling ratio of the hollow particles is 60 vol% or less.

( 13 ) The tire / rim assembly according to any one of ( 4 ) to ( 12 ), wherein a filling ratio of the hollow particles is 50 vol% or less.

( 14 ) In any one of the above (1) to ( 13 ), the average particle size of the hollow particle group disposed in the tire chamber is in the range of 40 to 200 μm, and the average true specific gravity of the hollow particle group is 0. A tire and rim assembly characterized by being in the range of 01 to 0.06 g / cm ³ .

( 15 ) In any of the above (1) to ( 14 ), the tire chamber pressure drop alarm function based on wheel speed detection by the wheel speed sensor of the anti-lock brake system and the direct measurement of the tire chamber pressure by the pressure sensor A tire and rim assembly characterized by having one or both of tire chamber pressure drop warning functions based on the system.

( 16 ) In any one of the above (1) to ( 15 ), a large number of foams having an average bulk specific gravity under an atmospheric pressure larger than the average true specific gravity of the hollow particles are further added to the tire chamber. An assembly of tires and rims, characterized in that they are arranged together.

( 17 ) In the above ( 16 ), the foam has a substantially spherical shape with a diameter of 1 to 15 mm or a cubic shape with a side of 1 to 15 mm, and an average bulk specific gravity of 0.06 to 0.3 (g / cc). A tire and rim assembly characterized in that it has closed cells or open cells.

(18) The hollow particle group according to any one of (1) to (17), wherein the following resin (A), the following thermally decomposable foaming agent (B), and the following foaming agent (C) The expandable resin particles containing any one or both of these are hollow particles obtained by heating and expanding to a temperature equal to or higher than the expansion start temperature for making hollow particles, and the expansion start temperature was obtained. higher than the re-expansion starting temperature when heated hollow particles again, and the in the range re-expansion starting temperature of 110 ° C. to 200 DEG ° C., the pressure in the hollow portion is 70% or more of the vehicle specified tire inflation pressure during regular travel use A group of hollow particles arranged inside a tire and rim assembly, characterized in that
(A) at least one selected from acrylonitrile polymers, acrylic polymers and vinylidene chloride polymers (B) dinitrosopentamethylenetetramine, azodicarbonamide, paratoluenesulfonylhydrazine and derivatives thereof, and oxybisbenzene At least one (C) straight chain and branched aliphatic hydrocarbon having 2 to 8 carbon atoms and fluorinated product thereof selected from sulfonylhydrazine, alicyclic hydrocarbon having 2 to 8 carbon atoms and fluorinated product thereof, And the following general formula (III): R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) At least one selected from ether compounds represented by

  Here, the pressure of the tire chamber described in the text indicates a gauge pressure (pressure indicated on the gauge) unless otherwise specified.

  According to the present invention, a function capable of stably traveling the required distance even when the tire chamber pressure is reduced after the tire is damaged is expressed, and the vehicle travels under a wider traveling speed condition from a low speed to a high speed under normal traveling. In this case, it is possible to provide an assembly of a tire and a rim that reliably holds the above function.

  The above effect can be obtained by arranging hollow particles having an expansion start temperature range defined by the present invention in the tire chamber, so there is no need to regulate the tire structure itself, and a general-purpose tire and a general-purpose rim can be provided. It can be used to provide a new safety tire / rim assembly.

Hereinafter, an assembly of a tire and a rim according to the present invention will be described with reference to FIG.
That is, the illustrated tire and rim assembly includes a tire 1 mounted on a rim 2 and a tire chamber 3 defined by the tire 1 and the rim 2 and is composed of a continuous phase made of resin and closed cells. A large number of substantially spherical hollow particles 4 are arranged. The tire 1 is not particularly limited in structure as long as it is a pneumatic tire according to the general standards such as various tires for automobiles, tires for trucks and buses, for example, tires for passenger cars. That is, the present invention is a technique that can be applied to all pneumatic tire and rim assemblies. For example, the illustrated tire is a general tire for an automobile, and is formed by arranging a belt 7 and a tread 8 sequentially in the radial direction outside at a crown portion of a carcass 6 extending in a toroidal shape between a pair of bead cores 5.
In the figure, reference numeral 9 denotes an inner liner layer, reference numeral 10 denotes a void around the hollow particle 4, and reference numeral 11 denotes a side portion.

  The hollow particles 4 have closed cells surrounded by a continuous phase of a substantially spherical resin, for example, a hollow body having a particle size distribution in the range of about 10 μm to 500 μm, or a small chamber of closed cells. It is a spongy structure including many. That is, the hollow particle 4 is a particle that encloses closed closed cells that do not communicate with the outside, and the number of closed cells may be singular or plural. In the present invention, the “inside closed cells of the hollow particle group” is collectively referred to as “hollow part”. In addition, the fact that the particles have closed cells means that the particles have a “resin shell” for enclosing the closed cells in a sealed state. Furthermore, the continuous phase by the above-mentioned resin refers to this “continuous phase on the component composition constituting the resin shell”. The composition of the resin shell is as described later.

  The hollow particle group, which is a large number of the hollow particles 4, is disposed inside the tire chamber 3 together with the high-pressure gas, so that it partially bears the “internal pressure” of the tire under normal use conditions and is damaged by the tire. Sometimes, it becomes a source for expressing the function of restoring the pressure lost in the tire chamber 3. This “internal pressure restoration function” will be described later. Here, “internal pressure” refers to “a tire chamber pressure value (gauge pressure value) for each mounting position specified by an automobile manufacturer for each vehicle”.

  Now, when a conventional pneumatic tire is run with the tire chamber pressure lowered to atmospheric pressure, the tire will be greatly bent by the load, and its side part will come into contact with the road surface, so friction with the road surface and repeated bending Due to the heat generated by the deformation, the carcass material of the skeleton is fatigued, and the abrasion damage on the side part finally penetrates into the tire chamber, leading to destruction.

  Therefore, the main object of the present invention is to properly apply the minimum tire chamber pressure necessary for the subsequent travel and recover the lost pressure when gas in the tire chamber leaks due to trauma. . Therefore, in the present invention, the tire and rim assembly is regarded as a pressure vessel. That is, the purpose of this object is to recover the pressure lost by functioning the hollow particles after temporarily sealing the wound of the pressure vessel damaged by the puncture with the hollow particle group arranged in the tire chamber. Is to achieve. Therefore, like the conventional pneumatic tire described above, the running after puncture should not lead to failure of the tire, that is, the pressure vessel.

  That is, even if the pressure of the tire chamber is reduced to atmospheric pressure, it is important to prevent the tire from being destroyed and to function as a pressure vessel by demonstrating the above functions at an early stage. In addition, it is important to restore the pressure in the tire chamber to “at least the pressure at which the side portion of the tire does not touch the ground”.

