A coating for purifying indoor formaldehyde and its preparation method

Abstract

The present invention discloses a coating for purifying indoor formaldehyde and its preparation method. The coating contains a noble metal-based molecular sieve catalytic material that can adsorb indoor formaldehyde molecules at room temperature and catalytically oxidize them, completely converting them into non-toxic CO2 and H2O. The coating also exhibits excellent coating properties and can be directly applied to indoor walls. While providing protection and decoration, it also provides a large reaction surface for the noble metal-based molecular sieve catalytic material to purify formaldehyde, fully demonstrating its catalytic formaldehyde removal capability at room temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection and coatings, in particular to a coating for purifying indoor formaldehyde and a preparation method thereof. Background Art

[0002] Indoor air pollution has become a significant factor affecting people's health, and formaldehyde pollution is a common indoor air pollutant. Formaldehyde has strong carcinogenic and cancer-promoting effects. Extensive literature documents that formaldehyde's impacts on human health primarily manifest in abnormal smells, irritation, allergies, abnormal lung and liver function, and immune dysfunction. At concentrations of 0.06 to 0.07 mg / m³, children can experience mild asthma. Formaldehyde levels of 0.1 mg / m³ in indoor air can cause an unpleasant odor and discomfort; 0.5 mg / m³ can irritate the eyes and cause tearing; 0.6 mg / m³ can cause throat discomfort or pain. Higher concentrations can cause nausea, vomiting, coughing, chest tightness, asthma, and even pulmonary edema. Reaching 30 mg / m³ can be immediately fatal. People often decorate their homes and offices and purchase furniture. This process requires the use of large quantities of artificial boards (such as plywood, core board, medium-density fiberboard, particleboard, laminate flooring, and engineered wood flooring). The production of these boards requires the use of adhesives made from highly toxic formaldehyde. This formaldehyde release period is long, typically up to 15 years, making it a major indoor air pollutant. Therefore, removing formaldehyde from indoor air is crucial for human health.

[0003] Formaldehyde is a toxic and harmful gas. Current methods for removing formaldehyde mainly include physical adsorption and chemical decomposition. Physical adsorption involves capturing formaldehyde molecules in the air using porous materials with adsorption properties. CN1386577 discloses a method for adsorbing formaldehyde using activated carbon. Although this method initially removes formaldehyde quickly and effectively, with a large adsorption capacity, it suffers from poor sustainability and is prone to desorption. After a period of use, the activated carbon must be discarded and replaced, increasing the cost of formaldehyde removal. Chemical decomposition involves a chemical reaction between formaldehyde molecules and oxygen under the action of a catalyst, converting them into non-toxic and harmless CO2 and H2O. Existing formaldehyde catalytic purification coatings mostly rely on photocatalysis. CN115124896A discloses a wall coating and its preparation method for purifying formaldehyde. Although this method demonstrates a certain degree of formaldehyde purification capability, it is limited by external conditions such as light and cannot guarantee sustained, stable, and efficient formaldehyde purification under indoor conditions. The formaldehyde purification technology of this patent provides a precious metal-based molecular sieve catalytic material, which not only uses the rich pores of the molecular sieve to adsorb formaldehyde, but also uses the strong oxidizing precious metal active centers to catalyze the oxidation of formaldehyde and permanently remove it. It can also achieve efficient formaldehyde purification at room temperature and is not limited by external conditions such as light.

[0004] While precious metal-based molecular sieve catalytic materials possess excellent physical adsorption capacity for formaldehyde and can efficiently degrade it through catalysis, their direct application in everyday living environments is currently unavailable. Paint, an essential indoor wall protection and decorative material, not only acts as a binder, allowing our precious metal-based molecular sieve catalytic materials to adhere to the wall, but also, once the paint dries and forms a film, its vast surface creates a reaction interface for the precious metal-based molecular sieve catalytic material to catalyze the oxidation of formaldehyde. Therefore, we have developed a paint based on precious metal-based molecular sieve catalytic materials for indoor formaldehyde purification, which can effectively and continuously remove indoor formaldehyde. Summary of the Invention

[0005] The present invention provides a coating for purifying indoor formaldehyde and a preparation method thereof. The coating can be directly applied on indoor walls, adsorbs indoor formaldehyde molecules at room temperature and catalytically oxidizes them into non-toxic and harmless CO2 and H2O.

