CN115433511B - Blended aqueous polyurethane-based electromagnetic shielding coating and preparation method thereof - Google Patents
Blended aqueous polyurethane-based electromagnetic shielding coating and preparation method thereof Download PDFInfo
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Abstract
A blended aqueous polyurethane-based electromagnetic shielding coating and a preparation method thereof belong to the technical field of electromagnetic shielding materials. The invention uses camphorsulfonic acid/N-methyl pyrrolidone or camphorsulfonic acid/m-cresol to secondarily dope polyaniline, modifies the chain conformation of the polyaniline, and enhances the ordered structure of polyaniline chains. The nano material carbon nano tube and the conductive polymer polyaniline are compounded together, and the p-p conjugate interaction between the nano material carbon nano tube and the conductive polymer polyaniline forms a continuous conductive network, so that the carrier mobility of the composite filler is increased, the conductive performance is higher than that of a single filler, and the electromagnetic shielding effectiveness is improved. The polyaniline doped with camphorsulfonic acid has good compatibility with the waterborne polyurethane, so that the dispersibility and the compatibility of the polyaniline in the waterborne polyurethane are greatly improved, the agglomeration is reduced, the discontinuous conductive network caused by the agglomeration is avoided, the function of the filler is exerted to the maximum extent, and the performance is further improved.
Description
Technical Field
The invention belongs to the technical field of electromagnetic shielding materials, and particularly relates to a blended waterborne polyurethane-based electromagnetic shielding coating and a preparation method thereof.
Background
Along with the rapid development of electronization and informatization, electromagnetic waves serving as an important carrier for information transmission are permeated into aspects of production and life, and electromagnetic radiation generated by wide use of the electromagnetic waves not only can influence normal work of radio communication and reduce the working performance of precision equipment/instruments, but also can cause damage to human organs and systems to cause dysfunction. Subsequent to noise pollution, air pollution, water pollution, electromagnetic wave pollution has become the fourth most serious pollution threatening human health.
Under the background conditions, the research and development of materials capable of effectively shielding electromagnetic radiation has important significance. Currently, the use of conductive coatings is the most cost effective electromagnetic shielding solution. The electromagnetic shielding conductive coating mainly comprises conductive filler, matrix resin, solvent and the like, can be coated on the surfaces of substrates with various shapes and different materials in a spraying and brushing mode and the like, and can effectively shield electromagnetic waves through the formed conductive curing film.
Electromagnetic shielding conductive coatings can be classified into metallic systems (gold, silver, copper, nickel, etc.) and non-metallic systems (carbon systems) according to the kind of conductive filler. Although the metal conductive paint has good conductivity, the density is large, the price is high, and the metal conductive paint is not suitable for processing. The carbon conductive paint has small density and low price, is expected to become an ideal electromagnetic shielding conductive paint widely applied in the future, but has relatively poor conductivity. Polyaniline is one of typical conductive high-molecular polymers, has low raw material cost, simple and convenient preparation process, easy acquisition and good stability. However, the dispersibility is poor, agglomeration is easy, and the conductivity is still required to be further improved.
In the era of advocating the green environmental protection idea nowadays, the water-type conductive coating is a necessary trend in the future. The traditional electromagnetic shielding paint is mostly solvent type paint, and a large amount of organic solvent volatile matters can be generated in the preparation, production and construction and use processes, so that the electromagnetic shielding paint is harmful to the environment and human bodies. The water paint is environment friendly and has water as solvent or dispersant. The water paint has the outstanding advantages of no toxicity, no harm, no pollution, low cost and the like, and is paid attention to. The aqueous polyurethane has good water dispersibility and is a potential aqueous coating matrix resin. The invention adopts aqueous polyurethane as matrix resin, utilizes multi-wall carbon nano-tubes and polyaniline as conductive fillers to prepare aqueous electromagnetic shielding coating, and forms a conductive network of the multi-wall carbon nano-tubes and the polyaniline inside the coating after spraying and curing to form a film, thus obtaining the electromagnetic shielding coating with high shielding effect.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide the light-weight high-efficiency blended aqueous polyurethane-based electromagnetic shielding coating and the preparation method thereof.
