KR101273701B1 - Aramid Fiber Cord and Method for Manufacturing The Same - Google Patents

Abstract

The present invention relates to an aramid fiber cord having excellent tenacity and formability, and a method of manufacturing the same. The aramid fiber cord of the present invention includes aramid-bonded yarn, wherein the aramid twisted yarn is And aramid single yarns having a twist of the first soft water, wherein the aramid single yarns are twisted together in a second soft water, wherein the first soft water is less than the second soft water.

Aramid, Fiber Cord

Description

Technical Field [0001] The present invention relates to an aramid fiber cord,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to aramid fiber cords and a method for manufacturing the same, and more particularly, to aramid fiber cords and a method for producing the same having excellent tenacity and formability.

Background Art [0002] As a reinforcing material for rubber products such as tires, conveyor belts, V-belts, hoses and the like, fiber cords, in particular, fiber cords treated with adhesives are widely used. The material of the fiber cord includes nylon fiber, polyester fiber, and rayon fiber. One of the important ways to improve the performance of finished rubber products is to improve the properties of the fiber cords used as reinforcements.

Nylon fibers, which generally have excellent elongation and strength, are used in heavy trucks that are subjected to heavy loads and in tires of vehicles that travel on bumpy roads such as unpaved roads. However, since nylon fibers have a low modulus, they are not suitable for racing vehicles traveling at high speeds and for tires of passenger cars requiring a good ride feeling.

Polyester fiber is superior in shape stability and price competitiveness compared to nylon fiber, and its usage in tire cord field is increasing, but it is not suitable for tire of high-speed driving vehicle due to low heat resistance and adhesion to rubber.

Rayon fibers, which are regenerated cellulose fibers, exhibit excellent strength retention and shape stability at high temperatures. However, since rayon fiber is strongly deteriorated by moisture, thorough moisture management is required when manufacturing tires, and above all, there is a problem in that the strength is very low compared to other materials.

On the other hand, in many applications, such as heavy duty vehicles, racing vehicles, aircraft, agricultural vehicles, tire cord reinforcing cords are required to have much higher strength and modulus than can be obtained with polyester or nylon fibers. The fiber capable of providing such high strength and modulus is an aromatic polyamide fiber called so-called aramid.

However, because aramid fibers have inherent high modulus properties, the fiber cords produced using them have very low formability. Thus, when the fiber cord having a low formability is used as a tire reinforcement material, there is a problem that the molding of the tire is difficult.

Accordingly, the present invention relates to an aramid fiber cord and a method of manufacturing the same, which can prevent problems due to limitations and disadvantages of the related art.

An advantage of the present invention is to provide an aramid fiber cord and a method of manufacturing the same, which satisfy the strength properties required in the reinforcement of a rubber product and at the same time have excellent moldability.

Further features and advantages of the invention will be described hereinafter, and will in part be obvious from the description. Alternatively, other features and advantages of the invention may be learned through practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The objects and other advantages of the present invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

In order to achieve the above advantages, and in accordance with the purpose of the present invention, aramid conjugated yarn (cabled yarn), wherein the aramid conjugated yarn comprises aramid single yarns each having a twist of the first soft water, The aramid single yarn is twisted together in a second soft water, wherein the first soft water is less than the second soft water is provided.

In another aspect of the present invention, the step of preparing the aramid single yarn by rolling the aramid multifilament in the first soft water; And arranging the aramid single yarn 2 plies together with a second soft water to produce aramid twisted yarn, wherein the first soft water is less than the second soft water. Is provided.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

The aramid fiber cord according to the present invention has excellent moldability with low initial modulus value while satisfying strength characteristics generally required for tire cords such as heavy equipment vehicles, racing vehicles, aircrafts, agricultural vehicles, and the like. Therefore, the aramid fiber cord of the present invention has an effect of facilitating the molding of the tire as well as performing an excellent reinforcement function when used as a tire reinforcement material.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

As used herein, the term 'multifilament' refers to a bundle of filaments formed by solidifying the spinning dope spun through the spinneret.

As used herein, 'single yarn' refers to a single strand of yarn made by twisting a multifilament in either direction.

