JPH09216502A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a light weight of a tire, and to obtain an excellent adhesiveness with a rubber layer and an excellent durability, by laminating a thin film of an alkoxyl alkylating aliphatic polyamide resin composite with polymalization degree in a specific scope, as an air permeation preventive layer. SOLUTION: A carcass layer 2 is mounted between a pair of left and right bead cores 1, and an inner layer 3 is provided on the tire inner surface at the inner side of the carcass layer 2. An air preventive layer can be provided at a random position inside the tire, that is, at the inner or outer side of the carcass layer, at the inner or outer side of a rubber layer provided neighboring the carcass layer, or some other position. By using an alkoxyl alkylating aliphatic polyamide with a polymerization degree from 300 to 500 as an air preventive layer, a layer having a property necessary as an inner liner layer 3, and an air permeability, and a good durability of the tire in the practical condition, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to reduce the weight of a tire without impairing the air pressure retaining property in the tire, and to have excellent adhesiveness with a rubber layer and excellent air permeability and flexibility. The present invention relates to a pneumatic tire having a prevention layer.

[0002]

2. Description of the Related Art Reducing the fuel consumption rate is one of the major technical problems in automobiles, and as part of this measure, there is an increasing demand for weight reduction of pneumatic tires.

By the way, an inner liner layer made of rubber having a low gas permeability such as halogenated butyl rubber is provided on the inner surface of the pneumatic tire in order to keep the tire air pressure constant. However, since halogenated butyl rubber has a large hysteresis loss, when waving occurs in the carcass inner surface rubber and the inner liner layer in the gap between the carcass cords after vulcanization of the tire,
Since the inner liner rubber layer is deformed along with the deformation of the carcass layer, there is a problem that rolling resistance increases. Therefore, generally, the inner liner layer (halogenated butyl rubber) and the inner surface rubber of the carcass layer are bonded to each other via a rubber sheet called tie rubber having a small hysteresis loss. Therefore, in addition to the thickness of the inner liner layer of the halogenated butyl rubber, the thickness of the tie rubber is added, resulting in a thickness exceeding 1 mm (1000 μm) as a whole, which results in an increase in the weight of the product tire. Had become one.

Techniques have been proposed in which various materials are used in place of low gas permeability rubber such as butyl rubber for the air permeation preventive layer of pneumatic tires. For example, Japanese Patent Publication No. 47-3
No. 1761 discloses that an inner surface of a vulcanized tire has an air permeability coefficient [cm ³ (standard state) / cm · sec · mmHg] of 1.0 × 10 ⁻¹² or less at 30 ° C. and 5.0 × at 70 ° C. It is disclosed that a solution or dispersion of synthetic resin such as polyvinylidene chloride, saturated polyester resin or polyamide resin of 10 ^-12 or less is applied at 0.1 mm or less.

However, the technique disclosed in this publication is
It is stated that a synthetic resin coating layer having a specific air permeability coefficient is provided on the inner peripheral surface of the carcass of the vulcanized tire or the inner peripheral surface of the inner liner so that the thickness of the synthetic resin coating layer is 0.1 mm or less. However, the pneumatic tire described in this publication has a problem in adhesiveness between rubber and synthetic resin, and when a polyamide resin is used as an inner liner layer, heat resistance and moisture resistance (or It has a drawback of being inferior in water resistance. It should be noted that this publication does not describe the use of alkoxyalkylated polyamide.

Japanese Unexamined Patent Publication (Kokai) No. 5-318618 discloses a pneumatic tire using a methoxymethylated nylon thin film as an inner liner. According to this technique,
Pneumatic by spraying or applying a solution or emulsion of methoxymethylated nylon on the inner surface of a green tire and then vulcanizing the tire, or by spraying or applying a solution or emulsion of methoxymethylated nylon on the inner surface of the tire after vulcanization. Manufactures tires. However, since the tire inner surface rubber and the methoxymethylated nylon are not adhered, when the tire is used under high load, the problem that the methoxymethylated nylon film peels from the tire inner surface rubber, and methoxymethylated There is a problem that the moisture resistance (or water resistance) and heat resistance of the inner liner layer are poor due to the fact that nylon is not crosslinked or cured.

JP-A-5-330307 discloses that the inner surface of a tire is subjected to a halogenation treatment (using a conventionally known chlorination treatment solution, a bromine solution, an iodine solution), and then a methoxymethylated nylon, It is disclosed that a polymer film (film thickness 10 to 200 μm) of copolymerized nylon, a blend of polyurethane and polyvinylidene chloride, or a blend of polyurethane and polyvinylidene fluoride is formed, but its adhesiveness is still insufficient, There is a problem.

