Environment-friendly water-based paint with function of removing formaldehyde through reaction and preparation method of environment-friendly water-based paint

Abstract

The invention discloses an environment-friendly water-based coating with a function of removing formaldehyde through reaction and a preparation method of the environment-friendly water-based coating. The coating comprises the following components in parts by mass: 30-50 parts of water-based acrylic resin, 5-15 parts of a composite formaldehyde remover, 0.5-2 parts of a dispersing agent, 0.1-0.5 part of a defoaming agent, 0.2-1 part of a flatting agent, 10-20 parts of filler and deionized water. The composite formaldehyde remover is composed of carboxymethyl chitosan, CeO2: Yb nanofibers and hydroxypropyl beta-cyclodextrin, efficient and lasting formaldehyde removal is achieved through the synergistic effect of physical adsorption, chemical reaction and normal-temperature catalysis, and the removal rate reaches 90-95% within 24 hours and reaches 75-82% after 180 days. The preparation method comprises the steps of resin mixing, remover dispersing and pH adjusting and filtering, and is simple in process, excellent in film coating performance, high in water resistance, suitable for industrial production, green and environmentally friendly, and the adhesive force is 1-2 levels.

Description

Technical Field

[0001] The present invention relates to the technical field of environmentally friendly water-based coatings, and in particular to an environmentally friendly water-based coating with the function of removing formaldehyde by reaction and a preparation method thereof. Background Art

[0002] In recent years, with increasing attention paid to the impact of indoor air quality on human health, environmentally friendly water-based paints have become the preferred material for architectural decoration due to their low volatile organic compound (VOC) emissions and environmentally friendly properties. To address the problem of indoor formaldehyde pollution, various formaldehyde removal strategies have been developed, primarily including physical adsorption, chemical reaction, and photocatalytic decomposition. Physical adsorption utilizes high-surface-area materials such as activated carbon, zeolites, or diatomaceous earth to capture formaldehyde molecules through van der Waals forces or capillary action. Chemical reaction techniques employ amine compounds (such as polyethyleneimine) to form stable Schiff bases or imine compounds with formaldehyde for irreversible removal. Photocatalytic techniques utilize semiconductor materials such as TiO2 and ZnO to generate reactive oxygen species under light, oxidizing formaldehyde to carbon dioxide and water. Furthermore, some studies have explored emerging methods such as enzyme-catalyzed degradation (such as formaldehyde dehydrogenase) and ambient-temperature catalytic oxidation using metal oxides (such as MnO2). These techniques have demonstrated promising formaldehyde removal results under laboratory conditions and have promoted the development of functional water-based paints. However, the long-term performance and industrial feasibility of existing technologies in practical applications still have many limitations, and further optimization is urgently needed to meet the market demand for efficient and long-lasting formaldehyde removal.

[0003] Although the above technologies have made certain progress in formaldehyde removal, their ability to continuously and efficiently capture and decompose formaldehyde in long-term use still faces significant challenges. First, physical adsorption materials are prone to adsorption saturation due to limited adsorption sites, resulting in a decrease in formaldehyde removal efficiency over time, and lack an effective regeneration mechanism. Secondly, although chemical reaction materials have a high initial removal efficiency, the active components (such as amino groups) may be exhausted during long-term use due to reactions with formaldehyde or other environmental factors, or lose their activity due to the surface being covered by the polymer matrix after the coating film is formed, significantly reducing the sustainability of the function. Photocatalytic technology is limited by lighting conditions (such as low-light environment indoors) and the uniformity of the dispersion of the catalyst in the coating matrix, making it difficult to ensure a stable decomposition efficiency. In addition, the existing technology is insufficient in terms of taking into account both the formaldehyde removal function and the basic properties of the coating (such as film forming, adhesion, and durability). The introduction of functional components often leads to a decrease in the viscosity, stability or construction performance of the coating system. While bio-enzymes and metal oxide catalysts hold promise, their high cost, environmental sensitivity (e.g., deactivation due to temperature and humidity fluctuations), and compatibility issues with water-based coating systems have limited their widespread application. Therefore, there is an urgent need to develop environmentally friendly water-based coatings that can continuously and efficiently capture and decompose formaldehyde over long-term use without losing effectiveness due to active component depletion or surface coverage, thereby achieving a synergistic optimization of functionality and practicality. Summary of the Invention

