Preparation method of stain-resistant and wiping-resistant water-based UV matte coating

Abstract

The invention relates to the technical field of preparation of UV coatings, and discloses a preparation method of a stain-resistant and wiping-resistant water-based UV matte coating. The preparation method comprises the following steps: S1, mixing talcum powder, barium sulfate, aluminum hydroxide and quartz powder to obtain the extinction powder. S2, mixing deionized water, dodecyl sulfate, waterborne polyurethane resin and an active monomer to obtain an emulsion; s3, potassium persulfate is taken and diluted with deionized water, and an initiation solution is obtained. And S4, polymerizing the emulsion and the initiation liquid to obtain latex A. S5, adding nano titanium dioxide, matting powder, a photoinitiator, a coalescing agent and triethanolamine into the latex, and mixing to obtain latex B; and S6, at normal temperature, taking a small amount of latex B for multiple times, and grinding to obtain the UV matte coating. The prepared UV matte coating has the advantages of being good in anti-settling property, good in permeability after curing, good in covering power and resistant to wear, shearing force is applied to the coating based on wet grinding, and the adverse effect of introduction of a flatting agent on the photocuring performance of the coating is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of UV coating preparation, in particular to a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, and also to a UV matte coating prepared by the preparation method. Background Art

[0002] Water-based UV coatings do not require the addition of curing agents, diluents and other solvents, which greatly reduces the emission of volatile organic compounds. They are environmentally friendly and have excellent environmental protection properties. In addition, the matte coating formed by curing water-based UV coatings has a surface that is not visible to the naked eye. The surface is diffusely reflected, without glare, not dazzling, and has a strong texture. Therefore, it is widely used in industrial production such as wood flooring, furniture and the automotive industry.

[0003] For example, documents such as CN202411128754.5 and CN202110287390.5, in order to improve the leveling properties of the coating, silicone materials are added during the preparation process. However, coatings containing silicone will have poor curing conditions such as oil floating and inconvenience in recoating after light curing, which reduces the curing quality of UV coatings. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating to prepare a UV coating with good anti-settling properties, uniform powder dispersion and good curing quality.

[0005] A method for preparing a stain-resistant and wipe-resistant water-based UV matte coating comprises the following steps:

[0006] S1: Mix talcum powder, barium sulfate, aluminum hydroxide and quartz powder, sieve to obtain matting powder, and set aside;

[0007] S2 takes deionized water, dodecyl sulfuric acid, waterborne polyurethane resin and active monomer and mixes them to obtain an emulsion;

[0008] S3: Take potassium persulfate and dilute it with deionized water to obtain an initiating solution;

[0009] S4 takes the emulsion and the initiating liquid for polymerization reaction to obtain latex A;

[0010] S5. Add nano titanium dioxide, matting powder, photoinitiator, film-forming aid and triethanolamine to the latex, stir and mix to obtain latex B;

[0011] S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

[0012] As a further improvement of the above scheme, the preparation method of the matting powder is specifically performed as follows:

[0013] S11: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5-2.5:0.5-1:0.2-0.8:0.5-1.5 to obtain a mixed powder;

[0014] S12 grinds the mixed powder, and then passes it through a 6000 mesh screen to obtain a matting powder. The matting powder of the present invention is a quaternary mixed system of talcum powder-barium sulfate-aluminum hydroxide-quartz powder, based on the synergistic matting and permeability of talcum powder, which plays a role of anti-settling synergistic effect, based on the synergistic matting of barium sulfate, and gives the coating a good hiding power, based on the synergistic matting of aluminum hydroxide, giving fire retardant properties, and the prepared coating has good anti-settling property, good permeability after curing, good hiding power and whitening effect, based on the synergistic matting of quartz powder, and gives the coating good wear resistance.

[0015] As a further improvement of the above solution, the grinding process is carried out in a planetary ball mill, and the ball milling speed is 600-900 r / min.

[0016] As a further improvement of the above scheme, the preparation method of the emulsion is specifically performed as follows:

[0017] S21 Add deionized water and dodecyl sulfuric acid into the emulsifying kettle, and stir and mix at 200-400 r / min for 15-25 min;

[0018] S22 continues to add waterborne polyurethane resin and active monomer, and stir and mix for 20 minutes to obtain an emulsion. In the present invention, waterborne polyurethane resin is added, and the hydrophilic groups in the waterborne polyurethane resin are used to form hydrogen bonds with water molecules to increase the solubility and stability of the polymer in water. The waterborne polyurethane resin can form a dense coating structure during the film-forming process, reducing the possibility of water penetration and diffusion. The hydrophobic groups in the molecular structure can also enhance the water resistance of the coating. In the present invention, sodium dodecyl sulfate is added as an emulsifier to reduce interfacial tension, so that the monomers are dispersed to form fine droplets, so that the mixed solution forms a stable emulsified system.