[0006] To achieve the above object, the present invention provides a coating for purifying indoor formaldehyde, comprising the following components calculated in parts by mass:

[0007] Porous catalytic material: 13-26 parts;

[0008] Epoxy resin: 6-10 parts;

[0009] Inorganic binder: 25-33 parts;

[0010] Water: 27-32 parts;

[0011] Emulsifier: 6-10 parts;

[0012] Defoaming agent: 0.5-1 part;

[0013] Leveling agent: 0.5-1 part;

[0014] Dispersant: 1.5-2 parts;

[0015] Curing agent: 0.5-1 part;

[0016] pH regulator: 0-1 part;

[0017] The epoxy resin is a composite of one or more epoxy resins E-44, epoxy resin E-20, epoxy resin E-51, etc.; the inorganic binder is a composite of one or more silica sol, silicate, phosphate, aluminum sol, etc.; the emulsifier is a composite of one or more alkylphenol polyoxyethylene ether, polyethylene glycol, hexadecyltrimethylammonium bromide, etc.; the defoamer is a composite of one or more phosphate ester, polyether-modified polysiloxane, etc.; the leveling agent is a composite of one or more polydimethylsiloxane, polyfluorinated polyolefin, acrylic acid homopolymer, etc.; the dispersant is a composite of one or more sodium polyacrylate, sodium diisobutylnaphthalene sulfonate, sodium tripolyphosphate, etc.; the curing agent is a composite of one or more polyamide, epoxy-polyamine adduct, amidated polyamine, etc.; the pH adjuster is a composite of one or more sodium bicarbonate, ammonia water, ethanolamine, etc.

[0018] The porous catalytic material is a noble metal-based molecular sieve, and its preparation method comprises the following steps:

[0019] Thoroughly mix a certain amount of molecular sieve with a solution of precious metal cations. Add a certain amount of reducing agent while rapidly stirring. After a period of reaction, wash the product several times with deionized water by centrifugation. After drying at a certain temperature and reducing it with hydrogen, the precious metal-based molecular sieve product is obtained. This product is then crushed and ground to a particle size of less than 74 microns.

[0020] The molecular sieve is a composite of one or more of S-1 (Silicalite-1), TS-1 (Titanium Silicalite-1), and ZSM-5. The precious metal comprises one or more of platinum, palladium, ruthenium, and rhodium. The mass fraction of the precious metal in the precious metal-based molecular sieve material is 0.2% to 0.5%. The reducing agent is one or more of sodium borohydride, ethylene glycol, and ascorbic acid, with the molar ratio of reducing agent to precious metal being 50:1 to 300:1.

[0021] There are no special requirements for the stirring time, drying temperature, reduction temperature and time in the above steps. The stirring time is, for example, but not limited to, 2 to 10 hours; the drying temperature is, for example, but not limited to, 40 to 80 degrees Celsius; the hydrogen reduction temperature is, for example, but not limited to, 50 to 500 degrees Celsius; and the reduction time is, for example, but not limited to, 1 to 10 hours.

[0022] The preparation method of the above-mentioned coating for purifying indoor formaldehyde comprises the following steps:

[0023] Step 1: Mix a certain amount of water and epoxy resin under high-speed stirring, add emulsifier dropwise at a certain temperature, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0024] Step 2: Mix a certain amount of water and inorganic binder under rapid stirring, stir for a certain period of time, add epoxy resin emulsion, disperse evenly, then add defoamer and leveling agent, keep stirring evenly and disperse for a certain period of time, add pH regulator to adjust the pH to 7.5-9, continue to add a certain weight ratio of porous catalytic material, dispersant, and curing agent, stir for a period of time to obtain the final product, and seal for storage.

[0025] When the paint is used in air purification, the wall surface should be smooth without obvious grooves or protrusions, and the indoor relative humidity should be kept at 35% to 55%. The coating thickness of the paint is 0.8 to 1.2 mm.

