阅读说明：本技术 芳纶纳米纤维及其制备方法和应用、芳纶纸的制备方法 (Aramid nanofiber, preparation method and application thereof, and preparation method of aramid paper ) 是由 李永锋 常小斌 李金鹏 王斌 陈克复 曾劲松 蒋少波 李建雄 于 2021-09-16 设计创作，主要内容包括：本发明提供了一种芳纶纳米纤维及其制备方法和应用、芳纶纸的制备方法,该芳纶纳米纤维的制备方法包括以下步骤：将芳纶聚合物分散至第一溶剂中得到芳纶聚合物分散液；经气喷雾化处理后喷射于第二溶剂中,得到分散液；再将经过超微粒磨浆处理。本发明的制备方法,利用高速流动的压缩气体将芳纶聚合物分散液打乱和分散,得到芳纶微纳米纤维分散液,通过调节芳纶聚合物分散液的浓度以及压缩气体的工作压力实现芳纶聚合物排列结构调控,雾化的微纳级芳纶聚合物分子链在湍流区收气流扰动分散,并在气流场作用下拉伸排列,固化后得到芳纶微纳米纤维分散液；再通过进一步的超微粒磨浆处理,从而实现芳纶纤维纵向分离,实现微纳米纤维尺寸的可控可调。(The invention provides aramid nano-fiber, a preparation method and application thereof, and a preparation method of aramid paper, wherein the preparation method of the aramid nano-fiber comprises the following steps: dispersing an aramid polymer into a first solvent to obtain an aramid polymer dispersion liquid; spraying the mixture into a second solvent after gas spray atomization treatment to obtain a dispersion liquid; then the superfine grain pulp is grinded. According to the preparation method, the aramid fiber polymer dispersion liquid is disordered and dispersed by using high-speed flowing compressed gas to obtain the aramid fiber micro-nanofiber dispersion liquid, the aramid fiber polymer arrangement structure is regulated and controlled by adjusting the concentration of the aramid fiber polymer dispersion liquid and the working pressure of the compressed gas, the atomized micro-nano aramid polymer molecular chains are disturbed and dispersed by receiving airflow in a turbulent flow zone and are stretched and arranged under the action of an airflow field, and the aramid fiber micro-nanofiber dispersion liquid is obtained after solidification; and then through further ultramicro-particle pulping treatment, longitudinal separation of aramid fibers is realized, and the size of the micro-nanofibers is controllable and adjustable.)

1. The preparation method of the aramid nanofiber is characterized by comprising the following steps of:

dispersing an aramid polymer into a first solvent to prepare an aramid polymer dispersion liquid;

spraying the aramid polymer dispersion liquid into a second solvent with a curing effect after air-jet atomization treatment to obtain an aramid micro-nanofiber dispersion liquid;

and then carrying out ultramicro-grain grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain the aramid fiber nano fibers.

2. The method for preparing the aramid nanofiber as claimed in claim 1, wherein the first solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and acetone; the second solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, acetone, an aqueous solution of dimethylacetamide, an aqueous solution of dimethylformamide, an aqueous solution of dimethyl sulfoxide and an aqueous solution of acetone.

3. The method for preparing the aramid nanofiber as claimed in claim 1, wherein the aramid polymer comprises one or more of poly (m-phenylene isophthalamide), poly (p-phenylene terephthalamide), and polyamide polymer containing a heterocyclic structure.

4. The preparation method of the aramid nanofiber as claimed in claim 1, wherein the specific process of the air-jet atomization treatment is as follows: the aperture of the atomization hole is 0.1-8.0 mm, and the pressure of compressed gas is 0.1-1.0 MPa.

5. The preparation method of the aramid nanofiber as claimed in claim 1, wherein the preparation of the aramid polymer dispersion liquid by dispersing the aramid polymer into the first solvent is specifically: dispersing the aramid polymer into a first solvent, and stirring for 1-60 min at 50-1000 rpm to obtain an aramid polymer dispersion liquid.

6. The method for preparing the aramid nanofibers according to claim 1, wherein the specific process of the ultra-fine particle grinding treatment is as follows: the gap between the millstones is-100 mu m to 100 mu m, and the grinding times are 1 to 100 times;

the mass concentration of the aramid polymer dispersion liquid is 0.01-20%.

7. The method for preparing the aramid nanofibers according to claim 2, wherein the mass concentrations of the aqueous dimethylacetamide solution, the aqueous dimethylformamide solution, the aqueous dimethylsulfoxide solution and the aqueous acetone solution are all 0-60%.

