CN111945480A

CN111945480A - Composite conductive paper containing carbon nano tube and preparation method thereof

Info

Publication number: CN111945480A
Application number: CN202010672576.8A
Authority: CN
Inventors: 行武壮太郎; 邓飞
Original assignee: Shenzhen Cone Technology Co ltd
Current assignee: Shenzhen Cone Technology Co ltd
Priority date: 2020-07-14
Filing date: 2020-07-14
Publication date: 2020-11-17
Anticipated expiration: 2040-07-14
Also published as: CN111945480B

Abstract

The invention relates to composite conductive paper containing carbon nano tubes and a preparation method thereof. The preparation method comprises the following steps: preparing modified nano-cellulose; mechanically mixing the modified nanocellulose and the carbon nanotubes in water to prepare a first suspension; dispersing the modified inorganic micro-nano particles in an organic solvent to prepare a second suspension; and depositing the first suspension, drying to prepare a first functional layer, depositing the second suspension on the first functional layer, drying to prepare a second functional layer, and obtaining the composite conductive paper containing the carbon nano tubes. The conductive paper can keep good and consistent conductivity in a large humidity range, so that the conductive paper can be well applied to electronic products.

Description

Composite conductive paper containing carbon nano tube and preparation method thereof

Technical Field

The invention relates to the field of conductive composite materials, in particular to composite conductive paper containing carbon nano tubes and a preparation method thereof.

Background

The conductive paper is paper with good conductivity, and can be widely used as antistatic packaging materials, electromagnetic shielding materials, planar heating materials, new energy and electrochemical materials, sensing and braking materials and the like. On one hand, the conductive paper can be used as electronic devices such as induction wallpaper, inductors and the like, and is attracted by people. On the other hand, paper has the advantages of high yield, low cost and reproducibility, can replace some existing electronic products and plastic substrates, and the porosity of the paper is superior to that of plastic films, so that the paper is widely applied.

Due to the excellent electric and thermal conductivity and mechanical property, the Carbon Nano Tube (CNT) has wide application prospect in many fields. However, the application of the method is premised on excellent dispersion in a solvent or a matrix, and the CNTs are easy to agglomerate due to van der Waals force, and the surfaces of the CNTs have high hydrophobicity and are difficult to be uniformly dispersed in a polar solvent, so that the application of the CNTs is limited.

In order to solve the dispersion of CNTs, there have been many attempts including chemical modification of CNTs and a shear force dispersion treatment using a surfactant, a binder, or the like. Using these methods, an interfacial layer is formed between the CNT surface and the solvent when the CNTs are dispersed in the solvent. The CNT dispersion mechanism is to disperse CNT roots by applying a shear force using the elasticity of the interface layer, thereby obtaining an interface layer having a nano-scale structure. At this time, as the amount of the CNTs increases and the CNT dispersion proceeds, the larger the surface area of the CNTs in contact with the solvent, i.e., the more the interface layer between the CNTs and the solvent, which results in higher viscosity. Therefore, as the dispersion proceeds and the amount of CNTs increases, CNTs are difficult to disperse, and a CNT dispersion having both a high CNT content and excellent dispersion cannot be obtained. While a high CNT content means an improvement in conductivity, it is necessary to develop a method for improving the dispersibility of CNTs by a simple treatment without lowering the conductivity of the CNT dispersion.

Cellulose is a natural macromolecule which exists most in nature, is a main component of plant cell walls, and has a chemical structure formed by connecting D-glucopyranose rings by beta- (1,4) glycosidic bonds, wherein each glucose ring is provided with 3 hydroxyl groups. Nanocellulose is a fiber with a diameter of nanometer grade obtained by processing natural plant fibers by chemical, physical or biological means, has excellent mechanical properties, huge specific surface area, high transparency, good biodegradability and stable chemical properties, and is valued by people in the fields of papermaking and the like. For cellulose which is not subjected to modification treatment, hydrogen bonds between cellulose molecules and in the cellulose molecules cause agglomeration of the cellulose molecules, so that the cellulose is generally modified, the hydrogen bonds are greatly damaged, the agglomeration is avoided, and the nano-cellulose is prepared. For example: nanocellulose obtained by treating cellulose using a chemical method. The chemical method mainly comprises a TEMPO oxidation method, an acidolysis method and the like. TEMPO is 2,2,6, 6-tetramethylpiperidine-1-oxide, which is weakly oxidizing and selectively oxidizes the primary hydroxyl groups of saccharide materials. TEMPO oxidation of cellulose is an effective method for chemically treating fibers to form nanocellulose, which has high crystallinity, uniform width and high aspect ratio, and is rich in sodium carboxylate on the surface, and when TEMPO oxidized nanocellulose is dispersed in water, electric double layer repulsion is formed between fibers due to ionization of sodium carboxylate, thereby stably dispersing cellulose nanofibers singly in water.

