KR101432865B1

KR101432865B1 - Method for manufacturing Aramid staple fiber

Info

Publication number: KR101432865B1
Application number: KR1020100136241A
Authority: KR
Inventors: 한인식
Original assignee: 코오롱인더스트리 주식회사
Priority date: 2010-12-28
Filing date: 2010-12-28
Publication date: 2014-08-26
Also published as: KR20120074418A

Abstract

INDUSTRIAL APPLICABILITY The present invention provides an aramid filament which is excellent in winding ability by using an aramid filament containing a sufficient amount of water and having a low crystallinity in place of a conventional manufacturing method in which an aramid filament produced through a spinning process is wound around a core tube and then unwound and cut again, The present invention relates to a method for producing an aramid staple fiber capable of improving productivity as an aramid filament manufacturing process and a staple manufacturing process are continuously performed. The method for producing an aramid staple fiber of the present invention comprises the steps of: producing an aramid filament having an elastic modulus of 300 g / d or more; Continuously joining the aramid filaments without winding the aramid filaments to produce a tow; Heat treating the tow; Subjecting the heat treated tow to crimping; And cutting the crimped tow.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing an aramid staple fiber,

The present invention relates to a method for producing aramid staple fiber, and more particularly, to a method for producing aramid staple fiber having high strength and excellent glue property.

In general, aromatic polyamide fibers, commonly referred to as aramid fibers, include para-aramid fibers having a structure in which benzene rings are linearly connected through an amide group (CONH) and non-aramid fibers. Para-aramid fibers have excellent properties such as high strength, high elasticity and low shrinkage, and they have a strength of about 5 mm and a thickness of about 2 mm.

These aramid fibers have excellent heat resistance, flame retardancy, chemical resistance and strength and have been widely used in fire fighting apparel, protective apparel, safety gloves, etc. However, since they have a strong molecular structure and high crystallinity, they are dyed smoothly It is difficult to obtain various colors, the elasticity is poor, the elasticity is poor, and there is a problem that the elasticity is limited by the elasticity.

To solve this problem, there has been proposed a technique for an aramid staple produced by combining aramid filaments made together, crimping a crimped tow, cutting the filament into a certain length, and so on.

However, the conventional method of producing aramid staple fiber has the following problems.

First, since the aramid filament produced through the spinning process is once wound around the core tube and then unwound and cut, the process is complicated and the process time is long.

Second, the aramid filaments should be given a radial emulsion before the aramid filaments produced by the spinning process are wound around the core tube. Since such radial emulsions are intended to solve the problems that occur when winding the core filaments, Thereafter, it is troublesome to remove the radiated emulsion. In other words, because aramid staple fibers are used for spinning yarn production, aramid staple fibers must be treated with spinning emulsion in order to improve the operation of the spinning process. Spray emulsions and spinning emulsions have different roles as described above, And thus there is a need to remove the spinning emulsion before applying the spinning emulsion to the aramid filament.

Third, there is a problem that the aramid filaments are loosened from the core tube and tension is applied to the aramid filaments during the process of making the tow, so that the process of making the tow is not easy.

Fourth, there is a problem in that the crimpability of the staple deteriorates due to the use of the aramid filament having a low flexural modulus.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a method for producing aramid filaments, which comprises the steps of winding an aramid filament produced through a spinning process on a paper tube, The present invention provides a method for producing an aramid staple fiber which is excellent in winding property by using the falling aramid filament and can be improved in productivity as an aramid filament manufacturing process and a staple manufacturing process are continuously performed.

In order to achieve the above objects, the present invention provides a process for producing an aramid filament having an elastic modulus of 300 g / d or more; Continuously joining the aramid filaments without winding the aramid filaments to produce a tow; Heat treating the tow; Subjecting the heat treated tow to crimping; And cutting the crimped tow. The present invention also provides a method for producing an aramid staple fiber.

The present invention has the following effects.

First, according to the present invention, the process is simple, the process time is reduced, and the application and removal of the radial emulsion are not required, which is economical compared to the conventional process, and there is no need to process the aramid filament from the core tube, have.

Secondly, according to the present invention, aramid staple fibers having excellent winding property can be obtained by using aramid filaments containing a sufficient amount of water and having low crystallinity.

Aramid staple fibers having excellent winding properties can be used in various fields such as protective clothing, gloves, and fire fighting clothing.

FIG. 1 is a schematic view of a process for producing aramid staple fibers according to an embodiment of the present invention.
2 is a schematic view of a process for manufacturing an aramid filament according to an embodiment of the present invention.

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.

The "spinning speed" used in the present invention means the moving speed of the filament after the solidification process.

As used herein, the term "staple" means staple fibers formed by gathering a plurality of staples.

As used herein, "staple 1 strand" means the minimum unit of mono staple fibers.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view of a process for producing aramid staple fibers according to an embodiment of the present invention.