The invention relates to a preparation method of a blended aqueous polyurethane-based electromagnetic shielding coating, which comprises the following steps:
(1) Pretreatment of raw materials: drying the carbon nano tube in vacuum;
(2) Mixing carbon nanotubes and polyaniline, and then placing the mixture in deionized water, and stirring at a high speed to prepare a stirring solution;
(3) Dissolving camphorsulfonic acid in N-methyl pyrrolidone or m-cresol, and performing ultrasonic dissolution to obtain a doping agent;
(4) Pretreatment 1: filtering and drying the stirring solution obtained in the step (2) to obtain carbon nano tube/polyaniline powder; then placing the powder in ammonia water, stirring, filtering, washing and drying to obtain a pretreated substance 1;
(5) Pretreatment 2: placing the pretreated matter 1 obtained in the step (4) into a dispersion liquid, adding the doping agent of the step (3) under stirring, then stirring and reacting for a period of time, filtering, washing and drying to obtain a carbon nano tube-polyaniline mixture; then the carbon nano tube-polyaniline mixture and deionized water are mixed according to a certain mass ratio to prepare a carbon nano tube-polyaniline mixed solution;
(6) Adding a dispersing agent into the carbon nano tube-polyaniline mixed solution obtained in the step (5), and uniformly stirring and mixing to obtain a component A;
(7) Adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly stirring and mixing to obtain a component B;
(8) The component A and the component B react for a period of time under stirring, and the doped water-based electromagnetic shielding coating is obtained after static defoaming.
Specifically, in the step (1), the vacuum drying time is 24-36 hours.
Specifically, in the step (2), the mass ratio of the carbon nano tube to the polyaniline is 0.25-4: 1, the stirring speed is 4000-4200 r/min, and the stirring time is 3-5 h.
Specifically, in the step (3), the concentration of camphorsulfonic acid is 10-20 mg/mL;
specifically, in the step (4), the concentration of ammonia water is 0.1M, the stirring speed is 200-500 r/min, and the stirring time is 24-48 h;
specifically, in the step (5), the dispersion liquid is N-methyl pyrrolidone or m-cresol; in deionized water, the mass fraction of the carbon nano tube-polyaniline mixture is 2-5%, the stirring rate of adding the doping agent is 500-1000 r/min, and the stirring time is 15-30 min; the speed of the subsequent stirring reaction is 200-500 r/min, and the stirring reaction time is 24-48 h; the dosage ratio of the pretreatment 1 to the doping agent is 0.02-0.2 g:1mL of
Specifically, in the step (6), the mass fraction of the dispersing agent accounts for 0.3-0.8 wt% of the component A, and the stirring speed is 500-1000 r/min.
Specifically, in the step (7), the mass percentages of the aqueous polyurethane emulsion, the defoamer, the wetting agent and the thickener are respectively 82 to 92 percent, 0.86 to 0.95 percent, 1.0 to 1.1 percent and 5.95 to 16.14 percent according to the total mass percentage of 100 percent; the defoaming agent is at least one of Tech-3825, tego-825 and BYK-023, the wetting agent is at least one of Levelol W-469, tech-2845, tech-278 and Michaelis L-77, the thickening agent is at least one of AH-350D, AH-zcj and Rheosis PU1190, and the stirring rate is 500-1000 r/min.
Specifically, in the step (8), the volume ratio of the component A to the component B is 0.3-2: 1, stirring reaction speed is 500-1000 r/min, and stirring reaction time is 0.5-2 h.