At present, a scheme that modified nanocellulose is used for dispersing carbon nanotubes to enable the carbon nanotubes to be uniformly dispersed is reported in documents, however, after the modified nanocellulose and the carbon nanotubes are mixed and prepared into conductive paper, the obtained conductive paper is sensitive to humidity, and the conductive paper has large conductivity difference in different humidity ranges, so that the conductive paper is not beneficial to application in electronic products.

Disclosure of Invention

Problems to be solved by the invention

Based on the above, the invention provides the preparation method of the composite conductive paper, and the obtained conductive paper has weaker humidity sensitivity, and can keep better and consistent conductivity in a larger humidity range, so that the conductive paper can be better applied to electronic products.

Means for solving the problems

The technical scheme of the invention is as follows:

a preparation method of composite conductive paper containing carbon nano tubes comprises the following steps:

preparing modified nano-cellulose;

mechanically mixing the modified nanocellulose and the carbon nanotubes in water to prepare a first suspension;

dispersing the modified inorganic micro-nano particles in an organic solvent to prepare a second suspension;

depositing the first suspension, drying to prepare a first functional layer, depositing the second suspension on the first functional layer, and drying to prepare a second functional layer;

obtaining the composite conductive paper containing the carbon nano tube.

In a preferred embodiment, the surface of the modified inorganic micro-nano particle comprises hydrophobic groups and hydroxyl groups.

In a preferred embodiment, the modified inorganic micro-nano particles are silane coupling agent modified inorganic micro-nano particles;

the inorganic nanoparticles are selected from TiO₂、SiO₂And ZnO.

In a preferred embodiment, the modified inorganic micro-nano particles have an average particle size of 5nm to 100 nm.

In a preferred embodiment, the diameter of the modified nanocellulose is 3nm to 8nm, and the aspect ratio is 10 to 1000.

In a preferred embodiment, the carbon nanotubes have a diameter of 6nm to 10nm and a length of 50 μm to 400 μm.

In a preferred embodiment, the content of the modified inorganic micro-nano particles in the second suspension is 0.1g/mL to 1 g/mL.

In a preferred embodiment, the organic solvent is selected from one or more of absolute ethyl alcohol, acetone, toluene, tetrahydrofuran and ethyl acetate.

In a preferred embodiment, in the first suspension, the modified nanocellulose accounts for 0.5 wt% to 2 wt%, and the carbon nanotubes accounts for 0.2 wt% to 1 wt%.

In a preferred embodiment, the modified nanocellulose has an oxidizing group content of 0.2mmol/g to 2.22 mmol/g;

the oxidizing groups are carboxyl and aldehyde groups.

In a preferred embodiment, the modified nanocellulose has a crystallinity of 70% to 90%.

In a preferred embodiment, the preparation method of the modified nanocellulose comprises the following steps:

dispersing cellulose, nitric oxide and an oxidation auxiliary agent in water, stirring for reaction, controlling the pH value of the system to be 8-11, and purifying.

In a preferred embodiment, the nitroxide is TEMPO.

In a preferred embodiment, the oxidation aid is sodium bromide and sodium hypochlorite.

The invention also provides the composite conductive paper containing the carbon nano tube.

The technical scheme is as follows:

the structure of the composite conductive paper containing the carbon nano tubes comprises a first functional layer and a second functional layer deposited on the first functional layer;

the first functional layer comprises a modified nanocellulose and carbon nanotube composite;

the second functional layer comprises modified inorganic micro-nano particles.