As used herein, the term "cabled yarn" means a yarn formed by twisting two or more single yarns together in one direction, and may be referred to as a "raw cord".

The twisting of the yarn in the counterclockwise direction is called Z-twist, and the twisting of the yarn in the clockwise direction is called S-twist.

As used herein, 'twist number' means the number of twists per meter, and the unit is a twist per meter (TPM).

As used herein, 'fiber cord' refers to a twisted yarn containing an adhesive to be directly embedded in a rubber product, and may also be referred to as a 'dipped cord'. If the fabric is made by weaving twisted yarns and then immersed in the adhesive solution, the fabric containing the adhesive is also included in the 'fiber cord'.

Hereinafter, an embodiment of a method for producing an aramid fiber cord of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a system for producing aramid fibers according to an embodiment of the present invention.

First, spinning dope prepared by dissolving an aromatic polyamide polymer having an inherent viscosity (IV) of 5.0 to 7.0, for example, poly (paraphenylene terephthalamide: PPD-T) in a concentrated sulfuric acid solvent. After spinning using a spinneret (100) using a spinneret (100) to form a multifilament (coagulation bath) by coagulation in the coagulation bath (200) through an air gap (air gap).

When the radiation passing through the spinneret 100 passes through the coagulating solution, the sulfuric acid in the radiation is removed and multifilaments are formed. When the sulfuric acid is rapidly removed from the surface of the radiation, The surface is first solidified and the uniformity of the multifilament is lowered. Therefore, it is preferable to add sulfuric acid to the coagulating solution in order to prevent sulfuric acid from leaking out rapidly from the surface of the radiation.

Subsequently, the sulfuric acid remaining in the obtained multifilament is removed. The sulfuric acid used in the preparation of the radial dope may be largely removed while the radiation passes through the coagulation bath 200, but may remain without being completely removed. Also, when sulfuric acid is added to the coagulating solution of the coagulation bath 200 to uniformly remove sulfuric acid from the radiation, the possibility of sulfuric acid remaining in the resulting multifilament is high. It is very important to completely remove the sulfuric acid remaining in the multifilament since any amount of sulfuric acid remaining in the multifilament may adversely affect the aramid fiber properties. The sulfuric acid remaining in the multifilament can be removed through a washing process using water or a mixed solution of water and an alkali solution.

The washing process may be performed in a multi-step process, for example, first washing with multi-filament containing sulfuric acid in a first washing tank 300 containing 0.3 to 1.3% of an aqueous caustic solution, and then The second washing in the second washing tank 400 containing 0.01 to 0.1% of the thinner caustic water solution. First and second water wash rolls 310 and 410 are installed in the first and second water storage tanks 300 and 400 to move the multifilaments.

Then, a drying process for removing moisture remaining in the multifilament is performed in the drying section 500. [ The drying process may control the moisture content of the filament by adjusting the time the filament touches the drying roll 510 in the drying unit 500 or by adjusting the temperature of the drying roll 510.

The dried multifilament is heat treated in the heat treatment part 600 including a plurality of heat treatment rolls 610.

Subsequently, aramid single yarn is manufactured by pinching aramid multifilament using a twisting machine. The aramid sintered yarn is then prepared by twisting together the two strands of aramid yarns. According to one embodiment of the present invention, the aramid single yarn is prepared by giving twist in Z-direction to the multifilament, and the aramid twisted yarn is twisted together with two strands of aramid single yarn Is manufactured.

On the other hand, although the number of single yarn and twisted yarn is one of the important factors that determine the physical properties of the aramid fiber cord, the study on how much each of them affects what properties. For this reason, in the conventional aramid fiber cords, the number of single yarns and the number of twisted yarns is the same, and this embodiment has been generally accepted in the art without any objection.

However, the inventor of the present invention steadily studied how much the number of the single yarn and the twisted yarn's training affected on the physical properties of the aramid fiber cord, and as a result, the single yarn's training was not related to the strength of the aramid fiber cord compared to the years of the twisted yarn. While more influenced, it was found that the number of years of combined yarn has a greater effect on the initial modulus of the aramid fiber cord, e.g., Load At Specific Elongation (LASE), than that of single yarn. .

