JP2002307908A - Radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radial tire of high performance effectively suppressing the change (deformation) of tire shape during use and having excellent high-load durability and driving stability which are well-balanced. SOLUTION: In this radial tire provided with a radial carcass and a belt arranged at the outer periphery of the carcass, a carcass cord constituting the carcass comprises polyolefine ketone formed of the repetition unit of a carbonyl part and an olefine part, and the elastic modulus of the carcass cord is 400-1000 N/mm<2> to attain the purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire, and more particularly to a high-performance radial tire excellent in high load durability and steering stability.

[0002]

2. Description of the Related Art Conventional pneumatic radial tires generally use organic fiber cords such as rayon, nylon and polyester as ply cords in a carcass. All of these organic fiber cords are
The initial tensile resistance specified in SL 1017-1995 (chemical fiber tire cord test method) is not a high value.

[0003] Therefore, in a pneumatic tire using these organic fiber cords as a ply of a carcass, the organic fiber cords are liable to elongate and vary in the amount of elongation during use, and the tire shape changes (deformation). There is a possibility that. Therefore, there is a possibility that the running performance may be reduced, and there is a problem that the device cannot be used under severe conditions such as an ultra-high speed.

[0004] The fiber constituting the cord is twisted from the viewpoint of imparting sufficient fatigue resistance to the cord that can withstand use under severe conditions such as ultrahigh speed. However, the value of the initial tensile resistance is relatively high, aramid, carbon,
In the case of so-called ultra-high elasticity fibers such as glass fibers, the elongation increases due to the effect of twisting, and the initial tensile resistance decreases. For this reason, the pneumatic tire using these ultra-high elasticity fiber cords has a problem that steering stability is reduced during use. In addition, a pneumatic tire using a cord made of ultra-high elasticity fiber generally has a problem that it is inferior in high load durability.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention provides a high-performance radial tire that effectively suppresses changes (deformation) in the tire shape during use, is excellent in high load durability and steering stability, and has a good balance between them. The purpose is to do.

[0006]

As a result of intensive studies, the present inventor has found that the following problems can be solved by the following invention. That is, <1> a radial tire including a radial carcass extending in a toroidal shape between bead cores embedded in a pair of beads, and a belt disposed on the outer periphery of the carcass, wherein the carcass cord constituting the carcass is as follows. A repeating unit represented by the formula I (formula I
In the formula, A represents a divalent olefin residue, and in the repeating unit, all A may be the same or different from each other), and have 0.3 g of the carcass cord. / Dtex and 0.6g
/ Dtex and the initial tensile resistance expressed using the difference in elongation at each stress and the stress difference are 400 to 100.
0N / mm ² , and the carcass cord was obtained by a heat treatment time of 40 to 120 seconds in the heat setting zone and the normalizing zone, and the processing condition in the heat setting zone was such that the temperature range was (Tm-13) ~
(Tm-5) ° C (where Tm represents the crystal melting point of the polyolefin ketone) and the treatment tension is 0.4 to 1.
The processing conditions in the normalizing zone are 8 g / dtex, and the temperature range is (Tm-13) to (Tm-5).
° C (where Tm represents the crystal melting point of the polyolefin ketone) and the treatment tension is 0.2 to 0.9 g / dte.
A radial tire that is x.

[0007]

Embedded image

<2> In the above item <1>, A is preferably an ethylene unit. <3> In the above item <1> or <2>, the elongation at 0.02 N / dtex stress of the carcass cord is more than 3.5% and not more than 6.0%, and the elongation at break is 11% or more. There should be.

<4> A radial tire including a radial carcass extending in a toroidal shape between bead cores embedded in a pair of beads, and a belt disposed on the outer periphery of the carcass, wherein a carcass cord constituting the carcass is provided. A repeating unit represented by the following formula I (formula I
In the formula, A represents a divalent olefin residue, and in the repeating unit, A may be the same or different from each other), and contains 0.3 g of the carcass cord. / Dtex and 0.6g
/ Dtex and the initial tensile resistance expressed using the difference in elongation at each stress and the stress difference are 400 to 100.
A radial tire of 0 N / mm ² .

