JPH0952502A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a tire, so as to prevent splice open, by providing an air transmission preventing layer composed of a film of a polymer composition including thermoplastic resin having the specified air transmission factor and the Young's modulus or the blend of thermoplastic resin and elastomer, and for circumferentially covering the inner surface of the tire doubly or more. SOLUTION: An air transmission preventing layer having a plurality of layers, composed of a film 2 of a polymer composition including thermoplastic resin having the air transmission factor of 25×10<12> cc.cm/cm<2> .sec.cmHg or less and the Young's modulus in the range of 1 to 5O0MPa or the blend of thermoplastic resin and elastomer, and for substantially continuously covering the inner surface of the tire in the tire circumferential direction doubly or more is provided. In a method for arranging the polymer film 2, a splice part X is provided on one part, or two polymer films 2 are so provided that a splice part X may not be at the same position as a splice part Z on the inner surface of the tire. Moreover, a plurality of films may not be adjacent to each other if they are not on the outermost layer.

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 more particularly to a pneumatic tire which has a plurality of air permeation preventive layers to reduce the weight of the tire and prevents splice opening during the tire molding process. Regarding

[0002]

2. Description of the Related Art Reduction of the fuel consumption rate is one of the major technical problems in automobiles, and as a measure against this, there is an increasing demand for lighter 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.

Techniques have been proposed in which various materials are used as the inner liner layer of a pneumatic tire in place of low gas permeability rubber such as butyl rubber. For example,
-31761 discloses that the inner surface of a vulcanized tire has an air permeability coefficient [cm ³ (standard state) / cm · sec · mmHg] of 1 at 30 ° C.
It is disclosed that a solution or dispersion of synthetic resin such as polyvinylidene chloride, saturated polyester resin, polyamide resin or the like having a concentration of 0 × 10 ⁻¹³ or less and 50 × 10 ⁻¹³ or less at 70 ° C. is applied in an amount of 0.1 mm or less. There is.

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 a methoxymethylated nylon Polymer film of polymerized nylon, blend of polyurethane and polyvinylidene chloride, blend of polyurethane and polyvinylidene fluoride (film thickness 1
0-200 [mu] m).

Further, Japanese Patent Laid-Open No. 5-318618 discloses that
A pneumatic tire using a thin film of methoxymethylated nylon as an inner liner is disclosed. According to this technology, a solution or emulsion of methoxymethylated nylon is sprayed or applied to the inner surface of a green tire, and then the tire is vulcanized. Alternatively, a pneumatic tire is manufactured by spraying or applying a solution or emulsion of methoxymethylated nylon on the inner surface of the tire after vulcanization.

Further, Japanese Patent Laid-Open No. 6-40207 discloses that
A non-air permeable layer composed of a polyvinylidene chloride film or an ethylene vinyl alcohol copolymer film, and a polyolefin film, an aliphatic polyamide film, or a multilayer film having an adhesive layer composed of a polyurethane film as an air permeation preventive layer of a tire. There is an example in use.

[0007]

As described above, various materials for the inner liner layer of a pneumatic tire have been proposed in place of butyl rubber, but have not yet been put to practical use. Under such circumstances, we have previously found that a new air permeation preventive layer material containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer has an air permeation coefficient of 25 × 10 ⁻¹² cc · cm / cm. ²・ sec ・ cmHg
A polymer composition for a tire having a Young's modulus of 1 to 500 MPa was proposed below (for example, Japanese Patent Application Nos. 7-150353, 7-28318, 7-28257 and 7-268).
No. 44, No. 7-28320, No. 7-11752, etc.).

By the way, when manufacturing the air permeation preventive layer, as shown in FIGS. 1 (a) and 1 (b), in the case of a conventional butyl rubber liner, the first molding step and the second molding step are performed at the time of processing. 1B, the spliced portion of the film liner is opened because the joint portion 3 of the film liner 2 in the lower portion of the carcass layer 1 is stretched by the lift and the tack of the film liner is small due to the lift in the second molding step shown in FIG. 1B. There is a problem that it ends up (Splice Open 4).

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to eliminate the above-mentioned problems of the prior art, to reduce the weight of the tire, and to provide a pneumatic tire that prevents splice opening during the tire molding process.

