JP2002105788A - Cord material and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cord material suitable for a carcass of a pneumatic tire, having a high strength and excellent in dimensional stability, and a pneumatic tire excellent in uniformity while maintaining traveling endurance. SOLUTION: This cord material is characterized by being formed with a polyester fiber and showing 4.5-6.5% intermediate elongation (M) under 1.98 (cN/dtex) load and its dry heat shrinkage (S) in a state of loading an initial weight of 50 g at 177 deg.C for 30 min, to satisfy the following formula: A+9.7<S (%)<A+10.5 [A=(0.17×M2)-(2.5×M)]. Its twisting coefficient is preferably 0.36-0.62. The pneumatic tire has at least a carcass ranging t its bead part forming as a toroidal state, and the carcass is formed by the above cord material. It is preferable that the one end of the carcass arranged as folded back by being wound up from the inside of the bead part to its outside, is positioned at further more central side of the tire than the outer circumference of the flange of a rim.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cord material which can be used in various fields as a reinforcing material, and is particularly suitable for a carcass of a tire, and a tire using the cord material for a carcass.

[0002]

2. Description of the Related Art Conventionally, nylon fiber cords, polyester fiber cords, and rayon fiber cords have been used for carcass plies in pneumatic radial tires of passenger cars. However, since the nylon fiber cord has a low elasticity, a high dry heat shrinkage, and a high creep, when the nylon fiber cord is used for a carcass ply, the nylon fiber cord is inferior in dimensional stability, flat spots are generated, and the amount used is reduced. There is a problem that we have to do it. On the other hand, since the rayon fiber cord has a lower strength than the nylon fiber cord, when the rayon fiber cord is used for a carcass ply, the amount of the rayon fiber cord must be increased, the tire weight increases, and the rolling resistance increases. However, there is a problem that various characteristics such as the above-mentioned characteristics are deteriorated. In addition, since the raw material is pulp, it may be difficult to obtain the raw material in the future. For this reason, polyester fibers that compensate for the disadvantages of both have been mainly used for carcass plies. However, in recent years, in pneumatic radial tires for passenger cars, it has been desired to satisfy various tire characteristics in a high-dimensional and well-balanced manner. Therefore, suppression of a decrease in vibration riding comfort and improvement in steering stability due to the above have become particularly important problems.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention is a cord material having high strength and excellent dimensional stability, which is particularly suitable for a carcass in a tire as a reinforcing material for rubber products and the like in various fields, and
It is an object of the present invention to provide a tire which is excellent in uniformity while maintaining running durability, and satisfies tire characteristics such as vibration riding comfort and steering stability in a well-balanced manner.

[0004]

In order to solve the above-mentioned problems,
As a result of intensive studies, the present inventors have obtained the following findings. That is,
The vibration riding comfort and the driving stability of a tire of a passenger car are greatly affected by the uniformity of the tire. The uniformity of the tire is particularly greatly affected by the physical properties, length, weight distribution, and the like of the carcass ply wound and arranged in the tire radial direction. However, since the carcass ply has the above-mentioned problem when the nylon fiber cord or the rayon fiber cord is used,
Instead, vibrations generated during high-speed running can be suppressed by using a polyester fiber cord having high strength and excellent dimensional stability for the carcass ply of the tire. In the polyester fiber cord, when the intermediate elongation is increased, the heat shrinkage is reduced, and when the intermediate elongation is reduced, the heat shrinkage is increased. When the relationship between the two is within a predetermined range, high strength and excellent dimensional stability are obtained. When this is used for a carcass in a tire, the value of a radial force variation (hereinafter, referred to as “RFV”) indicating tire non-uniformity (collapse from roundness) can be reduced, and tire non-uniformity can be reduced. It is a finding that a tire excellent in various tire characteristics such as vibration riding comfort and steering stability caused by the vibration can be obtained.

[0005] The present invention is based on the above findings by the present inventor, and the means for solving the above problems are as follows. That is, <1> formed of polyester fiber, and 1.98 (cN
/ Dtex) Intermediate elongation (M) under load is 4.5 to 4.5
The cord material is 6.5%, and has a dry heat shrinkage (S) satisfying the following expression when an initial load of 50 g is applied at 177 ° C. for 30 minutes. A + 9.7 <S (%) <A + 10.5 where A = (0.17 × M ² ) − (2.5 ×
M). <2> The twist coefficient K is 0.36 to 0.62.
1>.

