JP2004130831A - Tubeless tire - Google Patents

Abstract

An object of the present invention is to develop a tubeless tire which is excellent in gas barrier properties (air impermeability) and in which a gas barrier layer is firmly laminated as a coating film on the inner surface of a tire body.
In a tubeless tire in which a tire main body mounted on an outer periphery of a rim directly forms an air chamber between an inner surface thereof and a rim, an inner surface of the tire main body has a particle diameter of 5 μm or less, A gas barrier layer composed of a gas barrier resin composition containing an inorganic layered compound having a ratio of 200 to 3000 and a high hydrogen bonding resin is laminated as a coating film.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tubeless tire that can maintain air pressure stably for a long period of time.
[0002]
[Prior art]
Tubeless tires, in which the tire body attached to the outer periphery of the rim directly forms an annular air chamber between the inner surface and the rim, do not require rubber tubes or the like, and are easy to handle. Widely used and well known as tires for motorcycles and the like.
[0003]
However, since the tire body is usually made of a rubber-based material and generally has some degree of air permeability, the air in the tire supplied to a predetermined pressure in advance gradually leaks over time and the air pressure gradually decreases. Therefore, troublesome maintenance work such as periodically inspecting the tires and refilling the air was required.
[0004]
In order to solve such a problem, for example, an air-impermeable layer made of an ethylene / vinyl alcohol copolymer formed in a film shape is bonded to and integrated with an inner surface of the tire body directly or via an adhesive resin layer. A tubeless tire has been proposed (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-2000-177307 (page 2)
[0006]
[Problems to be solved by the invention]
However, such an air-impermeable layer made of an ethylene / vinyl alcohol copolymer does not yet have a sufficient gas barrier property, and the retention time of the set air pressure is not always satisfactory. The film is bonded to the inner surface of the tire body that has been molded into a predetermined shape, or it is manufactured by laminating the film to the tire base material before molding and then shaping it into a tire shape, but in the case of the former method, Since the inner surface of the tire body is a concave shape having a narrow width, it is difficult to work to uniformly join the film to the inner surface, it is easy to cause uneven bonding and the like, and air leaks from the portion easily occur, and In the case of the latter method, since the surface of the tire base material and the film are surface-bonded, smoothness between the bonding surfaces is required, and if it is insufficient, peeling easily occurs. How there was a problem.
[0007]
The present invention has been made to solve such a problem, and is a tubeless tire having excellent gas barrier properties (air impermeability) and having a gas barrier layer firmly laminated as a coating film on the inner surface of a tire body. Is provided.
[0008]
[Means for Solving the Problems]
That is, the present invention provides a tubeless tire in which a tire body mounted on the outer periphery of a rim directly forms an air chamber between the inner surface and the rim, wherein the inner surface of the tire body has a particle size of 5 μm or less, An object of the present invention is to provide a tubeless tire in which a gas barrier layer comprising a gas barrier resin composition containing an inorganic layered compound having an aspect ratio of 200 to 3000 and a high hydrogen bonding resin is laminated as a coating film.
[0009]
Since the tubeless tire of the present invention having the above-mentioned configuration has a gas barrier layer composed of the gas barrier resin composition specified above, the gas barrier property itself is extremely excellent, and the gas barrier layer is laminated as a coating film. In addition, the gas barrier layer can be reliably provided on the inner surface of the tire body without any uneven bonding as in the case of laminating a film. Can be maintained.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[0011]
The basic structure of a tubeless tire used in conventionally known automobiles, motorcycles and the like is, for example, as shown in FIG. An air chamber 4 is directly formed between the rim 1 and the rim 1. An inner liner 5, which is often made of butyl rubber or the like, is provided on the inner surface of the tire main body.
[0012]
The tubeless tire of the present invention has a known structure as illustrated in FIG. 1 except that the gas barrier layer specified in the present invention is laminated as a coating film 6 on the inner surface of the tire main body as shown in FIG. This is basically the same as the tubeless tire described above, and the configuration of the tire main body is not particularly limited. Therefore, the inner liner illustrated in FIG. 1 is not necessarily required.
