JP3159886B2 - Pneumatic tire and manufacturing method thereof - Google Patents

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, and more particularly, to reducing the weight of the tire without impairing the air pressure retention and improving the workability of manufacturing the pneumatic tire. The present invention relates to a pneumatic tire having an air permeation preventing layer such as an inner liner layer having higher uniformity, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Reduction of the fuel consumption rate is one of the major technical issues in automobiles, and as a measure against this, there is an increasing demand for lighter pneumatic tires. By the way, on the inner surface of the pneumatic tire, an air permeation preventing layer such as an inner liner layer made of rubber having low gas permeability such as halogenated butyl rubber is provided in order to keep the tire air pressure constant. However, since the halogenated butyl rubber has a large hysteresis loss, if the inner rubber of the carcass layer and the inner liner layer are wavy in the gap between the carcass cords after vulcanization of the tire, the inner liner rubber layer is deformed together with the deformation of the carcass layer. Is deformed, so that 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 bonded to each other via a rubber sheet called a 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, and 1
The thickness of the tire exceeds 1000 mm (1000 μm), which is one of the causes of increasing the weight of the product tire.

A technique has been proposed in which various materials are used in place of a low gas permeable rubber such as butyl rubber as an air permeation preventing layer such as an inner liner layer of a pneumatic tire. For example, JP-A-6-40207 discloses a low-ventilation layer made of a polyvinylidene chloride-based film or an ethylene vinyl alcohol copolymer film, and an adhesive layer made of a polyolefin-based film, an aliphatic polyamide-based film, or a polyurethane-based film. After laminating and forming a thin film, this thin film is laminated on the inner surface of the green tire made of unvulcanized rubber so that the adhesive layer is in contact with the carcass layer,
It has been proposed to provide an air permeation preventing layer inside the tire by vulcanizing the green tire.
By using such a multilayer film for the air permeation prevention layer, the thickness of the air permeation prevention layer can be made smaller than before, and the tire weight can be reduced without impairing the air pressure retention. However, when an air permeation preventing layer such as an inner liner is formed from such a thermoplastic multilayer film, if the adhesiveness of the bonding portion (splice portion) of the multilayer film becomes poor, the liner splice portion of the product is opened. And the uniformity of the tire due to the small elongation of the splice during inflation in the tire molding process
And there is a possibility that vibrations may occur or the high-speed durability may decrease during running of the vehicle.

JP-A-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, a cylindrical inner liner (cylindrical member) is continuously extruded from an extruder, and is inserted into a green tire placed on a tire mounting table to inflate a bladder and adhere to the inside of the green tire. ing. However, when this apparatus is used when a thermoplastic resin film is used as an inner liner material, when a cylindrical film is continuously extruded downward, the cylindrical shape can be maintained due to high thermoplasticity. In addition, there is a problem that the accuracy of the thickness of the film is not obtained, and it is difficult to cut the cylindrical member (that is, the cylindrical thermoplastic film) inserted into the green tire by the cutter.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a conventional pneumatic tire using a thermoplastic film for an air permeation preventing layer, as described above, in a film bonding joint (splice) in a tire manufacturing process. If the adhesiveness is not sufficient, the joints will open at the time of inflation and defective tires will be produced, and the elongation of the film joints will be smaller than other parts of the film, so the entire air permeation prevention layer will be used at the time of inflation in the tire molding process In consideration of the problem that the uniformity of the tire does not stretch uniformly and the problem that the bonding work of the film joint is complicated, the problem is solved and the air pressure retention in the tire is solved. The entire air permeation prevention layer has uniform elongation during inflation without damaging 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 preventing layer.

According to the present invention, the pneumatic tire includes:
In producing a pneumatic tire using a cylindrical thermoplastic film having no joint portion as an air permeation preventing layer, the air permeability is 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg and the Young's modulus is 1 A single-layer or multiple-layer cylindrical thermoplastic film is manufactured by extruding a thermoplastic resin of up to 500 MPa, and this cylindrical thermoplastic film is supplied onto a forming drum in a required amount at the time of green tire molding. Can be produced by a method for producing a pneumatic tire comprising:

Hereinafter, the pneumatic tire according to the present invention and the method for manufacturing the same will be described in more detail. The air permeation prevention layer of the pneumatic tire according to the present invention can be arranged at an arbitrary position inside the tire, that is, inside or outside the carcass layer, or at another position. In short, the object of the present invention can be achieved by arranging the tire so as to prevent the transmission and diffusion of air from the inside of the tire and maintain the air pressure inside the tire for a long period of time.

FIG. 1 is a half sectional view in the meridian direction illustrating a typical example of the arrangement of an air permeation preventing 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 preventing layer 3 is provided on the inner surface of the tire inside the carcass layer 2. The air permeation prevention layer 3 is composed of the cylindrical thermoplastic film in the present invention. In FIG. 1, reference numeral 4 denotes a sidewall.

