CN110396771B

CN110396771B - Preparation method of nanofiber non-woven fabric

Info

Publication number: CN110396771B
Application number: CN201910606609.6A
Authority: CN
Inventors: 郭启浩; 刘轲; 王栋; 王旭; 赵青华
Original assignee: Foshan We Change Technology Co ltd; Wuhan Textile University
Current assignee: Foshan We Change Technology Co ltd; Wuhan Textile University
Priority date: 2019-07-05
Filing date: 2019-07-05
Publication date: 2020-09-01
Anticipated expiration: 2039-07-05
Also published as: CN110396771A

Abstract

The invention discloses a preparation method of a nanofiber non-woven fabric, which comprises the steps of melting and blending thermoplastic polymers which are not compatible with thermodynamics and a matrix according to a certain mass ratio, carrying out melt extrusion and melt blowing to obtain composite fibers, depositing single-layer composite fibers on a receiving device, obtaining a single-layer composite fiber net through self adhesion, dissolving and removing the matrix in the composite fiber net by adopting a solvent to obtain a nanofiber net containing a thermoplastic polymer phase, sequentially collecting a second layer, a third layer, … and an n-th layer of polymer nanofiber net on the single-layer nanofiber non-woven fabric by adopting the same method, and finally carrying out hot rolling reinforcement treatment to obtain the nanofiber non-woven fabric. The invention can prepare the nanofiber non-woven fabric with the nanofiber diameter of less than 200nm and the thickness of 0.2-5 mu m, and has the advantages of high uniformity and strength of the fiber diameter, simple preparation method, low cost and large-scale preparation.

Description

Preparation method of nanofiber non-woven fabric

Technical Field

The invention belongs to the technical field of textile material preparation, and particularly relates to a preparation method of a nanofiber non-woven fabric.

Background

In the development of fiber science and engineering, fiber ultra-fining is an important direction, and the nano fiber is a linear material with a diameter of nano scale and a large length and a certain length-diameter ratio, has a very obvious size effect, shows a plurality of novel characteristics in the aspects of light, heat, magnetism, electricity and the like, further endows woven cloth or non-woven cloth made of the nano fiber with special properties, and has great application value in the fields of clothing, food, medicine, energy, electronics, aviation and the like. However, the so-called nanofibers are broadly defined nanofibers, i.e., fibers having a fiber diameter of less than 1 μm, and there is a difficulty in mass production of fibers having a diameter of less than 200 nm. The preparation technology of the existing nano-fiber mainly comprises a template synthesis method, a phase separation method, a self-assembly method, a drawing method, an electrostatic spinning method and the like.

The preparation method of the nanofiber comprises the steps of mixing and spinning two thermodynamically incompatible polymers to obtain composite fibers, and dissolving matrix components with a proper solvent to obtain the nanofiber of a target polymer. The method is suitable for producing thermoplastic polymer nanofibers. For example, chinese patent application No. 201710282915.X discloses a nanofiber production process, in which a thermodynamically incompatible polymer and a matrix are dissolved with a solvent to prepare an electrospinning solution, and then electrospinning is performed to obtain a composite fiber, and the matrix is dissolved and removed by dissolution to obtain a polymer nanofiber having an average diameter of less than 100 nm. The method adopts solution electrostatic spinning, so that the problems of difficult solvent selection, environmental pollution and high cost exist, and the solution method is difficult to control two groups of polymers to be independently stretched into filaments, so that two polymers are contained in a single nanofiber precursor, and after one phase of the two polymers is dissolved and removed, the nanofiber precursor is broken, so that the strength of the nanofiber is reduced.

Therefore, in order to solve the problems, the invention adopts a melt extrusion phase separation method to prepare the nanofiber cloth, and simultaneously carries out technical improvement aiming at the problems that when the thickness of the nanofiber non-woven fabric is thicker, the polymer to be separated from the inner layer is difficult to dissolve and remove, so that the diameter distribution of the nanofiber non-woven fabric is uneven, and the performance is not uniform.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a preparation method of a nanofiber non-woven fabric, which is characterized in that a melt extrusion phase separation method is adopted to prepare nanofibers, and the nanofibers are collected in a layered mode to form a net and are subjected to hot rolling treatment to obtain the nanofiber non-woven fabric with the diameter of less than 200nm, the thickness of the nanofiber non-woven fabric prepared by the method can be accurately controlled, and the nanofiber non-woven fabric with the thickness of 0.2-5 mu m can be prepared.

