WO2020232931A1 - Preparation method for long continuous electrospun polyacrylonitrile nanofiber yarn, and application thereof - Google Patents

Abstract

A preparation method for a long continuous electrospun polyacrylonitrile nanofiber yarn, comprising the following steps: a. dissolving a polyacrylonitrile raw material into a polar solvent in mechanical stirring to obtain a uniform spinning solution; b. preparing the polyacrylonitrile solution in step a into a polyacrylonitrile non-woven fabric in an electrospinning machine; c. slitting the non-woven fabric in step b into elongated strips having a width of 0.5-6 cm; d. drawing the elongated strips in step c in a water bath at 80-95ºC at a draw ratio of 2-5 times, and then drawing same in air at 110-150ºC at a draw ratio of 3-10 times to obtain a fiber bundle having a highly oriented inner fiber; and e. twisting the fiber bundle in step d to obtain a long continuous electrospun polyacrylonitrile nanofiber yarn having a length of not less than 2,000 m.

Description

Preparation method and application of electrospun polyacrylonitrile nanofiber continuous long yarn Technical field

The invention relates to the field of polymer fiber continuous long yarns, in particular to a preparation method and application of electrospun polyacrylonitrile nanofiber continuous long yarns.

Background technique

Polyacrylonitrile fiber, commonly known as acrylic or man-made wool, is a commonly used man-made fiber. It can replace wool or blend with wool to make woolen fabrics. It has a good warmth retention effect. It also has excellent weather resistance, light resistance, and outdoor exposure. One year later, the strength dropped by only 20%, so it is often used to make curtains, tarpaulins, etc.

Electrospinning is a special fiber manufacturing process. It has been used more and more to prepare nanofiber materials in the past ten years. Its working method is: spray polymer solution or melt in a high-voltage electric field. It is solidified during a certain running distance, and finally the spinning is received by the receiving device. Because the electrospinning process is simple and convenient, various forms of fibers can be produced according to needs, such as solid fibers, hollow fibers, and core-shell structure fibers, so it has broad prospects in many fields.

However, the current electrospinning technology is only used to make nonwovens or spray a thin layer of nano cobweb on industrial nonwovens (generally with an area density of about 1g/m ² ), and it can also produce discontinuous, relatively dense linear For large coarse yarns, there is no technology in the world that can continuously produce ultra-small linear density or ultra-high count electrospun nanofiber yarn. The linear density of conventional fiber yarn is below 6Tex, and the yarn count is generally less than 150, most of which are below 100.

Summary of the invention

In order to solve the above technical problems, the first aspect of the present invention provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Dissolve the polyacrylonitrile raw material in a polar solvent under mechanical stirring to obtain a uniform spinning solution;

b. The polyacrylonitrile solution in step a is made into a polyacrylonitrile non-woven fabric in an electrostatic spinning machine;

c. Cut the nonwoven fabric in step b into slender strips with a width of 0.5-6 cm;

d. The elongated strip in step c is drawn in a water bath at 80-95°C with a draft ratio of 2 to 5 times, and then at 110-150°C in air, with a draft ratio of 3 to 10 times , To obtain a fiber bundle with highly oriented internal fibers;

e. Twist the fiber bundle in step d to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn with a length of not less than 2000 meters.

As a preferred technical solution, the polar solvent in the step a is selected from N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide One or more of them.

As a preferred technical solution, the water bath drafting and air drafting in the step d are 5-roll drafting.

As a preferred technical solution, the unwinding speed of the water bath drafting in step d is 2-8 m/min.

As a preferred technical solution, the unwinding speed of air drafting in the step d is 3-8 m/min.

As a preferred technical solution, the fiber orientation of the fiber bundle in the step d is 90%-95%.

As a preferred technical solution, the unwinding speed of twisting in step e is 5-50 m/min.

As a preferred technical solution, the twist in the step e is 500-1500 twists/meter.

The second aspect of the present invention provides an electrospun polyacrylonitrile nanofiber continuous long yarn, which is prepared by the above-mentioned preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn.

The third aspect of the present invention provides an application of electrospun polyacrylonitrile nanofiber continuous long yarn, which is used for pure spinning or blended spinning to weave light and warm high-end fabrics.

