KR20090026052A - Lyocell filament fibers, and tire cords comprising the same - Google Patents

Abstract

The present invention relates to a lyocell filament fiber having a strength retention of 70% or more after a repeated wear test based on 0.5 TPM and a load of 1.0 g / d according to ASTM D 3412 (Yarn to Yarn method), and a tire cord including the same. will be.

The lyocell filament fiber of the present invention has an advantage of less physical degradation caused by friction in the tire cord manufacturing process.

Description

LYOCELL FILAMENT FIBER, AND TIRE CORD COMPRISING THE SAME}

The present invention relates to a lyocell filament fiber having a low physical property deterioration in a tire cord manufacturing process and a tire cord including the same.

The tire is a composite of fiber / steel / rubber and generally has a structure as shown in FIG. 1. In other words, steel and fiber cords serve to reinforce rubber and form a basic skeletal structure in the tire. In other words, compared to the human body is a bone-like role.

The performance required for the cord as a tire reinforcement is fatigue resistance, shear strength, durability, resilience and adhesion to rubber. Therefore, a cord of appropriate material is used according to the performance required for the tire.

Commonly used materials for the cord currently include rayon, nylon, polyester, steel, and aramid, and rayon and polyester are used for body plies (also called carcasses) (6 in FIG. 1), and nylon is mainly a cap. In the ply (4 in FIG. 1), and steel and aramid are mainly used in the tire belt portion (5 in FIG. 1).

The following briefly illustrates the tire structure and its characteristics shown in FIG. 1.

Tread (1): This part is to be in contact with the road surface to provide the necessary frictional force for braking and driving, to have good abrasion resistance, to withstand external shocks, and to generate little heat.

Body Ply (or Carcass) (6): A layer of cord inside the tire, which must support loads, withstand impacts, and be resistant to flexing movements while driving.

Belt (5): Located between the body plies, consisting of steel wires in most cases to mitigate external shocks and maintain a wide tread ground to provide excellent driving stability.

Side Wall (3): refers to the rubber layer between the lower part of the shoulder (2) from the bead (9) and serves to protect the body ply (6) inside.

BEAD (9): A square or hexagonal wire bundle with rubber coating on the wire that rests and secures the tire to the rim.

Inner Liner (7): Located on the inside of the tire instead of the tube, this prevents air leakage and enables pneumatic tires.

CAP PLY (4): A special cord paper placed on the belt of some passenger radial tires that minimizes belt movement when driving.

APEX (8): A triangular rubber filler used to minimize the dispersion of beads, to mitigate external impacts, to protect the beads, and to prevent the ingress of air during molding.

Generally used tire cord material is nylon, polyester, rayon and the like. These materials are limited in size and use, etc. of the tires used due to their advantages and disadvantages.

Nylon fiber has high tensile elongation and high strength, and is mainly used for tires used on curved roads such as heavy trucks and unpaved roads. However, the nylon fiber is not suitable for a tire for a passenger car in which concentrated heat accumulation occurs inside the tire, and a low modulus is used to travel at high speed or require a ride comfort.

Polyester fiber has better shape stability and price competitiveness than nylon, and strength and adhesion are improved due to continuous research, and its usage is increasing in the tire cord field. However, it is not suitable for high-speed running tires because of limitations in heat resistance and adhesive strength.

Rayon fiber, a regenerated cellulose fiber, exhibits excellent strength retention and shape stability at high temperatures. Therefore, rayon fiber is known as an optimal tire cord material. However, due to the strong deterioration due to moisture, thorough moisture management is required during tire manufacturing, and due to the nonuniformity in yarn manufacturing, the rate of defective products is high. Above all, its price / performance ratio is very low compared to other materials, and it is mainly applied only to high speed or expensive tires.

In addition, general cellulose-based tire cords, such as rayon, have a rigid molecular structure and low elongation, and thus, it is difficult to withstand repeated high temperature expansion and contraction in a tire, and technology development for improving them is required.

The present invention is to provide a lyocell filament fiber with less physical degradation in the tire cord manufacturing process.

The present invention is to provide a tire cord comprising the lyocell filament fiber.

