Polyurethane modified acrylic emulsion, preparation method and floor paint

Abstract

The invention discloses a polyurethane modified acrylic emulsion, a preparation method and floor paint. The polyurethane modified acrylic emulsion comprises deionized water, methyl methacrylate, butyl acrylate, a polyurethane curing agent, n-butyl methacrylate, a crosslinking monomer, a hydroxy acrylic monomer, acrylic acid, styrene, an emulsifier, a pH regulator, an adhesion promoter and an initiator. According to the invention, through the matching of the soft monomer and the hard monomer, the glass transition temperature of the polyurethane modified acrylic emulsion is 30-50 DEG C, when the glass transition temperature of the emulsion is within the range, the emulsion has relatively strong rigidity and can endow a paint film with relatively high hardness, wear resistance and other properties, and the acrylic emulsion has good weatherability, so that the paint film has good weather resistance. The strong rigidity of the emulsion can further enhance the natural environment erosion resistance of an emulsion paint film, so that the hardness, wear resistance, weather resistance and other properties of the floor paint containing the emulsion can be remarkably improved, and the adhesive force of the floor paint to a base material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of acrylic emulsions, and in particular to a polyurethane modified acrylic emulsion, a preparation method and a floor paint. Background Art

[0002] Polyurethane modified acrylic emulsion is an emulsion with special properties formed by chemical bonds or physical blending of two types of polymers, polyurethane and acrylate. This emulsion combines the respective advantages of polyurethane and acrylate. Polyurethane modified acrylic emulsion has excellent chemical resistance and water resistance, as well as good mechanical properties.

[0003] Floor paint was first invented by Germany in 1934. It is mainly made of a variety of different substances such as oil, wood, pigment, solvent, etc. through many production processes such as mixing, dissolving, and dispersing. It can be divided into decorative floor paint, heavy anti-corrosion floor paint, heavy resistant floor paint, etc. It has the characteristics of bright, real, beautiful, wear-resistant, waterproof, and anti-corrosion. However, the existing floor paint has general wear resistance and weather resistance. There are few applications in the existing technology that use polyurethane modified acrylic emulsion in floor paint to improve the wear resistance and weather resistance of floor paint.

[0004] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] The purpose of the present invention is to provide a polyurethane modified acrylic emulsion, a preparation method and a floor paint, aiming to solve the problem that there are few applications of polyurethane modified acrylic emulsion in floor paint to improve the wear resistance, weather resistance and other properties of floor paint in the prior art.

[0006] To achieve the above object, the solution provided by the present invention is:

[0007] The present invention provides a polyurethane modified acrylic emulsion, comprising the following components in parts by weight:

[0008] 1470 parts of deionized water, 500-540 parts of methyl methacrylate, 220-260 parts of butyl acrylate, 100-200 parts of polyurethane curing agent, 78-82 parts of n-butyl methacrylate, 75 parts of cross-linking monomer, 57-62 parts of hydroxy acrylic monomer, 23-27 parts of acrylic acid, 18-23 parts of styrene, 10.3-12.3 parts of emulsifier, 12 parts of pH adjuster, 4-6 parts of adhesion promoter, and 4 parts of initiator.

[0009] Optionally, the cross-linking monomer includes at least one of diacetone acrylamide and adipic acid dihydrazide.

[0010] Optionally, the emulsifier includes at least one of sodium dodecyl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

[0011] Optionally, the pH adjuster includes at least one of ammonia water, sodium hydroxide and sodium bicarbonate.

[0012] Optionally, the adhesion promoter includes ethylene urea ethoxy methacrylate.

[0013] Optionally, the initiator includes at least one of ammonium persulfate, potassium persulfate oxide, and sodium persulfate.

[0014] Optionally, the weight of the polyurethane curing agent accounts for 3% to 5% of the total weight of the polyurethane modified acrylic emulsion.

