JP3982811B2 - Tubeless tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tubeless tire that can stably maintain air pressure over a long period of time.
[0002]
[Prior art]
The tubeless tire in which the tire body mounted on the outer periphery of the rim directly forms an annular air chamber between the inner surface and the rim does not require a rubber tube and is easy to handle. It is widely used as a tire for motorcycles and is well known.
[0003]
However, since the tire body is usually made of a rubber-based material and generally has some air permeability, the air in the tire supplied to a predetermined pressure in advance gradually leaks over time and the air pressure gradually decreases. For this reason, troublesome maintenance work such as periodically inspecting the tire and refilling the air is necessary.
[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 joined or integrated on the inner surface of the tire body directly or through an adhesive resin layer. Tubeless tires have been proposed (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-177307 A (second page)
[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 does not necessarily satisfy the set air pressure retention period. It is manufactured by bonding the film to the inner surface of the tire body molded into a predetermined shape, or by shaping the tire shape after pasting the film to the tire base before molding, but in the case of the former method Since the inner surface of the tire body has a concave shape with a narrow width, it is difficult to work to uniformly bond the film to the inner surface, and uneven bonding is likely to occur, and air leakage from the portion is likely to occur. When the latter method is used, since the surface of the tire base material and the film are surface bonded, smoothness between the bonding surfaces is required, and if that is insufficient, peeling is likely to occur. How there was a problem.
[0007]
The present invention has been made in order to solve such problems, and is excellent in gas barrier properties (air impermeability), and is a tubeless tire in which a gas barrier layer is firmly laminated as a coating film on the inner surface of a tire body. Is to provide.
[0008]
[Means for Solving the Problems]
That is, the present invention is a tubeless tire in which the tire body mounted on the outer periphery of the rim directly forms an air chamber between the inner surface and the rim, the inner surface of the tire body has a particle size of 5 μm or less, The present invention provides 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-described configuration has a gas barrier layer made 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 causing uneven bonding as in the case of pasting a film. Can be maintained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[0011]
As shown in FIG. 1, for example, the basic structure of a tubeless tire used in a conventionally known automobile, motorcycle, etc. is that a tire body 2 mounted on an outer periphery 1a of a rim 1 has an inner surface 3 thereof. The air chamber 4 is directly formed between the rim 1 and the rim 1, and an inner liner 5 made of butyl rubber or the like is provided on the inner surface of the tire body in many cases.
[0012]
The tubeless tire of the present invention is known as illustrated in FIG. 1 except that the gas barrier layer specified in the present invention is laminated on the inner surface of the tire body as a coating film 6 as shown in FIG. This is basically the same as the tubeless tire, and the configuration of the tire body is not particularly limited. Therefore, the inner liner illustrated in FIG. 1 is not necessarily essential.
In the present invention, the inner surface of the tire body refers to the inner surface of the tire body that comes into contact with the air chamber when the tire body is mounted on the outer periphery of the rim. When these layers are provided, it means the inner surface of the tire body in contact with the air chamber 4 including these layers.
[0013]
The tubeless tire of the present invention has a gas barrier layer formed of a gas barrier resin composition containing an inorganic layered compound having a particle size of 5 μm or less and an aspect ratio of 200 to 3000 and a high hydrogen bonding resin on the inner surface of the tire body. It is laminated as a coating film.
[0014]
The high hydrogen bonding resin forming the gas barrier resin composition is a resin having a hydrogen bonding group or an ionic group which is a crosslinkable functional group.
Here, the hydrogen bonding group is a group capable of hydrogen bonding, and specifically includes a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, and the like. Examples of groups capable of ionic bonding include carboxylate groups, sulfonate ion groups, phosphate ion groups, ammonium groups, and phosphonium groups. 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, an ammonium group, and the like.
[0015]
The content of hydrogen bonding groups or ionic groups in the high hydrogen bonding resin (the total amount of both when both are included) is usually in the range of 20 wt% to 60 wt%, preferably 30 wt% to It is in the range of 50 wt%. The contents of these hydrogen bonding groups and ionic groups can be measured by nuclear magnetic resonance (for example, ¹ H-NMR, ¹³ C-NMR, etc.).
[0016]
Specific examples of such a high hydrogen bonding resin include polyvinyl alcohol (PVA) and modified products thereof, polysaccharides, ethylene / vinyl alcohol copolymer (EVOH) and modified products thereof, polyacrylic acid and esters thereof, Examples include sodium polyacrylate, polystyrene sulfonic acid, sodium polystyrene sulfonate, polyethyleneimine, polyallylamine and its quaternary ammonium salt, polyvinyl thiol, and polyglycerin.