Therefore, unlike conventional aramid fiber cords in which the number of single yarns and the number of twisted yarns are the same, the aramid cord of the present invention is characterized in that the number of single yarns is smaller than the number of years of the twisted yarn. This ensures excellent strength by making the number of single yarns, an important factor for determining the strength of the aramid fiber cord, less than that of the twisted yarns. This is because LASE and excellent moldability due to low 0.5% elongation can be obtained by making more than the number of soft yarns.

For example, aramid fiber cords having 200 TPM of single yarn and 300 TPM of twisted and twisted yarns have better molding despite having almost the same strength as aramid fiber cords having both 200 and 1PM TPM. It has a high strength, although the moldability is almost the same as that of the aramid fiber cord having 300 TPM of both single yarn and twisted yarn.

According to one embodiment of the present invention, the training years of the twisted yarn is 200 to 600 TPM and the soft yarn is less than the training of the twisted yarn. When the number of years of combined twisted yarn is less than 200 TPM, there is a disadvantage that the elongation is low and the modulus is high and the moldability is low. On the contrary, when the number of years of twisted twisted yarn exceeds 600 TPM, the strength of the twisted twisted yarn is excessively low.

It is preferable that the number of years of single yarn is 60 to 90% of the number of years of combined yarn. For example, assuming that the number of years of twisted yarn is fixed at a certain number of times from 200 to 600 TPM, the modulus of the twisted yarn is excessive compared to the strength gain obtained when the number of single yarns is less than 60% of the number of years of the fixed twisted yarn. Highly deteriorated molding characteristics, when applied to the tire can reduce the durability of the tire. On the contrary, when the number of trains of single yarn exceeds 90% of the number of years of twisted yarn, it is inefficient because of the strong loss of the twisted yarn of the twisted yarn compared with the molding property gain obtained.

The aramid twisted yarn prepared as above is immersed in a resorcinol-formaldehyde-latex (RFL) solution. In this case, 1-bath dipping or 2-bath dipping can be used. According to one embodiment of the invention, the RFL adhesive solution comprises 2.0% by weight of resorcinol, 3.2% by weight of formalin (37%), 1.1% by weight of sodium hydroxide (10%), 43.9% by weight of styrene / butadiene / Vinylpyridine (15/70/15) rubber (41%), and water.

According to one embodiment of the present invention, the aramid twisted yarn is immersed in a resorcinol-formaldehyde-latex (RFL) solution such that the pickup ratio of the adhesive resin is 3 to 12% by weight based on the arimid twisted yarn. When the pickup rate is less than 3% by weight, the adhesion of the aramid fiber cord with the rubber is lowered. When the pickup rate is more than 12% by weight, the penetration rate of the RFL solution into the fiber cord is too high. Decreases the strength and fatigue resistance.

On the other hand, in order to produce aramid fiber cord in the form of a fabric, the fabric is woven with aramid twisted yarn and the fabric is immersed in RFL solution.

The aramid fiber cord is completed by drying the aramid twisted yarn or fabric which has been subjected to the RFL solution by dipping for 10 to 400 seconds at 105 to 200 ° C and then heat-treated at 105 to 300 ° C for 10 to 400 seconds. The drying process is for removing moisture present in the aramid twisted yarn, and the heat treatment step is for imparting adhesion to the aramid fiber cord with rubber by reacting the RFL solution contained in the aramid twisted yarn.

On the other hand, when each of the drying and heat treatment time is shorter than the above range, or when each of the drying and heat treatment temperatures is lower than the above range, the adhesive force of the aramid fiber cord with the rubber is lowered. On the contrary, when the drying and heat treatment times are longer than the above range or the drying and heat treatment temperatures are higher than the upper range, the adhesion of the aramid fiber cord to rubber is lowered due to excessive heat, and the physical properties such as strength and fatigue resistance are lowered .

Hereinafter, the present invention will be described in detail through examples and comparative examples. It should be noted, however, that the following examples are intended to assist the understanding of the present invention and should not limit the scope of the present invention.