As shown in FIG. 1, the present invention can roughly be divided into a process for producing the aramid filament 10 and a process for producing the aramid staple fiber using the produced aramid filament 10.

The aramid filament 10 can be produced from the following process.

First, an aromatic polyamide polymer is prepared. The aromatic polyamide polymer may be prepared by dissolving an aromatic diamine in a polymerization solvent to prepare a mixed solution, and adding aromatic diacid to the prepared mixed solution to polymerize.

Then, filaments can be produced. The filaments can be prepared by spinning the prepared spinning dope made of aromatic polyamide polymer in sulfuric acid using a spinneret 110 and then solidifying in a coagulation bath 120 through an air gap.

Subsequently, the sulfuric acid remaining in the filament obtained by passing through the water bath 130 is removed. The sulfuric acid remaining in the filament can be removed through a washing process using water or a mixed solution of water and an alkali solution. The washing step may be performed in multiple stages.

Next, the aramid filament 10 can be manufactured by controlling the water content of the washed filament. Since the filament that has been washed as described above contains excessive moisture, it is possible to remove water from the washed filament and adjust it to have a predetermined moisture content. A method for removing moisture from the washed filament can be performed by various methods, for example, using a drying roller 140 set at a low temperature.

The aramid filament 10 may have an elastic modulus of 300 g / d or more. That is, the aramid filament 10 has a high modulus of elasticity as it has a rigid molecular structure, and thus has a very high flexural modulus.

Such an aramid filament 10 may comprise any compound comprising an aromatic structure and linked with an amide group. For example, the aramid filament 10 may be a para aromatic polyamide, a meta-aromatic polyamide, an aromatic polyamide copolymerized with an aromatic compound having a substituent, or a mixture thereof. Particularly, para-aromatic polyamides have properties of high tensile strength and modulus of elasticity as they have rigid properties due to straight-line aromatic molecular chains.

The aramid filament 10 may have a moisture content of 5% or more so as to more easily impart crimp to the aramid filament 10 having such a rigid molecular structure. Preferably, the aramid filament 10 may have a moisture content of 10% or more. In addition, the aramid filament 10 may have a moisture content of 25% or less. If the moisture content exceeds 25%, the aramid filament 10 can not maintain a uniform moisture content and accordingly, the filament 10 having uniform physical properties Can be difficult.

The aramid filament 10 may have a low degree of crystallinity. That is, since the aramid filament 10 is not treated at a low temperature as much as possible, the aramid filament 10 has a low degree of crystallization as the density of the molecular chains is decreased.

As described above, the aramid filament 10 having a low degree of crystallinity and a high moisture content can be easily bent by an external force due to a low bending elastic modulus, so that crimping can be easily produced.

Next, the aramid staple fibers are continuously produced using the aramid filament 10 prepared as described above.

As shown in FIG. 1, the production process of the aramid filament 10 and the production process of the aramid staple fiber can be performed in the same apparatus. That is, the produced aramid filament 10 is continuously fed into the manufacturing process of the aramid staple fiber without being wound around the core tube. Since the aramid filament 10 and the aramid staple fibers can be continuously produced, the production amount of the aramid staple fiber can be greatly improved.

Accordingly, the aramid filament 10 can be produced at a spinning speed of 300 to 1000 minutes / meter. If the spinning speed is less than 300 minutes / meter, the production efficiency is not greatly improved and the economical efficiency is lowered. On the other hand, if the spinning speed is more than 1000 minutes / meter, it is difficult to control the production process.

The process for producing the aramid staple fiber from the aramid filament 10 may be performed as follows.

First, the finished aramid filaments 10 are joined together to produce a tow. That is, the bundling rollers 200 are used to bundle the aramid filaments 10 produced from the respective spinning apparatuses 100 to produce bundle-shaped tows. Since each aramid filament 10 manufactured through the spinning device 100 has a small total fineness in thickness, it can be easily crimped as it is easily bent. However, when the aramid staple fiber is produced using only one aramid filament 10 having a small total fineness, productivity may be extremely low. Therefore, the productivity of the aramid staple fiber can be greatly improved by manufacturing the bundle-shaped tow having a large total fineness by combining the respective aramid filaments 10 produced from the respective spinning apparatuses 100.

The tow is then heat treated. That is, as the molecular structure is loosened by heat treatment of the tow, the bending elastic modulus is lowered, so that the following crimping can be easily produced. Such a heat treatment process can be performed through various methods. For example, the tow can be directly heat-treated using a high-temperature roller, and the tow can be indirectly heat-treated by irradiating infrared rays to the tow.

In particular, when the tow is directly heated using the heat treatment unit 400 equipped with the steam generator, since a large amount of water can be applied to the tow together with high temperature heat, the heat efficiency is excellent and moisture acts as a plasticizer. The bending elastic modulus greatly decreases, so that crimping can be easily generated in the tow.

