Wave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces and preparation method thereof

Abstract

The invention discloses a wave-absorbing microcapsule suitable for a transparent water-based paint on a wood surface and a preparation method thereof. The microcapsule comprises the following raw materials in parts by weight: 15 to 30 parts by weight of urea, 30 to 50 parts by weight of a formaldehyde solution, 10 to 20 parts by weight of triethanolamine, 0.05 to 0.5 parts by weight of carbonyl iron, 0.05 to 0.5 parts by weight of carbon black, 0.005 to 2 parts by weight of sodium dodecylbenzenesulfonate, and 5 to 20 parts by weight of distilled water. The wave-absorbing microcapsule suitable for the transparent water-based paint on a wood surface provided by the invention has wave-absorbing performance and can be applied to the water-based paint to improve the mechanical properties and electromagnetic radiation absorption performance of the water-based paint on the wood surface. After the transparent water-based paint containing the wave-absorbing microcapsules is applied to the wood surface, the coating on the wood surface can effectively absorb electromagnetic radiation in the environment, thereby reducing the impact of electromagnetic radiation on the environment and human body.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and in particular to carbonyl iron / carbon black microcapsules suitable for transparent water-based coatings with both wave-absorbing and crack-prevention properties on wood surfaces, and a preparation method thereof, referred to as microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces and a preparation method thereof. Background Art

[0002] With the advancement of science and technology, humanity has entered the information age. Electromagnetic pollution has become the fourth major public health hazard. Among various traditional absorbing materials, carbonyl iron has been widely used due to its high magnetic permeability, high saturation magnetization, high Curie temperature, excellent absorption performance, and wide absorption bandwidth. It is currently a commonly used absorber. However, since a single medium in everyday life cannot simultaneously meet the requirements of high matching and strong absorption, multi-component absorbers have become an important solution to this problem. Composite absorbers composed of carbon black and carbonyl iron powder have the advantages of low cost and wide availability. They have attracted considerable attention in multi-component absorber research both domestically and internationally and are of great significance for reducing electromagnetic radiation in space. The application of absorbing microcapsules in water-based paints can improve the absorption performance of the paint film. However, since carbonyl iron and carbon black are both dark in color, adding even small amounts can affect the transparency of water-based paints. Therefore, the amount of carbonyl iron and carbon black added to the microcapsules must be strictly controlled to ensure that they meet the required absorption requirements for environmental electromagnetic radiation without affecting the transparency of the water-based paint.

[0003] In summary, the increasing number of electronic and electrical devices currently used in production and life has led to increasingly serious impacts of electromagnetic radiation on the environment and human body. If a microcapsule with absorbing properties can be provided that can be used in a transparent water-based paint on the surface of wood materials, then after the wood material is coated with the transparent water-based paint containing absorbing microcapsules, it can effectively absorb electromagnetic radiation in the environment and reduce the impact of electromagnetic radiation on the environment and human body. Summary of the Invention

[0004] The purpose of the present invention is to address the increasingly serious problem of electromagnetic radiation affecting the environment and human body due to the increasing number of electronic and electrical equipment used in current production and life. The present invention provides a microwave-absorbing microcapsule suitable for transparent water-based paint on wood surface and a preparation method. The microcapsule has microwave-absorbing properties and can be applied to water-based paint to improve the mechanical properties and electromagnetic radiation absorption performance of the water-based paint on wood surface. After the transparent water-based paint containing the microwave-absorbing microcapsules is applied to the wood surface, the coating on the wood surface can effectively absorb electromagnetic radiation in the environment, reducing the impact of electromagnetic radiation on the environment and human body.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] The microwave-absorbing microcapsules suitable for transparent water-based paint on wood surface include the following raw materials in parts by weight:

[0007] 15-30 parts by weight of urea, 30-50 parts by weight of formaldehyde aqueous solution, 10-20 parts by weight of triethanolamine, 0.05-0.5 parts by weight of carbonyl iron, 0.05-0.5 parts by weight of carbon black, 0.005-2 parts by weight of sodium dodecylbenzenesulfonate and 5-20 parts by weight of distilled water.