[0010]

According to the present invention, a thermoplastic resin having an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less and a Young's modulus of 1 to 500 MPa or a thermoplastic resin. There is provided a pneumatic tire having a plurality of air permeation preventive layers, each of which is formed of a film of a polymer composition containing a blend of an elastomer and an elastomer, and covers the inner surface of the tire substantially continuously in the tire circumferential direction for two or more revolutions. According to the invention, the air permeability coefficient is also 25 × 10 ⁻¹² cc · cm / cm ² ·
sec ・ cmHg or less, Young's modulus of 1 ~ 500MPa, multiple layers of air permeation that substantially covers the inner surface of the tire, consisting of two or more films of a polymer composition containing a thermoplastic resin or a blend of a thermoplastic resin and an elastomer Provided is a pneumatic tire having a preventive layer, in which splice portions of the film are arranged so as not to coincide with each other on the tire circumference.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the structure, operation and effect of the present invention will be described in detail. Film forming the air permeation preventive layer of a pneumatic tire according to the present invention, air permeability ^{25 × 10 -12 cc · cm /} cm 2 · sec · cmHg or less, - preferably 5 × 10 ^{-1 2} cc cm / cm ² · sec · cmHg and Young's modulus is 1 to 500 MPa, preferably 10 to 300 MPa
And the thickness of the film is preferably 0.02 to
0.2 mm, more preferably 0.05 to 0.2 mm,
The total layer is preferably 1.2 mm or less,
More preferably, it is 0.5 mm. 25% air permeability
If it exceeds 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, wrinkles or the like occur during the molding of the tire, which lowers the molding processability.

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 polymer mixtures of these or these and elastomers.

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), and N-alkoxyalkylated products thereof, for example, 6-nylon methoxymethylated product, 6-610-nylon methoxymethylated product, 612-nylon methoxymethylated product, polyester Resin (eg polybutylene terephthalate (PBT), polyethylene terephthalate (PE
T), polyethylene isophthalate (PEI), PET
/ PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylenediimidic acid / polybutyrate terephthalate copolymer), polynitrile resin (eg polyacrylonitrile) (PA
N), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resin (for example, polymethylmethacrylate ( PMMA), polyethylmethacrylate), polyvinyl resins (eg vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDV)
C), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer), cellulosic resins (eg cellulose acetate, cellulose acetate butyrate), Fluorine-based resin (for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF),
Examples thereof include polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer), and imide resin (for example, aromatic polyimide (PI)).

The elastomer that can be blended with the thermoplastic resin is not particularly limited as long as it has the above-mentioned air permeability coefficient and Young's modulus as a blend, and examples thereof include the following. Diene rubber and its hydrogenated products (for example, NR, IR,
Epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR),
Olefin rubber (for example, ethylene propylene rubber (E
PDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (A
CM), ionomers), halogen-containing rubbers (eg Br
-IIR, Cl-IIR, bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), CR, hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid modified chlorinated Polyethylene (M-CM)), silicone rubber (for example, methyl vinyl silicone rubber, dimethyl silicone rubber, methylphenyl vinyl silicone rubber), sulfur-containing rubber (for example, polysulfide rubber), fluororubber (for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber) Rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber, thermoplastic elastomer (for example, styrene elastomer, olefin elastomer, ester elastomer, ureta) System elastomer, polyamide-based elastomer) and the like.

When the compatibility between the specific thermoplastic resin and the elastomer component is different, it is preferable to use a suitable compatibilizing agent as the third component to make them compatible.
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 be a copolymer having a group, an oxazoline group, a hydroxyl group and the like. These may be selected according to the type of thermoplastic resin and elastomer component to be mixed,
Commonly used ones are styrene / 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 Copolymers, reactive phenoxines and the like can be mentioned. The amount of the compatibilizer is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (total of the thermoplastic resin and the elastomer component).

When the thermoplastic resin and the elastomer are blended, the composition ratio of the specific thermoplastic resin (A) and the elastomer component (B) is not particularly limited, and the film thickness, the air permeation resistance, the flexibility The weight ratio (A) / (B) is preferably 10/9, although it may be appropriately determined depending on the balance of properties.
0-90 / 10, more preferably 20 / 80-85 / 1
5

In addition to the above-mentioned essential polymer components, the polymer composition according to the present invention is mixed with other polymers such as the above-mentioned compatibilizer polymer within a range that does not impair the required properties of the tire polymer composition of the present invention. can do. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer component, to improve the film moldability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material used include polyethylene (PE), polypropylene (PP),
Examples thereof include polystyrene (PS), ABS, SBS, polycarbonate (PC) and the like. Further, olefin copolymers such as polyethylene and polypropylene, maleic acid-modified products thereof, and glycidyl group-introduced products thereof can also be mentioned. In the polymer composition according to the present invention, a filler, carbon black, quartz powder calcium carbonate, alumina, titanium oxide, etc., which are generally blended in the polymer blend, may be used in order to reduce the air permeability coefficient and Young's modulus requirements. Unless otherwise specified, they can be optionally mixed.

