CN113774515A

CN113774515A - Cellulose-polyacrylonitrile blended fiber and preparation method and application thereof

Info

Publication number: CN113774515A
Application number: CN202111079224.2A
Authority: CN
Inventors: 宾月珍; 陈秋杉; 曲美洁; 王海
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2021-09-15
Filing date: 2021-09-15
Publication date: 2021-12-10

Abstract

The invention belongs to the technical field of moisture-absorbing and heating materials, and particularly relates to cellulose-polyacrylonitrile blended fiber and a preparation method and application thereof. The invention blends cellulose and polyacrylonitrile and prepares the cellulose-polyacrylonitrile blended fiber by a spinning method. The results of the examples show that the cellulose-polyacrylonitrile blended fiber prepared by the preparation method provided by the invention has the highest moisture absorption and heat generation temperature of 4.9 ℃ and the highest elongation at break of 25% under different humidity, and has excellent moisture absorption and heat generation performance and mechanical performance.

Description

Cellulose-polyacrylonitrile blended fiber and preparation method and application thereof

Technical Field

The invention belongs to the technical field of moisture-absorbing and heating materials, and particularly relates to cellulose-polyacrylonitrile blended fiber and a preparation method and application thereof.

Background

In recent years, foreign researchers have conducted a great deal of research on the hygroscopic exothermic properties of fibers. In research, most of the research on the moisture-absorbing and heat-generating fibers is a chemical modification method. Huhaibo et al prepared a crosslinked carboxymethyl viscose fiber as a hygroscopic heating fiber by a surface post-treatment method. Fujimoto prepares a polyacrylonitrile-based moisture-absorbing heating fiber by a method of hydrolysis and crosslinking. Lim et al grafted hydrolyzed starch onto polyacrylonitrile (HSPAN) to obtain a superabsorbent fiber with improved moisture absorption and heat generation properties. However, these studies are rarely applied to mass production, because the spinning performance of the chemically modified raw material is far from that of the original raw material, and continuous production is difficult. Alternatively, the modification method is difficult to commercialize because of its low production efficiency.

At present, the existing moisture-absorbing and heat-generating fibers are composite textile fiber yarns formed by secondary spinning processes such as twisting of cellulose fibers and derivatives thereof (such as viscose fibers, cuprammonium fibers or acetate fibers) and man-made chemical fibers (such as polyester or polyacrylonitrile) from the aspect of components.

Disclosure of Invention

In view of the above, the present invention aims to provide a cellulose-polyacrylonitrile blended fiber, and a preparation method and an application thereof, and the cellulose-polyacrylonitrile blended fiber with excellent moisture absorption and heat generation properties is prepared by blending cellulose and polyacrylonitrile.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a preparation method of cellulose-polyacrylonitrile blended fiber, which comprises the following steps:

mixing cellulose, polyacrylonitrile and a mixed solvent to obtain a spinning solution, wherein the mixed solvent is amide and metal chloride;

and spinning, solidifying, drafting and drying the spinning solution in sequence to obtain the cellulose-polyacrylonitrile blended fiber.

Preferably, the mass of the cellulose is 10-30% of the total mass of the polyacrylonitrile and the cellulose.

Preferably, the mass of the cellulose is 1-7.5% of the total mass of the mixed solvent.

Preferably, the mass of the metal chloride is 6-12% of that of the amide; the metal chloride is lithium chloride, potassium chloride or sodium chloride; the amide is dimethylacetamide or dimethylformamide.

Preferably, the mixing comprises the steps of:

dispersing cellulose in amide, and activating to obtain activated cellulose dispersion liquid;

and sequentially adding metal chloride and polyacrylonitrile into the activated cellulose dispersion liquid to obtain the spinning solution.

Preferably, the activation temperature is 100-150 ℃, and the activation time is 0.5-1 h.

Preferably, the inner diameter of the spinneret for spinning is 0.1-0.9 mm, and the spinning speed is 0.2-0.85 mm/s.