[0019] As a further improvement of the above scheme, the active monomer is any one of styrene, butadiene, acrylic acid and unsaturated carboxylic acid. The present invention uses environmentally friendly waterborne polyurethane resin as a polymerization monomer and uses deionized water as a dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having little odor. It provides a flexible segment and undergoes free radical copolymerization with the active monomer to form a three-dimensional network structure, which can significantly improve the water resistance and mechanical strength of the cured film of the coating.

[0020] As a further improvement of the above solution, the mass volume ratio of potassium persulfate to deionized water is 1: 10. In the present invention, potassium persulfate is added to initiate the copolymerization reaction between the waterborne polyurethane resin and the active monomer.

[0021] As a further improvement of the above scheme, the method for obtaining latex by polymerization reaction is specifically operated as follows: first add 20% of emulsion and 25% of initiating liquid, keep warm for reaction for 30 minutes, then drop the remaining emulsion and initiating liquid, keep warm for reaction for 2 hours, and obtain latex; during the process of dropping the remaining emulsion and the remaining initiating liquid, the reaction temperature is 80-86° C., the dropping time is 3-4 hours, and the insulation temperature is 86-88° C. In the present invention, the purpose of adding 20% ​​of emulsion and 25% of initiating liquid for reaction is to pre-react for a period of time first, so that the emulsion and initiator added later can react more fully, thereby improving the conversion efficiency of latex.

[0022] As a further improvement of the above scheme, tetrabutyl titanate and anhydrous ethanol are used to prepare the nano titanium dioxide, and the specific operation is as follows:

[0023] Step 1: Tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A; deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B;

[0024] Step 2: Add solution A dropwise into solution B at room temperature while stirring, so that solution A and solution B are hydrolyzed and polycondensed to form a light yellow transparent sol;

[0025] Step 3: Dry the sol in a drying oven at 80°C for 24 hours to form a gel, place the gel in a high-temperature furnace and heat it to 500°C for heat treatment, and keep it warm for 2 hours to obtain nano titanium dioxide powder. The present invention adds nano titanium dioxide, which can stimulate electron transition under ultraviolet light irradiation to form electron-hole pairs with strong redox ability, so that it can react with water molecules and oxygen molecules to generate hydroxyl radicals and superoxide anion radicals with strong oxidizing properties, thereby degrading organic pollutants on the coating to keep the coating surface clean, and the photocatalytic effect of nano titanium dioxide can cause photodegradation of organic matter, giving the coating anti-fouling and self-cleaning properties, and also improving the ultraviolet protection performance of the coating, so as to better meet the protection needs in harsh environments.

[0026] As a further improvement of the above scheme, the film-forming aid is at least one of ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether and propylene glycol butyl ether. In the present invention, the film-forming aid is added to promote the plastic flow and elastic deformation of particles in the emulsion, improve its aggregation performance, avoid agglomeration and promote coating film formation.

[0027] As a further improvement of the above scheme, the photoinitiator is any one of diaryliodonium salt I-250, α-aminoalkylphenone, methyl benzoylformate and 2-hydroxy-2-methyl-1-phenylpropanone. In the present invention, the photoinitiator is added so that the coating absorbs energy of a certain wavelength in the ultraviolet light region or the visible light region to generate free radicals, cations, etc., thereby initiating monomer polymerization, cross-linking and curing.

[0028] As a further improvement of the above scheme, the UV matte coating prepared by the preparation method has the following composition by weight: 30 to 60 parts of waterborne polyurethane resin, 20 to 40 parts of active monomer, 1 to 4 parts of sodium dodecyl sulfate, 2 to 6 parts of potassium persulfate, 10 to 18 parts of matting powder, 7 to 12 parts of nano titanium dioxide, 1 to 5 parts of triethanolamine, 0.5 to 2 parts of photoinitiator, 3 to 6 parts of film-forming aid, and 50 to 80 parts of deionized water.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The matting powder used in the present invention is a quaternary mixed system of talcum powder, barium sulfate, aluminum hydroxide and quartz powder, which, on the one hand, acts as a filler to thicken the coating, and on the other hand, acts as a matting agent based on the diffuse reflection principle of the powder, thereby obtaining the effect of a matte coating. Based on the synergistic coordination of the quaternary system, the performance of the coating is optimized, so that the prepared UV matte coating has the advantages of good anti-settling property, good permeability after curing, good covering power and wear resistance.

[0031] The present invention adopts a wet grinding method to make the powder in the prepared UV matte paint evenly dispersed, avoiding the problem that the paint is delaminated and the powder floats on the surface after curing, which affects the quality of the coating formed by the curing of the paint. At the same time, based on the wet grinding, a shear force is applied to the paint, and an external force acts on the paint to spread it into a film, giving the paint good flow and leveling properties, without the need for a leveling agent, such as silicone, wax slurry, etc., overcoming the adverse effect of the leveling agent on the light curing performance of the paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a flow chart of a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating provided by the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Additional aspects and advantages of the present invention will be given in part in the following description, and will become apparent from the following description, or will be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0034] The specific embodiments of the present invention are described in detail below.