Beneficial effects: The invention provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn. The mechanical properties of the polyacrylonitrile fiber are enhanced by the drafting operation, and the continuous production is possible. The length of the obtained long yarn Not less than 2000 meters, with a public count of more than 500, the yarn can be used for pure spinning or blending to obtain light, warm, and durable high-end fabrics.

Detailed ways

The content of the present invention can be further understood in combination with the following detailed description of the preferred implementation method of the present invention and the included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. If the definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition of the term provided in this application shall prevail. As used herein, unless the context clearly indicates otherwise, features that do not limit singular and plural forms are also intended to include plural features. It should also be understood that, as used herein, the term "prepared from" is synonymous with "comprising", "comprising", "including", "having", "including" and/or "including", when used in this specification When used in, it means the stated composition, step, method, product or device, but does not exclude the presence or addition of one or more other compositions, steps, methods, products or devices. In addition, when describing the embodiments of the present application, the use of "preferred", "preferred", "more preferred", etc. refers to the embodiments of the present invention that can provide certain beneficial effects in some cases. However, under the same or other circumstances, other embodiments may also be preferable. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

In order to solve the above technical problems, the present invention provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Dissolve the polyacrylonitrile raw material in a polar solvent under mechanical stirring to obtain a uniform spinning solution;

b. The polyacrylonitrile solution in step a is made into a polyacrylonitrile non-woven fabric in an electrostatic spinning machine;

c. Cut the nonwoven fabric in step b into slender strips with a width of 0.5-6 cm;

d. The elongated strip in step c is drawn in a water bath at 80-95°C with a draft ratio of 2 to 5 times, and then at 110-150°C in air, with a draft ratio of 3 to 10 times , To obtain a fiber bundle with highly oriented internal fibers;

e. Twist the fiber bundle in step d to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn with a length of not less than 2000 meters.

Step a

The purpose of step a is to prepare a polymer solution suitable for electrospinning. Since polyacrylonitrile contains a large number of polar cyano groups, choosing a suitable polar solvent will help to prepare a spinning solution with suitable concentration and adjustable viscosity. Solution.

Step a: Dissolve the polyacrylonitrile raw material in a polar solvent under mechanical stirring to obtain a uniform spinning solution.

In some preferred embodiments, the polyacrylonitrile raw material and the polar solvent are added to a stainless steel reactor together, and dissolved under mechanical stirring to obtain a uniform polyacrylonitrile solution for spinning.

The raw material of polyacrylonitrile in the present invention is not particularly limited, and can be commercially available, with CAS number 25014-41-9.

In some embodiments, the polar solvent in step a is selected from N,N-dimethylformamide (CAS No. 68-12-2), N-methylpyrrolidone (CAS No. 872-50- 4) A mixture of one or more of dimethyl sulfoxide (CAS number: 67-68-5) and N,N-dimethylacetamide (CAS number: 127-19-5).

Both dimethyl sulfoxide and N-methyl pyrrolidone are solvents with better properties for dissolving polyacrylonitrile, and dimethyl sulfoxide is non-toxic, but the boiling points of both are above 200 ℃, and the spun yarn is not easy to dry. The adhesion between each other is serious. The boiling point of N,N-dimethylformamide is the lowest among several listed solvents and has the best solubility. Although N,N-dimethylacetamide has relatively poor solubility, it has the advantage of low toxicity. It can be compounded with N,N-dimethylformamide to make a mixed solvent that is good for spinning.

In some preferred embodiments, the polar solvent in the step a is N,N-dimethylformamide and/or N,N-dimethylacetamide; further preferably, the N,N- Dimethylformamide and N,N-dimethylacetamide; furthermore, the mass ratio of N,N-dimethylformamide and N,N-dimethylacetamide is 4:1.

The concentration of the spinning solution determines the viscosity of the solution. If the viscosity is too high, the electrostatic force needs to overcome a greater surface tension, making the spinning diameter too large or even impossible to spin; and a too small viscosity will make the spinning too thin. The strength is insufficient, or beads may appear on the spinning. In some preferred embodiments, the mass concentration of the solution in step a is 12-22%; further preferably, the mass concentration of the solution in step a is 13-18%.