[0026] A coating for purifying indoor formaldehyde provided by the present invention has at least the following beneficial effects:

[0027] The present invention uses a precious metal-based molecular sieve as the core material in the coating, which can efficiently adsorb formaldehyde and catalytically oxidize the adsorbed formaldehyde molecules into non-toxic CO2 and H2O at room temperature. As shown in Example 1, the indoor formaldehyde purification efficiency reaches 98% within 24 hours, and the purification efficiency does not decrease, showing excellent formaldehyde purification performance and long-term purification. At the same time, the addition of the catalytic material does not affect the basic performance of the coating. The coating has good coating properties, such as a surface dry time of 1.8 hours and a wash resistance of 654 times. All of these meet the requirements of GB / T9756-2018 and demonstrate good coating performance. DETAILED DESCRIPTION

[0028] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0029] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0030] The formaldehyde purification coating of the present invention is specifically prepared by the following process:

[0031] Example 1

[0032] Step 1: Mix 1 gram of TS-1 (Titanium silicate-1) with 3.138 milliliters of a 0.125 mol / ml palladium chloride solution and stir at 500-600 rpm. After 30 minutes, quickly add 0.5 grams of sodium borohydride. After 6 hours, centrifuge and wash three times with deionized water. Dry at 50 degrees Celsius and reduce with hydrogen to obtain a porous catalytic material product. Finally, grind the prepared porous catalytic material to a particle size of less than 74 microns.

[0033] Step 2: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0034] Step 3: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Then add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0035] Step 4: Add 8.75 grams of the porous catalytic material prepared above, stir for 90 minutes, add 0.6 grams of sodium polyacrylate, stir for 1.5 hours, add 0.2 grams of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain Example 1, and seal for storage.

[0036] Example 2

[0037] Step 1: Mix 1 gram of S-1 (Silicalite-1) with 3.138 milliliters of a 0.125 mol / ml palladium chloride solution and stir at 500-600 rpm. After 30 minutes, quickly add 0.5 grams of sodium borohydride. After 6 hours, centrifuge and wash three times with deionized water. Dry at 50 degrees Celsius and reduce with hydrogen to obtain a porous catalytic material product. Finally, grind the prepared porous catalytic material to a particle size of less than 74 microns.

[0038] Step 2: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0039] Step 3: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Then add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0040] Step 4: Add 8.75 grams of the porous catalytic material prepared above, stir for 90 minutes, add 0.6 grams of sodium polyacrylate, stir for 1.5 hours, then add 0.2 grams of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain Example 2, and seal for storage.

[0041] Example 3

[0042] Step 1: Mix 1 gram of ZSM-5 with 3.138 milliliters of a 0.125 mol / ml palladium chloride solution and stir at 500-600 rpm. After 30 minutes, quickly add 0.5 grams of sodium borohydride. After 6 hours, centrifuge and wash three times with deionized water. Dry at 50 degrees Celsius and reduce with hydrogen to obtain a porous catalytic material product. Finally, grind the prepared porous catalytic material to a particle size of less than 74 microns.

[0043] Step 2: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0044] Step 3: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Then add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0045] Step 4: Add 8.75 grams of the porous catalytic material prepared above, stir for 90 minutes, add 0.6 grams of sodium polyacrylate, stir for 1.5 hours, then add 0.2 grams of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain Example 3, and seal for storage.

[0046] Example 4

[0047] Step 1: Mix 1 gram of TS-1 (Titanium silicate-1) with 3.138 milliliters of a 0.125 mol / ml palladium chloride solution and stir at 500-600 rpm. After 30 minutes, quickly add 0.5 grams of sodium borohydride. After 6 hours, centrifuge and wash three times with deionized water. Dry at 50 degrees Celsius and reduce with hydrogen to obtain a porous catalytic material product. Finally, crush and grind the prepared porous catalytic material to a particle size of less than 74 microns.

[0048] Step 2: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0049] Step 3: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Then add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0050] Step 4: Add 6.56 grams of the porous catalytic material prepared above, stir for 90 minutes, add 0.6 grams of sodium polyacrylate, stir for 1.5 hours, add 0.2 grams of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain Example 4, and seal for storage.