ADVANTAGEOUS EFFECTS OF INVENTION

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, the first suspension containing modified nano-cellulose and carbon nano-tubes and the second suspension containing modified inorganic micro-nano particles are sequentially deposited to form two functional layers, so that the composite conductive paper is prepared, and the composite conductive paper has weak sensitivity to humidity and can keep good and consistent conductivity in a large humidity range, so that the composite conductive paper can be better applied to electronic products.

Furthermore, the sizes of the modified nanofiber material, the carbon nano tube and the modified inorganic micro-nano particles are adjusted, so that the raw materials are dispersed more uniformly, and the conductivity of the conductive paper is improved.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The technical scheme of the invention is as follows:

s1, preparing modified nano cellulose;

s2, mechanically mixing the modified nano-cellulose and the carbon nano-tubes in water to prepare a first suspension;

s3, dispersing the modified inorganic micro-nano particles in an organic solvent to prepare a second suspension;

and S4, depositing the first suspension, drying, preparing a first functional layer, depositing the second suspension on the first functional layer, and drying to prepare a second functional layer.

Specifically, in the step S1, the modified nanocellulose is prepared using cellulose as a raw material. The cellulose is derived from various plants in nature, such as wood, cotton, hemp, straw, wheat straw, etc. As can be understood, the primary cellulose is subjected to treatments such as swelling and pulping to increase the surface area, which is beneficial to the dissociation of hydrogen bonds inside cellulose macromolecules and between molecules, thereby improving the efficiency of subsequent oxidation reaction and improving the yield.

The method of modification is preferably: and (2) carrying out oxidation modification by using nitric oxide, specifically, taking the cellulose pulp, adding nitric oxide to carry out oxidation modification on cellulose, simultaneously adding an oxidation auxiliary agent, adjusting the pH value to obtain a modified nano cellulose solution, and purifying.

Among them, cellulose can be oxidized using TEMPO-containing nitroxides such as TEMPO, 4-acetylamino-TEMPO, 4-carboxy-TEMPO, 4-hydroxy-TEMPO, 4-oxo-TEMPO, 4-methoxy-TEMPO and 4-phosphonooxy-TEMPO. Preferably, the degree of fiber is oxidized using TEMPO, 4-methoxy-TEMPO and 4-acetamido-TEMPO, the reaction time is short, and the carboxyl content of the product is high. As the reaction proceeds, carboxyl groups are continuously generated on the surface of the fiber and ionization occurs, so that the pH value of the system is continuously fluctuated. Under the alkaline condition, the TEMPO oxidation system has great damage and degradation effects on cellulose, and compared with the TEMPO, the 4-acetamido-TEMPO oxidation system still keeps stronger reaction activity under the condition of smaller pH, thereby effectively avoiding the degradation of the cellulose, preventing the excessive reduction of the polymerization degree of the fiber, and ensuring the strength of the fiber while increasing the water solubility of the fiber.

TEMPO is a water-soluble stable nitroxyl radical that can be used to selectively catalyze the oxidation of primary hydroxyl groups of polysaccharides to carboxyl groups. In aqueous suspension, the TEMPO-oxidized nanocellulose can be broken down into individual pieces by mild mechanical treatment, since the high density carboxyl groups introduced on the fiber surface are anionically charged in water, and the electrostatic repulsion between them in water can effectively act on and promote effective dissociation of the nanocellulose. Meanwhile, the TEMPO oxidation reaction has mild conditions, simple operation, low cost and little pollution. After being oxidized by TEMPO, the surface of the cellulose is hydrophilic and forms a nano-scale structure with water,

the oxidation assistant is selected from hypohalous acid or its salt, halous acid or its salt, phthalic acid or its salt, hydrogen peroxide, etc. Preferably alkali metal hypohalite, which can accelerate the oxidation speed, wherein for 1g of cellulose, the content of an oxidation auxiliary agent is 0.5-15 mmol, and the molar ratio of the usage amount to TEMPO is (10-20): 1.

the pH is controlled to be 8-11 by adopting 0.1M HCl or 0.5M NaOH.

