JP2002283808A - Air tire and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air tire and its manufacturing method which improves its engagement with a rim despite a layer for preventing air permeation being formed by a cylindrical thermoplastic resin film with no connection. SOLUTION: For an air tire whose layer for preventing air permeation is formed by the cylindrical thermoplastic resin film 3 with no connection, a width direction end 3a of the thermoplastic resin film 3 is arranged within a space M which is 1 mm-30 mm from a bead toe 4 to a side 5 direction along the inner surface of the tire. The cylindrical thermoplastic resin film 3 is arranged on the inner surface of a green tire made of unvulcanized rubber, the width direction end 3a of the thermoplastic resin film 3 is arranged within the space M which is 1 mm-30 mm from the bed toe 4 to the side 5 direction along the inner surface of the green tire, and either dry gas or inert gas inside the green tire for vulcanization whose moisture percentage is 10% or less, oxygen content percentage is 10% or less, and temperature is 170-250 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having improved fitting with a rim and a method for manufacturing the same.

[0002]

2. Description of the Related Art An air permeation prevention layer (inner liner layer) is provided on the inner surface of a pneumatic tire to prevent air leakage and maintain a constant tire pressure.

Conventionally, a low air-permeable halogenated butyl rubber has been used as the air-permeation preventing layer.
Since this halogenated butyl rubber has a characteristic of poor affinity with other rubbers and low adhesiveness, when forming an air permeation prevention layer, the air permeation prevention layer is inevitably thick because a rubber sheet called a tie rubber is interposed. However, there is a problem that the weight of the tire increases.

In recent years, in order to reduce the weight of the tire, it has been proposed that the air permeation preventing layer be formed of a resin film having low air permeability, particularly a cylindrical thermoplastic resin film having no joint. For example, JP-A-10-29
248). However, when the air permeation prevention layer is formed with the cylindrical thermoplastic resin film as described above, the cylindrical thermoplastic resin film extends from the inner surface of the tire to the bead heel through the bead base to sufficiently prevent air leakage. Because the thermoplastic resin film has a lower coefficient of friction than rubber, the bead base is easy to slip against the rim when assembled to the rim, and the fitting property with the rim is poor. was there.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the fitting with a rim despite forming an air permeation preventing layer with a cylindrical thermoplastic resin film having no joint. An object of the present invention is to provide a pneumatic tire and a method for manufacturing the same.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a pneumatic tire in which an air-permeation preventing layer is formed of a cylindrical thermoplastic resin film having no joint portion, wherein a width direction end of the thermoplastic resin film is formed by a bead toe. It is arranged between 1 mm and 30 mm in the side portion direction along the tire inner surface.

Between 1 mm and 30 mm in the side direction from the bead toe along the inner surface of the tire, a portion where the vicinity of the bead toe is crushed and comes into contact with the rim when the tire is assembled into a rim and filled with air. is there. In the present invention, since the width direction end of the cylindrical thermoplastic resin film having no joint portion is disposed at this portion as described above, the entire inner surface of the tire is uniformly covered with the thermoplastic resin film. There will be no air leaks in the vehicle. Further, in the present invention, the width direction terminal of the thermoplastic resin film is disposed at this location as described above, and the width direction of the thermoplastic resin film extends from the inner surface of the tire to the bead heel through the bead base portion as in the related art. Since the bead base portion is not covered with the end portion, the bead base portion does not become easily slippery with respect to the rim when the rim is assembled, so that the fitting property with the rim can be improved.

Further, in the present invention, a cylindrical thermoplastic resin film is arranged as an air permeation preventing layer on the inner surface of a green tire made of unvulcanized rubber, and a terminal in the width direction of the thermoplastic resin film is from a bead toe. It is positioned between 1 mm and 30 mm in the side direction along the inner surface of the green tire. Then, in the mold, the moisture content is 10% or less, the oxygen content is 10% or less, and the temperature is 170-250 ° C. The present invention provides a method for producing a pneumatic tire, which comprises introducing a dry gas or an inert gas to perform vulcanization.

