Self-crosslinking wood lacquer emulsion and preparation method thereof

Abstract

The invention discloses a self-crosslinking wood lacquer emulsion and a preparation method thereof, and relates to the technical field of high polymer material synthesis. Wherein the weight-average molecular weight of the alkali-soluble solid resin is 2000 to 14000, and the acid value of the alkali-soluble solid resin is 40 to 260; the content of the alkali-soluble solid resin is 10-80% based on the total dry weight of the emulsion, and the theoretical acid value of the emulsion is 10-70; the emulsion polymer is synthesized by a mixture comprising at least one hydrophobic monoethylenically unsaturated monomer and at least one hydrophilic monoethylenically unsaturated monomer; the polyurethane is used as a main body, the acrylic acid material is used for modifying the polyurethane, the advantages of the waterborne polyurethane and the acrylic acid material are integrated, so that the waterborne polyurethane can fully meet the comprehensive material characteristic requirements of the leather base coat, and the prepared waterborne polyurethane not only has the properties of high filling and covering properties, good knurling and shaping properties and good recoatability of the leather base coat resin, but also has the advantages of low cost, low cost and the like. And the flexible cable has excellent flexure resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material synthesis, and particularly relates to a self-crosslinking wood paint emulsion and a preparation method thereof. Background Art

[0003] At present, water-based wood paint coatings on the market mainly use water-based acrylic emulsion as the main film-forming substance, and water-based acrylic emulsion accounts for more than 80% of water-based wood paint coatings, so the quality of water-based acrylic emulsion is directly related to the use effect of water-based wood paint coatings. Water-based wood paint emulsions mainly include one-component and two-component water-based acrylic emulsions. Although the two-component water-based acrylic emulsion is better than the one-component water-based acrylic emulsion in performance, when the two-component water-based acrylic emulsion is used in water-based wood paint coatings, the coating construction is complicated, the cost is high, and it contains a certain amount of solvent. These factors lead to the application of water-based two-component emulsions in wood coatings. The application is greatly restricted, so the current film-forming substance of water-based wood paint coatings is mainly one-component water-based acrylic emulsion, but the one-component water-based acrylic emulsion has low hardness, low gloss, poor resistance and adhesion. These factors greatly affect the wide application of one-component water-based acrylic emulsion in water-based wood paint coatings. Summary of the invention

[0004] The purpose of the present invention is to solve the above technical problems and provide a self-crosslinking wood paint emulsion and a preparation method thereof, which at least partially solve the above problems.

[0005] The technical solution adopted by the present invention is: a self-crosslinking wood paint emulsion, including alkali-soluble solid resin and emulsion polymer; Wherein, the weight average molecular weight of the alkali-soluble solid resin is 2000-14000, and the acid value is 40-260; The alkali-soluble solid resin has a content of 10-80% based on the total dry weight of the emulsion, and the theoretical acid value of the emulsion is 10-70; The emulsion polymer is synthesized from a mixture including at least one hydrophobic monoethylenically unsaturated monomer and at least one hydrophilic monoethylenically unsaturated monomer.

[0006] Furthermore, the alkali-soluble acrylic resin is any one of acrylic resin S-120, acrylic resin S-60, acrylic resin S-80, and acrylic resin S-678.

[0007] Furthermore, the alkali-soluble acrylic resin is made water-soluble by a neutralizing agent; The neutralizing agent is any one or a mixture of sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium acetate, sodium pyrophosphate, sodium carbonate, ammonia water, hydrochloric acid, phosphoric acid, formic acid, acetic acid, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, and glycine.

[0008] Furthermore, the hydrophobic monoethylenically unsaturated monomer is any one or a mixture of (meth)acrylate monomers, (meth)acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monoethylenically unsaturated di- and tricarboxylate monomers.

