Modified acrylic emulsion as well as preparation method and application thereof

Abstract

The invention relates to a modified acrylic emulsion as well as a preparation method and application thereof. The water-based acrylic resin comprises the following components in percentage by weight: 30 to 40 percent of acrylate monomer and / or methacrylate monomer, 2 to 4 percent of hydroxyl acrylate monomer, 0.2 to 0.8 percent of polymerizable unsaturated acid monomer, 0.4 to 1.5 percent of crosslinking monomer, 0.6 to 0.8 percent of monomer containing N heterocyclic ring, 0.4 to 1 percent of organic silicon monomer, 0.5 to 1.5 percent of polymerizable emulsifier, 0.08 to 0.16 percent of persulfate, 0.02 to 0.08 percent of pH buffering agent, 0.3 to 1 percent of neutralizer and the balance of water. And the balance of deionized water. The water-based bi-component polyurethane wood lacquer prepared from the modified acrylic emulsion provided by the invention has the advantages of good adhesive force on a melamine board, fast hardness increase, very excellent anti-adhesion effect, better water resistance, chemical resistance and stain resistance, and is very suitable for water-based coating of the melamine board.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic paints, and in particular to a modified acrylic emulsion and a preparation method and application thereof. Background Art

[0002] Melamine board, also known as melamine impregnated film paper veneer artificial board, is known for its excellent hardness, stain resistance, heat resistance and wear resistance. In addition, the production process is simple and the raw materials are easily available, showing significant cost-effectiveness. It has been widely used in the fields of office and indoor furniture and interior architecture. However, the board is usually monotonous in color and has minor defects on the surface. It is difficult to meet the high requirements of the terminal market for color richness and texture diversity. Therefore, more and more melamine boards are beginning to be painted to improve their appearance. Given the smooth surface and extremely high hardness of melamine boards, conventional coatings are difficult to adhere effectively. At present, the main types of coatings used are solvent-based two-component polyurethane coatings and UV coatings. However, given that these solvent-based coatings contain high levels of volatile organic compounds (VOCs), their use is increasingly restricted. In contrast, water-based coatings are an ideal alternative due to their low VOC content. However, water-based paint uses water as a dispersion medium, and due to the high surface tension of water, it is difficult to adhere to melamine boards. At the same time, the latent heat of evaporation of water is high, resulting in a slower drying speed than solvent-based paint, which in turn affects the rapid improvement of paint film performance and coating efficiency. Therefore, in order to successfully apply water-based paint to the coating of melamine boards, the first task is to solve the adhesion problem, and the second is to improve the drying speed and overall coating efficiency.

[0003] Chinese invention patent CN102993939B discloses a polyurethane primer for melamine board. In the primer, hydroxy acrylic resin and alkyd resin are used in combination, so that the melamine board can be directly sprayed without sanding. Although alkyd resin can significantly improve adhesion, it will affect the drying speed. In addition, the hydroxy acrylic resin and alkyd resin used in the primer are both solvent-based resins with a high overall VOC content. Chinese invention patent CN102220082B discloses a two-component low-VOC oily polyurethane primer, which will result in poor adhesion when used on melamine board and is easy to peel off after construction. Summary of the invention

[0004] The first aspect of the present invention provides a modified acrylic emulsion, which comprises, by weight percentage, 20-50% of an acrylic acid ester monomer and / or a methacrylic acid ester monomer, 1-4% of a hydroxy acrylic acid ester monomer, 0.1-0.8% of a polymerizable unsaturated acid monomer, 0.1-1.5% of a cross-linking monomer, 0.6-2% of a monomer containing an N heterocycle, 0.4-2% of an organic silicon monomer, 0.2-1.5% of a polymerizable emulsifier, 0.01-0.16% of a persulfate, 0.01-0.08% of a pH buffer, and 0.1-1% of a neutralizer; the balance is made up of deionized water.

[0005] Preferably, the components include: 30-40% of acrylate monomer and / or methacrylate monomer, 2-4% of hydroxy acrylate monomer, 0.2-0.8% of polymerizable unsaturated acid monomer, 0.4-1.5% of cross-linking monomer, 0.6-0.8% of monomer containing N heterocycle, 0.4-1% of organosilicon monomer, 0.5-1.5% of polymerizable emulsifier, 0.08-0.16% of persulfate, 0.02-0.08% of pH buffer, and 0.3-1% of neutralizer; the balance is made up by deionized water.

