JPH09324377A - Tire cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tire cord, having a high elastic modulus, excellent in fatigue resistance, maneuvering stability when running at a high speed, reduction in fuel consumption, durability, reproducibility of quality, dimensional stability, low heat buildup properties and adhesion and useful as a carcass member, etc., by composing the tire cord of a specific polymeric filament yarn. SOLUTION: This tire cord comprises a polymeric filament yarn substantially composed of a recurring unit represented by the formula (A is a part derived from the same or different ethylenically unsaturated hydrocarbon polymerized through ethylenic bonds), having >=10.0g/denier tensile strength and >=120g/denier initial elastic modulus and composed of carbon monoxide and ethylene, etc., and has a bending stiffness of the cord within the range of 10-80g. Furthermore, the tire cord is suitable as a carcass member for a large-sized radial tire.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a tire core which is excellent in strength, elastic modulus and fatigue resistance, and which is excellent in handling stability, fuel consumption reduction, durability and quality reproducibility as a pneumatic tire at high speed running. Concerning

[0002]

2. Description of the Related Art Pneumatic tires are classified into three types, a via tire, a radial tire, and a belted bias tire, depending on the direction or arrangement of the cords. Two types, a radial tire and a belted bias tire, which have a belt effect on the belt, are available. It is said that the tire has good longitudinal stability. With the development of motorization, the reinforcing material for the belt portion of the radial tire and the belted bias tire has high strength, high elastic modulus, dimensional stability, impact resistance, adhesiveness, high compression elastic modulus, and low growth property. Although high stiffness is required, it is advantageous that the reinforcing material has a small specific gravity and a low price.

In recent years, the construction of highways has advanced, and belted bias tires and radial tires, which have good steering stability, have become widespread. Among them, radial tires using steel fiber as a belt member are excellent in steering. Attention is paid to the stability. However, since the radial tire emphasizes steering stability design, it is easy to directly pick up irregularities on the road surface, sacrificing riding comfort and habitability, and noise during running is also large. In other words, as a material
A tire with a good steering performance using a cord made of fiber as a reinforcing material has a rigid ground contact portion, and it is easy to directly pick up irregularities on the road surface.Therefore, a vehicle equipped with the tire can handle uneven road surfaces. It is known that when it runs, it vibrates violently and the ride comfort and habitability deteriorate.

The steel fiber cord is inherently rusty as compared with the organic fiber material, and its durability is insufficient. In addition, since the specific gravity of the tire itself is large, the tire itself becomes heavy, and the fuel consumption is large, which is an essential drawback.

Under these circumstances, it is not possible to use only a steel fiber cord as a belt member as a tire code capable of absorbing as much vibration as possible due to the unevenness of the road surface and improving riding comfort. However, it has been proposed to use aramid fibers in combination with steel fibers. However, due to the high price of aramid fibers used in combination and the difficulty in designing and manufacturing the tires associated with the use, it is the reality that they are limited to special tire applications.

On the other hand, among the textile cords, polyester cords having high modulus and dimensional stability are widely used, and rayon cords are also partially used. However, these materials are inferior in durability such as heat resistance in rubber, adhesiveness with rubber, fatigue resistance and the like, and therefore, application to a relatively large radial tire used under severe conditions is not preferable.

Therefore, there is a demand for the development of a material which has a modulus and dimensional stability comparable to those of polyester cords and which can be applied to a relatively large radial tire.

[0008]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a tire core having excellent steering stability at high speed and good durability.
Tire tires for carcass parts, especially for radial tires
A tire cord that substantially satisfies the required performance as a cord, that is, high strength, high elastic modulus, high modulus, dimensional stability, low heat generation property, low growth property, adhesiveness, and other properties required for a tire code. Is to provide the code.

[0009]

In order to achieve the above-mentioned object, the present inventor has selected a specific thermoplastic polymer as a fiber material.
It has been found that a tire cord using a fiber made of a material as a reinforcing material solves the above problems. That is, the present invention consists essentially of the repeating unit represented by the following general formula (1), has a tensile strength of 10.0 g / denier or more and an initial elastic modulus of 1
A cord composed of polymer filaments having a weight of 20 g / denier or more, and the bending hardness of the cord is 10
It can be achieved with tire cords in the range of ~ 80g.