[0015] The present invention also provides a method for preparing the polyurethane modified acrylic emulsion, comprising the following steps:

[0016] S001. Add 0.3 parts of emulsifier and 1000 parts of deionized water to the reactor, stir and mix to obtain a base liquid;

[0017] S002. Add 10 to 12 parts of an emulsifier and 350 parts of deionized water to an emulsifying tank, stir and mix, then add styrene, methyl methacrylate, butyl acrylate, n-butyl methacrylate, hydroxy acrylic acid monomer, acrylic acid, an adhesion promoter and 50 parts of a cross-linking monomer, stir and mix to obtain a pre-emulsion;

[0018] S003. Add 1 part of initiator and 10 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution A;

[0019] S004. Add 3 parts of initiator and 30 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution B;

[0020] S005. The temperature of the reactor was raised to 85 ℃ ~ 87 ℃, and the initiator solution A and the pre-emulsion were added to the reactor. The pre-emulsion was kept warm for 13 to 16 minutes before preparing the seed emulsion;

[0021] S006. After obtaining the seed emulsion, the initiator solution B and the remaining pre-emulsion were simultaneously added dropwise to the reactor for 230 to 250 min.

[0022] S007. After the initiator solution B and the pre-emulsion are added, the temperature in the reactor is maintained at 85°C to 87°C and kept warm for 60 to 65 minutes;

[0023] S008. After the insulation is completed, the temperature in the reactor is lowered to 50°C or below, and then a pH adjuster, 80 parts of deionized water, 25 parts of a cross-linking monomer and all the polyurethane curing agent are added to the reactor, and then the liquid in the reactor is stirred for 10 to 12 minutes; after the stirring is completed, it is naturally cooled, and the liquid in the reactor is filtered to obtain a polyurethane-modified acrylic emulsion.

[0024] Optionally, in step S002, the cross-linking monomer includes diacetone acrylamide; in step S008, the cross-linking monomer includes adipic acid dihydrazide.

[0025] The invention also provides a floor paint, comprising the polyurethane modified acrylic emulsion.

[0026] The beneficial effects of the present invention are as follows: the present invention provides a polyurethane modified acrylic emulsion, by providing a polyurethane curing agent for the emulsion, the acrylic emulsion and the isocyanate group in the polyurethane curing agent can undergo a cross-linking reaction to obtain a polyurethane modified acrylic emulsion, and the acrylic emulsion can take into account the characteristics of acrylic resin and polyurethane at the same time, thereby significantly providing the hardness and wear resistance, weather resistance and other capabilities of the emulsion paint film and the floor paint. By matching soft and hard monomers, the glass transition temperature of the polyurethane modified acrylic emulsion is between 30°C and 50°C. When the glass transition temperature of the emulsion is within the above range, the emulsion has strong rigidity, which can give the paint film higher hardness, wear resistance and other properties, while the acrylic emulsion itself has good weather resistance, and the strong rigidity of the emulsion can further enhance the ability of the emulsion paint film to resist erosion by the natural environment, thereby significantly improving the hardness, wear resistance, weather resistance and other properties of the floor paint containing the emulsion, and the floor paint has strong adhesion to the substrate.

[0027] The present invention also provides a method for preparing a polyurethane modified acrylic emulsion, which comprises preparing a seed emulsion first, then further polymerizing the seed emulsion, and strictly controlling the temperature in the reactor when the pH of the emulsion is adjusted, so that the prepared polyurethane modified acrylic emulsion has a narrow particle size distribution, is easy to control, and has good stability, thereby being able to help improve the mechanical properties and wear resistance, weather resistance, and the like of floor paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention provides a flow chart of a method for preparing a polyurethane-modified acrylic emulsion. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a polyurethane modified acrylic emulsion, comprising the following components in parts by weight:

[0031] 1470 parts of deionized water, 500-540 parts of methyl methacrylate, 220-260 parts of butyl acrylate, 100-200 parts of polyurethane curing agent, 78-82 parts of n-butyl methacrylate, 75 parts of cross-linking monomer, 57-62 parts of hydroxy acrylic monomer, 23-27 parts of acrylic acid, 18-23 parts of styrene, 10.3-12.3 parts of emulsifier, 12 parts of pH adjuster, 4-6 parts of adhesion promoter, and 4 parts of initiator.

[0032] In the composition of the above-mentioned polyurethane modified acrylic emulsion, styrene, methyl methacrylate, and n-butyl methacrylate are hard monomers, and the hard monomers can improve the hardness and wear resistance of the polyurethane modified acrylic emulsion after film formation, so that the wear resistance and hardness of the floor paint containing the polyurethane modified acrylic emulsion are improved. Butyl acrylate is a soft monomer, which can make the polyurethane modified acrylic emulsion have good film-forming properties, and can form a dense paint film on the surface of the substrate, thereby helping to improve the water resistance of the floor paint containing the polyurethane modified acrylic emulsion. The isocyanate group in the polyurethane curing agent can cross-link with the acrylic emulsion to obtain a polyurethane modified acrylic emulsion, so that the acrylic emulsion takes into account the characteristics of acrylic resin and the characteristics of polyurethane at the same time, thereby significantly providing the hardness and wear resistance, weather resistance and other capabilities of the emulsion paint film and the floor paint.