[0009] Furthermore, the (meth)acrylate monomer is any one or a mixture of C1-C19-alkyl (meth)acrylates; The styrene monomer is any one or a mixture of unsubstituted styrene or C1-C6-alkyl-substituted styrene; The vinyl alkanoate monomer is any one or a mixture of vinyl esters of C2-C11 alkanoic acids; The monoethylenically unsaturated dicarboxylic and tricarboxylic acid ester monomers are any one or a mixture of the full esters of monoethylenically unsaturated dicarboxylic acids and tricarboxylic acids.

[0010] Furthermore, the hydrophobic monoethylenically unsaturated monomer accounts for 85% or more based on the total weight of the emulsion polymer.

[0011] Furthermore, the hydrophilic monoethylenically unsaturated monomer is a monoethylenically unsaturated monomer containing at least one functional group selected from carboxyl, carboxylic anhydride, sulfonic acid, phosphoric acid, hydroxyl, and amide.

[0012] Furthermore, the mixture may further contain one or more crosslinking monomers; The emulsion further includes an initiator, an emulsifier, and a fungicide; Wherein the initiator is one of a peroxide thermal initiator, a persulfate thermal initiator, and an azo compound thermal initiator; The emulsifier is a reactive surfactant, and the emulsifier contains at least one ethylenically unsaturated functional group.

[0013] On the other hand, the present invention also provides a method for preparing a self-crosslinking wood lacquer emulsion, comprising the following steps: Put deionized water and an alkali-soluble solid resin into a reaction kettle; Add an ammonia water solution to the reaction kettle under stirring within 5-10 minutes, heat the reaction kettle to 70-90 °C and stir for 1.5-3 hours; After cooling to room temperature, filter to obtain an alkali-soluble resin solution; Put deionized water, alkali-soluble resin solution, and emulsifier into a reaction kettle, stir while heating to 80 - 90 °C; After adding the initiator, slowly add the mixture to the reaction kettle within 2 - 3 h, and simultaneously dropwise add the initiator; Cool the reaction kettle to 30 - 50 °C, and sequentially add crosslinking monomer and bactericide to obtain a self-crosslinking wood lacquer emulsion.

[0014] On the other hand, the present invention also provides an application of a self-crosslinking wood lacquer emulsion, using the self-crosslinking wood lacquer emulsion as a raw material to prepare an acrylic emulsion wood lacquer.

[0015] The beneficial effects of the present invention are: The present invention takes polyurethane as the main body and modifies it with acrylic materials, combining the advantages of waterborne polyurethane and acrylic, enabling it to fully meet the comprehensive material property requirements of leather base coating. The prepared waterborne polyurethane not only has strong filling and covering properties, good embossing and shaping properties, and good recoating properties of leather base coating resin, but also has excellent flexural resistance. Detailed implementation manners

[0016] In order that those skilled in the art can better understand the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0017] Unless otherwise specified, all terms / proprietary nouns / nomenclatures used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains.

[0018] When the expressions "a", "an", and "the" are used to define a term, they include the plural and singular forms of the term.

[0019] As used herein, the term "polymer" or "polymers" includes homopolymers, i.e., polymers prepared from a single reactive compound; and copolymers, i.e., polymers prepared by the reaction of at least two reactive monomer compounds that form polymers.

[0020] The name (meth)acrylate and similar names are used herein as abbreviated representations of "acrylate and / or methacrylate".

[0021] Unless otherwise specified, all percentages and ratios represent weight percentages and weight ratios.

[0022] The term weight-average molecular weight (Mw) refers to the molecular weight measured by gel permeation chromatography (GPC) in tetrahydrofuran relative to a polystyrene standard, with the unit of g / mol.

[0023] The term acid value (AV) refers to the acid value of each g of resin expressed in mg KOH (base), which is determined by titrating the bulk resin dissolved in tetrahydrofuran (THF) with 0.1 N KOH aqueous solution. And the term theoretical acid value (TAV) refers to the theoretical acid value calculated according to the following equation: TAV = AV of alkali-soluble solid resin * (weight percentage of alkali-soluble solid resin relative to the total weight of the emulsion) + AV of emulsion polymer * (weight percentage of emulsion polymer relative to the total weight of the emulsion).