In the method for manufacturing a pneumatic tire having an air permeation preventing layer made of a cylindrical thermoplastic film according to the present invention, as shown in FIG. 1, an air permeation preventing layer 3 is arranged inside a carcass layer 2. To explain one example, one or more thermoplastic resins having an air permeation-preventing action are produced 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-layer cylindrical thermoplastic film is cut and supplied by a required amount onto a tire forming drum at the time of forming a green tire, and the cylindrical film is put on the drum. After this cylindrical thermoplastic film is once wound up on a roll or the like, it can be supplied onto a forming drum when forming a green tire.

A tire member such as a carcass, a side, a belt, a tread, etc. is laminated on the cylindrical thermoplastic film fitted on a forming 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 preventing 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, SBR, halogenated butyl rubber, ethylene-propylene copolymer rubber,
A rubber composition can be obtained by adding compounding agents such as carbon black, process oil, and vulcanizing agent to a styrene-based elastomer or the like.

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

A 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 (for example, polybutylene terephthalate (PB
T), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylenediimidic acid / polybutylate terephthalate Aromatic polyesters such as copolymers), polynitrile resins (eg, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / Butadiene copolymer),
Polymethacrylate resins (eg, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl resins (eg, 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 resins (eg, cellulose acetate, cellulose acetate butyrate), fluororesins (eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer), An imide-based resin (for example, aromatic polyimide (PI)) can be given.
This cylindrical thermoplastic resin film may be a single layer, or
For example, as described in JP-A-6-40207, a multilayer film in which an adhesive layer of a polyolefin-based, aliphatic polyamide-based, or urethane-based resin is provided on both surfaces of the film of the air permeation prevention resin, Heisei 7
Patent Application No. 7- filed by the applicant of the present invention filed on March 15, 2016
As described in US Pat. No. 55,929, a flat polymer orientation consisting of one impermeable thermoplastic resin made by extrusion-stretching a blend of at least two incompatible thermoplastic resins is used to convert another thermoplastic polymer orientation to another thermoplastic resin. A film dispersed in a resin matrix can also be used. Further, these thermoplastic resins contain an arbitrary elastomer component in order to maintain flexibility, the elastomer component is used as a domain, and the resin layer is used as a matrix. 7-8
The blend of the '394 application can also be extruded as a film and used.

The cylindrical thermoplastic film constituting the air permeation preventing 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 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg. × 10 ^-12 cc · cm / cm ² · sec · cmHg or less and Young's modulus is 1 to 500 MPa, preferably 10 to 300 MPa
a, and the thickness of the film is 0.02-1.0 mm,
Preferably it is 0.05 to 0.5 mm. Air permeability 2
If it exceeds 5 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg, it is not preferable in terms of reducing the weight of the pneumatic tire. On the other hand, if the Young's modulus is too low, workability is reduced due to wrinkles and the like during tire molding, and if it is too high, it is not preferable because the tire cannot follow tire deformation during running.

According to the present invention, as described above, a conventional splice portion (joining portion of a film) is formed by using a single-layer or multi-layer cylindrical film formed in advance by inflation or the like.
Due to the presence of, there is a large difference in modulus between the splice portion (as a result, two films are overlapped) and other portions, so that the tire is unevenly stretched at the time of inflation, resulting in a tire having poor uniformity. For example, the difference in modulus between a splice part (about 10 MPa in Young's modulus) and a non-splice part (about 5 MPa / cm in Young's modulus) in a butyl rubber liner
The difference from ² ) is relatively small at 5 MPa. For example, in a blend resin film of a nylon 6 resin and an olefin resin (weight ratio: 60/40), a splice portion (about 400 MPa) is used.
And the difference between the non-spliced part (about 200MPa) is 200MPa
Also.

Further, when a cylindrical film is used as an air permeation preventing layer as in the present invention, the operation is very simple, since the cylinder film is simply fitted on a forming drum at the time of forming a tire. As in the past, winding the film and attaching the bonding portion is inferior in workability, and may cause the above-described problem of poor bonding. Alternatively, when wrinkles occur in the splice, air leaks through the splices, and the intended purpose cannot be achieved.

[0019]

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

Example 1 Two layers of polypropylene resin (thickness: 0.02 mm each)
A three-layer film in which a polyvinylidene chloride resin layer (thickness: 0.05 mm) is interposed between the three-layer film is formed by a multi-layer inflation apparatus 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 was wound up. From the rolled cylindrical film, length 36
A 0 mm piece was cut out, fitted to a drum for tire molding, and tire members such as a carcass, side, belt, and tread were laminated on the cylindrical film and inflated to produce a green tire. The polyvinylidene chloride used herein was Dow Chemical F-313, and the polypropylene resin used was PER R110E manufactured by Tokuyama Corporation. Next, the green tire was vulcanized at 185 ° C. for 15 minutes at a pressure of 2.3 MPa to complete a tire having a tire size of 165SR13.
The time for setting the cylindrical film on the forming drum when forming a green tire, the uniformity of the manufactured pneumatic tire, and the air leakage performance of the obtained tire were measured. The results are shown in Table I.