Further, Japanese Patent Publication No. 7-53800 discloses that
An N-methoxymethylated nylon crystallized product / rubber obtained by forming a film on the inner surface of a rubber hose using an N-methoxymethylated nylon solution containing an organic acid catalyst, subjecting this to heat treatment to crosslink and then further heat treating to crystallize. A laminate is disclosed, and it is described that the N-methoxymethylated nylon crystallized product has excellent gas permeation resistance.
However, this publication does not disclose the use of such a material for the inner liner layer of a pneumatic tire, and its excellent durability.

Further, Japanese Patent Application Laid-Open No. 7-62229 discloses that
In an N-alkoxyalkylated nylon resin composition and a laminate of the resin composition and a synthetic resin and / or rubber, with respect to the N-alkoxyalkylated nylon resin composition, or with respect to the synthetic resin and / or rubber A technique for blending an oxide of an alkyl metal or an alkaline earth metal, a hydroxide and a metal salt thereof to heat-stabilize an N-alkoxyalkylated nylon resin is disclosed. However, even in this publication, there is no mention of using such a material as a tire liner layer which is required to have durability under severe conditions.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to prevent air permeation, which enables weight reduction of a tire without impairing air pressure retention of the tire, and which is excellent in adhesiveness with a rubber layer and durability. It is to provide a pneumatic tire using a layer.

[0011]

According to the present invention, there is provided a pneumatic tire in which a thin film of an alkoxyalkylated aliphatic polyamide resin composition having a degree of polymerization of 300 to 500 is laminated as an air permeation preventive layer. Provided.

According to the present invention, further, an alkoxyalkylated multi-component polyamide resin having a degree of polymerization of less than 300 is 20% by weight or less, and an alkoxyalkylated aliphatic polyamide resin having a degree of polymerization of 300 to 500 is 80%. Provided is a pneumatic tire including a thin film of an alkoxyalkylated aliphatic polyamide resin composition, which is contained in an amount of not less than wt% as an air permeation preventive layer.

The cross-linked air permeation preventive layer comprising the resin composition according to the present invention has a softening point of 80 ° C. or higher and an air permeability of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg. It is preferable that the Young's modulus is in the range of 1 to 500 MPa below.

The present invention will be described in more detail below. The air-preventing layer of the pneumatic tire according to the present invention is at any position inside the tire, that is, inside or outside the carcass layer, or at any other position such as inside or outside the rubber layer provided adjacent to the carcass layer. Can be placed. In short, the arrangement is not a problem as long as the air pressure inside the tire can be prevented and the air pressure inside the tire can be maintained for a long time.

FIG. 1 is a half sectional view in the meridian direction illustrating a typical example of the arrangement of an air permeation preventive layer of a pneumatic tire.
In FIG. 1, a carcass layer 2 is mounted between a pair of left and right bead cores 1, 1, and an inner liner layer 3 is provided on the inner surface of the tire inside the carcass layer 2. In the present invention, the inner liner layer 3 is composed of a crosslinked body of the liquid composition of the resin. In FIG. 1, 4 indicates a sidewall.

According to the present invention, among the alkoxyalkylated aliphatic polyamides, those having a specific degree of polymerization in the range of 300 to 500 have the physical properties and air permeation required for the inner liner layer. It has been proved that it has durability and withstands durability in actual use of the tire. In addition, while maintaining flexibility, this product is imparted with heat resistance by cross-linking the coating film and can be cured at room temperature, so that it can be applied after vulcanization.

According to the present invention, the degree of polymerization is 30.
As long as 80% by weight or more of the alkoxyalkylated aliphatic polyamide in the range of 0 to 500 is contained, even if it is mixed with an alkoxyalkylated multi-component polyamide resin having a degree of polymerization of less than 300, it has sufficient durability to withstand use. It was also revealed that an inner liner layer having

In the alkoxyalkylated aliphatic polyamide used in the present invention, at least a part of its amide group is an alkoxyalkyl group —R ¹ —O—R ² (wherein R is
¹ is an alkylene group having 1 to 4 carbon atoms, for example, methylene, ethylene, propylene, butylene group, R
² is an alkyl group having 1 to 4 carbon atoms, for example, a methyl, ethyl, propyl or butyl group), and the modified alkoxyalkyl group is, for example, a> NH group of polyamide. Alternatively, it can be introduced by a conventional method such as reacting methanol and paraformaldehyde under an alkaline catalyst.