[0006] The polymerizable unsaturated acid monomer includes at least one of methacrylic acid, acrylic acid, β-carboxyethyl acrylate, itaconic acid, and 2-hydroxyethyl methacrylate phosphate.

[0007] Preferably, the polymerizable unsaturated acid monomer includes β-carboxyethyl acrylate.

[0008] The amount of the cross-linking monomer added to the modified acrylic emulsion is 0.6-1.5 wt %.

[0009] Preferably, the amount of the cross-linking monomer added to the modified acrylic emulsion is 0.8-1.5 wt %.

[0010] Preferably, the amount of the hydroxy acrylate monomer added to the modified acrylic emulsion is 2-3%.

[0011] The weight ratio of the monomer containing N heterocycle to the organosilicon monomer is 1:(0.5-1.2).

[0012] Preferably, the weight ratio of the N-heterocyclic monomer to the organosilicon monomer is 1:(0.8-1.2).

[0013] The research in this application found that the weight ratio of the monomer containing N heterocycle to the silicone monomer is 1: (0.5-1.2), which can improve the anti-adhesion and adhesion of the paint film prepared from the emulsion. It may be that the silicone monomer can be grafted onto the polymer molecular chain during the reaction. Due to the low surface energy and heat resistance of silicon, and the interaction with the high-polarity N heterocycle functional monomer, it interacts with the polar groups in melamine, effectively improving the adhesion on the melamine board.

[0014] The methacrylate monomer includes at least one of methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, and n-butyl methacrylate.

[0015] The acrylic acid ester monomer includes at least one of n-butyl acrylate, isooctyl acrylate and lauryl acrylate.

[0016] The hydroxy acrylate monomer includes at least one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate.

[0017] The cross-linking monomer includes at least one of diacetone acrylamide, adipic dihydrazide, glycidyl methacrylate, N-(isobutyloxy)methacrylamide, and ethyl acetoacetate methacrylate.

[0018] Preferably, the cross-linking monomer comprises diacetone acrylamide and adipic dihydrazide, and the weight ratio of diacetone acrylamide to adipic dihydrazide is 1:(0.1-0.8).

[0019] Preferably, the weight ratio of diacetone acrylamide to adipic dihydrazide is 1:(0.4-0.8).

[0020] The monomer containing an N heterocycle includes a vinyl monomer containing an N heterocycle.

[0021] Preferably, the vinyl monomer containing an N-heterocyclic ring includes at least one of acryloylmorpholine, N-vinylimidazole, N-vinylpiperidone, N-vinylcarbazole and N-vinylacetamide.

[0022] Preferably, the organic silicon monomer includes at least one of vinyl trimethoxy silane, vinyl triethoxy silane and γ-(methacryloyloxy)propyl trimethoxy silane.

[0023] The polymerizable emulsifier includes an allyl group-containing reactive emulsifier.

[0024] Preferably, the allyl-containing reactive emulsifier is selected from at least one of the following models: Clariant EmulsogenAPG 2019, EDICO SR-10, and Sanyo Chemical ELEMINOL JS-20.

[0025] The persulfate includes at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.

[0026] The pH buffer includes at least one of sodium bicarbonate, potassium bicarbonate, and disodium hydrogen phosphate.

[0027] The neutralizing agent includes at least one of dilute ammonia water and 2-amino-2-methyl-1-propanol.

[0028] The second aspect of the present invention provides a method for preparing a modified acrylic emulsion, comprising the following steps:

[0029] 20-40 wt% of deionized water, 40-60 wt% of polymerizable emulsifier, and 60-75 wt% of persulfate are mixed evenly, and then 40-55 wt% of acrylate monomer, 80-92 wt% of methacrylate monomer, and 10-25 wt% of polymerizable unsaturated acid monomer are added and mixed evenly to obtain a first monomer pre-emulsion;

[0030] 5-15 wt% of deionized water, 15-25 wt% of polymerizable emulsifier, and 20-35 wt% of persulfate are mixed evenly, and remaining acrylate monomers, remaining methacrylate monomers, remaining polymerizable unsaturated acid monomers, hydroxy acrylate monomers, N-heterocyclic monomers, 50-80 wt% of crosslinking monomers, and silicone monomers are added and mixed evenly to obtain a second monomer pre-emulsion;