Since the width direction end of the cylindrical thermoplastic resin film is positioned between 1 mm and 30 mm along the inner surface of the green tire from the bead to the side portion, the vulcanization is performed between 1 mm and 30 mm. At this time, since the part of the mold is in contact with the part (the mold grips the bead near this part and fixes the green tire in the mold), the entire inner surface of the green tire is uniformly heated in the mold. Because it is covered with the thermoplastic resin film, the dry gas or the inert gas as the heat medium can enter the tire and cause poor adhesion between the thermoplastic resin film and the tire inner rubber and deterioration of the tire member such as the carcass layer. Absent. In addition, since a dry gas or an inert gas having a moisture content of 10% or less, an oxygen content of 10% or less, and a temperature of 170 to 250 ° C. is used as a heat medium, a cylindrical thermoplastic resin film is formed of a water such as nylon. Even if it is made of a resin which is liable to undergo decomposition and oxidative deterioration, deterioration of the thermoplastic resin film by the heat medium does not occur. And according to this manufacturing method, a pneumatic tire with improved fitting with the rim can be easily obtained.

[0010]

FIG. 1 is a half-sectional view in the meridian direction of an example of a pneumatic tire according to the present invention. In FIG.
A carcass layer 2 is mounted between a pair of left and right bead cores 1, 1, and a cylindrical thermoplastic resin film 3 is provided as an air permeation preventing layer on the inner surface of the tire inside the carcass layer 2. Width direction end 3a of thermoplastic resin film 3
Are arranged at a distance M between 1 mm and 30 mm in the direction from the bead toe 4 to the side portion 5 along the tire inner surface. 1m
If it is less than m, it will be inserted between the rim and the rim due to deformation of the rubber, and the fitting property with the rim will be deteriorated. On the other hand, if it is more than 30 mm, it will come out above the low bead filler and cause air leakage. In FIG. 1, reference numeral 6 denotes a bead base, and 7 denotes a bead base.
Indicates a bead heel, respectively.

In the present invention, the cylindrical thermoplastic resin film 3 constituting the air permeation preventing layer has an air permeation coefficient of 2
5 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less, preferably 5 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less and a Young's modulus of 1 to 500 MPa, preferably 10 to 300 MPa
a. Air permeation coefficient of 25 × 10 ^-12 cc · cm
/ Cm ² · sec · cmHg, the thickness of the air permeation prevention layer must be increased to maintain the tire air pressure.
This defeats the purpose of reducing the weight of tires. Further, if the Young's modulus of the film is less than 1 MPa, wrinkles and the like are generated at the time of tire molding, and the moldability is deteriorated. If it exceeds 500 MPa, durability is problematic, which is not preferable.

Examples of the thermoplastic resin of the thermoplastic resin film 3 include polyamide resins (for example, nylon 6 (N6), nylon 66 (N66), nylon 46).
(N46), nylon 11 (N11), nylon 12
(N12), nylon 610 (N610), nylon 6
12 (N612), nylon 6/66 copolymer (N6 /
66), nylon 6/66/610 copolymer (N6 / 6
6/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / P
P copolymer, nylon 66 / PPS copolymer), and N-alkoxyalkylated products thereof, for example, methoxymethylated 6-nylon, methoxymethylated 6-610-nylon, methoxymethylated 612-nylon, Polyester resin (for example, polybutylene terephthalate (PBT), polyethylene terephthalate (P
ET), polyethylene isophthalate (PE10), P
ET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylenediimidic acid / polybutylate terephthalate copolymer),
Polynitrile resins (for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile /
Styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resin (for example, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl resin (for example, vinyl acetate, polyvinyl alcohol) PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDVC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile Copolymer), cellulosic resin (eg, cellulose acetate, cellulose acetate butyrate), fluororesin (eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PC)
TFE), tetrafluoroethylene / ethylene copolymer), imide resin (for example, aromatic polyimide (P
I) and the like, and two or more kinds may be used.

To produce the thermoplastic resin film 3,
These resins may be extruded into a cylindrical shape by an ordinary method using an ordinary cylindrical film extruder.

Further, as the thermoplastic resin film 3,
A film obtained by blending an elastomer with the above thermoplastic resin may be used.

As the elastomer component that can be blended with the thermoplastic resin, the type and composition of the elastomer component can be selected as long as the composition has the above-mentioned air permeability coefficient and Young's modulus when blended with the thermoplastic resin component. The amount is not particularly limited. Examples of such an elastomer include the following.

