CN113417137A

CN113417137A - Preparation method of water-based high-conductivity coating

Info

Publication number: CN113417137A
Application number: CN202110655283.3A
Authority: CN
Inventors: 叶长怀; 王悦; 廖耀祖
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2021-09-21

Abstract

The invention provides a preparation method of a water-based high-conductivity coating. Deionized water is used as a solvent, biomass chitosan and succinic acid are used as raw materials to prepare an organic salt solution, and conductive particles are added to fully disperse to obtain the uniform and stable water-based high-conductivity coating. The coating is coated on different base materials in a dropping coating and dipping mode, and the coating is dried and then placed in a high-temperature environment for a period of time to enable the bio-based organic salt to be crosslinked, so that the high-conductivity coating is obtained. The coating has excellent electromagnetic shielding effect, can resist water and organic solvents, can be heated to more than 50 ℃ under the low voltage of 1.5V when being loaded on a flexible fabric, and is a multifunctional water-based high-conductivity coating.

Description

Preparation method of water-based high-conductivity coating

Technical Field

The invention relates to the technical field of a method for preparing a water-based high-conductivity coating, which is mainly applied to the field of electromagnetic shielding and heatable fabrics.

Background

Electromagnetic pollution can be generated in the radiation process of electromagnetic waves, and the electromagnetic pollution can bring harm such as electromagnetic information leakage, electromagnetic communication interference, animal and plant health influence and the like. With the development of 5G and other communication technologies and various electronic devices, the problem of electromagnetic pollution becomes more serious and becomes a hot problem to be solved urgently. In order to reduce or even avoid the harm to instruments and equipment and human health caused by electromagnetic pollution, the research and development of flexible electromagnetic shielding materials have become the focus of extensive attention of researchers. On the basis of meeting the requirement of shielding electromagnetic waves, the flexible electromagnetic shielding material can be applied to wearable electronic equipment due to the special flexibility of the flexible electromagnetic shielding material so as to reduce the harm of the electromagnetic waves to human bodies.

The conductive coating can be conveniently coated on different matrixes by various film-making methods such as spraying, dipping and the like, and can effectively protect electromagnetic waves by dissipating electromagnetic wave energy in modes such as dielectric loss, resistance loss and the like. The conductive coating is light and flexible, and can be effectively combined with a flexible substrate to prepare a wearable flexible electromagnetic shielding material, so that the conductive coating is widely researched. However, the conductive coating usually uses an organic solvent as a dispersion liquid, which not only has high cost and pollutes the environment, but also has great harm to human bodies due to residual solvent. In the daily use process, the conductive coating also needs to have good stability and durability in meeting the performance requirements, and has basic requirements on water washing resistance, organic solvent resistance and the like so as to meet the requirements of various use scenes.

Disclosure of Invention

The invention discloses a preparation method of a water-based high-conductivity coating, which can effectively protect electromagnetic waves, can resist water and organic solvents and has good stability. Can rapidly generate heat under low voltage, and can be applied to wearable portable heaters. And the process method is simple and convenient, the equipment requirement is simple, and the preparation process is green and pollution-free.

A preparation method of a water-based high-conductivity coating comprises the following steps:

step 1: adding deionized water into chitosan, adding a pre-dissolved succinic acid solution, and stirring overnight;

step 2: carrying out suction filtration on the solution, carrying out rotary evaporation, adding methanol for precipitation, carrying out suction filtration after fully stirring, and carrying out vacuum drying to obtain succinic acid-chitosan biomass organic salt;

and step 3: dissolving succinic acid-chitosan biomass organic salt in deionized water, and fully stirring to obtain a biomass succinic acid-chitosan organic salt solution;

and 4, step 4: adding the silver nanowire solution into the biomass succinic acid-chitosan salt solution, and fully stirring to obtain uniform and stable water-based high-conductivity coating;

and 5: taking a polyimide film, taking the water-based high-conductivity coating by using a liquid-transfering gun, dripping the water-based high-conductivity coating on the polyimide film, drying the polyimide film by using a heating table, and raising the temperature to a high temperature for a certain time to obtain a water-based high-conductivity coating taking the polyimide film as a substrate;

step 6: taking a piece of flexible fabric, respectively ultrasonically cleaning the flexible fabric with deionized water and ethanol in sequence, and drying the flexible fabric in a vacuum drying oven;

and 7: soaking the fabric in uniformly dispersed conductive coating, soaking for multiple times, extruding out redundant coating, and drying in a drying oven;

and 8: placing the dried fabric in a drying oven in a high-temperature environment, and keeping for a certain time;

and step 9: and repeating the steps of dipping and high-temperature crosslinking until the load capacity of the conductive coating on the conductive fabric reaches a certain value, thereby obtaining the water-based high-conductivity coating taking the fabric as the substrate.