[0006]

(Equation 2)

However, in the above formula, N is the number of twists (twice / 10
cm). D is the total number of displayed decitex (dte
x). ρ represents specific gravity. <3> The cord material according to <1> or <2>, wherein the polyester fiber is a polyethylene terephthalate fiber. <4> The cord material according to any one of <1> to <3>, which is used for a carcass of a tire. <5> A tire comprising at least a carcass connected in a toroidal shape at a bead portion, the carcass being formed of the cord material according to any one of <1> to <4>. It is. <6> The above-described <6>, wherein one end of the carcass wound up from the inside of the bead portion and folded back outward when incorporated into the rim is located closer to the tire center than the outer periphery of the flange of the rim. Tires.

[0008] The cord material according to <1>, which is formed of polyester fiber, has an intermediate elongation (M) of 4.5 to 6.5% under a load of 1.98 (cN / dtex),
The dry heat shrinkage (S) in a state where an initial load of 50 g is applied at 177 ° C. for 30 minutes is represented by the following equation: A + 9.7 <
S (%) <A + 10.5 (where A =
^{(0.17 × M 2) - (} 2.5 × M), a. ), Meet. Since the cord material is made of polyester fiber, it has excellent mechanical properties such as rigidity, thermal properties, etc., and can be suitably used as a reinforcing material for rubber products in various fields, particularly as a carcass in tires. As in the case of the nylon fiber cord, the dimensional stability is inferior, there is no problem that the flat spot occurs and the use amount has to be reduced, and as in the case of the rayon fiber cord, the use amount has to be increased. There is no problem that tire weight increases and various characteristics such as rolling resistance are reduced.
The intermediate elongation (M) is 4.5 to 6.5%, the heat shrinkage at this time is appropriate, and the dry heat shrinkage (S)
Satisfies the above equation, the amount of expansion and contraction of the cord material during vulcanization is moderate, and the RFV is small. For this reason, the cord material can be particularly suitably used as a carcass in a tire, and a tire using the cord material for a carcass has excellent tire characteristics such as vibration riding comfort and steering stability.

[0009] The cord material according to <2>, wherein
>, The twist coefficient K is 0.36 to 0.62. In this case, when the cord material is used for a carcass in a tire, the tire has excellent running durability.

[0010] The cord material according to <3>, wherein
> Or <2>, the polyester fiber is a polyethylene terephthalate fiber. For this reason, the cord material is excellent in dimensional stability, strength, and manufacturability. Therefore, the cord material can be suitably used as a reinforcing material in various fields, particularly as a carcass in a tire.

[0011] The cord material according to <4>, wherein the <1>
<3> is used for a carcass of a tire. In this case, the tire is excellent in uniformity while maintaining running durability, and is excellent in vibration riding comfort and steering stability.

[0012] The tire according to <5> has at least a carcass connected in a bead portion in a toroidal shape, and the carcass is the cord material according to any one of <1> to <4>. It is characterized by being formed by. In this case, the carcass is excellent in dimensional stability, high in strength, and high in performance. Therefore, a tire using the cord material for the carcass has excellent uniformity while maintaining running durability, and has excellent vibration riding comfort. Excellent in handling and steering stability.

The tire according to <6>, wherein the tire according to <5>
In the above, when assembled into the flange of the rim, one end of the carcass wound up from the inside of the bead portion and folded outward is positioned closer to the center of the tire than the outer periphery of the flange of the rim. For this reason, the tire is particularly excellent in running durability.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Cord Material) The cord material of the present invention is formed of polyester fiber and has a thickness of 1.98 (cN / d).
tex) The intermediate elongation (M) under load is 4.5-6.
5%, and the dry heat shrinkage (S) under the condition of applying an initial load of 50 g at 177 ° C. for 30 minutes must satisfy the following expression. A + 9.7 <S (%) <A + 10.5 where A = (0.17 × M ² ) − (2.5 ×
M).

When the cord material satisfies the relationship between the intermediate elongation (M) and the dry heat shrinkage (S), the relationship between the two in the cord material is shown in FIG. This is a case where the indicated locus is included in the hatched portion. The cord material of the present invention included in the hatched portion has high strength and excellent dimensional stability. When the cord material is used for a carcass in a tire, since heat shrinkage from the time of vulcanization where heat and tension are applied to the time after post cure inflation can be reduced, the cord material is used in a tire. It can be particularly suitably used for carcass.

On the other hand, in the case of a cord material used for a conventional tire carcass, the locus indicating the relationship between the intermediate elongation (M) and the dry heat shrinkage (S) is indicated by oblique lines in FIG. It is not included in the portion and is located above the shaded portion. In this case, the RFV of the cord material is large, and a tire using the cord material for a carcass is inferior in tire characteristics such as vibration riding comfort and steering stability.

