Antibacterial coating and method for wood product surface treatment

Abstract

The invention relates to an antibacterial coating for wood product surface treatment and a method, and belongs to the technical field of coatings. The preparation method of the antibacterial coating for wood product surface treatment comprises the following steps: in a nitrogen gas environment, preheating isocyanate, adding a solvent, a polymerization inhibitor and an organic tin catalyst, mixing, adding polyol, carrying out a stirring reaction, and carrying out rotary evaporation to remove the solvent so as to obtain a prepolymer; and putting the prepolymer, the pigment, the mixed monomer and the photoinitiator into a reaction kettle, heating, stirring, grinding and filtering to obtain the photoinitiator. The coating prepared by the invention has strong adhesive force in wood products, can adapt to the porous and high-hydroxyl characteristics of wood, has a multi-component synergistic antibacterial property, has excellent and lasting antibacterial performance, can effectively protect the wood products from being eroded by microorganisms, and keeps stable interface bonding for a long time.

Description

Technical Field

[0001] This invention belongs to the technical field of coatings, and relates to an antibacterial coating and method for surface treatment of wood products. Background Technology

[0002] Polyurethane coatings for wood products use polyurethane resin as the main film-forming component. The film-forming principle involves a cross-linking reaction between the hydroxyl and isocyanate groups in the polyurethane resin, forming a continuous, dense film that combines flexibility and hardness. Simultaneously, the coating can effectively penetrate the tiny pores on the wood surface, forming a physical bond with the wood fibers. These coatings are widely used in the wood products industry, covering furniture, solid wood flooring, wooden doors, and wooden handicrafts. They possess excellent decorative properties, allowing for the formulation of matte, semi-matte, and glossy finishes, as well as a variety of colors to suit various style requirements. They also provide comprehensive protection for the wood: resisting scratches and friction from daily use, preventing moisture, water stains, and dirt penetration, delaying shrinkage, expansion, or cracking caused by temperature and humidity changes, and reducing the aging effects of ultraviolet radiation on the wood color, thus extending the appearance preservation period and overall lifespan of wood products.

[0003] The adhesion of polyurethane coatings for wood products is the core foundation for ensuring their functionality. Only with good adhesion can the coating adhere tightly to the porous and fibrous surface of the wood, preventing peeling and flaking due to wiping, collision, or changes in temperature and humidity during daily use. This provides long-term protection against moisture, stains, and friction, maintaining the decorative properties of the coating and its protective function against the wood, preventing direct exposure and damage. The antibacterial properties target the characteristics of wood, which easily absorbs moisture and dust, leading to the growth of microorganisms. It can effectively inhibit the growth and reproduction of bacteria and mold, preventing the wood from developing black spots, odors, or even fiber decomposition (reducing strength) due to mold. It can also reduce the health risks such as respiratory discomfort and skin allergies caused by the spread of microorganisms, making it especially suitable for high-frequency contact or humid environments such as kitchens, bathrooms, and children's furniture. Summary of the Invention

[0004] The purpose of this invention is to provide an antibacterial coating and method for surface treatment of wood products. The coating prepared by this invention has strong adhesion to wood products, can adapt to the porous and high hydroxyl characteristics of wood, and has synergistic antibacterial properties of multiple components. Its antibacterial performance is excellent and long-lasting, and can effectively protect wood products from microbial erosion and maintain a stable interface bond for a long time.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing an antibacterial coating for wood product surface treatment includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate, add solvent, polymerization inhibitor and organotin catalyst and mix, add polyol and stir to react, remove the solvent by rotary evaporation to obtain the prepolymer; Step 2: Place the prepolymer, pigment, nano silver, mixed monomers and photoinitiator in a reaction vessel, heat and stir, grind, and filter to complete the preparation.

[0006] As a preferred embodiment of the present invention, the preheating temperature in step one is 50-60℃, the stirring reaction temperature is 60-70℃ and the reaction time is 4-5h, the solvent is ethyl acetate, the polymerization inhibitor is 2,6-di-tert-butyl-p-cresol, the organotin catalyst is organotin catalyst T12, dibutyltin dilaurate, and the polyol is polyether polyol DL-2000 with a functionality of 2.

[0007] As a preferred embodiment of the present invention, the mass ratio of isocyanate, solvent, organotin catalyst, polymerization inhibitor and polyol in step one is 60-70:35-42:0.02-0.03:0.015-0.018:20-24; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:1.

