阅读说明：本技术 通过聚合物纳米纤维构筑超轻聚氨酯气凝胶纤维的方法 (Method for constructing ultra-light polyurethane aerogel fiber through polymer nanofiber ) 是由 王栋 尤海宁 梅涛 赵青华 宋银红 吴建美 陈卓 蒋海青 于 2021-09-06 设计创作，主要内容包括：本发明提供了一种通过聚合物纳米纤维构筑超轻聚氨酯气凝胶纤维的方法,通过将聚合物纳米纤维添加到聚氨酯溶液中,对湿法纺丝过程中纤维凝固成型进行调控,冷冻干燥后制得超轻、高弹、多孔的聚氨酯气凝胶纤维。本发明通过添加聚合物纳米纤维,在聚氨酯气凝胶纤维内部形成均匀致密的多孔结构,该结构可实现内部空腔保留空气,含静止空气量大,且通气量小,不易与外部空气交换,制成的纺织品具有更好的保暖效果,可应用于个人热管理,减少能源浪费。聚氨酯气凝胶纤维内部多孔结构和比表面积的增加使得纤维质量轻,为其舒适度和轻薄提供了潜在的应用；且该方法具有连续式的纺丝工艺,简单易实现、易于调控、成本较低、绿色环保、便于工业化生产。(The invention provides a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers. According to the invention, by adding the polymer nano-fibers, a uniform and compact porous structure is formed in the polyurethane aerogel fibers, the structure can realize that the internal cavity retains air, the static air content is large, the ventilation capacity is small, and the air is not easy to exchange with the external air, so that the prepared textile has a better heat-insulating effect, can be applied to personal heat management, and reduces energy waste. The porous structure and the specific surface area in the polyurethane aerogel fiber are increased, so that the fiber is light in weight, and potential application is provided for the comfort, lightness and thinness of the fiber; the method has a continuous spinning process, is simple and easy to realize, easy to regulate and control, low in cost, green and environment-friendly, and convenient for industrial production.)

1. A method for constructing ultralight polyurethane aerogel fibers by using polymer nanofibers is characterized by comprising the following steps:

s1, adding polyurethane into the organic solvent, and stirring until the polyurethane is completely dissolved to obtain a polyurethane solution;

s2, adding the polymer nanofiber into an alcohol solution for dispersion, and shearing by using a high-speed beater to obtain a polymer nanofiber suspension;

s3, centrifuging and drying the polymer nanofiber suspension obtained in the step S2 to obtain polymer nanofiber powder;

s4, fully mixing the polymer nanofiber powder obtained in the step S3 with the polyurethane solution obtained in the step S1, soaking the mixture in an aqueous solution for 20-25 hours after wet spinning, and performing freeze drying treatment to obtain polyurethane aerogel fibers; the mass ratio of the polymer nanofiber powder to the polyurethane is 1 (1-5).

2. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers as claimed in claim 1, wherein in step S1, the mass fraction of polyurethane in the polyurethane solution is 5-25%.

3. The method for constructing ultra-light polyurethane aerogel fibers from polymer nanofibers according to claim 1, wherein in step S2, the polymer nanofibers are one or more of polyolefin, polyester, polyamide, polyvinyl alcohol or copolymer nanofibers.

4. The method for constructing the ultra-light polyurethane aerogel fiber by the polymer nanofibers as claimed in claim 3, wherein the diameter of the polymer nanofibers is 50-1000 nm, and the aspect ratio is not less than 150.

5. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers as claimed in claim 1, wherein in step S4, the freeze-drying process is performed by freezing at-20 to 40 ℃ for 6 to 8 hours and then freeze-drying in a freeze-drying machine for 20 to 25 hours to maintain the internal structure of the polyurethane aerogel fibers.

6. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers as claimed in claim 1, wherein in step S2, the alcohol solution is a mixed solution of water and isopropanol in a volume ratio of (2-4): 1.