As described above, the intermediate elongation (M) needs to be 4.5 to 6.5%, and it is necessary to set the intermediate elongation (M) to 5.0 to 6.5.
0% is preferred. When the intermediate elongation (M) is less than 4.5%, the heat shrinkage of the cord material is large, and when the cord material is used for a carcass in a tire, the RFV becomes large, resulting in poor uniformity and vibration. Ride comfort,
On the other hand, if it exceeds 6.5%, the cord material has a large amount of elongation during post-cure inflation after vulcanization of the cord material. When used for
The FV is large, the uniformity is inferior, the riding comfort and the steering stability are inferior.

The intermediate elongation (M) is JIS L 10
Tensile at room temperature (25 ° C. ± 2 ° C.) according to No. 17, 1.9
It is obtained by measuring the elongation (%) under a load of 8 (cN / dtex). Note that “dtex” here
Is the value of "dtex" of the original yarn before twisting.

As described above, the dry heat shrinkage (S) is A
+9.7 <S (%) <A + 10.5 (where,
A = (0.17 × M ² ) − (2.5 × M). When the dry heat shrinkage (S) is (A)
+9.7) or less, the cord material has low strength, is inferior in heat deterioration resistance and compression fatigue resistance, is not suitable for carcass, etc., and a tire using the cord material for carcass has poor running durability. On the other hand, if it is more than (A + 10.5), the heat shrinkage of the cord material is large, and if the cord material is used for a carcass in a tire, the RFV becomes large, the uniformity is poor, and the riding comfort is poor. Poor handling stability.

The dry heat shrinkage (S) is determined, for example, by allowing the cord material to stand at 177 ° C. for 30 minutes in an oven with an initial load of 50 g applied thereto, and then heat shrinking the cord material. The measured length can be measured, divided by the length of the cord before heat shrinkage, and calculated as a percentage (%) of the value.

The cord material is obtained as a twin-twist raw cord by subjecting at least polyester fiber to a primary yarn and twist-twisting and twisting the polyester fiber. If necessary, an adhesive or the like may be applied to the surface of the cord. It is applied and heat-treated.

The polyester fiber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyethylene terephthalate fiber, polyethylene naphthalate fiber, and polybutylene terephthalate fiber. Among these, polyethylene terephthalate fibers spun at a higher speed and with a higher stress than usual are preferable in terms of cost performance. These polyester fibers may be used alone or in combination of two or more.

The number of decitex of the polyester fiber as the raw yarn is about 500 to 3000 dtex, preferably 1000 to 2500 dtex.

Twist coefficient K of the cord material represented by the following formula:
Is preferably 0.36 to 0.62, and 0.40 to 0.60.
0.55 is more preferred. The twist coefficient K is 0.36
If it is less than 1, it is not suitable for a tire carcass, and a tire using the cord material for a carcass may have poor running durability. If it exceeds 0.62, it is not suitable for a tire carcass, Tires using a material for a carcass may have poor running durability.

[0025]

(Equation 3)

However, in the above formula, N is the number of twists (twice / 10
cm). D represents the total number of displayed decitex. ρ
Represents specific gravity.

The total number of decitex D in the cord material
Is preferably 1000 to 6000 dtex, and 2
000-5000 dtex is more preferred. When the total decitex number D in the cord material is less than 1000 dtex, the number of shots may be too small and the number of shots may be too dense. is there.

The adhesive is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a two-component reactive adhesive and a one-component non-reactive adhesive. An RFL (resorcin-formalin resin-latex) adhesive is preferable because the adhesiveness between the rubber and the rubber can be improved.

The method for applying the adhesive is not particularly limited, and a known method can be employed. Examples thereof include a dipping method, a bar coating method, a kneader coating method, a curtain coating method, a roller coating method, and the like. Spin coating, and the like.

Examples of the heat treatment include a drying treatment, a heat setting treatment (heat setting treatment) and a normalizing treatment, and these heat treatments are preferably applied in this order. These heat treatments may be performed continuously or batchwise, but are preferably performed continuously from the viewpoint of production efficiency. As a method of continuously performing the heat treatment,
There is no particular limitation, and it can be appropriately selected according to the purpose. For example, heating furnaces for performing the above-described processes are continuously arranged, and the inside of the heating furnace (zone) is continuously performed using a conveyor or the like. For example, a method of allowing the gas to pass therethrough.

The heat treatment conditions, tension conditions and the like in the drying treatment, the heat setting treatment and the normalizing treatment are appropriately selected such that the intermediate elongation and the dry heat shrinkage ratio of the obtained cord material satisfy the above relation. be able to.