[0008] As a preferred embodiment of the present invention, in step two, the mass ratio of the prepolymer, pigment, nano-silver, mixed monomer, and photoinitiator is 52-64:16-21:1.8-2.2:120-135:4.2-5.0. The pigment is Colanyl water-based titanium white pigment TQ 100-CN. The mixed monomer is composed of Schiff base monomer, ethyl methacrylate, and allyl glycidyl ether in a mass ratio of 1.6-2.1:16-20:3.5-4.5. The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0009] As a preferred embodiment of the present invention, the heating and stirring temperature in step two is 35-40℃, the stirring rate is 300-400r / min, the stirring time is 40-50min, and the grinding time is 1.5-2.0h.

[0010] As a preferred technical solution of the present invention, the preparation of the Schiff base monomer in the mixed monomer includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating and then microwave treatment, rotary evaporation, and freeze drying to obtain the product.

[0011] As a preferred embodiment of the present invention, the preheating temperature in the preparation of the Schiff base monomer is 40-45℃, the microwave treatment power is 400-500W and the treatment time is 10-15min, and the ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol is 1.5-2.0g: 1.0-1.3g: 0.10-0.12g: 30-40mL.

[0012] The beneficial effects of this invention are: The coating produced by this invention exhibits extremely strong adhesion in wood product applications, effectively adapting to the porous structure and high hydroxyl content of wood, thus achieving a tight bond with the wood surface. Through the synergistic effect of its various components, this coating achieves a significant antibacterial effect; its antibacterial properties are not only excellent but also long-lasting, effectively inhibiting the growth and reproduction of microorganisms for extended periods.

[0013] The coating prepared by this invention provides a reliable protective barrier for wood products, preventing them from being eroded by bacteria, mold, and other microorganisms. Simultaneously, it maintains a stable interfacial bonding state over a long period, ensuring that the appearance and performance of the wood products remain undamaged and extending their service life. This comprehensive performance makes the coating widely applicable and valuable in the field of wood products. Detailed Implementation

[0014] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0015] Example 1

[0016] A method for preparing an antibacterial coating for wood product surface treatment includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate to 50°C, add ethyl acetate, 2,6-di-tert-butyl-p-cresol and organotin catalyst T12 and mix, add polyether polyol and stir at 60°C for 4 hours, remove the solvent by rotary evaporation to obtain the prepolymer. In step one, the mass ratio of isocyanate, ethyl acetate, organotin catalyst T12, 2,6-di-tert-butyl-p-cresol, and polyether polyol is 60:35:0.02:0.015:20; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:1; and the polyether polyol DL-2000 has a functionality of 2. Step 2: Place the prepolymer, titanium white slurry, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a reaction vessel, heat and stir at 35℃ and 300r / min for 40min, grind for 1.5h, and filter to complete the preparation.

[0017] In step two, the mass ratio of the prepolymer, titanium white paste, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone is 52:16:1.8:120:4.2. The mixed monomers are composed of Schiff base monomers, ethyl methacrylate and allyl alcohol glycidyl ether in a mass ratio of 1.6:16:3.5.

[0018] The preparation of the Schiff base monomer in the mixed monomers includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating to 40°C, microwave treatment at 400W power for 10 min, removing the solvent by rotary evaporation, and freeze-drying to obtain the product.

[0019] The ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol is 1.5g:1.0g:0.10g:30mL.

[0020] Example 2

[0021] A method for preparing an antibacterial coating for wood product surface treatment includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate to 53°C, add ethyl acetate, 2,6-di-tert-butyl-p-cresol and organotin catalyst T12 and mix, add polyether polyol and stir at 63°C for 4.5 h, remove the solvent by rotary evaporation to obtain the prepolymer; In step one, the mass ratio of isocyanate, ethyl acetate, organotin catalyst T12, 2,6-di-tert-butyl-p-cresol, and polyether polyol is 63:37:0.023:0.016:21; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:1; and the polyether polyol DL-2000 has a functionality of 2. Step 2: Place the prepolymer, titanium white slurry, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a reaction vessel, heat and stir at 37℃ and 335r / min for 45min, grind for 1.6h, and filter to complete the preparation.

[0022] In step two, the mass ratio of the prepolymer, titanium white paste, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone is 56:18:1.9:125:4.5. The mixed monomers are composed of Schiff base monomers, ethyl methacrylate and allyl alcohol glycidyl ether in a mass ratio of 1.8:17:3.8.

[0023] The preparation of the Schiff base monomer in the mixed monomers includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating to 42°C, microwave treatment at 435W power for 12 min, removing the solvent by rotary evaporation, and freeze-drying to obtain the product.

[0024] The ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol is 1.7g:1.1g:0.107g:33mL.

