Transparent patch capable of continuously purifying formaldehyde and preparation method of transparent patch

Abstract

The preparation method comprises the following steps: firstly, taking a PET (Polyethylene Terephthalate) film as a base material, and compounding medical non-toxic acrylate coating glue on the surface of the PET film; secondly, bonding a nano carbon nitride sol-gel film on a base material, spraying a CaO solution, and drying; and finally, sequentially growing the three molecular sieve crystals on the surface of the carrier to form a film. The molecular sieve aperture and the specific surface area of the adsorption layer are sequentially decreased from outside to inside, a polymolecular layer with a long and narrow pore channel is formed, diffusion of formaldehyde gas molecules in the polymolecular layer is facilitated, and the efficient and accurate adsorption effect is achieved through strong coulomb force. The adopted nano carbon nitride has a visible light response function and can degrade formaldehyde into carbon dioxide and water, and the added nano calcium oxide can well adsorb photocatalytic products (carbon dioxide and water), so that the adverse effect of competitive adsorption between water vapor and formaldehyde particles caused by the strong hydrophilicity of a molecular sieve is eliminated, and the formaldehyde adsorption effect is improved. Therefore, the benefit of efficient and sustainable use is achieved.

Description

Technical Field

[0001] This invention belongs to the field of air purification, specifically relating to a transparent sticker for sustainable formaldehyde purification and its preparation method. Background Technology

[0002] Formaldehyde, a colorless indoor pollutant with a pungent odor, has a particle size of 0.45 mm. When the concentration reaches 900 μg / m³... 3 Formaldehyde poses a significant threat to human health and has garnered widespread attention. Classified as a Group 1 possible carcinogen, long-term exposure to low concentrations can irritate the eyes and nose, increase the risk of chronic respiratory diseases, and cause nasopharyngeal carcinoma, brain cancer, and other conditions. Children and pregnant women are particularly sensitive to formaldehyde and face even greater risks. Despite its significant harm, formaldehyde remains widely used in industrial production of building products and wood products due to its low cost, such as plywood, fiberboard, varnishes, paints, and furniture. These home decoration materials are sources of formaldehyde emissions indoors. Among materials and products that widely produce formaldehyde, especially building furniture, indoor formaldehyde concentrations are 2 to 10 times higher than outdoor levels. Purifying indoor formaldehyde and other harmful gases is essential. Most methods involve opening windows for ventilation, using air purifiers, or employing plants to remove formaldehyde, but these methods are relatively weak in targeting, have low removal efficiency, and require long processing times. Combining green and sustainable photocatalytic air purification technology with highly efficient molecular sieve adsorption materials is one of the most promising green methods for precisely, quickly, and maximally purifying indoor gases.

[0003] Current research on photocatalytic gas purification largely focuses on the preparation of photocatalytic gas purification materials using titanium dioxide. Patent CN105295726A discloses a formaldehyde adsorption coating and its manufacturing method; CN114272958A discloses a platinum catalyst for rapid formaldehyde removal; and CN210481273U discloses a transparent glass explosion-proof film for formaldehyde removal. However, most photocatalytic materials use titanium dioxide, which only works under ultraviolet light and cannot achieve efficient collection and adsorption followed by degradation of the generated formaldehyde. This invention combines efficient molecular sieve adsorption with visible light photocatalysis using carbon nitride. The molecular sieve, with its large specific surface area, pore size, large adsorption capacity, and numerous surface active sites, allows formaldehyde and other harmful gas molecules to diffuse fully within the sieve, achieving efficient adsorption. Carbon nitride, as a novel non-metallic polymer photocatalyst with visible light response, high chemical stability, wide availability of raw materials, and low cost, has received significant attention in the field of photocatalytic environmental pollution control in recent years. Compared to TiO2, which is only effective under ultraviolet light, carbon nitride can function under visible light, thus improving the efficiency of formaldehyde catalytic degradation into carbon dioxide and water. A foreign literature (Krivtsov, I., Mitoraj, D., et al. (2020). Water‐soluble polymeric carbon nitridecolloidal nanoparticles for highly selective quasi‐homogeneous photocatalysis. Angewandte Chemie International Edition, 59.) discloses a method for preparing water-soluble polymeric carbon nitride colloidal nanoparticles. This type of carbon nitride exhibits superior photocatalytic degradation efficiency and is more sustainably recyclable compared to ordinary carbon nitride. This invention uses the water-soluble polymeric carbon nitride colloidal nanoparticles from this literature as a source of fully soluble nano-carbon nitride. The material is environmentally friendly and safe, has a long lifespan, and requires no consumption or energy, making it of great significance to human health. Summary of the Invention