Example 1

Spinning dope was prepared by dissolving poly (paraphenylene terephthalamide: PPD-T) having an intrinsic viscosity (I.V.) of 5.5 in 100% concentrated sulfuric acid solvent. The radial dope was radiated through a spinneret and then solidified in a coagulation bath containing 13% aqueous sulfuric acid through an air gap of 7 mm to produce an aramid multifilament.

In order to remove residual sulfuric acid from the multifilament, the multifilament was first washed in a first water bath containing 0.5% aqueous caustic solution and then in a second water bath containing 0.05% more diluted caustic solution. A second wash was performed.

Subsequently, a drying process was performed to remove moisture remaining in the multifilament. The dried multifilament was heat treated in a heat treatment part including a plurality of heat treatment rolls.

Aramid single yarn was prepared by Z-twisting the heat treated aramid multifilament with 285 TPM using Alma Co.'s Ring type twister, and then performing two strands of aramid single yarn together at 300 TPM. S-twist) to produce aramid twisted yarn. That is, the training ratio of single yarns to the training of the twisted yarns was about 95%.

Thus prepared aramid plywood yarn was 2.0% by weight of resorcinol, 3.2% by weight of formalin (37%), 1.1% by weight of sodium hydroxide (10%), 43.9% by weight of styrene / butadiene / vinylpyridine (15/70). / 15) It was immersed in a solution of resorcinol-formaldehyde-latex (RFL) containing rubber (41%), and water. The pick-up rate of the adhesive resin was controlled to be about 10% by weight based on the arimid-ply twisted yarn.

The aramid fiber cord, which was made to contain the RFL solution by immersion, was dried at about 150 ° C. for 100 seconds and then heat treated at 200 ° C. for 100 seconds to complete the aramid fiber cord.

Examples 2 to 8

Aramid fiber cords were prepared in the same manner as in Example 1 except that the lower station number of aramid single yarn and the upper station number of aramid conjugated yarn were determined as shown in Table 1 below.

[Table 1]

Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Aramid single yarn
Training (TPM) 270 240 200 180 150 160 480 Aramid Synthesis
Training (TPM) 300 300 300 300 300 200 600 % Training of single yarn to training
90
80
67
60
50
80
80

Comparative Examples 1 to 4

Aramid fiber cords were prepared in the same manner as in Example 1 except that the lower station number of aramid single yarn and the upper station number of aramid twisted yarn were determined as shown in Table 2 below.

[Table 2]

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Training of Aramid Single Yarn (TPM) 200 300 120 520 Aramid Combined Training (TPM) 200 300 150 650 % Training of single yarn to training 100 100 80 80

Tenacity and LASE at 0.5% elongation of the aramid fiber cords obtained by the above examples and comparative examples were obtained by the following methods, respectively.

Strength of aramid fiber cord

Strength at break of aramid fiber cord by applying 300 m / min tensile speed to 250 mm sample field using Instron Engineering Corp., Canton, Mass according to ASTM D-885 test method Break) was measured and the strength (g / d) was obtained by dividing the measured breaking strength by the fineness of the aramid fiber cord.

LASE at 0.5% elongation of aramid fiber cord

According to the ASTM D-885 test method, a Stress-Strain Curve was obtained using an Instron Engineering Corp. (Canton, Mass). Using this stress-strain curve, LASE (Kgf) was obtained at 0.5% elongation of the aramid fiber cord by obtaining a load when the length strain was 0.5%.

The strength and 0.5% elongation of the aramid fiber cord of Examples and Comparative Examples obtained by the above method are shown in Table 3 below.

[Table 3]

practice
Example 1 practice
Example 2 practice
Example 3 practice
Example 4 practice
Example 5 practice
Example 6 practice
Example 7 practice
Example 8 compare
Example 1 compare
Example 2 compare
Example 3 compare
Example 4 burglar
(g / d) 17.5 18.3 18.5 18.9 19.0 19.2 20.2 15.5 18.9 17.3 21.9 14.5 0.5% elongation
LASE
(Kgf) 4.1 4.0 4.0 4.2 4.4 4.5 6.9 2.5 7.1 4.0 7.4 2.3

As can be seen from Table 3 above, the strength of the aramid fiber cord is particularly related to the number of aramid single yarn, LASE at 0.5% elongation of the aramid fiber cord was found to be particularly related to the number of years of aramid twisted yarn.

