JP4326794B2 - Pneumatic tire - Google Patents

Description

【００６６】
【表２】

【００６７】
【表３】

【００６８】
本発明のゴム配合および／またはガスバリアー層配合を使用しなかった試験例１〜７、９、１０、１２、１３および１５では、ゴム組成物の空気透過係数が高く、好ましくなかった。
【００６９】
一方、ゴム配合Ｃ〜Ｅおよびガスバリアー層塗工液１を使用した試験例８、１１および１４では、空気透過係数が低く、優れた結果が得られた。
【００７０】
また、本発明のゴム配合および／またはガスバリアー層配合を使用しなかった比較例１および２では、タイヤの内圧低下率が高く、好ましくなかった。
【００７１】
一方、実施例１および２では、内圧低下率が低く、優れた結果が得られた。
【００７２】
【発明の効果】
本発明によれば、インナーライナー層の内面側に、アンカーコート層を介して空気透過性を大幅に低減し得るガスバリアー層を積層させることで、亀裂を発生させることなく、内圧保持性が大幅に改善された空気入りタイヤ、すなわち、空気透過性が大幅に低減された空気入りタイヤを得ることができる。また、空気透過性が大幅に低減されるため、その分だけインナーライナー層を薄肉化することができ、タイヤの軽量化、ひいては低燃費化が達成され得る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire with significantly reduced air permeability.
[0002]
[Prior art]
A pneumatic tire can support a load by introducing air into the tire and can exhibit various characteristics such as ride performance. Therefore, it is very important to maintain the air pressure in the tire.
[0003]
Therefore, usually, an inner liner layer made of rubber having low air permeability such as butyl rubber or halogenated butyl rubber is provided on the inner surface of the pneumatic tire.
[0004]
On the other hand, reducing fuel consumption is one of the major technical issues in automobiles, and as part of this, demands for reducing the weight of pneumatic tires are becoming increasingly strong.
[0005]
In order to satisfy these requirements, there is an urgent need to develop an inner liner with further reduced air permeability. If such a rubber composition for an inner liner can be obtained, the inner liner layer can be thinned and the weight of the tire can be reduced.
[0006]
As an inner liner of a pneumatic tire, techniques using various materials instead of rubber having low air permeability such as butyl rubber have been proposed. For example, Patent Document 1 discloses that a solution or dispersion of a synthetic resin such as polyvinylidene chloride, saturated polyester resin, or polyamide resin having lower air permeability is applied to the inner surface of a tire. However, the technique disclosed in this document has a problem in the adhesion between the rubber layer inside the pneumatic tire and the synthetic resin layer, and the inner liner is inferior in moisture resistance.
[0007]
Patent Document 2 discloses that the inner surface of a tire is halogenated and a polymer film of methoxymethylated nylon, copolymer nylon, a mixture of polyurethane and polyvinylidene chloride, or a mixture of polyurethane and polyvinylidene fluoride is formed thereon. Has been.
[0008]
Patent Document 3 discloses a pneumatic tire having a methoxymethylated nylon thin film as an inner liner layer. Specifically, a solution of methoxymethylated nylon is applied to the inner surface of a green tire or the inner surface of a vulcanized tire. Or it is disclosed to spray or apply the emulsion. However, the techniques disclosed in these documents have the disadvantage that it is difficult to maintain the uniformity of the film thickness in addition to the disadvantage that the water resistance of the thin film is poor.
[0009]
In Patent Document 4, a thin film having a low air permeability layer made of a polyvinylidene chloride film or an ethylene vinyl alcohol copolymer film and an adhesive layer made of a polyolefin-based film, an aliphatic polyamide film or a polyurethane film is used as a tire. There is an example used as an air permeation prevention layer. However, in this system, the low air permeability layer lacks flexibility, and the thin film cannot follow the material expansion and contraction during tire running, which sometimes causes cracks.
[0010]
In Patent Document 5, a composition containing carbon black, a plasticizer and a vulcanizing agent in a rubber obtained by halogenating a copolymer of an isomonoolefin having 4 to 7 carbon atoms and paraalkylstyrene is used for an inner liner. It has been proposed. However, such an inner liner is insufficient in reducing air permeability, and further weight reduction of the tire is not appropriate.