8. The aramid nanofiber is characterized by being prepared by the preparation method of any one of claims 1-7.

9. Use of the aramid nanofiber as claimed in claim 8 for the preparation of composite reinforcement materials, battery separators, electrically insulating nanopapers, flexible electronic devices, adsorptive filter media.

10. The preparation method of the aramid paper is characterized by comprising the following steps of:

mixing the aramid nanofibers, the aramid chopped fibers and the aramid pulp according to claim 8 to obtain a fiber dispersion liquid;

defibering the fiber dispersion liquid, making sheets by a Kaiser method to prepare base paper, and carrying out hot pressing to obtain the aramid paper.

Technical Field

The invention relates to the technical field of polymer materials, in particular to aramid nano-fibers, a preparation method and application thereof, and a preparation method of aramid paper.

Background

In recent years, high-performance fiber materials have excellent mechanical properties, dielectric strength, chemical and thermal stability, and play an important role in high-tech development fields such as aerospace, transportation, electric power communication, national defense industry and the like, and have become one of the hot spots for new material research in the 21 st century. The nano-scale aramid fiber has the advantages of both high-performance aramid fiber and polymer nanofiber, and can effectively solve the problems of smooth surface and unsatisfactory composite effect of the conventional aramid fiber to a certain extent. However, as an important member of a high-performance aromatic polyester fiber family, the characteristics of high strength, high modulus, high temperature resistance, corrosion resistance and the like of the aramid fiber bring certain difficulties for realizing controllable nano-preparation, which also results in less technologies available for preparing the aramid nanofiber at present.

The currently disclosed preparation methods of the aramid nano-fiber comprise electrostatic spinning, rotary jet spinning, alkali-synergetic mechanical milling and hydrolysis, an alkali dissolution method, a polymerization dispersion method and the like; wherein, the electrostatic spinning method has low production efficiency and difficult size regulation; the alkali fusion method needs to dissolve aramid fiber and then redisperse, and the process is complicated; the mechanical method has high energy consumption and large power consumption; the existing jet spinning technology adopts an inner liquid inlet pipe and an outer air inlet pipe, and the prepared aramid fiber has the advantages of large diameter, uncontrollable length and wide size distribution range.

The technical defects limit the industrialization process and the application range of the aramid nano-fiber. Therefore, there is a need for improvement of the existing methods for preparing aramid nanofibers.

Disclosure of Invention

In view of the above, the invention provides a preparation method of aramid nanofiber, and a preparation method and application thereof, so as to solve or partially solve the technical problems in the prior art.

In a first aspect, the invention provides a preparation method of aramid nano-fiber, which comprises the following steps:

dispersing an aramid polymer into a first solvent to prepare an aramid polymer dispersion liquid;

spraying the aramid polymer dispersion liquid into a second solvent with a curing effect after air-jet atomization treatment to obtain an aramid micro-nanofiber dispersion liquid;

and then carrying out ultramicro-grain grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain the aramid fiber nano fibers.

Preferably, in the preparation method of the aramid nanofiber, the first solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide and acetone; the second solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, acetone, an aqueous solution of dimethylacetamide, an aqueous solution of dimethylformamide, an aqueous solution of dimethyl sulfoxide and an aqueous solution of acetone.

Preferably, the aramid polymer comprises one or more of poly (m-phenylene isophthalamide), poly (p-phenylene terephthalamide) and polyamide polymer containing a heterocyclic ring structure.

Preferably, in the preparation method of the aramid nanofiber, the specific process of the air-jet atomization treatment is as follows: the aperture of the atomization hole is 0.1-8.0 mm, and the pressure of compressed gas is 0.1-1.0 MPa.

Preferably, the preparation method of the aramid nanofiber comprises the following steps of dispersing the aramid polymer into the first solvent to prepare the aramid polymer dispersion liquid: dispersing the aramid polymer into a first solvent, and stirring for 1-60 min at 50-1000 rpm to obtain an aramid polymer dispersion liquid.

Preferably, the preparation method of the aramid nano-fiber comprises the following specific process of superfine particle grinding treatment: the gap between the millstones is-100 mu m to 100 mu m, and the grinding times are 1 to 100 times.

Preferably, in the preparation method of the aramid nanofiber, the mass concentration of the aramid polymer dispersion liquid is 0.01-20%.

Preferably, in the preparation method of the aramid nanofiber, the mass concentrations of the dimethylacetamide aqueous solution, the dimethylformamide aqueous solution, the dimethyl sulfoxide aqueous solution and the acetone aqueous solution are all 0-60%.