More specifically, with respect to the hollow particles disposed in the tire chamber, the filling ratio of the hollow particles according to the following formula (I) is preferably 5 vol% or more and 80 vol% or less.
Filling ratio of hollow particles = (particle volume value / tire chamber volume value) × 100 --- (I)

Here, the particle volume value is a total amount (cm ³ ) of the total volume of all the hollow particles arranged in the tire chamber under the atmospheric pressure and the void volume around the particles, and can be calculated by the following method.
First, the average bulk specific gravity of the particles under atmospheric pressure is determined. The method is calculated, for example, by measuring the weight of a known volume under atmospheric pressure. First, weigh the particles in a graduated cylinder under atmospheric pressure, apply vibration in an ultrasonic water bath, and stabilize the packing between the particles, and the total volume of the particles (including void volume around the particles) The average bulk specific gravity under the atmospheric pressure is calculated by measuring the total weight of the particles. That is, the average bulk specific gravity of the particles under atmospheric pressure is
Average bulk specific gravity of particles under atmospheric pressure = (total weight of particles) / (total volume of particles)
It is.
Next, by measuring the total weight of the particles arranged in the tire chamber and dividing by the average bulk specific gravity of the particles calculated above under atmospheric pressure, the “particle volume” arranged inside the tire is calculated. be able to. That is,
Particle volume = (total weight of particles filled in tire) / (average bulk specific gravity of particles under atmospheric pressure)
It is.
In addition, particles having a desired particle volume can be arranged in the tire by a method of measuring particles in a container having a known volume and arranging the particles in the tire chamber.

The tire chamber volume value is adjusted to the working internal pressure (kPa) by filling the tire and rim assembly with only air, and then the filled air is discharged when the filled air is discharged to the atmospheric pressure. It is a value (cm ³ ) obtained from the following formula (II) using the amount (cm ³ ).
Tire chamber volume value = (filled air discharge) / (internal pressure / atmospheric pressure) --- (II)
In equation (II), the gauge pressure value (kPa) is used for the internal pressure, and the absolute value (kPa) measured by a barometer is used for the atmospheric pressure value. That is, the atmospheric pressure is represented by 0 [kPa] in terms of the gauge pressure, but the atmospheric pressure value itself changes every day, so the absolute value observed from the barometer at that time is used. Therefore, for example, when the atmospheric pressure at a certain time is 1013 hPa, 101.3 kPa is used as the absolute value of atmospheric pressure in the formula (II).

Hereinafter, the reason why the filling rate of the hollow particles described above is 5 vol% or more and 80 vol% or less will be described in order from the normal use to the puncture state.
First, a case where a large number of hollow particles are arranged in a tire chamber and the tire chamber is filled with a high-pressure gas to set the tire chamber pressure to the use internal pressure will be described.
In the present invention, after the hollow particles 4 are arranged in the tire chamber 3, the pressure around the voids 10 around the particles 4, in other words, the pressure in the tire chamber becomes a desired use internal pressure such as a mounting vehicle designated internal pressure, It is important to fill with high-pressure gas such as air or nitrogen.
When the hollow particles 4 are arranged in the tire chamber 3 and further filled with gas to set the pressure of the tire chamber 3 to a desired pressure, the pressure in the hollow portion of the hollow particles (pressure in closed cells) is initially set to the tire. The particles are reduced in volume because they are smaller than the pressure in the air chamber. The shape of the hollow particles at this point is not a substantially spherical shape, but is a flattened shape distorted from a spherical shape. When the tire travel is started in a state where the particle shape is flattened and distorted, the hollow particles are more likely to be broken due to collision between the particles and collision with the tire and the inner surface of the rim than in the spherical shape. That is, when the hollow particles are flattened and distorted, the input due to the collision cannot be uniformly dispersed, resulting in a great disadvantage in terms of durability.

  On the other hand, flattened and distorted hollow particles are in a state of volume reduction due to the difference between the pressure in the hollow portion and the pressure in the tire chamber, but the pressure in the tire chamber (the void around the particles) over a certain period of time. By continuing to maintain the pressure, the pressure in the hollow part of the hollow particle, in other words, the pressure in the closed cell in the particle can be increased to the pressure of the tire chamber. That is, since the flattened hollow particles are deformed, a force for returning to the original substantially spherical shape acts on the shell portion. In addition, since the pressure in the hollow portion of the flattened hollow particles is lower than the pressure in the tire chamber, gas molecules in the tire chamber pass through the shell of the continuous phase made of resin in order to eliminate the pressure difference. And penetrates into the hollow part of the particle. Furthermore, since the hollow part of a hollow particle is a closed cell and the gas in it is satisfy | filled with the gas resulting from a foaming agent, it may differ from the gas of a tire air chamber (gap part surrounding particle | grains). In this case, not only the above-described pressure difference but also the gas partial pressure difference, the high-pressure gas in the tire chamber penetrates into the particle hollow portion until the partial pressure difference is eliminated. Thus, since the high pressure gas in the tire chamber penetrates into the hollow portion of the hollow particles with time, the pressure in the tire chamber is reduced by the amount permeated into the hollow portion. Therefore, the tire of the present invention adjusted to the desired use internal pressure can be obtained by continuously applying the desired pressure after filling the high-pressure gas in order to compensate for the permeation into the hollow part of the hollow particles.

  Thus, while the pressure inside the hollow part of the hollow particle approaches the pressure of the tire chamber (the void around the particle), the particle volume once reduced is recovered, and the particle shape is flattened and distorted It will recover to its original spherical shape. In the process of recovering this shape, the pressure in the hollow portion of the hollow particle increases to at least 70% of the pressure in the tire chamber, so that the particle shape recovers from a flattened state to a substantially spherical shape. This can guarantee the durability of the particles described above.

  According to the above method, high-pressure gas is interposed around the hollow particles, so that the load borne by the hollow particles during normal travel can be reduced to a negligible level, and the hollow particles recovered from the above-described particle volume can be reduced. In the particles, since the particle shape is restored to a substantially spherical shape, fatigue and breakage applied to the particles along with repeated deformation during rolling of the tire can be greatly reduced, so that the durability of the particles is not impaired. The range in which the durability of the hollow particles is not impaired is the process in which the pressure in the hollow portion of the particle increases while the pressure in the tire chamber recovers the volume in the desired high-pressure environment such as the vehicle specified internal pressure In this case, the pressure of the hollow part of the hollow particles is preferably at least 70% with respect to the desired pressure in the tire chamber. Furthermore, it is recommended to set a high value of 80% or more, 90% or more, and 100% or more.

  Here, in order to obtain a tire-rim assembly in which the pressure in the hollow portion of the hollow particles is at least 70% of the pressure in the desired tire chamber, at least the pressure of the void gas around the hollow particles is mounted. What is necessary is just to hold | maintain to the state raised to 70% or more with respect to the pressure in desired tire air chambers, such as a vehicle designated internal pressure, and to pass appropriate time, continuing applying this pressure. Alternatively, the hollow particles are placed in a pressure vessel separate from the tire, and the void pressure around the particles is maintained at least 70% higher than the pressure in the desired tire chamber, and this pressure is continuously applied. The desired tire and rim can also be obtained by storing the particles in the hollow portion of the hollow particles in the tire chamber together with the surrounding atmosphere after storing the pressure vessel in the pressure vessel for an appropriate time. And an assembly can be obtained.