When the cord material is used for a carcass in a tire, the rubber is a rubber which is coated on the surface of a plurality of cord materials arranged in parallel.
There is no particular limitation, and it may be a natural rubber, a synthetic rubber, or a blend thereof, and may be appropriately selected from known rubbers according to the purpose.

When the cord material is used as a carcass in a tire, the width and the like of the carcass are not particularly limited, and can be appropriately selected according to the use and the like. In addition, the number of the cord materials to be driven into the carcass is about 30 to 80 cords / cm,
Book / cm is preferred.

The cord material can be suitably used as a reinforcing material for rubber products and the like in various fields, and can be particularly preferably used for the following carcass of the tire of the present invention.

(Tire) The tire of the present invention has at least a carcass connected in a toroidal shape at the bead portion, except that the carcass is formed of the cord material of the present invention. The structure, size, material, and the like are not particularly limited, and a known configuration can be appropriately employed. The tire of the present invention can be used as a pneumatic tire filled with a gas, and examples of the gas include air and nitrogen.

Examples of the structure other than the carcass of the tire include a pair of bead portions, a belt layer for clinching a crown portion of the carcass, a tread, and the like.

The tire may be a radial tire or a bias tire, but is preferably a radial tire.

In the tire, when the tire is mounted on a rim, it is preferable that one end of the carcass wound up from the inside of the bead portion and folded is located closer to the center of the tire than the outer periphery of the rim. . In this case, the tire is preferable because it has excellent running durability.

The tire of the present invention is excellent in uniformity while maintaining running durability, and is excellent in vibration riding comfort, steering stability, etc., so that it can be suitably used as a tire for a passenger car, which has many opportunities for high-speed running. it can.

[0040]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples.

(Example 1) The tire (pneumatic radial tire) in Example 1 has a pair of beads fitted to a rim flange, and is folded around the beads from the inside to the outside of the tire and locked. A carcass, a bead filler contained in the carcass folded around the bead,
A tread portion located at a crown portion of the carcass, a sidewall portion having the beads embedded therein, an inner liner layer disposed inside the carcass, a belt layer disposed inside the tread portion, and the belt A cap ply layer disposed on the outer peripheral side of the layer and over the entire width thereof.

The tire (pneumatic radial tire) in Example 1 has a tubeless structure of 205 / 65R15, and is manufactured under vulcanization conditions of 170 ° C. × 13.
Min, post cure inflation condition internal pressure 2.5
The test was performed at kg / cm ² for 26 minutes.

The carcass of the tire has 1100
One piece using a polyester (polyethylene terephthalate) fiber cord having a dtex / 2 (1100 decitex two twists) twist number (primary twist x upper twist) of 47 x 47 (times / 10 cm), and the number of shots is 55.0. Book / 5cm
Was used. The carcass was arranged in a direction substantially perpendicular to the tire circumferential direction.

The polyester fiber cord is the cord material of the present invention, and details of its intermediate elongation (M) and dry heat shrinkage (S) are as shown in Table 1. The carcass is obtained by pulling the polyester fiber cord with rubber (a coating rubber mainly composed of natural rubber).

The polyester fiber cord as the cord material used for the carcass was obtained as follows. That is, a melt of a polyester (polyethylene terephthalate) having a sulfuric acid relative viscosity of 3.2 is spun at 2500 m / min or more, which is a take-up speed higher than usual,
Thereafter, by performing appropriate heat stretching, relaxation, cooling, and the like at a heat treatment temperature of 235 ° C., a polyester (polyethylene terephthalate) yarn of 1100 dtex was obtained. Next, using a ring twisting machine, 47 × 47
The number of twists of 10 cm was applied to obtain a twin twisted cord of 1100 dtex / 2. And this twin twist raw cord is
Respectively immersed in a liquid epoxy aqueous solution and a two-component RFL (resorcin-formalin resin-latex) aqueous solution adhesive,
It was dried and heat-treated. Drying process (drying zone)
The temperature at this time was 140 ° C., and the processing time was 120 seconds. The temperature during the heat treatment was 235 ° C., and the processing time was 90 seconds. The cord tension during heat setting was 1.0 g / d.

In the tire, as a belt layer, two steel cord belts each having a structure of 1 × 3 × 0.24 mm (element wire diameter: 0.3 mm) are arranged.
25 ° left and right with respect to the circumferential direction.
The thing of 0 / 5cm was used. The belt layer 16 has steel fiber cords arranged at an inclination angle of 25 ° with respect to the tire circumferential direction (equatorial plane of the tire).
The codes were superimposed so that they crossed in different directions.