The present invention provides a lyocell filament fiber having a strength retention of 70% or more after repeated wear tests based on 0.5 TPM and a load of 1.0 g / d according to ASTM D3412 (Yarn to Yarn method).

The present invention also provides a tire cord comprising the lyocell filament fibers.

Hereinafter, the present invention will be described in more detail.

In the present invention, a filament bundle including a plurality of filament fibers is referred to as a 'multi filament', and a raw cord manufactured by upper and lower edges (or lower and upper edges) of the multifilament is referred to as 'ply twisted yarn', The deep cord treated with the adhesive for the tire cord in the twisted yarn is referred to as 'tire cord' or 'code'.

In addition, in the present invention, "maximum point strength" means the maximum value of the strength measured according to the measuring method according to the American Material Testing Association standard (ASTM) D 885 using Instron's universal material tester, 'elongation' Elongation at the point indicating the maximum point strength means. Hereinafter, unless otherwise specified, strength means maximum point strength, and elongation means maximum point elongation.

The present inventors have conducted studies to improve the morphological stability and fatigue resistance of lyocell tire cords used as reinforcing materials for tires, and have found that wear resistance can be improved by minimizing fibrillation of lyocell filament fibers. The present invention has been completed.

The lyocell filament fiber to be developed in the present invention is characterized in that the strength retention is 70% or more after repeated abrasion test based on 0.5 TPM, 1.0 g / d load according to ASTM D3412 (Yarn to Yarn method), and The strength retention rate is 70 to 90%. The strength retention is defined by the following formula (1).

[Calculation 1]

Strength retention rate (%) = St _a / St _i × 100

In the above formula, St _i is the strength (g / d) before the wear test, St _a is the strength (g / d) after the wear test.

The strength value before and after the wear resistance test may be based on the measured value for the multifilament having a total number of filaments of 1000 and a total fineness of 1650d. However, the numerical value is only a reference for the measurement, the lyocell filament fiber of the present invention is not necessarily limited to having the filament number, fineness, twist number, even if the number and total fineness of the filament fiber is changed The contrast does not change.

Typically, the manufacturing process of the tire cord is a spinning process for producing filament fibers, a twisting process for producing a twisted yarn by twisting the spun multifilament fibers, and give the adhesive for the tire cord to the twisted twisted yarn The dipping process can be broadly classified.

In the spinning process, the twisting process, and the dipping process, the filament fibers are subjected to frictional force from the surface of various rollers, and may be exposed to high temperature, high humidity, or high tension state depending on the requirements of each process.

In particular, lyocell filament fibers, which are cellulose filament fibers, have a rigid molecular structure and have low elongation compared to thermoplastic resins, and thus, wear resistance against friction generated during processes such as weaving and weaving is very important.

In the present invention, the strength retention is a measure of durability against wear, and the strength retention must be 70% or more to exhibit excellent physical properties even when the tire cord is manufactured.

In addition, the filament fiber of the present invention may have an elongation retention of 70 to 100% after the abrasion test. The elongation retention is defined by the following Equation 2.

[Calculation 2]

Elongation Retention Rate (%) = Sr _a / Sr _i × 100

Where Sr _i is the elongation (%) before the abrasion test and Sr _a is the elongation (%) after the abrasion test.

The filament fibers of the present invention should have excellent strength and elongation values as such, and may have a strength of 6 to 8 g / d and an elongation of 7 to 15% before abrasion testing of the filament fibers.

In general, the tire temperature increases due to friction during driving of the vehicle, and particularly, during high speed driving, the tire cord is exposed to the harsh conditions of high temperature and high pressure as the high temperature and high pressure state are maintained for a long time. At this time, when the strength retention rate of the filament fibers constituting the tire cord is low, the shape of the cord may be deformed, which may reduce the running performance or the tire cord may be broken by external stress.

In addition, the lyocell filament fiber of the present invention may be a wear test number of times from the wear resistance test to the cutting to more than 1000 times, may be 1500 to 2000 times. The higher the number of wear tests, the better the wear resistance. In the test, 'cutting' refers to a state in which 100% of the multifilament used in the test is cut.