The mixing process can adopt ultrasonic or high-pressure homogenization, local intense heat and high pressure are generated in a liquid phase reaction medium in a short time, the contact area between the fiber and a reaction reagent can be increased, high-energy oxidation reaction can be promoted, the carboxyl content can be improved by adopting the method, and the polymerization degree of the cellulose is not reduced.

The purification comprises washing with water, suction filtration, centrifugal dehydration, removal of unreacted hypochlorite and various byproducts, and preparation of a modified nano cellulose solution with a solid content of 0.1-0.3 wt%. If the solids content is too high, subsequent dispersion of the nanocellulose is difficult and requires a high energy.

dispersing cellulose, TEMPO and sodium bromide in water, then adding sodium hypochlorite, stirring for reaction, controlling the pH value of the system to be 8-11, and purifying.

The modified nano-fiber prepared by the steps has the oxidizing groups of carboxyl and aldehyde, the higher the content of the oxidizing groups is, the aggregation of nano-cellulose in water can be effectively prevented, the smaller the average fiber diameter is, and the more suitable the nano-cellulose is for the carbon nano-tube dispersion liquid. Wherein, the carboxyl content of the modified nano-cellulose is controlled by the adding amount of the oxidation auxiliary agent and the reaction time. Preferably, in the modified nano-cellulose, the content of the oxidized groups (carboxyl and aldehyde groups) is 0.2-2.2 mmol/g, so that the nano-cellulose can be stably dispersed in water, can form a certain acting force with the carbon nano-tube, and is suitable for dispersing the carbon nano-tube. If the oxidizing group is less than 0.2mmol/g, the nanocellulose cannot be effectively dispersed, the fiber diameter is large, and the effect of dispersing the carbon nanotube is poor.

In a preferred embodiment, the diameter of the modified nanocellulose is 3nm to 8nm, and the aspect ratio is 10 to 1000. The carbon nanotube film has similar diameter to the carbon nanotube, is easy to interact and tangle with the carbon nanotube, is beneficial to forming conductive paper with excellent and stable performance and uniform thickness, and has higher length-diameter ratio and is more beneficial to adsorbing and tangling the carbon nanotube.

In a preferred embodiment, the modified nanofiber has a crystallinity of 70% to 90%, and the higher the crystallinity, the more favorable the adsorption of the entangled carbon nanotubes.

And S2, adding deionized water into the prepared modified nano-cellulose to prepare a completely dispersed nano-cellulose solution, adding the carbon nano-tubes and the rest water, and fully dispersing in a stirrer to prepare a first suspension.

During the mechanical mixing, the pH is preferably maintained above 2, otherwise the nanocellulose will form a gel which is difficult to disperse.

The invention does not carry out chemical treatment on the carbon nano tube, does not damage the length structure of the carbon nano tube in the mechanical mixing process, ensures the integrity of the current path of the carbon nano tube and is beneficial to improving the conductive capability of the conductive paper. The carbon nano tube/modified nano cellulose composite is stably dispersed in the water solution without agglomeration due to the charges carried on the surface of the carbon nano tube. The carbon nano tube and the modified nano cellulose have interaction, specifically, counter ions on the surface of the modified nano cellulose can induce dipoles in carbon lattices of the carbon nano tube, and the surface charge of the modified nano cellulose can play a role in electrostatic stabilization, so that the aggregation of the carbon nano tube in water is prevented.

The stirrer may be a conventional stirrer, an ultrasonic disperser, a high shear stirrer, or the like.

In a preferred embodiment, in the first suspension, the modified nanofiber material accounts for 0.5 wt% to 2 wt%, and the carbon nanotube accounts for 0.2 wt% to 1 wt%.

The surface of the carbon nano tube is hydrophobic, so that an interface layer is difficult to form with water, and even if the adding amount of the carbon nano tube is increased, the interface layer with the water is not increased, so that the viscosity is not increased, and the carbon nano tube is easy to disperse.

S3, inorganic micro-nano particles such as TiO₂、SiO₂And ZnO has hydroxyl, and the hydroxyl can form hydrogen bonds with hydroxyl on the nano-cellulose, so that the inorganic micro-nano particles can be stably attached to the surface of the conductive paper. Through surface modification treatment, partial hydroxyl of the inorganic micro-nano particles is replaced by hydrophobic groups, so that the inorganic micro-nano particles with the surfaces containing hydrophobic groups and hydroxyl groups can be obtained,the surface energy is reduced, so that hydrophobicity is presented, and the sensitivity of the conductive paper to humidity is favorably improved.