[0024] Therefore, the present invention provides a self-crosslinking wood paint emulsion, comprising an alkali-soluble solid resin and an emulsion polymer; wherein, the weight-average molecular weight of the alkali-soluble solid resin is 2000 - 14000, and the acid value is 40 - 260; the content of the alkali-soluble solid resin based on the total dry weight of the emulsion is 10 - 80%, and the theoretical acid value of the emulsion is 10 - 70; the emulsion polymer is synthesized by a mixture, and the mixture includes at least one hydrophobic monoethylenically unsaturated monomer and at least one hydrophilic monoethylenically unsaturated monomer.

[0025] The weight-average molecular weight of the alkali-soluble solid resin in the self-crosslinking wood paint has a significant impact on its performance. The molecular weight affects the drying speed of the paint film. Lower molecular weight resins result in a faster drying speed because small molecules are more likely to migrate and participate in the crosslinking reaction. However, if the molecular weight is too low, it may reduce the final hardness and durability of the paint film. On the contrary, high molecular weight resins may take longer to complete the crosslinking process, thus slowing down the drying speed, but can provide better mechanical properties. Therefore, using the alkali-soluble solid resin with the above weight-average molecular weight can have good mechanical properties while ensuring a certain reaction speed.

[0026] In a further embodiment of this example, the alkali-soluble acrylic resin is any one of acrylic resin S-120, acrylic resin S-60, acrylic resin S-80, and acrylic resin S-678.

[0027] In a further embodiment of this example, the alkali-soluble acrylic resin is made water-soluble through a neutralizing agent; the neutralizing agent is any one or a mixture of sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium acetate, sodium pyrophosphate, sodium carbonate, ammonia water, hydrochloric acid, phosphoric acid, formic acid, acetic acid, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, and glycine.

[0028] In a further embodiment of the present embodiment, the hydrophobic monoethylenically unsaturated monomer is any one or a mixture of (meth)acrylate monomers, (meth)acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monoethylenically unsaturated di- and tricarboxylate monomers.

[0029] In a further embodiment of the present embodiment, the (meth)acrylate monomer is any one or a mixture of C1-C19-alkyl (meth)acrylates; The styrene monomer is any one or a mixture of unsubstituted styrene or C1-C6-alkyl-substituted styrene; The vinyl alkanoate monomer is any one or a mixture of vinyl esters of C2-C11 alkanoic acids; The monoethylenically unsaturated dicarboxylic and tricarboxylate monomers are any one or a mixture of full esters of monoethylenically unsaturated dicarboxylic acids and tricarboxylic acids.

[0030] In a further embodiment of the present embodiment, the hydrophobic monoethylenically unsaturated monomer accounts for 85% or more based on the total weight of the emulsion polymer.

[0031] In a further embodiment of the present embodiment, the hydrophilic monoethylenically unsaturated monomer is a monoethylenically unsaturated monomer containing at least one functional group selected from carboxyl, carboxylic anhydride, sulfonic acid, phosphoric acid, hydroxyl, and amide.

[0032] In a further embodiment of the present embodiment, the mixture may further comprise one or more crosslinking monomers; The emulsion further includes an initiator, an emulsifier, and a fungicide; Wherein the initiator is one of a peroxide thermal initiator, a persulfate thermal initiator, and an azo compound thermal initiator; The emulsifier is a reactive surfactant, and the emulsifier contains at least one ethylenically unsaturated functional group.