7. The method for constructing ultra-light polyurethane aerogel fiber by using polymer nanofibers according to claim 1, wherein in step S4, the coagulation bath used in the wet spinning is an aqueous solution, the injection speed is 8 to 12mL/min, and the winding speed is 1500 to 3500 r/min.

8. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers according to claim 1, wherein in step S4, the polymer nanofiber powder is mixed with the polyurethane solution by ultrasonic mixing for 10-20 min, so that the polymer nanofiber powder is uniformly dispersed in the polyurethane solution.

9. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers according to claim 1, wherein in step S1, the organic solvent is one or more of dimethylformamide, dimethylacetamide, tetrahydrofuran, and dimethylsulfoxide; the stirring mode is mechanical stirring at the temperature of 50-70 ℃.

10. The method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers as claimed in claim 1, wherein the diameter of the polyurethane aerogel fibers is 200 to 800 μm, and the linear density is 10 to 25 tex.

Technical Field

The invention relates to the technical field of polyurethane aerogel fibers, in particular to a method for constructing an ultra-light polyurethane aerogel fiber through polymer nanofibers.

Background

Since the 21 st century, polyurethane and synthetic fiber thereof have been widely used in the fields of clothing, textile, biomedical materials and the like due to the characteristics of high strength, low modulus, high resilience and high elongation at break. Polyurethane fibers have a higher elasticity because the high molecular chains consist of low melting, amorphous "soft" segments as matrix and high melting, crystalline "hard" segments embedded therein. The flexible chain segment has certain cross-linking to form certain netted structure, and has small interaction force and thus great elongation. The bonding force of the molecular chain of the rigid chain segment is larger, and the molecular chain cannot extend without limit, so that high resilience is caused. In addition, foamed products and non-foamed products made of polyurethane are also widely applied to the fields of materials such as transportation, civil engineering and construction, footwear, synthetic leather, aerospace, seat sofas, mattress sponges and the like.

With the wide application of polyurethane fibers in different fields, people put more and higher requirements on the performance of the polyurethane fibers; not only is strength and comfort required, but also certain warmth retention is required; the heat-insulating property of the fabric requires that the static air content of the polyurethane fiber is large and the ventilation capacity is small, so that the exchange with the outside air is avoided, the loss of heat is reduced, and the good heat-insulating effect is kept.

Aerogels are porous nanostructured (mesoporous, small macroporous) materials with high porosity (above 90%) and high specific surface area (at least greater than 100 m)²In terms of/g). Aerogel fibers, which are a simultaneous embodiment of the aerogel 3D network and the fiber geometry, have shown great advantages over natural and synthetic fibers in thermal insulation. Aerogel fibers with ultra-high porosity and ultra-low density are expected to be used in personal thermal management materials to reduce energy waste for heating the entire room and play an important role in reducing energy waste as a whole. However, aerogel fibers generally have a complicated preparation process, and the insulation effect thereof cannot satisfy complicated environments and people's needs.

At present, the methods for preparing and producing polyurethanes are broadly divided into four categories: wet spinning, dry spinning, melt spinning, and chemical reaction spinning. Among them, wet spinning is spinning by dissolving polyurethane in an organic solvent and then molding in a coagulation bath. Although the polyurethane fiber prepared by the wet spinning technology has good elasticity, due to the rapid exchange of the solvent in the coagulating bath, uneven macroporous or flaky structures are easily formed, and the performance and application of the polyurethane fiber are influenced.

In view of the above, the invention is based on a wet spinning technology, adopts a continuous preparation process, and regulates and controls the solidification and forming process of the fibers by adding the nanofiber powder into the spinning solution, so that a fine, compact and uniform porous structure is constructed in the polyurethane fibers through the nanofiber powder, the ultra-light, high-elastic and porous polyurethane aerogel fibers are obtained, the heat retention is obviously improved, and the preparation method has important significance for the application of the aerogel fibers in the aspect of personal heat management materials.