[0011]
In addition, a rubber composition in which a polyamide resin, a polyester resin, a polynitrile resin, a cellulose resin, a fluorine resin, an imide resin, and an elastomer are mixed or dynamically crosslinked as disclosed in Patent Documents 6 to 10 is used as an inner liner. It has been proposed to be used. However, in these rubber compositions, it is very difficult to follow the expansion and contraction of other rubber materials during processing such as tire molding and vulcanization, and cracks may occur during running.
[0012]
[Patent Document 1]
Japanese Examined Patent Publication No. 47-31761
[Patent Document 2]
JP-A-5-330397
[Patent Document 3]
JP-A-5-318618
[Patent Document 4]
JP-A-6-40207
[Patent Document 5]
Japanese National Patent Publication No. 5-508435
[Patent Document 6]
JP-A-8-259741
[Patent Document 7]
JP-A-11-199713
[Patent Document 8]
JP 2000-63572 A
[Patent Document 9]
JP 2000-159936 A
[Patent Document 10]
JP 2000-160024 A
[0013]
[Problems to be solved by the invention]
As described above, various proposals have been made to use a composition having low air permeability for the inner liner, but it has not yet been put into practical use. Accordingly, an object of the present invention is to provide a pneumatic tire in which the internal pressure retention is greatly improved. That is, an object of the present invention is to provide a pneumatic tire in which air permeability is greatly reduced.
[0014]
[Means for Solving the Problems]
As a result of intensive studies to improve the above problems, a gas barrier layer composed of an inorganic layered compound having a specific particle size and aspect ratio and a resin is formed into an inner liner layer composed of a specific rubber component via an anchor coat layer. It has been found that the air permeability of the pneumatic tire is greatly reduced by laminating on the inner surface side, and the present invention has been completed.
[0015]
That is, the present invention provides at least one butyl selected from the group consisting of a butyl rubber, a halogenated butyl rubber, and a halide of a copolymer of isomonoolefin having 4 to 7 carbon atoms and paraalkyl styrene as the rubber component. And 60 to 100% by weight of a rubber, and 0 to 40% by weight of at least one diene rubber selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber and styrene-isoprene-butadiene rubber. The present invention relates to a pneumatic tire having a gas barrier layer made of an inorganic layered compound and resin having an average particle size of 5 μm or less and an average aspect ratio of 50 to 5000 on an inner surface side of an inner liner layer made of a rubber composition comprising an anchor coat layer. .
[0016]
The inorganic layered compound is a clay mineral having a swelling property that swells and cleaves in a solvent, and the resin is a high hydrogen bonding resin made of polyvinyl alcohol or a polysaccharide. In the gas barrier layer, the inorganic layered compound and The resin is preferably mixed at a volume ratio of 5/95 to 90/10.
[0017]
The gas barrier is obtained by dispersing the inorganic layered compound in a resin or a resin solution in a state of being swollen and cleaved in a solvent, and coating the inner layer side of the inner liner layer while maintaining the state, and then removing the solvent from the system. It is preferred that a layer be obtained.
[0018]
The thickness of the gas barrier layer is preferably 0.5 mm or less.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The pneumatic tire of the present invention has a gas barrier layer on the inner surface side of an inner liner layer made of a rubber composition containing a butyl rubber via an anchor coat layer.
[0020]
The rubber composition in the inner liner layer contains 60 to 100% by weight, preferably 70 to 100% by weight, of a butyl rubber as a rubber component. If the ratio of the butyl rubber to the rubber component is less than 60% by weight, the air permeability is not sufficiently reduced. These ratios are higher than the ratio at which butyl rubber having low air permeability can be present as a main component (sea layer).
[0021]
The butyl rubber is selected from the group consisting of butyl rubber (IIR), halogenated butyl rubber (X-IIR), and halides of copolymers of 4 to 7 carbon monoisoolefin and paraalkylstyrene. 1 type or 2 types or more are included. The halogen in the halogenated butyl rubber and halide is preferably chlorine or bromine.