In a preferred embodiment, the surface modification treatment is: adding a silane coupling agent into an aqueous solution containing inorganic micro-nano particles for mixing reaction. The silane coupling agent can be one or more selected from a chain system silane coupling agent, an alkyl acrylyl oxygen silane coupling agent, a vinyl silane coupling agent and an epoxy silane coupling agent. Organic functional groups in silanol which is a hydrolysate of the silane coupling agent replace hydrophilic groups of the inorganic micro-nano particles, and an organic molecular film is formed on the surfaces of the particles, so that the hydrophobic effect is achieved. One end of the structure of the silane coupling agent is a hydrophobic group, such as alkyl, vinyl, epoxy, alkyl acryloxy and the like, and the other end of the structure is a group capable of being hydrolyzed, such as halogen, alkoxy, acyloxy and the like, so that the silane coupling agent is hydrolyzed into corresponding silanol to be in covalent bond connection with the inorganic micro-nano particles to form the modified inorganic micro-nano particles. The mass ratio of the inorganic micro-nano particles to the silane coupling agent is 1: (0.05-0.20).

In a preferred embodiment, the modified inorganic micro-nano particles have an average particle size of 5nm to 100 nm. The diameters of the nano-cellulose and the carbon nano-tubes are similar to each other to form a uniform network structure, the modified inorganic micro-nano particles in the size range can be just filled in gaps among fibers, so that a uniform hydrophobic surface is formed on the surface of the conductive paper, meanwhile, the fiber structures of the nano-cellulose and the carbon nano-tubes cannot be damaged, and the framework structure formed by the modified nano-fiber material and the conductive network formed by the carbon nano-tubes are still maintained. The sizes of the modified nanofiber material, the carbon nano tube and the modified inorganic micro-nano particles are adjusted, so that the conductivity of the conductive paper is improved.

In a preferred embodiment, the content of the modified inorganic micro-nano particles in the second suspension is 0.1g/mL to 1 g/mL. The content of the modified inorganic micro-nano particles has an influence on the hydrophobic performance of the conductive paper. If the content of the modified inorganic micro-nano particles is low, the hydrophobic property of the modified inorganic micro-nano particles cannot be improved; if the content is too high, the conductivity of the conductive paper is affected, the dispersion is not good, and the improvement of the hydrophobic property is limited.

In a preferred embodiment, the organic solvent is selected from one or more of absolute ethyl alcohol, acetone, toluene, tetrahydrofuran and ethyl acetate. The inorganic micro-nano particles subjected to surface modification treatment have good compatibility and dispersibility in an organic system.

In a preferred embodiment, the dispersion may be carried out using a conventional stirrer, an ultrasonic disperser, a high shear stirrer, or the like. The dispersion mode can ensure that the modified inorganic micro-nano particles are in a good dispersion state and are not easy to flocculate.

In step S4, the solution deposition method includes, but is not limited to, vacuum filtration, spin coating, dip coating, spray coating, slot die coating, flexo printing, offset printing, screen printing, gravure printing, inkjet printing, etc.

And depositing the first suspension, drying to obtain a first functional layer, depositing the second suspension on the first functional layer, drying to obtain a second functional layer, and performing vacuum drying to obtain the composite conductive paper.

It can be understood that the first suspension is deposited, after moisture is dried, the modified nanocellulose forms a skeleton, the carbon nanotubes form a good conductive network structure, the carbon nanotubes and the skeleton are connected with each other, the diameters of the carbon nanotubes are similar, and the dried first functional layer is stable in structure and good in conductive effect.

When the second suspension is deposited, part of hydroxyl groups carried on the modified inorganic micro-nano particles of the second suspension can form hydrogen bonds with hydroxyl groups on the nanocellulose, so that the modified inorganic micro-nano particles are stably attached to the surface of the conductive paper.