In some preferred embodiments, the absolute viscosity of the solution in the step a is 1.5 to 5 Pa.S; further preferably, the absolute viscosity of the solution in the step a is 2 to 4 Pa.S.

Proper dissolution temperature can speed up the dissolution rate and improve the processing efficiency on the one hand, and on the other hand can reduce the solubility of the gas in the solution and remove the gas in the solution. In some preferred embodiments, the dissolution temperature in the step a is 30-55°C, and the stirring time is 4-10 hours; further preferably, the dissolution temperature in the step a is 38-48°C, and the stirring time It is 6 to 9 hours.

Step b

The purpose of step b is to make polyacrylonitrile from a solution into a nonwoven fabric. In this process, the polymer solution is sprayed into a strong electric field. Under the action of the electric field, the sprayed droplets change from a spherical shape to a Taylor cone, from the tip of the Taylor cone Extend the micro jets, after running for a certain distance, the jets solidify into fiber filaments, which are collected by the stainless steel mesh belt to obtain a non-woven fabric.

Step b: The polyacrylonitrile solution in step a is made into a polyacrylonitrile nonwoven fabric in an electrospinning machine.

In some preferred embodiments, the polyacrylonitrile solution is injected into the spinneret of the electrospinning machine, jet-spinned in a high-voltage electric field, and collected by a stainless steel mesh belt to obtain an electrospun polyacrylonitrile nonwoven fabric.

The voltage of the electric field will affect the shape of the ejected droplets. Too small a voltage cannot cause the spherical droplets of the spinneret to form a Taylor cone, while an excessively high voltage will cause the formed Taylor cone to retreat or even return to the inside of the spinneret, resulting in A large number of beads appear in the spun fiber. In some preferred embodiments, the DC voltage of the high-voltage electric field in the step b is 30-50 kV; further preferably, the DC voltage of the high-voltage electric field in the step b is 40-45 kV.

The distance between the spinneret and the stainless steel mesh belt collector needs to ensure that the jet can be solidified during operation without adhesion, and an improper receiving distance will cause beads to appear in the spinning fiber. In some preferred embodiments, the distance between the spinneret and the stainless steel mesh belt collector in step b is 25 to 55 cm; further preferably, the distance between the spinneret and the stainless steel mesh belt collector is 28 to 35 cm.

The running speed of the stainless steel mesh belt can affect the aperture and thickness of the non-woven fabric, and then affect the strength of the long yarn processed from the non-woven fabric. In some preferred embodiments, the running speed of the stainless steel mesh belt in the step b is 1 to 5 m/min; further preferably, the running speed of the stainless steel mesh belt is 2 to 4 m/min.

In some preferred embodiments, the diameter of spinning in the step b is 100 to 1500 nanometers; further preferably, the diameter of spinning in the step b is 100 to 500 nanometers.

Step c

The purpose of step c is to pre-treat the polyacrylonitrile nonwoven fabric into a form suitable for further processing.

Step c: Cut the nonwoven fabric in step b into thin strips with a width of 0.5-6 cm.

The width of the cut sliver will affect the subsequent further processing. Too narrow cuts are not conducive to continuous production, making the final yarn fragile and unable to reach the desired length to obtain long yarns; and too wide cuts are difficult to process internally. Fiber bundles with highly oriented fibers. In some preferred embodiments, the width of the elongated strip in the step c is 0.5-6 cm; further preferably, the width of the elongated strip is 2-5.5 cm.

Step d

The purpose of step d is to obtain a fiber bundle length sufficient to produce a continuous long-thread yarn through the drafting treatment, on the other hand, to change the orientation of the internal fibers, so that the strength of the fiber bundle in the orientation direction is greatly increased.

Step d: The slender strips in step c are drawn in a water bath at 80-95°C with a draft ratio of 2 to 5 times, and then at 110-150°C in air, with a draft ratio of 3-10 To obtain a fiber bundle with highly oriented internal fibers.

In some preferred embodiments, the water bath drafting and air drafting in step d are 5-roll drafting.

In some preferred embodiments, the unwinding speed of the water-bath drafting is 2-8 m/min; further preferably, the unwinding speed of the water-bath drafting is 4-7 m/min.