In the present invention, the inner surface of the tire main body refers to the inner surface of the tire main body which comes into contact with the air chamber when the tire main body is mounted on the outer periphery of the rim. When such layers are provided, it means the inner surface of the tire main body in contact with the air chamber 4 including these layers.
[0013]
In the tubeless tire of the present invention, a gas barrier layer comprising a gas barrier resin composition containing an inorganic layered compound having a particle diameter of 5 μm or less and an aspect ratio of 200 to 3000 and a high hydrogen bonding resin is provided on the inner surface of such a tire body. It is formed as a coating film.
[0014]
The high hydrogen bonding resin that forms the gas barrier resin composition is a resin having a hydrogen bonding group or an ionic group that is a crosslinkable functional group.
Here, the hydrogen-bonding group is a group capable of hydrogen bonding, and specific examples thereof include a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, and the like. It is a group capable of ionic bonding, and specific examples include a carboxylate group, a sulfonate ion group, a phosphate ion group, an ammonium group, and a phosphonium group. Among these hydrogen bonding groups and ionic groups, particularly preferred are a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, a carboxylate group, a sulfonic acid ion group, and an ammonium group.
[0015]
The content of the hydrogen-bonding group or the ionic group in the high hydrogen-bonding resin (when both are included, the total amount of both) is usually in the range of 20 wt% to 60 wt%, preferably 30 wt% to 60 wt%. It is within the range of 50 wt%. The contents of the hydrogen bonding group and the ionic group can be measured by nuclear magnetic resonance (for example, ¹ H-NMR, ¹³ C-NMR, and the like).
[0016]
Specific examples of such a high hydrogen bonding resin include polyvinyl alcohol (PVA) and its modified products, polysaccharides, ethylene / vinyl alcohol copolymer (EVOH) and its modified products, polyacrylic acid and its esters, Examples thereof include sodium polyacrylate, polystyrene sulfonic acid, sodium polystyrene sulfonate, polyethylene imine, polyallylamine and quaternary ammonium salts thereof, polyvinyl thiol, and polyglycerin.
[0017]
Examples of the PVA include a polymer obtained by hydrolyzing or transesterifying (saponifying) an acetate portion of a vinyl acetate polymer, a trifluorovinyl acetate polymer, a vinyl formate polymer, a vinyl pivalate polymer, Polymers obtained by saponifying a t-butyl vinyl ether polymer, a trimethylsilyl vinyl ether polymer, and the like are included.
Examples of the modified PVA include polyvinyl alcohol resins modified with at least one compound having a silyl group in the molecule described in JP-A-3-93542.
[0018]
The saponification rate of PVA is usually at least 70 mol%, preferably at least 85 mol%, more preferably at least 98 mol%, and most preferably a completely saponified product.
The degree of polymerization of PVA is preferably in the range of 100 to 20,000, and more preferably in the range of 200 to 5,000. Further, the above PVA may be modified with a small amount of a copolymer monomer.
[0019]
The polysaccharide is a polymer synthesized by polycondensation of various monosaccharides, and in the present invention, a polymer obtained by chemically modifying the polymer is also included. Examples of such polysaccharides include cellulose, cellulose derivatives (hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, etc.), amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan and the like.
[0020]
As the ethylene / vinyl alcohol copolymer (EVOH), those having a vinyl alcohol fraction in the range of 40 mol% to 80 mol% are preferable, and those having a vinyl alcohol fraction in the range of 45 mol% to 75 mol%. Is particularly preferred. The melt index (MI) of the EVOH is not particularly limited, but is preferably 0.1 g / 10 min to 50 g / 10 min under the conditions of a temperature of 190 ° C. and a load of 2.160 g. EVOH may be modified with a small amount of a comonomer.