[0025] Example 3

[0026] A method for preparing an antibacterial coating for wood product surface treatment includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate to 56°C, add ethyl acetate, 2,6-di-tert-butyl-p-cresol and organotin catalyst T12 and mix, add polyether polyol and stir at 66°C for 4.8 h, remove the solvent by rotary evaporation to obtain the prepolymer; In step one, the mass ratio of isocyanate, ethyl acetate, organotin catalyst T12, 2,6-di-tert-butyl-p-cresol, and polyether polyol is 67:40:0.027:0.017:23; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:1; and the polyether polyol DL-2000 has a functionality of 2. Step 2: Place the prepolymer, titanium white slurry, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a reaction vessel, heat and stir at 38℃ and 365r / min for 48min, grind for 1.8h, and filter to complete the preparation.

[0027] In step two, the mass ratio of the prepolymer, titanium white paste, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone is 60:19:2.0:130:4.7. The mixed monomers are composed of Schiff base monomers, ethyl methacrylate and allyl alcohol glycidyl ether in a mass ratio of 2.0:19:4.2.

[0028] The preparation of the Schiff base monomer in the mixed monomers includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating to 43°C, microwave treatment at 465W power for 13 min, removing the solvent by rotary evaporation, and freeze-drying to obtain the product.

[0029] The ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol is 1.8 g: 1.2 g: 0.113 g: 37 mL.

[0030] Example 4

[0031] A method for preparing an antibacterial coating for wood product surface treatment includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate to 60°C, add ethyl acetate, 2,6-di-tert-butyl-p-cresol and organotin catalyst T12 and mix, add polyether polyol and stir at 70°C for 5 hours, remove the solvent by rotary evaporation to obtain the prepolymer. In step one, the mass ratio of isocyanate, ethyl acetate, organotin catalyst T12, 2,6-di-tert-butyl-p-cresol, and polyether polyol is 70:42:0.03:0.018:24; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:1; and the polyether polyol DL-2000 has a functionality of 2. Step 2: Place the prepolymer, titanium white slurry, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a reaction vessel, heat and stir at 40℃ and 400r / min for 50min, grind for 2.0h, and filter to complete the preparation.

[0032] In step two, the mass ratio of the prepolymer, titanium white paste, nano silver, mixed monomers and 2-hydroxy-2-methyl-1-phenyl-1-propanone is 64:21:2.2:135:5.0. The mixed monomers are composed of Schiff base monomers, ethyl methacrylate and allyl alcohol glycidyl ether in a mass ratio of 2.1:20:4.5.

[0033] The preparation of the Schiff base monomer in the mixed monomers includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating to 45°C, microwave treatment at 500W power for 15 min, removing the solvent by rotary evaporation, and freeze-drying to obtain the product.

[0034] The ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol is 2.0 g: 1.3 g: 0.12 g: 40 mL.

[0035] Comparative Example 1

[0036] Compared with Example 2, Comparative Example 1 differs in that 2-hydroxy-4-vinylsalicylic aldehyde is used instead of the Schiff base monomer, while the other components and preparation process are the same.

[0037] Comparative Example 2

[0038] Compared with Example 2, Comparative Example 2 differs in that 2-aminobenzimidazole is used instead of the Schiff base monomer, while the other components and preparation process are the same.

[0039] Comparative Example 3

[0040] Compared with Example 2, Comparative Example 3 differs in that it does not use Schiff base monomers, while the other components and preparation processes are the same.

[0041] Comparative Example 4

[0042] Compared with Example 2, Comparative Example 4 differs in that ethyl methacrylate is used instead of allyl alcohol glycidyl ether, while the other components and preparation process are the same.

[0043] The coatings prepared in Examples 1-4 and Comparative Examples 1-4 were tested for the following properties: Adhesion test: in accordance with GB / T5210-2006; Antibacterial properties test: according to GB / T 21866-2008; The test results are shown in Table 1.

[0044] Table 1 Adhesion (MPa) Antibacterial rate (%) Example 1 5.8 99.2 Example 2 5.9 99.3 Example 3 6.0 99.5 Example 4 6.2 99.7 Comparative Example 1 4.9 82.1 Comparative Example 2 4.8 78.3 Comparative Example 3 4.7 71.8 Comparative Example 4 3.8 85.5 As can be seen from the test results in Table 1, compared with Comparative Examples 1-4, the coatings prepared by the present invention have excellent adhesion and antibacterial properties.

