JPH08258506A - Pneumatic tire and manufacture of it - Google Patents

Abstract

PURPOSE: To provide a pneumatic tire and a manufacture of it in which extension of the whole air transmission preventing layer is uniform in inflation without deteriorating the air pressure holding property in a tire, any defective tire is not manufactured by which the joints are opened unlike the conventional method, and controllability is excellent. CONSTITUTION: In a pneumatic tire, a cylindrical thermoplastic film having no joint is used for an air transmission preventing layer, and in a manufacture of a pneumatic tire taking the cylindrical thermoplastic film as the air transmission preventing layer, a single layered or a plural layered cylindrical thermoplastic film is manufactured by extruding and molding thermoplastic resin, and this cylindrical thermoplastic film is supplied on a molding drum by the required amount in molding a green tire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire and a method for manufacturing the same, more specifically, the weight of the tire is reduced without impairing the air pressure retaining property, and the workability of manufacturing the pneumatic tire is improved. In addition, the present invention relates to a pneumatic tire having an air permeation preventive layer such as an inner liner layer having higher uniformity and a method for manufacturing the pneumatic tire.

[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 air permeation preventive layer such as 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 the inner surface rubber and inner liner layer of the carcass layer are corrugated in the gap between the carcass cords after vulcanization of the tire, the inner liner rubber layer is deformed along with the deformation of the carcass layer. Since there is deformation, there is a problem that rolling resistance increases. Therefore, in general, the inner liner layer (halogenated butyl rubber) and the inner surface rubber of the carcass layer are joined together via a rubber sheet called tie rubber having a small hysteresis loss. Therefore, in addition to the thickness of the inner liner layer of halogenated butyl rubber, the thickness of tie rubber is added to make the total layer 1
The thickness exceeds mm (1000 μm), which is one of the causes of increasing the weight of the product tire as a result.

Techniques have been proposed in which various materials are used in place of low gas permeable rubber such as butyl rubber as an air permeation preventive layer such as an inner liner layer of a pneumatic tire. For example, JP-A-6-40207 discloses a low air-permeable layer made of a polyvinylidene chloride film or an ethylene vinyl alcohol copolymer film, and an adhesive layer made of a polyolefin film, an aliphatic polyamide film or a polyurethane film. A thin film is formed by laminating the thin film on the inner surface of the green tire made of unvulcanized rubber so that the adhesive layer contacts the carcass layer,
It has been proposed to vulcanize and mold this green tire to provide an air permeation preventive layer inside the tire.
By using such a multilayer film for the air permeation preventive layer, the thickness of the air permeation preventive layer can be made thinner than before, and the tire weight can be reduced without impairing the air pressure retention. However, in the case of forming an air permeation preventive layer such as an inner liner from such a thermoplastic multilayer film, if the adhesiveness of the joint portion (splice portion) of the multilayer film becomes poor, the liner splice portion of the product may open. There is a risk that the tires will be damaged, and the uniformity of the tire will be small due to the small expansion of the splice during inflation in the tire molding process.
And the vibration and the high-speed durability may decrease when the vehicle is running.

Japanese Unexamined Patent Publication No. 59-93344 discloses an apparatus for forming a tire by attaching a tubular member such as an inner liner to the inside of a green tire. According to this device, the cylindrical inner liner (cylindrical member) is continuously extruded from the extruder, inserted into the green tire placed on the tire stand, and the bladder is inflated to be closely attached to the inside of the green tire. ing. However, if this device is used when a thermoplastic resin film is used as the inner liner material, the tubular shape can be maintained because the thermoplasticity is large when a cylindrical film is continuously extruded downward. However, there is a problem in that the thickness of the film is not accurate, and it is difficult to cut the tubular member (that is, the cylindrical thermoplastic film) inserted into the green tire with a cutter.

[0005]

SUMMARY OF THE INVENTION Therefore, according to the present invention, in the conventional pneumatic tire using the thermoplastic film for the air permeation preventive layer, as described above, the film-bonded joint (splice) is formed in the tire manufacturing process. If the adhesiveness is not sufficient, the joint will open when inflated and a defective tire will be produced, and the elongation of the film joint will be small compared to other parts of the film, so the entire air permeation preventive layer during inflation in the tire molding process. In view of the problems that the tires do not stretch uniformly and the tire uniformity occurs, and the bonding work of the film joint part is complicated, such problems are solved and the air pressure retention in the tire is improved. The entire air permeation preventive layer stretches uniformly during inflation without damaging the Never defective tire is produced, and to provide a good pneumatic tire and a method of manufacturing workability.