[0004] The present application provides an environmentally friendly water-based coating with the function of reactive formaldehyde removal, which comprises, by weight: 30 to 50 parts of water-based acrylic resin, 5 to 15 parts of composite formaldehyde remover, 0.5 to 2 parts of dispersant, 0.1 to 0.5 parts of defoaming agent, 0.2 to 1 part of leveling agent, and 10 to 20 parts of filler;

[0005] The preparation steps of the composite formaldehyde remover include: first, dissolving food-grade chitosan in a 2% acetic acid solution, adding chloroacetic acid, stirring at 60°C for 6 hours to perform carboxymethylation, precipitating with ethanol, washing, and vacuum drying at 80°C for 8 hours to obtain carboxymethyl chitosan; second, preparing a spinning solution by combining cerium nitrate and ytterbium nitrate with 10wt% polyvinyl alcohol, electrospinning at 15kV, immersing in a 5wt% CMCS solution for 2 hours, and calcining at 600°C for 2 hours to load CeO2:Yb nanofibers; finally, dissolving β-cyclodextrin in 0.1mol / L sodium hydroxide, adding propylene oxide, reacting at 50°C for 4 hours to obtain HP-β-CD, dispersing CeO2:Yb / CMCS in the 5wt% HP-β-CD solution, stirring for 4 hours, drying at 60°C, mixing in a ratio of 2:2:1, and stirring at 1000rpm for 30 minutes.

[0006] It is important to note that, first, CMCS is rich in carboxyl and amino groups. The carboxyl groups physically adsorb formaldehyde molecules through hydrogen bonding and van der Waals forces, while the amino groups undergo a nucleophilic addition reaction with formaldehyde to form a stable Schiff base, enabling irreversible chemical capture and reducing the risk of active site depletion. Second, the CeO2:Yb nanofibers, through ytterbium doping, introduce abundant surface oxygen vacancies, catalyzing the oxidation of formaldehyde to carbon dioxide and water at room temperature. The nanofiber structure provides a high specific surface area, enhancing catalytic efficiency and adapting to low-light indoor environments, thus avoiding the dependence of photocatalytic technology on illumination. Finally, the hydroxypropylated cavity structure of HP-β-CD selectively captures formaldehyde molecules through supramolecular inclusion complexation, forming a host-guest complex and transferring them to CMCS for chemical reaction or CeO2:Yb for catalytic decomposition, thus extending the life of the adsorption sites. The synergistic effect of the three components ensures rapid capture, chemical immobilization, and sustained decomposition of formaldehyde. Furthermore, the molecular network structure of HP-β-CD and CMCS enhances resistance to surface coverage and maintains long-term functional activity.

[0007] Preferably, the dispersant is sodium polycarboxylate or ammonium polyacrylate.

[0008] Preferably, the defoaming agent is a non-ionic silicone defoaming agent.

[0009] Preferably, the leveling agent is polyether-modified polydimethylsiloxane.

[0010] Preferably, the filler is selected from one or more of calcium carbonate, talc or kaolin.

[0011] A method for preparing an environmentally friendly water-based paint comprises the following technical steps:

[0012] Step 1. Add 30-50 parts of water-based acrylic resin, 0.5-2 parts of dispersant, 0.1-0.5 parts of defoamer, 0.2-1 parts of leveling agent and the balance of deionized water to a stirring tank, stir at 500-1000rpm for 30-60 minutes until uniform, slowly add 10-20 parts of filler, stir at 1000-1500rpm for 30-60 minutes, no agglomeration;

[0013] Step 2. Add 5-15 parts of the composite formaldehyde remover to the mixed system in batches and disperse at a high speed of 2000-3000rpm for 30-60 minutes to ensure uniform distribution of the functional components;

[0014] Step 3. Adjust the pH to 7-9 with ammonia or citric acid, filter through a 200-400 mesh filter to remove impurities, and obtain the final coating.