Compared with the prior art, the invention has the following advantages:
the invention uses camphorsulfonic acid/N-methyl pyrrolidone or camphorsulfonic acid/m-cresol to secondarily dope polyaniline, modifies the chain conformation of the polyaniline, and enhances the ordered structure of polyaniline chains. The nano material carbon nano tube and the conductive polymer polyaniline are compounded together, and the p-p conjugate interaction between the nano material carbon nano tube and the conductive polymer polyaniline forms a continuous conductive network, so that the carrier mobility of the composite filler is increased, the conductive performance is higher than that of a single filler, and the electromagnetic shielding effectiveness is improved. The polyaniline doped with camphorsulfonic acid has good compatibility with the waterborne polyurethane, so that the dispersibility and the compatibility of the polyaniline in the waterborne polyurethane are greatly improved, the agglomeration is reduced, the discontinuous conductive network caused by the agglomeration is avoided, the function of the filler is exerted to the maximum extent, and the performance is further improved.
Drawings
Fig. 1: infrared spectra (IR) of the products of example 1 and example 3;
fig. 2: electromagnetic Shielding Effectiveness (SE) diagram of the product of example 1;
fig. 3: normalized specific electromagnetic shielding effectiveness (SSE) for the product of example 1;
as shown in FIG. 1, 1029cm -1 The peak at which comes from camphorsulfonic acid, which is attributed to SO 3 -a group, proving that blending has been successful. At 3320cm -1 N-H stretching vibration peak of hydrogen bonding, 2910cm -1 And 2850cm -1 respectively-CH 3 -CH 2 C-H stretching vibration absorption peak. 1700cm -1 At 1530cm is the ester carbonyl absorption peak in the urethane linkage -1 Is C-N bond telescopic vibration absorption peak, 1236cm -1 Asymmetric stretching vibration peak of carbamate bond of 1090cm -1 Is the-C-O-C-telescopic vibration absorption peak.
As shown in fig. 2, the frequency (GHz) is the X-band (8.2 to 12.4 GHz); the graph is plotted with shielding effectiveness (dB) on the ordinate. Sample size (22.9 x 10.2 x 0.04 mm) 3 ). The numbers 1, 2, 3 represent the total shielding effectiveness value (SE T ) Absorption-induced shielding effectiveness value (SE A ) Reflection-generated shielding effectiveness value (SE R ) Wherein SE is A The absorption produces a shielding effectiveness value that is a major contribution to the total shielding effectiveness value. The three have the following relations:
SE T ＝SE R +SE A
the electromagnetic shielding performance related S parameters S11, S12, S21, S22 can be obtained by a network vector analyzer, and the corresponding reflection coefficient (R), absorption coefficient (a) and transmission coefficient (T) can be calculated by these parameters, and the relationship between them is as follows:
R＝|S11| 2 ＝|S22| 2
T＝|S12| 2 ＝|S21| 2
the reflection coefficient (R), absorption coefficient (a) and transmission coefficient (T) have the following relationship: r+a+t=1, typically SE A And SE R The conversion formula between R and T coefficients is:
SE R ＝-10lg(1-R)
the figure illustrates that the polyaniline secondarily doped with camphorsulfonic acid/N-methylpyrrolidone or camphorsulfonic acid/m-cresol is compounded with the multi-walled carbon nanotubes to form a good conductive network in the aqueous polyurethane of the matrix resin, so that the coating has good electromagnetic shielding effectiveness in the X-band. The blended aqueous polyurethane-based electromagnetic shielding coating is an electromagnetic shielding coating mainly based on absorption.
As shown in FIG. 3, the numbers 1, 2, 3 respectively represent normalized total specific electromagnetic shielding effectiveness values (SSE T ) Normalized absorption-generated specific electromagnetic shielding effectiveness value (SSE) A ) Normalized reflection-generated shielding effectiveness value (SSE) R ) The three have the following relations:
SSE T ＝SSE R +SSE A
the thickness and density of the coating are different from each other, and the electromagnetic shielding performance of the coating is expressed by a normalized specific electromagnetic shielding effectiveness value (SSE) by the calculation formula
Wherein SE: the electromagnetic shielding effectiveness value, expressed in dB,
ρ: representation ofDensity in g/cm 3 ，
d: the thickness of the sample is expressed in cm.