  The appropriate holding time described above is set in consideration of the permeability of the void gas to the hollow particle shell portion, that is, the continuous phase of the particle, and the partial pressure difference between the gas in the particle hollow portion and the void gas. Good.

By selecting and adjusting the type and pressure of the gas that fills the tire chamber (the void around the particle) according to the mechanism, particle shape, and volume change process described above, the inside of the hollow portion of the hollow particle Can be set within a desired range.

As described above, the pressure in the tire chamber is increased by disposing particles in the tire chamber whose pressure in the hollow part of the hollow particles is at least 70% of the pressure in the desired tire chamber. It is necessary to realize that the pressure of the tire chamber is restored to at least the tire chamber pressure at which the side portion of the tire does not come into contact with the ground when traveling from a pressure state.
The mechanism for restoring the tire internal pressure will be described below.

  Now, in the tire and rim assembly in which the above-described hollow particle group is arranged in the tire chamber, when the tire is damaged, the high-pressure gas in the tire chamber existing in the gap 10 between the hollow particles 4 is removed. As a result of leaking to the outside of the tire, the pressure in the tire chamber drops to a pressure comparable to atmospheric pressure. In the course of the tire chamber pressure drop, the following occurs in the tire chamber.

First, when the tire is damaged and the pressure in the tire chamber begins to decrease, many of the hollow particles seal the damaged portion and suppress a rapid decrease in the air chamber pressure. Here, in the present invention, the hollow part pressure of the hollow particles is specified to be at least 70% of the vehicle designated tire internal pressure during normal running use, but the sealing ability of the damaged part depends on the hollow part pressure. That is, although it has been described above that a substantially spherical shape can be maintained if the hollow portion pressure is 70% or more, since good fluidity and elasticity can be expressed by maintaining the substantially spherical shape, the hollow portion internal pressure is low. Compared to the above, the sealing limit of the damaged part is greatly improved.
On the other hand, as the air chamber pressure decreases, the amount of tire deflection increases and the tire air chamber volume decreases. Further, when the air chamber pressure is lowered, the tire is greatly bent, and the hollow particles arranged in the tire air chamber are subjected to compression and shear inputs while being sandwiched between the tire inner surface and the rim inner surface.

In addition , the pressure in the hollow portion of the hollow particles that existed under the above-described internal pressure (bubble internal pressure in the closed cell) remains high after the scratch in accordance with the above-mentioned internal pressure. It exists in the tire chamber while maintaining the previous particle volume and hollow part pressure. Therefore, when the tire further rolls, the hollow particles themselves bear a load while the hollow particles cause friction and self-heat, so that the temperature of the hollow particles in the tire chamber rises rapidly. When the temperature exceeds the re- expansion start temperature of the hollow particles (Ts2: corresponding to the glass transition temperature of the resin), the shell of the particles starts to soften. At this time, since the pressure in the hollow part of the hollow particle is a high pressure corresponding to the working internal pressure, and the hollow part pressure is further increased due to a sudden rise in the temperature of the hollow particle, the hollow particle expands at a stretch and the particle Since the surrounding void gas is compressed, the pressure of the tire chamber can be recovered to at least the tire chamber pressure at which the side portion of the tire does not come into contact with the ground.

If the pressure in the hollow part of the hollow particles is set to a high pressure that enables thermal expansion by the above mechanism, the function of restoring the internal pressure can be exhibited.
That is, in order to restore the pressure in the tire chamber to the tire internal pressure at which the side portion does not contact the ground, the hollow particles whose pressure in the hollow portion is at least 70% of the use internal pressure are filled with 5 vol% or more and 80 vol% or less. It is important to place it in the tire chamber at a reasonable rate. The reason is shown below.
When the filling rate of the hollow particles is less than 5 vol%, the damaged portion can be sealed without any problem. However, since the absolute amount of the hollow particles is insufficient, the side portion is sufficiently restored to a pressure level that does not contact the ground. It becomes difficult to obtain internal pressure. On the other hand, when the filling ratio of the hollow particles exceeds 80 vol%, some tires expand due to heat generation due to particle friction during high-speed running during normal use, resulting in expansion exceeding the expansion start temperature (Ts2) of the hollow particles described above. The internal pressure restoration function, which is the main function of the present invention, may be lost. The heat generation of particles during high-speed running during normal use will be described later.

  Further, in order to reliably develop the above-described internal pressure recovery function, it is important to securely seal the damaged portion before the internal pressure recovery function is expressed. In other words, if sealing of the damaged part is incomplete, the pressure that should have been recovered leaks from the damaged part, so that the pressure obtained by the internal pressure recovery function can only temporarily contribute to the subsequent running ability. In addition, there is a risk that the running performance after the injury cannot be guaranteed. Since the hollow particles are particles having a low specific gravity and elasticity due to the hollow structure, when the tire is damaged and the void gas around the hollow particles starts to leak from the damaged portion, the hollow particles get on the flow due to the leakage of the void gas. Immediately close to the wounded part and instantly seal the wound at the wounded part. As described above, the function of sealing the damaged part by the hollow particles is an essential function that supports the function of restoring the internal pressure of the present invention.

  As described above, in the tire-rim assembly filled with particles according to the present invention, the friction between the hollow particles is reduced due to the decrease in the tire chamber volume and the increase in the amount of deflection of the tire due to the decrease in the internal pressure after puncture. By causing this, the temperature rises rapidly and the internal pressure is restored due to the expansion of the particles, and safe driving after puncture can be realized.

  By the way, the friction between the hollow particles in the tire and rim assembly is generated although it is minute even under normal traveling. However, in the region where the traveling speed is 100 km / h or less, the generated frictional heat itself is small, and the balance is maintained by heat radiation to the outside air by traveling.

However, in a high speed region exceeding 150 km / h, and in an extremely hot environment where the temperature environment of the outside air is remarkably high, the heat generation to the outside air is insufficient while the generated frictional heat increases, and the temperature environment of the hollow particles May be significantly worse. If such a situation continues for a long time, the temperature of the hollow particles exceeds the re- expansion start temperature (Ts2), so that the particles expand. As a result, the above-mentioned “internal pressure restoration function is lost during puncture”. Sometimes.

The inventors have intensively studied to solve this problem, and prevent the loss of the internal pressure restoration function due to the heat generation of the hollow particles in high-speed running, and new hollow particles that enable regular running at higher speeds. I came to find out.
That is, the tire generates centrifugal force corresponding to the speed by rotating at a high speed. The hollow particles arranged in the tire chamber are also subjected to the same centrifugal force. This centrifugal force is proportional to the weight of the particles and proportional to the square of the speed, and inversely proportional to the tire radius. Furthermore, a certain amount of bending is caused by applying a load to the tire, and the grounding area is in a state parallel to the road surface. Is almost zero. Therefore, the hollow particles in the assembly of the tire and the rim that rotate while bearing a load are subjected to the centrifugal force as described above in the non-grounded region, while the centrifugal force is released immediately after entering the grounded region. It is placed “under repeated input of centrifugal force”.