[0022]
Among these butyl rubbers, X-IIR or a halide of a copolymer of an isomonoolefin having 4 to 7 carbon atoms and paraalkyl styrene is preferable because of particularly excellent adhesion to the lower layer. Among them, a halide of a copolymer of an isomonoolefin having 4 to 7 carbon atoms and paraalkyl styrene is more preferable.
[0023]
In the rubber component, examples of the rubber component other than the butyl rubber include diene rubber. The diene rubber is contained in the rubber component in an amount of 0 to 40% by weight, preferably 0 to 30% by weight. When the proportion of the diene rubber in the rubber component exceeds 40% by weight, the content of the butyl rubber is lowered, and as a result, the air permeability is not sufficiently reduced.
[0024]
The diene rubber is a rubber selected from the group consisting of natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR) and styrene-isoprene-butadiene rubber (SIBR). 1 type or 2 types or more are included. Of these, NR is preferred because of its high strength.
[0025]
In the inner liner layer of the pneumatic tire of the present invention, in addition to the rubber component, a general additive used for compounding rubber for tires, such as carbon black, nM.xSiOy.zH ₂ O (wherein n represents an integer of 1 to 5, M represents at least one metal selected from Al, Mg, Ti, and Ca, a metal oxide, a metal hydroxide, or a carbonate thereof, and x represents 0 Represents an integer of 10 to 10, y represents an integer of 2 to 5, and z represents an integer of 0 to 10.) Inorganic powder such as silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, hydroxide Magnesium, alumina, clay, talc, magnesium oxide, and other plasticizers such as chemical oils, tackifiers, crosslinking agents such as sulfur and zinc white, vulcanization accelerators, crosslinking aids, and the like can be appropriately blended.
[0026]
In the pneumatic tire of the present invention, the anchor coat layer is applied to the inner surface side of the inner liner layer. The thickness of the anchor coat layer is preferably 0.1 to 500 μm, particularly preferably 0.5 to 100 μm. When the thickness of the anchor coat layer is less than 0.1 μm, sufficient adhesive force tends to be not obtained, and when it exceeds 500 μm, peeling at the anchor coat layer tends to occur.
[0027]
The anchor coat layer is a layer between the inner liner layer and the gas barrier layer containing the inorganic layered compound and the resin, and bonds the inner liner layer and the gas barrier layer. Therefore, the anchor coat layer is laminated between the inner liner layer and the gas barrier layer. The lamination method is not particularly limited, but a coating method using an anchor coating agent solution in which an anchor coating agent is dissolved in a solvent is preferable.
[0028]
The anchor coating agent is preferably at least one selected from the group consisting of a polyethyleneimine anchor coating agent, an alkyl titanate anchor coating agent, a polybutadiene anchor coating agent, and a polyurethane anchor coating agent. Of these, polyurethane anchor coating agents are preferred because of their excellent adhesion to rubber.
[0029]
The polyurethane anchor coating agent is prepared from an isocyanate compound and an active hydrogen compound.
[0030]
Examples of the isocyanate compound include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), and 4,4′-methylenebiscyclohexyl isocyanate (H12MDI). And isophorone diisocyanate (IPDI).
[0031]
The active hydrogen compound only needs to have a functional group that binds to an isocyanate compound. For example, ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, Low molecular weight polyol such as trimethylolpropane, polyethylene glycol, polyoxypropylene glycol, ethylene oxide / propylene oxide copolymer, polyether polyol such as polytetramethylene ether glycol, poly-β-methyl-δ-valerolactone, polycaprolactone, And polyester polyols such as polyesters from diol / dibasic acids.
[0032]
Among the active hydrogen compounds, a low molecular weight polyol is preferable, and a low molecular weight diol is particularly preferable. Examples of such diols include ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and the like. Examples of the dibasic acid include adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid and the like. Other polyols include active hydrogen compounds such as castor oil, liquid polybutadiene, epoxy resin, polycarbonate diol, acrylic polyol, and neoprene (registered trademark).