Disclosure of Invention

The invention aims to provide a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers, which is based on a wet spinning technology and adopts a continuous preparation process to add the polymer nanofibers into a polyurethane solution to prepare the ultra-light, high-elasticity and porous polyurethane aerogel fibers. The preparation method is simple and easy to realize, and is convenient for industrial production; and the prepared product has good performance, can be applied to the aspect of personal heat management materials, and plays an important role in reducing energy waste.

In order to achieve the above object, the present invention provides a method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers, comprising the steps of:

s1, adding polyurethane into the organic solvent, and stirring until the polyurethane is completely dissolved to obtain a polyurethane solution;

s2, adding the polymer nanofiber into an alcohol solution for dispersion, and shearing by using a high-speed beater to obtain a polymer nanofiber suspension;

s3, centrifuging and drying the polymer nanofiber suspension obtained in the step S2 to obtain polymer nanofiber powder;

s4, fully mixing the polymer nanofiber powder obtained in the step S3 with the polyurethane solution obtained in the step S1, soaking the mixture in an aqueous solution for 20-25 hours after wet spinning, and performing freeze drying treatment to obtain polyurethane aerogel fibers; the mass ratio of the polymer nanofiber powder to the polyurethane is 1 (1-5).

In a further improvement of the present invention, in step S1, the mass fraction of polyurethane in the polyurethane solution is 5 to 25%.

As a further improvement of the present invention, in step S2, the polymer nanofibers are one or more of polyolefin, polyester, polyamide, polyvinyl alcohol or copolymer nanofibers.

As a further improvement of the invention, the diameter of the polymer nanofiber is 50-1000 nm, and the length-diameter ratio is more than or equal to 150.

As a further improvement of the invention, in step S4, the freeze-drying treatment is to freeze the polyurethane aerogel fiber at a temperature of-20 to 40 ℃ for 6 to 8 hours, and then the polyurethane aerogel fiber is freeze-dried in a freeze-drying machine for 20 to 25 hours to maintain the internal structure of the polyurethane aerogel fiber.

In a further improvement of the present invention, in step S2, the alcohol solution is a mixed solution of water and isopropanol in a volume ratio of (2-4): 1.

As a further improvement of the invention, in step S4, the coagulation bath used in the wet spinning is an aqueous solution, the push injection speed is 8-12 mL/min, and the winding speed is 1500-3500 r/min.

As a further improvement of the present invention, in step S4, the polymer nanofiber powder is mixed with the polyurethane solution by ultrasonic mixing for 10-20 min, so that the polymer nanofiber powder is uniformly dispersed in the polyurethane solution.

As a further improvement of the present invention, in step S1, the organic solvent is one or more of dimethylformamide, dimethylacetamide, tetrahydrofuran, and dimethylsulfoxide; the stirring mode is mechanical stirring at the temperature of 50-70 ℃.

As a further improvement of the invention, the diameter of the polyurethane aerogel fiber is 200-800 μm, and the linear density is 10-25 tex.

The invention has the beneficial effects that:

1. the invention provides a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers, which is based on a wet spinning technology, utilizes the polymer nanofibers to regulate and control the solidification and forming process of the fibers in the wet spinning process by adopting a continuous preparation process, and prepares the ultra-light, high-elasticity and porous polyurethane aerogel fibers. The preparation method is simple and easy to realize, easy to regulate and control, low in cost, green and environment-friendly, and convenient for industrial production; and the prepared product has good performance, can be applied to the aspect of personal heat management materials, and plays an important role in reducing energy waste.

2. According to the polyurethane aerogel fiber added with the polymer nanofibers, a uniform and compact porous structure is formed inside the polyurethane aerogel fiber by controlling the mass ratio of the polymer nanofibers to polyurethane in a polyurethane solution, the specific surface area inside the polyurethane fiber is increased, the structure can realize that air is reserved in a cavity inside the fiber, the static air content is large, the ventilation capacity is small due to the uniform and compact structure, the exchange with outside air is not facilitated, the heat retention property is good, the manufactured textile has a better heat retention effect, and the polyurethane aerogel fiber is better applied to the aspect of personal heat management. Because the internal porous structure and the specific surface area of the prepared polyurethane aerogel nanofiber are increased, the fiber has light weight, and potential application of the fiber as a clothing article is provided for comfort and lightness.