In a second aspect, the invention also provides aramid nano-fibers prepared by the preparation method.

In a third aspect, the invention also provides application of the aramid nano-fiber in preparation of composite reinforced materials, battery diaphragms, electric insulation nano-paper, flexible electronic devices and adsorption filter media.

In a third aspect, the invention also provides a preparation method of the aramid paper, which is characterized by comprising the following steps:

mixing the aramid nano-fiber, the aramid chopped fiber and the aramid pulp to obtain a fiber dispersion liquid;

defibering the fiber dispersion liquid, making sheets by a Kaiser method to prepare base paper, and carrying out hot pressing to obtain the aramid paper.

The aramid nanofiber and the preparation method and application thereof in the prior art have the following beneficial effects:

(1) according to the preparation method of the aramid nano-fiber, the aramid polymer dispersion liquid is disordered and dispersed by using high-speed flowing compressed gas, the atomized aramid polymer dispersion liquid is fully mixed with the second solvent with a solidification effect to obtain the aramid micro-nanofiber dispersion liquid, the aramid polymer arrangement structure can be regulated and controlled by adjusting the concentration of the aramid polymer dispersion liquid and the working pressure of the compressed gas, the atomized micro-nano aramid polymer molecular chains are subjected to airflow disturbance and dispersion in a turbulent flow zone and are stretched and arranged under the action of an airflow field, and the aramid micro-nanofiber dispersion liquid is obtained after solidification; then, through further ultramicron pulp grinding treatment, longitudinal separation of aramid fibers is realized, and the size of the micro-nano fibers is controllable and adjustable;

(2) according to the preparation method of the aramid nanofiber, the prepared micro-nanofiber has a unique fibrillating structure and a larger specific surface area, the bonding strength of the fiber interface in the aramid paper can be obviously improved, the mechanical strength and the dielectric property of the aramid paper can be effectively improved, and the method can be widely applied to the field of new high-end insulating materials.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a schematic flow diagram of a preparation method of aramid nanofibers according to the present invention;

FIG. 2 is a surface topography SEM image of the aramid nanofibers prepared in example 4 of the present invention;

fig. 3 is a diameter frequency histogram of the aramid nanofibers prepared in example 4 of the present invention.

Detailed Description

In the following, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is obvious 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 obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The embodiment of the application provides a preparation method of aramid nanofibers, as shown in fig. 1, comprising the following steps:

s1, dispersing the aramid polymer into a first solvent to prepare an aramid polymer dispersion liquid;

s2, spraying the aramid polymer dispersion liquid into a second solvent with a curing effect after air-jet atomization treatment to obtain an aramid micro-nanofiber dispersion liquid;

and S3, carrying out ultramicro-grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain the aramid fiber nano fibers.

The principle of the air-jet atomization treatment in the preparation method of the aramid nanofiber is as follows: by utilizing a compression type atomizer (also called a jet atomizer), according to a Venturi injection principle, high-speed airflow is formed by utilizing compressed gas through a fine pipe orifice, the generated negative pressure drives aramid polymer dispersion liquid to be injected onto an obstacle together, and the aramid polymer dispersion liquid splashes around under high-speed impact to change liquid drops into vaporous particles to be injected out of an atomizing hole; the aramid fiber micro-nano fiber dispersion liquid is disordered and dispersed by using high-speed flowing compressed gas, the atomized aramid fiber polymer dispersion liquid is fully mixed with a second solvent with a solidification effect to obtain the aramid fiber micro-nano fiber dispersion liquid, the aramid fiber polymer arrangement structure can be regulated and controlled by adjusting the concentration of the aramid fiber polymer dispersion liquid and the working pressure of the compressed gas, the atomized micro-nano aramid fiber polymer molecular chains are disturbed and dispersed by airflow in a turbulent flow zone and are stretched and arranged under the action of an airflow field, and the aramid fiber micro-nano fiber dispersion liquid is obtained after solidification; and then, longitudinal separation of aramid fibers is realized through further optimized ultramicron pulp grinding treatment, and the controllability and adjustability of the size of the micro-nano fibers are realized. The micro-nanofiber prepared by the preparation method of the aramid nanofiber has a unique fibrillating structure and a larger specific surface area, can obviously improve the bonding strength of a fiber interface in aramid paper, effectively improves the mechanical strength and the dielectric property of the aramid paper, and can be widely applied to the field of new high-end insulating materials. The preparation method of the aramid nano-fiber is simple in preparation operation, convenient and easy to implement, high in production efficiency compared with the conventional preparation method at present, and suitable for industrial continuous production. The preparation method of the aramid nano-fiber can also add functional groups into the aramid polymer to increase the functionalization and high performance of the aramid polymer, and has important significance for the cross diversified application of the aramid nano-fiber in various fields such as reinforced materials, battery diaphragms, electric insulation nano-paper, flexible electronic devices, adsorption and filtration media and the like.