[0015] It should be noted that in step 1, water-based acrylic resin (30-50 parts) is used as a matrix to provide film-forming properties and durability, dispersant (0.5-2 parts), defoamer (0.1-0.5 parts) and leveling agent (0.2-1 parts) optimize the uniformity and stability of the system by reducing surface tension, inhibiting bubbles and improving fluidity; deionized water is used to adjust the viscosity, and stirring is performed at 500-1000 rpm for 30-60 minutes to ensure that the components are fully mixed. Filler (10-20 parts, such as calcium carbonate) is stirred at 1000-1500 rpm for 30-60 minutes to be evenly dispersed, thereby enhancing mechanical properties and hiding power, avoiding agglomeration and providing a uniform matrix for subsequent functional components. In step 2, a composite formaldehyde remover (5-15 parts) is added in batches and dispersed at a high speed of 2000-3000rpm for 30-60 minutes to ensure that it is evenly embedded in the resin matrix; the remover contains carboxymethyl chitosan (CMCS, physical adsorption and chemical reaction to form Schiff base), CeO2: Yb nanofibers (catalytic oxidation of formaldehyde to carbon dioxide and water at room temperature) and HP-β-CD (supramolecular inclusion capture of formaldehyde). The three work synergistically to achieve rapid capture, irreversible fixation and continuous decomposition, preventing active site depletion or surface coverage. In step 3, ammonia water or citric acid is used to adjust the pH to 7-9 to optimize the chemical stability of the system, and a 200-400 mesh filter is used to remove impurities to ensure the quality of the coating and the activity of the functional components. This step-by-step process forms a multi-level network structure through interface interaction and dispersion optimization, enhancing formaldehyde removal efficiency and anti-covering ability.

[0016] The environmentally friendly water-based paint provided by the present invention exhibits significant beneficial effects through a composite formaldehyde remover (CMCS, CeO2:Yb, HP-β-CD, mass ratio of 2:2:1) and an optimized preparation process: the formaldehyde removal rate reaches 90-95% in 24 hours and still maintains 75-82% after 180 days, far exceeding that of traditional single adsorption or catalytic materials; the physical adsorption and chemical reaction of CMCS, the room-temperature catalysis of CeO2:Yb, and the supramolecular inclusion of HP-β-CD synergistically ensure rapid capture, irreversible fixation, and continuous decomposition of formaldehyde, effectively overcoming the problems of active component exhaustion and surface coverage; the paint has adhesion of 1-2 levels, excellent water resistance, and a coating film smoothness Ra value of 0.3-0.5μm, taking into account both construction performance; CeO2:Yb is adaptable to low-light environments, and CMCS and HP-β-CD have strong environmental stability and are applicable to various scenarios; biomass raw materials are used, the product is green and environmentally friendly, the preparation process is simple, suitable for industrial production, and has excellent comprehensive performance. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0018] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive with other embodiments.

[0020] Example

[0021] Example 1

[0022] Components (parts by mass): 40 parts of water-based acrylic resin (solid content 45wt%, molecular weight 80,000), 10 parts of composite formaldehyde remover, 1 part of sodium polycarboxylate dispersant, 0.3 parts of non-ionic silicone defoamer, 0.5 parts of polyether modified polydimethylsiloxane leveling agent, 15 parts of calcium carbonate filler (particle size 10μm), and the balance of deionized water.

[0023] Preparation of composite formaldehyde remover: First, food-grade chitosan (molecular weight 150,000) was dissolved in 2% acetic acid solution (solid-liquid ratio 1:20), chloroacetic acid (mass ratio 1:2) was added, stirred at 60°C for 6 hours, ethanol precipitated, and vacuum dried at 80°C for 8 hours to obtain CMCS (carboxyl substitution degree 1.0); secondly, cerium nitrate and ytterbium nitrate (molar ratio 10:1) were mixed with 10wt% polyvinyl alcohol to prepare a spinning solution, electrospun at 15kV, and immersed in 5wt% CMCS solution. 2 hours, calcined at 600℃ for 2 hours, loaded with CeO2:Yb nanofibers (diameter 100nm); finally, β-cyclodextrin was dissolved in 0.1mol / L sodium hydroxide, propylene oxide (molar ratio 1:2) was added, and reacted at 50℃ for 4 hours to obtain HP-β-CD, and CeO2:Yb / CMCS was dispersed in 5wt% HP-β-CD solution, stirred for 4 hours, dried at 60℃, mixed in 2:2:1 ratio, and stirred at 1000rpm for 30 minutes.