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

a preparation method of nanofiber non-woven fabric is characterized in that thermoplastic polymer and matrix which are not compatible with each other in thermodynamics are melted and blended according to a certain mass ratio, composite fibers are obtained through melt extrusion and melt blowing, the composite fibers are deposited on a receiving device, and a composite fiber net is obtained through self-adhesion;

dissolving and removing the matrix in the composite fiber web by using a solvent to obtain a polymer-containing nanofiber web, and reinforcing by adopting hot rolling treatment to obtain the polymer-containing nanofiber non-woven fabric.

Further, when the number of the composite fiber layers deposited in the composite fiber web is multiple, firstly collecting to obtain a single-layer composite fiber web, and dissolving and removing the matrix by using a solvent to obtain a single-layer polymer nanofiber web; and then collecting a second layer, a third layer, …, and an nth layer of polymer nanofiber web on the single-layer nanofiber non-woven fabric in sequence by the same method, and finally obtaining the nanofiber non-woven fabric containing the polymer through hot rolling reinforcement treatment.

Furthermore, the diameter of the polymer nanofiber in the nanofiber non-woven fabric is less than or equal to 200 nm.

Further, the mass ratio of the polymer to the matrix is 1: 9-1: 2.

Further, the thermoplastic polymer is any one or more of polyvinyl alcohol, polyvinyl butyral, polypropylene, polyethylene, polyamide or thermoplastic polyurethane.

Further, the substrate is any one of cellulose acetate, ethyl cellulose, or cellulose acetate butyrate.

Further, the solvent is acetone or ethanol.

Further, the melt blending is carried out by adopting a double-screw extruder, and parameters of each zone of the double-screw extruder are set as follows: temperature in the first zone: 130-180 ℃; temperature in the second zone: 190-210 ℃; three-zone temperature: 210-230 ℃; temperature in the fourth zone: 215-235 ℃; temperature in the fifth zone: 215 to 250 ℃.

Further, the melt-blowing adopts high-temperature high-pressure air flow for blowing, the temperature of the high-temperature high-pressure air flow is 260-280 ℃, and the pressure is 0.15-0.25 MPa; the receiving device is a web former.

Furthermore, a double-roller hot rolling mill is adopted in the hot rolling treatment, the hot rolling temperature is 140-180 ℃, the pressure is 5-20 MPa, and the hot rolling time is 5-20 s.

Advantageous effects

Compared with the prior art, the preparation method of the nanofiber non-woven fabric provided by the invention has the following beneficial effects:

(1) the invention adopts a melt extrusion phase separation method to prepare the nano-fiber, and obtains the nano-fiber non-woven fabric with the diameter less than 200nm through layered collection, web formation and hot rolling treatment, the thickness of the nano-fiber non-woven fabric prepared by the method can reach the accurate control of the nanometer level, and the nano-fiber non-woven fabric with the thickness as low as 0.2-5 mu m can be prepared.

(2) The invention adopts a melt phase separation method, does not need to use a solvent, reduces the production cost and has no pollution to the environment; in addition, a melt phase separation method is adopted, so that the protofilaments of the two components can be radially separated in the process of drawing to form filaments, and when the matrix is dissolved and removed, the radial composition of the nano fibers is unchanged, the nano fibers cannot be broken, and the fiber stability is improved.

(3) According to the invention, through reasonably setting parameters of melt extrusion, melt blowing and hot rolling, the prepared nanofiber cloth has the advantages of high diameter uniformity of nanofibers, high performance stability, strong binding power and relatively high tensile strength.

Drawings

FIG. 1 is a flow chart of a process for preparing a nanofiber nonwoven fabric;

FIG. 2 is a schematic diagram of the principle of preparing nanofiber cloth by melt extrusion phase separation;

FIG. 3 is a scanning electron microscope image of the nanofiber nonwoven fabric prepared in example 1.