[0031] The remaining deionized water, the remaining polymerizable emulsifier, and the pH buffer are mixed evenly to obtain a primer solution;

[0032] Adding the remaining persulfate and the first monomer pre-emulsion accounting for 2-8 wt % of the total amount of the first monomer pre-emulsion to the primer solution, and mixing them evenly to obtain a seed emulsion;

[0033] The remaining first monomer pre-emulsion is added dropwise to the seed emulsion, and after being evenly mixed, the second monomer pre-emulsion is added dropwise to react, and the remaining cross-linking monomer is added, and a neutralizer is added to adjust the pH to 7-8 to obtain a modified acrylic emulsion.

[0034] Preferably, the preparation method of the modified acrylic emulsion comprises the following steps:

[0035] 20-32 wt% of deionized water, 45-60 wt% of polymerizable emulsifier, and 62-72 wt% of persulfate are mixed evenly, and then 45-55 wt% of acrylate monomer, 85-92 wt% of methacrylate monomer, and 12-22 wt% of polymerizable unsaturated acid monomer are added and mixed evenly to obtain a first monomer pre-emulsion;

[0036] 7-15 wt% of deionized water, 18-25 wt% of polymerizable emulsifier, and 25-35 wt% of persulfate are mixed evenly, and remaining acrylate monomers, remaining methacrylate monomers, remaining polymerizable unsaturated acid monomers, hydroxy acrylate monomers, N-heterocyclic monomers, 60-70 wt% of crosslinking monomers, and silicone monomers are added and mixed evenly to obtain a second monomer pre-emulsion;

[0037] The remaining deionized water, the remaining polymerizable emulsifier, and the pH buffer are mixed evenly to obtain a primer solution;

[0038] Adding the remaining persulfate and the first monomer pre-emulsion accounting for 2-8 wt % of the total amount of the first monomer pre-emulsion to the primer solution, and mixing them evenly to obtain a seed emulsion;

[0039] The remaining first monomer pre-emulsion is added dropwise to the seed emulsion, and after being evenly mixed, the second monomer pre-emulsion is added dropwise to react, and the remaining cross-linking monomer is added, and a neutralizer is added to adjust the pH to 7-8 to obtain a modified acrylic emulsion.

[0040] The remaining first monomer pre-emulsion liquid is added dropwise for 3-4 hours, and the remaining first monomer pre-emulsion liquid is added dropwise for 1-2 hours.

[0041] Preferably, the remaining first monomer pre-emulsion liquid is added dropwise for 3-3.5 hours, and the remaining second monomer pre-emulsion liquid is added dropwise for 1-1.5 hours.

[0042] The weight ratio of the first monomer pre-emulsion to the second monomer pre-emulsion is (1.5-4):1.

[0043] Preferably, the weight ratio of the first monomer pre-emulsion to the second monomer pre-emulsion is (2-3):1.

[0044] More preferably, the weight ratio of the first monomer pre-emulsion to the second monomer pre-emulsion is (2-2.5):1.

[0045] The reaction temperature is 75-85°C and the reaction time is 0.5-1.5.

[0046] Preferably, the reaction temperature is 80-84°C and the reaction time is 0.8-1.5.

[0047] The third aspect of the present invention provides an application of a method for preparing a modified acrylic emulsion, which is used for preparing a resin emulsion in a two-component polyurethane wood paint, wherein the content of the modified acrylic emulsion in the resin emulsion is 50-80wt%.

[0048] The applicant has found that modified acrylic emulsion is used for the preparation of resin emulsion in two-component polyurethane wood paint. The two-component crosslinking and self-crosslinking of hydroxyl and isocyanate curing agent can achieve a certain crosslinking density without affecting the activation period and drying speed. Suitable unsaturated acid monomers and functional monomers are selected to provide adhesion, and organic silicon monomers are introduced to improve early anti-adhesion. A two-step dropwise polymerization process is adopted and a suitable mass ratio is selected. The monomers containing functional groups are polymerized in the second step, which can maximize the effect of these functional groups on adhesion, dryness, and anti-adhesion. The water-based two-component polyurethane wood paint prepared using the modified acrylic emulsion is used for the coating of melamine boards. It has good adhesion, long application period, fast drying and excellent early anti-adhesion. In addition, it has low use cost and high production efficiency, which has positive significance for promoting the water-based coating of melamine boards.