<5> In the above item <4>, the carcass cord may include a heat set zone and a normalizing zone.
The heat treatment time in the zone is obtained by 40 to 120 seconds, and the processing conditions in the heat set zone are as follows: temperature range (Tm-13) to (Tm-5) ° C (where Tm represents the crystal melting point of polyolefin ketone). ) And the processing tension is 0.4 to 1.8 g / dtex, and the processing conditions in the normalizing zone are such that the temperature range is (Tm−
13) to (Tm-5) ° C (where Tm represents the crystal melting point of the polyolefin ketone), and the treatment tension is 0.
It is preferably 2 to 0.9 g / dtex.

<6> In the above item <4> or <5>,
A is preferably an ethylene unit. <7> In any one of the above items <4> to <6>, the elongation at 0.02 N / dtex stress of the carcass cord is more than 3.5% and 6.0% or less, and the breaking elongation is 11%. %.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A radial tire according to the present invention is a radial tire including a radial carcass extending in a toroidal shape between bead cores embedded in a pair of beads, and a belt disposed on the outer periphery of the carcass. The radial tire of the present invention is not particularly limited with respect to other configurations, materials, shapes, sizes, etc., excluding the carcass and / or the belt, and can be appropriately selected according to the purpose. It can be configured similarly.

Further, as the radial tire of the present invention, for example, a pneumatic radial tire in which the inside is filled with air can be cited, but is not limited thereto. That is, the radial tire of the present invention can be a radial tire filled with various gases therein, and may be, for example, a tire filled with only nitrogen as a gas, and various mixing ratios with air as a gas. It may be one in which nitrogen is added.

The radial carcass comprises a carcass cord, and the carcass cord comprises a polyolefin ketone comprising a repeating unit represented by the above formula I. Hereinafter, the polyolefin ketone, the polyolefin fiber, and the fiber cord having the fiber will be described in detail.

In the above formula I, A represents a divalent olefin residue and is a part derived from an olefin monomer.
A is bound to the carbonyl moiety, as is apparent from formula I. That is, the polyolefin ketone is a polymer in which carbonyl moieties and moieties derived from olefin monomers are alternately arranged. In the polyolefin ketone,
The part derived from the olefin-based monomer, that is, A, may be one type or two or more types. If one type, the polyolefin ketone is a homopolymer, and if two or more types, the polyolefin ketone can be a copolymer.

The case of a copolymer will be described briefly. For example, when A1 is an ethylene group, A2 is a propylene group, and the polyolefin ketone includes A1 and A2, the polyolefin ketone is a first repeating unit of -CO-A1- and a second repeating unit of -CO-A2-. And a copolymer containing That is, when the polyolefin ketone of the present invention is a copolymer,
Various copolymers such as random copolymers and block copolymers are included.

In the above, examples of the ethylene group and the propylene group have been mentioned as A. In addition, various olefin monomers, that is, A can be mentioned. For example, butene, pentene, hexene, heptene, octene, nonene, decene, dodecene, styrene, methyl acrylate, methyl methacrylate, vinyl acetate, undecenoic acid, undecenol, 6-chlorohexene, N-vinylpyrrolidone, and the diethyl of sulfonylphosphonic acid Esters and the like can be mentioned.

Of these, ethylene is preferred from the viewpoints of mechanical properties and heat resistance. That is, the polyolefin ketone of the present invention is preferably a homopolymer or copolymer in which the part A derived from an olefin monomer is an ethylene unit (—CH ₂ —CH ₂ —). In the case of a copolymer, the molar ratio of the ethylene part (—CH ₂ —CH ₂ —) to another olefin part (ethylene part / other olefin part) is preferably 4/1 or more, and 8/1 or more. Is more preferable. When the molar ratio is 4/1 or more, the melting point of the polyolefin ketone is increased, that is, the polyolefin ketone tends to have heat resistance. Also,
It is preferable that the molar ratio is 8/1 or more because the heat resistance and mechanical performance of the polyolefin ketone are more excellent.

The process for producing the polyolefin ketone used in the present invention is described, for example, in EP-A-12196.
Nos. 5,213,671 and 2,229,408; U.S. Pat. No. 3,914,391; and U.S. Pat.
No. 3 and the like, which are included in the present invention by reference.

The degree of polymerization of the polyolefin ketone is 60 ° C.
Of the solution (LVN) measured in m-cresol. The LVN is 1.0 to 10.0 d
1 / g, preferably 1.2 to 5.0 dl / g, and more preferably 1.3 to 4.0 dl / g. When the melt viscosity (LVN) is within the above range, the mechanical strength, melt viscosity at the time of fiberization, solution viscosity and spinnability of the finally obtained cord tend to be good.