The normalized total specific electromagnetic shielding effectiveness value can be used for viewing the magnitude of the unit electromagnetic shielding effectiveness value, and the blended aqueous polyurethane-based electromagnetic shielding coating is mainly an electromagnetic shielding coating based on absorption. The figure illustrates that the water-based electromagnetic shielding coating is prepared by using the multi-wall carbon nano tube and polyaniline as conductive fillers, and a conductive network of the multi-wall carbon nano tube and the polyaniline is formed inside the coating after spraying and curing to form a film, so that the electromagnetic shielding coating with high shielding effect is obtained.
Detailed Description
The invention discloses a blended waterborne polyurethane-based electromagnetic shielding coating and a preparation method thereof. Is prepared from the mixture of carbon nano tube and polyaniline, aqueous polyurethane emulsion and other assistants through stirring at ordinary temp. The high-conductivity composite filler carbon nano tube-polyaniline is combined with the environment-friendly matrix resin aqueous polyurethane, so that the aqueous polyurethane is utilized to endow the electromagnetic shielding coating with good mechanical property, excellent compatibility and easy processing property; on the other hand, the composite filler is utilized to endow the coating with excellent conductivity and electromagnetic shielding performance. The coating has good physical and chemical properties, and the practicality of light weight, low cost and easy processing is realized. Wherein the component A is formed by adding a dispersing agent into a carbon nano tube-polyaniline mixed solution; the component B consists of aqueous polyurethane emulsion, a thickening agent, a defoaming agent and a wetting agent.
The following is further illustrated by four specific examples:
example 1:
1. preparation of a stirring solution: the multiwall carbon nanotubes (technical grade) were dried under vacuum for 36h. Mixing dry multi-wall carbon nano-tubes (industrial grade) with polyaniline according to a mass ratio of 4:1 (mass is 8g and 2g respectively) are mixed and placed in deionized water (288.5 mL), and the mixture is stirred at high speed for 4h at room temperature and at the rotation speed of 4200r/min, so as to prepare a stirring liquid.
2. Preparation of the dopant: camphorsulfonic acid is dissolved in N-methyl pyrrolidone, and dissolved by ultrasonic to prepare 10mg/mL camphorsulfonic acid/N-methyl pyrrolidone solution.
3. Pretreatment 1: the stirring solution obtained in the step 1 is filtered and dried to obtain carbon nano tube/polyaniline powder (9.9 g), and the carbon nano tube/polyaniline powder is placed in 0.1M ammonia water, and is stirred (the rotating speed is 300r/min,48 h), filtered, washed (water is washed 3 times and then alcohol is washed 3 times), and dried to obtain a pretreated material 1 (9.52 g).
4. Pretreatment 2: placing the pretreated matter 1 obtained in the step 3 into N-methylpyrrolidone (186 mL), stirring at a rotating speed of (1000 r/min,20 min), dropwise adding a doping agent (64 mL) while stirring, regulating the rotating speed to 300r/min after dropwise adding, stirring for 24h, filtering, washing (3 times of water washing and 3 times of alcohol washing), and drying to obtain a carbon nano tube-polyaniline mixture (9.76 g); the carbon nanotube-polyaniline mixture (3.3 g) and deionized water (96.7 g) were then mixed under stirring to prepare a carbon nanotube-polyaniline mixture.
5. Preparation of component A: adding N-methyl pyrrolidone into the mixed solution obtained in the step 4, and uniformly mixing at a stirring speed of 500r/min to obtain a component A; in the component A, the mass fraction of the carbon nano tube-polyaniline mixed solution is 99.5wt%, and the mass fraction of the dispersing agent is 0.5wt%.