[0049] Preferably, the content of the modified acrylic emulsion in the resin emulsion is 50-70wt%.

[0050] Beneficial Effects

[0051] 1. This application simultaneously adds hydroxyl monomers and cross-linking monomers and is applied to two-component polyurethane paints. Combined with self-cross-linking, it can achieve a certain cross-linking density, thereby improving adhesion, hardness, chemical resistance, stain resistance and weather resistance, without affecting the activation period and drying speed.

[0052] 2. The amount of cross-linking monomer added to the modified acrylic emulsion is limited to 0.6-1.5wt%, and the amount of hydroxy acrylate monomer added to the modified acrylic emulsion is limited to 2-3%, which can further improve the activation period and drying speed of the paint prepared from the emulsion.

[0053] 3. The weight ratio of the monomer containing N heterocycle to the organosilicon monomer is 1:(0.5-1.2), which can improve the anti-adhesion and adhesion of the paint film prepared from the emulsion.

[0054] 4. The present application adopts a two-step dropwise polymerization process, adds β-carboxyethyl acrylate, and limits the weight ratio of the first monomer pre-emulsion to the second monomer pre-emulsion to (1.5-4):1, which can satisfy the requirement of the emulsion.

[0055] The water-based coating of the paint prepared by the liquid on the melamine board has an adhesion of level 1 and an anti-blocking property of level 5.

[0056] 5. The modified acrylic emulsion prepared in the present application is used in two-component polyurethane wood paint, and the prepared paint film has excellent aging resistance, low use cost and high production efficiency. DETAILED DESCRIPTION

[0057] Example 1, Comparative Examples 1-7

[0058] A modified acrylic emulsion, the components used are shown in Table 1, in addition to the components listed in Table 1, it also contains a pH buffer (sodium bicarbonate), a neutralizer (2-amino-2-methyl-1-propanol) and deionized water.

[0059] Table 2 (parts by weight) shows the components of the first monomer pre-emulsion.

[0060] Table 3 (parts by weight) shows the components of the second monomer pre-emulsion.

[0061] Table 4 (parts by weight) shows the components of the primer.

[0062] Table 1

[0063] Components Abbreviation Methyl Methacrylate (Methacrylate Monomer) MMA n-Butyl acrylate(Acrylate monomer) BA Acrylic acid (hydroxy acrylate monomer) AA β-Carboxyethyl acrylate (polymerizable unsaturated acid monomer) β-CEA Hydroxyethyl acrylate(Hydroxyacrylate monomer) HEA Diacetone acrylamide (cross-linking monomer) DAAM Adipic acid hydrazide (cross-linking monomer) ADH Acryloylmorpholine (monomer containing N heterocyclic ring) ACMO Vinyltriethoxysilane (silicone monomer) A-151 Polymerizable emulsifier (polymerizable emulsifier) JS-20 (Japanese Sanyo Chemical ELEMINOL) Sodium Persulfate (Persulfate) SPS

[0064] Table 2

[0065]

[0066] Table 3

[0067]

[0068]

[0069] Table 4

[0070]

[0071] The preparation method of the modified acrylic emulsion of Example 1, Comparative Examples 1-4, and Comparative Examples 6-7 is as follows:

[0072] S1: As shown in Table 2, deionized water, polymerizable emulsifier, and persulfate are mixed, stirred until completely dissolved, and then the remaining components are added and mixed evenly to obtain a first monomer pre-emulsion;

[0073] S2: As shown in Table 3, deionized water, polymerizable emulsifier, and persulfate are mixed, stirred until completely dissolved, and the remaining components are added and mixed evenly to obtain a second monomer pre-emulsion;

[0074] S3: As shown in Table 4, the primer components are mixed evenly to obtain a primer;

[0075] S4: Raise the temperature to 75° C., add 0.04 parts of SPS and the first monomer pre-emulsion accounting for 5 wt % of the total amount of the first monomer pre-emulsion into the primer, mix well, and keep warm for 20 minutes to obtain a seed emulsion;

[0076] S5: uniformly add the remaining first monomer emulsion dropwise to the seed emulsion within 3.5 hours, control the temperature at 82°C, and keep warm for 30 minutes. Then uniformly add the second monomer emulsion dropwise to the reactor within 1.5 hours, control the temperature in the reactor at 82°C, and start cooling after keeping warm for 1 hour. Add ADH. When the temperature in the reactor drops to 45°C, add a neutralizer to adjust the pH to 7. After filtering, the modified acrylic emulsion is obtained.