Detailed Description

The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

As shown in fig. 1, a preparation process flow chart of the invention is that two groups of thermoplastic polymers and matrixes which are not compatible with each other thermodynamically are selected to be melted and blended in a double screw extruder and then extruded from a spinneret orifice, high-temperature and high-pressure airflow is adopted for melt-blowing to obtain a stretched composite fiber filament, after solidification and deposition in cold air, a composite fiber web is obtained through self-bonding, then a solvent capable of dissolving the matrix is used for dissolving and removing the matrixes in the composite fiber web to obtain a nanofiber web containing the thermoplastic polymers, then a second layer, a third layer, … and an n layer of polymer nanofiber web are sequentially collected on a single-layer nanofiber non-woven fabric by the same method, and finally the nanofiber non-woven fabric containing the polymers is obtained through hot rolling and reinforcement.

In order to obtain the superfine nano-fiber after dissolving and removing the matrix, the mass ratio of the polymer to the matrix is 1: 9-1: 2, preferably 1: 9-1: 4, the aim is to enable the content of the matrix to be far larger than that of the polymer, so that a mixture similar to a 'sea-island' structure is formed, and the formation of separate fiber filaments in the melt-blown filamentation process is facilitated.

The matrix is any one of cellulose acetate, ethyl cellulose or cellulose acetate butyrate, preferably Cellulose Acetate Butyrate (CAB), and the CAB has good film forming property, can be dissolved in solvents such as acetone and the like, is helpful for forming a web of fibers, and is easy to dissolve and remove.

The thermoplastic polymer is any one or more of polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polypropylene (PP), Polyethylene (PE), polyamide or thermoplastic polyurethane, preferably one or more of polyvinyl alcohol, polyvinyl butyral, polypropylene and polyamide.

The parameters of each zone of the double-screw extruder are set as follows: temperature in the first zone: 130-180 ℃; temperature in the second zone: 190-210 ℃; three-zone temperature: 210-230 ℃; temperature in the fourth zone: 215-235 ℃; temperature in the fifth zone: 215 to 250 ℃.

Specifically, the appropriate temperature of each zone is set according to the melting temperature and the melt index of the thermoplastic polymer, and when the thermoplastic polymer is polypropylene, the parameters of each zone of the twin-screw extruder are preferably set as follows: temperature in the first zone: 130 ℃; temperature in the second zone: 190 ℃; three-zone temperature: at 210 ℃; temperature in the fourth zone: 220 ℃; temperature in the fifth zone: 230 ℃ to 230 ℃.

The schematic diagram of the invention for preparing the nanofiber non-woven fabric is shown in figure 2, because the thermoplastic polymer and the matrix are two components which are thermodynamically incompatible, two disperse phases in figure 2 are formed in a melt blending body, when the content of the matrix is far larger than that of the thermoplastic polymer, the thermoplastic polymer is uniformly dispersed in the matrix to form a melt blending body similar to a sea-island structure, when the melt blending body is sprayed out from a spinneret orifice, composite fiber filaments are gradually formed under the action of high-temperature and high-pressure air flow melt-blowing, the composition of the composite fiber filaments is shown in figure 2, because the polymer and the matrix are thermodynamically incompatible, the polymer independently forms the nanofiber filaments in the melt-blowing filamentation process, the matrix forms a longitudinal continuous phase on an outer layer, because the matrix has better film-forming property, the collection of the matrix into a net is facilitated, and the composite fiber net is obtained through self-, and dissolving the polymer by using a solvent to remove the matrix to obtain a polymer nanofiber web, and performing hot rolling reinforcement by using a double-roller hot rolling mill to obtain a nanofiber non-woven fabric, wherein the prepared nanofiber cloth has the advantages of high diameter uniformity, high performance stability, strong binding power and relatively high tensile strength.