[0033] On the other hand, the present invention also provides a method for preparing a self-crosslinking wood lacquer emulsion, comprising the following steps: Put deionized water and an alkali-soluble solid resin into a reaction kettle; Add an ammonia water solution to the reaction kettle within 5-10 minutes under stirring, heat the reaction kettle to 70-90 °C and stir for 1.5-3 hours; Filter after cooling to room temperature to obtain an alkali-soluble resin solution; Put deionized water, the alkali-soluble resin solution, and an emulsifier into a reaction kettle, stir and heat to 80-90 °C; After adding the initiator, slowly add the mixture to the reaction kettle within 2 - 3 h, and simultaneously add the initiator dropwise. Cool the reaction kettle to 30 - 50 °C, and sequentially add the crosslinking monomer and the bactericide to obtain the self - crosslinking wood lacquer emulsion.

[0034] On the other hand, the present invention also provides an application of the self - crosslinking wood lacquer emulsion, using the self - crosslinking wood lacquer emulsion as a raw material to prepare an acrylic emulsion wood lacquer.

[0035] It should be noted that: The emulsion polymer of the present invention can be synthesized using a mixture, and the mixture contains at least one hydrophobic monounsaturated monomer and at least one hydrophilic monounsaturated monomer.

[0036] The at least one hydrophobic monounsaturated monomer can be selected from (meth)acrylate monomers, (meth)acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monounsaturated di - and tricarboxylate monomers.

[0037] In particular, the (meth)acrylate monomer can be a C1 - C19 - alkyl (meth)acrylate, such as but not limited to methyl (meth)acrylate, ethyl (meth)acrylate, n - butyl (meth)acrylate, 2 - ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, n - octyl (meth)acrylate, n - decyl (meth)acrylate, n - dodecyl (meth)acrylate (i.e., lauryl (meth)acrylate), tetradecyl (meth)acrylate, octadecenyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, and their mixtures.

[0038] In particular, the styrene monomer can be unsubstituted styrene or C1 - C6 - alkyl - substituted styrene, such as but not limited to styrene; α - methylstyrene; o -, m -, and p - methylstyrene; o -, m -, and p - ethylstyrene; o,p - dimethylstyrene; o,p - diethylstyrene; isopropylstyrene; o - methyl - p - isopropylstyrene, or any mixture thereof.

[0039] In particular, the vinyl alkanoate monomer can be a vinyl ester of a C2 - C11 alkanoic acid, such as but not limited to vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl caproate, vinyl versatate, or their mixtures.

[0040] In addition, the monounsaturated dicarboxylic and tricarboxylic acid ester monomers can be full esters of monounsaturated dicarboxylic and tricarboxylic acids, such as but not limited to diethyl maleate, dimethyl fumarate, ethyl methyl itaconate, or any mixture thereof.

[0041] In a preferred embodiment of the present invention, one or more C1 -C12 alkyl (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, styrene, or a mixture thereof are selected as at least one hydrophobic monounsaturated monomer.

[0042] Based on the total weight of the emulsion polymer, the hydrophobic monomer may account for at least 85% by weight, preferably at least 90% by weight, more preferably at least 95% by weight.

[0043] The at least one hydrophilic monounsaturated monomer may be a monounsaturated monomer containing at least one functional group selected from carboxyl, carboxylic anhydride, sulfonic acid, phosphoric acid, hydroxyl, and amide.

[0044] In particular, the hydrophilic monounsaturated monomer (b) includes but is not limited to monounsaturated carboxylic acids, such as (meth)acrylic acid, itaconic acid, fumaric acid, citraconic acid, sorbic acid, cinnamic acid, glutaric acid, and maleic acid; monounsaturated carboxylic anhydrides, such as itaconic anhydride, fumaric anhydride, citraconic anhydride, sorbic anhydride, cinnamic anhydride, glutaric anhydride, and maleic anhydride; monounsaturated amides, especially N-alkanolamides, such as (meth)acrylamide, N-hydroxymethyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylamide; and hydroxyalkyl esters of monounsaturated carboxylic acids, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

[0045] In a preferred embodiment of the present invention, acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, or a mixture thereof is preferably used as at least one hydrophilic monounsaturated monomer.