[0021]
One kind of such a high hydrogen bonding resin may be used alone, or two or more kinds thereof may be used in combination. Among these resins, PVA and its modified products, polysaccharides, EVOH and its modified products are preferable, and PVA is most preferable.
[0022]
The high hydrogen bonding resin may be used alone, but as long as it does not affect the gas barrier properties, it may be used as a copolymer with another copolymerizable monomer, or may be mixed with another monomer. It can be used together with resin. Examples of the resin that can be used in combination include a polyester resin, a polyurethane resin, a polyamide resin, an epoxy resin, and a melamine resin.
[0023]
Further, a crosslinking agent capable of performing a crosslinking reaction with the high hydrogen bonding resin can be blended with the high hydrogen bonding resin. The amount of the crosslinking agent is not particularly limited, and an effective amount of the crosslinking agent may be used. As the above-mentioned cross-linking agent, an organometallic compound is particularly preferable since a cross-linking structure can be imparted to the high hydrogen bonding resin layer while maintaining flexibility. The organometallic compound used here is a compound capable of forming a coordination bond, a hydrogen bond, an ionic bond, and the like by a crosslinking reaction with a highly hydrogen-bonding resin.
[0024]
Preferable examples of the organometallic compound include various metal alkoxides, titanium organic compounds, zirconium organic compounds, aluminum organic compounds, and silicon organic compounds. Among the above organometallic compounds, a chelating compound, for example, an organometallic compound having a chelating ligand such as acetylacetonate and coordinating with a high hydrogen-bonding resin has a moderate crosslinking reactivity. Is preferred.
[0025]
A silane coupling agent is particularly preferably used as the silicon organic compound. As such a silane coupling agent, an organoalkoxysilane containing an organic reactive group, particularly an organoalkoxysilane having an epoxy group, is suitable. Specifically, there are, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Such a silane coupling agent may be used alone or in combination of two or more. It is also preferable to use the silane coupling agent in combination with a metal alkoxide.
[0026]
In addition, organic cross-linking such as aldehyde cross-linking agents such as formaldehyde, acetaldehyde, and gliogizar, epoxy cross-linking agents such as water-soluble polyfunctional epoxy, isocyanate cross-linking agents such as polyfunctional isocyanate compounds, and melamine cross-linking agents such as methylolated melamine. Agents are also suitably used.
[0027]
The method of crosslinking a high hydrogen bonding resin using a crosslinking agent is, for example, a method according to the method described in JP-A-8-99390, that is, the above-mentioned organometallic compound, high hydrogen bonding resin, sol-gel method. By mixing a catalyst, an acid, a solvent, and the like, a coating liquid to be a gas barrier layer B is prepared, applied to the base layer A, dried, and further subjected to a polycondensation reaction in the drying step. Effective crosslinking can be performed.
[0028]
Examples of the inorganic layered compound which is another essential component used together with the high hydrogen bonding resin in forming the gas barrier resin composition include various compounds described in JP-A-7-247374, such as graphite and phosphate. And the like. Derivative-based compounds (zirconium phosphate-based compounds), chalcogenides, clay-based minerals, hydrotahydrotalcite compounds, and the like, among which clay-based minerals are preferred.
The chalcogenide is a dichalcogenide of an element selected from Group IV (Ti, Zr, Hf), Group V (V, Nb, Ta) and Group VI (Mo, W) of the periodic table, formula: is a compound represented by MX _2. In the formula, M represents an element selected from the above groups IV to VI, and X represents chalcogen (S, Se, Te).
[0029]
Among the above clay minerals, smectite, vermiculite and mica clay minerals are preferable, and smectite group is particularly preferable. Preferred clay minerals of the smectite group include, for example, montmorillonite, beidellite, nontronite, saponite, sauconite, stevensite, hectorite, and those obtained by treating these clay minerals with organic substances (hereinafter sometimes referred to as organically modified clay minerals). ).