Diene rubber and its hydrogenated product (for example, N
R, IR, epoxidized natural rubber, SBR, BR (high-dis BR and low-cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin-based rubber (eg, ethylene propylene rubber (EPDM, EPM), maleic acid) Modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer), acrylic rubber (ACM), ionomer, halogen-containing rubber (for example, Br-IIR, CI-IIR, isobutylene para) Brominated methylstyrene copolymer (Br-IPM)
S), CR, hydrin rubber (CHR.CHC), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid-modified chlorinated polyethylene (M-
CM)), silicone rubber (eg, methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg, polysulfide rubber), fluoro rubber (eg, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber) , Tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), and thermoplastic elastomers (for example, styrene-based elastomers, olefin-based elastomers, ester-based elastomers, urethane-based elastomers, and polyamide-based elastomers). And two or more of them may be used.

In order to produce a cylindrical thermoplastic resin film 3 composed of a blend of a thermoplastic resin and an elastomer, a thermoplastic resin component and an elastomer component (unvulcanized product in the case of rubber) are biaxially kneaded in advance. Melt and knead with an extruder, etc.
The elastomer component may be dispersed in a thermoplastic resin forming a continuous phase, and then extruded into a cylindrical shape by a conventional method.

In order to vulcanize the elastomer component, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer component. The various additives (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading, but are preferably mixed in advance before the kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer component is not particularly limited, and a screw extruder,
Examples include a kneader, a Banbury mixer, and a twin screw extruder. Among them, a twin-screw kneading extruder is preferably used for kneading the thermoplastic resin and the elastomer component and for dynamic vulcanization of the elastomer component. Further, two or more types of kneaders may be used to knead sequentially. As conditions for melt kneading,
The temperature may be at least the temperature at which the thermoplastic resin melts.
Further, the shear rate during kneading is preferably 1000 to 7500 sec ^-1 . The whole kneading time is from 30 seconds to 10
If a vulcanizing agent is added, the vulcanization time after the addition is preferably from 15 seconds to 5 minutes. The kneaded material produced by the above method is then formed into a cylindrical film by extrusion. The thermoplastic resin film 3 thus obtained has a structure in which the elastomer component (B) is dispersed as a discontinuous phase in the matrix of the thermoplastic resin (A).

When the compatibility between the thermoplastic resin and the elastomer component is different, it is preferable to add a suitable compatibilizer as the third component. By mixing the compatibilizer into the system, the interfacial tension between the thermoplastic resin and the elastomer component is reduced, and as a result, the rubber particles forming the dispersion layer become finer, so that the properties of both components are more improved. It will be effectively expressed. Such a compatibilizer is generally a copolymer having a structure of both or one of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen group, an amino group capable of reacting with the thermoplastic resin or the elastomer component. It can have a copolymerized structure having a group, an oxazoline group, a hydroxyl group and the like. These may be selected according to the type of the thermoplastic resin and the elastomer component to be mixed.
Ethylene / butylene block copolymer (SEBS) and its maleic acid modified product, EPDM: EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid modified product, styrene / maleic acid copolymer,
Reactive phenoxine and the like can be mentioned. The amount of such a compatibilizer is not particularly limited, but is preferably a polymer component (total of a thermoplastic resin and an elastomer component).
0.5 to 10 parts by weight per 100 parts by weight is preferred.

When blending the thermoplastic resin and the elastomer, the composition ratio of the specific thermoplastic resin (A) and the elastomer component (B) is not particularly limited, and the film thickness, air permeability resistance, flexibility and It may be appropriately determined by the balance of the properties, but a preferable range is 10/9 by weight ratio (A) / (B).
0-90 / 10, more preferably 15 / 85-90 / 1
0.

The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time) and the like for dynamically vulcanizing may be determined as appropriate according to the composition of the elastomer component to be added, and are particularly limited. There is no.

As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specifically, examples of the ionic vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, and alkylphenol disulfide. About 4 phr (parts by weight per 100 parts by weight of the rubber component (polymer)) may be used.

The organic peroxide vulcanizing agents include:
Benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide,
Examples thereof include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethylhexane-2,5-di (peroxylbenzoate).
About 1 to 15 phr may be used.