[0051] Example 5

[0052] Step 1: Mix 1 gram of TS-1 (Titanium silicate-1) with 3.138 milliliters of a 0.125 mol / ml palladium chloride solution and stir at 500-600 rpm. After 30 minutes, quickly add 0.5 grams of sodium borohydride. After 6 hours, centrifuge and wash three times with deionized water. Dry at 50 degrees Celsius and reduce with hydrogen to obtain a porous catalytic material product. Finally, grind the prepared porous catalytic material to a particle size of less than 74 microns.

[0053] Step 2: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin emulsion.

[0054] Step 3: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Then add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0055] Step 4: Add 4.63 grams of the porous catalytic material prepared above, stir for 90 minutes, add 0.6 grams of sodium polyacrylate, stir for 1.5 hours, add 0.2 grams of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain Example 5, and seal for storage.

[0056] Comparative Example

[0057] Step 1: Mix 2.5 g of water and 2.5 g of epoxy resin E-44 at a rotation speed of 800-900 rpm, add 2.5 g of polyethylene glycol dropwise at 40 degrees Celsius, and stir to obtain a uniformly dispersed epoxy resin solution.

[0058] Step 2: Mix 7.5 grams of water and 10 grams of silica sol at 300-400 rpm. Stir for 20 minutes. Add 7.5 grams of epoxy resin emulsion and disperse evenly. Then add 0.25 grams of phosphate ester. Stir at 700-800 rpm and add 0.2 grams of polydimethylsiloxane. Maintain this speed for 2 hours, then add ammonia water to adjust the pH to 8.

[0059] Step 3: After stirring for 90 minutes, add 0.6 g of sodium polyacrylate, stir for 1.5 hours, add 0.2 g of polyamide curing agent dropwise, stir at 40 degrees Celsius for 2 hours to obtain a comparative example product, and seal and store.

[0060] Performance Testing

[0061] 1. Formaldehyde purification effect

[0062] In order to further demonstrate the purification performance of the air purification coating obtained in the embodiment of the present invention, the formaldehyde purification performance of Examples 1 to 5 and the comparative example were compared.

[0063] The specific method is as follows:

[0064] S1. Sample preparation

[0065] According to the usage and construction method of the sample to be tested, the sample shall be evenly applied to the base paper of 210mm×297mm (the coating thickness is 1mm±0.2mm), and the test shall be carried out under a certain room temperature (25 degrees Celsius±5 degrees Celsius) and a certain humidity (45%±5%).

[0066] S2. Formaldehyde gas generation and detection

[0067] Liquid formaldehyde is vaporized by a formaldehyde gas generator and introduced into a sealed test chamber (1m*1m*1m). A fan within the chamber diffuses the formaldehyde, achieving a stable and uniform formaldehyde concentration (5ppm±0.5ppm) within a short period of time. The present invention uses an electrochemical formaldehyde sensor located in the center of the chamber to monitor formaldehyde concentration in real time.

[0068] S3. Test chamber stability test

[0069] Place blank base paper in the chamber. Once the formaldehyde has evenly diffused and the concentration has stabilized, monitor and record the formaldehyde concentration for 48 hours. Calculate the natural decay rate from the measured initial and final formaldehyde concentrations. This decay rate should be subtracted from the subsequent sample purification test. Since the natural decay rate of this device is extremely small (<1%), it can be ignored. Repeat the natural decay test every one to two weeks to ensure stability.

[0070]

[0071] Where: R-natural decay rate (%); C0-initial concentration (ppm); C1-final concentration (ppm).

[0072] S4. Sample testing

[0073] Samples coated with the products of Examples 1-5 and the comparative example were placed in a test chamber to evaluate their formaldehyde purification activity. The experiment lasted 24 hours, from the time the formaldehyde concentration stabilized until the experiment was terminated. The formaldehyde purification efficiency of each product was calculated using the following formula:

[0074]

[0075] Where: r-formaldehyde conversion rate (%); - Initial concentration (ppm); -Stop concentration (ppm).

[0076] After 24 hours, formaldehyde gas was introduced into the test chamber again. -initial concentration, a secondary formaldehyde purification activity evaluation experiment was conducted, and the purification durability was evaluated by testing the secondary formaldehyde conversion rate of the products of Examples 1 to 5 and the comparative example.