[0077] The preparation method of the modified acrylic emulsion in Comparative Example 5 is the same as that in Example 1, except that ADH is not added.

[0078] Performance Testing Methods

[0079] The modified acrylic emulsion prepared in the examples and comparative examples was used to prepare the resin emulsion in the two-component polyurethane wood paint. A water-based two-component polyurethane wood paint was prepared according to the formula (parts by weight) in Table 5, and component A (resin emulsion) and component B were evenly mixed in a ratio of n(-NCO) / n(-OH)=1.3:1. The paint was then sprayed on a melamine board and baked at 40°C for 4 hours. The paint was then dried at room temperature for 12 hours and tested according to the following method. The test results are shown in Table 6.

[0080] Paint film drying speed: tested according to the method provided in GB / T 1728-2020 "Determination of drying time of paint film and putty film".

[0081] Adhesion: Tested in accordance with the national standard GB / T9286-1998 "Scratch test for paint and varnish films".

[0082] Hardness: Tested in accordance with the national standard GB / T6739-2006 "Paint and varnish pencil method for determination of paint film hardness".

[0083] Anti-blocking property: Tested in accordance with the national standard GB / T 23982-2009 "Determination of Anti-blocking Property of Wood Coatings". Score is given based on the adhesion, with 5 points representing the best and 1 point representing the worst.

[0084] Water resistance: The test is conducted in accordance with the national standard GB / T1733-1993 "Determination of water resistance of paint films", with blistering and severe discoloration of the paint film as the termination criteria.

[0085] Alcohol resistance: The test is conducted in accordance with the national standard GB / T 4893.1-2005 “Determination of cold liquid resistance of furniture surface”, and the test liquid is 50% ethanol.

[0086] Pollution resistance: The test is carried out in accordance with the national standard GB / T 4893.1-2005 "Determination of cold liquid resistance of furniture surface", and the test liquids are vinegar and green tea.

[0087] Pot life: Mix component A and component B and place them in a 25°C environment. The end point is when the viscosity increases to the point where normal spraying is impossible or the performance of the paint film changes significantly.

[0088] Artificial aging test: The test is carried out in accordance with the national standard GB / T 1865-2009 "Artificial weathering and artificial radiation exposure of paints and varnishes to filtered xenon arc radiation".

[0089] Table 5

[0090]

[0091] Performance test data

[0092] Table 6

[0093]

[0094] From the results in Table 6, it can be seen that by comparing Example 1 and Comparative Examples 5-6, the introduction of self-crosslinking monomers can increase the crosslinking density, improve adhesion, hardness and compressive resistance, but when the amount of self-crosslinking monomers is too much, the performance increase is not obvious, and too much ADH will affect the activation period; by comparing Example 1 and Comparative Example 7, it can be seen that increasing the hydroxyl content will cause the paint film to be excessively crosslinked and the cohesive force is large and cannot be effectively released, resulting in decreased adhesion. Excessive use of curing agent will slow down the drying speed and increase the cost; by comparing Example 1 and Comparative Example 1, it can be seen that the unsaturated acid monomer has a greater effect on adhesion. Compared with acrylic acid, β-carboxyethyl acrylate has a longer carboxyl side chain, and the carboxyl group is more likely to interact with the substrate, so the adhesion is better; by comparing Example 1 and Comparative Example 2, it can be seen that the silicone monomer A-151 During the reaction, it can be grafted onto the polymer molecular chain. Due to the low surface energy and heat resistance of silicon, the introduction of a small amount of silicone monomer can significantly improve the anti-adhesion property. By comparing Example 1 and Comparative Example 3, it can be seen that the N heterocyclic functional monomer ACMO can improve the adhesion on the melamine board. This may be because the N heterocyclic ring is a polar group and can interact with the polar groups in melamine. By comparing Example 2 and Comparative Example 4, it can be seen that the mass ratio of the monomers in the two-step polymerization will have a greater impact on the adhesion and drying speed. When the total monomer dosage of the emulsion remains unchanged, the mass of the monomers in the first step is more than that in the second step, and the functional monomers are polymerized in the second step, the drying and adhesion of the emulsion will be better. In this way, these monomers can be gathered together to maximize the role of the specialized groups on these monomers.

