JPH11254917A - Pneumatic safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic safety tire for maintaining durability at the time of internal pressure filling, and sharply improved in light weight and run flat travel performance. SOLUTION: In this pneumatic safety tire, a carcass layer composed of a side wall and an organic fiber cord, a belt layer, and a tread part are arranged in order, and are reinforced respectively, and also a reinforced rubber layer 28 having a lunate cross section is equipped in the inner periferal surface of the carcass layer 18 of the side wall 16. The organic fiber cord consists by stranding an organic fiber raw yarn having core sheath structure composed of the sheath part wrapping a core part and around the core part, and the core and sheath parts are composed of polyester and aliphatic polyamide respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic safety tire which reinforces a tire side portion and enables good run flat running.

[0002]

2. Description of the Related Art Run-flat running is possible with a pneumatic tire (that is, a tire is punctured by foreign matter such as a nail or a metal piece being pushed into the tire while the tire is running, and the tire internal pressure becomes 0 kg / m). Even if it reaches cm ² , a tire that can continue to travel for a considerable distance safely in that state and reach a desired place (for example, a service station where tires can be changed) (referred to as a pneumatic safety tire)
Is a comparison between a core type in which a metal or synthetic resin annular core is attached to the rim part in the tire air chamber and a crescent-shaped cross section on the inner surface of the carcass from the bead part of the tire sidewall to the shoulder area. A side reinforcement type in which a layer of a target hard rubber is arranged and reinforced is known. Of these two types, the core type has a high load-bearing capacity in run-flat driving, so it is intended for use in luggage-carrying vehicles and military vehicles where ride comfort is not an issue. However, they are small, and have been evaluated as appropriate for passenger cars that emphasize riding comfort.

[0003] Among these, the simplest and most effective measure is to provide an annular reinforcing rubber layer having a crescent cross section or the like on the inner surface side of the carcass ply or a plurality of carcass ply on the thinnest and low rigidity sidewall portion of the normal tire. There is a so-called side reinforced run flat tire which is arranged between ply layers to support wheel loads. This side reinforcement run flat tire bears the load at the time of normal air pressure mainly by the tension of the reinforcing cord due to the internal pressure like the normal tire,
On the other hand, when the internal pressure is not punctured, the support is intended to be supported by the member rigidity inherent to the sidewall.

At present, as a rubber reinforcing fiber cord for a carcass ply material of a tire for a normal running passenger car, PET (polyethylene terephthalate) is generally used in view of its dimensional stability, moisture resistance stability, moderate rigidity, and low cost. Fiber is preferred and widely used. In addition, rayon and nylon are also partially used.However, rayon is low in strength and carcass strength design, the amount of fiber used is higher than polyester, and it is disadvantageous at high price. Nylon has problems such as low elastic modulus, large heat shrinkage, poor creep properties, poor flat spot properties, poor side unevenness, and insufficient uniformity. It has disadvantages and is inferior to PET as a whole.

[0005] As a carcass ply cord fiber of this side-reinforced run-flat tire, PET (polyethylene terephthalate) fiber used in a general tire is applied, and when run-flat (no internal pressure) is run, a thick side-reinforced rubber layer is formed. It was found that the temperature rose due to the large heat generation, and the separation occurred between the polyester fiber cord and the rubber, causing early failure.

In the prior art, a reinforcing rubber layer having a crescent cross section is mainly arranged inside the carcass layer of the side wall portion, and the carcass layer is usually formed of one or two layers in order to further increase the rigidity of the side wall portion. Need more 3-4 layers,
There is a problem in that the weight increases, and furthermore, the rolling resistance and the handling stability deteriorate.

On the other hand, in recent years, as the fuel economy of vehicles has been reduced, it has been strongly required to reduce the weight of tires. In order to reduce the weight of tires, the thickness of tire sidewalls has been increasingly reduced. Furthermore, it is naturally required to be able to perform run-flat running in which the internal pressure of the tire is 0 kg / cm ² , and at the same time, to perform in normal running when filling the internal pressure.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a lighter weight while maintaining a high level of normal running performance when filling with an internal pressure, and to achieve a run flat compared to a safety tire having a conventional reinforcing rubber layer. It is an object of the present invention to provide a pneumatic safety tire having significantly improved running performance.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies, particularly focusing on a carcass ply material of a tire. As a result, an organic fiber cord having a specific core-sheath structure was used as a carcass ply material. By the following means such as using
The inventors have found that the object can be achieved, and have completed the present invention.