[0017]
Examples of the PVA include a polymer obtained by hydrolysis or transesterification (saponification) of an acetate portion of a vinyl acetate polymer, a vinyl trifluoroacetate polymer, a vinyl formate polymer, a vinyl pivalate polymer, Examples thereof include polymers obtained by saponifying a t-butyl vinyl ether polymer, a trimethylsilyl vinyl ether polymer and the like.
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 70 mol% or more, preferably 85 mol% or more, more preferably 98 mol% or more, and most preferably a completely saponified product.
Moreover, it is preferable that the polymerization degree of PVA exists in the range of 100-20000, and it is more preferable that it exists in the range of 200-5000. Further, the above PVA may be modified with a small amount of a copolymerization monomer.
[0019]
The polysaccharide is a polymer synthesized by polycondensation of various monosaccharides, and in the present invention, those obtained by chemically modifying the polymer are also included. Examples of such polysaccharides include cellulose, cellulose derivatives (such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose), amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan and the like.
[0020]
The ethylene / vinyl alcohol copolymer (EVOH) preferably has a vinyl alcohol fraction in the range of 40 mol% to 80 mol% and 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 conditions of a temperature of 190 ° C. and a load of 2.160 g. EVOH may be modified with a small amount of a copolymerization monomer.
[0021]
There may be only one kind of such a high hydrogen bonding resin, or two or more kinds may be used in combination. Among these resins, PVA and modified products thereof, polysaccharides, EVOH and modified products thereof are preferable, and PVA is most preferable.
[0022]
The high hydrogen bonding resin may be used alone, but may be used as a copolymer with other copolymerizable monomers as long as it does not affect the gas barrier property, Can be used in combination with a resin. Examples of resins that can be used in combination include polyester resins, polyurethane resins, polyamide resins, epoxy resins, and melamine resins.
[0023]
Moreover, the high hydrogen bond resin can be blended with a cross-linking agent capable of undergoing a cross-linking reaction with the high hydrogen bond resin. There is no restriction | limiting in particular in the compounding quantity of a crosslinking agent, What is necessary is just to use an effective amount of a crosslinking agent. As the cross-linking agent, an organometallic compound is particularly preferable because it can impart a cross-linking structure to the high hydrogen bonding resin layer while maintaining flexibility. The organometallic compound used here is a compound that can form a coordination bond, a hydrogen bond, an ionic bond, or the like by a crosslinking reaction with a high 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 an appropriate crosslinking reactivity. To preferred.
[0025]
As the silicon organic compound, a silane coupling agent is particularly preferably used. As such a silane coupling agent, an organic reactive group-containing organoalkoxysilane, particularly an organoalkoxysilane having an epoxy group is suitable. Specific examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Such a silane coupling agent may be only one kind, may be used combining two or more types, and it is also preferable to use together with a metal alkoxide.
[0026]
In addition, organic crosslinking such as aldehyde crosslinking agents such as formaldehyde, acetaldehyde and gliogizar, epoxy crosslinking agents such as water-soluble polyfunctional epoxy, isocyanate crosslinking agents such as polyfunctional isocyanate compounds, and melamine crosslinking agents such as methylolated melamine. An agent is also preferably used.
[0027]
A method for 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 to prepare a coating solution to be a gas barrier layer B, coating the substrate layer A, drying it, and further proceeding 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. -Based derivative compounds (zirconium phosphate compounds), chalcogenides, clay minerals, hydrotahydrotalcite compounds, etc. Among these, clay 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, A compound represented by the chemical formula: MX ₂ . In the formula, M represents an element selected from the groups IV to VI, and X represents chalcogen (S, Se, Te).
[0029]
Among the clay minerals, smectite group, vermiculite group and mica group 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, those obtained by treating these clay minerals with organic matter (hereinafter sometimes referred to as organic modified clay minerals) ) And the like.
[0030]
The gas barrier resin composition applied to the present invention is usually prepared as a dispersion liquid composed of the above-described high hydrogen bonding resin, inorganic layered compound and dispersion medium, but among the inorganic layered compounds, the applied dispersion Those that swell and / or cleave in the medium are preferred. Specifically, those having a swelling value of 5 or more according to the following swellability test are preferred, and those having a swelling value of 20 or more are more preferred. Further, those having a cleavage value of 5 or more by cleavage test described below are preferred, and those having a cleavage value of 20 or more are more preferred.