[0008] As a preferred embodiment of the present invention, the following raw materials are included in parts by weight:

[0009] 20-27 parts by weight of urea, 34-44 parts by weight of 37% formaldehyde aqueous solution, 13-19 parts by weight of triethanolamine, 0.1-0.4 parts by weight of carbonyl iron, 0.08-0.3 parts by weight of carbon black, 0.1-1.5 parts by weight of sodium dodecylbenzenesulfonate and 8-18 parts by weight of distilled water.

[0010] As a further improved technical solution of the present invention, the carbonyl iron is in the form of flakes with a thickness of 10 microns and a particle size of 80 to 100 microns; the carbon black is in the form of needles with a diameter of 30 to 50 microns and a length of 3 to 5 centimeters.

[0011] In order to achieve the above technical objectives, another technical solution adopted by the present invention is:

[0012] A method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces comprises the following steps:

[0013] (1) Mix urea and formaldehyde aqueous solution, stir thoroughly until the urea is dissolved, and adjust the pH with triethanolamine. The resulting solution is the wall material solution;

[0014] (2) adding sodium dodecylbenzenesulfonate to distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0015] (3) adding carbonyl iron and carbon black to an aqueous solution of sodium dodecylbenzenesulfonate, and slowly stirring in a water bath at a certain temperature until the compound is completely and evenly dispersed; then heating to a certain temperature and continuing to stir; ultrasonically subjecting the stirred solution to obtain a stable core material emulsion;

[0016] (4) The core material emulsion after ultrasonic treatment is placed at room temperature for a period of time and then placed in a water bath for stirring; the wall material solution is added dropwise to the core material emulsion using a separatory funnel, and the stirring is continued, and the lemon water solution is added dropwise; after the reaction is completed, the temperature is raised to a preset temperature, the stirring speed is reduced, and the reaction is continued to obtain a microcapsule solution; after the microcapsule solution is cooled to room temperature, it is filtered and dried, and the obtained powder is the wave-absorbing microcapsule suitable for transparent water-based coatings on wood surfaces.

[0017] As a further improved technical solution of the present invention, in step (1), urea and 37% formaldehyde aqueous solution are added to a three-necked flask, stirred thoroughly until the urea is dissolved, and the pH is adjusted to 8.5 with triethanolamine. The resulting solution is the wall material solution.

[0018] As a further improved technical solution of the present invention, in step (3), carbonyl iron and carbon black are added to an aqueous solution of sodium dodecylbenzenesulfonate, and slowly stirred in a 50°C water bath until the compound is completely and evenly dispersed; then the temperature is raised to 65°C and stirring is continued for 20 minutes; the stirred solution is placed in an ultrasonic emulsifier and ultrasonicated for 5 minutes to obtain a stable core material emulsion.

[0019] As a further improved technical solution of the present invention, in step (4), the core material emulsion after ultrasonication is placed at room temperature for a period of time and then placed in a 35°C water bath for stirring; the wall material solution is added dropwise to the core material solution using a separatory funnel, and the stirring is continued using a mechanical stirrer, and an 8% lemon water solution is added dropwise to adjust the pH of the solution to 2.5, and the reaction is carried out for 1 hour; after the reaction is completed, the temperature is raised to 68°C, the speed is reduced to 250 r / min, and the reaction is continued for 30 minutes to obtain a microcapsule solution; after the microcapsule solution is cooled to room temperature, it is filtered with a vacuum pump, and the powder obtained after drying in an oven is the water-based coating wave-absorbing microcapsule for the wood material surface of the present invention.

[0020] As a further improved technical solution of the present invention, in step (4), the stirring speed of the mechanical stirrer is 500 r / min, and the emulsification time is 20 min.

[0021] As a further improved technical solution of the present invention, in step (4), the drying temperature is 35° C. and the drying time is 3-5 h.

[0022] The beneficial effects of the present invention are:

[0023] The composite absorber composed of carbonyl iron and carbon black can simultaneously meet the characteristics of high matching and strong absorption, has excellent absorption performance and a wide absorption frequency band, and has the advantages of low price and wide source. Since the selected flake carbonyl iron and needle-shaped carbon black can form a strong network structure in the microcapsule, it can enhance the toughness of the water-based paint film and prevent the water-based paint film from cracking. At the same time, the addition amount of carbonyl iron and carbon black is precisely controlled to achieve the absorption of electromagnetic radiation in the environment without affecting the transparency of the water-based paint film.