[0030]
The gas barrier resin composition applied to the present invention is usually prepared as a dispersion comprising the high hydrogen bonding resin, the inorganic layered compound and the dispersion medium described above. Those that swell and / or cleave in a medium are preferred. Specifically, those having a swelling value of 5 or more in the following swelling test are preferable, and those having a swelling value of 20 or more are more preferable. Further, those having a cleavage value of 5 or more in the following cleavage test are preferable, and those having a cleavage value of 20 or more are more preferable.
[0031]
(Swellability test)
100 ml of a solvent is placed in a 100 ml measuring cylinder, and 2 g of the inorganic stratiform compound is gradually added thereto. After standing at 23 ° C. for 24 hours, the volume (ml) of the inorganic layered compound dispersed layer is read from the scale of the interface between the inorganic layered compound dispersed layer and the supernatant in the measuring cylinder. The larger the value (swelling value), the higher the swelling property.
[0032]
[Cleavability test]
30 g of the inorganic layered compound is gradually added to 1,500 ml of a solvent, and a dispersing machine (despa MH-L, manufactured by Asada Iron Works Co., Ltd., blade diameter 52 mm, rotation speed 3,100 rpm, container capacity 3 L, distance between bottom and blade 28 mm) )), The mixture is dispersed at a peripheral speed of 8.5 m / min at 23 ° C. for 90 minutes, and 100 ml of the dispersion is collected in a measuring cylinder.
After standing for 60 minutes, the volume (ml) of the inorganic layered compound dispersed layer is read from the scale at the interface between the layered compound dispersed layer and the supernatant in the measuring cylinder. The larger the numerical value (cleavage value), the higher the cleavage property.
[0033]
As a dispersion medium for swelling and / or cleaving the inorganic layered compound, when the inorganic layered compound is a natural swellable clay mineral, water, alcohols (methanol, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, etc.), Examples thereof include dimethylformamide, dimethylsulfoxide, and acetone. Among them, water, alcohol, and a water-alcohol mixture are particularly preferable.
When the inorganic layered compound is an organically modified clay mineral, examples of the dispersion medium include aromatic hydrocarbons (such as benzene, toluene and xylene), ethers (such as ethyl ether and tetrahydrofuran), and ketones (such as acetone and acetone). Methyl ethyl ketone, methyl isobutyl ketone, etc.), aliphatic hydrocarbons (n-pentane, n-hexane, n-octane, etc.), halogenated hydrocarbons (chlorobenzene, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane, Perchlorethylene), ethyl acetate, methyl methacrylate (MMA), dioctyl phthalate (DOP), dimethylformamide, dimethyl sulfoxide, methyl cellosolve, silicone oil and the like.
[0034]
The average particle size of the inorganic layered compound is preferably 5 μm or less from the viewpoint of gas barrier properties, and its aspect ratio is preferably in the range of 200 to 3000.
If the average particle size exceeds 5 μm or the aspect ratio is less than 200, the gas barrier properties of the laminate are not sufficient, and it is difficult to obtain and manufacture an inorganic layered compound having an aspect ratio larger than 3000.
[0035]
Here, the particle diameter of the inorganic layered compound indicates a particle diameter (volume-based median diameter) obtained by a known method using a diffraction / scattering method in a dispersion medium. That is, the particle size is calculated from the diffraction / scattering pattern obtained when light is passed through the dispersion of the inorganic layered compound, by Mie scattering theory or the like, to calculate the particle size distribution that is most consistent with the diffraction / scattering pattern. Can be obtained by
When the inorganic layered compound is sufficiently swelled and cleaved with a dispersion medium of the same type as the dispersion medium used in the diffraction / scattering method, and is then composited with a resin, the swelling and swelling of the resulting resin composition is reduced. The particle size of the cleaved inorganic layered compound is substantially equal to the particle size of the swollen / cleaved inorganic layered compound in the dispersion medium.
[0036]
Further, the aspect ratio (Z) of the inorganic layered compound is a value obtained by using the formula: Z = L / a. Here, L indicates the average particle size of the inorganic layered compound obtained by the above-mentioned diffraction / scattering method, and a indicates the unit thickness of the inorganic layered compound, that is, the thickness of the unit crystal layer of the inorganic layered compound.