[0031]
(Swellability test)
100 ml of solvent is put into a 100 ml graduated cylinder, and 2 g of inorganic layered compound is gradually added thereto. After standing at 23 ° C. for 24 hours, the volume (ml) of the inorganic layered compound dispersion layer is read from the scale of the interface between the inorganic layered compound dispersion layer and the supernatant in the graduated cylinder. It shows that swelling property is so high that this numerical value (swelling value) is large.
[0032]
[Cleavage test]
Gradually add 30 g of the inorganic layered compound in 1,500 ml of solvent, and disperser (manufactured by Asada Tekko Co., Ltd., Despa MH-L, blade diameter 52 mm, rotation speed 3,100 rpm, container volume 3 L, bottom-blade distance 28 mm ) At 90 ° C. for 90 minutes at a peripheral speed of 8.5 m / min, and 100 ml of this dispersion is taken into a graduated cylinder.
After standing for 60 minutes, the volume (ml) of the inorganic layered compound dispersion layer is read from the scale of the interface between the layered compound dispersion layer and the supernatant in the graduated cylinder. The larger this numerical value (cleavage value), the higher the cleavage property.
[0033]
As the 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, dimethyl sulfoxide, and acetone, and 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 (benzene, toluene, xylene, etc.), ethers (ethyl ether, tetrahydrofuran, etc.), ketones (acetone, 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, Perchloroethylene, etc.), 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 the aspect ratio is preferably in the range of 200 to 3000.
If the average particle diameter exceeds 5 μm or the aspect ratio is less than 200, the gas barrier property of the laminate is not sufficient, and it is difficult to obtain and produce an inorganic layered compound having an aspect ratio of greater than 3000.
[0035]
Here, the particle size of the inorganic stratiform compound indicates a particle size (volume-based median diameter) obtained by a known method using a diffraction / scattering method in a dispersion medium. That is, the particle size distribution is calculated from the diffraction / scattering pattern obtained when light passes through the inorganic layered compound dispersion by the Mie scattering theory, etc. It can ask for.
In addition, when the inorganic layered compound is sufficiently swollen and cleaved with the same kind of dispersion medium as used in the diffraction / scattering method, and this is combined with a resin, the swelling / The particle size of the cleaved inorganic layered compound is substantially equal to the particle size of the swollen and cleaved inorganic layered compound in the dispersion medium.
[0036]
The aspect ratio (Z) of the inorganic layered compound is a value determined using the formula: Z = L / a. Here, L represents the average particle diameter of the inorganic layered compound obtained by the diffraction / scattering method described above, and a represents 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 Doujinsha, supervised by Jiro Shiokawa, p. 69)). it can.
[0038]
The aspect ratio (Z) obtained as described above is not necessarily exactly equal to the true aspect ratio of the inorganic layered compound in the gas barrier layer (coating film), but this aspect ratio (Z) is not the same as the gas barrier layer. It can be regarded as the aspect ratio of the inorganic layered compound.
[0039]
In the present invention, the “aspect ratio” of the inorganic layered compound means the “aspect ratio (Z)” defined above, and the “particle diameter” indicates “the particle diameter L determined by the diffraction / scattering method”. Shall.
[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 usually in the range of 3 to 70% as a weight ratio in the total amount of the inorganic layered compound and the high hydrogen bonding resin.
[0041]
Further, in the gas barrier resin composition containing the inorganic stratiform compound and the high hydrogen bonding resin composition, unless particularly adversely affected as a tubeless tire, an ultraviolet absorber, a colorant, an antioxidant, a surfactant, etc. Various additives may be included. Although it does not specifically limit as said surfactant, For example, anionic surfactant, cationic surfactant, zwitterionic surfactant, and nonionic surfactant are mentioned.
[0042]
The tubeless tire of the present invention is formed by laminating a gas barrier layer made of the gas barrier resin composition as a coating film, and 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 viewpoints of target gas barrier properties and economy.
[0043]
Further, the coating film may be only one layer, or may be a multilayer coating structure as necessary.
[0044]
There is no particular limitation on the method of laminating a gas barrier layer comprising a bus barrier resin composition comprising an inorganic layered compound and a high hydrogen bonding resin on the inner surface of the tire body as a coating film. A coating solution prepared by dissolving or dispersing the functional resin and the third component as described above in a solvent, if necessary, so that the coating solution has a desired thickness by a method such as spraying or brushing. The coating liquid is applied to the inner surface of the tire body shaped into a predetermined shape and then the solvent is removed, or the coating liquid is applied to the tire base material before shaping into the tire shape by a roll coater, slit coater, bar There is a method in which the coating is performed by a normal coating method such as a coater, and then the solvent is removed and then the tire is shaped.