[0024] The present invention uses urea, 37% formaldehyde aqueous solution and triethanolamine as capsule wall raw materials, and carbonyl iron and carbon black as capsule cores to prepare carbonyl iron / carbon black microcapsules. The microcapsule technology is used to synthesize a material with wave-absorbing function. When applied to water-based coatings, the surface coating of the wood material can have low gloss and wear resistance, impact resistance, electromagnetic radiation absorption and anti-cracking properties.

[0025] The present invention mainly uses the experiment of modifying water-based coating with microcapsules to make the coating have low gloss and abrasion resistance, impact resistance, wave absorption performance and anti-cracking performance. The microcapsules of the present invention are added in an amount of 5% to a water-based coating on a wood material surface. After the microcapsules are added, the glossiness of the paint film is tested using a gloss meter according to GB / T 4893.6-2013, and the glossiness of the coating film is matte. According to the national standard GB / T 4893.8-2013, the abrasion resistance of the coating film is tested using a paint film abrasion meter, and the abrasion resistance is level 1 (abrasion revolution number of 5000 revolutions). According to GB / T 4893.9-2013, the impact resistance of the paint film is measured using an impact tester, and the impact resistance height is 50 cm. The electromagnetic parameters of the absorbing material at 2-20 GHz are tested using an Agilent E8363C vector network analyzer, and the theoretical reflection loss value of the microcapsules is measured to be between -13 and -20 dB depending on the content of each component constituting the microcapsule. According to GB / T33569-2017, the anti-cracking performance of the paint film is measured using an artificial aging test, and the paint film does not crack. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are further described below with reference to the accompanying drawings:

[0028] Example 1:

[0029] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0030] (1) Add 30 g of urea and 45 g of 37% formaldehyde aqueous solution into a three-necked flask, stir thoroughly until the urea is dissolved, and adjust the pH to 8.5 with 15 g of triethanolamine. The resulting solution is the wall material solution;

[0031] (2) adding 1 g of sodium dodecylbenzenesulfonate to 8.3 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0032] (3) Add 0.4 g of carbonyl iron and 0.3 g of carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a 50°C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65°C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0033] (4) The core material emulsion after ultrasonication was placed at room temperature for a period of time and then placed in a water bath at 35°C and stirred slowly; the wall material solution was added dropwise to the core material solution using a separatory funnel, and the stirring was continued using a mechanical stirrer with a stirring speed of 500 r / min and an emulsification time of 20 min; 8% lemon water solution was added dropwise to adjust the pH of the solution to about 2.5 and the reaction was continued for 1 h; after the reaction was completed, the temperature was raised to 68°C, the speed was reduced to 250 r / min, and the reaction was continued for 30 min to obtain a microcapsule solution; after the microcapsule solution was cooled to room temperature, it was filtered with a vacuum pump and dried in an oven at 35°C for 4 hours. The powder obtained was the required wave-absorbing microcapsules.

[0034] Example 2:

[0035] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0036] (1) Add 25 g of urea and 50 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 14 g of triethanolamine. The resulting solution is the wall material solution.

[0037] (2) adding 0.005 g of sodium dodecylbenzenesulfonate to 10.295 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0038] (3) Add 0.3 g of carbonyl iron and 0.4 g of carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a 50°C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65°C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0039] (4) Place the ultrasonic core material emulsion at room temperature for a period of time, then place it in a 35°C water bath and stir slowly. Use a separatory funnel to add the wall material solution dropwise to the core material solution, and continue stirring with a mechanical stirrer at a stirring speed of 500r / min and an emulsification time of 20min; add 8% lemon water solution dropwise to adjust the pH of the solution to about 2.5, and react for 1h; after the reaction is completed, heat it to 68°C, reduce the speed to 250r / min, and continue to react for 30min to obtain a microcapsule solution. After cooling the microcapsule solution to room temperature, filter it with a vacuum pump, and dry it in a 35°C oven for 3 hours. The resulting powder is the desired absorbing microcapsule.

[0040] Example 3:

[0041] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0042] (1) Add 28 g of urea and 45.1 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 20 g of triethanolamine. The resulting solution is the wall material solution.