In some embodiments, the first solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethylsulfoxide, acetone;

the second solvent comprises one or more of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, acetone, an aqueous solution of dimethylacetamide, an aqueous solution of dimethylformamide, an aqueous solution of dimethyl sulfoxide and an aqueous solution of acetone.

In the above embodiments, the second solvent may be other solvents that can be cured with the aramid polymer dispersion liquid, besides dimethylacetamide, dimethylformamide, dimethylsulfoxide, acetone, dimethylacetamide, and the like, and their corresponding aqueous solutions.

In some embodiments, the aramid polymer includes one or more of poly (m-phenylene isophthalamide), poly (p-phenylene terephthalamide), and polyamide polymers containing heterocyclic structures. Specifically, poly (m-phenylene isophthalamide) (PMIA) is a polymer prepared by polycondensation of m-phenylene diamine and isophthaloyl dichloride, and is also called aramid 1313; poly (p-phenylene terephthalamide) (PPTA) is a fully para-polyaramid prepared by condensation polymerization of p-phenylene diamine and paraphthaloyl chloride, also known as aramid 1414. In the embodiment of the present application, the polyamide polymer containing heterocyclic structure can be piperazine aromatic polyamide, piperazine aromatic nylon, or polyquineAnd (3) an aliphatic diketone amide.

In some embodiments, the specific process of the gas-spray atomization treatment is: the aperture of the atomization hole is 0.1-8.0 mm, and the pressure of compressed gas is 0.1-1.0 MPa. The compression atomizer that gas spraying atomization was handled in this application embodiment adopts is current conventional compression atomizer, and the aperture in atomizing hole is 0.1 ~ 8.0mm, and compressed gas's operating pressure is 0.1 ~ 1.0MPa during atomizing, and the compressed gas who adopts includes one or several kinds in air, nitrogen gas, the argon gas.

In some embodiments, the preparation of the aramid polymer dispersion by dispersing the aramid polymer into the first solvent is specifically: dispersing the aramid polymer into a first solvent, and stirring for 1-60 min at 50-1000 rpm to obtain an aramid polymer dispersion liquid.

In some embodiments, the specific process of the superfine particle grinding treatment is as follows: the gap between the millstones is-100 mu m to 100 mu m, and the grinding times are 1 to 100 times. In the examples of the present application, the ultrafine grain grinding treatment was carried out by using an existing ultrafine grain refiner.

In some embodiments, the aramid polymer dispersion liquid is subjected to air-jet atomization treatment, sprayed into a second solvent, and stirred at 50-1000 rpm for 1-60 min to obtain the aramid micro-nanofiber dispersion liquid.

In some embodiments, the mass concentration of the aramid polymer dispersion is 0.01 to 20%.

In some embodiments, the mass concentration of the dimethylacetamide aqueous solution, the dimethylformamide aqueous solution, the dimethylsulfoxide aqueous solution and the acetone aqueous solution is 0-60%. In the examples of the present application, the mass concentration of an aqueous solution of dimethylacetamide or the like means the mass fraction of dimethylacetamide or the like in the whole solution, and the mass concentration of 0 means that the second solvent used is water.

Based on the same inventive concept, the embodiment of the application also provides the aramid nano-fiber prepared by the preparation method. The aramid nano-fiber prepared by the method is in a highly fibrillated hairiness shape, and the average diameter is less than 100 nm.

Based on the same inventive concept, the embodiment of the application also provides application of the aramid nano-fiber in preparation of composite reinforced materials, battery diaphragms, electric insulation nano-paper, flexible electronic devices and adsorption filter media.

Based on the same inventive concept, the embodiment of the present application further provides a method comprising the following steps:

mixing the prepared aramid nano-fiber, aramid chopped fiber and aramid pulp to obtain a fiber dispersion liquid;

defibering the fiber dispersion liquid, making sheets by a Kaiser method to prepare base paper, and carrying out hot pressing to obtain the aramid paper.