[0077] Table 1 Formaldehyde conversion data of Examples 1 to 5 and Comparative Examples

[0078]

[0079] The above data demonstrates that the coatings incorporating precious metal-based molecular sieves exhibit excellent formaldehyde purification performance. Example 5 achieved a formaldehyde purification efficiency of 79%, while Examples 2-4 all exceeded 80%, and Example 1 even achieved a formaldehyde purification efficiency of 98%. Compared to Examples 2 and 3, Example 1, which incorporates a precious metal-based molecular sieve loaded with palladium using TS-1 as a carrier, exhibited even better formaldehyde purification performance. Comparing Examples 1, 4, and 5, the formaldehyde purification efficiency further improved with increasing amounts of porous catalytic material. The secondary formaldehyde conversion data demonstrate that the secondary formaldehyde conversion rate for the comparative example is zero, indicating that formaldehyde purification occurs via adsorption, possessing a certain adsorption capacity. Once the adsorption threshold is reached, formaldehyde purification ceases. The formaldehyde conversion rates for Examples 1-5 remained unchanged, demonstrating that Examples 1-5 are able to catalytically oxidize adsorbed formaldehyde, ensuring the coating's long-term formaldehyde purification performance and excellent purification durability and stability. The formaldehyde purification efficiency for Example 1 remained at 98%, demonstrating excellent formaldehyde purification stability.

[0080] 2. Coating performance

[0081] The coating properties of the formaldehyde purification coatings in Examples 1 to 5 and the comparative example were tested with reference to the standard of "Synthetic Resin Emulsion Interior Wall Paint" (GB / T9756-2018):

[0082] 1. Status in the container

[0083] Open the container and stir with a spatula or stirring rod. If there is no precipitation or lumps and it is easy to mix evenly, it will be rated as "no hard lumps, uniform state after stirring".

[0084] 2. Construction

[0085] Apply the sample to the smooth surface of the test panel with a brush, maintaining a wet film thickness of approximately 100 microns. Hold the panel upright with its long side horizontal and its short side at an angle of 85° to the horizontal. After 6 hours, apply a second coat of the sample using the same method. If the brush can be applied without difficulty during the second coat, the panel is considered "unobstructed in applying two coats."

[0086] 3. Low temperature film forming

[0087] Place a 200g sample, substrate and a 20μm gap wet film preparation device in an environment with a temperature of (5 degrees Celsius ± 1 degree Celsius). Take them out after 2 hours and apply a stroke with the wet film preparation device within 30 seconds. Put the test plate back immediately. Take out the test plate after 24 hours and immediately check the degree of dryness according to the surface dry method in GB / T 1728-1979 and visually inspect the appearance of the coating. If the coating is dry and there is no cracking, blooming or obvious shrinkage, it is rated as "no abnormality in film formation at 5 degrees Celsius".

[0088] 4. Coating appearance

[0089] After the workability test, place the test piece for 24 hours and visually observe the coating film. If there is no obvious shrinkage hole and the coating film is uniform, it is rated as "normal".

[0090] 5. Drying time

[0091] It is carried out according to the provisions of the surface-dried ethyl method in GB / T1728-1979.

[0092] 6. Contrast ratio

[0093] According to the provisions of GB / T 23981-2009, the reflectivity of the coating on the black and white substrates is measured by a reflectivity meter, and the ratio of the reflectivity on the black substrate to the reflectivity on the white substrate is calculated to obtain the contrast ratio.

[0094] 7. Alkali resistance

[0095] According to the provisions of GB / T 9265-2009, if at least two of the three test panels do not show any abnormal coating phenomena such as blistering and powdering, they can be assessed as "no abnormality".

[0096] 8. Washability

[0097] Conduct arbitration inspections in accordance with the provisions of GB / T 9266-2009. Use a brush with a maximum bristle load within the range of (190 ± 40) Newtons. Conduct parallel tests on two specimens for the same test piece. Scrub until the center 100mm of the specimen's length exposes the substrate. Report the result based on the specimen with the greater number of scrubbings.

[0098] The specific data are shown in the following table.