[0033]
The mixing ratio of the isocyanate compound and the active hydrogen compound is not particularly limited, but it is preferable to determine the mixing ratio in consideration of the equivalent relationship between the isocyanate group and the active hydrogen group, for example, —OH, —NH, —COOH. For example, the ratio R (R = AN / BN) of the number of moles of isocyanate groups (AN) to the number of moles of active hydrogen groups (BN) of the active hydrogen compound is preferably 0.001 or more from the viewpoint of adhesive strength. From the viewpoints of property and blocking, 10 or less is preferable. The mole ratio R is more preferably in the range of 0.01-1. The number of moles of isocyanate groups and active hydrogen groups is ¹ H-NMR, ¹³ It can be quantified by C-NMR.
[0034]
The solvent in the anchor coating agent solution is mainly an organic solvent, and alcohols, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, ethers, halogenated hydrocarbons. And mixed solvents thereof.
[0035]
The pneumatic tire of the present invention is formed by laminating a gas barrier layer made of an inorganic layered compound and a resin via the anchor coat layer. A gas barrier layer is a layer with low air permeability, and can reduce the air permeability of a tire.
[0036]
The inorganic layered compound used for the gas barrier layer in the present invention is an inorganic compound in which unit crystal layers are stacked on each other to have a layered structure, and has an average particle size of 5 μm or less and an average aspect ratio of 50 to 5000. If it is, it will not be specifically limited.
[0037]
The average particle diameter of the inorganic layered compound is 5 μm or less, preferably 1 μm or less. If the average particle size is larger than 5 μm, the processability during tire production is lowered, and the air permeability is not reduced. Here, an average particle diameter means the average value of the long diameter of an inorganic layered compound.
[0038]
The average aspect ratio of the inorganic layered compound is 50 to 5000, and is preferably 200 to 3000 from the viewpoint that the effect of reducing air permeability is particularly excellent. If the average aspect ratio is less than 50, the air permeability is not sufficiently lowered, and if it is greater than 5000, it is technically difficult and economically expensive. Here, the average aspect ratio refers to the average value of the ratio of the inorganic layered compound to the major axis thickness.
[0039]
Specific examples of the inorganic layered compound include graphite, phosphate derivative compounds (zirconium phosphate compounds), chalcogenides, clay minerals, and the like.
[0040]
As the inorganic layered compound having a large aspect ratio, an inorganic layered compound that swells and cleaves in a solvent is preferably used. Among these, clay minerals having swelling properties are preferable. The clay mineral has a two-layer structure having an octahedral layer with aluminum or magnesium as a central metal on the upper part of a silica tetrahedral layer, and the silica tetrahedral layer has aluminum or magnesium as a central metal. It is classified into a type having a three-layer structure in which an octahedral layer is sandwiched from both sides. Examples of the former include kaolinite group and antigolite group. Examples of the latter include smectite group, vermiculite group, mica group and the like depending on the number of interlayer cations. Specifically, kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, pyroferrite, montmorillonite, hectorite, tetrasillicum mica, sodium teniolite, muscovite, margarite, talc, vermiculite, phlogopite , Xanthophyllite, chlorite and the like. Of these, tetrasilica mica is preferable from the viewpoint of cost and dispersibility.
[0041]
The solvent for swelling the inorganic layered compound is not particularly limited. For example, in the case of a natural swelling clay mineral, alcohols such as water, methanol, ethanol, propanol, isopropanol, ethylene glycol, and diethylene glycol, dimethylformamide, dimethyl sulfoxide, Examples thereof include acetone, and alcohols such as water and methanol are preferable.
[0042]
The resin used for the gas barrier layer in the present invention is not particularly limited. For example, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), polysaccharides And polyacrylic acid and esters thereof. Preferable examples include high-hydrogen bonding resins in which the weight percentage of hydrogen bonding groups or ionic groups per unit weight of the resin satisfies a ratio of 20 to 60%, particularly 30 to 50%. If the weight percentage of the hydrogen bonding group or ionic group is less than 20%, there is a tendency that sufficient dispersibility of the inorganic layered compound is not obtained, and if it exceeds 60%, the water resistance of the resin after forming the gas barrier layer is low. There is a tendency to be inferior.