That is, (1) In the pneumatic safety tire of the present invention, from the both ends of the cylindrical crown portion, radially inward, sidewalls in which bead rings are embedded at the tips are continuous, and from one of these sidewalls. It consists of at least one organic fiber cord radial carcass ply layer between the crown part and the other side wall,
A carcass layer in which both ends are wound up around the bead ring in the axial direction and fixed, a plurality of non-extensible belt layers and a tread portion are sequentially arranged on the outer periphery of the crown portion of the carcass layer to reinforce each. In addition, the inner peripheral surface of the carcass ply layer of the sidewall, or a side-reinforced pneumatic safety tire provided with an annular reinforcing rubber layer between a plurality of carcass ply layers, wherein the organic fiber cord is a core and the core A cord formed by twisting an organic fiber yarn having a core-sheath structure comprising a sheath portion surrounding the sheath, wherein the core portion is made of polyester, and the sheath portion is made of an aliphatic polyamide.

(2) In the above item (1), the polyester is preferably selected from the group consisting of polyethylene terephthalate and polyethylene naphthalate.

(3) In the above item (1), the aliphatic polyamide is preferably selected from the group consisting of polyhexamethylene adipamide and polytetramethylene adipamide.

(4) In the above item (1), the weight ratio of core / (core + sheath) is preferably 0.5 to 0.9.

(5) In the above item (1), it is preferable that at least one down carcass layer is further disposed between the sidewall portion and an outer surface of the carcass layer.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As the sheath material of the core-sheath fiber of the organic fiber cord used in the present invention, an aliphatic polyamide is used, such as polyhexamethylene adipamide or polytetramethylene adipamide. Are preferably included. Polyester is used as the material of the core portion, and examples thereof include polyethylene terephthalate and polyethylene naphthalate. The material of the sheath portion is selected from the adhesiveness to rubber and heat resistance, and the material of the core portion is selected from the elastic modulus-heat shrinkage characteristics. The weight ratio of core / (core + sheath) is 0.5 to 0.9.
Is preferred, and 0.7 to 0.8 is more preferred. If the proportion of the aliphatic polyamide in the sheath portion is too large, the advantages of the dimensional stability and elastic modulus of the original polyester are impaired, and the properties are close to those of polyamide, and uniformity, flat spots, side irregularities and the like are impaired. Conversely, if the weight ratio of the sheath portion is too small, the thickness of the sheath layer becomes too thin, and the peeling durability is impaired, which is not preferable.

The core-sheath fiber used in the present invention can be produced according to the same production method as that for known clothing and the like. The position of the core of this fiber is, from the viewpoint of peel resistance,
Preferably it is not eccentric. Furthermore, this fiber raw yarn is subjected to a first twist and then a first twist to obtain a twin-twisted raw cord. After weaving the raw cord to form a woven fabric, an adhesive is applied, and a dry heat tension heat treatment is performed to obtain a dipping treatment. Further, the coated rubber is topped from both upper and lower surfaces to obtain a coated counter. This is cut into appropriate dimensions and used for tire manufacture. Although the number of carcass ply layers is at least one, it is usually used in a structure in which two or more carcass ply layers are overlapped in order to more effectively support a no-internal-pressure load during run flat running.

The inner peripheral surface of the carcass ply layer or between a plurality of carcass ply layers used in the present invention, and, if there is an inner liner, an annular reinforcing rubber layer inside the inner liner,
For example, a reinforcing rubber layer having a crescent cross-sectional shape needs to have a function (for example, high hardness) of suppressing compression deformation inside the sidewall in order to suppress deflection of the sidewall when air from the pneumatic safety tire is released. As the rubber component of the reinforcing rubber layer used to exhibit this function,
For example, natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), and isoprene rubber (IR) can be mentioned. Among them, natural rubber and butadiene rubber are preferable from the viewpoint of effects.

In the pneumatic safety tire of the present invention,
From the vicinity of the bead ring, passing between the sidewall and the outer surface of the carcass layer, and further reaching the vicinity of the other bead ring, at least one of the down carcass layers is provided. It is preferred in that respect.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given using examples and comparative examples.