According to the present invention, as shown in FIG. 2, a thermoplastic resin having an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less and a Young's modulus of 1 to 500 MPa or a thermoplastic resin is used. There is no particular limitation on the method of disposing the polymer film 2, which is composed of a film of a polymer composition containing a blend of a resin and an elastomer, and is arranged so as to cover the tire inner surface substantially continuously in the tire circumferential direction for two or more laps. Although it is possible to consider without limit, for example, FIG. 2 (A-1) (cross section),
As shown in (A-2) (cross section), at least two layers of the polymer film 2 are present on substantially the entire inner peripheral surface of the tire. For the splicing method, see FIG.
In the tire shown in (B-1) (side surface), the polymer film 2 is continuously formed on the inner surface of the tire in a substantially continuous manner in the tire circumferential direction.
This is an example in which the splice portion is covered by more than one circumference, and the splice portion is one place of the splice portion X. Further, in the tire shown in FIG. 2B-2 (side surface), two polymer films 2 are arranged on the inner surface of the tire so that the splice portion Y and the splice portion Z do not coincide with each other at the same position on the tire circumference. Here is an example. The materials of the two or more polymer films may be the same or different. Further, the polymer film may be attached or adhered after molding according to a conventional method, or may be applied according to a conventional method. Further, the plurality of films need not be adjacent to each other unless they are the outermost layers, and for example, a carcass layer may be present between them.

Next, according to the present invention, the step amount S (mm) at the splice portion and the peripheral length L (mm) at the crown center portion shown in FIG. 3 are -0.05≤S / L≤0.05. Is preferable, and uniformity is deteriorated outside this range, which is not preferable. Figure (3-a)
In such cases, S> 0, and in the case of FIG. 3B, S <0.

Further, according to the present invention, as shown in FIG. 4, since the polymer film 2 arranged inside the carcass layer 1 is arranged in multiple layers, stress is concentrated only on the splice portion even if lift is applied in the second molding step. Therefore, peeling of the splice portion (splice opening) does not occur even when the lift is extended in the direction.

[0021]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples. Examples 1 to 9 and Comparative Examples 1 to 5 As shown in Table I, tires (size: 165SR13, rim size: 13) having an air permeation preventive layer configured as shown in Table I using polymer films made of materials A to D are used. × 4
1 / 2-J) was prepared. The following tests were performed on these tires and the conventional standard examples 1 and 2. Table I shows the results
Shown in

Air dripping test method The tire after vulcanization was cut, and if air dripping failure was observed, it was judged as bad (x), and if not observed, it was judged as good (◯).

Test Method for Molding Workability During tire molding, if the material was stretched, it was rated as bad (x), and if it was not stretched, it was rated as good (◯).

Splice Open Test Method Regarding the tire after vulcanization, it is judged as bad (x) when the splice part of the air permeation preventive layer is open, and good (◯) when it is not open.

Uniformity test method RFV is measured according to JASO C-607-87 (Uniformity test method for automobile tires). The reciprocal of the measured value of Standard Example 2 which is a conventional typical tire is set to 100 and displayed as an index (the larger the number, the better).

Air leak test method (pressure drop rate) Initial pressure of 200 kPa, room temperature of 21 ° C., and no load for 3 months. The internal pressure measurement interval is every 4 days, and the measured pressure is
As Pt, initial pressure Po, and elapsed days t, the α value is obtained by regressing to the following equation Pt / Po = exp (−αt). Using the obtained α, t = 30
Substituting (day), β = [1-exp (−αt)] × 100 is obtained. This value β is the pressure drop rate per month (% /
Month).