That is, the aramid fiber cords of Examples 1 to 8 in which the number of soft yarns of the twisted yarns are constant at 300 TPM and the number of single yarns is less than 300 TPM, are the same as those of the aramid cord of Comparative Example 2, in which the number of single yarns and the number of years of the twisted yarns are 300 TPM. It can be seen that the comparison has higher strength despite showing LASE (almost the same formability) at nearly the same 0.5% elongation.

On the other hand, the aramid fiber cord of Example 4 in which the number of years of single yarn is 200 TPM and the number of years of twisted yarn is 300 TPM is almost the same as compared with the aramid cord of Comparative Example 1, in which both the number of soft yarns and the number of years of twisted yarn are 200 TPM. It can be seen that LASE (better moldability) at 0.5% elongation despite

On the other hand, as in the case of Comparative Example 3, even if the number of years of single yarn is 80% of the number of years of twisted yarn, when the number of years of twisted yarn is less than 200 TPM, the LASE value at 0.5% elongation is high to ensure the desired formability none. On the contrary, as in the case of Comparative Example 4, even if the number of years of single yarn corresponds to 80% of the years of the twisted yarn, when the number of years of combined twisted yarn exceeds 600 TPM, desired strength characteristics cannot be secured.

As a result, the aramid fiber cord of the present invention has a soft water of 200 to 600 TPM and the soft yarn of the single twisted yarn less than the soft water of the twisted yarn can maintain high strength when used as a reinforcing material of a tire, as well as perform excellent reinforcement function. Having a low initial modulus has the effect of facilitating the molding of the tire at the same time.

Meanwhile, in Examples 1 and 6 in which the ratio of the number of years of single yarn to the number of years of twisted yarn is out of the range of 60 to 90%, any one of the characteristics of LASE at strength and 0.5% elongation relative to the other embodiments was compared. It is found that the ratio of the number of years of single yarn to the number of years of twisted yarns is particularly preferably in the range of 60 to 90%.

The accompanying drawings are included to assist in understanding the present invention and to form a part of the specification, to illustrate embodiments of the present invention, and to explain the principles of the present invention together with the detailed description of the invention.

1 is a view schematically showing a system for producing aramid fibers according to an embodiment of the present invention.

<Explanation of Signs of Major Parts of Drawings>

100: spinneret # 200: coagulation tank

300: first water washing tank # 310: first water washing roll

400: 2nd water washing tank 410: 2nd water washing roll

500: drying unit 510: drying roll

600: heat treatment unit 610: heat treatment roll

 700: winder

Claims (7)

Including aramid cabled yarn, The aramid conjugated yarn includes single aramid yarns each having a twist of a first soft water, The aramid single yarns are twisted together in a second soft water, The first soft water is less than the second soft water aramid fiber cord. The method of claim 1, Each of the aramid single yarns is a Z-twisted aramid multifilament, And the aramid single yarns (S-twisted) together to form the aramid conjugated yarn. The method of claim 1, The second soft water is 200 to 600 TPM, The first soft water is an aramid fiber cord, characterized in that 60 to 90% of the second soft water. The method of claim 1, The aramid fiber cord has a strength (Tenacity) of 15 ~ 21g / d and a LASE (LASE at 0.5%) value at 0.5% elongation of 2.5 ~ 7.0 Kgf. Preparing aramid single yarn by rolling the aramid multifilament with first soft water; And Comprising the two aramid single yarn (plies) in a second station together to prepare aramid twisted yarn, The first soft water is less than the second soft water manufacturing method of the aramid fiber cord. 6. The method of claim 5, The second soft water is 200 to 600 TPM, The first soft water is 60 to 90% of the second soft water manufacturing method of the aramid fiber cord. 6. The method of claim 5, Immersing the aramid twisted yarn in an adhesive solution; Drying the aramid twisted yarn containing the adhesive; And The method of claim 1, further comprising the step of heat-treating the dried aramid twisted yarn.

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