[0033] Acrylic acid and hydroxy acrylic acid monomers are functional monomers that can provide hydrogen bonds for the emulsion, so that hydrogen bonds are formed between the floor paint containing polyurethane modified acrylic emulsion and the substrate, thereby improving the adhesion of the floor paint to the substrate. In addition, the hydroxy acrylic acid monomer can also provide hydroxyl groups, which can cross-link with isocyanate groups, further promoting the cross-linking reaction between acrylic resin and isocyanate groups in the polyurethane curing agent, thereby improving the hardness, wear resistance, weather resistance and other properties of the emulsion paint film and floor paint.

[0034] The adhesion promoter can improve the wet adhesion of the latex paint film and floor paint to the substrate. The cross-linking monomer can give the latex paint film and floor paint good mechanical properties, making the floor paint firmly adhere to the surface of the substrate while also improving the wear resistance of the floor paint.

[0035] The glass transition temperature (Tg) of the polyurethane modified acrylic emulsion provided by the present invention is between 30°C and 50°C. When the glass transition temperature of the emulsion is within the above range, the emulsion has strong rigidity and can give the paint film high hardness, wear resistance and other properties. The acrylic emulsion itself has good weather resistance, and the strong rigidity of the emulsion can further enhance the ability of the emulsion paint film to resist erosion by the natural environment, thereby significantly improving the hardness, wear resistance, weather resistance and other properties of the floor paint containing the emulsion, and the floor paint has strong adhesion to the substrate.

[0036] Optionally, the polyurethane curing agent may be Covestro 2655 polyurethane curing agent.

[0037] Optionally, the cross-linking monomer includes at least one of diacetone acrylamide and adipic acid dihydrazide. Diacetone acrylamide is an amide cross-linking agent, and there are amide bonds and carbon-carbon double bonds in its molecular structure. The presence of carbon-carbon double bonds can make diacetone acrylamide copolymerize well into the emulsion macromolecular structure, thereby improving the stability of the emulsion macromolecules, and the adhesion of the floor paint containing polyurethane modified acrylic emulsion to the substrate can also be improved. Adipic acid dihydrazide is a hydrazide cross-linking agent, which undergoes a cross-linking reaction after the amide cross-linking agent is cross-linked with the acrylic polymer, which can further improve the cross-linking degree of the polymer and improve the adhesion of the floor paint to the substrate.

[0038] Optionally, the emulsifier includes at least one of sodium dodecyl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate. The above-mentioned emulsifier is a non-reactive emulsifier, which has a hydrophilic sulfate group, a sulfonic acid group and a hydrophobic alkyl group. This structure enables the non-reactive emulsifier to play a bridging role between the water phase and the oil phase, and can effectively reduce the tension of the oil-water interface. Therefore, the emulsification ability of the above-mentioned non-reactive emulsifier is relatively strong, which can improve the use stability and storage stability of the polyurethane modified acrylic emulsion, which is conducive to maintaining the quality of the floor paint and improving the construction efficiency of the floor paint.

[0039] Optionally, the pH adjuster includes at least one of ammonia water, sodium hydroxide and sodium bicarbonate.

[0040] Optionally, the adhesion promoter includes ethylene urea ethoxy methacrylate. The ethylene urea ethoxy methacrylate has a polyurea bond. After the polyurethane modified acrylic emulsion or the floor paint containing the emulsion is brushed on the surface of the substrate, the polyurea bond can bond with the hydrogen bond on the substrate, and after the polyurea bond and the hydrogen bond are bonded, the hydrogen bond is not easily destroyed by water molecules, so that good wet adhesion can be formed between the floor paint and the substrate, and even if the floor paint is exposed to the sun and rain, the floor paint is not easy to peel off.

[0041] Optionally, the initiator includes at least one of ammonium persulfate, potassium persulfate oxide, and sodium persulfate.