Further, as a phenol resin-based vulcanizing agent, bromide of alkylphenol resin, tin chloride,
A mixed crosslinking system containing a halogen donor such as chloroprene and an alkylphenol resin is exemplified.
About 20 phr may be used.

In addition, zinc white (about 5 phr), magnesium oxide (about 4 phr), litharge (10 to 20 phr)
phr), p-quinonedioxime, p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone,
Poly-p-dinitrosobenzene (about 2 to 10 phr),
Methylene dianiline (about 0.2 to 10 phr) is exemplified.

[0026] If necessary, a vulcanization accelerator may be added. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate, and thiourea, for example, 0.5 to 2 phr. The degree may be used.

Specifically, hexamethylenetetramine or the like is used as the aldehyde / ammonia-based vulcanization accelerator; diphenylguanidine is used as the guadinine-based vulcanization accelerator; dibenzo is used as the thiazole-based vulcanization accelerator. Thiazyl disulfide (DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt and the like; sulfenamide vulcanization accelerators include cyclohexylbenzothiazylsulfenamide (CBS);
N-oxydiethylenebenzothiazyl-2-sulfenamide, Nt-butyl-2-benzothiazolesulfenamide, 2- (thymolporinyldithio) benzothiazole and the like; , Tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram tetrasulfide, etc .; as dithioate-based vulcanization accelerators, Zn-dimethyldithiocarbamate; Zn-
Thiourea such as diethyldithiocarbamate, Zn-di-n-butyldithiocarbamate, Zn-ethiphenyldithiocarbamate, Te-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, pipecoline pipecolyldithiocarbamate; Examples of the vulcanization accelerator include ethylenethiourea, diethylthiourea and the like;

As a vulcanization accelerating auxiliary, a general rubber auxiliary can be used in combination, for example, zinc white (about 5 phr), stearic acid, oleic acid and Zn salts thereof (2 to 2 phr). (About 4 phr) may be used.

In order to manufacture the pneumatic tire of the present invention, first, a cylindrical thermoplastic resin film cut into a predetermined length in the longitudinal direction (cut into a circle) is fitted to a tire forming drum, and this cylindrical shape is formed. By laminating tire members such as a carcass layer, a side portion, a belt layer, and a tread on a thermoplastic resin film, a cylindrical thermoplastic resin is formed on the inner surface of a green tire made of unvulcanized rubber as an air permeation preventing layer. Place a resin film.

Next, the terminal in the width direction of the thermoplastic resin film is positioned between 1 mm and 30 mm in the side portion direction along the inner surface of the green tire from the bead toe, and then the inside of the green tire is placed in a mold. A dry gas or an inert gas having a moisture content of 10% or less, preferably a moisture content of 1% to 5%, an oxygen content of 10% or less, preferably an oxygen content of 1% to 5% and a temperature of 170 to 250 ° C is introduced. By performing vulcanization.

The dry gas is, for example, air. The inert gas is, for example, nitrogen. Moisture ratio 1
The reason why the content is set to 0% or less is that the thermoplastic resin film is easily hydrolyzed such as nylon. The oxygen content is set to 10% or less in order to prevent oxidative deterioration due to heat during vulcanization.

The reason for setting the temperature to 170 to 250 ° C. is as follows.
When the temperature is lower than 70 ° C., when a dry gas or an inert gas having a small heat capacity is used as a heat medium, the temperature rise is slow and the vulcanization productivity is poor. This is because when the internal pressure is reduced to the atmospheric pressure at the end of vulcanization, the gas that has permeated into the resin film expands and causes blister failure.

Further, a cylindrical thermoplastic resin film may be arranged on the inner surface of the green tire made of unvulcanized rubber via a crosslinkable adhesive layer. As the crosslinkable adhesive layer, for example, a phenol resin adhesive, an epoxy resin adhesive, or the like may be used. In the case where the crosslinkable adhesive layer is interposed in this way, the thermoplastic resin film is applied to the tire inner rubber by lowering the temperature in the latter half of the vulcanization while promoting the crosslinking of the crosslinkable adhesive layer by raising the initial temperature of the vulcanization to a high temperature. It is good to adhere firmly.