The above-mentioned polyolefin ketone is fiberized to prepare a polyolefin ketone fiber. The preparation method is not particularly limited, and may be various methods such as a melt spinning method and a solution spinning method.

When the melt spinning method is used, for example, a method described in JP-A-1-124617 can be used. That is, the polyolefin ketone is reduced to at least (Tm + 2
0), preferably melt spinning at (Tm + 40) ° C, then up to (Tm-10) ° C, preferably (Tm-40)
The polyolefin ketone fiber can be easily produced by drawing at a drawing ratio of preferably 3 times or more, more preferably 7 times or more (here, Tm represents the crystal melting point of the polyolefin ketone). .

In the case of the solution spinning method, see, for example,
The method described in JP-A-112413 can be used. That is, a polyolefin ketone is added to, for example, hexafluoroisopropanol, m-cresol, etc.
It is dissolved at a concentration of 20% by weight, preferably 0.5 to 10% by weight, and extruded from a spinning nozzle to form a fiber.
Then, toluene, ethanol, isopropanol, n-
After removing the solvent in a non-solvent bath such as hexane, isooctane, acetone, methyl ethyl ketone, or the like, preferably an acetone bath, washing is performed to obtain a spun yarn, and (Tm-10
0) to (Tm + 10) ° C, preferably (Tm-50)
By stretching at Tm ° C., a polyolefin ketone fiber can be easily produced.

Polyolefin ketone fibers have higher strength, higher elastic modulus and better dimensional stability than polyethylene terephthalate (PET) fibers, and have less heat shrinkage than nylon fibers, and do not have heat shrinkage like rayon fibers. The water resistance stability is not bad, and at the same time, the adhesiveness with rubber is excellent,
Also excellent in amine resistance deterioration in rubber.

The polyolefin ketone fiber may contain an antioxidant for the purpose of imparting sufficient durability to heat, oxygen and the like. If necessary, known additives such as a matting agent, a pigment, and an antistatic agent may be contained.

The polyolefin ketone fiber (polymer filament) thus obtained usually has a tensile strength of at least 8.83 cN / dtex, and
It is preferably at least 9 cN / dtex. The initial elastic modulus is usually at least 88.3 cN / dtex, preferably at least 105.9 cN / dtex, more preferably at least 132.4 cN / dtex.

The fiber cord may be formed from one polyolefin ketone fiber or may be formed from two or more polyolefin ketone fibers. For example, when forming a fiber cord from two or more polyolefin ketone fibers, the polyolefin ketone fibers are twisted,
Next, two or three of them are combined and twisted in the reverse direction to obtain a twin-twisted raw cord.

When the fiber cord is a twin-twisted cord, the twist coefficient R represented by the following formula is preferably 1600 to 2800.

R = N × √0.9D In the formula, N represents the number of twists of the cord (twice / 10 cm).
Represents the total display dtex number of the code. When the twist coefficient R is within the above numerical range, the fiber cord has an appropriate convergence, and tends to improve durability.

The fiber cords are arranged, for example, in parallel to form a ply, and a carcass is formed. That is, for example, a fiber cord obtained as a twin-twisted raw cord is woven into fine wefts such as cotton and polynosic and a woven fabric, and then an adhesive is applied thereto, followed by drying, heating and tensioning to obtain a ply that has been subjected to a dip treatment. Get. Then, a carcass is formed by embedding this in the rubber matrix layer.

Adhesion between the fiber cord and the rubber matrix,
Alternatively, the bonding between the ply and the rubber matrix can be performed by a known method as described below. For example, a two-bath in which a fiber cord is treated with a first liquid containing an epoxy compound or a blocked isocyanate compound, and then treated with a second liquid (RFL liquid) containing resorcinol, formalin, various latexes, caustic soda and / or aqueous ammonia. One-bath type bonding method of treating with a mixture of a liquid called N3 generated from triallyl cyanurate, resorcin, formalin, and aqueous ammonia, and an RFL liquid; p-chlorophenol; A reaction product mainly composed of 2,6-bis (2 ', 4'-dihydroxyphenylmethyl) -4-chlorophenol formed from formalin, and a so-called PEXUL comprising resorcinol, formalin and aqueous ammonia. A one-bath type bonding method in which a liquid called a liquid is treated with a liquid mixed with an RFL liquid;
No. 72, etc., a one-bath type bonding method in which a polyhydric phenol polysulfide, a condensate of resorcinol and formalin, and a liquid obtained by mixing an RFL liquid with a liquid obtained by aging under alkaline conditions; It can be carried out.