In a preferred embodiment, when the second suspension is deposited, the modified inorganic micro-nano particles are uniformly deposited on the surface of the first functional layer, so as to provide a hydrophobic layer for the surface of the first functional layer. Because the modified inorganic micro-nano particles are granular, the modified inorganic micro-nano particles are beneficial to being uniformly carried in the network structure of the first functional layer, and the connectivity of the conductive network structure is not influenced, so that the composite conductive paper with good hydrophobic property, good conductive performance and stable structure is formed.

In a preferred embodiment, the deposition of the second suspension may be repeated 1 to 3 times, so as to ensure that the surface of the first functional layer is uniformly coated with the second functional layer.

The carbon nano tube provides a conductive path, the modified nano cellulose serves as a framework and provides mechanical strength, the carbon nano tube and the modified nano cellulose are connected with each other, the diameters of the carbon nano tube and the modified nano cellulose are similar, a continuous current path is provided, high conductivity is guaranteed, meanwhile, the modified inorganic micro-nano particles are uniformly dispersed on the outer surface, the whole conductive paper is subjected to hydrophobic treatment, the conductivity of the conductive paper is not influenced by the addition of the modified inorganic micro-nano particles, and the sensitivity of the conductive paper to humidity is improved, so that the conductive paper can be better applied to electronic products.

The invention also provides composite conductive paper containing carbon nano tubes, which structurally comprises a first functional layer and a second functional layer deposited on the first functional layer;

the second functional layer comprises modified inorganic micro-nano particles.

In the composite conductive paper containing the carbon nano tubes, the carbon nano tubes provide conductive paths, the modified nano cellulose serves as a framework and provides mechanical strength, the carbon nano tubes and the modified nano cellulose are mutually connected and have similar diameters, a continuous current path is provided, high conductivity is guaranteed, meanwhile, the modified inorganic micro-nano particles are uniformly dispersed on the outer surface, the whole conductive paper is subjected to hydrophobic treatment, the conductivity of the conductive paper is not influenced by the addition of the modified inorganic micro-nano particles, and the sensitivity of the conductive paper to humidity is improved, so that the conductive paper can be better applied to electronic products.

In the following, the raw materials mentioned in the following specific examples are all commercially available, and the instruments mentioned in the following specific examples are all those conventionally used in the art unless otherwise specified.

Example 1

The embodiment provides composite conductive paper and a preparation method thereof, and the preparation method comprises the following steps:

s1 preparation of modified nanocellulose

2g of undried bleached softwood pulp, 0.025g of TEMPO and 0.25g of sodium bromide were dispersed in 150 ml of water. Subsequently, 2.86g of a 13 wt% sodium hypochlorite solution was added so that 1g of wood pulp corresponded to 2.5mmol of sodium hypochlorite. During the reaction, 0.5M NaOH solution was added dropwise to maintain the pH at 10.5. When the pH no longer changed, the reaction was considered to have ended. After filtering the reaction product, washing with a sufficient amount of water and repeating the filtration 5 times, and centrifuging to remove water to obtain a modified fiber solution having a solid content of 25%. And then, adding deionized water into the modified fiber solution to prepare a 2 wt% modified fiber solution, and performing ultrasonic dispersion. After mixing, the viscosity of the slurry is significantly increased. Gradually adding water, and continuing to perform ultrasonic dispersion treatment until the solid content concentration reaches 0.15 wt%. And removing suspended substances by a centrifugal separation method to obtain a single dispersed modified nano-cellulose solution.

Tests show that the amount of the oxidized groups (aldehyde groups and carboxyl groups) in the obtained modified nanocellulose is 1.35mmol/g, the fiber diameter of the modified nanocellulose is 3-8 nm, and the length-diameter ratio is 10-1000.

S2 preparation of first suspension

33g of the modified nanocellulose solution with the solid content of 0.15 wt% was taken, 464.5g of water and 2.5g of CNT were added, and sufficiently dispersed in a mechanical stirrer, to obtain a first suspension.

Wherein the diameter of the CNT is 6 nm-10 nm, and the length of the CNT is 50 μm-400 μm.