[0024] Preparation process: Step 1: Stir the resin, dispersant, defoamer, leveling agent and deionized water at 800 rpm for 40 minutes, add the filler and stir at 1200 rpm for 40 minutes; Step 2: Add the remover in three batches and disperse at 2500 rpm for 40 minutes; Step 3: Adjust the pH to 8.0 with ammonia water and filter through a 300-mesh filter.

[0025] Example 2

[0026] Components (parts by mass): 45 parts of water-based acrylic resin (solid content 50wt%, molecular weight 70,000), 12 parts of composite formaldehyde remover, 1.2 parts of polyacrylate ammonium dispersant, 0.4 parts of non-ionic silicone defoamer, 0.6 parts of polyether modified polydimethylsiloxane leveling agent, 18 parts of talc and calcium carbonate (1:1, particle size 8μm), and the balance of deionized water.

[0027] Preparation of composite formaldehyde remover: Same as Example 1, except that the degree of substitution of CMCS carboxyl groups was adjusted to 1.1, the diameter of CeO2:Yb nanofibers was 80 nm, and the degree of substitution of HP-β-CD was 5.

[0028] Preparation process: Step 1: Stir at 900 rpm for 45 minutes, add filler at a rate of 0.5 kg / min, and stir at 1300 rpm for 45 minutes; Step 2: Add remover in four batches and disperse at 2800 rpm for 45 minutes; Step 3: Adjust pH to 7.5 with citric acid and filter with 350 mesh filter

[0029] Example 3

[0030] Components (parts by mass): 35 parts of water-based acrylic resin (solid content 42wt%, molecular weight 90,000), 8 parts of composite formaldehyde remover, 0.8 parts of sodium polycarboxylate dispersant, 0.2 parts of non-ionic silicone defoamer, 0.4 parts of polyether modified polydimethylsiloxane leveling agent, 12 parts of kaolin filler (particle size 12μm), and the balance of deionized water.

[0031] Preparation of composite formaldehyde remover: Same as Example 1, the ytterbium doping amount in CeO2:Yb was adjusted to 10 mol%, and the nanofiber diameter was 120 nm.

[0032] Preparation process: Step 1: Stir at 600 rpm for 50 minutes, and stir the filler at 1000 rpm for 50 minutes; Step 2: Add the remover in three batches and disperse at 2200 rpm for 50 minutes; Step 3: Adjust the pH to 8.5 with ammonia water and filter through a 400 mesh filter.

[0033] Example 4

[0034] Components (parts by mass): 50 parts of water-based acrylic resin (solid content 48wt%, molecular weight 60,000), 15 parts of composite formaldehyde remover, 1.5 parts of polyacrylate ammonium dispersant, 0.5 parts of non-ionic silicone defoamer, 0.8 parts of polyether modified polydimethylsiloxane leveling agent, 20 parts of calcium carbonate and kaolin (1:2, particle size 15μm), and the balance of deionized water.

[0035] Preparation of composite formaldehyde remover: Same as Example 1, except that the mass ratio of CMCS to chloroacetic acid was adjusted to 1:2.2, and the degree of substitution of HP-β-CD was 4.5.

[0036] Preparation process: Step 1: Stir at 1000 rpm for 30 minutes, and stir the filler at 1500 rpm for 30 minutes; Step 2: Add the remover in five batches and disperse at 3000 rpm for 30 minutes; Step 3: Adjust the pH to 7.8 with citric acid and filter through a 200-mesh filter.