6. Preparation of component B: adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly mixing at a stirring speed of 500r/min to obtain a component B; in the component B, the mass fraction of the aqueous polyurethane emulsion is 82wt%, the mass fraction of the defoamer is 0.86wt%, the mass fraction of the wetting agent is 1.0wt%, and the mass fraction of the thickener is 16.14wt%. The defoamer is Tech-3825, the wetting agent is level W-469, and the thickener is AH-zcj.
7. Component A and component B are mixed according to the following formula 2:1, mixing for 1h at a stirring speed of 500r/min, and standing for defoaming until no bubbles are generated in the system, thereby obtaining the doped water-based electromagnetic shielding coating.
8. And (3) spraying the product obtained after defoaming in the step (7) on an ABS plastic substrate by using a spraying process, and curing for 6 hours at a constant temperature of 50 ℃, wherein the performance is shown in Table 1.
Example 2:
1. preparation of a stirring solution: the multiwall carbon nanotubes (technical grade) were dried under vacuum for 36h. Mixing dry multi-wall carbon nano-tubes (industrial grade) with polyaniline according to a mass ratio of 3:2 (mass respectively 6g and 4 g) are mixed and placed in deionized water (288.5 mL), and the mixture is stirred at a high speed for 4h at room temperature, and the rotating speed is 4100r/min, so as to prepare a stirring liquid.
2. Preparation of the dopant: camphorsulfonic acid is dissolved in N-methyl pyrrolidone, and dissolved by ultrasonic to prepare 10mg/mL camphorsulfonic acid/N-methyl pyrrolidone solution.
3. Pretreatment 1: the stirring solution obtained in the step 1 is filtered and dried to obtain carbon nano tube/polyaniline powder (9.8 g), and the carbon nano tube/polyaniline powder is placed in 0.1M ammonia water, stirred (the rotation speed is 300r/min,48 h), filtered and washed (water washing is carried out 3 times and then alcohol washing is carried out 3 times), so as to obtain a pretreated material 1 (9.04 g).
4. Pretreatment 2: placing the pretreated matter 1 obtained in the step 3 into N-methylpyrrolidone (372 mL), stirring (the rotation speed is 500 r/min), stirring for 20 minutes, dropwise adding a doping agent (128 mL) while stirring, adjusting the rotation speed to 300r/min after dropwise adding, stirring for 24 hours, filtering, washing, drying (3 times of water washing and 3 times of alcohol washing), and obtaining a carbon nano tube-polyaniline mixture (9.53 g); the carbon nanotube-polyaniline mixture (3.3 g) and deionized water (96.7 g) were then mixed under stirring to prepare a carbon nanotube-polyaniline mixture.
5. Preparation of component A: adding N-methyl pyrrolidone into the mixed solution obtained in the step 4, and uniformly mixing at a stirring speed of 500r/min to obtain a component A; in the component A, the mass fraction of the carbon nano tube-polyaniline mixed solution is 99.5wt%, and the mass fraction of the dispersing agent is 0.5wt%.
6. Preparation of component B: adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly mixing at a stirring speed of 600r/min to obtain a component B; in the component B, the mass fraction of the aqueous polyurethane emulsion is 85wt%, the mass fraction of the defoamer is 0.87wt%, the mass fraction of the wetting agent is 1.0wt%, and the mass fraction of the thickener is 13.13wt%. The defoamer is Tech-3825, the wetting agent is level W-469, and the thickener is AH-zcj.
7. Component A and component B were mixed according to 1.5:1, mixing for 0.5h at a stirring speed of 600r/min, and standing for defoaming until no bubbles are generated in the system, thereby obtaining the doped water-based electromagnetic shielding coating.
8. And (3) spraying the product obtained after defoaming in the step (7) on an ABS plastic substrate by using a spraying process, and curing for 6 hours at a constant temperature of 50 ℃, wherein the performance is shown in Table 1.