The heat treatment temperature is appropriately adjusted according to the glass transition temperature of the tow. That is, it may be preferable to sufficiently heat the tow at a glass transition temperature or higher. However, when the heat treatment is carried out at an excessive temperature, the crystal structure of the tow may greatly change, so that the physical properties may be lowered, so it is desirable to avoid the excessive high temperature treatment.

On the other hand, the first emulsion can be applied to the tow before the heat treatment of the tow. The process of applying the emulsion to the tow can be carried out through various methods. For example, as shown in FIG. 1, the emulsion is applied to the tow by passing the toe through the emulsion bath 300, Emulsion can be given.

As described above, the toe imparted with the emulsion is improved in the house properties and the frictional force is decreased, so that the subsequent process can proceed smoothly and the production efficiency can be greatly improved.

The content of the anti-fogging agent is appropriately given according to the total fineness of the tow. If the content of the emulsion for the room is insufficient, the crimp can not be smoothly expressed. However, when the emulsion content of the cushion is excessive, the cuff becomes harder due to the hardening of the tow after the heat treatment, Can be degraded.

Accordingly, it is preferable to treat the spinning emulsion so as to contain 0.1 to 1% by weight in the final aramid staple fiber. Generally, in the process until the final aramid staple fiber is obtained after treating the spinning emulsion, A sufficient amount of spinning emulsion should be imparted to the filament, preferably 0.5 to 2% by weight of filaments being treated with a spinning emulsion at a final aramid staple fiber of 0.1 to 1 It is preferable that a spinning oil emulsion can be contained in an amount of 1 wt%.

The heat treated tow is then crimped. The process of imparting crimp to the tow can be performed by various methods. For example, a gear box equipped with a gear roller formed on the surface of a saw blade, or a stuffer box equipped with a doctor blade may be used to apply crimping to the heat treated tow, but the present invention is not limited thereto.

The number of crimps of the crimped tow thus produced is preferably from 3 to 15 crimps per inch. If the number of the crimp is less than 3 / inch, the bulge resistance is low, and the feeling and appearance are lowered. If the crimp number exceeds 15 / inch, the bulge resistance is too high and the processability is deteriorated. The crimp number is measured in accordance with ASTM D3937: 2000.

Then, the crimped tow is cut to a predetermined length. That is, the tow is cut to a certain length according to the required product to produce aramid staple fiber. The cutting process can be performed in a tensioned state to obtain short fibers having a uniform length. The length of the obtained aramid staple fiber is preferably 30 to 150 mm. If the length is less than 30 mm or more than 150 mm, the spinning process can not proceed smoothly.

On the other hand, after the step of applying crimp to the tow, the crimped tow 20 may be provided with a second emulsion. That is, the second spinning emulsion can be applied to the crimped tow 20 to smoothly carry out the subsequent process by replenishing the spinning emulsion lost in the heat treatment process and the crimping process. Since the second spinning oil emulsion application step is a dimension for replenishing the spinning oil emulsion, it can be simply performed using the emulsion nozzle 600.

In addition, the second spinning emulsion can be treated to dry the crimped tow 20. That is, the crimped tow 20 is passed through the drying unit 700 to improve the shape stability of the crimped tow 20 and to control the viscosity of the emulsion to smoothly carry out the cutting process.

The aramid staple fiber prepared as described above may have a crimp angle of 70 to 140 [deg.]. Aramid staple fibers having such a low crimp angle range have excellent crimping properties, and aramid staple fibers having such excellent crimping properties can be used in various fields such as protective clothing, gloves, and fire fighting clothing.

Further, by producing aramid staple fibers continuously without winding the aramid filaments 10, the following effects can be obtained. First, by using the same device, the process can be simplified, and productivity and production efficiency can be improved, so that the economical efficiency can be improved. Further, since the bending modulus of elasticity of the aramid filament 10 is low, aramid staple fibers having excellent crimping properties can be obtained.

Further, the aramid staple fiber has a tensile strength of 10 g / d or more. The aramid staple fiber having such excellent tensile strength can be used for a protective clothing requiring a high tensile strength.

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

Example One

20% by weight of the spinning dope prepared by dissolving the para aromatic polyamide polymer in a 100% sulfuric acid solvent was radiated through the spinneret 110 and then solidified in the coagulation bath 120 through the air gap to produce a filament, Sulfuric acid was removed from the filament through a water bath 130, and water was removed by a drying roller 140 maintained at 50 ° C to produce an aramid filament 10 having a water content of 15%.

40 aramid filaments 10 manufactured through each of the above-described spinning apparatuses 100 are successively manufactured by using a collecting roller 200 and the tow is impregnated in an emulsion bath 300 containing a silicone emulsion After the first emulsion of 1% by weight was applied, the tow was heated in the heat treatment part 400 in which steam at a temperature of 130 캜 and a pressure of 3 psi was injected.