[0037]
The “unit thickness a” of the inorganic layered compound can be determined by a powder X-ray diffraction method (see “Guide to Instrumental Analysis (a)” (1985, published by Kagaku Dojinsha, supervised by Jiro Shiokawa), page 69). it can.
[0038]
The aspect ratio (Z) obtained as described above is not always exactly equal to the true aspect ratio of the inorganic layered compound in the gas barrier layer (coating film). It can be regarded as the aspect ratio of the inorganic layered compound therein.
[0039]
In the present invention, the “aspect ratio” of the inorganic layered compound means the “aspect ratio (Z)” defined above, and the “particle size” indicates “the particle size L obtained by a diffraction / scattering method”. Shall be.
[0040]
In the gas barrier resin composition applied to the present invention, the content of the inorganic layered compound is not particularly limited, but if the content is too small, the gas barrier performance is not sufficient, and if it is too large, the gas barrier layer (coating film) Is generally brittle, so that it is usually in the range of 3 to 70% by weight in the total amount of the inorganic layered compound and the high hydrogen bonding resin.
[0041]
In addition, in the gas barrier resin composition containing the inorganic layered compound and the high hydrogen bonding resin composition, unless particularly adversely affecting the tubeless tire, ultraviolet absorbers, coloring agents, antioxidants, surfactants and the like Various additives may be included. Examples of the surfactant include, but are not particularly limited to, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, and a nonionic surfactant.
[0042]
The tubeless tire of the present invention is obtained by laminating a gas barrier layer composed of the gas barrier resin composition as a coating film. The thickness of the coating film is usually 0.01 or more, preferably 0 from the viewpoint of gas barrier properties. .1 μm or more.
The upper limit is not particularly limited, and is arbitrarily set from the viewpoint of target gas barrier properties and economic efficiency.
[0043]
In addition, such a coating film may be composed of only one layer, or may have a multi-layered configuration as required.
[0044]
There is no particular limitation on the method of laminating a gas barrier layer comprising a bus barrier resin composition containing an inorganic layered compound and a high hydrogen bonding resin on the inner surface of the tire body as a coating film. To prepare a coating solution obtained by dissolving or dispersing the third component as described above in a solvent, if necessary, such that the coating solution has a desired thickness by a method such as spraying or brushing. A method of applying the coating liquid to the inner surface of a tire body shaped into a predetermined shape, and then removing the solvent, or applying the coating liquid to a tire base material before shaping the tire shape into a roll coater, a slit coater, and a bar. A method of applying by a usual coating method such as a coater, and then removing the solvent and then shaping into a tire shape.
In this case, the thickness of the coating film does not necessarily need to be uniform on the inner surface of the tire, and depending on the configuration of the tire, for example, the tread portion of the tire is relatively thin, and the side wall portion and the bead portion are appropriately changed such as increasing the thickness. Is also good.
[0045]
In the preparation of the coating liquid, the inorganic layered compound and the resin may be added separately to a solvent (dispersion medium) after being mixed or beforehand. For example, (1) dissolving the high hydrogen bonding resin in the solvent (2) adding the dispersion obtained by dispersing the inorganic layered compound to the high hydrogen bonding resin, and adding the resin to the dispersion. A method of dissolving, (3) a method of adding an inorganic layered compound to a solution obtained by dissolving a high hydrogen bonding resin in a solvent, and dispersing the inorganic layered compound in the above solution to form a dispersion liquid is suitably used. Can be
[0046]
As the solvent (dispersion medium) in this case, a dispersion medium used for swelling and / or cleaving the inorganic layered compound is exemplified, and water or an alcohol or a water-alcohol mixture is particularly preferably used. .
The amount of the dispersion medium used is appropriately determined depending on the type of the dispersion medium, coating conditions such as the coating method, and the desired thickness of the coating film, and is not particularly limited.