Example 3:
1. preparation of a stirring solution: the multiwall carbon nanotubes (technical grade) were dried under vacuum for 36h. Mixing the dried multi-wall carbon nano tube (industrial grade) with polyaniline according to a mass ratio of 2:3 (mass respectively 4g and 6 g) are mixed and placed in deionized water (288.5 mL), and the mixture is stirred at high speed for 4h at room temperature, and the rotating speed is 4000r/min, so as to prepare a stirring liquid.
2. Preparation of the dopant: camphorsulfonic acid was dissolved in m-cresol, and dissolved by ultrasound to prepare a camphorsulfonic acid/m-cresol solution of 10 mg/mL.
3. Pretreatment 1: the stirring solution obtained in the step 1 is filtered and dried to obtain carbon nano tube/polyaniline powder (9.9 g), and the carbon nano tube/polyaniline powder is placed in 0.1M ammonia water, stirred (the rotation speed is 300r/min,48 h), filtered and washed (water washing is carried out 3 times and then alcohol washing is carried out 3 times), so as to obtain a pretreated material 1 (8.56 g).
4. Pretreatment 2: placing the pretreated substance 1 obtained in the step 3 into m-cresol (183 mL), stirring (the rotating speed is 1000r/min and 20 min), dropwise adding a doping agent (192 mL) while stirring, adjusting the rotating speed to 300r/min after dropwise adding, and stirring for 36h; filtering, washing and drying (3 times of water washing and 3 times of alcohol washing) to obtain a carbon nano tube-polyaniline mixture (9.29 g); the carbon nanotube-polyaniline mixture (3.3 g) and deionized water (96.7 g) were then mixed under stirring to prepare a carbon nanotube-polyaniline mixture.
5. Preparation of component A: adding m-cresol into the mixed solution obtained in the step 4, and uniformly mixing at a stirring speed of 500r/min to obtain a component A; in the component A, the mass fraction of the carbon nano tube-polyaniline mixed solution is 99.5wt%, and the mass fraction of the dispersing agent is 0.5wt%.
6. Preparation of component B: adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly mixing at a stirring speed of 600r/min to obtain a component B; in the component B, the mass fraction of the aqueous polyurethane emulsion is 90wt%, the mass fraction of the defoamer is 0.93wt%, the mass fraction of the wetting agent is 1.0wt%, and the mass fraction of the thickener is 8.07wt%. The defoamer is Tech-3825, the wetting agent is level W-469, and the thickener is AH-zcj.
7. Component A and component B were mixed according to 0.7:1, mixing for 1.0h at a stirring speed of 800r/min, and standing for defoaming until no bubbles are generated in the system, thereby obtaining the doped water-based electromagnetic shielding coating.
8. And (3) spraying the product obtained after defoaming in the step (7) on an ABS plastic substrate by using a spraying process, and curing for 6 hours at a constant temperature of 50 ℃, wherein the performance is shown in Table 1.
Example 4:
1. preparation of a stirring solution: the multiwall carbon nanotubes (technical grade) were dried under vacuum for 36h. Mixing the dried multi-wall carbon nano tube (industrial grade) with polyaniline according to a mass ratio of 1:4 (mass respectively 2g and 8 g) are mixed and placed in deionized water (288.5 mL), and the mixture is stirred at high speed for 4h at room temperature, and the rotating speed is 4000r/min, so as to prepare a stirring liquid.
2. Preparation of the dopant: camphorsulfonic acid was dissolved in m-cresol, and dissolved by ultrasound to prepare a camphorsulfonic acid/m-cresol solution of 10 mg/mL.
3. Pretreatment 1: the stirring solution obtained in the step 1 is filtered and dried to obtain carbon nano tube/polyaniline powder (9.8 g), and the carbon nano tube/polyaniline powder is placed in 0.1M ammonia water, stirred (the rotation speed is 300r/min,48 h), filtered and washed (water washing is carried out 3 times and then alcohol washing is carried out 3 times), so as to obtain a pretreated material 1 (8.08 g).