Example 1

A preparation method of nanofiber non-woven fabric is characterized by comprising the following steps:

s1, melting and blending polypropylene (PP) and Cellulose Acetate Butyrate (CAB) in a double-screw extruder according to a mass ratio of 1:9, wherein the parameters of each area of the double-screw extruder are preferably set as follows: temperature in the first zone: 130 ℃; temperature in the second zone: 190 ℃; three-zone temperature: at 210 ℃; temperature in the fourth zone: 220 ℃; temperature in the fifth zone: 230 ℃;

s2, filtering the molten fluid, feeding the filtered fluid into a spinning box, and extruding the fluid into filaments through a spinneret plate;

s3, carrying out melt blowing by adopting high-temperature and high-pressure airflow with the temperature of 260-280 ℃ and the pressure of 0.15-0.25 MPa, stretching a melt into superfine fibers under the action of high-speed hot airflow, solidifying the superfine fibers into composite fiber filaments through heat exchange with surrounding cold air, collecting a web by adopting a web former to obtain a composite fiber web, and controlling the thickness of the composite fiber web by controlling the spinning speed and the web forming time;

s4, immersing the composite fiber net into acetone, performing ultrasonic extraction in the acetone, and removing CAB to obtain a polypropylene nano fiber net;

and S5, carrying out hot rolling reinforcement on the polypropylene nanofiber net by using a double-roller hot rolling mill to obtain the polypropylene nanofiber non-woven fabric, wherein the hot rolling temperature is 140-160 ℃, the pressure is 5-12 MPa, and the hot rolling time is 5-10 s.

Example 2

Embodiment 2 provides a method for preparing a nanofiber nonwoven fabric, including the steps of:

s4, immersing the composite fiber net into acetone, performing ultrasonic extraction in the acetone, and removing the matrix CAB to obtain a polypropylene nano fiber net;

s5, taking the polypropylene nano-fiber net obtained in the step S4 as a template, continuously depositing composite fibers on the surface of the polypropylene nano-fiber net, repeating the steps S3 and S4, and sequentially collecting the polypropylene nano-fiber nets of the 3 rd layer and the 4 th layer by adopting the same method;

and S6, carrying out hot rolling reinforcement on the polypropylene nanofiber net by using a double-roller hot rolling mill to obtain the polypropylene nanofiber non-woven fabric, wherein the hot rolling temperature is 140-160 ℃, the pressure is 5-12 MPa, and the hot rolling time is 5-10 s.

Examples 3 to 8

Examples 3 to 8 are different from example 1 in that the preparation conditions of the polypropylene nanofiber nonwoven fabric are as shown in table 1, and the other conditions are the same as those of example 1.

TABLE 1 preparation conditions of examples 3-8 nanofiber nonwoven fabrics

The average diameter of the polypropylene nanofiber nonwoven fabric fibers and the thickness of the nonwoven fabric prepared in examples 1 to 8 are shown in table 2, and it can be seen that the average diameter of the polypropylene nanofiber and the thickness of the single-layer nonwoven fabric are gradually increased with the increase of the mass ratio of polypropylene (PP) to Cellulose Acetate Butyrate (CAB), which indicates that the appropriate increase of CAB content is helpful for reducing the diameter of the nanofiber. The reason is that when the CAB content is increased, the CAB in the spinning trickle can more effectively prevent the PP molten phase from being enlarged, the PP phase is stretched and refined under the melt-blown action with smaller grain diameter, and the polypropylene nano-fiber net is obtained after the CAB is dissolved. The nanofiber nonwoven fabric prepared in example 1 was a single layer having a thickness as low as 0.21 μm, and as can be seen from fig. 3, the nanofiber nonwoven fabric prepared in example 1 had a uniform distribution of diameters of polypropylene nanofibers. Example 2 the thickness of the four-layer non-woven fabric prepared by multilayer deposition is 0.85 μm, which shows that the thickness of the non-woven fabric is increased with the increase of the number of the deposited layers of the polypropylene fiber, namely the thickness of the non-woven fabric can be regulated in a nanometer scale.

TABLE 2 average diameter and thickness of polypropylene nanofiber nonwoven prepared in examples 1 to 8

Examples 9 to 14

Examples 9 to 14 are different from example 1 in that the blend composition, the kind of solvent and the melt extrusion parameters are shown in table 3, and the other examples are the same as example 1.

TABLE 3 examples 9-14 blend compositions, solvent types, and melt extrusion parameters

The average fiber diameter and the thickness of the polypropylene nanofiber nonwoven prepared in examples 9 to 14 are shown in table 4, and it can be seen that the nanofiber nonwoven with the average fiber diameter of less than 200nm and the thickness as low as 0.22 to 0.24 μm can be obtained for different thermodynamically incompatible polymers and matrixes by using the preparation method of the nanofiber nonwoven provided by the invention.