[0004] The purpose of this invention is to provide a transparent patch for sustainable formaldehyde purification and its preparation method. It is similar in appearance to a band-aid. Simply stick it to the holes in building furniture to directly adsorb formaldehyde and degrade it through photocatalysis. It is simple, direct and efficient to operate.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A transparent sticker for sustainable formaldehyde purification mainly comprises four parts: a transparent substrate layer, an adhesive layer, a photocatalyst layer, and an adsorption layer; the upper surface of the transparent substrate layer consists of the adhesive layer, the photocatalyst layer, and the adsorption layer in sequence.

[0006] The transparent substrate layer is a PET film layer with a thickness of 100~200 μm, a light transmittance of greater than 90%, and a haze of less than 2%.

[0007] The adhesive layer is a medical-grade non-toxic acrylic coating, similar to that used in medical bandages, and has a thickness of 35~45μm.

[0008] The photocatalyst layer is composed of a nano carbon nitride sol-gel film and nano calcium oxide, wherein the nano carbon nitride particles have a diameter of 10±3 nm and are prepared by adding a strong acid (such as HCl) to a 0.75 g / L completely soluble nano carbon nitride solution, and the thickness of the photocatalyst layer is 15~20 μm.

[0009] 10-15 g of nano-calcium oxide particles with a particle size of 10-80 nm were uniformly dispersed in 20-25 ml of ethanol as an organic solvent for 30-40 minutes, and then uniformly sprayed onto the surface of nano-carbon nitride sol-gel film. After drying for 90-120 minutes, a photocatalyst layer (3) was prepared. Calcium oxide can effectively enrich H2O and CO2 generated by photocatalytic degradation, thereby eliminating the adverse effects of competitive adsorption between water vapor and formaldehyde particles caused by the strong hydrophilicity of molecular sieves.

[0010] The adsorption layer is a molecular sieve adsorption film, wherein the molecular sieve used is a synthetic mesoporous molecular sieve MCM-41, a 13X type, and a 5A type, with specific surface areas of 900~1000 m² respectively. 2 / g, 400~500 m 2 / g, 300~400 m 2 / g, with pore sizes of 2~5 nm, 1 nm, and 0.5 nm respectively. MCM-41 molecular sieve and 13X type molecular sieve need to be sieved through a 200-mesh sieve, heat-treated in an oven at 150~200℃ for 5~6 hours, and activated at 400℃ for 2~3 hours for pretreatment to achieve better adsorption effect. Type 5A molecular sieve only needs to be sieved through a 200-mesh sieve and does not need to be calcined to prevent crystallization. The molecular sieve adsorption film uses a polymer precursor film containing a transparent substrate layer, an adhesive layer, and a photocatalyst layer as the substrate carrier. The three types of molecular sieves are respectively mixed with water as a solvent and magnetically stirred for 30~45 minutes to prepare a molecular sieve mother liquor with a concentration of 15~30 mol / L. The carrier is first immersed in the 5A type molecular sieve mother liquor using an in-situ hydrothermal synthesis method and heated at 100℃ for 2~5 hours in an inert atmosphere. After 2 hours, the film is removed and coated with a casting solution of 14% by mass on the surface of the carrier to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting solution film formation method is used to impregnate the 13X and MCM-41 molecular sieve mother liquors in sequence to form a film, so that the three types of molecular sieve crystal particles grow into films on the surface of the carrier in sequence, and are wrapped on the surface of the photocatalyst layer and connected to the adhesive layer. The thickness of the adsorption layer is 30~40μm.

[0011] Furthermore, the casting solution mainly consists of dimethyl sulfoxide, triethyl phosphate, and dimethylacetamide.

[0012] The present invention has the following advantages: (1) Compared with simply opening windows for ventilation after decoration to remove formaldehyde, benzene and other toxic gases, the transparent sticker is applied to the holes in the furniture board and the holes that easily emit formaldehyde, which makes it more targeted, efficient and easy to operate. According to the test, its formaldehyde removal rate is as high as 99.6%.