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

(1) the invention adopts the water solution formed by the bio-based organic salt as the polymer precursor of the coating, the conductive particles can be dispersed in the water phase without surface modification, and the conductive composite coating with high crosslinking degree is obtained by a simple thermal crosslinking method after coating, so that the invention has the characteristics of simple process and green and environment-friendly preparation process;

(2) the water-based high-conductivity coating prepared by the invention has excellent electromagnetic shielding effect, and can meet the basic electromagnetic shielding protection requirement only in the thickness of tens of microns; and is suitable for various substrates, such as fabric substrates, to obtain flexible electromagnetic shielding materials or portable heating fabrics;

(3) the waterborne high-conductivity coating prepared by the method has good binding force with various matrixes, excellent stability and durability, and good water resistance and solvent resistance, and the conductive fabric prepared based on the conductive coating meets the requirement of water washing.

(4) The invention takes deionized water as a solvent, takes biomass chitosan and succinic acid as raw materials to prepare an organic salt solution, and adds conductive particles to fully disperse to obtain the uniform and stable water-based high-conductivity coating. The coating is coated on different base materials in a dropping coating and dipping mode, and the coating is dried and then placed in a high-temperature environment for a period of time to enable the bio-based organic salt to be crosslinked, so that the high-conductivity coating is obtained. The coating has excellent electromagnetic shielding effect, can resist water and organic solvents, can be heated to more than 50 ℃ under the low voltage of 1.5V when being loaded on a flexible fabric, and is a multifunctional water-based high-conductivity coating.

Drawings

FIG. 1 is a diagram of the formation process of succinic acid-chitosan organic salt solution.

FIG. 2 shows succinic acid-chitosan organic salt (example 1)¹H-NMR chart.

FIG. 3 is an infrared spectrum of succinic acid-chitosan organic salt (example 1).

FIG. 4 is a SEM image of a cross section of an aqueous high-conductivity coating with a polyimide film as a substrate.

Fig. 5 is a graph of electromagnetic shielding effectiveness of a fabric-based aqueous highly conductive coating.

Detailed Description

The invention is further illustrated by the following examples, which are intended only for a better understanding of the contents of the invention and do not limit the scope of the invention.

A preparation method of a water-based high-conductivity coating is characterized by comprising the following steps:

Preferably, the biomass organic salt in step 1 of the invention is succinic acid-chitosan, the deacetylation degree of the chitosan is more than or equal to 75%, and the molecular weight is 310-375 kg/mol.

Preferably, the substrate in step 1 of the present invention is a high temperature resistant polyimide film or fabric.

Preferably, the conductive particles in step 1 of the present invention are silver nanowires, wherein the diameter of the silver nanowires is 2 nm, the length of the silver nanowires is 20 μm, and the concentration of the silver nanowires is 10 mg/ml.

Preferably, the concentration of the biomass succinic acid-chitosan organic salt solution in the step 3 of the invention is 0.6 wt%.

Preferably, the concentration of the conductive particles in the aqueous highly conductive coating in step 4 of the present invention is 30 wt% to 80 wt%.

Preferably, the thickness of the polyimide film in step 5 of the invention is 0.1 mm, the volume of the water-based conductive coating which is taken by drop coating is 1-2 ml, and the temperature is heated to 180-195 ℃ and kept for 10-15 min.

Preferably, the thickness of the flexible fabric in step 6 of the present invention is 0.3 mm.

Preferably, the drying temperature in the drying oven in step 7 of the invention is heated to 180-220 ℃ and kept for 10-20 min.

Preferably, the flexible fabric is immersed in the aqueous high-conductivity coating in the step 7 of the invention, and the excess coating is squeezed out by using tweezers, wherein the loading amount reaches 0.30-2.57 vol%.

Example 1

Step 1: 2.3 g of chitosan was weighed into 1000 ml of deionized water, and a succinic acid (0.54 g) solution previously dissolved in 200 ml of deionized water was added and stirred overnight.

Step 2: carrying out suction filtration and rotary evaporation on the solution, adding 500 ml of methanol for precipitation, stirring for 12 hours, carrying out suction filtration, and carrying out vacuum drying to obtain the biomass succinic acid-chitosan organic salt

And step 3: 0.3 g of succinic acid-chitosan organic salt is dissolved in 50 ml of deionized water, and the solution is fully stirred to obtain 0.6 wt% of biomass succinic acid-chitosan organic salt solution.

And 4, step 4: and (3) taking 2.57 ml of silver nanowire solution to 10 ml of biomass succinic acid-chitosan organic salt solution, and stirring for 12 hours to obtain the 30 wt% conductive ink.

And 5: a piece of polyimide film (1.5 cm x 2 cm) is taken, a liquid transfer gun is used for taking 1.5 ml of conductive paint to be dripped on the polyimide film, the polyimide film is dried at a heating table at 60 ℃, and then the temperature is raised to 180 ℃ for ten minutes to obtain the water-based high-conductivity coating taking the polyimide film as a substrate.

