A sprayable paint tannin antibacterial waterproof coating and a preparation method thereof
The cross-linking of high-polyphenol polymers formed by high-temperature thermal polymerization with diisocyanates solves the problems of lacquer's easy aging and cracking outdoors and its poor alkali resistance, thus realizing the high performance and wide application of spray-applied urushiol antibacterial and waterproof coatings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-29
AI Technical Summary
Raw lacquer is prone to aging and cracking outdoors, has poor alkali resistance, is difficult to spray, and is allergenic, which limits its application in the industrial field.
High-temperature thermal polymerization is used to graft pyrogallol onto the side chain of urushiol to form a high-polyphenol polymer, which is then crosslinked with diisocyanate to generate a complex network structure, thereby improving the hardness and antibacterial properties of the paint film.
The resulting sprayable urushiol antibacterial and waterproof coating has excellent physical and mechanical properties, solvent resistance and chemical resistance, and also has a good antibacterial effect.
Abstract
Description
Technical Field
[0001] This invention relates to the field of biomass coating technology, and in particular to a sprayable urushiol antibacterial and waterproof coating and its preparation method. Background Technology
[0002] Raw lacquer is a natural coating, often hailed as the "King of Coatings." With a history of over 8,000 years, it is now widely used in furniture, handicrafts, decoration, construction, electronics, machinery, petroleum, textiles, printing and dyeing, and chemical industries. Urushiol is the main film-forming substance in raw lacquer, accounting for approximately 50-80% of its content. Its chemical structure is primarily a derivative of catechol, with the benzene ring side chains mainly composed of C15-C17 unsaturated straight-chain alkanes. After curing, natural raw lacquer exhibits excellent corrosion resistance, abrasion resistance, and acid and alkali resistance, remaining intact for thousands of years. However, the film-forming conditions for raw lacquer are quite demanding, requiring specific temperature and humidity levels for drying. The lacquer film also has poor UV absorption resistance, making it prone to aging and cracking outdoors. Furthermore, it suffers from poor alkali resistance, difficulty in spraying, and sensitizing properties, thus hindering its industrial development.
[0003] To expand the application areas of raw lacquer, many researchers have conducted extensive research and achieved groundbreaking progress in the modification of raw lacquer. Hu Binghuan and Lin Jinhuo, among others, utilized the phenolic hydroxyl groups in urushiol to chelate with metals to form urushiol-metal polymer coatings. These polymers can dry to form a film at room temperature without the catalysis of laccase, significantly shortening the drying time compared to raw lacquer. Furthermore, the coating film exhibits good thermal stability and excellent anti-corrosion properties. Urushiol formaldehyde resin can also be synthesized through condensation polymerization, possessing superior properties compared to raw lacquer; however, it uses formaldehyde, which is not environmentally friendly. Another approach involves reacting phenolic hydroxyl groups with epichlorohydrin to generate polyepoxyl urushiol epoxy resin. Because the phenolic hydroxyl groups react with epichlorohydrin to form ethers, they do not further oxidize to quinones during curing. Therefore, the coating film is light in color and has good flexibility and alkali resistance, but due to its other poor properties, its value as a standalone product is not high.
[0004] This invention utilizes the high-temperature thermal polymerization reaction between urushiol and pyrogallic acid to graft pyrogallic acid onto the side chains of the urushiol compound, followed by further polymerization to form a high-polyphenol polymer with excellent antibacterial properties. Then, the high-polyphenol polymer is reacted with diisocyanate; the hydroxyl groups react with the isocyanate, and the double bonds of the urushiol side chains crosslink, generating a complex network structure. This improves the hardness and corrosion resistance of the paint film while also providing excellent antibacterial effects. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, broaden the application of urushiol, and provide a sprayable urushiol antibacterial and waterproof coating and its preparation method.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A sprayable urushiol antibacterial and waterproof coating and its preparation method are characterized by comprising the following steps: first step Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:10 to 1:30 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 30 to 50 °C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallol was added at a mass ratio of 1:1 to 5:3. The mixture was heated and stirred without solvent at a temperature of 160 to 190 °C for 5 to 30 h to obtain a high-polyphenol polymer, which was then sealed in an inert environment for later use. Step 2 The high polyphenol polymer, turpentine oil, mellow tung oil, ultrafine spherical SiO2, silane coupling agent and leveling agent are stirred at 50-100℃ for 1-3 hours in a mass ratio of (10-20):(20-40):(10-20):(20-40):(1-5):(1-5) to obtain component A; Step 3 The high polyphenol polymer and isocyanate were reacted at 90°C for 1-3 hours at a mass ratio of 5-10:1 to obtain a prepolymer; the prepolymer, diisocyanate and turpentine were mixed evenly at a mass ratio of 1:1:5 to form component B. Step 4 When using, mix component A and component B in a volume ratio of 1:1 using a spraying machine until homogeneous before spraying.