Uniformity test method The uniformity is represented by an RFV value according to JASO C607-87 "Automobile tire uniformity test method". Tire Air Leakage Performance Test Method 165SR13 Steel Radial Tire (Rim 13
× 41 / 2-J), leave at room temperature of 21 ° C. for 3 months under initial pressure of 200 kPa and no load, and measure at 4
The pressure was measured daily. As the measured pressure Pt, the initial pressure Po, and the number of elapsed days t, an α value is obtained by regressing on the function: Pt / Po = exp (−αt). Using the obtained α, t = 30
Into the following equation to obtain β = [1−exp (−αt)] × 100 β value. This β value is calculated as the pressure drop rate per month (% /
Month).

COMPARATIVE EXAMPLE 1 The same three-layer film as that prepared in Example 1 was cut and processed into a strip having a width of 360 mm and a thickness of 0.09 mm, and was wound around a tire forming drum, and a splice portion was usually used. After joining with a phenolic resin-based adhesive, a tire was manufactured in the same manner as in Example 1. The same test as in Example 1 was performed on the obtained tire. Table I shows the liner winding process time in which a green film is formed by winding a belt-like film, bonding a splice portion with an adhesive, and setting the same on a forming drum.

Table I ─────────────────────────────────── Liner Liner winding Uniformity ^{* 2} Tire air Shape Process time ^{* 1} Leakage performance ─────────────────────────────────── Implementation Cylindrical 70 93 100 Example 1 No splice ───────────────────────────────────Comparison belt 100 100 100 Example 1 With splice ─ ────────────────────────────────── * 1: Process when the process time of Comparative Example 1 is set to 100 Time (exponential display) * 2: RFV average value of n = 20 lines was expressed by exponent

Examples 2 and 3 The formulations shown in Table II, ie, the resin, rubber material and the crosslinking compound necessary for dynamic crosslinking were mixed in a twin-screw kneading extruder, extruded into strands, cooled, and cooled. After pelletizing using a pelletizer, melt extrusion / inflation molding was performed using a normal 40 mm uniaxial resin extruder 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.
Thereafter, a tire was manufactured in the same manner as in Example 1 and subjected to a 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 Paraffin-based process oil 10 10 Zinc white 0.25 0.25 Stearin Acid 11 1 Zinc stearate 0.5 0.5 ─────────────────────────── * 1: Amilan CM1041 * manufactured by Toray Industries, Inc. 2: Reny 6002 manufactured by Mitsubishi Gas Chemical Company * 3: Brominated paramethylstyrene / isobutylene copolymer, XP-50 90-10, manufactured by Exxon Chemical Company * 4: Carbon black, manufactured by Tokai Carbon Co., Ltd., Seast V

Table IIIの Liner shape Liner winding Uniformity ^{* 2} Air Permeation prevention process time ^{* 1} action ^{* 3} ─────────────────────────────────── Example Cylindrical 70 90 100 2 without splice ─────────────────────────────────── Example cylindrical 71 90 100 3 without splice ─比較 Comparative example Joining a strip 100 100 100 1 With splice ──── * * 1: The process time (index) when the process time of Comparative Example 2 is set to 100 * 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,
The weight and weight of the tire can be reduced without impairing the air pressure retention in the tire, and the quality and reliability of the pneumatic tire can be improved by using a cylindrical thermoplastic film with an air permeation preventing layer. Since there is no joint of the anti-permeation layer film, the elongation at the time of inflation in the tire molding process is constant, the uniformity of the air permeation prevention layer is improved, and there is no possibility that the film joint will open at the time of inflation to cause defective products), and The manufacturing workability of the pneumatic tire can be improved (the laminating operation of the film is complicated, but the insertion of the cylindrical material into the green tire is easy).

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bead core 2: Carcass layer 3: Air permeation prevention layer 4: Side wall

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-93344 (JP, A) JP-A-6-40207 (JP, A) JP-A-5-278409 (JP, A) JP-A-4- 77243 (JP, A) JP-A-8-259741 (JP, A) JP-A-8-244402 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 5 / 00,5 / 14 B29D 30/30

Claims (4)

(57) [Claims] In producing a pneumatic tire using a cylindrical thermoplastic film having no joint portion as an air permeation preventing layer, the air permeability is 25 × 10 ⁻¹² cc · cm / cm ² · se.
c ・ A single-layer or multiple-layer cylindrical thermoplastic film is manufactured by extruding a thermoplastic resin having a Young's modulus of 1 to 500 MPa with a cmHg or less, and this cylindrical thermoplastic film is molded during green tire molding. A method for manufacturing a pneumatic tire, comprising supplying a required amount on a drum. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein the extruded cylindrical thermoplastic film is wound once and then supplied onto a forming drum at the time of forming a green tire. 3. The green tire produced by laminating a tire member on a cylindrical thermoplastic film supplied onto a drum, vulcanizing and inflating a green tire produced by inflation. Of manufacturing pneumatic tires. 4. A pneumatic tire produced by the method according to claim 1, wherein a cylindrical thermoplastic film having no joint portion is used for an air permeation preventing layer.