S3 preparation of second suspension

Hydrophobic TiO₂The preparation method comprises the following steps: 0.5g of TiO was added to 15mL of deionized water₂After ultrasonic mixing, 10mL of fully hydrolyzed aqueous solution containing 0.075g of vinyltrimethoxysilane is added, the mixture reacts for 4 hours at the constant temperature of 70 ℃, and then centrifugal separation, cleaning and vacuum drying are carried out to obtain hydrophobic TiO₂。

0.5g of hydrophobic TiO is taken₂5mL of absolute ethanol is added, and ultrasonic dispersion is carried out to obtain a second suspension.

Wherein, the hydrophobic TiO₂Has an average particle diameter of 40 nm.

S4 preparation of composite conductive paper

Spraying the first suspension on a base, and drying for 4 hours in a vacuum drying oven at 60 ℃ to form a first functional layer;

and taking the second suspension, soaking the first functional layer in the second suspension to form a second functional layer, drying for 1h in a vacuum drying oven at 60 ℃, and repeating the steps of dip coating and drying for 1-3 times to obtain the carbon nanotube-containing composite conductive black paper.

Example 2

This example provides a composite conductive paper and a method for preparing the same, which is substantially the same as example 1 except that: the inorganic micro-nano particles are different in types and comprise the following steps:

s1 preparation of modified nanocellulose

S2 preparation of first suspension

S3 preparation of second suspension

Hydrophobic SiO₂The preparation method comprises the following steps: 0.5g of SiO was added to 15mL of deionized water₂After ultrasonic mixing, 10mL of a fully hydrolyzed aqueous solution containing 0.075g of vinyltrimethoxysilane is added, the mixture is reacted for 4 hours at a constant temperature of 70 ℃, and then centrifugal separation, cleaning and vacuum drying are carried out to obtain hydrophobic SiO₂。

0.5g of hydrophobic SiO is taken₂5mL of absolute ethanol is added, and ultrasonic dispersion is carried out to obtain a second suspension.

Wherein, the hydrophobic SiO₂Has an average particle diameter of 40 nm.

S4 preparation of composite conductive paper

Example 3

s1 preparation of modified nanocellulose

S2 preparation of first suspension

Wherein the CNT is 6nm to 10nm and 50 μm to 400 μm in length.

S3 preparation of second suspension

The preparation method of the hydrophobic ZnO comprises the following steps: 0.5g of ZnO is added into 15mL of deionized water for ultrasonic mixing, 10mL of fully hydrolyzed aqueous solution containing 0.075g of vinyl trimethoxy silane is added for constant-temperature reaction at 70 ℃ for 4 hours, and then centrifugal separation, cleaning and vacuum drying are carried out to obtain the hydrophobic ZnO.

And taking 0.5g of hydrophobic type, adding 5mL of absolute ethyl alcohol, and performing ultrasonic dispersion to obtain a second suspension.

Wherein the hydrophobic ZnO has an average particle diameter of 40 nm.

S4 preparation of composite conductive paper

Example 4

This example provides a composite conductive paper and a method for preparing the same, which is substantially the same as example 1 except that: the sizes of the carbon nano tube and the inorganic micro-nano particles are different, and the steps are as follows:

s1 preparation of modified nanocellulose

S2 preparation of first suspension

S3 preparation of second suspension

Hydrophobic TiO₂The preparation method comprises the following steps: 0.5g of TiO was added to 15mL of deionized water₂After ultrasonic mixing, 10mL of a fully hydrolyzed mixture was addedThe aqueous solution containing 0.075g of vinyl trimethoxy silane is reacted for 4 hours at the constant temperature of 70 ℃, and then centrifugal separation, cleaning and vacuum drying are carried out to obtain the hydrophobic TiO₂。

Wherein, the hydrophobic TiO₂Has an average particle diameter of 80 nm.

S4 preparation of composite conductive paper

Comparative example 1

This comparative example provides a composite conductive paper and a method of making the same, substantially the same as example 1, except that: modified inorganic micro-nano particles are not added, and the method comprises the following steps:

s1 preparation of modified nanocellulose

S2 preparation of first suspension

S3 preparation of composite conductive paper

And (3) spraying the first suspension on a base, and drying for 4h in a vacuum drying oven at 60 ℃ to form a first functional layer, namely the carbon nanotube-containing composite conductive black paper.