[0042] When the amount of polyurethane curing agent is too much, the use stability and storage stability of the polyurethane modified acrylic emulsion will be reduced, while when the amount of polyurethane curing agent is too little, the mechanical properties, wear resistance, weather resistance and other capabilities of the polyurethane modified acrylic emulsion paint film are not significantly improved. Preferably, the weight of the polyurethane curing agent accounts for 3% to 5% of the total weight of the polyurethane modified acrylic emulsion. The amount of polyurethane curing agent added can ensure that the modified acrylic emulsion has excellent mechanical properties, strong wear resistance, and can also be stored stably.

[0043] The present invention also provides a method for preparing the polyurethane modified acrylic emulsion, comprising the following steps:

[0044] S001. Add 0.3 parts of emulsifier and 1000 parts of deionized water to the reactor, stir and mix to obtain a base liquid;

[0045] S002. Add 10 to 12 parts of an emulsifier and 350 parts of deionized water to an emulsifying tank, stir and mix, then add styrene, methyl methacrylate, butyl acrylate, n-butyl methacrylate, hydroxy acrylic acid monomer, acrylic acid, an adhesion promoter and 50 parts of a cross-linking monomer, stir and mix to obtain a pre-emulsion;

[0046] S003. Add 1 part of the initiator and 10 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution A;

[0047] S004. Add 3 parts of initiator and 30 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution B;

[0048] S005. The temperature of the reactor was raised to 85 ℃ ~ 87 ℃, and the initiator solution A and the pre-emulsion were added to the reactor. The pre-emulsion was heated for 13 to 16 minutes and then the seed emulsion was prepared;

[0049] S006. After obtaining the seed emulsion, the initiator solution B and the remaining pre-emulsion were simultaneously added dropwise to the reactor for a time of 230 to 250 min;

[0050] S007. After the initiator solution B and the pre-emulsion are added, the temperature in the reactor is maintained at 85°C to 87°C and kept warm for 60 to 65 minutes;

[0051] S008. After the insulation is completed, the temperature in the reactor is lowered to 50°C or below, and then a pH adjuster, 80 parts of deionized water, 25 parts of a cross-linking monomer and all the polyurethane curing agent are added to the reactor, and then the liquid in the reactor is stirred for 10 to 12 minutes; after the stirring is completed, it is naturally cooled, and the liquid in the reactor is filtered to obtain a polyurethane-modified acrylic emulsion.

[0052] Wherein, in step S002, the cross-linking monomer includes diacetone acrylamide; in step S008, the cross-linking monomer includes adipic acid dihydrazide.

[0053] The preparation method of the polyurethane modified acrylic emulsion provided by the present invention is efficient and controllable. A seed emulsion is first prepared, and then further polymerization is performed on the basis of the seed emulsion, and the temperature in the reactor is strictly controlled when the pH value of the emulsion is adjusted, so that the prepared polyurethane modified acrylic emulsion has a narrow particle size distribution, is easy to control, and has good stability, thereby being helpful to improve the mechanical properties and wear resistance, weather resistance and other capabilities of floor paint.

[0054] The invention also provides a floor paint, comprising the polyurethane modified acrylic emulsion.

[0055] In order to further illustrate the polyurethane modified acrylic emulsion, preparation method and floor paint provided by the present invention, the following examples and comparative examples are provided.

[0056] Example 1

[0057] This embodiment provides a polyurethane modified acrylic emulsion, comprising the following components in parts by weight:

[0058] 1470 parts of deionized water, 530 parts of methyl methacrylate, 230 parts of butyl acrylate, 100 parts of polyurethane curing agent, 80 parts of n-butyl methacrylate, 50 parts of cross-linking monomer (diacetone acrylamide), 25 parts of cross-linking monomer (adipic acid dihydrazide), 60 parts of hydroxy acrylic acid monomer, 25 parts of acrylic acid, 20 parts of styrene, 12.3 parts of emulsifier (sodium lauryl polyoxyethylene ether sulfate), 12 parts of pH adjuster (ammonia water), 5 parts of adhesion promoter, and 4 parts of ammonium persulfate.