[0099] Table 2 Coating performance test of Examples 1 to 5 and Comparative Examples

[0100]

[0101]

[0102] The above test results show that Examples 1 to 5 and the comparative example have no lumps in the container and are in a uniform state after stirring, are brushed in two coats without obstacles, have good construction properties, no abnormal film formation at 5 degrees Celsius, good low-temperature stability, no abnormal alkali resistance for 24 hours, normal film appearance, surface drying time of less than 2 hours, contrast ratios greater than 0.9, and wash resistances of more than 350 times, all meeting the requirements of the national standard (synthetic resin emulsion interior wall paint, GB / T9756-2018). As the proportion of porous catalytic material increases, although the performance of the coating decreases slightly, it still exceeds the technical indicators specified in the standard and has good coating performance.

[0103] In summary, the coating for purifying indoor formaldehyde proposed by the present invention has good formaldehyde purification performance. For example, the formaldehyde conversion rate in Example 1 can reach 98% within 24 hours. At the same time, all performance indicators of the coating meet the national standard (synthetic resin emulsion interior wall coating, GB / T9756-2018), showing good coating performance.

[0104] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A coating for purifying formaldehyde in a room, characterized in that: Its components are calculated by mass as follows: Porous catalytic material: 13-26 parts; Epoxy resin: 6-10 parts; Inorganic binder: 25~33 parts; Water: 27-32 parts; Emulsifier: 6-10 parts; Defoaming agent: 0.5~1 part; Leveling agent: 0.5~1 part; Dispersant: 1.5~2 parts; Curing agent: 0.5~1 part; pH regulator: 0~1 part; The porous catalytic material is a noble metal-based molecular sieve material, wherein the molecular sieve is a composite of one or more of S-1 (Silicalite-1), TS-1 (Titaniumsilicalite-1), and ZSM-5; the noble metal comprises one or more of platinum, palladium, ruthenium, and rhodium; and the mass fraction of the noble metal in the porous catalytic material is 0.2% to 0.5%; The noble metal-based molecular sieve material is prepared by the following method: The molecular sieve and the noble metal cation solution are thoroughly mixed; a reducing agent is added under rapid stirring; after the reaction is complete, the product is centrifuged and washed multiple times with deionized water; after drying, the product is reduced with hydrogen to obtain a noble metal-based molecular sieve catalyst product, which is then ground to a particle size of less than 74 microns; The reducing agent is one or more of sodium borohydride, ethylene glycol and ascorbic acid; the molar ratio of the added reducing agent to the noble metal is 50:1-300:

1.

2. A coating for purifying indoor formaldehyde according to claim 1, characterized in that: The reaction time is 2 to 10 hours; the drying temperature is 40 to 80 degrees Celsius; the hydrogen reduction temperature is 50 to 500 degrees Celsius, and the reduction time is 1 to 10 hours.

3. A method for preparing a coating for purifying indoor formaldehyde as claimed in claim 1, characterized in that: The steps include: Step 1: Mix water and epoxy resin under high-speed stirring, add emulsifier dropwise, and stir to obtain a uniformly dispersed epoxy resin emulsion; Step 2: Mix water and inorganic binder under rapid stirring, stir for a while, add epoxy resin emulsion, disperse evenly, then add defoamer and leveling agent, keep stirring evenly and disperse for a while, add pH regulator to adjust the pH to 7.5~9, continue to add porous catalytic material, dispersant, curing agent, stir for a while to obtain the final product, and seal for storage.

4. The method for preparing a coating for purifying indoor formaldehyde according to claim 3, wherein: The epoxy resin is a composite of one or more of epoxy resin E-44, epoxy resin E-20, and epoxy resin E-51; the inorganic binder is a composite of one or more of silica sol, silicate, phosphate, and aluminum sol; the emulsifier is a composite of one or more of alkylphenol polyoxyethylene ether, polyethylene glycol, and hexadecyltrimethylammonium bromide; the defoamer is a composite of one or more of phosphate ester and polyether-modified polysiloxane; the leveling agent is a composite of one or more of polydimethylsiloxane, polyfluorinated polyolefin, and acrylic acid homopolymer; the dispersant is a composite of one or more of sodium polyacrylate, sodium diisobutylnaphthalene sulfonate, and sodium tripolyphosphate; the curing agent is a composite of one or more of polyamide, epoxy-polyamine adduct, and amidated polyamine; and the pH adjuster is a composite of one or more of sodium bicarbonate, ammonia water, and ethanolamine.

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