3. The organic solvent is used as a dispersing environment of polyurethane, so that the polyurethane can be efficiently and quickly dissolved, and the concentration of the polymer nano-fiber can be regulated and controlled, so that the porosity, linear density and elastic property of the fiber can be further regulated and controlled. When the polyurethane solution is solidified in the coagulating bath, the organic solvent and water are subjected to solvent exchange, which is favorable for forming a porous structure by the polyurethane aerogel fiber. In addition, the water used as the coagulating bath has the characteristics of safety, environmental protection and reliability.

Drawings

Fig. 1 is a cross-sectional electron microscope image of the polyurethane aerogel fiber added with polymer nanofibers prepared in example 1.

FIG. 2 is a cross-sectional electron micrograph of a polyurethane fiber prepared according to a comparative example.

FIG. 3 is a surface electron microscope image of polyurethane fibers prepared in example 1 and comparative example, (A) is a polyurethane fiber prepared in comparative example, and (B) is a polyurethane aerogel fiber added with polymer nanofibers prepared in example 1.

Fig. 4 is a cross-sectional electron microscope image of the polyurethane aerogel fiber added with polymer nanofibers prepared in example 2.

FIG. 5 is a cross-sectional electron microscope image of the polyurethane aerogel fiber with polymer nanofibers added prepared in example 3.

Fig. 6 is a cross-sectional electron microscope image of the polyurethane aerogel fiber added with polymer nanofibers prepared in example 4.

FIG. 7 is a cross-sectional electron microscope image of the polyurethane aerogel fibers with added polymer nanofibers prepared in example 5.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the aspects of the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.

In addition, it is also to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

A method for constructing ultralight polyurethane aerogel fibers by using polymer nanofibers comprises the following steps:

s1, adding polyurethane into an organic solvent, and mechanically stirring the mixture at the temperature of 50-70 ℃ until the polyurethane is completely dissolved to obtain a polyurethane solution;

the mass fraction of polyurethane in the polyurethane solution is 5-25%, and the polyurethane aerogel elastic fibers with different porosities, linear densities and elastic properties can be obtained by changing the dissolving concentration of the polyurethane. The organic solvent is one or more of dimethylformamide, dimethylacetamide, tetrahydrofuran and dimethyl sulfoxide; the organic solvent is used as a main dispersion environment, so that the polyurethane can be efficiently and quickly dissolved, and the concentration of the polymer nano fibers can be regulated, so that the structural characteristics of the polyurethane aerogel fibers and the like can be further regulated.

S2, adding the polymer nanofiber into an alcohol solution for dispersion, and shearing by using a high-speed beater at the shearing speed of 12000-17000 r/min for 10-15 min to obtain a polymer nanofiber suspension;

the polymer nanofiber is one or more of polyolefin, polyester, polyamide, polyvinyl alcohol or copolymer nanofiber, the diameter of the polymer nanofiber is 50-1000 nm, the length-diameter ratio is not less than 150, and composite fiber with the diameter of 350nm and the length-diameter ratio of 200 is preferred. The alcohol solution is a mixed solution consisting of water and isopropanol in a volume ratio of (2-4): 1.

S3, centrifuging and drying the polymer nanofiber suspension obtained in the step S2 at the centrifuging speed of 10000-150000 r/min to obtain polymer nanofiber powder;

s4, fully mixing the polymer nanofiber powder obtained in the step S3 and the polyurethane solution obtained in the step S1 by adopting ultrasound for 10-20 min, soaking in the aqueous solution for 20-25 h after wet spinning, and freezing and drying to obtain the polyurethane aerogel fiber.