[0006]

According to the present invention, there is provided a pneumatic tire using a cylindrical thermoplastic film having no joint portion as an air permeation preventive layer.

According to the present invention, in producing a pneumatic tire having an air permeation preventive layer of a cylindrical thermoplastic film having no joint portion, a thermoplastic resin is extruded to form a single-layer or multi-layer cylinder. It manufactures Jo of thermoplastic film, the cylindrical shaped heat thermoplastic film when the green tire forming method of a pneumatic tire which comprises supplying each necessary amount on the forming drum is provided.

The pneumatic tire according to the present invention and the method for manufacturing the same will be described in more detail below. The air permeation preventive layer of the pneumatic tire according to the present invention can be arranged at any position inside the tire, that is, inside or outside the carcass layer, or at any other position. In short, the object of the present invention can be achieved by preventing the permeation and diffusion of air from the inside of the tire and arranging so that the air pressure inside the tire can be maintained for a long time.

FIG. 1 is a meridional direction half-sectional view 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 air permeation preventive layer 3 is provided on the inner surface of the tire inside the carcass layer 2. The air permeation preventive layer 3 is composed of the cylindrical thermoplastic film in the present invention. In FIG. 1, 4 indicates a sidewall.

In the method of manufacturing a pneumatic tire having an air permeation preventive layer made of a cylindrical thermoplastic film according to the present invention, as shown in FIG. 1, when the air permeation preventive layer 3 is disposed inside the carcass layer 2. As an example, one or more thermoplastic resins having an air permeation preventive action are prepared in advance by general extrusion molding, for example, inflation molding to produce a single-layer or multi-layer cylindrical thermoplastic film.

Next, the extruded single-layer or multi-layered cylindrical thermoplastic film is cut and supplied in a required amount onto a tire forming drum at the time of forming a green tire, and the cylindrical film is fitted into the drum. This cylindrical thermoplastic film can be once wound on a roll or the like and then supplied onto a forming drum at the time of forming a green tire.

Tire members such as carcass, sides, belts, and treads are laminated on the above-mentioned cylindrical thermoplastic film fitted on a molding drum and inflated as usual to produce a green tire, which is vulcanized. A pneumatic tire can be manufactured by integrating.

The material of the rubber layer on which the air permeation preventive 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 rubber include diene rubbers such as NR, IR, BR, SBR, halogenated butyl rubber, ethylene-propylene copolymer rubber,
A rubber composition can be obtained by adding a compounding agent such as carbon black, process oil and a vulcanizing agent to a styrene-based elastomer or the like.

The thermoplastic resin may be any material having an air permeation preventive action. Examples of such a thermoplastic resin include the following thermoplastic resins and any of these or any resin mixture containing them.

Polyamide resin (for example, nylon 6 (N
6), nylon 66 (N66), nylon 46 (N4
6), nylon 11 (N11), nylon 12 (N1
2), nylon 610 (N610), nylon 612
(N612), nylon 6/66 copolymer (N6 / 6
6), nylon 6/66/610 copolymer (N6 / 66
/ 610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP
Copolymer, nylon 66 / PPS copolymer, polyester resin (eg polybutylene terephthalate (PB)
T), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimidic acid / polybutyrate terephthalate Aromatic polyesters such as copolymers), polynitrile resins (for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene) / Butadiene copolymer),
Polymethacrylate resin (for example, polymethylmethacrylate (PMMA), polyethylmethacrylate), polyvinyl resin (for example, vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (E
VOH), polyvinylidene chloride (PDVC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer),
Cellulosic resin (for example, cellulose acetate, cellulose acetate butyrate), fluorine resin (for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer), An imide-based resin (for example, aromatic polyimide (PI)) and the like can be mentioned.
This cylindrical thermoplastic resin film may be a single layer, or
For example, as described in JP-A-6-40207, it is possible to use a multilayer film in which an adhesive layer of a polyolefin-based resin, an aliphatic polyamide-based resin, or a urethane-based resin is provided on both surfaces of the film of the air permeation preventive resin. Heisei 7
Patent Application No. 7- filed by the applicant of the present application filed on Mar. 15, 2015
No. 55929 application, a flat polymer orientation composition comprising one non-breathable thermoplastic resin produced by extrusion stretch molding of a blend of at least two incompatible thermoplastic resins and another thermoplastic resin. It is also possible to use a film formed by dispersing in a resin matrix. Further, the present applicant filed on January 23, 1995, in which these thermoplastic resins contain an arbitrary elastomer component in order to maintain flexibility, the elastomer component serves as a domain, and the resin layer serves as a matrix. Application for Japanese Patent Application No. 7-8
The blend of the 394 application can also be extruded and used as a film.