[0013] (2) The molecular sieve adsorption layer of the present invention is a multi-molecular layer adsorption. The 5A, 13X and MCM-41 molecular sieves are composited on the surface of the polymer precursor film by in-situ hydrothermal synthesis. Their pore size and specific surface area decrease from the outside to the inside, forming a multi-molecular layer with narrow and long pore channels. This is conducive to the diffusion of formaldehyde gas molecules inside the molecular sieve. Through the strong Coulomb force of the multi-level pore size, the formaldehyde particles are efficiently adsorbed layer by layer and diffused into the pores inside the adsorption layer, thereby achieving the effect of stronger adsorption force and greater adsorption amount.

[0014] (3) Compared with titanium dioxide, which can only function under ultraviolet light, the nano carbon nitride sol of the photocatalytic layer has visible light response function. After adsorbing formaldehyde in the adsorption layer, it produces a photocatalytic effect under indoor light, which can degrade formaldehyde into carbon dioxide and water, and has a good sustainable purification function.

[0015] (4) The addition of nano-calcium oxide particles to the surface of the photocatalyst layer of the present invention can effectively adsorb photocatalytic products (carbon dioxide and water), thereby eliminating the adverse effects of competitive adsorption between water vapor and formaldehyde particles caused by the strong hydrophilicity of molecular sieves, thus achieving the benefits of efficient and sustainable use. Attached Figure Description

[0016] Figure 1 A schematic diagram of a transparent sticker for sustainable formaldehyde purification; In the figure, 1 is the transparent substrate layer; 2 is the adhesive layer; 3 is the photocatalyst layer; and 4 is the adsorption layer. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Example 1 This invention provides a transparent formaldehyde-purifying material and its preparation method, the specific steps of which are as follows: (1) Take a PET film as the transparent substrate and coat it with a 40 μm thick medical non-toxic acrylate coating layer; (2) Add HCl to a soluble nano carbon nitride solution to prepare a 20 μm thick nano carbon nitride sol-gel film layer; (3) After magnetically stirring 10 g of CaO with 25 ml of ethanol as the solvent for 35 minutes, spray it evenly onto the surface of the photocatalyst layer and dry it for 100 minutes; (4) Prepare a 20% concentration of MCM-41 molecular sieve, 13X molecular sieve and 5A molecular sieve with water as the solvent by magnetic stirring for 30 minutes. mol / L molecular sieve mother liquor; (5) Using polymer precursor membrane as substrate carrier, the carrier is first immersed in 5A type molecular sieve mother liquor by in-situ hydrothermal synthesis method, heated at 100°C for 4 hours in an inert atmosphere, taken out, and coated with casting liquid with a mass fraction of 14% on the surface of the carrier to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting liquid film formation method is used to impregnate 13X and MCM-41 type molecular sieve mother liquor in sequence to form a film, so that the three types of molecular sieve crystal particles grow into films on the surface of the carrier in sequence, wrapping the surface of the photocatalyst layer and connecting with the acrylic ester adhesive layer. After standing for 2 hours, a transparent sticker that can continuously purify formaldehyde is obtained.

[0019] The PET film in this invention example has a thickness of 150 μm, a light transmittance of more than 90%, and a haze of less than 2%.

[0020] In this invention, the carbon nitride particles have a diameter of 13 nm and the carbon nitride solution concentration is 0.75 g / L.

[0021] In this embodiment of the invention, the thickness of the CaO solution sprayed onto the surface of the photocatalyst layer is 15 μm.

[0022] The molecular sieve adsorption film in this invention example has a thickness of 40 μm.

[0023] The casting solution in this invention uses dimethyl sulfoxide, triethyl phosphate and dimethylacetamide as its main components.

[0024] The molecular screening examples in this invention use synthetic mesoporous molecular sieves MCM-41, 13X type, and 5A type molecular sieves, whose specific surface areas are respectively 1000 m². 2 / g、450 m 2 / g、350 m 2 / g, with pore sizes of 2.5 nm, 1.0 nm, and 0.5 nm respectively. Among them, MCM-41 molecular sieve and 13X type molecular sieve need to be sieved through 200 mesh, heat-treated in an oven at 150 ℃ for 5 hours, and activated at 400 ℃ for 2 hours for pretreatment. 5A type molecular sieve only needs to be sieved through 200 mesh and does not need to be calcined.