Therefore, it is preferable to suppress the particle weight as much as possible for the hollow particle group arranged in the air chamber of the tire. That is, the average true specific gravity of the hollow particles is preferably selected as small as possible, and the filling ratio of the hollow particles with respect to the volume of the tire chamber is set to a sufficient internal pressure up to the pressure level at which the side portion is not grounded. It is preferable to select a filling rate that is as small as possible within the range of “a filling rate that exhibits a resurrection function”.
When the filling ratio of the hollow particles is less than 5 vol%, it is difficult to obtain a sufficient rejuvenation internal pressure up to a pressure level at which the side portion does not come into contact with some tires. On the other hand, if the filling rate of the hollow particles exceeds 80 vol%, depending on the tire, heat generation due to particle friction at high speed during normal use causes expansion beyond the re- expansion start temperature of the hollow particles described above. Since the internal pressure restoration function which is the main function of the invention may be lost, it is not preferable. Therefore, the preferable range of the hollow particle filling rate is 5 vol% or more and 80 vol% or less, and further 70 vol% or less, 60 vol% or less, and 50 vol% or less.

  The average true specific gravity of the hollow particles is preferably in the range of 0.01 to 0.06 g / cc. That is, if it is less than 0.01 g / cc, the durability of the hollow particles under normal running is lowered, and the aforementioned “internal pressure restoration function” may be lost during normal use. On the other hand, if it exceeds 0.06 g / cc, the centrifugal force fluctuation input in the above-mentioned regular high-speed running becomes large and the heat generation amount becomes large, which is not preferable.

  Here, the hollow particle group arranged in the tire chamber has a distribution in the true specific gravity, and each hollow particle does not have the same true specific gravity value. The reason for this is the non-uniformity of the thermal history during heating and expansion and the retention of the expanding gas caused by the foaming agent. In the process where each expandable resin particle, which is the raw material of the hollow particles, expands into a hollow particle by heating, if the heat history during heating is uneven, the hollow expanded sufficiently by receiving the heat history The particles and the hollow particles that have stopped expanding in the middle due to little thermal history received will coexist. In the “expandable resin particles”, those having a small particle size are relatively thin in the continuous phase, which is the shell of the particles (referring to the skin enclosing the foaming agent), and those having a large particle size are those of the shell. Thick. Even if the heat history at the time of heating is the same, the retention of the expanded gas generated by heating in the hollow particles depends on the absolute thickness of the shell. Therefore, the “expandable resin particles” having a small particle size before expansion become hollow particles having a low expansion coefficient and a low expansion coefficient because the shell is thin, and the true specific gravity is large. Conversely, “expandable resin particles” with a large particle size become hollow particles with high retention of expansion gas and high expansion coefficient due to the thick shell, and can grow to a larger particle size, resulting in a lower true specific gravity. . That is, hollow particles obtained by expansion of an expandable composition such as a microcapsule generally have a distribution in particle size in the expanded state, and the hollow particles having a smaller particle size are more true. A hollow particle having a larger specific gravity and a larger particle size has a smaller true specific gravity.

  Therefore, fully expanded hollow particles have a small true specific gravity, and conversely, hollow particles that have stopped expanding in the middle are components having a large true specific gravity. When a particle group having such a true specific gravity distribution is arranged in the tire, a centrifugal force corresponding to the speed is received under traveling at normal internal pressure. At this time, particles having a large true specific gravity are subjected to a greater centrifugal force in the tire chamber than particles having a small true specific gravity. Therefore, a particle group having a small true specific gravity exists in the vicinity of the inner surface of the wheel in the tire and rim assembly, and a hollow particle group having a large true specific gravity gradually exists as the distance from the center of rotation increases. Then, particles having the largest true specific gravity exist on the inner liner surface side under the tread, and the particle groups move from the wheel inner surface side toward the inner liner surface side under the tread (outward in the tire rotation radius direction). ) It reaches the slope with true specific gravity.

  Here, while the tire is placed in the above-mentioned “under repeated fluctuation input”, the hollow particle group having a large true specific gravity is larger than the hollow particle group having a small true specific gravity with a large inertia under the fluctuation input in the ground contact region. Generate power. Therefore, since the hollow particle group having a large true specific gravity moves around to separate the coexisting “hollow particle group having a smaller true specific gravity”, the difference in relative inertia force between the small true specific gravity particle and the large true specific gravity particle The difference in kinetic energy due to the above causes generation of excess inter-particle frictional heat, resulting in a deterioration in the exothermic property of the entire particle. That is, the heat generation factor of the hollow particles is the relative inertia force difference of the large true specific gravity particle group with respect to the small true specific gravity particles and the frictional heat generation due to the motion thereof.

  Therefore, in order to suppress the frictional heat generation, first, as a means for reducing the above-described relative inertial force difference, it is possible to narrow the true specific gravity distribution width of the hollow particles. For example, by removing only the same volume ratio from the large true specific gravity side (small particle size side) and the small true specific gravity side (large particle size side) for hollow particles having a certain average true specific gravity, the average true specific gravity does not change. In both cases, since the true specific gravity distribution width can be narrowed, the above-described difference in relative inertial force can be suppressed, and the heat generation of the entire hollow particle group can be suppressed.

  Second, by removing only the large specific gravity particle group (small particle size side) that is the heat source directly, narrowing the true specific gravity distribution and reducing the average true specific gravity, the relative inertia force difference In addition, by suppressing the inertial force level itself, heat generation of the entire hollow particle group can be further suppressed.

  Here, with respect to the average particle size of the hollow particles, a preferable range is from 40 μm to 200 μm. When the average particle size of the hollow particles is less than 40 μm, the above-described true specific gravity distribution spreads, and the exothermic properties deteriorate due to the relative inertia force difference of the large true specific gravity particle group with respect to the small true specific gravity particle group and the frictional heat generated by the motion. Therefore, it is not preferable. On the other hand, if the average particle size of the hollow particles exceeds 200 μm, the hollow particles may be used in the situation where the particles collide with each other under normal running or when the pressure in the tire chamber becomes atmospheric due to puncture. In a situation where the group directly supports the load, the particles on the large particle size side are selectively broken, which may be disadvantageous in that it may not be possible to obtain the desired post-puncture running performance.

As mentioned above, for the problem of heat generation of hollow particles, which is a concern in high-speed driving during normal use and in extreme heat, focus on the particle weight, the average true specific gravity of the hollow particles, and the true specific gravity distribution width of the hollow particles. The improved means was mentioned. Although certain effects can be obtained by these means, further heat resistance and durability of the hollow particles are required in view of the recent progress in performance and speedup of vehicles.
Therefore, the inventors have intensively studied the actual state of heat generation of the hollow particles, and achieved further improvement in heat resistance and durability of the hollow particles. Now, the hollow particles are obtained by heating and expanding the “expandable resin particles” as the raw material, and the expandable resin particles have an expansion start temperature Ts1. Further, when the hollow particles obtained by the thermal expansion are heated again, the hollow particles start to expand further, and there exists a reexpansion start temperature Ts2 of the hollow particles. The inventors have produced hollow particles from a large number of expandable resin particles, and as a result of repeated studies, Ts1 has been used as an index of heat durability, but Ts2 is appropriate as an index of heat durability. I came to find out.