Examples of polyamides include 6 nylon, 66 nylon, 11 nylon, 610 nylon, 6
A linear polyamide usually called nylon such as 12 nylon, 10 nylon, 6/66 nylon and their co-polymer nylon, or a polymer having a —NH ₂ group in its side chain can be used as a very useful one.

Further, in the present invention, as the multi-component copolymerized polyamide in the alkoxyalkylated multi-component copolymerized polyamide resin having a degree of polymerization of less than 300, which can be used in combination in an amount of up to 20% by weight, a specific copolymerization ratio of 2 is used. Original nylon, such as nylon 6 / nylon 66, and
A ternary or quaternary or higher multi-component copolyamide having a composition of nylon 6 / nylon 66 / nylon 610, nylon 6 / nylon 66 / nylon 12, nylon 6 / nylon 66 / nylon 610 / nylon 12, etc. is used. .

The alkoxyalkylated aliphatic polyamide resin having a degree of polymerization of 300 to 500 according to the present invention and the alkoxyalkylated multi-component polyamide resin having a degree of polymerization of less than 300 used in combination with the same are used as a solvent for coating. The solvent is not particularly limited as long as it is a solvent that dissolves these modified aliphatic polyamide resins, and examples thereof include aliphatic alcohols such as methanol and ethanol and phenol, and cresol. Aromatic alcohols and the like. Further, in these alcohol solvents, water, ethyl acetate, toluene,
Methyl ethyl ketone, benzene, chloroform and the like can also be added. The total concentration of the modified aliphatic polyamide resin and the crosslinking agent is not particularly limited, but is preferably 5
３０30% by weight.

Examples of acid catalysts that can be used in the present invention to crosslink the modified aliphatic polyamide resin include citric acid, tartaric acid, glutaric acid, lactic acid, itaconic acid, azelaic acid, succinic acid, and glycolic acid. , Crotonic acid, hypophosphorous acid, lauric acid, chloric acid,
One or more selected from boric acid, maleic acid, oxalic acid, adipic acid, malonic acid and the like can be mentioned. Aromatic sulfonic acids can also be preferably used. Examples of such aromatic sulfonic acids include paratoluene sulfonic acid,
Orthotoluenesulfonic acid, metatoluenesulfonic acid,
Benzene sulfonic acid, para-cresol sulfonic acid, ortho-cresol sulfonic acid, meta-cresol sulfonic acid,
One or more selected from naphthalene sulfonic acid, dodecylbenzene sulfonic acid and the like can be mentioned. The amount of the acid catalyst used can be conventional, and is preferably 3 to 5 parts by weight with respect to 100 parts by weight of the modified aliphatic polyamide resin.

Examples of the cross-linking agent other than the acid catalyst which can be used for cross-linking the modified aliphatic polyamide resin in the present invention include sulfur simple substance, sulfur-releasing compound (for example, tetramethylthiuram disulfide, mono Folin disulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, dipentamethylene thiuram pentamethylene, dimethyldiphenyl thiuram disulfide), a vulcanization accelerator for rubber (for example, zinc salt of 2-mercaptobenzothiazole, cyclohexylbenzothiazyl)・ Thiazoles such as sulfenamide, tetramethylthiuram disulfide, tetramethylthiuram monosulfide, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfate Thiurams such as I de, dithio acid salts, such as zinc dimethyldithiocarbamate, guanidines such as diphenyl guanidine, thioureas such as 1,3-diphenyl-thiourea) can also be mentioned such. A vulcanization accelerator can be used for the thiurams. The amount of these cross-linking agents used is conventional and not particularly limited, but preferably depends on the type of cross-linking agent used, but is 0.1 to 10 parts by weight, more preferably 0.1 parts by weight per 100 parts by weight of the polymer. ~ 5 parts by weight. In addition to these, peroxides such as dicumyl peroxide (DCP) can also be used.

The cross-linking agent may be an organic halogen donor (eg, chlorosulfonated polyethylene, chloroprene) or an inorganic halide (eg, tin chloride, calcium chloride, iron chloride, chloride) in order to further improve the cross-linking reaction. Aluminum, zinc chloride, calcium fluoride, zinc bromide, etc., for example, 0.1 to 100 parts by weight of the polymer.
5 parts by weight can be used together as a catalyst.

In the present invention, the cross-linking of the modified aliphatic polyamide resin is further carried out by, for example, JP-A-51.
It is also possible to use an alkylphenol formalin resin or an alkylresorcinol formalin resin as described in JP-A-18756.