[0007] The urushiol mixture is a mixture of triene urushiol, diene urushiol, monoene urushiol, saturated urushiol, and urushiol dimer.
[0008] The polyphenol polymer has a polyphenol content of ≥80%.
[0009] The high-polyphenol polymer is obtained by high-temperature thermal polymerization of urushiol and pyrogallol.
[0010] The polyphenol polymer exhibits excellent antibacterial properties, with a minimum inhibitory concentration (MIC) of 0.5 mg / mL against Staphylococcus aureus, 31.25 μg / mL against Staphylococcus epidermidis, 3.75 mg / mL against Candida albicans, and 15 mg / mL against Escherichia coli.
[0011] The silane coupling agent is one of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane.
[0012] The isocyanate is one or more of ethyl isocyanate, propyl isocyanate, and lauryl isocyanate.
[0013] The diisocyanate is one or more of 1,6-hexanediisocyanate, isophorone diisocyanate, trimethyl-1,6-hexanediisocyanate, hexamethylene diisocyanate, and transcyclohexane diisocyanate.
[0014] The aforementioned antibacterial and waterproof coating can be used in fields such as medical devices, food equipment, furniture decoration, and building coatings.
[0015] The beneficial effects of this invention are: The sprayable urushiol antibacterial and waterproof coating and its preparation method provided by the present invention also have the following characteristics: This invention utilizes a high-temperature reaction at 160~190℃ in the absence of solvents to graft pyrogallol onto the side chain of urushiol, forming a polyphenol-type urushiol polymer with high polyphenol content and good antibacterial activity.
[0016] The reaction of polyphenolic hydroxyl urushiol compounds with dicyanate provides multiple hydroxyl reaction sites, forming a complex three-dimensional network structure with multiple penetrations, which gives the coating excellent physical and mechanical properties, solvent resistance and chemical resistance. Detailed Implementation
[0017] The raw lacquer used in the following examples was collected from the lacquer tree (Latin name: *Toxicodendron vernicifluum*, originating from Hubei Province). The urushiol used was a mixture of triene urushiol, diene urushiol, monoene urushiol, saturated urushiol, and urushiol dimers.
[0018] Example 1: Preparation of high-polyphenol polymers Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:10 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 30°C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallic acid was added at a mass ratio of 1:1 to the urushiol mixture. The mixture was heated and stirred in a solvent-free environment at 160°C for 30 h to obtain a high-polyphenol polymer, which was then sealed and stored in an inert environment for later use.
[0019] Example 2 Preparation of high-polyphenol polymers Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:20 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 40°C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallic acid was added at a mass ratio of 4:3 to the urushiol mixture. The mixture was heated and stirred in a solvent-free environment at 170°C for 25 h to obtain a high-polyphenol polymer, which was then sealed and stored in an inert environment for later use.
[0020] Example 3 Preparation of high-polyphenol polymers Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:30 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 50°C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallic acid was added at a mass ratio of 5:3 to the urushiol mixture. The mixture was heated and stirred in a solvent-free environment at 180°C for 15 h to obtain a high-polyphenol polymer, which was then sealed and stored in an inert environment for later use.
[0021] Example 4 Preparation of high-polyphenol polymers Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:30 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 50°C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallic acid was added at a mass ratio of 1:1 to the urushiol mixture. The mixture was heated and stirred in a solvent-free environment at 190°C for 5 hours to obtain a high-polyphenol polymer, which was then sealed and stored in an inert environment for later use.
[0022] Example 5 Preparation of high-polyphenol polymers Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:20 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 40°C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallic acid was added at a mass ratio of 4:3 to the urushiol mixture. The mixture was heated and stirred in a solvent-free environment at 190°C for 10 h to obtain a high-polyphenol polymer, which was then sealed and stored in an inert environment for later use.
[0023] The polyphenol content of the high-polyphenol polymers prepared in Examples 1-5 above was determined, and the specific results are shown in Table 1.