Preferably, the coagulating bath used for coagulation is methanol, and the coagulating temperature is 0-10 ℃; the draft multiple of the draft is 100-2000%.

The invention also provides the cellulose-polyacrylonitrile blended fiber prepared by the preparation method in the technical scheme; the diameter of the cellulose-polyacrylonitrile blended fiber is 50-200 mu m, and the length of the cellulose-polyacrylonitrile blended fiber is 10-100 cm.

The invention also provides the application of the cellulose-polyacrylonitrile blended fiber in the technical scheme in temperature and humidity adjusting fabrics.

The invention provides a preparation method of cellulose-polyacrylonitrile blended fiber, which comprises the following steps: mixing cellulose, polyacrylonitrile and a mixed solvent to obtain a spinning solution; spinning, solidifying, drafting and drying the spinning solution in sequence to obtain cellulose-polyacrylonitrile blended fiber; the mixed solvent is dimethyl acetamide and lithium chloride. The invention simultaneously dissolves cellulose and polyacrylonitrile in a mixed solvent to form a spinning solution, and then prepares the cellulose-polyacrylonitrile blended fiber by a spinning method. The cellulose-polyacrylonitrile blended fiber is formed by blending and spinning cellulose and polyacrylonitrile, and the composite textile fiber yarn formed by twisting and other secondary spinning processes of the cellulose fiber and the polyacrylonitrile fiber in the prior art is the fiber yarn formed by compounding the cellulose fiber and the polyacrylonitrile fiber. The cellulose-polyacrylonitrile blended fiber has excellent moisture absorption and heat generation performance and elongation at break, and is an effective substitute for the existing composite twisted yarn. The results of the examples show that the highest moisture absorption and heat generation temperature of the cellulose-polyacrylonitrile blended fiber prepared by the preparation method provided by the invention reaches 4.9 ℃ under different humidity, and the highest breaking elongation rate reaches 25%, which shows that the cellulose-polyacrylonitrile blended fiber prepared by the preparation method provided by the invention has excellent moisture absorption and heat generation performance and mechanical performance.

Drawings

FIG. 1 is a scanning electron microscope image of cellulose-polyacrylonitrile blended fibers of examples 1 to 3 and fibers of comparative examples 1 to 2;

FIG. 2 is a graph of the maximum hygroscopic heating temperatures of the cellulose-polyacrylonitrile blended fibers of examples 1 to 5 and the fibers of comparative examples 1 to 3 at different humidities;

FIG. 3 is an infrared chart showing the maximum hygroscopic heating temperature in an indoor environment at 90% humidity for the cellulose-polyacrylonitrile blended fibers of examples 1 to 5 and the fibers of comparative examples 1 to 3.

Detailed Description

mixing cellulose, polyacrylonitrile and a mixed solvent to obtain a spinning solution; the mixed solvent is amide and metal chloride;

Unless otherwise specified, the present invention does not require any particular source of the starting materials for the preparation, and commercially available products well known to those skilled in the art may be used.

The invention mixes cellulose, polyacrylonitrile and mixed solvent to obtain spinning solution. The type and type of the cellulose are not particularly limited in the present invention, and the type and type of cellulose known in the art can be used. In the examples of the present invention, the cellulose is specifically cellulose having a CAS number of 9004-34-6. In the invention, the particle size of the cellulose is preferably 25-250 μm, and the mass of the cellulose is preferably 10-30% of the total mass of polyacrylonitrile and cellulose, and more preferably 15-25%; the mixed solvent is amide and metal chloride; the amide is preferably dimethylacetamide or dimethylformamide, more preferably dimethylacetamide; the mass of the cellulose is preferably 1-7.5% of the total mass of the mixed solvent, and more preferably 1.5-6%; the metal chloride is lithium chloride, potassium chloride or sodium chloride, and more preferably lithium chloride or potassium chloride; the mass of the metal chloride is preferably 6-12%, more preferably 8-10% of the mass of the amide.