The method for manufacturing a pneumatic tire according to the present invention will be described with reference to the case where the inner liner layer 3 is arranged inside the carcass layer 2 as shown in FIG.
When the air permeation preventive layer according to the present invention is laminated on the surface (that is, the inner peripheral surface) of the carcass layer of the tire after vulcanizing the green tire according to a conventional method, the degree of polymerization is 300 on the surface of the carcass layer. Or 500 to 500 parts of the alkoxyalkylated aliphatic polyamide resin, or 20% by weight or less of the alkoxyalkylated polycopolymerized polyamide resin having a degree of polymerization of less than 300. By applying, heating and crosslinking, a lightweight pneumatic tire having desired durability can be manufactured.

In the production of the pneumatic tire according to the present invention, the surface of the carcass layer or the rubber layer on the carcass layer can be halogenated by a conventional method. For such halogenation treatment, for example, a general rubber halogenation treatment chlorine solution, bromine solution, iodine solution or the like can be used. As such a solution, an aqueous solution containing chlorine, bromine, or iodine, or a dilute aqueous solution of 12N hydrochloric acid can be used, and further, a -N (X) C (O)-group (in the formula, X represents a halogen). It is preferable to use a diluted solution of the compound containing a) in an organic solvent. Specific examples of such a compound include trichloro-, dichloro-, or monochloro-isocyanuric acid, which can be used as trichloro-isocyanuric acid
Most preferred is the use of a 20 wt% organic solvent solution (eg, a ketone organic solvent solution such as methyl ethyl ketone or an ester organic solvent solution such as ethyl acetate).

The material of the rubber layer on which the inner liner layer according to the present invention is laminated is not particularly limited, and any rubber material conventionally used as a rubber material for tires can be used. Examples of such rubbers include diene rubbers such as NR, IR, BR, and SBR, halogenated butyl rubbers, ethylene-propylene copolymer rubbers, styrene elastomers, and the like, which are mixed with carbon black, process oil, vulcanizing agents, and the like. It can be a rubber composition to which an agent has been added.

The air permeation preventive layer after crosslinking according to the present invention is
The softening point is 80 ° C or higher, preferably 100 ° C or higher, and the air permeability coefficient is 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg or less, preferably 13 × 10 ^-12 cc · cm / cm ² · sec. ·cm
By making the thickness Hg or less, the thickness of the air permeation preventive layer can be made 1/2 or less of the thickness of the conventional air preventive layer.

On the other hand, the Young's modulus is 1 to 500 MPa, preferably 10 to 300 MPa, and the thickness is 0.01 to 1.0 mm, preferably 0.02 to 0.5 mm. Young's modulus is 1 MPa
When it is less than 500 MPa, it is not preferable because handling becomes difficult due to wrinkles during tire molding. On the contrary, when it exceeds 500 MPa, it is not preferable because the tire deformation during running cannot be followed.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically according to examples, but it goes without saying that the present invention is not limited to the following examples.

Example 1 Methoxymethylated nylon EF-30T (polymerization degree: 42
The air permeability coefficient, Young's modulus, elongation, and softening point of the film sample obtained from the 0,6 nylon base solution were measured, and a 15% methanol solution of the methoxymethylated nylon was applied to the inner surface of the tire to a thickness of about 100 μm. Then, after being dried at room temperature for one week, a long-term durability test was performed.

Example 2 Methoxymethylated nylon MF-30 (polymerization degree 390,
6 Nylon base) and the same test as in Example 1.

Example 3 20 parts by weight of methoxymethylated nylon G-550 (average degree of polymerization: 120, 12/6/66 copolymerized nylon base) was added to 80 parts by weight of methoxymethylated nylon EF-30T. The test was conducted in the same manner as in Example 1 using the same thing.

Comparative Example 1 A test was conducted in the same manner as in Example 1 using methoxymethylated nylon G-550.

Comparative Example 2 Methoxymethylated nylon F-30 (degree of polymerization 120, 6
A test was performed in the same manner as in Example 1 using a nylon base).

Comparative Example 3 Using methoxymethylated nylon CM-4000 (average degree of polymerization 120, 6/610/66 nylon base),
The test was performed in the same manner as in Example 1.

70 parts by weight of methoxymethylated nylon EF-30T is added to methoxymethylated nylon G-5.
The test was conducted in the same manner as in Example 1 by using 30 parts by weight of 50.