FIG. 1 shows an example of a schematic sectional view of a grounded pneumatic safety tire. In the pneumatic safety tire 10 of the present invention, the head portion is fitted to the flange of the rim 30, the tread portion 24 is grounded with the tread shoulder 26 as an end, and radially inward from both ends of the cylindrical crown portion. A bead filler 14 and a sidewall 16 in which a bead ring 12 is buried are connected to the tip, and a portion from one of the sidewalls 16 through the crown portion to the other sidewall is composed of two organic fiber cord radial ply layers, A carcass layer 18 whose both ends are wound around the bead ring 12 in the axial direction and fixed is not shown, but if necessary, the side wall 16 and the outer surface of the carcass layer 18 can be connected from the vicinity of the bead ring 12. Between the at least one down carcass layer and the carcass layer 1 A plurality of inextensible belt layer 22 on the crown portion outer periphery of the further inner liner on the inner side of the carcass layer 18, and the tread portion 2
4 are sequentially arranged to reinforce each other, and a crescent-shaped reinforcing rubber layer 28 (for example, having a maximum thickness of 7 mm) for supporting the load on the inner peripheral surface of the inner liner inside the carcass layer 18 of the sidewall 16. , Hardness 80 °).

FIG. 2 is a schematic sectional view of a normal pneumatic tire in a state where the air pressure becomes 0 kg / cm ² under a load.

The tire 40 has no reinforcing rubber layer. The numbering and description of each member and part are the same as in FIG.
In the punctured state, the sidewall 16 is extremely bent,
Contact occurs at positions m and n, and satisfactory run-flat running becomes difficult.

Various evaluation methods used in Examples and Comparative Examples are as follows. -Hardness is represented by JIS A and JIS K6301-1.
995.

Runflat durability: 0 kg / cm internal pressure
^{In 2} , the vehicle was run on a straight drum with a load of 570 kg and a speed of 89 km / h, and the running distance until the occurrence of a failure was represented by an index with the control (PET carcass product) being 100. The larger the index, the better the run flat durability.

The twist coefficient is calculated by the formula R = N × (0.125 ×
D / ρ) ^1/2 × 10 ^-3 (where, N: number of twists of the cord (times / 10 cm), D: total decitex of the cord (dTE)
X) number, ρ: density of core-sheath fiber). (Examples and Comparative Examples) Preparation of core-sheath fiber cord used for carcass ply layer of tire of the present invention Composite using polyethylene terephthalate (PET) chip and polyhexamethylene adipamide (66 nylon) chip as raw materials PET core,
A core-sheath fiber filament having a total fineness of 1670 dTEX in which 66 nylon was used as a sheath portion was prepared. At this time, the hole diameter of the spinneret and the polymer discharge amount were adjusted to change the polymer ratio,
The weight ratio of T / 66 nylon was 75/25.

Further, the above-mentioned fiber filaments were subjected to a ring twisting machine to calculate the number of lower twists × the number of upper twists as 42 × 42 times / 10 c.
m and a twin-stranded raw cord of 1670 dTEX / 2. The twist coefficient was 0.52. Then, it was immersed in an RFL adhesive aqueous solution and dried and heat-treated.

Preparation of Polyethylene Terephthalate Fiber Cord Used for Carcass Ply Layer of Tire of Comparative Example A 1670 dTEX fiber filament was prepared from the PET chip used for preparing the carcass ply cord of the tire of the present invention as a raw material.

Using a ring twisting machine, this fiber filament was made into a twin-twisted raw cord of 1670 dTEX / 2, with the number of lower twists × the number of upper twists being 42 × 42 times / 10 cm. The twist coefficient was 0.52.

The twisted cord was subjected to adhesive application and heat treatment (dip treatment) under the following conditions.

First, the twisted cord is immersed in a resorcinol-formalin latex-based adhesive, the treatment temperature in the drying zone is set to 160 to 170 ° C., the treatment time is set to 60 to 160 seconds, and the treatment temperature in the heat setting zone is set to 230. ~ 2
At 50 ° C., the treatment time is 60 to 180 seconds, and the cord tension is 0.8 to 1.4 g / dTEX. Furthermore, the processing temperature of the normalizing zone is
Set 20-70 ° C lower (for example, 180-210 ° C),
The cord tension is about 1/10 of the heat set zone (0.
08 to 0.14 g / dTEX), and the cord is subjected to dry heat treatment for a treatment time of 60 to 120 seconds.

The adhesive is not particularly limited. For example, resorcin-polysulfide and excess resorcin-formaldehyde condensate are mixed at a solid content ratio of 20: 100, and 18 parts of the solid content is taken out of the mixture, and 9 parts are taken out. Of 28% aqueous ammonia, and then water to make the total amount 50 parts to completely dissolve, and then 50 parts of resorcin-formaldehyde condensate / latex (RFL)
Was used. Here, RFL was adjusted to the following composition and aged for 48 hours or more.