[0095] In summary, the water-based two-component polyurethane wood paint prepared by the modified acrylic emulsion provided by the present invention has good adhesion on melamine boards, fast hardness increase, excellent anti-adhesion effect, and good water resistance, chemical resistance and stain resistance. It is very suitable for water-based coating of melamine boards with high requirements for drying speed, compression resistance, anti-adhesion and stain resistance.

Claims

1. A modified acrylic emulsion, characterized in that: Calculated by weight percentage, the components include: 30-40% of acrylate monomer and / or methacrylate monomer, 2-4% of hydroxy acrylate monomer, 0.2-0.8% of polymerizable unsaturated acid monomer, 0.4-1.5% of cross-linking monomer, 0.6-0.8% of monomer containing N heterocycle, 0.4-1% of organic silicon monomer, 0.5-1.5% of polymerizable emulsifier, 0.08-0.16% of persulfate, 0.02-0.08% of pH buffer, 0.3-1% of neutralizer, and deionized water makes up the balance.

2. The modified acrylic emulsion according to claim 1, characterized in that The polymerizable unsaturated acid monomer includes at least one of methacrylic acid, acrylic acid, β-carboxyethyl acrylate, itaconic acid, and 2-hydroxyethyl methacrylate phosphate.

3. The modified acrylic emulsion according to claim 2, characterized in that: The amount of the cross-linking monomer added to the modified acrylic emulsion is 0.6-1.5 wt %.

4. The modified acrylic emulsion according to claim 3, characterized in that: The amount of the hydroxy acrylate monomer added to the modified acrylic emulsion is 2-3%.

5. The modified acrylic emulsion according to claim 4, characterized in that: The weight ratio of the monomer containing N heterocycle to the organosilicon monomer is 1:(0.5-1.2).

6. The modified acrylic emulsion according to claim 5, characterized in that: The monomer containing an N heterocycle includes a vinyl monomer containing an N heterocycle.

7. A method for preparing the modified acrylic emulsion according to any one of claims 1 to 6, characterized in that: The following steps are involved: 20-40 wt% of deionized water, 40-60 wt% of polymerizable emulsifier, and 60-75 wt% of persulfate are mixed evenly, and then 40-55 wt% of acrylate monomer, 80-92 wt% of methacrylate monomer, and 10-25 wt% of polymerizable unsaturated acid monomer are added and mixed evenly to obtain a first monomer pre-emulsion; 5-15 wt% of deionized water, 15-25 wt% of polymerizable emulsifier, and 20-35 wt% of persulfate are mixed evenly, and remaining acrylate monomers, remaining methacrylate monomers, remaining polymerizable unsaturated acid monomers, hydroxy acrylate monomers, N-heterocyclic monomers, 50-80 wt% of crosslinking monomers, and silicone monomers are added and mixed evenly to obtain a second monomer pre-emulsion; The remaining deionized water, the remaining polymerizable emulsifier, and the pH buffer are mixed evenly to obtain a primer solution; Adding the remaining persulfate and the first monomer pre-emulsion accounting for 2-8 wt % of the total amount of the first monomer pre-emulsion to the primer solution, and mixing them evenly to obtain a seed emulsion; The remaining first monomer pre-emulsion is added dropwise to the seed emulsion, and after being evenly mixed, the second monomer pre-emulsion is added dropwise to react, and the remaining cross-linking monomer is added, and a neutralizer is added to adjust the pH to 7-8 to obtain a modified acrylic emulsion.

8. The method for preparing the modified acrylic emulsion according to claim 7, characterized in that: The remaining first monomer pre-emulsion liquid is added dropwise for 3-4 hours, and the remaining first monomer pre-emulsion liquid is added dropwise for 1-2 hours.

9. The method for preparing the modified acrylic emulsion according to claim 7, characterized in that: The weight ratio of the first monomer pre-emulsion to the second monomer pre-emulsion is (1.5-4):

1.

10. An application of the method for preparing modified acrylic emulsion according to claim 7, characterized in that: The invention is applied to the preparation of resin emulsion in two-component polyurethane wood paint, wherein the content of the modified acrylic emulsion in the resin emulsion is 50-80wt%.

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