First, the expansion behavior was observed when the expandable resin particles were heated and expanded. Since the expandable resin particles are in a stage before expansion, the particle diameter is extremely small as compared with the state of the hollow particles, and the thickness of the resin shell is extremely thick. Therefore, the microcapsule has a high rigidity. Therefore, even if the continuous phase of the resin shell exceeds the glass transition point in the process of thermal expansion, the expansion force of the internal gas overcomes the rigidity of the shell until the shell is softened to some extent by further heating. I can't. Therefore, Ts1 shows a higher value than the actual glass point transfer of the shell.
On the other hand, when the hollow particles are heated and expanded again, the thickness of the shell of the hollow particles is extremely thin and the rigidity as the hollow body is low. Therefore, since the continuous phase of the shell exceeds the glass transition point in the process of thermal expansion, expansion starts at the same time, so Ts2 is positioned lower than Ts1.

In the present invention, since the expansion characteristics of the hollow particles once expanded are utilized instead of utilizing the expansion characteristics of the expandable resin particles, the conventional Ts1 is used to discuss the heat durability. However, Ts2 should be used as an index.
Further, it is important that Ts2 of the hollow particles is 110 ° C. or higher and 200 ° C. or lower. This is because if Ts2 of the hollow particles is less than 110 ° C., depending on the selected tire size, the hollow particles may start to re-inflate before reaching the guaranteed speed of the tire.
On the other hand, if the temperature exceeds 200 ° C., the re-expansion start temperature Ts2 may not be reached even in the run flat running after the puncture damage even if the temperature rises due to the frictional heat generation of the hollow particles. In some cases, the “internal pressure restoration function” cannot be fully developed.

Accordingly, the scope of the Ts2 is at 200 ° C. or less 110 ° C. or more, preferably 130 ° C. or more, more preferably 0.99 ° C. or higher, most preferably in the range of the 160 ° C. or more.

  As described above, by arranging the hollow particles having the re-expansion start temperature Ts2 in accordance with the upper limit value and the lower limit value described above, the heat pressure durability is improved in high speed running as well as ensuring the function of restoring the internal pressure. By doing so, “internal pressure restoration function retention” during regular running is achieved.

Next, as the gas constituting the hollow part (closed cell) of the hollow particle, nitrogen, air, linear and branched aliphatic hydrocarbons having 2 to 8 carbon atoms and fluorinated products thereof, carbon numbers 2 to 8 are used. And fluorinated products thereof, and the following general formula (III):
R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) And at least one selected from the group consisting of ether compounds. The gas filled into the tire chamber may be air. However, when the gas in the particles is not a fluorinated product, a gas not containing oxygen, such as nitrogen or an inert gas, is preferable from the viewpoint of safety.

  The method of obtaining hollow particles having closed cells is not particularly limited, but a method of obtaining “expandable resin particles” using a foaming agent and heating and expanding the particles is common. Examples of the foaming agent include a method utilizing vapor pressure such as high-pressure compressed gas and liquefied gas, and a method utilizing a thermally decomposable foaming agent that generates gas by thermal decomposition. In particular, many thermally decomposable foaming agents are characterized by generating nitrogen, and the particles obtained by appropriately controlling the reaction of the expandable resin particles obtained by foaming by these have mainly nitrogen in the bubbles. It will be a thing. Although it does not specifically limit as this thermally decomposable foaming agent, Dinitroso pentamethylenetetramine, azodicarbonamide, para-toluene sulfonyl hydrazine and its derivative (s), and oxybisbenzene sulfonyl hydrazine can be mentioned suitably.

A method for obtaining “expandable resin particles” that become hollow particles by utilizing vapor pressures of high-pressure compressed gas and liquefied gas will be described below.
When polymerizing the continuous phase of the resin forming the particles, linear and branched aliphatic hydrocarbons having 2 to 8 carbon atoms and their fluorinated products, alicyclic hydrocarbons having 2 to 8 carbon atoms and their fluoro And the following general formula (III):
R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) In this method, at least one selected from the group consisting of ether compounds represented by the following formula is liquefied under high pressure as a blowing agent and dispersed in a reaction solvent, followed by emulsion polymerization. This makes it possible to obtain a "expandable resin particles" as containment in the previous mentioned resin continuous phase of the gas components shown above as a blowing agent in a liquid state, by which heat expand it, the desired hollow particles I can get it.

  Further, the surface of the “expandable resin particles” is coated with an anti-blocking agent such as silica particles, carbon black fine powder, antistatic agent, surfactant, oil agent, etc. Can be obtained.

  In addition, in order to apply the minimum required internal pressure by the hollow particles in a state where the tire chamber pressure is reduced due to damage, the gas sealed at a predetermined pressure in the hollow portion of the particles should not leak out of the particles. In other words, it is important that the continuous phase of the resin corresponding to the shell part of the hollow particles has a property that gas is difficult to permeate. That is, the resin constituting the continuous phase is made of a material having low gas permeability, specifically, it is made of at least one of acrylonitrile copolymer, acrylic copolymer, and vinylidene chloride copolymer. Is essential. These materials are particularly effective in the present invention because they have flexibility as hollow particles with respect to input due to tire deformation.

  In particular, it is preferable to apply any one of an acrylonitrile polymer, an acrylic polymer, and a vinylidene chloride polymer to the continuous phase of the hollow particles. More specifically, the monomer constituting the polymer is a polymer selected from acrylonitrile, methacrylonitrile, methyl methacrylate, methacrylic acid, and vinylidene chloride, preferably acrylonitrile / methacrylonitrile / methyl methacrylate terpolymer, acrylonitrile. At least one selected from the group consisting of / methacrylonitrile / methacrylic acid terpolymer is advantageously suitable. Since all of these materials have a small gas permeability coefficient and are difficult for gas to permeate, the gas in the hollow part of the hollow particles hardly leaks to the outside, and the pressure in the hollow part can be appropriately maintained.

Further, the continuous phase of the hollow particles has a gas permeability coefficient at 30 ° C. of 300 × 10 ⁻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, it is recommended and further preferably the gas permeability coefficient at 30 ° C. is ^{2 × 10 -12 (cc · cm} / cm 2 · s · cmHg) or less. This is because the gas permeability coefficient of the inner liner layer in a normal pneumatic tire is at a level of 300 × 10 ⁻¹² (cc · cm / cm ² · s · cmHg) or less and has a sufficient internal pressure holding function. In view of the above, the gas permeation coefficient at 30 ° C. was set to 300 × 10 ⁻¹² (cc · cm / cm ² · s · cmHg) or less for the continuous phase of the particles. However, at this gas permeation coefficient level, it is necessary to replenish the internal pressure once every 3 to 6 months. From the standpoint of maintainability, 20 × 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.