In some preferred embodiments, the unwinding speed of the air drafting is 3-8 m/min; further preferably, the unwinding speed of the air drafting is 4-7 m/min.

In some preferred embodiments, the fiber orientation of the fiber bundle in the step d is 90%-95%.

Step e

The purpose of step e is to make the fiber bundle into a long yarn by twisting. After the twisting, the outer fiber and the inner fiber squeeze to generate pressure, so that the yarn obtains friction along the fiber length direction, and the fiber strip is fixed in the longitudinal direction. After the yarn is formed, the fibers have improved properties such as strength, elongation, gloss, and hand feeling.

Step e: Twist the fiber bundle in step d to obtain a continuous long electrospun polyacrylonitrile nanofiber yarn with a length of not less than 2000 meters.

In some preferred embodiments, the unwinding speed of twisting in the step e is 5-50 m/min; further preferably, the unwinding speed of the twisting is 20-40 m/min.

In some preferred embodiments, the twist of the twisting in the step e is 500 to 1500 twists/meter; further preferably, the viscosity of the twisting is 800 to 1200 twists/meter.

Compared with other fibers, the strength of polyacrylonitrile nanofibers is lower. In addition to the excellent weather resistance and heat preservation properties of polyacrylonitrile, the strength of polyacrylonitrile fibers after high drafting is further improved, which broadens its applications Scope, after the fiber is drawn and twisted, it can continuously produce long-thread yarn, and then purely or blend other fibers to obtain light, warm, soft and comfortable high-end fabrics.

Example

The technical solutions of the present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited to the embodiments.

Example 1

Embodiment 1 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 135℃, unwinding speed of 6 m/min, draft ratio of 6 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 2

Embodiment 2 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and N,N-dimethylformamide into a stainless steel reactor and mechanically stir and dissolve. The dissolution temperature is 43°C and the stirring time is 8 hours. The quality of the polyacrylonitrile solution for spinning The concentration is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 135℃, unwinding speed of 6 m/min, draft ratio of 6 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 3

Embodiment 3 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and N,N-dimethylacetamide into a stainless steel reactor and mechanically stir and dissolve, the dissolution temperature is 43℃, the stirring time is 8 hours, and the quality of the polyacrylonitrile solution for spinning The concentration is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 135℃, unwinding speed of 6 m/min, draft ratio of 6 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

The nanofiber bundle obtained in step d is twisted to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 4

Embodiment 4 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 2 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 135℃, unwinding speed of 6 m/min, draft ratio of 6 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 5

Embodiment 5 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 5.5 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 135℃, unwinding speed of 6 m/min, draft ratio of 6 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 6

Embodiment 6 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strips in step c are drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 5 times to obtain an electrospun polyacrylonitrile fiber bundle;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 7

Embodiment 7 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 2 times, and then it is subjected to 5-roll air drafting at a temperature of 135°C, unwinding speed of 6 m/min, draft ratio of 3 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 8

Embodiment 8 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The slender strip in step c is drawn in a 5-roll water bath at a temperature of 88°C, an unwinding speed of 6 m/min, and a draft ratio of 5 times, and then it is subjected to 5-roll air drafting at a temperature of 135°C, unwinding speed of 6 m/min, draft ratio of 10 times, to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 9

Embodiment 9 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 80°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 110°C, unwinding speed of 6 m/min, draft ratio of 6 times to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Example 10

Embodiment 10 provides a preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, including the following steps:

a. Add the polyacrylonitrile raw material and the mixed solvent composed of N,N-dimethylformamide and N,N-dimethylacetamide into a stainless steel reaction kettle with mechanical stirring to dissolve, the N,N-dimethylformamide The mass ratio of formamide and N,N-dimethylacetamide is 4:1, the dissolution temperature is 43°C, the stirring time is 8 hours, and the mass concentration of the polyacrylonitrile solution for spinning is 15%;

b. Inject the solution obtained in step a into the spinning device of the electrostatic spinning machine, spray spinning in a high-voltage electric field with a DC voltage of 42kV, and collect the electrospun polyacrylonitrile nonwoven fabric with a stainless steel mesh belt. The spacing of the stainless steel mesh belt collector is 33 cm, the running speed of the stainless steel mesh belt is 3 m/min, and the spinning diameter is 150 nanometers;