Wherein the mass ratio of the polymer nanofiber powder to the polyurethane is 1 (1-5); the freeze drying treatment is to freeze for 6-8 hours at the temperature of-20-40 ℃, and then the polyurethane aerogel fiber is freeze-dried for 20-25 hours in a freeze dryer to keep the internal structure of the polyurethane aerogel fiber. The polymer nano-fibers are uniformly dispersed in the polyurethane solution before wet spinning, which is beneficial to regulating and controlling the aerogel fibers to form a uniform and compact porous structure, thereby further influencing the characteristics of the aerogel fabric. The push injection speed used in wet spinning is 8-12 mL/min, the winding speed is 1500-3500 r/min, and the size of the fiber diameter can be regulated and controlled by changing the fiber winding speed. The coagulating bath used in the wet spinning is an aqueous solution, and the soaking time is 20-25 h. When the polyurethane solution is solidified in the coagulating bath, the organic solvent and water are subjected to solvent exchange, so that the polyurethane aerogel fibers can form a compact and uniform porous structure. And (3) continuously soaking the polyurethane fiber in water for 20-25 h after wet spinning is finished, so that the exchange of the solvent is more thorough, and the formation of a fiber structure is ensured. In addition, the water used as the coagulating bath has the characteristics of safety, environmental protection and reliability.

The preparation method has a continuous spinning process, is simple and easy to realize, is easy to regulate and control, has low cost, is green and environment-friendly, and is convenient for industrial production; and the prepared product has good performance, can be applied to the aspect of personal heat management materials, and plays an important role in reducing energy waste.

Particularly, the polyurethane aerogel fiber added with the polymer nanofiber is prepared, so that the specific surface area inside the polyurethane fiber is increased, a uniform and compact porous structure is formed inside the polyurethane aerogel fiber, the structure is utilized to realize that an internal cavity retains air, so that the static air content of the polyurethane aerogel fiber is large, the ventilation capacity of the polyurethane aerogel fiber is small due to the uniform and compact structure, the polyurethane aerogel fiber is not beneficial to exchange with external air, the heat retention property is good, the prepared textile has a better heat retention effect, and the polyurethane aerogel fiber can be better applied to the aspect of personal heat management. And the prepared polyurethane aerogel nanofiber has light weight due to the internal porous structure and the increase of the specific surface area, so that the potential application of the polyurethane aerogel nanofiber in the comfort and lightness of clothing articles is provided.

Example 1

The embodiment provides a method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers, and the method for preparing the polyurethane aerogel fibers with the diameters of 400 +/-20 microns comprises the following steps:

(1) weighing 5g of polyurethane slices, adding the polyurethane slices into 100mL of dimethylacetamide, heating to 60 ℃, and mechanically stirring until the high polymer is completely dissolved to obtain a polyurethane solution with the mass fraction of 5%;

(2) adding polyvinyl alcohol-ethylene copolymer nano-fibers into an alcohol solution for dispersion, and shearing by using a high-speed beater at the shearing speed of 15000r/min for 10min to obtain a polymer nano-fiber suspension;

(3) centrifuging and drying the polyvinyl alcohol-ethylene copolymer nanofiber suspension obtained in the step (2), wherein the centrifuging speed is 10000r/min, and obtaining polymer nanofiber powder with the fiber diameter of 300nm and the length-diameter ratio of 180;

(4) adding 5g of the polyvinyl alcohol-ethylene copolymer nanofiber powder obtained in the step (3) into the polyurethane solution obtained in the step (1), fully mixing for 15min by adopting ultrasound, then adopting wet spinning, wherein a coagulating bath is water, the injection speed is 10mL/min, and the winding speed is 1500 r/min; soaking the spun fiber in water solution for 24h, freezing at-30 deg.C for 8h, and freeze-drying in a freeze-drying machine for 22h to obtain the ultra-light, high-elastic and porous polyurethane aerogel fiber with the fiber diameter of 400 + -20 μm.