Embedded image

In the present invention, the polymer constituting the polymer filament is composed of the repeating unit represented by the general formula (1), and the CO units in the polymer are substantially arranged alternately with the olefin-derived units. Copolymers. That is, it has a structure in which one olefin unit such as ethylene is located next to each CO unit in the polymer chain. The copolymer may be a true copolymer of carbon monoxide and one particular olefin, or alternatively a copolymer of carbon monoxide and two or more olefins.

The olefinic monomers which can be used in the polymer represented by the general formula (1) include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, dodecene, styrene,
Examples include methyl acrylate, methyl methacrylate, vinyl acetate, undecenoic acid, undecenol, 6-chlorohexene, N-vinylpyrrolidone, and diethyl ester of sulnylphosphonic acid, but mainly ethylene from the viewpoint of mechanical properties and heat resistance. Are preferred.

When ethylene and an olefin other than ethylene are used in combination, the molar ratio of ethylene to an olefin other than ethylene is preferably 4/1 or more. When it is less than 4/1, the melting point of the polymer is 200 ° C. or lower, and the heat resistance may be insufficient depending on the application. From the viewpoint of heat resistance and mechanical performance of the finally obtained nonwoven fabric, the molar ratio of ethylene to other olefinic monomer is more preferably 8/1 or more.

Corresponding alternating copolymers, catalysts and methods of preparation are described, for example, in EP-A-121965,
Known from 213671, 229408, and US Pat. No. 3,914,391. Also, the use of other known ethylene / CO copolymers that do not have alternating structures made using free radical catalysts are not considered in the present invention.

The degree of polymerization of the copolymer used in the present invention is
Solution viscosity (LVN) measured at 60 ° C in m-cresol
Is preferably in the range of 1.0 to 10.0 dl / g. If the LVN is less than 1.0 dl / g, the mechanical strength of the tire cord finally obtained may be insufficient, and it is more preferably 1.2 dl / g or more. On the other hand, when the LVN is more than 10.0 dl / g, the melt viscosity and the solution viscosity at the time of fiberizing may be too high and the spinnability may be poor, and it is more preferably less than 5.0 dl / g. From the viewpoint of the manufacturing processability of the fiber and the mechanical properties of the finally obtained tire cord, the LVN is 1.3 to.
More preferably, it is within the range of 4.0 dl / g.

The method for forming the fiber made of the above-mentioned copolymer is not particularly limited, but a melt spinning method or a solution spinning method is generally adopted. When the melt-spinning method is adopted, the polymer is melt-spun at a temperature of at least (T + 20) ° C., preferably (T + 40) ° C., and then at the maximum (T-
The desired fiber can be easily produced by a method of stretching at a temperature of 10) ° C., preferably (T-40) ° C., preferably a draw ratio of 3 times or more, more preferably a draw ratio of 7 times or more (where T is It is the crystalline melting point of the polymer).

When the solution spinning method is adopted, the polymer is, for example, hexafluoroisopropanol, m-, according to the method described in JP-A-2-112413.
Cresol etc. 0.25 to 20%, preferably 0.5
Dissolve at a concentration of -10%, extrude from a spinning nozzle to form fibers, and then remove and wash the solvent in a non-solvent bath of toluene, ethanol, isopropanol, n-hexane, isooctane, acetone, methyl ethyl ketone, etc., preferably an acetone bath. To obtain a spun raw yarn, and further (T-1
00) to (T + 10) ° C, preferably (T-50) to T
It can be stretched at 0 ° C. to finally obtain the desired fibers, where T is the crystalline melting point of the polymer.

It is preferable to add an antioxidant to the above-mentioned polymer for the purpose of imparting sufficient durability against heat, oxygen, etc., and if necessary, a matting agent,
Pigments, antistatic agents and the like can also be added. The polymer filaments thus obtained have a tensile strength of 1
It is necessary that the amount is 0.0 g / denier or higher, preferably 12.0 g / denier or higher, and the initial elastic modulus is 120 g / denier or higher, preferably 150 g / denier or higher. Since it has the characteristics of high strength and high elastic modulus, the reinforcing effect on the tire is increased, and it becomes possible to reduce the amount of fibers used for the tire or the number of plies, and to reduce the deformation amount of the tire and Since the recoverability of the tire is improved, the weight of the tire itself can be reduced and the tire can be manufactured with low fuel cost. Furthermore, the usefulness as a reinforcing material for radial tires and belted bias tires, which are required to have high-speed stability, durability, wear resistance, etc., can be greatly improved.