c. Cut the nonwoven fabric obtained in step b into slender strips with a width of 4 cm;

d. The elongated strip in step c is drawn in a 5-roll water bath at a temperature of 95°C, an unwinding speed of 6 m/min, and a draft ratio of 3 times, and then it is subjected to 5-roll air drafting at a temperature of 150°C, unwinding speed of 6 m/min, draft ratio of 6 times to obtain electrospun polyacrylonitrile fiber bundle with highly oriented internal fibers;

e. Twist the nanofiber bundle obtained in step d to more than 2000 meters, the unwinding speed is 25 meters/minute, and the twist is 900 twists/meter, to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn.

Performance evaluation

The electrospun polyacrylonitrile nanofiber continuous long yarn obtained in Examples 1-10 was tested for common count, tensile strength, Young's modulus, and elongation at break.

1. Public count: take 1000 meters of yarn and weigh its gram weight, public count=1000/gram weight, the results are shown in Table 1.

2. Tensile strength, Young's modulus, elongation at break: Tested with an electronic universal tensile machine, and the results are shown in Table 1.

Table 1

To	Public number	Tensile Strength	Young's modulus	Elongation at break
Example 1	740	15cN/dtex	298cN/dtex	11%
Example 2	720	14.5cN/dtex	290cN/dtex	12%
Example 3	660	12cN/dtex	246cN/dtex	19%
Example 4	760	3cN/dtex	84cN/dtex	12%
Example 5	700	13cN/dtex	260cN/dtex	14%
Example 6	450	6cN/dtex	108cN/dtex	32%
Example 7	520	11.5cN/dtex	223cN/dtex	27%
Example 8	800	8cN/dtex	130cN/dtex	10%
Example 9	630	10cN/dtex	194cN/dtex	twenty two%
Example 10	600	9.5cN/dtex	172cN/dtex	17%

By comparing Examples 1-10, it can be known that the preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn provided by the present invention can produce high count long yarn with a length of more than 2000 meters, and at the same time improve the polyacrylonitrile fiber The mechanical properties.

Finally, it is pointed out that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in this invention. Within the scope of protection of the invention.

Claims (10)

1. A preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn, which is characterized in that it comprises the following steps:

   a. Dissolve the polyacrylonitrile raw material in a polar solvent under mechanical stirring to obtain a uniform spinning solution;

   b. The polyacrylonitrile solution in step a is made into a polyacrylonitrile non-woven fabric in an electrostatic spinning machine;

   c. Cut the nonwoven fabric in step b into slender strips with a width of 0.5-6 cm;

   d. The elongated strip in step c is drawn in a water bath at 80-95°C with a draft ratio of 2 to 5 times, and then at 110-150°C in air, with a draft ratio of 3 to 10 times , To obtain a fiber bundle with highly oriented internal fibers;

   e. Twist the fiber bundle in step d to obtain an electrospun polyacrylonitrile nanofiber continuous long yarn with a length of not less than 2000 meters.
2. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, wherein the polar solvent in the step a is selected from the group consisting of N,N-dimethylformamide, N-methyl A mixture of one or more of pyrrolidone, dimethyl sulfoxide, and N,N-dimethylacetamide.
3. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, characterized in that the water bath drafting and air drafting in the step d are 5-roll drafting.
4. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, wherein the unwinding speed of the water bath drafting in the step d is 2-8 m/min.
5. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, wherein the unwinding speed of air drafting in step d is 3-8 m/min.
6. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, characterized in that the fiber orientation of the fiber bundle in the step d is 90%-95%.
7. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, wherein the unwinding speed of twisting in step e is 5-50 m/min.
8. The preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 1, wherein the twist in the step e is 500 to 1500 twists/meter.
9. An electrospun polyacrylonitrile nanofiber continuous long yarn, characterized in that it is prepared by the preparation method of electrospun polyacrylonitrile nanofiber continuous long yarn according to any one of claims 1-8.
10. The electrospun polyacrylonitrile nanofiber continuous long yarn according to claim 9, characterized in that it can be used for pure spinning or blended spinning to weave light and warm high-end fabrics.