In the present invention, the mixing preferably comprises the steps of:

dissolving cellulose in amide, and activating to obtain activated cellulose dispersion liquid;

The invention dissolves cellulose in amide for activation to obtain activated cellulose dispersion liquid. In the invention, the activation temperature is preferably 100-150 ℃, more preferably 120-150 ℃, and the activation time is preferably 0.5-1 h, more preferably 0.8-1 h.

Because crystal regions formed by the induction of hydrogen bonds in the cellulose molecules and among the cellulose molecules are arranged tightly, the contact between a solvent and the cellulose molecules is hindered.

After the activated cellulose dispersion liquid is obtained, the metal chloride is dissolved in the activated cellulose dispersion liquid which is naturally cooled to 60 ℃ to obtain the cellulose solution. In the invention, the dissolving temperature is preferably 60-80 ℃, and more preferably 60-70 ℃; the dissolving time is preferably 3-10 hours, more preferably 5-6 hours, and the dissolving mode is preferably stirring; the stirring speed is preferably 100-300 rpm, and more preferably 100-200 rpm. In the present invention, when the cellulose is completely dissolved, the solution is in a uniform translucent state.

Because cellulose has a large amount of crystalline fibrillar structures caused by intramolecular and intermolecular hydrogen bonds, the cellulose is difficult to dissolve in a common solvent, and the invention adopts amide and metal chloride as solvents, so that the cellulose can be completely dissolved without degradation, and uniform spinning solution can be obtained.

After the cellulose solution is obtained, polyacrylonitrile is dissolved in the cellulose solution to obtain the spinning solution. In the invention, the dissolving temperature is preferably 60-80 ℃, and more preferably 70-80 ℃; the dissolving time is preferably 3-10 hours, more preferably 5-6 hours, and the dissolving mode is preferably stirring; the stirring speed is preferably 100-300 rpm, and more preferably 100-200 rpm. In the present invention, the solution appears transparent yellow after the pure polyacrylonitrile is dissolved.

After the spinning solution is obtained, the spinning solution is spun by the invention. In the invention, the inner diameter of the nozzle used for spinning is preferably 0.1-0.9 mm, more preferably 0.5-0.7 mm, and the spinning speed is preferably 0.2-0.85 mm/s, more preferably 0.6-0.8 mm/s. The spinning equipment used in the present invention is not particularly limited, and any spinning equipment known in the art may be used.

The essence of the wet spinning forming is the mass transfer and heat transfer process of the double diffusion process, the solvent and salt in the spinning solution trickle diffuse outwards, the coagulant diffuses inwards, and the fiber is formed.

In the invention, the coagulating bath used for coagulation is preferably methanol, and the temperature of coagulation is preferably 0-10 ℃, and more preferably 1-5 ℃.

After solidification is completed, the invention draws the solidified product. In the invention, the equipment used for drafting is preferably a hand-operated stretcher or a continuous spinning device; the drawing is preferably carried out in a hot water bath; the temperature of the hot water bath is preferably 80-95 ℃, more preferably 90 ℃, and the drafting multiple of the drafting is preferably 600-2000%, more preferably 1200-2000%.

In the invention, the process of drawing and orienting the solidified nascent fiber is the process of orientation, crystallization and rearrangement of a fiber structure, the diameter of the fiber is reduced under the action of external force in the drawing process, and the orientation degree of macromolecules along a fiber axis is greatly improved, so that the breaking strength of the fiber is obviously improved.

After the drafting is finished, the fiber obtained after the drafting is dried to obtain the cellulose-polyacrylonitrile blended fiber.

In the invention, the drying temperature is preferably 10-30 ℃, and more preferably 20-25 ℃; the drying time is preferably 12 to 24 hours, and more preferably 12 to 20 hours.

The invention also provides the cellulose-polyacrylonitrile blended fiber prepared by the preparation method in the technical scheme.