Comparative example 2

This comparative example provides a composite conductive paper and a method of making the same, substantially the same as example 1, except that: replacing modified inorganic micro-nano particles with polytetrafluoroethylene powder, and the steps are as follows:

s1 preparation of modified nanocellulose

S2 preparation of first suspension

S3 preparation of second suspension

And adding 0.5g of polytetrafluoroethylene powder into 5mL of absolute ethyl alcohol, and performing ultrasonic dispersion to obtain a second suspension.

S4 preparation of composite conductive paper

And spraying the first suspension on a base, drying for 4h at 60 ℃ in a vacuum drying oven to form a first functional layer, spraying the second suspension on two sides of the first functional layer to form a second functional layer, and drying for 1h at 60 ℃ in the vacuum drying oven to obtain the composite conductive black paper.

Performance testing

3 parts of the composite conductive paper prepared in each of examples 1 to 4 and comparative examples 1 and 2 were taken, and the following operations were performed:

the first part is placed for 24 hours in a closed environment at the relative humidity of 11% RH and the temperature of 25 ℃, and after being taken out, the test piece is subjected to volume resistivity, surface resistivity and tensile strength test.

And the second part is placed for 24 hours in a closed environment at the relative humidity of 57% RH and the temperature of 25 ℃, and the test piece is taken out to be tested for volume resistivity, surface resistivity and tensile strength.

And the third part is placed for 24 hours in a sealed environment at the relative humidity of 95% RH and the temperature of 25 ℃, and the test piece is taken out to be tested for volume resistivity, surface resistivity and tensile strength.

Measuring the volume resistivity and the surface resistivity by adopting a four-probe resistivity tester; the tensile strength test adopts the GB/T12914 standard.

The volume resistivity, surface resistivity and tensile strength of the 18 test pieces are summarized in Table 1.

TABLE 1

As can be seen from table 1, the volume resistivity and the surface resistivity of the composite conductive paper prepared in examples 1 to 4 are relatively constant in different humidity environments, the conductivity has no great change, and the composite conductive paper has good conductivity and strong mechanical properties. Comparative example 1 the surface of the conductive paper was not modified, and the conductive paper had a large difference in conductivity change at different humidities. Although the composite conductive paper of comparative example 2 was sprayed with hydrophobic polytetrafluoroethylene powder, the conductive paper exhibited different conductivity at different humidity and still had humidity sensitivity.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The preparation method of the composite conductive paper containing the carbon nano tube is characterized by comprising the following steps of:

preparing modified nano-cellulose;

obtaining the composite conductive paper containing the carbon nano tube.

2. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 1, wherein the carbon nanotubes have a diameter of 6nm to 10nm and a length of 50 μm to 400 μm.

3. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 1, wherein the surface of the modified inorganic micro-nano particles comprises hydrophobic groups and hydroxyl groups.

4. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 3, wherein the modified inorganic micro-nano particles are silane coupling agent-modified inorganic micro-nano particles;

the inorganic micro-nano particles are selected from TiO₂、SiO₂Or one or more of ZnO.

5. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 4, wherein the modified inorganic micro-nano particles have an average particle size of 5nm to 100 nm.

6. The method for preparing the composite conductive paper containing the carbon nanotubes in claim 5, wherein the content of the modified inorganic micro-nano particles in the second suspension is 0.1g/mL-1 g/mL.

7. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 1, wherein the method for preparing the modified nanocellulose comprises the following steps:

8. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 7, wherein the diameter of the modified nanocellulose is 3nm to 8nm, and the aspect ratio is 10 to 1000.

9. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 7, wherein the modified nanocellulose accounts for 0.5 wt% to 2 wt% of the first suspension, and the carbon nanotubes accounts for 0.2 wt% to 1 wt%.

10. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 7, wherein the modified nanocellulose has an oxidizing group content of 0.2mmol/g to 2.22 mmol/g;

the oxidizing groups are carboxyl and aldehyde groups.

11. The method for preparing the carbon nanotube-containing composite conductive paper according to claim 7, wherein the modified nanocellulose has a crystallinity of 70% to 90%.

12. The composite conductive paper containing the carbon nano tubes is characterized by structurally comprising a first functional layer and a second functional layer deposited on the first functional layer;

the second functional layer comprises modified inorganic micro-nano particles.