TABLE 4 average diameter and thickness of polypropylene nanofiber nonwoven prepared in examples 9-14

Examples	Average diameter of composite fiber (nm)	Average diameter (nm) of polypropylene nanofibers	Thickness of non-woven fabric (mum)
				9	482	60	0.22
10	485	63	0.22
				11	500	68	0.23
12	493	65	0.22
				13	505	73	0.24
14	485	63	0.23

Examples 15 to 18

Examples 15 to 18 differ from example 1 in that the polymer is a multicomponent polymer, the composite nanofiber nonwoven fabric is prepared, the matrix is preferably cellulose acetate butyrate, the solvent is preferably acetone, the polymer composition and melt extrusion parameters are shown in table 5, and the other steps are the same as those in example 1.

TABLE 5 examples 15-18 Polymer compositions and melt extrusion parameters

The average fiber diameter and the thickness of the polypropylene nanofiber nonwoven prepared in examples 15 to 18 are shown in table 6, and it can be seen that the nanofiber nonwoven provided by the invention is also suitable for multi-component polymers, and nanofiber nonwoven with the average fiber diameter of less than 200nm and the thickness of 0.22 to 0.25 μm can be obtained, so that the nonwoven has various properties.

TABLE 6 average diameter and thickness of polypropylene nanofiber nonwoven prepared in examples 15 to 18

Examples	Average diameter of composite fiber (nm)	Average diameter (nm) of polypropylene nanofibers	Thickness of non-woven fabric (mum)
				15	496	72	0.24
16	485	66	0.22
				17	500	76	0.25
18	493	69	0.23

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A preparation method of nanofiber non-woven fabric is characterized in that thermoplastic polymer and matrix which are not compatible with each other in thermodynamics are melted and blended according to a certain mass ratio, composite fibers are obtained through melt extrusion and melt blowing, the composite fibers are deposited on a receiving device, and a composite fiber net is obtained through self-adhesion;

dissolving and removing a matrix in the composite fiber web by using a solvent to obtain a polymer-containing nanofiber web, and reinforcing by adopting hot rolling treatment to obtain a polymer-containing nanofiber non-woven fabric;

when the number of the composite fiber layers deposited in the composite fiber net is multiple, firstly collecting to obtain a single-layer composite fiber net, and dissolving and removing the matrix by adopting a solvent to obtain a single-layer polymer nano fiber net; then sequentially collecting a second layer, a third layer, … and an nth layer of polymer nanofiber web on the single-layer nanofiber non-woven fabric by the same method, and finally obtaining the nanofiber non-woven fabric containing the polymer through hot rolling reinforcement treatment;

the mass ratio of the polymer to the matrix is 1: 9-1: 2;

the melt-blowing adopts high-temperature high-pressure air flow for blowing, the temperature of the high-temperature high-pressure air flow is 260-280 ℃, and the pressure is 0.15-0.25 MPa; the receiving device is a web former;

the hot rolling treatment adopts a double-roller hot rolling mill, the hot rolling temperature is 140-180 ℃, the pressure is 5-20 MPa, and the hot rolling time is 5-20 s.

2. The method of claim 1, wherein the diameter of the polymer nanofibers in the nanofiber nonwoven is less than or equal to 200 nm.

3. The method of claim 1, wherein the thermoplastic polymer is one or more of polyvinyl alcohol, polyvinyl butyral, polypropylene, polyethylene, polyamide, or thermoplastic polyurethane.

4. The method of claim 1, wherein the substrate is any one of cellulose acetate, ethyl cellulose, or cellulose acetate butyrate.

5. The method of claim 1, wherein the solvent is acetone or ethanol.

6. The method for preparing the nanofiber non-woven fabric as claimed in claim 1, wherein the melt blending is performed by using a twin-screw extruder, and parameters of each zone of the twin-screw extruder are set as follows: temperature in the first zone: 130-180 ℃; temperature in the second zone: 190-210 ℃; three-zone temperature: 210-230 ℃; temperature in the fourth zone: 215-235 ℃; temperature in the fifth zone: 215 to 250 ℃.