[0025] The photocatalytic formaldehyde removal efficiency of the obtained transparent sticker that can continuously purify formaldehyde was evaluated. The efficiency of photocatalytic removal of formaldehyde air pollutants from decoration furniture was as high as 99.6%, and the efficiency after 20 cycles of testing was 87.2%, which is nearly 4 times higher than the formaldehyde removal efficiency and removal rate of other methods.

[0026] Example 2 This invention provides a transparent formaldehyde-purifying material and its preparation method, the specific steps of which are as follows: (1) Take a PET film as the transparent substrate and coat it with a 35 μm thick medical non-toxic acrylate coating layer; (2) Add HCl to a soluble nano carbon nitride solution to prepare a 15 μm thick nano carbon nitride sol-gel film layer; (3) Stir 10 g of CaO with 25 ml of ethanol as solvent magnetically for 35 minutes, then spray it evenly onto the surface of the photocatalyst layer and dry it for 100 minutes; (4) Prepare a 15% concentration of MCM-41 molecular sieve, 13X molecular sieve and 5A molecular sieve with water as solvent by magnetic stirring for 30 minutes. mol / L molecular sieve mother liquor; (5) Using polymer precursor membrane as substrate carrier, the carrier is first immersed in 5A type molecular sieve mother liquor by in-situ hydrothermal synthesis method, heated at 100°C for 4 hours in an inert atmosphere, taken out, and coated with casting liquid with a mass fraction of 10% on the surface of the carrier to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting liquid film formation method is used to impregnate 13X and MCM-41 type molecular sieve mother liquor in sequence to form a film, so that the three types of molecular sieve crystal particles grow into films on the surface of the carrier in sequence, wrapping the surface of the photocatalyst layer and connecting with the acrylic ester adhesive layer. After standing for 2 hours, a transparent sticker that can continuously purify formaldehyde is obtained.

[0027] The PET film in this invention example has a thickness of 100 μm, a light transmittance of more than 90%, and a haze of less than 2%.

[0028] In this invention, the carbon nitride particles have a diameter of 10 nm and the carbon nitride solution concentration is 0.75 g / L.

[0029] In this embodiment of the invention, the thickness of the CaO solution sprayed onto the surface of the photocatalyst layer is 10 μm.

[0030] The molecular sieve adsorption film in this invention example has a thickness of 30 μm.

[0031] The casting solution in this invention uses dimethyl sulfoxide, triethyl phosphate and dimethylacetamide as its main components.

[0032] The molecular screening examples in this invention use synthetic mesoporous molecular sieves MCM-41, 13X type, and 5A type molecular sieves, whose specific surface areas are respectively 900 m². 2 / g、400 m 2 / g、300 m2 / g, with pore sizes of 2.0 nm, 0.8 nm, and 0.5 nm respectively. Among them, MCM-41 molecular sieve and 13X type molecular sieve need to be sieved through 200 mesh, heat-treated in an oven at 150℃ for 5 hours, and activated at 400℃ for 2 hours for pretreatment. 5A type molecular sieve only needs to be sieved through 200 mesh and does not need to be calcined.

[0033] The photocatalytic formaldehyde removal efficiency of the obtained transparent sticker that can continuously purify formaldehyde was evaluated. Its efficiency in removing formaldehyde air pollutants from decoration furniture was 89%, and the efficiency was 80% after 20 cycles of testing.

[0034] Comparative Example 1 An example of this invention is a transparent formaldehyde-purifying patch and its preparation method, the specific steps of which are as follows: (1) Take PET film as the transparent substrate, and coat it with a 40 μm thick medical non-toxic acrylate coating layer; (2) Stir 10 g of CaO with 25 ml of ethanol as the solvent magnetically for 35 minutes, then spray it evenly onto the surface of the substrate layer and dry it for 100 minutes; (3) Prepare a 20% concentration by stirring MCM-41 molecular sieve, 13X molecular sieve and 5A molecular sieve with water as the solvent magnetically for 30 minutes. mol / L molecular sieve mother liquor; (4) Using polymer precursor membrane as substrate carrier, the carrier is first immersed in 5A type molecular sieve mother liquor by in-situ hydrothermal synthesis method, heated at 100°C for 4 hours in an inert atmosphere, taken out, and coated with casting liquid with a mass fraction of 14% on the surface of the carrier to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting liquid film formation method is used to impregnate 13X and MCM-41 type molecular sieve mother liquor in sequence to form a film, so that the three types of molecular sieve crystal particles grow into films on the surface of the carrier in sequence, wrapping the surface of the photocatalyst layer and connecting with the acrylic ester adhesive layer. After standing for 2 hours, a transparent sticker that can continuously purify formaldehyde is obtained.