As a heat tension treatment for obtaining a ply, a heat setting zone and a normalizing zone are preferably provided. The heat treatment time in the zone is 4
It is good to be 0 to 120 seconds, preferably 40 to 100 seconds, more preferably 40 to 80 seconds.

In the heat setting zone, when the crystal melting point of polyolefin ketone is represented by Tm, the temperature range is (Tm-13) to (Tm-5) ° C., preferably (Tm
m-10) to (Tm-5) ° C. Further, the treatment tension is 0.4 to 1.8 g / dtex, preferably 0.6 to 1.8 g / dtex. Also,
The condition in the normalizing zone is that the temperature range is (T
m-13) to (Tm-5) C, preferably (Tm-1).
0) to (Tm-5) ° C. Further, the treatment tension is 0.2 to 0.9 g / dtex, preferably 0.1 g / dtex.
It is preferably 3 to 0.9 g / dtex.

The obtained ply has an initial tensile resistance of
400 to 1000 N / mm², Preferably 500 to 10
00N / mm², More preferably 700 to 1000 N /
mm ²It is good. Here, the initial tensile resistance E
_fCan be represented by the following equation A.

E _f = 9 × ρ × ｛(ΔF / ΔE _L ) × 10
00 × 100 / 0.9D｝ Equation A. In formula A, D:
Total fineness (dtex), ΔF: stress difference (in the present invention, unless otherwise specified, 0.3 g / dtex and 0.6 g / dtex)
stress difference from dtex), ρ: fiber density (g / cm ³ ),
ΔE _L : difference in elongation at the time of two stresses (in the present invention,
0.3g / dtex and 0.6g / dte unless otherwise specified
x (elongation difference at each stress).

The fiber cord preferably has the following characteristics. That is, the elongation at 0.02 N / dtex stress is more than 3.5% and not more than 6.0%, preferably more than 3.5% and not more than 4.5%. The breaking elongation of the fiber cord is 11% or more, preferably 12 to 15%.

The carcass thus obtained may be used as it is, or may be used after being cut into appropriate dimensions. The carcass may have only one layer, but a plurality of layers, usually two to three layers, may be used in an overlapping manner. When a plurality of layers are used, at least one layer (1
In the case of a layer, the one layer) is usually folded back around the bead ring from the inside of the tire to the outside (axially outside) and locked. When a plurality of layers are used, for example, in the case of a two-layered up-down structure, a flipper or chafer arrangement commonly used for protection corresponding to folding around the bead core of the upper layer (up ply) and reinforcement of the bead portion may be employed.

The radial tire of the present invention includes a carcass including a ply having the above-described fiber cord, for example, a ply in which the above-described fiber cords are arranged in parallel.
The carcass is arranged in combination with a belt.

For example, as a belt to be combined with a carcass including a ply having the above-described fiber cord, 1 × 5 ×
Two steel cords having a diameter of 0.23 mmφ and those arranged inside the tread can be exemplified. In addition, caps, layers, and the like are appropriately arranged on the outer periphery of the belt. These include, for example, those based on 66 nylon 1260D / 2 cords.

[0040]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

(Examples 1 to 3 and Comparative Examples 1 to 3) (Preparation of Carcass Cord) Raw yarn of polyolefin ketone (hereinafter sometimes abbreviated as “PK”) and polyethylene terephthalate (hereinafter “PET”) The raw yarn (which may be abbreviated in some cases) was first twisted, two of them were put together, and then twisted in the opposite direction to obtain a twin-twisted raw cord. Table 1 below shows the number of twists and the number of twists. After applying an adhesive to the obtained twin-twisted cord and drying it at 130 ° C. for 120 seconds, the fiber cord was subjected to a heat-set zone condition shown in Table 1 for 40 seconds and a normalizing zone condition for 40 seconds to give a fiber cord. Obtained. When the initial tensile resistance of the obtained fiber cord was measured, the value was as shown in Table 1.