[0046] The monomers for the emulsion polymer of the present invention may also contain one or more crosslinking monomers. The crosslinking monomer in the present invention is diacetone acrylamide. After being blended with adipic dihydrazide in the emulsion, as the water in the emulsion volatilizes, the pH value of the system becomes weakly acidic, and a condensation reaction occurs between the ketone carbonyl group and the amino group to form a hydrazone structure, causing the ketone hydrazide to undergo a crosslinking reaction, thereby obtaining a polymer with a high-strength crosslinked network structure, making the film-forming emulsion have high water resistance, high hardness, and high gloss.

[0047] The initiator used in the present invention is a thermal initiator, such as peroxides, persulfates, and azo compounds. The peroxides that can be used include, but are not limited to, inorganic peroxides, such as hydrogen peroxide or persulfates, or organic peroxides, such as tert-butyl hydroperoxide, tert-butyl peroxyneopentanoate, and dialkyl or diaryl peroxides, such as di-tert-butyl or dicumyl peroxide. The azo compounds that can be used include, but are not limited to, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile). Among them, sodium persulfate (SPS), potassium persulfate (KPS), and ammonium persulfate (APS) are preferably used as thermal initiators; the dosage of the initiator is generally not more than 10% by weight, preferably 0.02% to 5% by weight, more preferably 0.1% to 1.5% by weight, based on the total weight of the emulsion polymer.

[0048] The emulsifier used in the present invention is a reactive surfactant, which contains at least one ethylenically unsaturated functional group. Suitable polymerizable surfactants include, for example, but are not limited to allyl polyoxyalkylene ether sulfates, such as sodium allyl polyoxyethylene alkyl ether sulfate, sodium allyl alkyl succinate sulfonate; allyl ether hydroxypropyl sulfonate; polyoxyethylene styrenated phenyl ether sulfate; polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene propoxy nonylphenoxy propyl ether; and phosphate ester acrylate. Among them, SR-10 is preferably used as the reactive emulsifier of the present invention; the total amount is 0.1% to 6% by weight, based on the total weight of the monomers.

[0049] Example 1 309.7 g of deionized water and 150 g of S-678 were charged into a 2 L reactor. At room temperature, 40.4 g of an ammonia water solution (25% aqueous solution) was added to the reaction kettle with stirring within 5 minutes. The reaction kettle was heated to 80 °C and stirred at 80 °C for 120 min. Then the solution was cooled to room temperature and the product was filtered. The pH of the final alkali-soluble resin solution was about 8.1 and the solid content was about 30% by weight.

[0050] 184.8 g of deionized water, 145.7 g of alkali-soluble resin solution, and 3.9 g of SR-10 were charged into a 1 L reactor and heated to 85 °C with stirring. Ammonium persulfate (0.8 g) was added together with water (3.1 g). Butyl acrylate, methyl methacrylate, diacetone acrylamide, and adipic dihydrazide (total weight of 174.7 g) were slowly added to the reactor within 120 minutes, and at the same time, a mixture of ammonium persulfate (1.1 g) and water (20 g) was added dropwise. After the addition was completed, it was kept warm for 60 minutes. Then it was cooled to 40 °C, 2 g of adipic dihydrazide was added, and a bactericide (1.5 g) was added.

[0051] The solid content of the final emulsion is 41%, the particle size is 65 nm, and the pH is 8.01.

[0052] Example 2 309.7 g of deionized water and 150 g of S-678 were charged into a 2 L reactor. At room temperature, 40.4 g of an aqueous ammonia solution (25% aqueous solution) was added to the reaction kettle with stirring within 5 minutes. The reaction kettle was heated to 80 °C and stirred at 80 °C for 120 min. Then the solution was cooled to room temperature and the product was filtered. The pH of the final alkali-soluble resin solution was about 8.1 and the solid content was about 30% by weight.