4. Pretreatment 2: placing the pretreated substance 1 obtained in the step 3 into m-cresol (244 mL), stirring (the rotating speed is 1000r/min and 20 min), dropwise adding a doping agent (256 mL) while stirring, adjusting the rotating speed to 300r/min after dropwise adding, and stirring for 48h; filtering, washing and drying (3 times of water washing and 3 times of alcohol washing) to obtain a carbon nano tube-polyaniline mixture (9.05 g); the carbon nanotube-polyaniline mixture (3.3 g) and deionized water (96.7 g) were then mixed under stirring to prepare a carbon nanotube-polyaniline mixture.
5. Preparation of component A: adding m-cresol into the mixed solution obtained in the step 4, and uniformly mixing at a stirring speed of 500r/min to obtain a component A; in the component A, the mass fraction of the carbon nano tube-polyaniline mixed solution is 99.5wt%, and the mass fraction of the dispersing agent is 0.5wt%.
6. Preparation of component B: adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly mixing at a stirring speed of 600r/min to obtain a component B; in the component B, the mass fraction of the aqueous polyurethane emulsion is 92wt%, the mass fraction of the defoamer is 0.95wt%, the mass fraction of the wetting agent is 1.1wt%, and the mass fraction of the thickener is 5.95wt%. The defoamer is Tech-3825, the wetting agent is level W-469, and the thickener is AH-zcj.
7. Component A and component B were mixed according to 0.3:1, mixing for 0.5h at a stirring speed of 1000r/min, and standing for defoaming until no bubbles are generated in the system, thereby obtaining the doped water-based electromagnetic shielding coating.
8. And (3) spraying the product obtained after defoaming in the step (7) on an ABS plastic substrate by using a spraying process, and curing for 6 hours at a constant temperature of 50 ℃, wherein the performance is shown in Table 1.
Table 1: performance data for the products of the examples
| Example 1 | Example 2 | Example 3 | Example 4 | |
| Impact-resistant Kg.cm (front-back) | 30-30 | 40-40 | 50-50 | 50-50 |
| Adhesion force | Level 0 | Level 0 | Level 0 | Level 0 |
As shown in Table 1, the adhesive force of the blended aqueous polyurethane-based electromagnetic shielding coating reaches the highest level 0, and the blended aqueous polyurethane-based electromagnetic shielding coating has good performance in the aspect of impact resistance, namely forward impact resistance and recoil resistance. The coatings prepared from the coating all show excellent mechanical properties.
Claims (10)
1. A preparation method of a blended aqueous polyurethane-based electromagnetic shielding coating comprises the following steps:
(1) Pretreatment of raw materials: drying the carbon nano tube in vacuum;
(2) Mixing carbon nanotubes and polyaniline, and then placing the mixture in deionized water, and stirring at a high speed to prepare a stirring solution; the mass ratio of the carbon nano tube to the polyaniline is 0.25-4: 1, a step of;
(3) Dissolving camphorsulfonic acid in N-methyl pyrrolidone or m-cresol, and performing ultrasonic dissolution to obtain a doping agent;
(4) Pretreatment 1: filtering and drying the stirring solution obtained in the step (2) to obtain carbon nano tube/polyaniline powder; then placing the powder in ammonia water, stirring, filtering, washing and drying to obtain a pretreated substance 1;
(5) Pretreatment 2: placing the pretreated matter 1 obtained in the step (4) into a dispersion liquid, adding the doping agent of the step (3) under stirring, then stirring and reacting for a period of time, filtering, washing and drying to obtain a carbon nano tube-polyaniline mixture; then the carbon nano tube-polyaniline mixture and deionized water are mixed according to a certain mass ratio to prepare a carbon nano tube-polyaniline mixed solution; the dosage ratio of the pretreatment 1 to the dopant is 0.02-0.2 g:1mL;
(6) Adding a dispersing agent into the carbon nano tube-polyaniline mixed solution obtained in the step (5), and uniformly stirring and mixing to obtain a component A;
(7) Adding a defoaming agent, a wetting agent and a thickening agent into the aqueous polyurethane emulsion, and uniformly stirring and mixing to obtain a component B;
(8) Reacting the component A with the component B for a period of time under stirring, and standing for defoaming to obtain the doped water-based electromagnetic shielding coating; the volume ratio of the component A to the component B is 0.3-2: 1.