[0024] Table 1. High-polyphenol polymers prepared in Examples 1-5 Polyphenol content (%) Example 1 81.58 Example 2 80.37 Example 3 81.68 Example 4 80.43 Example 5 81.15 Example 6 Antibacterial effect Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Candida albicans were inoculated into lysozyme (LB) liquid medium in a clean bench and cultured at 37°C and 120 r / min for 24 h. A small amount of bacterial solution was taken, diluted with LB liquid medium, and the bacterial concentration was measured using a turbidimeter. The bacterial concentration was controlled at 10⁸ CFU / mL, and then diluted 100 times for later use.
[0025] Add 1% dimethyl sulfoxide and 5% Tween 80 to the high-polyphenol polymer, then dissolve in water and serially dilute to concentrations of 30, 15, 7.5, 3.75, 2, 1 mg / mL, 0.5 mg / mL, 0.25 mg / mL, 0.125 mg / mL, 62.5 μg / mL, 31.25 μg / mL, 15.625 μg / mL, and 7.813 μg / mL. Take a 12×100 mm glass test tube, add 1 mL of the high-polyphenol polymer solution of different concentrations to the test tube, and then add 1 mL of bacterial suspension (the final bacterial concentration of each test tube is 5×10⁻⁶). 5 CFU / mL). 1 mL of 1% dimethyl sulfoxide aqueous solution and 1 mL of bacterial suspension were used as blank controls. Gentamicin sulfate was used as a positive control. The test tubes were placed in a 37°C incubator for 24 h, and then each test tube was observed. If the solution was clear, it indicated that the sample inhibited growth. The lowest concentration corresponding to the clear test tube was the minimum inhibitory concentration (MIC) of the sample against the bacteria.
[0026] The results of Examples 1-5 are shown in Table 2.
[0027] The high-polyphenol polymer has excellent antibacterial properties, with a minimum inhibitory concentration (MIC) of 0.5 mg / mL against Staphylococcus aureus, 31.25 μg / mL against Staphylococcus epidermidis, 3.75 mg / mL against Candida albicans, and 15 mg / mL against Escherichia coli.
[0028] Table 2. Minimum inhibitory concentrations against Staphylococcus aureus, Staphylococcus epidermidis, Candida albicans, and Escherichia coli. Staphylococcus aureus Staphylococcus epidermidis Candida albicans E. coli MIC (mg / mL) MIC (μg / mL) MIC (mg / mL) MIC (mg / mL) Example 1 0.5 32.25 3.75 15 Example 2 0.5 31.25 3.75 15 Example 3 0.5 31.25 3.75 15 Example 4 0.5 31.25 3.75 15 Example 5 0.5 31.25 3.75 15 Example
[0029] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltriethoxysilane, and leveling agent at 50°C for 3 hours in a mass ratio of 20:40:10:20:2:5. Component B is obtained by reacting the high-polyphenol polymer and ethyl isocyanate at 90°C for 1 hour in a mass ratio of 5:1. Component B is obtained by mixing the prepolymer, 1,6-hexanediisocyanate, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0030] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltrimethoxysilane, and leveling agent at 60°C for 3 hours in a mass ratio of 10:40:20:40:1:4. Component B is obtained by reacting the high-polyphenol polymer and propyl isocyanate at 90°C for 2 hours in a mass ratio of 6:1. Component B is obtained by mixing the prepolymer, isophorone diisocyanate, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0031] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltris(β-methoxyethoxy)silane, and leveling agent at 70°C for 2 hours in a mass ratio of 15:30:15:30:3:3. Component B is obtained by reacting the high-polyphenol polymer and lauryl isocyanate at 90°C for 2 hours in a mass ratio of 7:1. Component B is obtained by mixing the prepolymer, trimethyl-1,6-hexanediol diisocyanate, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0032] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltris(β-methoxyethoxy)silane, and leveling agent at 80°C for 2 hours in a mass ratio of 15:40:10:20:4:2. Component B is obtained by reacting the high-polyphenol polymer with (propyl isocyanate: lauryl isocyanate = 1:1) at 90°C for 3 hours in a mass ratio of 8:1. Component B is obtained by mixing the prepolymer, hexamethylene diisocyanate, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0033] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltriethoxysilane, and leveling agent at 90°C for 1 hour in a mass ratio of 20:20:15:30:5:1. Component B is obtained by reacting the high-polyphenol polymer with (propyl isocyanate:ethyl isocyanate = 1:1) at 90°C for 3 hours in a mass ratio of 9:1. Component B is obtained by mixing the prepolymer, trans-cyclohexane diisocyanate, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0034] Component A is obtained by stirring high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltrimethoxysilane, and leveling agent at 80°C for 2 hours in a mass ratio of 20:30:10:40:3:3. Prepolymer is obtained by reacting high-polyphenol polymer with (ethyl isocyanate: lauryl isocyanate = 1:1) at a mass ratio of 10:1 at 90°C for 2 hours. Component B is obtained by mixing the prepolymer, 1,6-hexanediisocyanate: isophorone diisocyanate = 1:1, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0035] Component A is obtained by stirring a high-polyphenol polymer, turpentine oil, mellowed tung oil, ultrafine spherical SiO2, vinyltrimethoxysilane, and leveling agent at 80°C for 2 hours in a mass ratio of 20:30:10:40:3:3. A prepolymer is obtained by reacting the high-polyphenol polymer with (ethyl isocyanate: lauryl isocyanate = 1:1) at a mass ratio of 10:1 at 90°C for 2 hours. Component B is obtained by mixing the prepolymer, trimethyl-1,6-hexanediisocyanate: hexamethylene diisocyanate: trans-cyclohexane diisocyanate = 1:1:1, and turpentine oil in a mass ratio of 1:1:5. For application, components A and B in a volume ratio of 1:1 are mixed evenly using a sprayer and then sprayed. Example
[0036] The performance of the sprayable urushiol antibacterial and waterproof coatings prepared according to Examples 7-13 above all meet the test results in Table 3.