The cylindrical thermoplastic film forming the air permeation preventive layer of the pneumatic tire according to the present invention has an air permeability of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less, preferably 5 or less. × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less, Young's modulus is 1 to 500 MPa, preferably 10 to 300 MP
a and the film thickness is 0.02-1.0 mm,
It is preferably 0.05 to 0.5 mm. Air permeability is 2
If it exceeds 5 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg, it is not preferable for reducing the weight of the pneumatic tire. On the other hand, if the Young's modulus is too low, the workability is deteriorated due to wrinkles during tire molding, and if it is too high, the tire deformation cannot be followed during running, which is not preferable.

In the present invention, a single-layer or multi-layer cylindrical film preformed by inflation or the like is used, and as described above, a conventional splice part (bonding part of films).
Due to the presence of the above, the difference in modulus between the splice portion (resultingly, two films are overlapped) and the other portion is large, so that the tire is unevenly stretched at the time of inflation and the tire is inferior in uniformity. The modulus difference is, for example, in a butyl rubber liner, a spliced part (Young's modulus of about 10 MPa) and a non-spliced part (Young's modulus of about 5 MPa / cm).
The difference with ² ) is relatively small at 5 MPa, but for example, in the case of a blended resin film of nylon 6 resin and olefin resin (weight ratio: 60/40), the splice part (about 400 MPa)
Difference between the non-spliced part (about 200MPa) is 200MPa
It also becomes.

Further, when the cylindrical film is used as the air permeation preventive layer as in the present invention, the work is very simple because it is simply fitted into the forming drum at the time of forming the tire. As in the past, winding the film and pasting the bonded portion is inferior in workability, and the above-described problem of defective bonding may occur. Alternatively, if the splice has wrinkles, air leaks through them and the intended purpose cannot be achieved.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited to the following examples.

Example 1 Two layers of polypropylene resin layer (thickness: 0.02 mm each)
A polyvinylidene chloride resin layer (thickness: 0.05 mm) was laminated between the three-layer film, and the diameter of the three-layer film was measured by a multi-layer inflation device using two general 40 mmφ resin extruders.
It was processed into a cylindrical film having a thickness of 45 mm and a thickness of 0.09 mm and wound up. Length 36 from this rolled up cylindrical film
0 mm was cut out and fitted into a tire forming drum, and tire members such as a carcass, a side, a belt and a tread were laminated on this cylindrical film and inflated to produce a green tire. Here, as the polyvinylidene chloride, Dow Chemical F-313 was used, and as the polypropylene resin, PER R110E manufactured by Tokuyama Corporation was used. Next, this green tire was vulcanized at 185 ° C. for 15 minutes at a pressure of 2.3 MPa to finish a tire having a tire size of 165SR13.
When molding a green tire, the time for setting the cylindrical film on the molding drum, the uniformity of the manufactured pneumatic tire, and the air leak performance of the obtained tire were measured. The results are shown in Table I.

Uniformity test method The uniformity (uniformity) is represented by the RFV value according to JASO C607-87 "Uniformity test method for automobile tires". Tire Air Leakage Performance Test Method 165SR13 Steel Radial Tire (Rim 13
X41 / 2-J), initial pressure of 200 kPa, no load condition, room temperature of 21 ° C, left for 3 months, measurement interval 4
The pressure was measured daily. As the measured pressure Pt, the initial pressure Po, and the elapsed days t, the α value is obtained by regressing the function: Pt / Po = exp (−αt). Using the obtained α, t = 30
Is substituted into the following equation to obtain β = [1−exp (−αt)] × 100 β value. This β value is the rate of pressure drop per month (% /
Month).

Comparative Example 1 The same three-layer film as that prepared in Example 1, which was cut and processed into a strip having a width of 360 mm and a thickness of 0.09 mm, was wound around a tire building drum, and the splice portion is usually used. Bonding was performed with a phenol resin adhesive, and then a tire was prepared in the same manner as in Example 1. The same test as in Example 1 was performed on the obtained tire. Further, the liner winding step time is shown in Table I, together with the time when the strip-shaped film is wound at the time of molding the green tire, the splice portion is joined with the adhesive and set on the molding drum.