[0053] 184.8 g of deionized water, 145.7 g of alkali-soluble resin solution, and 3.9 g of SR-10 were charged into a 1 L reactor and heated to 85 °C with stirring. Ammonium persulfate (0.8 g) was added together with water (3.1 g). Butyl acrylate, methyl methacrylate, ethylene glycol bis(acetoacetate) methacrylate, and adipic dihydrazide (total weight 174.7 g) were slowly added to the reactor within 120 minutes, while dropping a mixture of ammonium persulfate (1.1 g) and water (20 g). After the dropping was completed, it was kept warm for 60 minutes. Then it was cooled to 40 °C, 2 g of adipic dihydrazide was added, and a fungicide (1.5 g) was added.

[0054] The solid content of the final emulsion is 41%, the particle size is 65 nm, and the pH is 8.01.

[0055] Example 3 309.7 g of deionized water and 150 g of S-678 were charged into a 2 L reactor. At room temperature, 40.4 g of an aqueous ammonia solution (25% aqueous solution) was added to the reaction kettle with stirring within 5 minutes. The reaction kettle was heated to 80 °C and stirred at 80 °C for 120 min. Then the solution was cooled to room temperature and the product was filtered. The pH of the final alkali-soluble resin solution was about 8.1 and the solid content was about 30% by weight.

[0056] 184.8 g of deionized water, 145.7 g of alkali-soluble resin solution, and 3.9 g of SR-10 were charged into a 1 L reactor and heated to 85 °C with stirring. Ammonium persulfate (0.8 g) was added together with water (3.1 g). 2-Ethylhexyl acrylate, methyl methacrylate, diacetone acrylamide, and adipic dihydrazide (total weight 174.7 g) were slowly added to the reactor within 120 minutes, while dropping a mixture of ammonium persulfate (1.1 g) and water (20 g). After the dropping was completed, it was kept warm for 60 minutes. Then it was cooled to 40 °C, 2 g of adipic dihydrazide was added, and a fungicide (1.5 g) was added.

[0057] The solid content of the final emulsion is 41%, the particle size is 65 nm, and the pH is 8.01.

[0058] Example 4 Charge 309.7 g of deionized water and 150 g of S-678 into a 2 L reactor. At room temperature, add 40.4 g of ammonia water solution (25% aqueous solution) to the reaction kettle with stirring within 5 minutes. Heat the reaction kettle to 80 °C and stir for 120 min at 80 °C. Then cool the solution to room temperature and filter the product. The pH of the final alkali-soluble resin solution is about 8.1 and the solid content is about 30 wt%.

[0059] Charge deionized water (184.8 g), alkali-soluble resin solution (145.7 g), and SR-10 (3.9 g) into a 1 L reactor and heat to 85 °C with stirring. Add ammonium persulfate (0.8 g) together with water (3.1 g). Slowly add 2-ethylhexyl acrylate, methyl methacrylate, ethylene glycol bis(acetoacetate methacrylate), and adipic dihydrazide (total weight 174.7 g) to the reactor within 120 minutes, while dropping a mixture of ammonium persulfate (1.1 g) and water (20 g). After the dropping is completed, keep the temperature for 60 minutes. Then cool to 40 °C, add 2 g of adipic dihydrazide, and add 1.5 g of fungicide.

[0060] The solid content of the final emulsion is 41%, the particle size is 65 nm, and the pH is 8.01.

[0061] Comparative Example 1 Charge 309.7 g of deionized water and 150 g of S-678 into a 2 L reactor. At room temperature, add 40.4 g of ammonia water solution (25% aqueous solution) to the reaction kettle with stirring within 5 minutes. Heat the reaction kettle to 80 °C and stir for 120 min at 80 °C. Then cool the solution to room temperature and filter the product. The pH of the final alkali-soluble resin solution is about 8.1 and the solid content is about 30 wt%.

[0062] Charge deionized water (184.8 g), alkali-soluble resin solution (145.7 g), and SR-10 (3.9 g) into a 1 L reactor and heat to 85 °C with stirring. Add ammonium persulfate (0.8 g) together with water (3.1 g). Slowly add butyl acrylate and methyl methacrylate (total weight 174.7 g) to the reactor within 120 minutes, while dropping a mixture of ammonium persulfate (1.1 g) and water (20 g). After the dropping is completed, keep the temperature for 60 minutes. Then cool to 40 °C, add 2 g of adipic dihydrazide, and add 1.5 g of fungicide.