  Here, in arranging the hollow particles in the tire chamber according to the present invention, in order to enhance the sealing function of the tire damage part when the tire is damaged, the foam having an average bulk specific gravity larger than the average true specific gravity of the hollow particles Means for mixing a large number of bodies in the hollow particle group is effective. Specifically, it has a substantially spherical shape with a diameter of 1 to 15 mm or a cubic shape with a side of 1 to 15 mm, has independent or open cells, has an average bulk specific gravity of 0.06 to 0.3 g / cc, and particles By adding a large number of foams having a bulk specific gravity value larger than the average true specific gravity, it is possible to extend the expression period of the internal pressure restoration function and increase the running ability after tire damage.

  That is, since the hollow particles have a substantially spherical shape, the fluidity is high, so that the hollow particles can be easily arranged from the inlet having a small inner diameter such as a tire valve into the tire chamber. On the other hand, when the tire is damaged, the hollow particles gather from the damaged portion inside the damaged portion in an attempt to blow out with the high-pressure gas in the tire chamber from the damaged portion to the outside of the tire. However, since the wound path from the inner surface of the scratched part to the outer peripheral surface of the tire is not a straight line but presents a complicated and complicated shape, the particles entering from the wound on the inner surface of the tire are obstructed on the way of the path, resulting in a large number of hollow particles. Will gather in a compressed state on the inner surface of the damaged part, and the damaged part is temporarily sealed. Here, provisionally sealing refers to a state in which the hollow particles themselves do not leak, but the void gas around the particles gradually leaks.

  At that time, depending on the shape and size of the wound at the wounded part, provisional sealing with only particles may be incomplete. In such a case, the level of sealing can be improved as follows by adding a large number of the foams described above.

  That is, a centrifugal force corresponding to the speed is generated in the tire chamber during rolling, and under the centrifugal force, the foam having a large bulk specific gravity moves toward the inner liner side of the tire and the small specific gravity is small. The hollow particles are unevenly distributed to the side closer to the rotation center than the foam. In this state, even if the particles are damaged so as not to be sealed only by the particles, the foam is unevenly distributed near the inner liner surface of the tire inner surface. It is extremely effective to seal the wounded part by quickly coming into close contact with the inner surface of the wounded part of the wounded part in order to blow out to the outside.

  In particular, when the foam is a foam made of thermoplastic urethane having open cells, it is highly compressible and easily adheres to the shape of the wound, and as a result, a large wound can be made extremely complicated and fine by the foam. This makes it possible to change the dissipated flow path of the complicated and refined gas to a state most suitable for sealing with the hollow particles, which is a very effective means.

Incidentally, in the tire and rim assembly of the present invention, the tire chamber pressure drop alarm function based on the wheel speed detection by the wheel speed sensor of the anti-lock brake system and the direct measurement method of the tire chamber pressure by the pressure sensor are provided. It is preferable to provide one or both of the tire chamber pressure drop warning functions. FIG. 2 shows an example of a structure for mounting the seed sensor 12 on the tire.
In other words, in the present invention, when the vehicle travels while the pressure in the tire chamber is reduced due to puncture, the internal pressure is restored by the above-described mechanism, so that the driver may not be aware of tire damage depending on the situation. However, since the tire itself is damaged by punctures, it is very dangerous that the tire may break down if it continues to run. Therefore, it is preferable to use the above-mentioned tire internal pressure drop warning function together.

Further, it is preferable to have a tire valve used in combination with hollow particles and gas filling. The tire valve includes a filter that blocks hollow particles in the tire chamber and allows only gas to pass outside the tire chamber. By attaching such a tire valve, when manufacturing the tire and rim assembly of the present invention, it is possible to place hollow particles in the tire chamber with only one valve. A general-purpose rim having only holes can be used as it is. In addition, it is possible to prevent “leakage of hollow particles in the gas replenishing operation” against the natural drop of the tire chamber pressure during normal running, and to easily maintain the tire chamber pressure.
As such a tire valve, one having the structure illustrated in FIG. 3 can be used. Here, the code | symbol 13 is the said filter, For example, a nonwoven fabric can be used.

  A rim having the size shown in Table 1 was incorporated into a tire having the size shown in Table 1 that satisfies the general structure shown in FIG. 1, and an assembly of a tire for a passenger car and a rim was prepared. Next, after selecting a target vehicle for each tire size and mounting a load equivalent to four passengers, the high pressure air is filled and the pressure of the tire chamber is adjusted to 200 kPa. The assembly was mounted on the left side of the front shaft. Here, the tire chamber pressure was gradually released while keeping the load applied, and the tire chamber pressure value at which the side portion of the tire contacted the road surface or the inner liner inner surfaces contacted each other was obtained. This tire chamber pressure value was defined as "RF running limit internal pressure value".

Next, the air chamber pressure of each tire is adjusted to 200 kPa which is a working internal pressure under a state where no load is applied, and high pressure air in the air chamber is discharged to obtain a gas discharge amount. Volume was calculated. The calculation results are shown in Table 1.
Here, the air volume of the assembly of the tire and the rim was measured according to the following procedure.
[Measurement method of tire chamber volume]
Step 1: while maintaining the state in which that no load is the assembly of the tire and rim, filled with air at room temperature, a predetermined pressure (using pressure) is adjusted to P _2. In this case, the tire's air chamber volume of interest in P ₂ under and V _2.
Procedure 2: The tire valve is opened, and the air in the tire chamber is discharged to the atmospheric pressure P ₁ while flowing into the integrating flow meter, and the charged air discharge amount V ₁ is measured. As the integrating flow meter, DC DRY gas meter DC-2C, intelligent counter SSF manufactured by Shinagawa Seiki Co., Ltd. was used.
Using the above measured values,
Tire chamber volume value = (filled air discharge) / (internal pressure / atmospheric pressure) --- (II)
Accordingly, the tire chamber volume V ₂ at the use internal pressure P ₂ can be obtained.
In the formula (II), the internal pressure used was a gauge pressure value (kPa), and the atmospheric pressure value was an absolute value (kPa) measured by a barometer.

Moreover, the pressure in the hollow part of the hollow particle arrange | positioned in the tire air chamber shown in Table 1 was measured as follows.
[How to check the pressure level in the hollow part]
Place the hollow particles in the tire chamber and kept a certain period to a desired use internal pressure P _2, to prepare the tire of interest. By disposing a filter in the valve, when the valve is opened, the hollow particles stay in the tire chamber and only a high-pressure gas is discharged. Then, once the pressure of the tire chamber to atmospheric pressure, and adjusted to the pressure P _50% corresponding to 50% P ₂ in terms of gas-filled again, large air in the room air tire by opening the tire valve While discharging it to the atmospheric pressure P ₁ , it is passed through the integrating flow meter, and the air discharge amount V _50% is measured. And the void volume value V (cm ³ ) around the particle under the following formula P _50% =
[Air discharge value V _50% (cm ³ )] / [Internal pressure value P _50% (kPa) / Atmospheric pressure P ₁ (kPa)]
Thus, the void volume value V around the particle at the pressure P _50% is obtained. Similarly, the void volume around the particles at each pressure level such as P _30%, P _70%, P _80%, P _90%, etc. is calculated. If the pressure in the hollow portion is less than the pressure in the tire chamber, the volume of the hollow particles is reduced and the void volume around the particles is increased accordingly. Therefore, the above measurement was started from a sufficiently low pressure level, and the pressure level at which the void volume around the particle began to increase was defined as the pressure level in the hollow part of the hollow particle.