[0035] The PET film in this invention example has a thickness of 150 μm, a light transmittance of more than 90%, and a haze of less than 2%.

[0036] In this example, the thickness of the CaO solution sprayed onto the surface of the transparent substrate is 15 μm.

[0037] The molecular sieve adsorption film in this invention example has a thickness of 40 μm.

[0038] The casting solution in this invention uses dimethyl sulfoxide, triethyl phosphate and dimethylacetamide as its main components.

[0039] The molecular screening examples in this invention use synthetic mesoporous molecular sieves MCM-41, 13X type, and 5A type molecular sieves, whose specific surface areas are respectively 1000 m². 2 / g、450 m 2 / g、350 m 2 / g, with pore sizes of 2.5 nm, 1.0 nm, and 0.5 nm respectively. Among them, MCM-41 molecular sieve and 13X type molecular sieve need to be sieved through 200 mesh, heat-treated in an oven at 150 ℃ for 5 hours, and activated at 400 ℃ for 2 hours for pretreatment. 5A type molecular sieve only needs to be sieved through 200 mesh and does not need to be calcined.

[0040] The photocatalytic formaldehyde removal efficiency of the obtained transparent formaldehyde-purifying sticker was evaluated. The efficiency of photocatalytic removal of formaldehyde air pollutants from decoration furniture was 80.3%, and the efficiency was only 18.4% after 20 cycles of testing.

[0041] As shown in Example 1 and Comparative Example 1, the formaldehyde-purifying transparent patch containing a nano-carbon nitride sol-gel film layer has a higher formaldehyde purification efficiency than the transparent patch with only an adsorption layer and CaO. Furthermore, its efficiency decreases more significantly after cyclic testing, lacking the benefits of repeated and sustainable use. This is mainly attributed to the visible light responsiveness of the nano-carbon nitride sol in the photocatalytic layer. After adsorbing formaldehyde in the adsorption layer, it undergoes a photocatalytic effect under sunlight, degrading formaldehyde into carbon dioxide and water. The transparent patch, after adsorption saturation, exhibits good regeneration performance after photocatalysis and can be reused multiple times.

[0042] Comparative Example 2 This invention provides a transparent formaldehyde-purifying material and its preparation method, the specific steps of which are as follows: (1) Take a PET film as the transparent substrate and coat it with a 35 μm thick medical non-toxic acrylate coating layer; (2) Add HCl to a soluble nano carbon nitride solution to prepare a 15 μm thick nano carbon nitride sol-gel film layer; (3) After magnetically stirring 10 g of CaO with 25 ml of ethanol as the solvent for 35 minutes, spray it evenly onto the surface of the photocatalyst layer and dry it for 100 minutes; (4) Prepare a 15% concentration of MCM-41 artificially synthesized mesoporous molecular sieve with water as the solvent by magnetic stirring for 30 minutes. (5) Using a polymer precursor membrane as a substrate carrier, the carrier is immersed in the molecular sieve mother liquor by in-situ hydrothermal synthesis method, heated at 100°C for 4 hours in an inert atmosphere, taken out, and coated with a casting liquid of 10% by mass on the surface of the carrier to form a film, so that the molecular sieve crystal particles grow on the surface of the carrier to form a film, which is wrapped on the surface of the photocatalyst layer and connected to the acrylic adhesive layer. After standing for 2 hours, a transparent sticker that can continuously purify formaldehyde is obtained.

[0043] The PET film in this invention example has a thickness of 100 μm, a light transmittance of more than 90%, and a haze of less than 2%.

[0044] In this invention, the carbon nitride particles have a diameter of 10 nm and the carbon nitride solution concentration is 0.75 g / L.

[0045] In this embodiment of the invention, the thickness of the CaO solution sprayed onto the surface of the photocatalyst layer is 10 μm.

[0046] The molecular sieve adsorption film in this invention example has a thickness of 30 μm.

[0047] The casting solution in this invention uses dimethyl sulfoxide, triethyl phosphate and dimethylacetamide as its main components.

[0048] The molecular sieve used in this invention example is a synthetic mesoporous molecular sieve, MCM-41, with a specific surface area of ​​900 m². 2 / g, with a pore size of 2.0 nm, and requires pretreatment including 200-mesh sieve, heat treatment at 150 ℃ in an oven for 5 hours, and activation at 400 ℃ for 2 hours.