[0043]
Examples of the hydrogen bonding group of the high hydrogen bonding resin include a hydroxyl group, an amino group, a thiol group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Examples of the ionic group include a carboxylate group, a sulfonate ion group, a phosphate ion group, an ammonium group, and a phosphonium group. Of these, preferred hydrogen bonding groups or ionic groups include 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.
[0044]
Specific examples of the high hydrogen bonding resin include, for example, polyvinyl alcohol, an ethylene-vinyl alcohol copolymer having a vinyl alcohol fraction of 41 mol% or more, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, amylose, amylopectin, pullulan, Polysaccharides such as curdlan, xanthan, chitin, chitosan, cellulose, polyacrylic acid, sodium polyacrylate, polybenzenesulfonic acid, sodium polybenzenesulfonate, polyethyleneimine, polyallylamine, its ammonium salt polyvinylthiol, poly Examples include glycerin.
[0045]
Among the high hydrogen bond resins, polyvinyl alcohol or polysaccharide is preferable from the viewpoint of barrier properties. The term “polyvinyl alcohol” as used herein refers to a product obtained by hydrolyzing the acetate portion of a vinyl acetate copolymer, and is precisely a copolymer of vinyl alcohol and vinyl acetate. Here, the proportion of saponification is preferably 70% or more, and more preferably 85% or more, in terms of mole percentage. The polymerization degree is preferably 100 to 5000.
[0046]
The polysaccharide referred to here is a biopolymer synthesized in a biological system by condensation polymerization of various monosaccharides, and here includes those chemically modified based on them. Examples thereof include cellulose and cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan and the like.
[0047]
When the resin is used as a solution, the solvent is not particularly limited, and examples thereof include water, alcohols, dimethylformamide, acetone and the like, and water and alcohols are preferable in view of processability and safety.
[0048]
The composition ratio (volume ratio) of the inorganic layered compound and the resin used in the present invention is preferably 5/95 to 90/10, particularly preferably 5/95 to 50/50. When the volume fraction of the inorganic layered compound is smaller than 5/95, the air permeability is not sufficiently lowered, and when it is larger than 90/10, the film forming property is not good.
[0049]
In the pneumatic tire of the present invention, the gas barrier layer made of the inorganic layered compound and the resin is laminated on the inner surface side of the inner liner layer in the form of a film. The blending method of the composition comprising the inorganic layered compound and the resin is not particularly limited. For example, a method of mixing a resin or a solution in which a resin is dissolved and a dispersion in which the inorganic layered compound is previously swollen and cleaved, inorganic Examples thereof include a method of adding a dispersion obtained by swelling and cleaving a layered compound to the resin, a method of thermally kneading the resin and the inorganic layered compound, and the like. As the method for obtaining a composition containing an inorganic layered compound having a particularly large aspect ratio, the former two are preferred.
[0050]
The method for laminating the gas barrier layer used in the present invention on the substrate such as the inner surface of the inner liner layer is not particularly limited, but after applying the gas barrier layer coating liquid to the substrate surface, it is dried. Examples thereof include a coating method in which the solvent is removed from the system and heat treatment is performed, and a method in which a gas barrier layer is laminated on a substrate later. Of these, the coating method is preferable from the viewpoint of processability. The thickness of the gas barrier layer by the coating method is preferably 0.5 mm or less, particularly preferably 0.5 to 100 μm. If the thickness of the gas barrier layer is greater than 0.5 mm, the gas barrier layer tends to crack due to deformation during tire running. On the other hand, if it is thinner than 0.5 μm, the effect of reducing the air permeability tends to be small.
[0051]
Moreover, as a method of coating the base material, a method of applying a coating solution to the inner surface side of the inner liner layer in a tire raw cover state and a method of applying a coating solution to a vulcanized tire are used.
[0052]
In the pneumatic tire of the present invention, the air permeability can be greatly reduced without lowering the workability and productivity. This is because by laminating an inorganic layered compound having a large aspect ratio and a gas barrier layer made of resin on the inner surface side of the inner liner layer, the inorganic layered compound can be sufficiently absorbed on the inner surface side of the inner liner layer. This is because they are laminated in a dispersed state.