The tire cord of the present invention comprises the lyocell filament fibers. The tire cord may comprise a composite yarn of 2-3 plies having a total number of filaments of 400 to 6000, a total fineness of 400 to 9000 deniers, and a twist number of 200 to 600 TPM.

The lyocell tire cord of the present invention is excellent in shape stability and durability and can be applied to applications such as body plies or cap plies of pneumatic tires. In addition, the tire to which the tire cord of the present invention is applied has little shape deformation and can exhibit stable high-speed driving performance.

The lyocell filament fiber of the present invention comprises the steps of dissolving cellulose in a mixed solvent of N-methylmorpholine-N-oxide (NMMO) and water to prepare a spinning dope; Spinning a cellulose filament from the spinning dope using a spinning device equipped with a spinning nozzle; And solidifying, washing, and drying the spun cellulosic filaments.

In this case, as the spinning stock solution, 7 to 18 wt% of cellulose is dissolved in a mixed solvent including N-methylmorpholine-N-oxide (NMMO): water in a weight ratio of 93: 7 to 85:15. The spinning solution may be swelled in a mixed solvent including N-methylmorpholine-N-oxide (NMMO): water in a weight ratio of 90:10 to 50:50, and then N-methylmorpholine-N- It can be prepared according to the process of removing water such that the weight ratio of oxide (NMMO): water is 93: 7 to 85:15 and the final content of cellulose is 5 to 35% by weight, more preferably 7 to 18% by weight.

In addition, the drying temperature in the drying step of the filament may be adjusted to 90 to 200 ℃, or 100 to 150 ℃. The drying step may be carried out in a one-step drying process, it may also be carried out in a multi-stage drying process to vary the drying process conditions by dividing the interval. In the multistage drying step, specific drying conditions may be arbitrarily selected as necessary within the above temperature range.

In addition, the step of imparting a spinning emulsion to the filament before the drying step, during the drying step, by adjusting the moisture content of the filament to 50 to 100% by weight before the spinning emulsion is applied to control the uniform adhesion properties and permeability of the emulsion To achieve the best wear resistance. That is, the moisture content of the filament may be 50% by weight or more in order to prevent the emulsion from penetrating too deeply into the filament, and the moisture content of the filament is 100% by weight in order to improve the adhesion property of the oil to the filament. It may be

In addition, the tire cord of the present invention is prepared by forming the lyocell multifilament in the form of a twisted yarn of 2 to 3 ply, by treating the twisted yarn with an adhesive solution for a tire cord according to a conventional dipping method, and drying and heat treatment Can be prepared.

In addition, as the adhesive solution, a conventional adhesive solution for tire cords may be used, and preferably, a resorcinol-formaldehyde-latex (RFL) adhesive solution may be used.

The cord passing through the adhesive solution is manufactured as a tire cord through a drying process and a heat treatment process. The drying process is performed at a tension of 20 to 2000 g / cord for 1 minute to 10 minutes at 105 to 160 ° C, and the heat treatment process is 20 to 2000 g / cord for 1 minute to 10 minutes at 105 to 220 ° C. It can be carried out under tension.

In the drying step, moisture existing in the lyocell is dried, and in the heat treatment step, the impregnation solution is reacted to impart adhesion to the tire cord.

In the present invention, matters other than those described above can be added or subtracted as necessary, and therefore the present invention is not particularly limited.

The lyocell filament fiber of the present invention has an excellent wear resistance and has a low physical property deterioration caused by friction in a tire cord manufacturing process, and the tire cord including the filament fiber has an excellent shape stability and durability.

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Example 1

A cellulose sheet (buckeye V-81) was put into a grinder equipped with a 100 mesh filter to prepare a cellulose powder having a diameter of 1700 μm or less.

The cellulose powder was swollen in 50 wt% NMMO aqueous solution. At this time, the content of cellulose in the NMMO solution was 6.5% by weight.

The swelled cellulose slurry was maintained at an internal temperature of 90 ° C. and injected into a kneader maintained at an absolute pressure of 50 mmHg at a rate of 16 kg / hour using a rotary valve pump, while 50% by weight of NMMO aqueous solution was 89% by weight of NMMO aqueous solution. After completely dissolving the cellulose while removing the excess moisture to be discharged through the spinning screw through the discharge screw. At this time, the cellulose concentration of the discharged spinning dope was 11% by weight, it was confirmed that the homogeneous state does not contain undissolved cellulose particles.