[0043] (2) adding 1.5 g of sodium dodecylbenzenesulfonate to 5 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0044] (3) Add 0.35 g of carbonyl iron and 0.05 g of carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a 50 °C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65 °C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0045] (4) The core material emulsion after ultrasonication was placed at room temperature for a period of time and then placed in a 35°C water bath and stirred slowly; the wall material solution was added dropwise to the core material solution using a separatory funnel, and the stirring was continued using a mechanical stirrer with a stirring speed of 500 r / min and an emulsification time of 20 min; 8% lemon water solution was added dropwise to adjust the pH of the solution to about 2.5 and the reaction was continued for 1 h; after the reaction was completed, the temperature was raised to 68°C, the speed was reduced to 250 r / min, and the reaction was continued for 30 min to obtain a microcapsule solution; after the microcapsule solution was cooled to room temperature, it was filtered with a vacuum pump and dried in a 35°C oven for 5 hours. The powder obtained was the required wave-absorbing microcapsules.

[0046] Example 4:

[0047] like Figure 1As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0048] (1) Add 23 g of urea and 43 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 18 g of triethanolamine. The resulting solution is the wall material solution.

[0049] (2) adding 1.45 g of sodium dodecylbenzenesulfonate to 13.6 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0050] (3) Add 0.5 g of carbonyl iron and 0.45 g of carbon black to the sodium dodecylbenzenesulfonate aqueous solution and slowly stir in a 50 °C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65 °C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0051] (4) After the core material emulsion has been ultrasonicated, it is placed in a water bath at 35°C and stirred slowly. The wall material solution is added dropwise to the core material solution using a separatory funnel and stirred continuously using a mechanical stirrer at a stirring speed of 500 r / min and an emulsification time of 20 min. An 8% lemon water solution is added dropwise to adjust the pH of the solution to about 2.5 and the reaction is continued for 1 h. After the reaction is completed, the temperature is raised to 68°C, the speed is reduced to 250 r / min, and the reaction is continued for 30 min to obtain a microcapsule solution. After the microcapsule solution is cooled to room temperature, it is filtered with a vacuum pump and dried in a 35°C oven for 4 hours. The resulting powder is the desired wave-absorbing microcapsule.

[0052] Example 5:

[0053] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0054] (1) Add 24 g of urea and 44 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 10 g of triethanolamine. The resulting solution is the wall material solution.

[0055] (2) adding 1.8 g of sodium dodecylbenzenesulfonate to 19.25 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0056] (3) Add 0.48 g of carbonyl iron and 0.47 g of carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a 50°C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65°C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0057] (4) The core material emulsion after ultrasonication was placed at room temperature for a period of time and then placed in a water bath at 35°C and stirred slowly; the wall material solution was added dropwise to the core material solution using a separatory funnel, and the stirring was continued using a mechanical stirrer with a stirring speed of 500 r / min and an emulsification time of 20 min; 8% lemon water solution was added dropwise to adjust the pH of the solution to about 2.5 and the reaction was continued for 1 h; after the reaction was completed, the temperature was raised to 68°C, the speed was reduced to 250 r / min, and the reaction was continued for 30 min to obtain a microcapsule solution; after the microcapsule solution was cooled to room temperature, it was filtered with a vacuum pump and dried in an oven at 35°C for 4 hours. The powder obtained was the required wave-absorbing microcapsules.

[0058] Example 6:

[0059] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0060] (1) Add 29.15 g of urea and 30 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 18.8 g of triethanolamine. The resulting solution is the wall material solution.

[0061] (2) adding 2 g of sodium dodecylbenzenesulfonate to 19.5 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0062] (3) Add 0.05 g of carbonyl iron and 0.5 g of carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a 50 °C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65 °C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0063] (4) The core material emulsion after ultrasonication was placed at room temperature for a period of time and then placed in a 35°C water bath and stirred slowly; the wall material solution was added dropwise to the core material solution using a separatory funnel, and the stirring was continued using a mechanical stirrer with a stirring speed of 500 r / min and an emulsification time of 20 min; 8% lemon water solution was added dropwise to adjust the pH of the solution to about 2.5 and the reaction was continued for 1 h; after the reaction was completed, the temperature was raised to 68°C, the speed was reduced to 250 r / min, and the reaction was continued for 30 min to obtain a microcapsule solution; after the microcapsule solution was cooled to room temperature, it was filtered with a vacuum pump and dried in a 35°C oven for 5 hours. The powder obtained was the required wave-absorbing microcapsules.