  Further, hollow particles having various specifications were applied as shown in Table 1 to the tire chambers of the tire and rim assembly, and the tire and rim assembly shown in Table 1 was obtained. Here, the tire 1 conforms to a general structure of the tire type and size.

  In Table 1, the types of compositions constituting the continuous phase of the hollow particles are as shown in Table 2. The expandable resin particles shown in Table 2 were heated and expanded to form hollow particles, and the average particle diameter and average true specific gravity of the obtained particle group were measured. The hollow particles shown in Table 3 were arranged in each tire chamber under the filling rate shown in Table 1.

In addition, the measuring method of the average true specific gravity of a hollow particle is as follows.
[Measurement method of average true specific gravity]
The average true specific gravity value of the particles is generally measured by a liquid replacement method (Archimedes method), which is an ordinary method using isopropanol, and this ordinary method is also used in the present invention.

Moreover, the measuring method of the average particle diameter and particle size distribution of a hollow particle is as follows.
Instrument: Sympatec Gmbh Laser Diffraction Particle Size Analyzer HELOS & RODOS System Measurement conditions: 2S-100ms / DRY
Dispersion pressure: 2.00 bar, feed: 50.00%, rotation: 60.00%
Shape factor: 1.00
Measurement is performed under the above conditions, and the following measured values are adopted.
That is, the volume-based average particle size is set as the average particle size value (D50 value) of the present invention.

Furthermore, the measuring method of the thermal expansion start temperature Ts1 of each expandable resin particle and the reexpansion start temperature Ts2 of each hollow particle is as follows.
[Rise Zhang start temperature measurement method of particle]
The thermal expansion start temperature Ts1 and the re-expansion start temperature Ts2 in Table 2 were measured for the expansion displacement amount under the following conditions, and were defined as temperatures at the time when the displacement amount rose.
Equipment: PERKIN-ELMER 7Series
“Thermal Analysis System”
Measurement conditions: temperature rising rate 10 ° C./min, measurement start temperature 25 ° C., measurement end temperature 220 ° C.
Measurement physical quantity: Measures the amount of expansion displacement due to heating.

  Next, the assembly of the passenger car tire and the rim was filled with air or nitrogen, and adjusted to 200 kPa, which was the working internal pressure. Then, after investigating the particle volume recovery behavior based on the investigation method shown below in advance, the retention time corresponding to the target pressure in the hollow part is determined, and the tire chamber pressure is maintained in a heated room maintained at room temperature or 45 ° C. Thus, the assembly of the tire and the rim to be evaluated was prepared while increasing the hollow portion pressure of the hollow particles and recovering the particle volume.

Here, a method of finding an appropriate holding time for increasing the pressure in the hollow part of the hollow particles is as follows.
First, a transparent acrylic pressure-resistant container made of an acrylic resin having an inner volume of about 1000 cm ^{3 and a} constant inner cross-sectional diameter is prepared, and the hollow particles of the present invention are placed in the container while vibrating the container with an ultrasonic water bath or the like. Filled until full. Next, this container was filled with a gas filling the tire chamber until a desired working pressure such as a vehicle designated internal pressure was reached. Since the volume of the particles in the container decreases as the pressure increases, the height inside the container of the portion filled with the hollow particles (hereinafter referred to as the hollow particle height) decreases. When the internal pressure of the container reached the target pressure, the container was vibrated for 5 minutes with an ultrasonic water bath or the like and then allowed to stand for 5 minutes. And when the hollow particle height in a container was stabilized, hollow particle height was measured and it was set as "the hollow particle height at the time of a pressurization start: H1." Further, the above-mentioned working pressure was continuously applied, and “height of hollow particles after a certain period of time: Hx” was measured.

Next, record the change over time while measuring the hollow particle height at regular intervals while applying the above pressure, and continue the measurement until the hollow particle height does not change. Hollow particle height: H2 ”was measured. From the above, the particle volume recovery rate was calculated by the following formula.
That is,
Particle volume recovery rate (%) = [[Hx−H1] / [H2−H1]] × 100
Based on the above measurement results, the time to reach the target volume recovery rate is determined, and the tire and rim assembly in which the hollow particles are arranged is filled with a gas having a desired pressure, and the above is determined. The pressure in the hollow part of the hollow particles was increased by performing a recovery treatment of the total particle volume according to the holding time.

First, a high-speed heating drum test was performed using the obtained tire and rim assembly.
That is, the evaluation assembly adjusted to each internal pressure value is attached to a drum testing machine set to a test environment temperature of 38 ° C., and running at a speed of 100 km / h is started while applying the load shown in Table 1. The speed was increased by 10 km / h every minute, and changes in the particle temperature in the tire chamber and the pressure in the tire chamber were measured. In addition, a pressure sensor that monitors the tire chamber pressure is arranged on the inner surface of the rim to be evaluated, and a thermocouple that measures the temperature of the hollow particles is arranged in the center of the inner liner inner surface in the tire width direction. The temperature data signal was transmitted by radio waves using a commonly used telemeter, and changes in the tire chamber pressure and the hollow particle temperature were measured while being received by a receiver installed in the test chamber.

  In this test, the speed obtained by adding 10 km / h to the guaranteed speed according to the speed symbol of each tire was evaluated as the “upper speed”. That is, when the temperature of the hollow particles reached Ts2, which is the re-expansion start temperature of the hollow particles, before reaching the above upper limit speed, the traveling was stopped up to the speed at that time. In addition, when the temperature of the hollow particles did not reach Ts2, which is the re-expansion start temperature of the hollow particles even under the upper limit speed, traveling was stopped up to the upper limit speed. A case where the speed at the time when the travel stop was determined was equal to or higher than the guaranteed speed according to the speed symbol of each tire was determined to be acceptable.

In addition, the air pressure of the assembly of each of the other evaluation tires and rims was adjusted to each internal pressure value, and the drum traveling over a distance of 50000 km was performed at a speed of 90 km / h while applying the load shown in Table 1. Added history by.
Then, after setting a passenger car of a class corresponding to each size tire to a loading capacity equivalent to four passengers, the evaluation tire was attached to the left front wheel, and the axle weight of the left front wheel of this vehicle was measured. Next, four nails having a diameter of 5.0 mm and a length of 50 mm were stepped out from the tread surface of the assembly toward the inside of the tire, and after confirming that the tire chamber pressure had dropped to atmospheric pressure, 90 km / h The circumference of the test course was run flat at a speed of, the particle temperature in the tire chamber and the chamber pressure were continuously measured, and the occurrence of the internal pressure restoration function was investigated.