In this case, the thickness of the coating film does not necessarily have to be uniform on the inner surface of the tire. Depending on the tire configuration, for example, the tread portion of the tire is relatively thin, and the side wall portion and the bead portion are appropriately thickened. Also good.
[0045]
In the preparation of the coating solution, the inorganic layered compound and the resin may be added separately or in advance and then added to the solvent (dispersion medium). For example, (1) the high hydrogen bonding resin is dissolved in the solvent. And (2) adding the dispersion liquid in which the inorganic stratiform compound is dispersed to the high hydrogen bonding resin, and adding the resin to the dispersion liquid. (3) A method in which an inorganic layered compound is added to a solution obtained by dissolving a high hydrogen bonding resin in a solvent and the inorganic layered compound is dispersed in the solution to form a dispersion is preferably used. It is done.
[0046]
Examples of the solvent (dispersion medium) in this case include a dispersion medium used when the inorganic layered compound is swollen and / or cleaved, and water, alcohol, or a water-alcohol mixture is particularly preferably used. .
The amount of the dispersion medium used is appropriately determined depending on conditions such as the type of the dispersion medium, coating conditions such as a coating method, and a desired thickness of the coating film, and is not particularly limited.
[0047]
In the method for preparing the coating liquid, the inorganic layered compound is preferably dispersed as finely and uniformly as possible in the coating liquid. As such a method, a high-pressure dispersion treatment known as a dispersion method for adjusting the coating liquid is used. Preferably it is done.
[0048]
When applying the coating liquid, surface treatment such as anchor treatment, corona treatment, flame plasma treatment, ozone treatment, electron beam treatment, etc. is applied to the coated surface in advance for the purpose of improving adhesion (adhesiveness) with the coated surface. It is effective to apply it.
[0049]
For example, when an anchor layer is provided on the coating surface as an anchoring treatment, the material used as the anchor layer can improve the adhesion between the coating surface to which the coating liquid is applied and the coating film that is a gas barrier layer. Although there is no particular limitation as long as it is present, for example, polyethyleneimine series, alkyl titanate series, polybutadiene series, urethane series, ionomer series, and the like can be mentioned. The material for the anchor layer is preferably a urethane system prepared from an isocyanate compound and an active hydrogen compound from the viewpoint of water resistance.
[0050]
As a method for the anchor treatment, a conventionally known method applied when forming a gas barrier layer comprising a gas barrier resin composition containing an inorganic layered compound and a high hydrogen bonding resin is not particularly limited.
The thickness of the anchor layer is also arbitrary, but is usually 0.03 μm to 2.0 μm, preferably 0.05 μm to 1.0 μm.
[0051]
The tubeless tire of the present invention is formed by laminating a gas barrier layer made of a bus barrier resin composition containing an inorganic layered compound and a high hydrogen bonding resin as a coating film on the inner surface of the tire body as described above. The coating film does not necessarily have to be on the outermost surface of the inner surface of the tire body, and a protective layer may be further provided on the surface of the laminated coating film as necessary.
Thereby, 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 is not necessarily provided on the entire surface of the coating film made of the gas barrier layer, and may be provided only on the inner surface of the outer peripheral portion of the tire to be attached to the rim.
[0052]
Such a protective layer is not particularly limited as long as it has adhesiveness with the coating film and has a certain degree of mechanical strength. However, it is preferable that the coating film can be further coated with a resin dispersion or a resin solution as in the previous coating film.
[0053]
【The invention's effect】
The tubeless tire of the present invention has an extremely excellent gas barrier property itself, and since 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. As a result, the air retention property 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 a tubeless tire of the present invention in a state where it is mounted on a rim.
[Explanation of symbols]
1: Rim 1a: Rim outer peripheral part 2: Tire body 3: Tire inner surface 4: Air chamber 5: Inner liner 6: Coating film (gas barrier layer)

Claims (3)

In 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, the inner surface of the tire body has a particle size of 5 μm or less and an aspect ratio of 200 to 200. A tubeless tire comprising a gas barrier layer made of a gas barrier resin composition containing 3000 inorganic layered compounds and a high hydrogen bonding resin, laminated as a coating film. The tubeless tire according to claim 1, wherein the content of the inorganic stratiform compound is 3 to 70% as a weight ratio in the total amount of the inorganic stratiform compound and the high hydrogen bonding resin. The tubeless tire according to claim 1-2, wherein the high hydrogen bonding resin is polyvinyl alcohol.

Images