Specifically, the aramid chopped fibers used in the present application may be meta-polyamide fibers (aramid 1313) and para-polyamide fibers (aramid 1414); the mass ratio of the aramid nano-fiber to the aramid chopped fiber to the aramid pulp is 1 (4-5) to (4-5); the fluffing is carried out by the fluffer for 15000-25000 r; the hot pressing process specifically comprises the following steps: hot pressing at 180-220 deg.C under 3-6 Mpa for 1-2 min; before defibering, the fiber dispersion is diluted with water to a mass concentration of 0.1-0.3%.

The following further describes the methods for producing the aramid nanofibers and aramid paper of the present application with specific examples.

Example 1

The embodiment of the application provides a preparation method of aramid nano-fiber, which comprises the following steps:

s1, dispersing polyisophthaloyl metaphenylene diamine in a dimethylacetamide solvent at room temperature, and stirring at the rotating speed of 500rpm for 10min to obtain an aramid polymer dispersion liquid with the mass fraction of 10%;

s2, spraying the aramid polymer dispersion liquid in the S1 after air spraying atomization treatment into water, and stirring for 60min at the rotating speed of 500rpm to obtain an aramid micro-nanofiber dispersion liquid;

s3, carrying out ultramicro-grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain aramid fiber nano fibers;

wherein, the gas-spray atomization treatment process comprises the following steps: the aperture of the atomization hole is 0.1mm, the working pressure of compressed gas during atomization is 0.1MPa, and the adopted compressed gas is air;

the specific process of the superfine particle grinding treatment comprises the following steps: the gap between the millstones is 100 μm, and the grinding times are 100 times.

Example 2

The embodiment of the application provides a preparation method of aramid nano-fiber, which comprises the following steps:

s1, dispersing polyisophthaloyl metaphenylene diamine in a dimethylacetamide solvent at room temperature, and stirring at the rotating speed of 500rpm for 10min to obtain an aramid polymer dispersion liquid with the mass fraction of 10%;

s2, spraying the aramid polymer dispersion liquid in the S1 into a dimethylacetamide aqueous solution after air spray atomization treatment, and stirring at the rotating speed of 1000rpm for 20min to obtain an aramid micro-nanofiber dispersion liquid;

s3, carrying out ultramicro-grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain aramid fiber nano fibers;

wherein, the gas-spray atomization treatment process comprises the following steps: the aperture of the atomization hole is 2mm, the working pressure of compressed gas during atomization is 0.6MPa, and the adopted compressed gas is air;

the specific process of the superfine particle grinding treatment comprises the following steps: the gap between the millstones is 10 mu m, and the grinding times are 10 times; the mass concentration of the dimethylacetamide aqueous solution was 50%.

Example 3

The embodiment of the application provides a preparation method of aramid nano-fiber, which comprises the following steps:

s1, dispersing polyisophthaloyl metaphenylene diamine in a dimethylacetamide solvent at room temperature, and stirring at the rotating speed of 500rpm for 20min to obtain an aramid polymer dispersion liquid with the mass fraction of 20%;

s2, spraying the aramid polymer dispersion liquid in the S1 into a dimethylacetamide aqueous solution after air spray atomization treatment, and stirring for 60min at the rotating speed of 500rpm to obtain an aramid micro-nanofiber dispersion liquid;

s3, carrying out ultramicro-grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain aramid fiber nano fibers;

wherein, the gas-spray atomization treatment process comprises the following steps: the aperture of the atomization hole is 8mm, the working pressure of compressed gas during atomization is 1.0MPa, and the adopted compressed gas is air;

the specific process of the superfine particle grinding treatment comprises the following steps: the gap between the millstones is-20 mu m, and the grinding times are 10 times; the mass concentration of the dimethylacetamide aqueous solution is 60%.

Example 4

The embodiment of the application provides a preparation method of aramid nano-fiber, which comprises the following steps:

s1, dispersing polyisophthaloyl metaphenylene diamine in a dimethylacetamide solvent at room temperature, and stirring at the rotating speed of 1000rpm for 1min to obtain an aramid polymer dispersion liquid with the mass fraction of 12%;

s2, spraying the aramid polymer dispersion liquid in the S1 into a dimethylacetamide aqueous solution after air spray atomization treatment, and stirring for 60min at the rotating speed of 100rpm to obtain an aramid micro-nanofiber dispersion liquid;

s3, carrying out ultramicro-grinding treatment on the aramid fiber micro-nano fiber dispersion liquid to obtain aramid fiber nano fibers;

wherein, the gas-spray atomization treatment process comprises the following steps: the aperture of the atomization hole is 5mm, the working pressure of compressed gas during atomization is 0.7MPa, and the adopted compressed gas is air;

the specific process of the superfine particle grinding treatment comprises the following steps: the gap between the millstones is-100 mu m, and the grinding times are 20 times; the mass concentration of the dimethylacetamide aqueous solution is 60%.