Table I ─────────────────────────────────── Liner Liner winding Uniformity ^{* 2} Tire air pressure Shape Process time ^{* 1} Leakage performance ─────────────────────────────────── Implemented cylindrical 70 93 100 Example 1 No splice ─────────────────────────────────── Comparison of strips 100 100 100 100 Example 1 With splicing splice ─ ────────────────────────────────── * 1: The process when the process time of Comparative Example 1 is 100. Time (expressed as an index) * 2: The RFV average value of n = 20 lines was expressed as an index

Examples 2 and 3 Compounds shown in Table II, that is, a resin, a rubber material, and a crosslinking compound necessary for dynamic crosslinking were mixed in a twin-screw kneading extruder, extruded in a strand shape, and cooled. After pelletizing using a pelletizing machine, melt extrusion / inflation molding was carried out using a usual 40 mm extruder for uniaxial resin to produce a cylindrical film. The resin material is a thermoplastic resin material in which the resin layer serves as a matrix, the rubber layer serves as a domain (dispersion layer), and is crosslinked.
After that, a tire was prepared in the same manner as in Example 1 and subjected to the test. The results are shown in Table III.

Table II ─────────────────────────── Example 3 Example 4 ───────────── ─────────────── N6 ^{* 1} 50 MXD6 ^{* 2} 50 Br-IPMS ^{* 3} 50 50 GPF ^{* 4} 30 30 Paraffinic process oil 10 10 Zinc white 0.25 0.25 Stearine Acid 11 Zinc stearate 0.5 0.5 ─────────────────────────── * 1: Toray Industries, Ltd. Amilan CM1041 * 2: Reny 6002 manufactured by Mitsubishi Gas Chemical Co., Ltd. * 3: Bromide of paramethylstyrene-isobutylene copolymer, XP-50 90-10, manufactured by Exxon Chemical Co., Ltd. * 4: Carbon black, manufactured by Tokai Carbon Co., Shist V

Table III ─────────────────────────────────── Liner shape Liner winding Uniformity ^{* 2} Air Permeation prevention Process time ^{* 1} Action ^{* 3} ──────────────────────────────────── Example Cylindrical 70 90 100 2 No splice ─────────────────────────────────── Example Cylindrical 71 90 100 3 No splice ─ ────────────────────────────────── Comparative example Bonding strips 100 100 100 1 With splice ──── ─────────────────────────────── * 1: Process time when the process time of Comparative Example 2 is 100 (index Display) * 2: n = 2 Showing the RFV average value of the at index * 3: shows a pressure measurement value measured by the tire air leakage performance test

[0027]

As described above, according to the present invention,
By reducing the weight of the tire without impairing the air pressure retention in the tire, and by using a cylindrical thermoplastic film as an air permeation preventive layer, it is possible to improve the quality and reliability of the pneumatic tire (that is, the pneumatic tire). Since there is no joint of the permeation preventive layer film, the expansion during inflation in the tire molding process is constant and the uniformity of the air permeation preventive layer is improved, and there is no possibility that the film joint will open when inflated and produce a defective product), and The workability of manufacturing a pneumatic tire can be improved (the film bonding operation is complicated, while the cylindrical material can be easily inserted into the green tire).

[Brief description of drawings]

FIG. 1 is a meridional direction half-sectional view showing a structure of an inner liner portion of a pneumatic tire of the present invention.

[Explanation of symbols]

 1 ... Bead core 2 ... Carcass layer 3 ... Air permeation preventive layer 4 ... Side wall

Claims (4)

[Claims] 1. A pneumatic tire using a cylindrical thermoplastic film having no joint portion as an air permeation preventive layer. 2. A single-layer or multi-layered cylindrical thermoplastic resin is produced by extruding a thermoplastic resin for producing a pneumatic tire having a non-bonded cylindrical thermoplastic film as an air permeation preventive layer. A method for producing a pneumatic tire, which comprises producing a film, and supplying the cylindrical thermoplastic film onto a forming drum in a required amount each time a green tire is formed. 3. The method for producing a pneumatic tire according to claim 2, wherein the extruded cylindrical thermoplastic film is once wound and then supplied onto a forming drum at the time of forming a green tire. 4. The green tire prepared by laminating a tire member on a cylindrical thermoplastic film supplied onto a drum and inflating the tire, and vulcanizing the green tire to integrate the green tire. Manufacturing method for pneumatic tires.