[0049] The photocatalytic formaldehyde removal efficiency of the obtained transparent sticker that can continuously purify formaldehyde was evaluated. Its efficiency in removing formaldehyde air pollutants from decoration furniture was 72.6%, and the efficiency after 20 cycles was 63.8%.

[0050] As shown in Example 2 and Comparative Example 2, the transparent film made using only one type of molecular sieve membrane exhibits lower formaldehyde adsorption efficiency compared to the transparent film using three different molecular sieves with varying pore sizes and specific surface areas to form a multi-layer molecular sieve adsorption layer. This effect is more pronounced during initial use. This is mainly attributed to the use of three different types of molecular sieves to form a composite membrane, with pore sizes and specific surface areas decreasing sequentially from the outside to the inside. This creates a multi-layer molecular structure with narrow, elongated pore channels, which facilitates the diffusion of formaldehyde gas molecules within the molecular sieve. The strong Coulomb forces allow formaldehyde particles to be efficiently adsorbed layer by layer and diffused into the pores within the adsorption layer, thus achieving highly efficient and precise adsorption.

[0051] Comparative Example 3 An example of this invention is a transparent formaldehyde-purifying patch and its preparation method, the specific steps of which are as follows: (1) Take a PET film as the transparent substrate and coat it with a 35 μm thick medical non-toxic acrylate coating layer; (2) Add HCl to a soluble nano carbon nitride solution to prepare a 15 μm thick nano carbon nitride sol-gel film layer; (3) Mix MCM-41 molecular sieve, 13X molecular sieve and 5A molecular sieve with water as solvent and stir magnetically for 30 minutes to prepare a solution with a concentration of 15 mol / L molecular sieve mother liquor; (4) Using polymer precursor membrane as substrate carrier, the carrier is first immersed in 5A type molecular sieve mother liquor by in-situ hydrothermal synthesis method, heated at 100°C for 4 hours in an inert atmosphere, taken out, and coated with casting liquid with a mass fraction of 10% on the surface of the carrier to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting liquid film formation method is used to impregnate 13X and MCM-41 type molecular sieve mother liquor in sequence to form a film, so that the three types of molecular sieve crystal particles grow into films on the surface of the carrier in sequence, wrapping the surface of the photocatalyst layer and connecting with the acrylic ester adhesive layer. After standing for 2 hours, a transparent sticker that can continuously purify formaldehyde is obtained.

[0052] The PET film in this invention example has a thickness of 100 μm, a light transmittance of more than 90%, and a haze of less than 2%.

[0053] In this invention, the carbon nitride particles have a diameter of 10 nm and the carbon nitride solution concentration is 0.75 g / L.

[0054] The molecular sieve adsorption film in this invention example has a thickness of 30 μm.

[0055] The casting solution in this invention uses dimethyl sulfoxide, triethyl phosphate and dimethylacetamide as its main components.

[0056] The molecular screening examples in this invention use synthetic mesoporous molecular sieves MCM-41, 13X type, and 5A type molecular sieves, whose specific surface areas are respectively 900 m². 2 / g、400 m 2 / g、300 m 2 / g, with pore sizes of 2.0 nm, 0.8 nm, and 0.5 nm respectively. Among them, MCM-41 molecular sieve and 13X type molecular sieve need to be sieved through 200 mesh, heat-treated in an oven at 150 ℃ for 5 hours, and activated at 400 ℃ for 2 hours for pretreatment. 5A type molecular sieve only needs to be sieved through 200 mesh and does not need to be calcined.

[0057] The photocatalytic formaldehyde removal efficiency of the obtained transparent sticker that can continuously purify formaldehyde was evaluated. Its efficiency in removing formaldehyde air pollutants from decoration furniture was 65%, and the efficiency after 20 cycles was 21.6%.

[0058] As shown in Example 2 and Comparative Example 3, the formaldehyde adsorption efficiency of the transparent sticker containing CaO is lower than that of the transparent sticker without a drying layer, and the impact on recycling is more significant. This is mainly attributed to the fact that after the photocatalytic layer performs a photocatalytic reaction on formaldehyde, it degrades formaldehyde into water and carbon dioxide. However, the molecular sieve in the adsorption layer has strong hydrophilicity, causing water molecules to compete with formaldehyde molecules for adsorption and affecting the adhesiveness of the transparent sticker, resulting in a significant reduction in the formaldehyde adsorption content and a decrease in adsorption efficiency. The addition of CaO to the surface of the photocatalytic layer can effectively enrich the H2O and CO2 produced by photocatalytic degradation, thereby eliminating the adverse effects of competitive adsorption between water vapor and formaldehyde particles caused by the strong hydrophilicity of the molecular sieve, thus achieving the benefits of efficient and sustainable use.