Comparative example

Comparative example provides a method of preparing a polyurethane fiber having a diameter of 400 ± 20 μm, comprising the steps of:

(1) weighing 5g of polyurethane slices, adding the polyurethane slices into 100mL of dimethylacetamide, heating to 60 ℃, and mechanically stirring until the high polymer is completely dissolved to obtain a polyurethane solution with the mass fraction of 5%;

(2) and (2) performing wet spinning on the polyurethane solution obtained in the step (1), wherein the injection speed is 10mL/min, the winding speed is 1500r/min, soaking in an aqueous solution for 24h, freezing the spun polyurethane fiber at-30 ℃ for 8h, and then freeze-drying in a freeze-drying machine for 22h to obtain the polyurethane aerogel fiber, wherein the fiber diameter of the polyurethane aerogel fiber is 400 +/-20 microns.

Referring to fig. 1 and 2, fig. 1 is a cross-sectional electron microscope image of a polyurethane aerogel fiber with polymer nanofibers added prepared in example 1, and fig. 2 is a cross-sectional electron microscope image of a polyurethane fiber prepared in a comparative example. As can be seen from the figure, the polyurethane aerogel fiber of the embodiment 1 has a uniform and compact porous structure inside, small ventilation capacity and good heat preservation effect; the polyurethane fiber of the comparative example has a loose macroporous structure or a flaky structure inside, the connectivity of the macroporous structure is also high, and the heat retention property is poor. The polyurethane aerogel fiber added with the polymer nanofiber forms a uniform and compact porous structure inside the polyurethane aerogel fiber, so that the specific surface area inside the polyurethane fiber is increased, the static air content of the polyurethane fiber is large, the ventilation capacity of the polyurethane fiber is small due to the uniform and compact structure, the polyurethane aerogel fiber is not beneficial to exchange with external air, and the heat retention property is good; and the prepared polyurethane aerogel nano-fiber has light weight due to the internal porous structure and the increase of the specific surface area.

Referring to fig. 3, fig. 3 is a surface electron microscope image of polyurethane fibers prepared in example 1 and comparative example, wherein fig. (a) is a polyurethane fiber prepared in comparative example, and fig. (B) is a polyurethane aerogel fiber with polymer nanofibers added prepared in example 1. It can be seen from fig. 3 that whether the polymer nano-fiber is added or not has no obvious influence on the appearance of the surface of the polyurethane fiber, and the fiber surfaces of the example 1 and the comparative example still maintain a smooth and flat structure.

Examples 2 to 5

In the method for constructing ultra-light polyurethane aerogel fibers by using polymer nanofibers provided in examples 2 to 5, compared with example 1, the concentration of the polyurethane solution prepared in step (1) is different, the mass fractions of the polyurethane in the polyurethane solution in examples 2 to 5 are 10%, 15%, 20% and 25%, respectively, and the others are substantially the same as those in example 1, and thus, the description is omitted.

Please refer to fig. 4-7, which are cross-sectional electron microscope images of the polyurethane aerogel fibers with polymer nanofibers prepared in examples 2-5. As can be seen from the figure, when the mass fraction of polyurethane in the polyurethane solution is 10%, that is, the mass ratio of the polymer nanofiber powder to the polyurethane is 1:2, the internal structure of the prepared polyurethane aerogel fiber is most uniform and compact, and the number of micropores is large; as the mass fraction of polyurethane in the polyurethane solution continues to increase, segregation of polymer nanofiber powder occurs inside the polyurethane aerogel fibers, and the internal structure is also deteriorated. The method can be used for preparing the polyurethane aerogel fiber with the most uniform and compact structure when the mass ratio of the polymer nanofiber powder to the polyurethane is 1: 2.

The polyurethane aerogel fibers added with polymer nanofibers prepared in examples 1-5 were tested for linear density and elongation at break, and the test results are shown in the following table.