The cellulose dope was adjusted so that the final filament total fineness was 1,650 denier, and was spun using a nozzle having 1000 nozzles and a nozzle cross-sectional area of 0.047 mm 2.

The discharged and solidified multifilament yarn was completely removed by the sprayed flushing liquid, and the undried multifilament yarn was dried on a drying roll consisting of three stages to obtain a lyocell multifilament. At this time, the tension between the first and second stages of the drying roll was adjusted to 0.2 g / d, and the tension between the second and third stages was adjusted to 0.3 g / d, and the temperature of each drying roll was 120, 120, and 105 degrees. Adjusted to.

At this time, a step of applying a diester compound spinning emulsion to the filament fibers between the first and second stages of the drying rolls, the emulsion is given in the state that the water content of the filament fibers passed through the first stage of the drying rolls is 50% by weight Adjusted to.

Example 2

As described in Table 1 below, except that the cellulose concentration of the discharged spinning dope, the tension between the first and second stages of the drying rolls, the tension between the second and third stages, and the temperature conditions of each drying roll were changed. The lyocell filament fibers were prepared in the same manner as in Example 1. That is, the cellulose concentration of the discharged spinning dope is 10.5% by weight, the tension between the first and second stage of the drying roll is 0.18 g / d, the tension between the second and the third stage is 0.25 g / d, and each drying roll in sequence The temperature of was adjusted so that it might be 120 degreeC, 120 degreeC, and 100 degreeC.

Example 3

As described in Table 1 below, except that the cellulose concentration of the discharged spinning dope, the tension between the first and second stages of the drying rolls, the tension between the second and third stages, and the temperature conditions of each drying roll were changed. The lyocell filament fibers were manufactured in the same manner as in Example 1. That is, the cellulose concentration of the discharged spinning dope is 11.5% by weight, the tension between the first and second stage of the drying roll is 0.22 g / d, the tension between the second and the third stage is 0.34 g / d, each drying roll in sequence The temperature of was adjusted to be 125 ° C, 125 ° C, and 105 ° C.

Comparative Example 1

Kodinka 700 Super 3 filament bundle (1000 filament number, total fineness 1650 denier) was used.

Experimental Example 1

[Measurement of Elongation of Filament Before Wear Test]

The filament fibers according to Examples 1 to 3 and Comparative Example 1 were twisted at 80 TPM, respectively, to prepare test samples, and dried in an oven at 105 ° C. for 4 hours. Then, the strength of the filament (St _i ) and elongation (Sr _i ) was measured according to the ASTM D-885 method using an Instron universal material tester for the sample, the results are summarized in Table 1 below.

[Measurement of Elongation of Filament after Wear Test]

The filament fibers according to Examples 1 to 3 and Comparative Example 1 were each twisted at 80 TPM to prepare a test sample, and were dried in an oven at 105 ° C. for 4 hours. Thereafter, the sample was subjected to abrasion test 1500 times at 0.5 TPM and 1.0 g / d load according to ASTM D1577 according to ASTM D3412 (Yarn to Yarn method), and then, using an universal material tester manufactured by Instron, Inc. According to the method, the strength (St _a ) and elongation (Sr _a ) of the filament were measured, and the results are summarized in Table 1 below.

[Measurement of the number of wear test until cutting]

The filament fibers according to Examples 1 to 3 and Comparative Example 1 were each twisted at 80 TPM to prepare a test sample, and dried for 4 hours in an oven at 105 ° C. Thereafter, the sample was subjected to abrasion testing until trimming based on a load of 1.0 g / d according to ASTM T1512 and ASTM D1577 according to ASTM D3412 (Yarn to Yarn method), and the number of abrasion tests until cutting was shown in Table 1 below. In summary.