[0059] The applicant declares that the detailed composition and method of this invention are illustrated through the above embodiments, but this invention is not limited to the detailed composition and method described above, that is, it does not mean that this invention must rely on the detailed composition and method described above to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials in the product of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A transparent sticker for sustainable formaldehyde purification, characterized in that, It includes a transparent substrate layer (1), an adhesive layer (2), a photocatalyst layer (3), and an adsorption layer (4); The upper surface of the transparent substrate layer (1) consists of an adhesive layer (2), a photocatalyst layer (3), and an adsorption layer (4) in sequence.

2. The transparent sticker for sustainable formaldehyde purification according to claim 1, characterized in that, The transparent substrate layer (1) is a PET film layer with a thickness of 100~200 μm, a light transmittance of more than 90%, and a haze of less than 2%.

3. The transparent sticker for sustainable formaldehyde purification according to claim 1, characterized in that, The adhesive layer (2) is a medical non-toxic acrylic coating layer, which is the same type of adhesive used in medical bandages, and its thickness is 35~45 μm.

4. The transparent sheet for sustainable formaldehyde purification according to claim 1, characterized in that, The photocatalyst layer (3) is composed of nano carbon nitride sol-gel film and nano calcium oxide, and the thickness of the photocatalyst layer (3) is 15~20 μm.

5. The transparent sticker for sustainable formaldehyde purification according to claim 4, characterized in that, The nano-carbon nitride sol-gel film has a nano-carbon nitride particle size of 10±3 nm and is prepared by adding a strong acid to a 0.75 g / L completely soluble nano-carbon nitride solution.

6. The transparent sheet for sustainable formaldehyde purification according to claim 4, characterized in that, 10-15 g of nano-calcium oxide particles with a particle size of 10-80 nm were uniformly dispersed in 20-25 ml of ethanol as an organic solvent for 30-40 minutes, and then uniformly sprayed onto the surface of nano-carbon nitride sol-gel film. After drying for 90-120 minutes, a photocatalyst layer was prepared (3).

7. The transparent sticker for sustainable formaldehyde purification according to claim 1, characterized in that, The adsorption layer (4) is a molecular sieve adsorption film, wherein the molecular sieve is selected from artificial synthetic mesoporous molecular sieve MCM-41, 13X type and 5A type molecular sieve, the specific surface area is 900-1000 m 2 / g, 400-500 m 2 / g, 300-400 m 2 / g, the pore size is 2-5 nm, 1 nm, 0.5 nm, respectively, and the thickness of the adsorption layer (4) is 30-40 μm.

8. A transparent sheet for sustainable formaldehyde purification according to claim 7, characterized in that, MCM-41 and 13X molecular sieves require 200-mesh sieving, oven heat treatment at 150-200℃ for 5-6 hours, and activation at 400℃ for 2-3 hours as a pretreatment. 5A molecular sieves only require 200-mesh sieving and do not require calcination to prevent crystallization.

9. A transparent sheet for sustainable formaldehyde purification according to claim 7, characterized in that, The molecular sieve adsorption film uses a polymer precursor film containing a transparent substrate layer, an adhesive layer, and a photocatalyst layer as a substrate carrier. Three types of molecular sieves are prepared by mixing water as a solvent and magnetically stirring for 30-45 minutes to prepare a molecular sieve mother liquor with a concentration of 15-30 mol / L. Using an in-situ hydrothermal synthesis method, the carrier is first immersed in the 5A type molecular sieve mother liquor and heated at 100°C for 2-5 hours in an inert atmosphere. After removal, a casting solution with a mass fraction of 14% is coated onto the carrier surface to form a film. Subsequently, the same in-situ hydrothermal impregnation combined with casting solution film formation method is used to sequentially impregnate 13X and MCM-41 type molecular sieve mother liquors to form films. This allows the three types of molecular sieve crystal particles to grow sequentially on the carrier surface, forming films that are then wrapped around the surface of the photocatalyst layer and connected to the adhesive layer.

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