[0037] Control Example

[0038] Comparative Example 1

[0039] Components (parts by mass): 40 parts of water-based acrylic resin, 1 part of sodium polycarboxylate dispersant, 0.3 parts of non-ionic silicone defoaming agent, 0.5 parts of polyether modified polydimethylsiloxane leveling agent, 15 parts of calcium carbonate filler, and the balance of deionized water (without composite formaldehyde remover).

[0040] Preparation process: Same as Example 1, but step 2 is omitted.

[0041] Comparative Example 2

[0042] Components (parts by mass): Same as Example 1, except that the composite formaldehyde remover contains only 10 parts of CMCS, and no CeO2:Yb and HP-β-CD.

[0043] Preparation process: Same as Example 1, except that only CMCS is added in step 2.

[0044] Comparative Example 3

[0045] Components (parts by mass): Same as Example 1, except that the composite formaldehyde remover contains only CMCS and HP-β-CD (mass ratio 2:1).

[0046] Preparation process: Same as Example 1, except that the CeO2:Yb step is omitted in the preparation of the remover.

[0047] Comparative Example 4

[0048] Components (parts by mass): Same as Example 1, except that the composite formaldehyde remover contains only CMCS and CeO2:Yb (mass ratio 2:2).

[0049] Preparation process: Same as Example 1, except that the HP-β-CD step is omitted in the preparation of the remover.

[0050] Performance testing methods

[0051] 1. Formaldehyde removal rate test:

[0052] Method: Refer to GB / T 34676-2017 and apply the coating to 100cm 2 Glass plate (coating thickness about 100μm), after curing for 24 hours, place it at 1m 3 Sealed cabin, initial formaldehyde concentration 1.0 mg / m 3, temperature 25±1°C, humidity 50±5%. After 24 hours and 180 days, formaldehyde concentration was measured by spectrophotometry (acetylacetone method), and the removal rate was calculated ([(initial concentration - residual concentration) / initial concentration] × 100%).

[0053] Equipment: Sealed cabin (1m 3 ), UV-visible spectrophotometer.

[0054] 2. Adhesion test:

[0055] Method: According to GB / T 9286-1998, draw a 6×6 grid (spacing 2mm), stick it with 3M tape, and then tear it off to assess the peeling level (0 is the best and 5 is the worst).

[0056] Equipment: grid marker, 3M tape.

[0057] 3. Water resistance test:

[0058] Method: According to GB / T 1733-1993, the coating film was immersed in 25℃ deionized water for 48 hours, and the blistering, shedding or discoloration was observed and rated as excellent (no change), good (slight change) or poor (obvious defects).

[0059] Equipment: Constant temperature water bath.

[0060] 4. Coating smoothness test:

[0061] Method: Use a surface roughness meter to measure the Ra value. Ra ≤ 0.5 μm is high smoothness, 0.5-1.0 μm is medium, and > 1.0 μm is low.

[0062] Equipment: Surface roughness tester

[0063] Table 1

[0064]

[0065]

[0066] Combining Examples 1 to 4 and Table 1, it can be seen that Examples 1-4 achieved a 24-hour formaldehyde removal rate of 90-95%, maintaining 75-82% after 180 days, surpassing Control Examples 1-4 (<5%-88% and <5%-65%). Adhesion was generally Grade 1 (Grade 2 for Example 3), water resistance was excellent (good for Example 3), and the coating smoothness Ra value was 0.3-0.5 μm, demonstrating excellent performance. The Examples utilize a composite formaldehyde remover (CMCS, CeO2:Yb, HP-β-CD, in a mass ratio of 2:2:1). Through the synergistic effects of CMCS's physical adsorption and chemical reaction, CeO2:Yb's ambient temperature catalysis, and HP-β-CD's supramolecular inclusion, the agents achieve rapid capture, irreversible fixation, and sustained decomposition of formaldehyde, while resisting surface coverage and activity depletion.