The tire cord of the present invention comprising such a polymer filament has a bending hardness of 10 to 80 g, preferably 20 to 60 g. Bending hardness of the cord is 10g
If it is less than the above range, the shape retention property of the woven slack of the cord is inferior, and the cord is likely to be disturbed when embedded in rubber. On the other hand, when the bending hardness is more than 80 g, the cord is too hard, so that the handling property in the process is deteriorated and the fatigue resistance of the cord may be deteriorated.

The cord of the present invention is a fiber obtained by the above-mentioned melt spinning method or solution spinning method (stretched yarn). The twist coefficient at this time is shown by the following equation, and the twist coefficient is 1300 to 2200, and particularly 1500 to
1800 is preferred. K = T√D (T is the number of twists, and D is the fineness of the raw cord.)

The smaller the twisting coefficient, the higher the modulus and the lower the shrinkage, but the fatigue resistance is lowered. Therefore, when the cord of the present invention is used as a tire carcass material, it is usually 2000-.
A twist factor of about 2200 is adopted.

The above-mentioned cord is woven as it is or after being woven into a swelling shape, and then an adhesive for tire cord, for example, RFL (resorcin-formalin-latex) liquid is preferably applied. The adhesion amount of the adhesive is 1 to 6% by weight, usually 2 to 5% by weight. Then, the adhesive is dried by passing through a heating furnace and then subjected to a tension heat treatment, which is usually performed continuously. These treatment conditions are not particularly limited as long as the bending hardness of the cord is within the above range.

The tire code of the present invention is suitable as a carcass material for a relatively large radial tire and has good steering stability,
A high performance tire with excellent durability can be obtained. Also, because it has a high modulus when used in conventional relatively large bias tires, the amount of deformation when the tire rotates under high load is small,
It is effective in reducing noise generated during driving.

[0023]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition, the physical-property value in an Example is a value measured by the following method. (1) Solution Viscosity (LVN) of Polymer A polymer was dissolved in m-cresol at a concentration of 0.5 g / dl and measured at 60 ° C. using an Ubbelohde viscometer. (2) Fiber strength (g / denier) and initial elastic modulus (g / denier) The fiber strength was measured by a method according to JIS L1017. (3) Bending hardness (g) of the cord was measured using the device shown in FIG. In FIG. 1, 1
Is a code of the measurement sample, 2 is a support rod for hooking the code,
3 is a wire having a diameter of about 0.8 mm, 4 is a load cell connected to the support rod 2, and 5 is a tension member of a tensile tester.
It is. In FIG. 1, the code 1 having a length of 20 mm is 5
The bending hardness when hooked on the support rods 2 having an interval of mm and bent by hooking the tension member 5 of the tensile tester on the cord 1 was measured and expressed in g.

Example 1 An ethylene / propylene / carbon monoxide polymer (LVN 2.0 dl / g) copolymerized with 7 mol% of propylene was spun at a spinning temperature of 275 ° C., and then stretched 6 times at a plate temperature of 200 ° C. Heat-setting was performed to obtain a tire cord raw yarn of 1500 denier / 750 filament. The tensile strength of the raw yarn was 13.0 g / denier and the initial elastic modulus was 160 g / denier. Subsequently, the raw yarn (stretched yarn) was plied and twisted at a rate of 39T per 10 cm for both initial twisting and upper twisting to obtain a raw cord. Raw code is a computer computer RF manufactured by Ritsura.
L adhesive application and heat setting treatment were performed. The bending hardness of the obtained treated cord was 45 g.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an apparatus used for measuring the bending hardness of a cord.

[Explanation of symbols]

 1: Code of measurement sample 2: Support bar for hooking the code 3: Wire having a diameter of about 0.8 mm 4: Hook connected to the support bar 5: Tension member of tensile tester

Claims (1)

[Claims] 1. A polymer filament comprising a repeating unit represented by the following general formula (1) and having a tensile strength of 10.0 g / denier or more and an initial elastic modulus of 120 g / denier or more. A tire code having a bending hardness of 10 to 80 g. Embedded image