[0059] This embodiment also provides a method for preparing a polyurethane modified acrylic emulsion, comprising the following steps:

[0060] S001 was added to the reactor 0.3 parts of sodium lauryl polyoxyethylene ether sulfate and 1000 parts of deionized water, stirred and mixed to obtain a base liquid;

[0061] S002. Add 12 parts of sodium lauryl polyoxyethylene ether sulfate and 350 parts of deionized water to an emulsifying tank, stir and mix, then add styrene, methyl methacrylate, butyl acrylate, n-butyl methacrylate, hydroxy acrylic acid monomer, acrylic acid, adhesion promoter and 50 parts of diacetone acrylamide, stir and mix to obtain a pre-emulsion;

[0062] S003. Add 1 part of ammonium persulfate and 10 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution A;

[0063] S004. Add 3 parts of ammonium persulfate and 30 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution B;

[0064] S005. The temperature of the reactor was raised to 85 ℃ ~ 87 ℃, and the initiator solution A and the pre-emulsion were added to the reactor. The pre-emulsion was 5% by weight and kept warm for 15 min to obtain a seed emulsion;

[0065] S006. After obtaining the seed emulsion, the initiator solution B and the remaining pre-emulsion were simultaneously added dropwise to the reactor for 240 min.

[0066] S007. After the initiator solution B and the pre-emulsion are added, the temperature in the reactor is maintained at 85°C to 87°C and kept warm for 60 minutes;

[0067] S008. After the insulation is completed, the temperature in the reactor is lowered to 50°C, and then a pH adjuster, 80 parts of deionized water, 25 parts of adipic acid dihydrazide and all the polyurethane curing agent are added to the reactor, and then the liquid in the reactor is stirred for 10 minutes; after the stirring is completed, it is naturally cooled, and the liquid in the reactor is filtered to obtain a polyurethane-modified acrylic emulsion.

[0068] Example 2, Example 3 and Comparative Examples 1 to 3

[0069] The preparation methods of the polyurethane modified acrylic emulsions provided in Example 2, Example 3 and Comparative Examples 1 to 3 are the same as the preparation method provided in Example 1, except that the raw material compositions of the polyurethane modified acrylic emulsions are not completely the same, as shown in Table 1 below.

[0070] Table 1:

[0071]

[0072] Wherein, the glass transition temperature of the polyurethane modified acrylic emulsion provided in Example 1 is 39°C;

[0073] The glass transition temperature of the polyurethane-modified acrylic emulsion provided in Example 2 is 45°C;

[0074] The glass transition temperature of the polyurethane-modified acrylic emulsion provided in Example 3 is 33°C;

[0075] The glass transition temperature of the polyurethane modified acrylic emulsion provided in Comparative Example 1 is 21°C;

[0076] The glass transition temperature of the polyurethane modified acrylic emulsion provided in Comparative Example 2 is 55°C;

[0077] The glass transition temperature of the polyurethane modified acrylic emulsion provided in Comparative Example 3 is 39°C.

[0078] The polyurethane modified acrylic emulsions prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are used to prepare floor paint. The floor paint includes the following components in parts by weight:

[0079] 80 parts of polyurethane modified acrylic emulsion, 15 parts of water, 6 parts of alcohol ester film-forming agent, 0.5 parts of wetting agent, 0.2 parts of leveling agent, 0.2 parts of N,N-dimethylethanolamine, and 0.1 parts of BYK-024.

[0080] The film hardness of the floor paint configured above was tested in accordance with the provisions of the standard "GB / T 6739-2006 Paint and varnish pencil method for determination of film hardness"; the adhesion of the floor paint configured above was tested in accordance with the provisions of the standard "GB / T 9286-2021 Paint and varnish scratch test"; the tensile strength, water immersion tensile strength, weather resistance, water resistance, impact resistance, acid resistance and alkali resistance of the floor paint configured above were tested in accordance with the provisions of the standard "GB / T22374-2018 Floor paint coating materials": the wear resistance of the floor paint configured above was tested in accordance with the "GB / T 1768-2006 Determination of wear resistance of paints and varnishes - rotating rubber grinding wheel method", and the test results are shown in Table 2 below.