The invention also provides application of the cellulose-polyacrylonitrile blended fiber in the technical scheme in preparation of temperature and humidity regulating clothing fabrics. The application method of the cellulose-polyacrylonitrile blended fiber in the preparation of the temperature-adjusting and humidity-adjusting garment fabric is not particularly limited, and the application method known by the technical personnel in the field can be adopted.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

Example 1

Weighing 0.30g of cellulose (with particle size of 25 μm) and 15.64g of dimethylacetamide, heating at 150 ℃ for 1h, and activating to obtain activated cellulose dispersion; then naturally cooling the activated cellulose to 60 ℃, adding 1.36g of lithium chloride into the cooled activated cellulose dispersion, and continuously stirring the activated cellulose dispersion at the temperature of 60 ℃ and at the speed of 200rpm for 6 hours to obtain a cellulose solution;

adding 2.70g of polyacrylonitrile into the cellulose solution, and stirring for 6 hours at 80 ℃ and 200rpm to obtain a spinning solution;

pouring the spinning solution into a 10mL injector, connecting a spinning nozzle (with the inner diameter of 0.7mm) and a propeller, propelling the injector at the speed of 0.65mm/s, solidifying in a methanol solidification bath at the temperature of 5 ℃, drawing the obtained solidified product in a hot water bath at the temperature of 90 ℃, wherein the drawing multiple is 1200%, and drying the drawn fiber at the temperature of 20 ℃ for 12h to obtain the cellulose-polyacrylonitrile blended fiber which is marked as MCC/PAN-1090-1200-.

Example 2

The difference from example 1 is that: the mass ratio of the cellulose to the polyacrylonitrile was 20: 80, namely 0.60 g of cellulose and 2.40g of polyacrylonitrile, and the rest of the contents were consistent with example 1 and recorded as MCC/PAN-2080-.

Example 3

The difference from example 1 is that the mass ratio of cellulose to polyacrylonitrile is 30: 70, i.e. 0.90g cellulose to 2.10g polyacrylonitrile, and the rest is in accordance with example 1 and is marked as MCC/PAN-3070-1200%.

Example 4

The difference from example 2 is that the draft ratio is 600%, and the rest is identical to example 2 and is marked as MCC/PAN-2080-600%.

Example 5

The difference from example 2 is that the draft ratio is 2000%, and the rest is consistent with example 2 and is marked as MCC/PAN-2080-2000%.

Comparative example 1

The difference from example 1 is that only polyacrylonitrile is contained, and the remainder is identical to example 1 and is referred to as PAN-1200%.

Comparative example 2

The difference from example 1 is that only cellulose is contained, and the draft is 130%, and the rest is identical to example 1 and is marked as MCC-130%.

Comparative example 3

The difference from the example 1 is that the draft ratio is 100%, and the rest is consistent with the example 1 and is marked as MCC/PAN-2080-100%.

Testing the performance;

(1) scanning electron microscope:

SEM tests of the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 3 and the fibers prepared in comparative examples 1 to 2 were performed by a COXEM EM EM-30AX PLUS scanning electron microscope (SEM, COMEX, Korea), and the results are shown in FIG. 1, wherein (a) is the polyacrylonitrile fiber prepared in comparative example 1, (b) is the cellulose-polyacrylonitrile blended fiber prepared in example 1, (c) is the cellulose-polyacrylonitrile blended fiber prepared in example 2, (d) is the cellulose-polyacrylonitrile blended fiber prepared in example 3, and (e) is the cellulose fiber prepared in comparative example 2.

As can be seen from FIG. 1, the polyacrylonitrile fiber prepared in comparative example 1 and the cellulose fiber prepared in comparative example 2 have shallow and fine smooth grooves on the surface, while the cellulose-polyacrylonitrile blended fiber prepared in examples 1 to 3 have obvious wrinkles and grooves on the surface. As the proportion of cellulose in the fiber increases, these axial grooves become wider and deeper, and the surface roughness increases greatly. Moreover, this phenomenon enlarges the specific surface area of the fiber, facilitating the adsorption and transfer of moisture.