[0053]
In the pneumatic tire of the present invention, since the gas barrier layer is a thin film, the gas barrier layer can sufficiently follow the material expansion and contraction during running of the tire, and there is no possibility of cracking.
[0054]
【Example】
EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to only these examples. In addition, the following each material was used for the rubber composition used by the Example and the comparative example.
[0055]
(material)
NR: RSS # 3 manufactured by Tech Bee Hang
Br-IIR: Exon bromobutyl 2255
GPF: Seast V made by Tokai Carbon Co., Ltd.
Resin: ESCOREZ 1102 made by Esso
Oil A: JOMO Process X140 manufactured by Japan Energy Co., Ltd.
Oil B: Machine oil 22 manufactured by Showa Shell Sekiyu KK
Stearic acid: Stearic acid manufactured by NOF Corporation
Zinc flower: Zinc flower No. 1 made by Mitsui Metal Mining Co., Ltd.
Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd.
Vulcanization accelerator NS: Noxeller NS (N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator DM: Noxeller DM manufactured by Ouchi Shinsei Kagaku Kogyo Co., Ltd.
[0056]
(Rubber composition and tire processing method)
In accordance with the formulation shown in Table 1, a masterbatch was prepared by kneading compounding agents other than sulfur, zinc white and vulcanization accelerator in a BR type Banbury, and then masterbatch and sulfur, zinc white in an 8-inch roll. Then, vulcanization accelerators were kneaded to obtain various test rubber compositions (rubber formulations A to E). These blends are press vulcanized at 170 ° C. for 15 minutes to produce vulcanizates, or these blends are used for the inner liner layer of a pneumatic tire to produce each tire by a normal method. did.
[0057]
(Method for producing gas barrier layer coating solution)
・ Gas barrier layer coating solution 1
Synthetic mica (tetrasilica mica (Na-Ts); manufactured by Topy Industries Co., Ltd.) was dispersed in ion-exchanged water so as to be 0.65% by weight, and this was dispersed with an inorganic layered compound dispersion (liquid A). did. This synthetic mica (Na-Ts) had an average particle size of 977 nm and an average aspect ratio of 1043. Also, ion exchange of polyvinyl alcohol (PVA210; manufactured by Kuraray Co., Ltd., weight percentage of hydrogen bonding group or ionic group per unit weight of the resin: 38%, degree of saponification: 88.5%, degree of polymerization: 1000) This was dissolved in water to a concentration of 0.325% by weight, and this was used as a resin solution (liquid B). A liquid and B liquid were mixed so that each solid component ratio (volume ratio) might be inorganic layered compound / resin = 3/7, and this was used as gas barrier layer coating liquid 1.
[0058]
・ Gas barrier layer coating solution 2
Polyvinyl alcohol (PVA210; manufactured by Kuraray Co., Ltd.) similar to that used in the gas barrier layer coating solution 1 is dissolved in ion-exchanged water to a concentration of 0.325% by weight, and this is applied to the gas barrier layer coating. Liquid 2 was obtained.
[0059]
Test Examples 1 to 15 (Evaluation with rubber composition)
(Film forming method)
As shown in Table 2, on the various vulcanized rubber compositions (rubber blends A to E), a polyurethane anchor coating agent (Adcoat AD335A / CAT10L = 15/1 (weight ratio); manufactured by Toyo Morton Co., Ltd.) After coating, the various gas barrier layer coating solutions were casted, and then heat treated at 100 ° C. for 10 minutes. The film thickness obtained by these treatments was about 1 μm for the anchor coat layer and about 2 μm for the gas barrier layer. About these, the characteristic shown below was evaluated. In each test example, the gas barrier layer coating solution 1 was formed as “1”, and the gas barrier layer coating solution 2 was formed as “2”. Expressed in
[0060]
(Air permeability evaluation)
In accordance with JIS K7126 “Plastic Film and Sheet Gas Permeability Test Method (Method A)”, the test gas was air (nitrogen: oxygen = 8: 2), the test temperature was 25 ° C., and the air permeability coefficient was measured. . The lower the value, the lower the air permeability. The results are shown in Table 2.