[0027]

[Table 1]

[0028]

[Table 2]

Table I Footnotes (All parts indicate parts by weight) Material A: Nylon 6 (N6) (Toray CM4061)
28 parts, nylon MXD6 (MXD6) (Mitsubishi Gas Chemical Reny 6002) 42 parts, maleic acid modified ethylene propylene rubber (M-EPM) 30 parts and methylene dianiline 0.18 parts, having an air permeability coefficient of 2.13. × 1
^0-12 cc · cm / cm ² · s. cmHg) Young's modulus is 257 MPa
Material. Material B: N6 25.2 parts, MXD6 37.8 parts, Masterbatch A (butyl rubber bromide: Exxon Chemical Exxon Bromobutyl 2244 100 parts, Tokai Carbon Carbon Black GPF: Seast V 60
Part, stearic acid 1 part, petroleum-based hydrocarbon resin Essolets 1102 10 parts, paraffin-based process oil 10 parts) 48.9 parts, Mitsui Petrochemical high sex million 240M (EEA), zinc oxide 1.5 parts, DM0.
It consists of 5 parts and 0.3 parts of sulfur and has an air permeability coefficient of 0.
84 × 10 ^-12 cc · cm / cm ² · sec. Material with cmHg and Young's modulus of 244 MPa Material C: N6 25.2 parts, MXD6 37.8 parts, B
It consists of 27.0 parts of r- (polyisobutylene-p-methylstyrene) (EXPRO 89-4 manufactured by Exxon Chemical) and nylon 6 / nylon 66 / nylon 610 (CM4001 manufactured by Toray), and has an air permeability coefficient of 0.63 ×.
10 ^-12 cc · cm / cm ² · sec. cmHg Young's modulus 317MP
Material of a Material D: Butyl rubber (Air permeability coefficient 55 × 10 ^-12 cc ・
cm / cm ² · sec. cmHg, Young's modulus 15MPa)

[0030]

As described above, according to the present invention,
Air permeability coefficient is 25 × 10 ^-12 cc · cm / cm ² · sec. cm
A preferable 0.02-0.2 mm-thick film of a polymer composition containing a thermoplastic resin having a Young's modulus of 1 to 500 MPa or less and a blend of a thermoplastic resin and an elastomer of Hg or less is used as an air permeation preventive layer, and the inner circumference of the entire tire is used. By providing multiple layers on the surface, 1) the gauge is extremely thin, which enables significant weight reduction, and 2) the gauge is extremely thin, so air gaps do not occur at the steps as in the past and vulcanization failure occurs. Even if the gauge is thin, since the modulus is high, the effect that the moldability is not deteriorated can be achieved.

[Brief description of drawings]

FIG. 1 is a view for explaining a problem that a splice open of a film liner occurs during a conventional tire molding process.

FIG. 2 is a drawing showing the arrangement of a polymer film of an air permeation preventive layer according to the present invention in a tire cross section and a side view, and some embodiments thereof are shown in FIGS.
1) and (B-2).

FIG. 3 is a diagram illustrating uniformity requirements of a polymer film of an air permeation preventive layer according to the present invention.

FIG. 4 is a view explaining that the problem of splice opening does not occur in the air permeation preventive layer according to the present invention.

[Explanation of symbols]

 1 ... Carcass layer 2 ... Film liner (polymer film) 3 ... Splice of film liner 4 ... Splice open S ... Step amount X, Y, Z ... Splice part

Claims (4)

[Claims] 1. An air permeability coefficient of 25 × 10 ⁻¹² cc · cm /
cm ² · sec · cmHg or less, Young's modulus of 1 ~ 500MPa made of a thermoplastic resin or a polymer composition film containing a blend of a thermoplastic resin and an elastomer, the tire inner surface substantially continuously in the tire circumferential direction A pneumatic tire having a plurality of air permeation preventive layers covering two or more laps. 2. An air permeability coefficient of 25 × 10 ⁻¹² cc · cm /
cm ² · sec · cmHg or less, a Young's modulus of 1 ~ 500MPa, a plurality of layers of a thermoplastic resin or a polymer composition containing a blend of a thermoplastic resin and an elastomer, a plurality of layers substantially covering the inner surface of the tire The pneumatic tire having the air permeation preventive layer and the splice portions of the film arranged so as not to coincide with each other at the same position on the tire circumference. 3. The thickness of one air permeation preventive layer is 0.02.
The pneumatic tire according to claim 1 or 2, which has a diameter of 0.2 mm. 4. The total thickness of the plurality of air permeation preventive layers is 1.
The pneumatic tire according to any one of claims 1 to 3, which has a diameter of 2 mm or less.