For the cord material used for the carcass of the tire (pneumatic radial tire) in Example 1, the intermediate elongation and the dry heat shrinkage (%) were evaluated as follows, and the uniformity and running of the tire were evaluated. The durability was evaluated as follows. The results are shown in Table 1. In the tire, one end of the carcass wound up from the inside of the bead portion and folded is positioned closer to the center of the tire than the outer periphery of the rim when the tire is mounted on the rim.

<Measurement of Intermediate Elongation (M) of Cord Material> A carcass with surface rubber attached was cut out from the tire, and excess rubber pieces on the surface were scraped off as much as possible. Pull at room temperature (25 ° C. ± 2 ° C.) by an autograph according to 1017-1998.
The elongation (%) under (cN / dtex) load was measured. In addition, here, "dtex" used the value of "dtex" of the original yarn before twisting.

<Measurement of Dry Heat Shrinkage (S) of Cord Material> A carcass with the surface rubber attached was cut out from the tire, and excess rubber pieces on the surface were scraped off as much as possible, followed by an oven. In a state in which a 50 g initial load was applied to the cord material of the carcass, the material was left at 177 ° C. for 30 minutes to be thermally shrunk, and the length of the thermally shrunk was measured. The value was calculated as a percentage (%) of the value.

<Tire uniformity (RFV value)
Measurement> Measured in accordance with the automotive standard JASO C 607 “Method for testing uniformity of automotive tires”.

<Measurement of running durability of tire> Using a drum testing machine having a drum surface of 1.707 m and a smooth drum surface, the ambient temperature was controlled to 30 ± 3 ° C.
The tire was run under the conditions of 9.4 kPa and a load of 12.74 kN until a failure occurred. The longer the running distance, the better the running durability. The results are indexed assuming that the running durability of the tire of Comparative Example 1 is "100", and those of less than 60 are represented by "x", those of 60 or more and less than 100 are represented by "△", and those of 100 or more are represented by "○""

(Examples 2 to 10 and Comparative Examples 1 to 5) The procedure of Example 1 was repeated, except that the intermediate elongation and the dry heat shrinkage of the cord material were different as shown in Table 1.
The results are shown in Table 1. In each tire, one end of the carcass wound up and folded back from the inside of the bead portion is located closer to the center of the tire than the outer periphery of the rim when the tire is mounted on the rim (below the rim line). )
Table 1 shows whether the tire is located on the outer peripheral side of the tire (on the rim line).

[0053]

[Table 1]

From the results shown in Table 1, it is clear that the tire of the present invention using the cord material of the present invention as a carcass has a small RFV while maintaining the running durability as compared with the tire of the comparative example. .

[0055]

According to the present invention, it is possible to solve the above-mentioned problems in the prior art, and it is suitable as a reinforcing material for rubber products in various fields, particularly for a carcass in a tire, and has high strength and excellent dimensional stability. It is possible to provide a tire having excellent uniformity while maintaining running durability and a good balance of tire characteristics such as vibration riding comfort and steering stability.

[Brief description of the drawings]

FIG. 1 is a view showing a relationship between an intermediate elongation and a heat shrinkage of a cord material of the present invention used for a carcass of a tire.

Claims (6)

[Claims] 1.98. 1.98 made of polyester fiber
(CN / dtex) an intermediate elongation (M) under a load of 4.5 to 6.5% and at 177 ° C for 30 minutes;
A cord material having a dry heat shrinkage (S) satisfying the following formula under an initial load of 50 g. A + 9.7 <S (%) <A + 10.5 where A = (0.17 × M ² ) − (2.5 ×
M). 2. The cord material according to claim 1, wherein the twist coefficient K is 0.36 to 0.62. (Equation 1) Here, in the above formula, N represents the number of twists (twice / 10 cm). D represents the total number of displayed decitex (dtex).
ρ represents specific gravity. 3. The cord material according to claim 1, wherein the polyester fiber is a polyethylene terephthalate fiber. 4. The tire according to claim 1, which is used for a carcass of a tire.
4. The cord material according to any one of items 1 to 3. 5. A tire comprising at least a carcass connected to a bead portion in a toroidal shape, wherein the carcass is formed of the cord material according to any one of claims 1 to 4. 6. The carcass according to claim 5, wherein when assembled into the rim, one end of the carcass wound up from the inside of the bead portion and turned outward is located closer to the center of the tire than the outer periphery of the flange of the rim. Tires.