[0067] Combining Example 1, Comparative Examples 1 to 4, and Table 1, it can be seen that Example 1 achieved a 24-hour formaldehyde removal rate of 92% and 78% after 180 days, significantly superior to Comparative Example 1 (<5%), Comparative Example 2 (80% and 50%), Comparative Example 3 (85% and 60%), and Comparative Example 4 (88% and 65%). Adhesion was Grade 1, water resistance was excellent, and the coating smoothness Ra value was 0.4-0.5 μm (high smoothness), with minimal performance differences. Example 1 utilizes a composite formaldehyde remover (CMCS, CeO2:Yb, HP-β-CD, mass ratio 2:2:1). Through the synergistic effects of CMCS physical adsorption and chemical Schiff base formation, CeO2:Yb room-temperature catalytic oxidation, and HP-β-CD supramolecular inclusion, rapid, irreversible, and sustained formaldehyde removal was achieved, resisting surface coverage and activity depletion. Control Example 1 lacks a remover and has no function; Control Example 2 contains only CMCS, which is adsorbed and saturated, resulting in long-term failure; Control Example 3 does not have CeO2:Yb and lacks catalytic decomposition; Control Example 4 does not have HP-β-CD, and the capture efficiency is reduced, verifying the necessity of the three-component synergy and process optimization.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An environmentally friendly water-based paint with the function of removing formaldehyde by reaction, characterized in that: The components include, by mass: 30 to 50 parts of water-based acrylic resin, 5 to 15 parts of composite formaldehyde remover, 0.5 to 2 parts of dispersant, 0.1 to 0.5 parts of defoaming agent, 0.2 to 1 part of leveling agent and 10 to 20 parts of filler; The preparation steps of the composite formaldehyde remover include: first, dissolving food-grade chitosan in a 2% acetic acid solution, adding chloroacetic acid, stirring at 60°C for 6 hours to perform carboxymethylation, precipitating with ethanol, washing, and vacuum drying at 80°C for 8 hours to obtain carboxymethyl chitosan; second, preparing a spinning solution by combining cerium nitrate and ytterbium nitrate with 10wt% polyvinyl alcohol, electrospinning at 15kV, immersing in a 5wt% CMCS solution for 2 hours, and calcining at 600°C for 2 hours to load CeO2:Yb nanofibers; finally, dissolving β-cyclodextrin in 0.1mol / L sodium hydroxide, adding propylene oxide, reacting at 50°C for 4 hours to obtain HP-β-CD, dispersing CeO2:Yb / CMCS in the 5wt% HP-β-CD solution, stirring for 4 hours, drying at 60°C, mixing in a ratio of 2:2:1, and stirring at 1000rpm for 30 minutes.

2. The environmentally friendly water-based paint having the function of reactively removing formaldehyde according to claim 1, characterized in that: The dispersant is sodium polycarboxylate or ammonium polyacrylate.

3. The environmentally friendly water-based paint having the function of reactively removing formaldehyde according to claim 1, characterized in that: The defoamer is a nonionic silicone defoamer.

4. The environmentally friendly water-based paint having the function of reactively removing formaldehyde according to claim 1, characterized in that: The leveling agent is polyether-modified polydimethylsiloxane.

5. The environmentally friendly water-based paint having the function of reactively removing formaldehyde according to claim 1, characterized in that: The filler is selected from one or more of calcium carbonate, talc or kaolin.

6. The method for preparing the environmentally friendly water-based coating according to claim 1, characterized in that: The following technical steps are included: Step 1. Add 30-50 parts of water-based acrylic resin, 0.5-2 parts of dispersant, 0.1-0.5 parts of defoamer, 0.2-1 parts of leveling agent and the balance of deionized water to a stirring tank, stir at 500-1000rpm for 30-60 minutes until uniform, slowly add 10-20 parts of filler, stir at 1000-1500rpm for 30-60 minutes, no agglomeration; Step 2. Add 5-15 parts of the composite formaldehyde remover to the mixed system in batches and disperse at a high speed of 2000-3000rpm for 30-60 minutes to ensure uniform distribution of the functional components; Step 3. Adjust the pH to 7-9 with ammonia or citric acid, filter through a 200-400 mesh filter to remove impurities, and obtain the final coating.

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