[0061]
Examples 1-2 and Comparative Examples 1-2 (Evaluation with tires)
(Film forming method)
In Test Examples 2, 11, 13 and 14, 195 / 65R14 tires were prepared and vulcanized using the rubber blends selected respectively for the inner liner layer.
[0062]
The anchor coat agent and then the gas barrier layer coating solution used in each test example were applied and dried on the inner surface of the inner liner layer of the vulcanized tire using a predetermined spray gun. After that, heat treatment was performed at 100 ° C. for 10 minutes. The film thickness obtained by these treatments was about 1 μm for the anchor coat layer and about 2 μm for the gas barrier layer. About these, the characteristic shown below was evaluated.
[0063]
(Internal pressure reduction rate evaluation)
The tire was allowed to stand at room temperature of 25 ° C. for 3 months under an initial internal pressure of 200 kPa and no load condition, and the pressure was measured every four measurement intervals. Elapsed days t, initial pressure P ₀ And measured pressure P in days t _t As
Function: P _t / P ₀ = Exp (-αt)
Then, the α value was determined. The obtained α and t = 30 were substituted into the following equation to obtain β.
β = {1-exp (−αt)} × 100
[0064]
This β value was defined as the rate of decrease in internal pressure per month (% / month). The results are shown in Table 3.
[0065]
[Table 1]

[0066]
[Table 2]

[0067]
[Table 3]

[0068]
In Test Examples 1 to 7, 9, 10, 12, 13, and 15 in which the rubber compounding and / or the gas barrier layer compounding of the present invention were not used, the air permeability coefficient of the rubber composition was high, which was not preferable.
[0069]
On the other hand, in Test Examples 8, 11 and 14 using the rubber blends C to E and the gas barrier layer coating solution 1, the air permeability coefficient was low, and excellent results were obtained.
[0070]
Further, Comparative Examples 1 and 2 in which the rubber compounding and / or the gas barrier layer compounding of the present invention were not used were not preferable because the tire internal pressure reduction rate was high.
[0071]
On the other hand, in Examples 1 and 2, the rate of decrease in internal pressure was low, and excellent results were obtained.
[0072]
【The invention's effect】
According to the present invention, a gas barrier layer that can significantly reduce the air permeability is laminated on the inner surface side of the inner liner layer via the anchor coat layer, so that internal pressure retention is greatly improved without causing cracks. Thus, it is possible to obtain a pneumatic tire with improved air quality, that is, a pneumatic tire with significantly reduced air permeability. Further, since the air permeability is greatly reduced, the inner liner layer can be made thinner by that amount, and the weight reduction of the tire and the lower fuel consumption can be achieved.

Claims (5)

As the rubber component, 60 to 100% by weight of halogenated butyl rubber and at least one diene rubber selected from the group consisting of natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber and styrene-isoprene-butadiene rubber 0 Through the anchor coat layer using the polyurethane-based anchor coat agent on the inner surface side of the inner liner layer made of a rubber composition containing -40% by weight,
A pneumatic tire having a gas barrier layer made of an inorganic layered compound having an average particle size of 5 μm or less and an average aspect ratio of 50 to 5000 and a high hydrogen bonding resin that is polyvinyl alcohol or polysaccharide ,
A pneumatic tire in which the thickness of the gas barrier layer is 0.5 mm or less . The inorganic layered compound is clay mineral having a swelling property to swelling and cleavage in a solvent, are mixed the inorganic layered compound and said high hydrogen bond resin before SL gas barrier layer in a volume ratio of 5 / 95-90 / 10 The pneumatic tire according to claim 1.   The gas barrier is obtained by dispersing the inorganic layered compound in a resin or a resin solution in a state of being swollen and cleaved in a solvent, and coating the inner layer side of the inner liner layer while maintaining the state, and then removing the solvent from the system. The pneumatic tire according to claim 1 or 2, wherein a layer is obtained. The pneumatic tire of claim 1, wherein thickness is 0.5~2μm of the gas barrier layer. The pneumatic tire of claim 1, wherein a thickness of 2μm of the gas barrier layer.