[0045] This invention utilizes the phenolic structure of 2-hydroxy-4-vinyl salicylic acid, which, due to its abundance of polar groups such as hydroxyl groups, can form hydrogen bonds with the hydroxyl groups on the surface of wood products, enhancing the interfacial adhesion between the coating and the wood. Simultaneously, the phenolic structure itself possesses certain antibacterial activity, capable of disrupting microbial cell membranes. Furthermore, its vinyl group can undergo copolymerization reactions with the ethyl methacrylate and allyl glycidyl ether unsaturated groups in the mixed monomers, increasing the crosslinking density of the coating system, reducing internal defects in the coating, and further optimizing coating adhesion. The amino group of 2-aminobenzimidazole can undergo a condensation reaction with the aldehyde group of 2-hydroxy-4-vinyl salicylic acid to form a Schiff base monomer. The imidazole structure contained in this monomer is the core antibacterial site, capable of inhibiting microbial metabolism and reproduction by binding to enzymes or nucleic acids within microorganisms. Moreover, the Schiff base monomer integrates the antibacterial structures of phenol and imidazole, producing a synergistic antibacterial effect, enhancing the broad spectrum and durability of antibacterial activity. Simultaneously, the polar groups such as the nitrogen atom in the Schiff base can also help improve the interfacial compatibility between the coating and the wood, indirectly contributing to improved adhesion. The epoxy groups of allyl alcohol glycidyl ether can undergo ring-opening reactions with hydroxyl groups on the wood surface and in the prepolymer to build a tighter interfacial bonding network, directly improving adhesion. On the other hand, it can form coordination or hydrogen bonds with hydroxyl groups on the surface of nano-silver, effectively preventing nano-silver agglomeration and ensuring uniform dispersion of nano-silver in the coating. This not only prevents weak points in the coating structure caused by agglomeration and ensures the adhesion of the coating to the wood, but also fully exposes the antibacterial active sites of nano-silver, further enhancing its antibacterial properties.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an antibacterial coating for surface treatment of wood products, characterized in that, The preparation method includes the following steps: Step 1: In a nitrogen atmosphere, preheat the isocyanate, add solvent, polymerization inhibitor and organotin catalyst and mix, add polyol and stir to react, remove the solvent by rotary evaporation to obtain the prepolymer; Step 2: Place the prepolymer, pigment, nano silver, mixed monomers and photoinitiator in a reaction vessel, heat and stir, grind, and filter to complete the preparation.

2. The method for preparing an antibacterial coating for surface treatment of wood products according to claim 1, characterized in that: The preheating temperature in step one is 50-60℃, and the stirring reaction temperature is 60-70℃ with a reaction time of 4-5 hours.

3. The method for preparing an antibacterial coating for surface treatment of wood products according to claim 1, characterized in that: In step one, the mass ratio of isocyanate, solvent, organotin catalyst, polymerization inhibitor and polyol is 60-70:35-42:0.02-0.03:0.015-0.018:20-24; the isocyanate is composed of MDI and IPDI in a mass ratio of 4:

1.

4. The method for preparing an antibacterial coating for surface treatment of wood products according to claim 1, characterized in that: In step two, the mass ratio of the prepolymer, pigment, nano-silver, mixed monomer, and photoinitiator is 52-64:16-21:1.8-2.2:120-135:4.2-5.

0. The mixed monomer is composed of Schiff base monomer, ethyl methacrylate, and allyl alcohol glycidyl ether in a mass ratio of 1.6-2.1:16-20:3.5-4.

5.

5. The method for preparing an antibacterial coating for surface treatment of wood products according to claim 1, characterized in that: In step two, the heating and stirring temperature is 35-40℃, the stirring rate is 300-400r / min, the stirring time is 40-50min, and the grinding time is 1.5-2.0h.

6. The method for preparing an antibacterial coating for surface treatment of wood products according to claim 1, characterized in that: The preparation of the Schiff base monomer in the mixed monomers includes mixing 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid and anhydrous ethanol, preheating and then microwave treating, rotary evaporating and freeze-drying to obtain the product.

7. The method for preparing an antibacterial coating for wood product surface treatment according to claim 6, characterized in that: In the preparation of the Schiff base monomer, the preheating temperature is 40-45℃, the microwave treatment power is 400-500W, the treatment time is 10-15min, and the ratio of 2-hydroxy-4-vinylsalicylic acid, 2-aminobenzimidazole, glacial acetic acid, and anhydrous ethanol is 1.5-2.0g: 1.0-1.3g: 0.10-0.12g: 30-40mL.

8. An antibacterial coating for surface treatment of wood products prepared by the preparation method according to any one of claims 1 to 7.