The heated tow was then passed through a crimp portion 500 equipped with a stuffing box to produce a crimped tow having an 8 / inch crimp number.

Next, a second silicone emulsion was applied to the crimped tow using an emulsion nozzle 600, and then dried by passing through a drying unit 700 maintained at 60 ° C.

Then, the dried tow was cut into a length of 50 mm through the cut portion 800 in a state where the tension was applied, thereby producing an aramid staple fiber.

Example 2 to 4

The aramid staple fibers were produced in the same manner as in Example 1, except that the water content of the aramid filament 10 was changed to 5%, 20%, and 25%, respectively, in Example 1 described above.

Comparative Example

The aramid staple fibers were prepared in the same manner as in Example 1, except that the aramid filaments (10) were produced in the above-described Example 1, and then the aramid staple fibers were discontinuously produced.

In detail, the filament is dried, and then the filament is heat-treated using a heat treatment roller (not shown) maintained at a temperature of 180 ° C. to produce an aramid filament 10 having a moisture content of 3% The 40 bobbins were mounted on a creel, and the aramid filaments 10 were then discharged from the bobbin and supplied to the converging roller 200. Thereafter, the same processes as in Example 1 were performed The aramid staple fibers were discontinuously produced from the aramid filament (10).

The properties of the aramid staple fibers obtained by the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

Aramid staple Fiber Crimp angle (°) measurement

The crimp angle of the aramid staple fiber is measured by the following method.

1) randomly sample 10 staples from the manufactured aramid staple fibers.

2) Condition the sampled 10 staples for 24 hours at a temperature of 20.0 占 2.0 占 폚 and a relative humidity of 65.0 占 4.0%.

3) Take staples one by one in each of the conditioned 10 staples to sample 10 staple strands in all.

4) Each of the 10 staple strands sampled was placed on a slide glass, and the staple strand was covered with the cover glass on the slide glass in a state where the staple strand was not shaken, and then the slide glass was peeled off at 20.0 ± 2.0 ° C. and 65.0 ± 4.0% And allowed to stand for 24 hours.

5) Ten consecutive bending points at the center portion of each staple fiber staple were photographed using a digital microscope (sometech, KOREA, SV-35) and an image analysis program (sometech, KOREA, ITPlus 4.01.01) Were used to measure the angles of the 10 bending points.

6) Take the remaining 6 values except for the maximum of 2 and the minimum of 10 of the measured angles.

7) After collecting the six angles measured from each staple strand, calculate the average value of 60 angles in total and use this as the crimp angle.

division Crimp angle (°) Example 1 110 Example 2 134 Example 3 106 Example 4 103 Comparative Example 145

100: Spinning device 200: Focussing roller
300: Emulsion bath 400: Heat treatment unit
500: crimp portion 600: emulsion nozzle
700: Drying section 800: Cutting section
110: Detention 120: Coagulation bath
130: water tank 140: drying roller
10: filament 20: crimped tow

Claims

Producing an aramid filament having a modulus of elasticity of 300 g / d or more;
Continuously joining the aramid filaments without winding the aramid filaments to produce a tow;
Heat treating the tow;
Subjecting the heat treated tow to crimping; And
And cutting the crimped tow,
Wherein the heat treatment is performed by directly heating the tow with steam. &Lt; RTI ID = 0.0 > 11. < / RTI >

The method according to claim 1,
Wherein the aramid filament comprises a para-aromatic polyamide.

3. The method of claim 2,
Wherein the aramid filament has a moisture content of 5% or more.

The method according to claim 1,
Further comprising the step of applying a first emulsion to the tow prior to the step of heat treating the tow.

The method according to claim 1,
Further comprising the step of applying a second emulsion to the crimped tow after the step of applying crimp to the tow.

6. The method of claim 5,
Further comprising the step of drying the crimped tow imparted with the second emulsion.

The method according to claim 1,
In the aramid filament manufacturing process,
A step of discharging the spinning dope through a spinneret;
Solidifying the discharged spinning dope to produce a filament;
Washing the filament with water; And
And adjusting the water content of the filament to 10% or more and 25% or less.

The method according to claim 1,
Wherein the aramid staple fiber has a tensile strength of 10 g / d or more.

The method according to claim 1,
Wherein the aramid staple fiber comprises 0.01 to 1% by weight of a spinning emulsion.

The method according to claim 1,
Wherein the aramid staple fibers have a crimp number of 3 to 15 / inch.

The method according to claim 1,
Wherein the aramid staple fibers have a length of 30 to 150 mm.

The method according to claim 1,
Wherein the aramid staple fiber has a crimp angle of 70 to 140 °.

The method according to claim 1,
Wherein the aramid filament is produced at a spinning speed of 300 to 1000 m / min.