The method of making the film sample used in the above example is as follows. Preparation of film sample A solution of an alkoxyalkylated aliphatic polyamide resin having a predetermined degree of polymerization and having a composition of each Example and Comparative Example dissolved in a mixed solvent of 70% by weight of methanol and 30% by weight of methyl ethyl ketone in a ratio of 20% by weight, Solution casting method (polymer solution is cast evenly on an endless belt,
A hot air of 0 ° C. was applied to continuously dry the film, and the film was peeled off to form a film). After drying, 130
Cross-linking treatment was carried out by leaving it for 15 minutes in a heater at ℃. (Film: thickness about 100 μm)

The evaluation method used in the above example is as follows.

The air permeation coefficient of the air permeation preventive layer was measured according to JIS K7126 "Plastic Film and Sheet Gas Permeability Test Method (Method A)". Test: The film sample prepared above was used. Test gas: air (N ₂ : O ₂ = 8: 2) Test temperature: 30 ° C

The Young's modulus of the air permeation preventive layer was measured according to JIS K6251 "Tensile test method for vulcanized rubber". Specimen: The film sample prepared above was placed parallel to the flow direction of the solution (the flow direction of the endless belt) with J
I punched it out with IS No. 3 dumbbells. A tangent was drawn on a curve in the initial strain region of the obtained stress-strain curve, and the Young's modulus was determined from the slope of the tangent.

The method for measuring the elongation of the air permeation preventive layer was based on JIS K6251 "Tensile test method for vulcanized rubber". Test: The length between the marked lines at the time of cutting the film sample piece prepared above was measured and calculated by the following formula (1). E _B : Elongation at cutting (%) L ₀ : Gauge distance (mm) L ₁ : Gazing distance at cutting (mm)

Method for measuring the softening point: Using a differential scanning calorimeter (DSC), the temperature is raised at 10 ° C./min and the peak temperature of the endotherm due to the softening point is read. Mechanical testing machine (TM
In A), a compression test was performed with a load of 5 g, and the temperature was read from the inflection point temperature.

Long-term durability test method 165 SR13 steel radial tire (rim 13 × 4
1 / 2-J), air pressure of 200kPa, 1500cc class passenger car, load equivalent to 4 passengers (65kg /
People) and drive 50,000 km on the actual road. After running, remove the tire from the rim, visually observe the inner layer of the tire,
If the liner layer has cracks, wrinkles, peeling, etc., it is judged as unacceptable, and if not, it is judged as "passed". The purpose of this test is to comprehensively evaluate the strength deterioration and adhesion deterioration of the liner layer in an actual vehicle.

Rubber compound for tire carcass Product name Weight part Natural rubber 80.0 SBR1502 20.0 FEF carbon black 50.0 Stearic acid 2.0 Zinc white 3.0 Sulfur yellow 3.0 Vulcanization accelerator (NS) 1.0 Aroma oil 2.0

The evaluation results are shown in the table.

[0048]

[Table 1]

As is clear from the results in the table, the degree of polymerization is 3
When an alkoxyalkylated aliphatic polyamide resin in the range of 00 to 500 is used and the resin has a degree of polymerization of 3
It can be seen that any of those containing 20% by weight or less of the alkoxyalkylated multi-component copolymerized polyamide resin of less than 00 shows remarkable long-term durability.

[0050]

As described above, according to the present invention,
A pneumatic tire having an air permeation preventive layer which is excellent in adhesiveness with a rubber layer and which is excellent in flexibility and durability while achieving good weight retention while maintaining good air pressure retaining property in the tire. be able to.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view in a calf line direction showing a structure of a pneumatic tire of the present invention.

[Explanation of symbols]

 1 ... Bead core 2 ... Carcass 3 ... Inner liner layer 4 ... Sidewall

Claims (3)

[Claims] 1. A pneumatic tire obtained by laminating a thin film of an alkoxyalkylated aliphatic polyamide resin composition having a degree of polymerization of 300 to 500 as an air permeation preventive layer. 2. A compounding amount of 20% by weight or less of an alkoxyalkylated multi-component copolyamide resin having a degree of polymerization of less than 300, and 80% by weight or more of an alkoxyalkylated aliphatic polyamide resin having a degree of polymerization of 300 to 500. A pneumatic tire obtained by laminating a thin film of the alkoxyalkylated aliphatic polyamide resin composition containing in 1) as an air permeation preventive layer. 3. A softening point of 80 ° C. or higher, an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less, and
A pneumatic tire obtained by laminating a thin film of the resin composition according to claim 1 or 2 having an Young's modulus of 1 to 500 MPa as an air permeation preventive layer.