Step 6: a piece of flexible fabric (1.5 mm x 2 mm), deionized water and ethanol are respectively subjected to ultrasonic treatment for 0.5 h, and the fabric is dried in a vacuum drying oven at 60 ℃.

And 7: soaking the fabric in uniformly dispersed water-based high-conductivity coating, soaking for multiple times, extruding out redundant coating, and drying in a drying oven at 60 DEG C

And 8: the dried fabric was placed in an oven at 195 ℃ and held for 15 min.

And step 9: and repeating the steps of dipping and high-temperature crosslinking until the loading amount of the conductive coating on the conductive fabric is 0.3 vol% to obtain the water-based high-conductivity coating taking the fabric as the substrate.

The synthesis mechanism of the succinic acid-chitosan organic salt obtained in this example is shown in fig. 1, and the amine group of chitosan and the carboxyl group of succinic acid may undergo dehydration condensation at high temperature.

Preparation of succinic acid-chitosan organic salt obtained in this example¹The results of the H-NMR measurement are shown in FIG. 2, and NH-CO-: NH-can be estimated from the hydrogen spectrum₃ ⁺The ratio of COO-is 0.3:1: 0.7.

Preparation of succinic acid-chitosan organic salt obtained in this example¹The results of H-NMR measurement are shown in FIG. 3, and the spectrum of pure chitosan shows 889 cm^-1、1018 cm^-1、1147 cm^-1、1373 cm^-1、1537 cm^-1Several characteristic peaks of (a). SA-chitosan salt at 3430 cm^-1There are multiple overlapping, broadened characteristic absorption peaks near, due to O-H and N-H tensile vibrations. At 2870 cm^-1Axial C-H stretching of the polymer was observed. For crosslinked succinic acid-chitosan polymers, the carboxyl group of succinic acid and the amine group of chitosan are dehydrated and condensed at high temperature to obtain an amide bond. 1683 cm^-1And 1536 cm^-1The peaks of (a) are the stretching vibration and the shearing vibration of the amide bond C = O and N-H, respectively.

The electromagnetic shielding effectiveness of the aqueous high-conductivity coating with the polyimide film as the substrate obtained in the embodiment is shown in fig. 4, and the biomass organic salt is wrapped outside the conductive particles to isolate the contact with the external environment, so that the silver nanowire can be protected and prevented from being oxidized.

Fig. 5 shows an electromagnetic shielding effectiveness graph of the conductive fabric obtained in this embodiment, when the content of the conductive particles (silver nanowires) is only 0.30 vol%, the electromagnetic shielding effectiveness is 27.7 dB, the electromagnetic shielding effectiveness of the conductive fabric is continuously increased with the increase of the loading capacity of the silver nanowires, and when the loading capacity of the silver nanowires reaches 1.43 vol%, the electromagnetic shielding effectiveness of the fabric is 37.80 dB, which far exceeds the basic commercial standard value, and has certain practical feasibility. When the loading capacity of the silver nanowires reaches 2.57 vol%, the electromagnetic shielding effectiveness can reach 42.05 dB.

The infrared thermal imaging of the waterborne high-conductivity coating obtained in the embodiment can heat the fabric from room temperature to 55 ℃ within 10s under the voltage of 1.5V, so that an option is provided for applying the portable heater to wearable equipment.

Example 2:

step 1: weighing 2.3 g of chitosan, adding 1000 mL of deionized water, adding a succinic acid (0.7 g) solution dissolved in 100 mL of deionized water in advance, and stirring overnight;

step 2: carrying out suction filtration and rotary evaporation on the solution, adding 500 ml of methanol for precipitation, stirring for 12 hours, carrying out suction filtration, and carrying out vacuum drying to obtain biomass succinic acid-chitosan organic salt;

and step 3: dissolving 0.3 g of succinic acid-chitosan organic salt in 50 ml of deionized water, and fully stirring to obtain a biomass succinic acid-chitosan organic salt solution with the weight percent of 0.6;

and 4, step 4: taking 2.57 ml of silver nanowire solution to be placed in 10 ml of biomass succinic acid-chitosan organic salt solution, and stirring for 12 hours to obtain the 30 wt% conductive ink;

and 5: taking a piece of polyimide film (1.5 cm x 2 cm) and taking 1.5 ml of conductive coating by a liquid-transferring gun to drip-coat the polyimide film, drying the polyimide film at a heating table at 60 ℃, and then heating the polyimide film to 180 ℃ for 10 min to obtain a water-based high-conductivity coating taking the polyimide film as a substrate;

step 6: taking a piece of flexible fabric (1.5 cm x 2 cm), respectively carrying out ultrasonic treatment on deionized water and ethanol for 0.5 h, and drying in a vacuum drying oven at 60 ℃;

and 7: soaking the fabric in uniformly dispersed conductive ink for multiple times, extruding out redundant ink, and drying in a drying oven at 60 ℃;

and 8: placing the dried fabric in an oven at 195 deg.C, and maintaining for 20 min;

and step 9: and repeating the steps of dipping and high-temperature crosslinking until the loading amount of the conductive ink on the conductive fabric is 1.50 vol%, so as to obtain the water-based high-conductivity coating taking the fabric as the substrate.