2. the method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (1), the vacuum drying time is 24-36 hours.
3. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (2), the stirring speed is 4000-4200 r/min, and the stirring time is 3-5 h.
4. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (3), the concentration of camphorsulfonic acid is 10-20 mg/mL.
5. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (4), the concentration of ammonia water is 0.1M, the stirring speed is 200-500 r/min, and the stirring time is 24-48 h.
6. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (5), the dispersion liquid is N-methyl pyrrolidone or m-cresol; in deionized water, the mass fraction of the carbon nano tube-polyaniline mixture is 2-5%, the stirring rate of adding the doping agent is 500-1000 r/min, and the stirring time is 15-30 min; the speed of the subsequent stirring reaction is 200-500 r/min, and the stirring reaction time is 24-48 h.
7. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: specifically, in the step (6), the mass fraction of the dispersing agent accounts for 0.3-0.8wt% of the component A, and the stirring speed is 500-1000 r/min.
8. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (7), the mass percentages of the aqueous polyurethane emulsion, the defoamer, the wetting agent and the thickener are respectively 82-92%, 0.86-0.95%, 1.0-1.1% and 5.95-16.14% according to the total mass percentage of 100%; the defoaming agent is at least one of Tech-3825, tego-825 and BYK-023, the wetting agent is at least one of Levelol W-469, tech-2845, tech-278 and Michael L-77, the thickening agent is at least one of AH-350D, AH-zcj and Rheosis PU1190, and the stirring rate is 500-1000 r/min.
9. The method for preparing the blended aqueous polyurethane-based electromagnetic shielding coating according to claim 1, which is characterized in that: in the step (8), the stirring reaction speed is 500-1000 r/min, and the stirring reaction time is 0.5-2 h.
10. A blended aqueous polyurethane-based electromagnetic shielding coating is characterized in that: is prepared by the method of any one of claims 1-9.
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| CN1789338A (en) * | 2004-12-15 | 2006-06-21 | 中国科学院化学研究所 | Electricity conductive polyaniline carbon nanotube combined electromagnetic shielding composite material and its production method |
| KR20190060042A (en) * | 2017-11-24 | 2019-06-03 | 주식회사 빅스 | Conductive water-dispersible polyurethane resin composition for surface coating of emi gasket material and its manufacturing process |
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| TWI449763B (en) * | 2012-04-30 | 2014-08-21 | Eternal Materials Co Ltd | Conductive coating composition |
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| DE102018115503A1 (en) * | 2018-06-27 | 2020-01-02 | Carl Freudenberg Kg | Shielding composition for electromagnetic radiation |
| CN109384919A (en) * | 2018-11-07 | 2019-02-26 | 江苏维特金属防腐科技有限公司 | Electrically conductive polyaniline carbon nanotube nucleocapsid hybrid composite material, preparation method and applications |
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| CN1789338A (en) * | 2004-12-15 | 2006-06-21 | 中国科学院化学研究所 | Electricity conductive polyaniline carbon nanotube combined electromagnetic shielding composite material and its production method |
| KR20190060042A (en) * | 2017-11-24 | 2019-06-03 | 주식회사 빅스 | Conductive water-dispersible polyurethane resin composition for surface coating of emi gasket material and its manufacturing process |
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