Performance testing

An SEM image of the surface morphology of the aramid nanofibers prepared in example 4 is shown in fig. 2. As can be seen from FIG. 2, the aramid nanofibers prepared by the method are in a hairiness shape and have a unique highly fibrillated structure.

The diameter frequency histogram of the aramid nanofibers prepared in example 4 is shown in fig. 3.

The results of the average diameter and the specific surface area of the aramid nanofibers prepared in test examples 1 to 4 are shown in table 1 below.

Table 1-mean diameter and specific surface area of the aramid nanofibers prepared in different examples

Examples	Average diameter (nm)	Specific surface area (m)2/g)
			Example 1	112.7	194.6
Example 2	72.7	274.3
			Example 3	52.4	369.1
Example 4	28.9	558.2

As can be seen from Table 1, the aramid nanofibers prepared in examples 1 to 4 of the present application have an average diameter of 28.9 to 112.7nm and a specific surface area of 194.6 to 558.2m²The size distribution range of the aramid nano-fiber is wide, and the controllable and adjustable size of the aramid nano-fiber can be realized by adjusting the concentration of the aramid polymer dispersion liquid, different air-jet atomization treatment processes and ultramicron grinding treatment.

Example 5

The embodiment of the application provides a preparation method of aramid paper, which comprises the following steps:

mixing the aramid nano-fiber, the meta-aramid chopped fiber and the aramid pulp prepared in the embodiment 1 to obtain a fiber dispersion liquid;

diluting the fiber dispersion liquid with water to a mass concentration of 0.1%;

after being dilutedThe fiber dispersion is defibered by a defibering machine of 20000r, and the defibered fiber is subjected to Kaiser method to make a sheet with a quantitative of 40g/m²Carrying out hot pressing on the base paper at 200 ℃ and 5MPa for 1min to obtain aramid paper;

wherein the mass ratio of the aramid nano-fiber to the aramid chopped fiber to the aramid pulp is 1:4.5: 4.5.

Example 6

The embodiment of the application provides a preparation method of aramid paper, which is the same as the embodiment 5 except that the used aramid nanofibers are the aramid nanofibers prepared in the embodiment 2.

Example 7

The embodiment of the application provides a preparation method of aramid paper, which is the same as the embodiment 5 except that the used aramid nanofibers are the aramid nanofibers prepared in the embodiment 3.

Example 8

The embodiment of the application provides a preparation method of aramid paper, which is the same as the embodiment 5 except that the used aramid nanofibers are the aramid nanofibers prepared in the embodiment 4.

Comparative example 1

The comparative example provides a preparation method of aramid paper, which comprises the following steps:

mixing meta-aramid chopped fibers and aramid pulp to obtain a fiber dispersion liquid;

diluting the fiber dispersion liquid with water to a mass concentration of 0.1%;

defibering the diluted fiber dispersion liquid with a defibering machine at 20000r, and making into sheet with Kaiser method to obtain the final product with a quantitative of 40g/m²Carrying out hot pressing on the base paper at 200 ℃ and 5MPa for 1min to obtain aramid paper;

wherein the mass ratio of the aramid chopped fibers to the aramid pulp is 5: 5.

The aramid papers prepared in examples 5 to 8 and comparative example 1 were tested for tensile strength, tear strength, electrical strength, and dielectric constant, and the results are shown in table 2 below.

The performance detection standard of the aramid paper related in the embodiment of the invention is as follows:

testing the tensile strength of the aramid paper by GB/T453-2002; the tearing strength is tested by GB/T455-2002; the electrical strength is tested by GB/T1408.1-2016; the dielectric constant was tested using GB/T1409-2006.

Testing the thermal shrinkage rate: the paper sample was cut into a 40X 40mm sample, treated in an oven at 300 ℃ for 1 hour, and the thermal shrinkage was calculated from the measured change in length according to the following formula: r ═ 1-L/L₀)*100％

R is thermal shrinkage, L is the side length of the square after heat treatment, L₀Is the original square side length.

Table 2-properties of aramid papers prepared in different examples

As can be seen from Table 2, the aramid nanofiber prepared by the invention has obvious application effect and wide application prospect in the field of high-strength high-temperature-resistant aramid paper.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.