Example 3:

step 1: weighing 2.3 g of chitosan, adding 1000 mL of deionized water, adding a succinic acid (1.08 g) solution dissolved in 200 mL of deionized water in advance, and stirring overnight;

and step 3: weighing 0.3 g of succinic acid-chitosan organic salt, dissolving in 50 ml of deionized water, and fully stirring to obtain 0.6 wt% of biomass succinic acid-chitosan organic salt solution;

and step 9: and repeating the steps of dipping and high-temperature crosslinking until the loading amount of the conductive ink on the conductive fabric is 1.23 vol%, so as to obtain the water-based high-conductivity coating taking the fabric as the substrate.

Claims

1. a preparation method of water-based highly conductive coating, is characterized in that comprising the steps:

Step 1: Add deionized water to chitosan, add pre-dissolved succinic acid solution and stir overnight;

Step 2: the solution is suction-filtered, rotary-evaporated, and precipitated by adding methanol, fully stirred, suction-filtered, and vacuum-dried to obtain succinic acid-chitosan biomass organic salt;

Step 3: dissolving succinic acid-chitosan biomass organic salt in deionized water, and fully stirring to obtain a biomass succinic acid-chitosan organic salt solution;

Step 4: adding the silver nanowire solution to the biomass succinic acid-chitosan salt solution, and fully stirring to obtain a uniform and stable water-based high-conductivity coating;

Step 5: Take a piece of polyimide film, use a pipette to take the above water-based high-conductivity paint and apply it to the polyimide film, dry it on a heating table, and then raise it to a high temperature for a certain period of time to obtain a polyimide film. Film-based water-based highly conductive coating;

Step 6: Take a piece of flexible fabric, ultrasonically clean it with deionized water and ethanol successively, and dry it in a vacuum drying oven;

Step 7: Immerse the fabric in a uniformly dispersed conductive paint, infiltrate and extrude excess paint for several times, and then dry it in a drying oven;

Step 8: place the above-mentioned dried fabric in an oven in a high temperature environment and keep it for a certain period of time;

Step 9: Repeat the above steps of dipping and high-temperature cross-linking until the load of the conductive coating on the conductive fabric reaches a certain value, thereby obtaining a water-based high conductive coating based on the fabric.

2. The preparation method of water-based high-conductivity coating according to claim 1, wherein the biomass organic salt described in the above step 1 is succinic acid-chitosan, and the degree of deacetylation of chitosan is ≥ 75%, molecular weight 310–375 kg/mol.

3 . The method for preparing an aqueous highly conductive coating according to claim 1 , wherein the substrate described in the above step 1 is a high temperature resistant polyimide film or fabric. 4 .

4. The preparation method of the water-based highly conductive coating according to claim 1, wherein the conductive particles described in the above step 1 are silver nanowires, and the silver nanowires have a diameter of 2 nm, a length of 20 μm, and a concentration of 10 mg/ml.

5. The method for preparing an aqueous highly conductive coating according to claim 1, wherein the concentration of the biomass succinic acid-chitosan organic salt solution described in the above step 3 is 0.6 wt%.

6. The preparation method of the water-based high-conductivity coating as claimed in claim 1, wherein: the concentration of conductive particles in the water-based high-conductivity coating described in the above step 4 is 30 wt%-80 wt%.

7. The preparation method of the water-based highly conductive coating as claimed in claim 1, wherein the thickness of the polyimide film described in the above-mentioned step 5 is 0.1 mm, and the volume of the water-based conductive coating obtained by dispensing is 1-2 mm. ml, the temperature was heated to 180°C-195°C and kept for 10-15 min.

8 . The method for preparing an aqueous highly conductive coating according to claim 1 , wherein the thickness of the flexible fabric in the above step 6 is 0.3 mm. 9 .

9 . The method for preparing an aqueous highly conductive coating according to claim 1 , wherein the drying temperature in the above step 7 is heated to 180° C.-220° C. and kept for 10-20 min. 10 .

10. The preparation method of the water-based high-conductivity coating according to claim 1, wherein the dipping described in the above step 7 is to immerse the flexible fabric in the water-based high-conductivity coating, and extrude the excess coating with tweezers, so that the The stated loading reaches 0.30-2.57 vol%.