TABLE 1 test results of examples 1-5 and comparative examples

As can be seen from Table 1, in examples 1-5, the linear density of the prepared polyurethane aerogel fibers gradually increased with the increase of the mass fraction of polyurethane; at a polyurethane mass fraction of 10%, i.e. a polymer nanofiber to polyurethane mass ratio of 1:2, elongation at break reached 253%, and elasticity was best, with the elongation at break gradually decreasing as the polyurethane mass fraction continued to increase, indicating a deterioration in elasticity. As can be seen from example 1 and comparative example, the addition of the polymer nanofibers has little effect on the number of pores, and the nanofiber powder has a great effect on the size and uniformity of the pore structure of the polyurethane aerogel fibers as can be seen from the electron microscope images. In conclusion, on the premise of ensuring the elasticity and the heat retention of the prepared polyurethane aerogel fiber, the mass fraction of polyurethane is not too large, and when the mass fraction of polyurethane is 10%, the internal structure of the fiber is the most uniform and compact, the linear density is smaller, and the elasticity is the best.

Example 6

The embodiment provides a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers, and the method is used for preparing the polyurethane aerogel fibers with the diameters of 350 +/-20 microns; compared with the example 1, the winding speed in the wet spinning in the step (4) is 2500r/min, and the rest is substantially the same as the example 1, and the description is omitted.

Example 7

The embodiment provides a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers, and the method is used for preparing the polyurethane aerogel fibers with the diameters of 300 +/-20 microns; compared with example 1, the winding speed in the wet spinning in step (4) is 3500r/min, and the rest is substantially the same as example 1, and will not be described again.

Example 8

The embodiment provides a method for constructing ultra-light polyurethane aerogel fibers by polymer nanofibers, and the method is used for preparing the polyurethane aerogel fibers with the diameters of 100 +/-20 microns; compared with the example 1, the winding speed in the wet spinning in the step (4) is 5000r/min, and the rest is substantially the same as the example 1, and the description is omitted.

Table 2 examples 6-8 test results

Examples	Winding speed (r/min)	Fiber diameter (μm)	Linear Density (tex)	Elongation at Break (%)
					Example 1	1500	400	14.7	240
Example 6	2500	350	14.2	215
					Example 7	3500	300	13.4	186
Example 8	5000	100	8.6	125

As can be seen from Table 2, in examples 6 to 8, as the winding speed in wet spinning increases, the diameter and linear density of the prepared polyurethane aerogel fiber become smaller and the elongation at break also decreases, indicating that the elasticity of the fiber becomes poor. At a winding speed of 5000r/min in example 8, the diameter of the fiber was 100, and the elongation at break was only 125%, at which time the elasticity of the fiber was the worst as compared with the other examples; therefore, the winding speed of the polyurethane aerogel fiber prepared by the method is not suitable to be too high during wet spinning.

In summary, the invention provides a method for constructing an ultra-light polyurethane aerogel fiber by using polymer nanofibers, which comprises the steps of adding the polymer nanofibers into a polyurethane solution, and regulating and controlling a fiber solidification forming process in a wet spinning process to obtain the ultra-light, high-elasticity and porous polyurethane aerogel fiber. According to the method, the polymer nano fibers are added, a uniform and compact porous structure is formed in the polyurethane aerogel fibers, the specific surface area in the polyurethane fibers is improved, the structure can realize that air is reserved in an internal cavity, the static air content is large, the ventilation capacity is small due to the uniform and compact structure, the exchange with the external air is not facilitated, the heat retention property is good, the manufactured textile has a better heat retention effect, and the method is better applied to the aspect of personal heat management. The prepared polyurethane aerogel nanofiber has a light weight due to the internal porous structure and the increase of the specific surface area, and potential application of the polyurethane aerogel nanofiber in comfort, lightness and thinness as clothing articles is provided. The method has a continuous spinning process, is simple and easy to realize, easy to regulate and control, low in cost, green and environment-friendly, and convenient for industrial production; and the prepared product has good performance, can be applied to the aspect of personal heat management materials, and plays an important role in reducing energy waste.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.