In addition, on the inner surface of the rim of the assembly of the tire and rim to be evaluated, a pressure sensor that monitors the tire chamber pressure is incorporated, and the signal of the measured pressure data is transmitted by radio using a commonly used telemeter, While measuring the change in pressure by receiving with a receiver installed inside the test vehicle, the vehicle traveled up to 100 km. The internal pressure recovery function under run-flat driving against the above-mentioned “RF driving limit internal pressure value”, which is “the tire chamber pressure value where the tire side is in contact with the road surface or the inner liner inner surfaces contact each other” A case where the pressure value in the tire chamber due to the expression was superior was judged to be acceptable.
These survey results are also shown in Table 1.

1 is a tire width direction sectional view showing an assembly of a tire and a rim according to the present invention. It is a tire width direction sectional view showing an example of an assembly of a tire and a rim according to the present invention carrying a tire air chamber pressure drop alarm device. It is a figure which shows an example of the "valve for tires provided with the filter" used together with the filling of a hollow particle and gas mounted in the assembly of the tire and rim | limb according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 2 Rim 3 Tire air chamber 4 Hollow particle 5 Bead core 6 Carcass 7 Belt 8 Tread 9 Inner liner layer 10 Space | gap around particle | grains 11 Side part 12 Sensor 13 Filter

Claims (18)

A tire and rim assembly in which a tire is mounted on a rim, and a plurality of hollow particles composed of a continuous phase and closed cells made of a resin are disposed in a tire chamber defined by the tire and the rim. The hollow particles are obtained by heating and expanding the expandable resin particles, and the expansion start temperature at which the expandable resin particles are heated and expanded is higher than the reexpansion start temperature at which the reexpansion is started by reheating . An assembly of a tire and a rim having a hollow portion pressure of 70% or more of a vehicle-designated tire internal pressure and having a re-expansion start temperature in a range of 110 ° C to 200 ° C when heated.   The tire / rim assembly according to claim 1, wherein the re-expansion start temperature of the hollow particles is 130 ° C or higher.   The tire / rim assembly according to claim 1 or 2, wherein the re-expansion start temperature of the hollow particles is 160 ° C or higher. 4. The tire / rim assembly according to claim 1, wherein the filling ratio of the hollow particles according to the following formula (I) is 5 vol% or more and 80 vol% or less.
Filling rate of hollow particles = (particle volume value / tire chamber volume value) × 100 --- (I)
here,
Particle volume value: Total volume of all hollow particles placed in the tire chamber under atmospheric pressure and the total volume of voids around the particles (cm ³ )
Tire chamber volume value: After filling the tire and rim assembly with only air and adjusting it to in-use (kPa), the amount of air discharged when the internal air is discharged until the internal pressure reaches atmospheric pressure (cm ³ ), the value obtained from the following formula (II) (cm ³ )
Tire chamber volume value = (filled air discharge) / (internal pressure / atmospheric pressure) --- (II)
In formula (II), the gauge pressure value (kPa) is used for the internal pressure, and the absolute value (kPa) measured by a barometer is used for the atmospheric pressure value.   5. The tire / rim assembly according to claim 1, wherein the gas inside the hollow particles before being disposed in the tire is a gas different from the gas filled in the tire chamber.   In Claim 5, the gas inside the hollow particles before being placed in the tire is a nonflammable gas, and the gas inside the hollow particles in the assembly of the tire and the rim after applying the internal pressure is the nonflammable gas. An assembly of a tire and a rim, which is a mixture with a gas filled in a tire chamber. 7. The nonflammable gas according to claim 5, wherein the nonflammable gas is a linear or branched aliphatic hydrocarbon having 2 to 8 carbon atoms and a fluorinated product thereof, an alicyclic hydrocarbon having 2 to 8 carbon atoms or a fluorinated product thereof. And the following general formula (III):
R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) An assembly of a tire and a rim, which is at least one gas selected from the group consisting of ether compounds represented by:   8. The tire / rim assembly according to claim 1, wherein the continuous phase of the resin constituting the shell of the hollow particle is an acrylonitrile resin.   9. The tire and rim according to claim 8, wherein the acrylonitrile-based resin is a terpolymer composed of acrylonitrile, methacrylonitrile, or methyl methacrylate, or a terpolymer composed of acrylonitrile, methacrylonitrile, or methacrylic acid. And assembly.   The tire and rim assembly according to any one of claims 1 to 9, wherein the hollow part pressure of the hollow particles is equal to or higher than a vehicle-designated tire internal pressure during normal running use.   11. The tire and rim assembly according to claim 4, wherein a filling ratio of the hollow particles is 70 vol% or less.   The tire / rim assembly according to any one of claims 4 to 11, wherein a filling ratio of the hollow particles is 60 vol% or less.   The tire / rim assembly according to any one of claims 4 to 12, wherein a filling ratio of the hollow particles is 50 vol% or less. The hollow particle group disposed in the tire chamber has an average particle diameter in the range of 40 to 200 µm and the hollow particle group has an average true specific gravity of 0.01 to 0.06 g / A tire and rim assembly, characterized in that it is in the range of cm ³ .   15. The tire chamber according to claim 1, further comprising a tire chamber pressure drop alarm function based on wheel speed detection by a wheel speed sensor of an anti-lock brake system and a direct measurement method of tire chamber pressure using a pressure sensor. A tire and rim assembly characterized by providing either or both of a pressure drop alarm function.   In any one of Claims 1 thru | or 15, many of the foam whose average bulk specific gravity under atmospheric pressure is larger than the average true specific gravity of this hollow particle was mixed and arrange | positioned in this hollow particle group in the tire chamber. A tire and rim assembly characterized by the above.   The foam according to claim 16, wherein the foam has a substantially spherical shape with a diameter of 1 to 15 mm or a cubic shape with a side of 1 to 15 mm, and an average bulk specific gravity of 0.06 to 0.3 (g / cc). A tire and rim assembly characterized by having closed cells or open cells. It is a hollow particle group in any one of Claims 1 thru | or 17, Comprising: One or both of the following resin (A), the following thermally decomposable foaming agent (B), and the following foaming agent (C). Is a hollow particle obtained by heating and expanding to a temperature equal to or higher than the expansion start temperature for making the hollow particle, and the expansion start temperature is obtained by heating the obtained hollow particle again. higher than the re-expansion starting temperature of the case, and the in the range re-expansion starting temperature of 110 ° C. to 200 DEG ° C., the pressure in the hollow portion is 70% or more of the pressure of the vehicle specified tire inflation pressure during regular travel use A hollow particle group disposed inside an assembly of a tire and a rim.
(A) at least one selected from acrylonitrile polymers, acrylic polymers and vinylidene chloride polymers (B) dinitrosopentamethylenetetramine, azodicarbonamide, paratoluenesulfonylhydrazine and derivatives thereof, and oxybisbenzene At least one (C) straight chain and branched aliphatic hydrocarbon having 2 to 8 carbon atoms and fluorinated product thereof selected from sulfonylhydrazine, alicyclic hydrocarbon having 2 to 8 carbon atoms and fluorinated product thereof, And the following general formula (III): R ¹ —O—R ² ---- (III)
(Wherein R ¹ and R ² are each independently a monovalent hydrocarbon group having 1 to 5 carbon atoms, and part of the hydrogen atoms of the hydrocarbon group may be replaced by fluorine atoms) At least one selected from ether compounds represented by

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