[0064] Example 7:

[0065] like Figure 1 As shown, this embodiment provides a method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, comprising the following steps:

[0066] (1) Add 15 g of urea and 46 g of 37% formaldehyde aqueous solution into a three-necked flask and stir thoroughly until the urea is dissolved. Adjust the pH to 8.5 with 16.4 g of triethanolamine. The resulting solution is the wall material solution.

[0067] (2) adding 1.7 g of sodium dodecylbenzenesulfonate to 20 g of distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier;

[0068] (3) Add 0.45 g of carbonyl iron and 0.45 g of carbon black to the sodium dodecylbenzenesulfonate aqueous solution and slowly stir in a 50 ° C water bath until the compound is completely and evenly dispersed; then heat the water bath to 65 ° C and continue stirring for 20 min; place the stirred solution in an ultrasonic emulsifier and ultrasonicate for 5 min to obtain a stable core material emulsion;

[0069] (4) The core material emulsion after ultrasonication was placed at room temperature for a period of time and then placed in a water bath at 35°C and stirred slowly; the wall material solution was added dropwise to the core material solution using a separatory funnel, and the stirring was continued using a mechanical stirrer with a stirring speed of 500 r / min and an emulsification time of 20 min; 8% lemon water solution was added dropwise to adjust the pH of the solution to about 2.5 and the reaction was continued for 1 h; after the reaction was completed, the temperature was raised to 68°C, the speed was reduced to 250 r / min, and the reaction was continued for 30 min to obtain a microcapsule solution; after the microcapsule solution was cooled to room temperature, it was filtered with a vacuum pump and dried in an oven at 35°C for 4 hours. The powder obtained was the required wave-absorbing microcapsules.

[0070] Performance Testing

[0071] The absorbing microcapsules of Examples 1-7 were added to Dulux water-based acrylic topcoat at an addition amount of 5 wt %, and then coated on the surface of fiberboard. The fiberboard was purchased from Daya Wood Company and was Daya brand high-density fiberboard (density 830 Kg / m 3 ), with a specification of 100mm×100mm×5mm. The powder was added to the water-based primer at a mass ratio of 5%, and the total amount of primer was controlled to be 4g. The primer coating was coated on the fiberboard with a wet film thickness of 25μm using a SZQ four-sided coating preparation device. After the surface was dried at room temperature for 30 minutes, the first coat of topcoat was applied using a SZQ four-sided coating preparation device. The thickness of the first coat of topcoat was 25μm. After the first coat of topcoat was dried at room temperature for 30 minutes, the second coat of topcoat was applied using a SZQ four-sided coating preparation device. The thickness of the second coat of topcoat was 10μm. After curing at room temperature for 12 hours, the coating gloss (GB / T 4893.6-2013), coating wear resistance (GB / T 4893.8-2013), coating impact resistance (GB / T 4893.9-2013), and wave absorption performance (wave absorption performance was tested by Agilent The electromagnetic parameters of the prepared samples were measured using an E8363C vector network analyzer. The theoretical reflection loss (RL) of the samples was calculated using transmission line theory (the lower the theoretical reflection loss value, the better the material's microwave absorption performance). The paint film anti-cracking performance (GB / T 33569-2017) and paint film transparency were also tested. The samples were then compared with Dulux waterborne acrylic paint without microcapsules and with Dulux waterborne acrylic paint containing unencapsulated carbonyl iron and carbon black (i.e., carbonyl iron and carbon black not formed into microwave-absorbing microcapsules, with the same amounts of carbonyl iron and carbon black added as in Example 1, primarily to demonstrate the microwave absorption function of the carbonyl iron + carbon black combination). The test results are shown in Table 1 below.

[0072] Table 1 shows the test results:

[0073]

[0074] The present invention mainly uses the experiment of modifying water-based coating with microcapsules to make the coating have low gloss and abrasion resistance, impact resistance, wave absorption performance and anti-cracking performance. The microcapsules of the present invention are added in an amount of 5% to a water-based coating on a wood material surface. After the microcapsules are added, the glossiness of the paint film is tested using a gloss meter according to GB / T 4893.6-2013, and the glossiness of the coating film is matte. According to the national standard GB / T 4893.8-2013, the abrasion resistance of the coating film is tested using a paint film abrasion meter, and the abrasion resistance is level 1 (abrasion revolution number of 5000 revolutions). According to GB / T 4893.9-2013, the impact resistance of the paint film is measured using an impact tester, and the impact resistance height is 50 cm. The electromagnetic parameters of the absorbing material at 2-20 GHz are tested using an Agilent E8363C vector network analyzer, and the theoretical reflection loss value of the microcapsules is measured to be between -13 and -20 dB depending on the content of each component constituting the microcapsule. According to GB / T33569-2017, the anti-cracking performance of the paint film is measured using an artificial aging test, and the paint film does not crack.