(2) Moisture absorption and heat generation test:

the cellulose-polyacrylonitrile blended fibers prepared in the examples 1 to 5 and the fibers prepared in the comparative examples 1 to 3 are subjected to a moisture absorption and heat generation test, and the specific operations are as follows: the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 5 and the fibers prepared in comparative examples 1 to 3 were closely arranged and adhered on a hollow cardboard, a test sample with a size of 2 × 2cm was prepared for a moisture absorption and heat release test, the moisture absorption and heat release test was performed at room temperature of 17 ℃ and a humidity of 22%, using a self-made test apparatus (consisting of an infrared imaging camera, a three-neck reactor, a split hygrometer and a humidifier, and conventionally connected), when the humidity in the reactor reached a set value (60% ± 3%, 70 ± 2%, 80 ± 2%, 90 ± 2%), placing the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 5 and the fiber samples prepared in comparative examples 1 to 3 on the middle neck of the reactor, and monitoring the moisture absorption and heat release performance thereof using a FOTRIC thermal infrared imager (FOTRIC, China), the results are shown in table 1 and fig. 2.

TABLE 1 cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 5 and fibers prepared in comparative examples 1 to 3 on the table of highest moisture absorption and heat generation temperatures under different humidities

As can be seen from Table 1, the maximum hygroscopic heating temperature of the cellulose-polyacrylonitrile blended fiber prepared by the preparation method provided by the invention reaches 4.9 ℃ under different humidities.

In fig. 2, (a) is the fiber prepared in comparative example 1, the cellulose-polyacrylonitrile blended fiber prepared in examples 1 to 3, and the fiber prepared in comparative example 2, and (b) is the fiber prepared in comparative example 3, the cellulose-polyacrylonitrile blended fiber prepared in example 4, the cellulose-polyacrylonitrile blended fiber prepared in example 2, and the cellulose-polyacrylonitrile blended fiber prepared in example 5.

As can be seen from fig. 2 (a), the fiber exothermic value has a consistent trend with the change of humidity, i.e., the heating temperature difference increases with the increase of humidity. This is because when the humidity is higher, the fibers are more likely to come into contact with water molecules, and more water molecules absorbed per unit time will result in more heat being released. Under the same humidity environment, the heat release performance of the fiber is improved along with the increase of the proportion of the cellulose in the blended fiber. This is because the cellulose content is increased and more polar groups are exposed on the surface of the fiber, contributing to the absorption of water molecules by the fiber. However, when the cellulose content reaches a certain value, the heating temperature difference of the fiber does not always increase as the cellulose content increases. As can be seen from fig. 2 (b), the cellulose-polyacrylonitrile blended fiber of example 3 has slightly better heat release performance than the pure cellulose fiber of comparative example 2 at the same humidity. SEM photographs of the fiber surface may preliminarily explain this phenomenon, and as can be seen from fig. 1 (d) and (e), the surface of the cellulose-polyacrylonitrile blend fiber of example 3 is rougher than that of the pure cellulose fiber of comparative example 2, the deeper the wrinkles and grooves, the larger the specific surface area, and the more the moisture molecules are contacted and adsorbed. Therefore, the moisture absorption and heat release capacity of the fiber is better than that of pure cellulose fiber.

FIG. 3 is an infrared diagram showing the moisture absorption and heat generation temperatures of the cellulose-polyacrylonitrile blend fibers of examples 1 to 5 and the fibers of comparative examples 1 to 3 in an indoor environment having a humidity of 90% (indoor environment: 16.3 ℃ C., 17.1%). As can be seen from fig. 3, the maximum hygroscopic heat generation temperature of the cellulose-polyacrylonitrile blend fiber of example 3 at 90% humidity was the highest, reaching 21.2 ℃.

(3) And (3) testing mechanical properties:

the mechanical properties of the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 5 and the fibers prepared in comparative examples 1 to 3 were tested by a Linkam tensile tester, the test temperature was set at 20 ℃, the test humidity was set at 23%, the drafting rate of the fibers was 5mm/s, and the original length of the sample between the nips was 15 mm. The test results are shown in table 2.