[0081] Table 2:

[0082]

[0083] From the test results of Table 2, it can be seen that the floor paint configured with the polyurethane modified acrylic emulsion provided in Comparative Example 1 has poor wear resistance (in Table 2, the larger the wear resistance value, the worse the wear resistance of the coating film), and the weather resistance is not passed. This is because the glass transition temperature of the polyurethane modified acrylic emulsion provided in Comparative Example 1 is low (tg is 21°C), and the rigidity of the emulsion is not strong, resulting in the emulsion paint film being not wear-resistant and having poor weather resistance. The floor paint configured with the polyurethane modified acrylic emulsion provided in Comparative Example 2 has cracks on the surface of the coating film after curing, and the coating film has poor adhesion to the substrate. This is because the rigidity of the polyurethane modified acrylic emulsion provided in Comparative Example 2 is too strong, resulting in the paint film having a certain brittleness and easy cracking. The mechanical properties (impact resistance) and wear resistance of the floor paint configured with the polyurethane modified acrylic emulsion provided in Comparative Example 3 are not as good as those using Examples 1 to 3. This is because the amount of polyurethane curing agent in the polyurethane modified acrylic emulsion provided in Comparative Example 3 is too small, so that the mechanical properties and wear resistance of the modified acrylic emulsion are not significantly improved.

[0084] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A polyurethane modified acrylic emulsion, characterized in that: The composition comprises the following parts by weight: 1470 parts of deionized water, 500-540 parts of methyl methacrylate, 220-260 parts of butyl acrylate, 100-200 parts of polyurethane curing agent, 78-82 parts of n-butyl methacrylate, 75 parts of cross-linking monomer, 57-62 parts of hydroxy acrylic monomer, 23-27 parts of acrylic acid, 18-23 parts of styrene, 10.3-12.3 parts of emulsifier, 12 parts of pH adjuster, 4-6 parts of adhesion promoter, and 4 parts of initiator.

2. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The cross-linking monomer includes at least one of diacetone acrylamide and adipic acid dihydrazide.

3. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The emulsifier includes at least one of sodium dodecyl polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

4. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The pH adjuster includes at least one of ammonia water, sodium hydroxide and sodium bicarbonate.

5. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The adhesion promoter includes ethylene urea ethoxy methacrylate.

6. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The initiator includes at least one of ammonium persulfate, potassium persulfate oxide, and sodium persulfate.

7. The polyurethane modified acrylic emulsion according to claim 1, characterized in that: The weight of the polyurethane curing agent accounts for 3% to 5% of the total weight of the polyurethane modified acrylic emulsion.

8. A method for preparing the polyurethane modified acrylic emulsion according to any one of claims 1 to 7, characterized in that: The following steps are involved: S001. Add 0.3 parts of emulsifier and 1000 parts of deionized water to the reactor, stir and mix to obtain a base liquid; S002. Add 10 to 12 parts of an emulsifier and 350 parts of deionized water to an emulsifying tank, stir and mix, then add styrene, methyl methacrylate, butyl acrylate, n-butyl methacrylate, hydroxy acrylic acid monomer, acrylic acid, an adhesion promoter and 50 parts of a cross-linking monomer, stir and mix to obtain a pre-emulsion; S003. Add 1 part of the initiator and 10 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution A; S004. Add 3 parts of initiator and 30 parts of deionized water to the initiator tank, stir and mix to obtain an initiator solution B; S005. The temperature of the reactor was raised to 85 ℃ ~ 87 ℃, and the initiator solution A and the pre-emulsion were added to the reactor. The pre-emulsion was heated for 13 to 16 minutes to obtain a seed emulsion; S006. After obtaining the seed emulsion, the initiator solution B and the remaining pre-emulsion were simultaneously added dropwise to the reactor for a time of 230 to 250 min; S007. After the initiator solution B and the pre-emulsion are added, the temperature in the reactor is maintained at 85°C to 87°C and kept warm for 60 to 65 minutes; S008. After the insulation is completed, the temperature in the reactor is lowered to 50°C or below, and then a pH adjuster, 80 parts of deionized water, 25 parts of a cross-linking monomer and all the polyurethane curing agent are added to the reactor, and then the liquid in the reactor is stirred for 10 to 12 minutes; after the stirring is completed, it is naturally cooled, and the liquid in the reactor is filtered to obtain a polyurethane-modified acrylic emulsion.

9. The method for preparing the polyurethane modified acrylic emulsion according to claim 8, characterized in that: In step S002, the cross-linking monomer includes diacetone acrylamide; in step S008, the cross-linking monomer includes adipic acid dihydrazide.

10. A floor paint, characterized in that: The invention comprises the polyurethane modified acrylic emulsion according to any one of claims 1 to 7.

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