[0075] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention is based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by those skilled in the art fall within the protection scope of the present invention.

Claims

1. A method for preparing microwave-absorbing microcapsules suitable for transparent water-based coatings on wood surfaces, characterized in that: The wave-absorbing microcapsules suitable for transparent water-based paint on wood surfaces include the following raw materials in parts by weight: 20 to 27 parts by weight of urea, 34 to 44 parts by weight of a 37% formaldehyde solution, 13 to 19 parts by weight of triethanolamine, 0.1 to 0.4 parts by weight of carbonyl iron, 0.08 to 0.3 parts by weight of carbon black, 0.1 to 1.5 parts by weight of sodium dodecylbenzenesulfonate, and 8 to 18 parts by weight of distilled water; The preparation method comprises the following steps: (1) Mix urea and formaldehyde aqueous solution, stir thoroughly until the urea is dissolved, and adjust the pH with triethanolamine. The resulting solution is the wall material solution; (2) adding sodium dodecylbenzenesulfonate to distilled water and stirring until completely dissolved to obtain an aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier; (3) Add carbonyl iron and carbon black to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stir in a water bath at a certain temperature until the compound is completely and evenly dispersed; then continue stirring after heating to a certain temperature; ultrasonically treat the stirred solution to obtain a stable core material emulsion; (4) The core material emulsion after ultrasonic treatment is placed at room temperature for a period of time and then placed in a water bath for stirring; the wall material solution is added dropwise to the core material emulsion using a separatory funnel, and the stirring is continued, and the lemon water solution is added dropwise; after the reaction is completed, the temperature is raised to the preset temperature, the stirring speed is reduced, and the reaction is continued to obtain a microcapsule solution; after the microcapsule solution is cooled to room temperature, it is filtered and dried, and the obtained powder is the wave-absorbing microcapsule suitable for transparent water-based coatings on wood surfaces.

2. The method for preparing the microwave-absorbing microcapsules suitable for transparent water-based paint on wood surface according to claim 1, characterized in that: In step (1), urea and formaldehyde aqueous solution are added to a three-necked flask, stirred thoroughly until the urea is dissolved, and the pH is adjusted to 8.5 with triethanolamine. The resulting solution is the wall material solution.

3. The method for preparing the microwave-absorbing microcapsules suitable for transparent water-based paint on wood surface according to claim 1, characterized in that: In step (3), carbonyl iron and carbon black are added to an aqueous solution of sodium dodecylbenzenesulfonate and slowly stirred in a 50°C water bath until the compound is completely and evenly dispersed; the temperature is then raised to 65°C and stirring is continued for 20 minutes; the stirred solution is placed in an ultrasonic emulsifier and ultrasonicated for 5 minutes to obtain a stable core material emulsion.

4. The method for preparing the microwave-absorbing microcapsules suitable for transparent water-based paint on wood surface according to claim 1, characterized in that: In step (4), the core material emulsion after ultrasonic treatment is placed at room temperature for a period of time and then placed in a water bath at 35°C for stirring; the wall material solution is added dropwise to the core material emulsion using a separatory funnel, and the stirring is continued using a mechanical stirrer, and an 8% lemon water solution is added dropwise to adjust the pH of the solution to 2.5, and the reaction is carried out for 1 hour; after the reaction is completed, the temperature is raised to 68°C, the speed is reduced to 250r / min, and the reaction is continued for 30 minutes to obtain a microcapsule solution; after the microcapsule solution is cooled to room temperature, it is filtered with a vacuum pump, and the powder obtained after drying in an oven is the wave-absorbing microcapsule suitable for transparent water-based coatings on wood surfaces.

5. The method for preparing the microwave-absorbing microcapsules suitable for transparent water-based paint on wood surface according to claim 4, characterized in that: In step (4), the drying temperature is 35°C and the drying time is 3-5 hours.

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