[0047]
In the preparation method of the coating liquid, it is preferable that the inorganic layered compound is dispersed as finely and uniformly as possible in the coating liquid, and a high-pressure dispersion treatment known as a dispersion method of adjusting the coating liquid as such a method is used. It is preferred to do so.
[0048]
In applying the coating liquid, a surface treatment such as an anchor treatment, a corona treatment, a flame plasma treatment, an ozone treatment, and an electron beam treatment is performed on the application surface in advance for the purpose of improving the adhesion (adhesion) to the application surface. It is effective to give it.
[0049]
For example, when an anchor layer is provided on the application surface as an anchor treatment, the material used as the anchor layer can improve the adhesiveness between the application surface to which the coating liquid is applied and the coating film that is the gas barrier layer. There is no particular limitation as long as it is present, and examples thereof include polyethyleneimine-based, alkyl titanate-based, polybutadiene-based, urethane-based, and ionomer-based. As a material for the anchor layer, a urethane-based material prepared from an isocyanate compound and an active hydrogen compound is preferable from the viewpoint of water resistance.
[0050]
As a method of such an anchor treatment, a conventionally known method applied when forming a gas barrier layer composed of a gas barrier resin composition containing an inorganic layered compound and a high hydrogen bonding resin is applied, and is not particularly limited.
The thickness of the anchor layer is also arbitrary, but is usually from 0.03 μm to 2.0 μm, preferably from 0.05 μm to 1.0 μm.
[0051]
The tubeless tire of the present invention, as described above, on the inner surface of the tire body, a gas barrier layer made of a bus barrier resin composition containing an inorganic layered compound and a high hydrogen bonding resin is laminated as a coating film, The coating film does not necessarily need to be on the outermost surface of the inner surface of the tire main body, and if necessary, a protective layer may be further provided on the surface of the laminated coating film.
As a result, it is possible to prevent the coating film from being damaged when the tire body is mounted on the outer periphery of the rim.
In this case, the protective layer does not necessarily need to be provided on the entire surface of the coating film formed of the gas barrier layer, and may be provided only on the inner surface of the outer peripheral portion of the tire to be mounted on the rim.
[0052]
The protective layer is not particularly limited as long as it has adhesiveness to the coating film and has a certain level of mechanical strength. In this case, a film-like material is applied since some uneven bonding is allowed. Although it may be combined, it is preferable that the coating film can be further coated on the coating film with a resin dispersion liquid or a resin solution like the above-mentioned coating film.
[0053]
【The invention's effect】
The tubeless tire of the present invention has excellent gas barrier properties itself, and furthermore, because the gas barrier layer is firmly laminated as a coating film, there is no uneven bonding as a layer, and a gas barrier layer is formed on the inner surface of the tire body. The tire can be reliably provided, and as a result, the air retention as a tire is remarkably excellent, and the air pressure can be stably maintained over a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a conventional tubeless tire mounted on a rim.
FIG. 2 is a cross-sectional view of a main part of the tubeless tire of the present invention mounted on a rim.
[Explanation of symbols]
1: rim 1a: rim outer periphery 2: tire body 3: inner surface of tire body 4: air chamber 5: inner liner 6: coating film (gas barrier layer)

Claims (3)

In a tubeless tire in which a tire main body mounted on an outer periphery of a rim directly forms an air chamber between an inner surface thereof and a rim, an inner surface of the tire main body has a particle diameter of 5 μm or less and an aspect ratio of 200 to A tubeless tire, wherein a gas barrier layer comprising a gas barrier resin composition containing 3000 inorganic layered compounds and a high hydrogen bonding resin is laminated as a coating film. The tubeless tire according to claim 1, wherein the content of the inorganic layered compound is 3 to 70% by weight based on the total amount of the inorganic layered compound and the high hydrogen bonding resin. The tubeless tire according to claim 1-2, wherein the high hydrogen bonding resin is polyvinyl alcohol.

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