TABLE 2 mechanical Property data for cellulose-polyacrylonitrile blended fibers prepared in examples 1-5 and fibers prepared in comparative examples 1-3

As can be seen from table 2, the breaking strength and the breaking elongation of the pure cellulose fiber prepared in comparative example 2 were 269.6MPa and 8.6%, respectively, which were lower than 511.5MPa and 18.4% of the pure polyacrylonitrile fiber prepared in comparative example 1. For cellulose-polyacrylonitrile blended fibers, overall, the addition of cellulose reduces the mechanical strength of polyacrylonitrile fibers to some extent, while the elongation at break is increased. The breaking strength of the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 3 was 239.5MPa, 267.1MPa, and 201.2MPa, respectively. Compared with the pure polyacrylonitrile fiber prepared in the comparative example 1, the pure polyacrylonitrile fiber is reduced by about 40-60%, but the pure polyacrylonitrile fiber is basically the same as the pure polyacrylonitrile fiber prepared in the comparative example 1. The elongation at break of the cellulose-polyacrylonitrile blended fibers prepared in examples 1 to 3 were 24.7%, 22.8% and 19.5%, respectively, and were improved by 34%, 24% and 6% respectively as compared with the pure polyacrylonitrile fiber prepared in comparative example 1, and were improved by 187%, 165% and 127% respectively as compared with the pure cellulose fiber prepared in comparative example 2. In contrast to cellulose-polyacrylonitrile blended fibers with the same cellulose content but different draft ratios, the cellulose-polyacrylonitrile blended fiber samples prepared in examples 2, 4 and 5 were taken as examples, and as the draft ratio was increased, the stress-strain behavior was changed from original hard and tough to hard and tough. The breaking strength and the breaking elongation of the cellulose-polyacrylonitrile blend fiber of example 4 were 101.1MPa and 13.9% respectively when the draft was 600%, 267.1MPa and 364.5MPa respectively when the draft was 1200% and 2000%, respectively, and 22.8% and 25% respectively. Compared with the fiber prepared by the comparative example, the breaking strength of the cellulose-polyacrylonitrile blended fiber prepared by the preparation method provided by the invention is reduced, but the breaking elongation is obviously improved to 25% at most. As the draft ratio increases, the degree of orientation of the molecular chains in the direction of the external force increases, which is a cause of the improvement in the breaking strength of the fiber.

Although the present invention has been described in detail with reference to the above embodiments, it is only a part of the embodiments of the present invention, not all of the embodiments, and other embodiments can be obtained without inventive step according to the embodiments, and the embodiments are within the scope of the present invention.

Claims

1. A preparation method of cellulose-polyacrylonitrile blended fiber comprises the following steps:

2. The preparation method according to claim 1, wherein the mass of the cellulose is 10-30% of the total mass of polyacrylonitrile and cellulose.

3. The method according to claim 1, wherein the mass of the cellulose is 1 to 7.5% of the total mass of the mixed solvent.

4. The preparation method according to claim 1 or 3, wherein the mass of the metal chloride is 6-12% of the mass of the amide; the metal chloride is lithium chloride, potassium chloride or sodium chloride; the amide is dimethylacetamide or dimethylformamide.

5. The method of claim 1, wherein the mixing comprises the steps of:

6. The method according to claim 5, wherein the temperature of the activation is 100 to 150 ℃ and the time of the activation is 0.5 to 1 hour.

7. The method of claim 1, wherein the spinneret for spinning has an inner diameter of 0.1 to 0.9mm, and the spinning speed is 0.2 to 0.85 mm/s.

8. The preparation method according to claim 1, wherein the coagulation bath for coagulation is methanol, and the temperature of coagulation is 0 to 10 ℃; the draft multiple of the draft is 100-2000%.

9. Cellulose-polyacrylonitrile blended fiber prepared by the preparation method of any one of claims 1 to 8; the diameter of the cellulose-polyacrylonitrile blended fiber is 50-200 mu m, and the length of the cellulose-polyacrylonitrile blended fiber is 10-100 cm.

10. The application of the cellulose-polyacrylonitrile blended fiber in the temperature and humidity adjusting fabric according to claim 9.