TABLE 1

Example 1 Example 2 Example 3 Comparative Example 1 Cellulose Concentration (wt%) 11.0 10.5 11.5 Kodenka 700 Super 3 1st stage / 2nd stage tension (g / d) 0.2 0.18 0.22 2 stage / 3 stage tension (g / d) 0.3 0.25 0.34 1-stage drying roll temperature (℃) 120 120 125 2-stage drying roll temperature (℃) 120 120 125 3-stage drying roll temperature (℃) 105 100 105 St _i (g / d) 7.2 7.0 7.7 5.4 St _a (g / d) (@ 1500) 6.4 6.0 6.9 Cut off Strength retention rate (%) 88.2 85.8 89.6 0.0 Sr _i (%) 8.7 8.4 8.3 12.8 Sr _a (%) (@ 1500) 6.9 6.9 7.6 Cut off Elongation Retention Rate (%) 78.9 82.5 91.2 0.0 Number of cuts (times) 1265 1433 1647 912

As shown in Table 1, the filament fibers according to Examples 1 to 3 of the present invention has excellent strength retention of 88.2-89.6%, elongation retention ratio of 78.9-91.2%, and the number of times of abrasion test until cutting. It can be seen that the durability against wear is excellent. However, the normal filament fibers of Comparative Example 1 had very poor strength retention and elongation retention ratio, and the durability against abrasion was also inferior to Examples 1-3.

Examples 4-6 and Comparative Example 2

The filament bundles according to Examples 1 to 3 and Comparative Example 1 were each subjected to 350 TPM using a Cable & Cord 3 type twister (C.C Twister, Allma Co.) to prepare yarns for tire cords.

2 ply of the yarn for the cord was twisted, respectively, to prepare tire cord dough, and the twisted yarn was twisted with a twist number of 350 TPM.

The prepared cord dough was 2.0% by weight of resorcinol, 3.2% by weight of formalin (37%), 1.1% by weight of sodium hydroxide (10%), styrene / butadiene / vinylpyridine (15/70/15) rubber (41%) (Styrene / butadiene / vinylpyridine latex containing 41% rubber) was immersed and passed through a RFL adhesive solution containing 43.9% by weight and the balance of water, and then dried at 150 ° C for 2 minutes under a tension of 300 g / cord. , Tire cord was prepared by heat treatment at 180 ° C. for 2 minutes under a tension of 500 g / cord.

[Fatigue resistance measurement]

After repeated elongation / compression of 4% elongation and 4% compression rate at 2,500 rpm for 10 hours at 80 ° C., the physical properties of the tire cords were evaluated according to the following equation 1. The results are shown in Table 2.

[Calculation 1]

Fatigue resistance = (strong fatigue resistance / strong fatigue resistance) × 100

TABLE 2

Code strong (kgf) Code elongation (%) Medium Elongation (%) @ 4.5kgf Fatigue resistance (%) Example 4 17.4 7.2 1.7 93.8 Example 5 17.3 7.7 1.8 94.2 Example 6 17.8 7.2 1.8 92.1 Comparative Example 2 15.4 11.3 2.2 84.5

Through the results in Table 2, when using the lyocell filament fibers of the present invention, it can be seen that the physical properties of the cord are all improved.

The lyocell filament fibers of the present invention can be used in the production of tire cords having excellent wear resistance and exhibiting high speed driving performance.

1 is a partial cutaway perspective view showing a configuration of a general tire.

Claims (7)

A lyocell filament fiber having a strength retention of 70% or more after a repeated wear test based on 0.5 TPM and a load of 1.0 g / d according to ASTM D3412 (Yarn to Yarn method). The method of claim 1, The lyocell filament fiber having the strength retention of 70 to 90%. The method of claim 1, The lyocell filament fiber is a lyocell filament fiber having an elongation retention of 70 to 100% after the abrasion test. The method of claim 1, The lyocell filament fiber is a lyocell filament fiber having a strength of 6 to 8 g / d, elongation 7 to 15% before the wear test. The method of claim 1, The lyocell filament fiber is a lyocell filament fiber that is at least 1000 times the wear test until cutting. The method of claim 1, The lyocell filament fiber is a lyocell filament fiber is 1000 to 2000 times the number of wear test until cutting. Tire cord comprising the lyocell filament fiber according to claim 1.

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