Aramid nanofiber-based insulation paper and preparation method thereof

Patent metadata

Field	Value
Publication number	US-11319675-B2
Application number	US-202016943756-A
Country	US
Kind code	B2
Filing date	Jul 30, 2020
Priority date	Aug 26, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

The present invention provides an aramid nanofiber (ANF)-based insulation paper and a preparation method thereof, and relates to the technical field of composite insulation material. The ANF-based insulation paper provided in the present invention includes ANFs and inorganic insulation materials. The ANFs have a bifurcated geometry and form a three-dimensional network structure, and the inorganic insulation materials are distributed in the three-dimensional network structure. The ANF paper provided in the present invention, with optimal electrical and mechanical properties and excellent insulation and flame-resistance, can replace mica tapes, aramid papers and aramid mica papers on the current market for insulation, and thus the thickness for insulation can be reduced. The present invention provides a method for preparing the ANF-based insulation paper. The preparation method provided in the present invention is simple, has excellent operability, and can be used for continuous preparation, thereby facilitating the realization of industrial production.

First claim

What is claimed is:

1. An aramid nanofiber (ANF)-based insulation paper, comprising ANFs and inorganic insulation materials, wherein the ANFs have a bifurcated geometry and form a three-dimensional network structure, and the inorganic insulation materials are distributed in the three-dimensional network structure.

2. The ANF-based insulation paper according to claim 1 , wherein the ANFs comprise para-aramid fibers and/or meta-aramid fibers, and have a diameter of 3 nm to 20 nm.

3. The ANF-based insulation paper according to claim 1 , wherein the inorganic insulation materials comprise one or more of muscovite, phlogopite, fluorophlogopite, synthetic mica and boron nitride, and account for 30% to 70% of the mass of the ANF-based insulation paper.

4. A method for preparing the ANF-based insulation paper according to claim 1 , comprising the following steps:
(1) mixing a strong alkali, dimethyl sulfoxide and aramid fibers to obtain a dispersion of ANFs;
(2) mixing dimethyl sulfoxide and inorganic insulation materials to obtain a dispersion of inorganic insulation materials;
(3) mixing the dispersion of ANFs and the dispersion of inorganic insulation materials to obtain a sol;
(4) performing solvent exchange on the sol with water to obtain a hydrogel; and
(5) drying the hydrogel to obtain an ANF-based insulation paper;
wherein, steps (1) and (2) can be performed in any order.

5. The preparation method according to claim 4 , wherein the strong alkali in step (1) is one or more of potassium hydroxide, potassium ethoxide and potassium tert-butoxide; the strong alkali and dimethyl sulfoxide are used at a mass ratio of 1:(9-300); and the strong alkali and aramid fibers are used at a mass ratio of 1:(1-3).

6. The preparation method according to claim 4 , wherein, in step (2), dimethyl sulfoxide and inorganic insulation materials are used at a mass ratio of 1:(0.003-0.05).

7. The preparation method according to claim 4 , wherein, in step (3), the dispersion of ANFs and the dispersion of inorganic insulation materials are used at a mass ratio of 1:(0.5-3).

8. The preparation method according to claim 4 , wherein, the performing solvent exchange on the sol with water in step (4) specifically comprises: pouring the sol into a mold and then immersing the mold in water for solvent exchange; or,
letting the sol pass through a continuous injection device for solvent exchange with water.

9. The preparation method according to claim 8 , wherein the continuous injection device comprises an injector, an outlet mold, a conveyor belt, and a sink,
wherein the outlet of the injector communicates with the inlet of the outlet mold, the outlet of the outlet mold is close to the conveyor belt, and the outlet mold and the conveyor belt are disposed in the sink;
and in application, the sol is continuously injected through the injector; the solvent is exchanged with water in the sink after the sol flows through the outlet mold; and the formed hydrogel is transferred out of the sink by the conveyor belt.

10. The preparation method according to claim 4 , wherein the drying in step (5) is performed at 25° C. to 40° C. for 48 h to 120 h.

11. A method for preparing the ANF-based insulation paper according to claim 2 , comprising the following steps:
(1) mixing a strong alkali, dimethyl sulfoxide and aramid fibers to obtain a dispersion of ANFs;
(2) mixing dimethyl sulfoxide and inorganic insulation materials to obtain a dispersion of inorganic insulation materials;
(3) mixing the dispersion of ANFs and the dispersion of inorganic insulation materials to obtain a sol;
(4) performing solvent exchange on the sol with water to obtain a hydrogel; and
(5) drying the hydrogel to obtain an ANF-based insulation paper;
wherein, steps (1) and (2) can be performed in any order.

12. The preparation method according to claim 11 , wherein the strong alkali in step (1) is one or more of potassium hydroxide, potassium ethoxide and potassium tert-butoxide; the strong alkali and dimethyl sulfoxide are used at a mass ratio of 1:(9-300); and the strong alkali and aramid fibers are used at a mass ratio of 1:(1-3).

13. The preparation method according to claim 11 , wherein, in step (2), dimethyl sulfoxide and inorganic insulation materials are used at a mass ratio of 1:(0.003-0.05).

14. The preparation method according to claim 11 , wherein, in step (3), the dispersion of ANFs and the dispersion of inorganic insulation materials are used at a mass ratio of 1:(0.5-3).

15. The preparation method according to claim 11 , wherein, the performing solvent exchange on the sol with water in step (4) specifically comprises: pouring the sol into a mold and then immersing the mold in water for solvent exchange; or,
letting the sol pass through a continuous injection device for solvent exchange with water.

16. A method for preparing the ANF-based insulation paper according to claim 3 , comprising the following steps:
(1) mixing a strong alkali, dimethyl sulfoxide and aramid fibers to obtain a dispersion of ANFs;
(2) mixing dimethyl sulfoxide and inorganic insulation materials to obtain a dispersion of inorganic insulation materials;
(3) mixing the dispersion of ANFs and the dispersion of inorganic insulation materials to obtain a sol;
(4) performing solvent exchange on the sol with water to obtain a hydrogel; and
(5) drying the hydrogel to obtain an ANF-based insulation paper;
wherein, steps (1) and (2) can be performed in any order.

17. The preparation method according to claim 16 , wherein the strong alkali in step (1) is one or more of potassium hydroxide, potassium ethoxide and potassium tert-butoxide; the strong alkali and dimethyl sulfoxide are used at a mass ratio of 1:(9-300); and the strong alkali and aramid fibers are used at a mass ratio of 1:(1-3).

18. The preparation method according to claim 16 , wherein, in step (2), dimethyl sulfoxide and inorganic insulation materials are used at a mass ratio of 1:(0.003-0.05).

19. The preparation method according to claim 16 , wherein, in step (3), the dispersion of ANFs and the dispersion of inorganic insulation materials are used at a mass ratio of 1:(0.5-3).

20. The preparation method according to claim 16 , wherein, the performing solvent exchange on the sol with water in step (4) specifically comprises: pouring the sol into a mold and then immersing the mold in water for solvent exchange; or,
letting the sol pass through a continuous injection device for solvent exchange with water.

Assignees

• Univ Hunan

Inventors

• Wang Jianfeng
• Zeng Fanzhan
• Xiao Guang

Classifications

• D21H17/68

  siliceous, e.g. clays · CPC title

• D21H17/05

  containing elements other than carbon and hydrogen only · CPC title

• D21H17/67

  Water-insoluble compounds, e.g. fillers, pigments · CPC title

• D21H15/02

  characterised by configuration · CPC title

• D21H13/26 Primary

  Polyamides; Polyimides · CPC title