[0034]

EXAMPLE Nylon 6 (N6) (CM4061 manufactured by Toray Co., Ltd.) was used as a thermoplastic resin to a thickness of 0.1 m by a conventional method.
m, and the cylindrical film is arranged on the tire inner surface as an air permeation preventing layer, and the width direction terminal of the film is arranged at a position of 10 mm in the side portion direction from the bead toe along the tire inner surface. Thus, a pneumatic radial tire having a tire size of 205 / 65R15 and a structure shown in FIG. 1 was manufactured (the tire of the present invention).

For comparison, a pneumatic radial tire similar to the above-described tire of the present invention was manufactured except that the terminal in the width direction of the film was extended from the inner surface of the tire to the bead heel through the bead base portion (conventionally). tire).

The fit of these tires with the rim was evaluated as follows. Table 1 shows the results.

Fitability with rim: When the tire was assembled to the rim, the distance from the rim flange to the rim check line was measured at eight equal intervals in the tire circumferential direction. The standard deviation of the measurement result is calculated for each tire, and the reciprocal thereof is indicated by an index with the conventional tire being 100. The larger the index value, the better the fit with the rim.

[0038]

[Table 1]

From Table 1, it can be seen that the tire of the present invention has a better fit with the rim than the conventional tire.

As with conventional tires, the rim fitting of a tire using a thermoplastic film up to the bead heel to reduce the weight of the tire is small because the frictional resistance of the film is small.
The rim fitting property is poor, and the problem that the tire and the rim deviate during running tends to occur. On the other hand, in the tire of the present invention, since the heel portion is not covered with the thermoplastic film from the bead base and the rubber is exposed, the disadvantages of the conventional tire are solved, and the tire rim weight is reduced without deteriorating the rim fitting property. Becomes possible.

[0041]

As described above, according to the present invention, in a pneumatic tire in which an air permeation preventing layer is formed of a cylindrical thermoplastic resin film having no joint portion, the widthwise terminal of the thermoplastic resin film is reduced. Since it is arranged between 1 mm and 30 mm in the side portion direction from the bead toe along the tire inner surface, the fitting property with the rim can be improved.

[Brief description of the drawings]

FIG. 1 is a meridional half sectional view of an example of a pneumatic tire of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass layer 3 Cylindrical thermoplastic resin film 4 Bead toe 5 Side part 6 Bead base part 7 Bead heel M 1 mm-30 mm

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 101: 12 B29K 101: 12 105: 24 105: 24 B29L 30:00 B29L 30:00 (72) Inventor Takehiko Sakaushi 2-1 Oiwake, Hiratsuka-shi, Kanagawa F-term in Yokohama Rubber Co., Ltd. Hiratsuka Factory 4F202 AA45 AH20 CA21 CB01 CY02 CY11 4F203 AA45 AH20 DA11 DB01 DC01 DC03 DK01

Claims (5)

[Claims] 1. A pneumatic tire in which an air permeation preventing layer is formed of a cylindrical thermoplastic resin film having no joint portion, a width direction end of the thermoplastic resin film is directed from a bead toe to a side portion along an inner surface of the tire. 1mm ~
A pneumatic tire arranged between 30 mm. 2. A cylindrical thermoplastic resin film is disposed as an air permeation preventing layer on an inner surface of a green tire made of unvulcanized rubber, and a width direction terminal of the thermoplastic resin film is applied from a bead toe to an inner surface of the green tire. Along the side part between 1mm ~ 30mm, then
In the mold, a moisture content of 1
0% or less, oxygen content 10% or less, temperature 170 to 250
A method for producing a pneumatic tire, which comprises vulcanizing by introducing a dry gas or an inert gas at a temperature of ° C. 3. The method according to claim 2, wherein the dry gas is air. 4. The method according to claim 2, wherein the inert gas is nitrogen. 5. A cylindrical thermoplastic resin film is arranged on the inner surface of a green tire made of unvulcanized rubber via a crosslinkable adhesive layer, and the initial vulcanization temperature is raised to increase the temperature of the crosslinkable adhesive layer. 5. The method for producing a pneumatic tire according to claim 2, wherein the crosslinking is promoted and the temperature is lowered late in the vulcanization to firmly adhere the thermoplastic resin film to the tire inner rubber.