-Water 518.8 (parts by weight)-Resorcin 11.0-Formalin (37%) 16.2-Ammonium hydroxide (28%) 10.0-Vinyl pyridine-244.0 copolymer weight of styrene-butadiene Coated latex (41%) The physical properties of the cord after heat treatment for adhesion are 2.00 g / dT
The elongation under an EX load (based on the method of JIS L1017-1983) is preferably 7.0% or less from the viewpoint of dimensional stability (creep property) when a rubber product is used.

The pneumatic safety tire used has a tubeless structure with a size of 225 / 60R16. As the carcass ply (body ply) layer, the embodiment uses the core-sheath type fiber cord, and the comparative example uses the PET fiber cord. Use each of these dip cords in the end number of 50 / 5cm, topping the coating rubber from the top and bottom, use 3 of them, that is, add them to the two folded carcass plies, and add one down to the outermost layer Using a 3Ρ carcass structure in which carcass is arranged, as a crescent-shaped reinforcing rubber layer, the hardness after vulcanization is 80 ° with the composition according to Table 1,
Using a rubber with a maximum thickness of 7 mm, as a belt layer,
In a 1 × 5 structure, a steel cord having a wire diameter of 0.25 mm, the number of shots is 40/5 cm, and the steel cord angle is 20 ° with respect to the tire circumferential direction. Created tires.

The run-flat durability of the tire of the embodiment is expressed by the index of the run-flat durability of the tire of the comparative example.
In this case, the index was a good value greatly exceeding 100 by an index.

In addition, when the state of the broken tire after running until it breaks down is visually observed, the pneumatic safety tire of the present invention is broken due to the occurrence of cracks in the reinforcing rubber layer, whereas the tire of the comparative example is broken. It was a fatal destruction of separation between the carcass ply cord and the coating rubber.

The durability of the test tire at the time of filling with the internal pressure was at a level without any problem.

[0037]

[Table 1]

As described above, the pneumatic stable tire of the present invention is excellent in run flat durability while maintaining the durability at the time of filling the internal pressure.

When a PET fiber cord is used as the carcass ply layer (Comparative Example), the run flat durability deteriorates.

[0040]

As described above, in the pneumatic safety tire of the present invention, durability is maintained at the time of internal pressure filling by using an organic fiber cord having a specific core-sheath structure as a carcass ply layer, and lightness and lightness are improved. It has an excellent effect that run flat durability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an exemplary grounded pneumatic safety tire of the present invention.

FIG. 2 is a schematic cross-sectional view of a punctured normal pneumatic tire grounded under a load.

[Sign]

 DESCRIPTION OF SYMBOLS 10 Pneumatic safety tire 12 Bead ring 14 Bead filler 16 Side wall 18 Carcass layer 22 Belt layer 24 Tread part 26 Tread shoulder 28 Reinforcement rubber layer 30 Rim 40 Pneumatic tire

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B60C 13/00 B60C 13/00 F

Claims (5)

[Claims] 1. A side wall having a bead ring buried at a tip portion thereof extends from both ends of a cylindrical crown portion toward a radially inner side, and a gap extending from one of the sidewalls to the other sidewall through the crown portion. A carcass layer consisting of at least one organic fiber cord radial carcass ply layer, the both ends of which are wound up around the bead ring in the axial direction and fixed, and a plurality of non-extensible The pneumatic safety tire is a side-reinforced pneumatic safety tire having a belt layer and a tread portion sequentially arranged to reinforce each, and also having an inner peripheral surface of the carcass ply layer of the sidewall or an annular reinforcing rubber layer between a plurality of carcass ply layers. An organic fiber having a core-sheath structure in which the organic fiber cord comprises a core portion and a sheath portion surrounding the core portion. A pneumatic safety tire, which is a cord formed by twisting raw yarns, wherein the core is made of polyester and the sheath is made of aliphatic polyamide. 2. The pneumatic safety tire according to claim 1, wherein the polyester is selected from the group consisting of polyethylene terephthalate and polyethylene naphthalate. 3. The pneumatic safety tire according to claim 1, wherein the aliphatic polyamide is selected from the group consisting of polyhexamethylene adipamide and polytetramethylene adipamide. 4. The weight ratio of core / (core + sheath) is 0.5.
The pneumatic safety tire according to claim 1, wherein the value is 0.9 to 0.9. 5. The pneumatic safety tire according to claim 1, wherein at least one down carcass layer is further disposed between the sidewall portion and an outer surface of the carcass layer.