[0042]

[Table 1]

Using the fiber cords obtained in Examples 1 to 3 and Comparative Examples 1 to 3, pneumatic radial tires having a tire size of 235/45 ZR17 having only one carcass ply were constructed. In each of the tires, the carcass was applied in an up-down arrangement at 1670 dtex / 2, and a normal steel cord was used as a reinforcing element for the belt. ) And 140
Two caps made of 0dtex / 2 6.6 nylon cord were used.

The obtained tires were evaluated for (1) tire high load durability and (2) tire operation stability. Each evaluation is described in detail below.

(1) High-load durability of tire The high-load durability was measured using a drum tester having a smooth drum surface made of steel and having a diameter of 1.707 m. Ambient temperature is controlled to 30 ± 3 ℃, rim size 8JJ × 17,
Under the conditions of a test internal pressure of 300 kPa and a load of 1300 kg,
The tire was run until a failure occurred. The longer the running distance, the higher the tire durability. Assuming that the traveling distance until the failure of the tire of Comparative Example 1 occurs is 100,
Other tires were standardized. The values are shown in Table 1.

A value greater than 100 indicates better. The running distance of the tire of Comparative Example 1 in this test exceeded 1000 km. Considering past performance, this mileage is not a level that is problematic in the market, but the longer the distance to the occurrence of a failure, that is, the greater the value in Table 1, the greater the safety margin. I understand.

(2) Driving Stability Driving stability was measured by mounting the obtained tire on a 3000 cc class sports-type car, and starting with 80 km / h.
The preliminary running was performed at the speed of 3 minutes. After that, 60-2
An actual vehicle feeling test was performed at a speed of 00 km / h, and (i) straight running stability, (ii) turning stability, and (ii)
1) Items such as i) rigidity and (iv) handling
A rating of 10 to 10 was given, and each item was averaged to obtain a rating of steering stability. The evaluation of steering stability was performed by two specialized drivers, the average of the scores of the two drivers was obtained, and the result of the tire obtained in Comparative Example 1 was standardized as 100. This value is shown in Table 1. The value of the "tire steering stability index" in Table 1 indicates that the larger the value, the more stable the steering.

As is clear from Table 1, the tires using the fiber cords of Examples 1 to 3 show high values in both high load durability and steering stability. On the other hand, Comparative Examples 1 to 3
Tires using carcass cords, especially Comparative Examples 2 and 3
Although the tire of No. 1 showed a high value in terms of durability, the steering stability was low. That is, the comparative example could not provide a tire satisfying both the high load durability and the steering stability.

[0049]

According to the present invention, a high-performance radial which effectively suppresses a change (deformation) in tire shape during use, is excellent in high load durability and steering stability, and has a good balance between them. Tires can be provided.

Claims (3)

[Claims] 1. A radial tire including a radial carcass extending in a toroidal shape between bead cores embedded in a pair of beads, and a belt disposed on an outer periphery of the carcass, wherein a carcass cord forming the carcass is provided. A repeating unit represented by the following formula I (in the formula I,
A represents a divalent olefin residue, and in the repeating unit, A has a polyolefin ketone consisting of all the same or different from each other), and 0.3 g / dtex and 0.6g
/ Dtex and the initial tensile resistance expressed using the difference in elongation at each stress and the stress difference are 400 to 100.
0 N / mm ² , and the carcass cord was obtained by a heat treatment time of 40 to 120 seconds in the heat setting zone and the normalizing zone. The processing conditions in the heat setting zone were such that the temperature range was (Tm−
13) to (Tm-5) ° C. (where Tm represents the crystal melting point of the polyolefin ketone), and the treatment tension is 0.
4 to 1.8 g / dtex, and the processing conditions in the normalizing zone are such that the temperature range is (Tm-13) to
(Tm-5) ° C (where Tm represents the crystal melting point of the polyolefin ketone), and the treatment tension is 0.2 to 0.
A radial tire having a weight of 9 g / dtex. Embedded image 2. The radial tire according to claim 1, wherein A is an ethylene unit. 3. The carcass cord of 0.02 N / dt.
The radial tire according to claim 1 or 2, wherein the elongation at the time of ex stress is more than 3.5% and not more than 6.0%, and the elongation at break is not less than 11%.