[0063] The solid content of the final emulsion is 41%, the particle size is 65 nm, and the pH is 8.01.

[0064] Comparative Example 2 309.7 g of deionized water and 150 g of S-678 were charged into a 2 L reactor. At room temperature, 40.4 g of an aqueous ammonia solution (25% aqueous solution) was added to the reaction kettle with stirring within 5 minutes. The reaction kettle was heated to 80 °C and stirred at 80 °C for 120 min. Then the solution was cooled to room temperature and the product was filtered. The pH of the final alkali-soluble resin solution was about 8.1 and the solid content was about 30 wt%.

[0065] 184.8 g of deionized water, 145.7 g of an alkali-soluble resin solution, and 3.9 g of SR-10 were charged into a 1 L reactor and heated to 85 °C with stirring. Ammonium persulfate (0.8 g) was added together with water (3.1 g). 2-Ethylhexyl acrylate and methyl methacrylate (total weight 174.7 g) were slowly added to the reactor within 120 minutes, while a mixture of ammonium persulfate (1.1 g) and water (20 g) was added dropwise. After the addition was completed, the mixture was kept warm for 60 minutes. Then it was cooled to 40 °C, 2 g of adipic dihydrazide was added, and 1.5 g of a bactericide was added.

[0066] The solid content of the final emulsion was 41%, the particle size was 65 nm, and the pH was 8.01.

[0067] It should be noted that: The synthesis formula compositions described in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0068] Table 1. Synthesis formula composition of the waterborne wood lacquer emulsion

[0069] It should be noted that: In Table 1, BA is butyl acrylate, 2-EHA is 2-ethylhexyl acrylate, MMA is methyl methacrylate, DAAM is diacetone acrylamide, AAEMA is ethylene glycol bis(acetoacetate) methacrylate, and ADH is adipic dihydrazide.

[0070] Performance testing The acrylic emulsions obtained from Examples 1-4 and Comparative Examples 1-2 above were formulated into varnishes according to the formula in Table 2 below.

[0071] Table 2 Formulation composition of the acrylic emulsion wood lacquer

[0072] Film detection: The hardness (pencil scratch) was measured according to "GB / T 6739-1996 Determination method for pencil hardness of film coatings". The gloss was measured according to "GB / T 9754-2007 Determination of 20°, 60° and 85° specular gloss of paints and varnishes - Paints without metallic pigments" (with 60° as the standard). Prepare alcohol, vinegar, tea, and boiling water according to GB / T 23999—2009 "Waterborne Wood Coatings for Interior Decoration and Fitment"; evaluate the boiling water resistance, alcohol resistance, and stain resistance of the paint film surface according to GB / T 4893.1—2005 "Determination of Resistance of Furniture Surfaces to Cold Liquids".

[0073] The specific varnish test results are shown in Table 3 Table 3. Performance Test Results of Wood Coatings

[0074] It should be noted that the pencil hardness increases successively from 4B to 6H; for the stain resistance of the paint film surface: grade 1 is the best and grade 5 is the worst.

[0075] The above experimental results show that a high-gloss and high-hardness acrylic emulsion can be prepared by introducing solid acrylic resin.

[0076] The above are only embodiments of the present invention. Common knowledge such as specific structures and characteristics known in the art are not described in detail herein. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention pertains before the filing date or the priority date, can know all the existing technologies in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, complete and implement this solution in combination with their own abilities. Some typical well-known structures or well-known methods should not be an obstacle for those of ordinary skill in the art to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent.