[0037] Table 3 Performance Test Results Testing items Test Results Surface drying time, h 0.5 Practical time, h 12 hardness 3H Flexibility, φ, mm 1 Impact strength, kg.cm 50 Adhesion, grade 1 Acid resistance No change in 114 hours Alkali resistance No change in 114 hours Solvent resistant No change in 114 hours Antibacterial rate against Staphylococcus aureus / % ≥98% Antibacterial rate against Escherichia coli / % ≥98% The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A sprayable urushiol antibacterial and waterproof coating and its preparation method, characterized in that, Includes the following steps: first step Raw lacquer was placed in a beaker, and anhydrous ethanol was added at a mass-to-volume ratio of 1:10 to 1:30 g / mL. After stirring evenly, the mixture was centrifuged, and the supernatant was evaporated under reduced pressure at 30 to 50 °C to remove the ethanol, yielding a urushiol mixture. The urushiol mixture was then placed in a flask, and pyrogallol was added at a mass ratio of 1:1 to 5:
3. The mixture was heated and stirred without solvent at a temperature of 160 to 190 °C for 5 to 30 h to obtain a high-polyphenol polymer, which was then sealed in an inert environment for later use. Step 2 The high polyphenol polymer, turpentine oil, mellow tung oil, ultrafine spherical SiO2, silane coupling agent and leveling agent are stirred at 50-100℃ for 1-3 hours in a mass ratio of (10-20):(20-40):(10-20):(20-40):(1-5):(1-5) to obtain component A; Step 3 The high polyphenol polymer and isocyanate were reacted at 90°C for 1-3 hours at a mass ratio of 5-10:1 to obtain a prepolymer; the prepolymer, diisocyanate and turpentine were mixed evenly at a mass ratio of 1:1:5 to form component B. Step 4 When using, mix component A and component B in a volume ratio of 1:1 using a spraying machine until homogeneous before spraying.
2. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... The urushiol mixture in the first step is a mixture of triene urushiol, diene urushiol, monoene urushiol, saturated urushiol, and urushiol dimer.
3. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... The high polyphenol polymer obtained in the first step has a polyphenol content of ≥80%.
4. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... The high-polyphenol polymer in the first step is obtained by high-temperature thermal polymerization of urushiol and pyrogallol.
5. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... The polyphenol polymer in the first step has excellent antibacterial properties, with a minimum inhibitory concentration (MIC) of 0.5 mg / mL against Staphylococcus aureus, 31.25 μg / mL against Staphylococcus epidermidis, 3.75 mg / mL against Candida albicans, and 15 mg / mL against Escherichia coli.
6. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... The silane coupling agent in the second step is one of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane.
7. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... In the third step, the isocyanate is one or more of ethyl isocyanate, propyl isocyanate, and lauryl isocyanate.
8. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... In the third step, the diisocyanate is one or more of the following: 1,6-hexanediisocyanate, isophorone diisocyanate, trimethyl-1,6-hexanediisocyanate, hexamethylene diisocyanate, and transcyclohexane diisocyanate.
9. The sprayable urushiol antibacterial and waterproof coating and its preparation method according to claim 1, characterized in that... Antibacterial and waterproof coatings can be used in fields such as medical devices, food equipment, furniture decoration, and building coatings.