Claims

1. A self-crosslinking wood lacquer emulsion, characterized in that Comprising: An alkali-soluble solid resin and an emulsion polymer; Wherein, the weight-average molecular weight of the alkali-soluble solid resin is 2000 - 14000, and the acid value is 40 - 260; The content of the alkali-soluble solid resin is 10 - 80% based on the total dry weight of the emulsion, and the theoretical acid value of the emulsion is 10 - 70; The emulsion polymer is synthesized from a mixture comprising at least one hydrophobic monoethylenically unsaturated monomer and at least one hydrophilic monoethylenically unsaturated monomer.

2. The self-crosslinking wood lacquer emulsion according to claim 1, wherein The alkali-soluble acrylic resin uses any one of acrylic resin S-120, acrylic resin S-60, acrylic resin S-80, and acrylic resin S-678.

3. The self-crosslinking wood lacquer emulsion according to claim 1, wherein The alkali-soluble acrylic resin is made water-soluble by a neutralizing agent; The neutralizing agent uses any one or a mixture of sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium acetate, sodium pyrophosphate, sodium carbonate, ammonia water, hydrochloric acid, phosphoric acid, formic acid, acetic acid, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, and glycine.

4. The self-crosslinking wood lacquer emulsion according to claim 1, wherein The hydrophobic monoethylenically unsaturated monomer uses any one or a mixture of (meth)acrylate monomers, (meth)acrylonitrile monomers, styrene monomers, vinyl alkanoate monomers, and monoethylenically unsaturated di- and tricarboxylate monomers.

5. The self-crosslinking wood lacquer emulsion according to claim 4, wherein The (meth)acrylate monomer uses any one or a mixture of C1 - C19-alkyl (meth)acrylates; The styrene monomer uses any one or a mixture of unsubstituted styrene or C1 - C6-alkyl-substituted styrene; The vinyl alkanoate monomer uses any one or a mixture of vinyl esters of C2 - C11 alkanoic acids; The monoethylenically unsaturated di- and tricarboxylate monomers use any one or a mixture of full esters of monoethylenically unsaturated dicarboxylic acids and tricarboxylic acids.

6. The self-crosslinking wood lacquer emulsion according to claim 1, characterized in that, The content of the hydrophobic monoethylenically unsaturated monomer is 85% or more based on the total weight of the emulsion polymer.

7. The self-crosslinking wood lacquer emulsion according to claim 1, characterized in that, The hydrophilic monoethylenically unsaturated monomer uses a monoethylenically unsaturated monomer containing at least one functional group selected from carboxyl, carboxylic anhydride, sulfonic acid, phosphoric acid, hydroxyl, and amide.

8. The self-crosslinking wood lacquer emulsion according to claim 1, characterized in that, The mixture may further contain one or more crosslinking monomers; The emulsion further includes an initiator, an emulsifier, and a bactericide; Wherein the initiator uses one of peroxide thermal initiators, persulfate thermal initiators, and azo compound thermal initiators; The emulsifier is a reactive surfactant, and the emulsifier contains at least one ethylenically unsaturated functional group.

9. A preparation method of a self-crosslinking wood lacquer emulsion, characterized in that, Including the following steps: Put deionized water and the alkali-soluble solid resin into a reaction kettle; Add the ammonia water solution to the reaction kettle within 5 - 10 minutes under stirring, heat the reaction kettle to 70 - 90 °C and stir for 1.5 - 3 hours; After cooling to room temperature, filter to obtain an alkali-soluble resin solution; Put deionized water, the alkali-soluble resin solution, and the emulsifier into a reaction kettle, stir and heat to 80 - 90 °C; After adding the initiator, slowly add the mixture to the reaction kettle within 2 - 3 hours, and simultaneously dropwise add the initiator; Cool the reaction kettle to 30 - 50 °C, and sequentially add the crosslinking monomer and the bactericide to obtain a self-crosslinking wood lacquer emulsion.

10. Application of a self-crosslinking wood lacquer emulsion, characterized in that, An acrylic emulsion wood paint is prepared using a self-crosslinking wood paint emulsion as a raw material.

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