[0035] Example 1

[0036] This embodiment provides a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, which comprises the following steps:

[0037] S1: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5:0.5:0.2:0.5 to obtain a mixed powder, and the mixed powder is ground and then passed through a 6000 mesh sieve to obtain a matte powder. The grinding process is carried out in a planetary ball mill, and the ball mill speed is 800r / min.

[0038] S2: Add deionized water and 1 part of dodecyl sulfuric acid into the emulsification kettle, stir and mix at 300 r / min for 25 minutes, continue to add 30 parts of waterborne polyurethane resin and 20 parts of styrene, stir and mix for 20 minutes to obtain an emulsion.

[0039] In this embodiment, sodium dodecyl sulfate is added as an emulsifier to reduce interfacial tension, so that the monomer is dispersed to form fine droplets, so that the mixed solution forms a stable emulsified system. The addition of waterborne polyurethane resin uses the hydrophilic groups in the waterborne polyurethane resin to form hydrogen bonds with water molecules, thereby increasing the solubility and stability of the polymer in water. The waterborne polyurethane resin can form a dense coating structure during the film formation process, reducing the possibility of water penetration and diffusion, and the hydrophobic groups in the molecular structure can also enhance the water resistance of the coating.

[0040] In this embodiment, an environmentally friendly water-based polyurethane resin is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The water-based polyurethane resin has the advantages of being non-flammable and having a low odor. It provides a flexible chain segment and undergoes a free radical copolymerization reaction with styrene to form a three-dimensional network structure, which can significantly improve the water resistance and mechanical strength of the cured film of the coating.

[0041] S3: taking 2 parts of potassium persulfate and diluting them with deionized water to obtain an initiating solution, wherein the mass volume ratio of the potassium persulfate to the deionized water is 1:10. In this embodiment, potassium persulfate is added to initiate the copolymerization reaction between the waterborne polyurethane resin and styrene.

[0042] S4 firstly adds 20% of the emulsion and 25% of the initiating liquid, and keeps the temperature for reaction for 30 minutes, then drips the remaining emulsion and the initiating liquid, and keeps the temperature for reaction for 2 hours to obtain latex. During the dripping of the remaining emulsion and the remaining initiating liquid, the reaction temperature is 82° C., the dripping time is 3 hours, and the insulation temperature is 86° C. In this embodiment, the purpose of first adding 20% ​​of the emulsion and 25% of the initiating liquid for reaction is to pre-react for a period of time first, so that the emulsion and the initiator added later can react more fully, thereby improving the conversion efficiency of the latex.

[0043] S5: adding 7 parts of nano titanium dioxide, 10 parts of matting powder, 0.5 parts of diaryliodonium salt I-250, 3 parts of ethylene glycol butyl ether and 1 part of triethanolamine to the latex, stirring and mixing to obtain latex B;

[0044] Matt powder is added during the preparation process of this embodiment. On the one hand, it acts as a filler to thicken the coating. On the other hand, it acts as a matte based on the diffuse reflection principle of the powder, thereby obtaining a matte coating effect.

[0045] The nano titanium dioxide is prepared by using tetrabutyl titanate and anhydrous ethanol. The specific operation is as follows: tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A, deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B. Solution A is added dropwise to solution B while stirring at room temperature, and solution A and solution B are hydrolyzed and condensed to form a light yellow transparent sol. The sol is dried in a drying oven at 80°C for 24 hours to form a gel, and the gel is placed in a high-temperature furnace and heated to 500°C for heat treatment, and kept warm for 2 hours to obtain nano titanium dioxide powder.

[0046] In this embodiment, ethylene glycol butyl ether is added to promote the plastic flow and elastic deformation of particles in the emulsion, improve its aggregation performance, avoid agglomeration and promote coating film formation. Diaryliodonium salt I-250 is added to make the coating absorb energy of a certain wavelength in the ultraviolet light region or visible light region to generate free radicals, cations, etc., and then initiate monomer polymerization and cross-linking curing. Triethanolamine is added as a neutralizing liquid to make the storage stability of the aqueous dispersion in latex B good and improve the light curing activity of the coating.

[0047] S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

[0048] The UV matte coating prepared by the preparation method of this embodiment has the following composition by weight: 30 parts of waterborne polyurethane resin, 20 parts of styrene, 1 part of sodium dodecyl sulfate, 2 parts of potassium persulfate, 10 parts of matting powder, 7 parts of nano titanium dioxide, 1 part of triethanolamine, 0.5 parts of diaryliodonium salt I-2500, 3 parts of ethylene glycol butyl ether, and 50 parts of deionized water.

[0049] Example 2

[0050] This embodiment provides a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, which comprises the following steps:

[0051] S1: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5:0.5:0.2:0.5 to obtain a mixed powder, and the mixed powder is ground and then passed through a 6000 mesh sieve to obtain a matte powder. The grinding process is carried out in a planetary ball mill, and the ball mill speed is 800r / min.

[0052] S2 adds deionized water and 2 parts of dodecyl sulfuric acid to the emulsifying kettle, stirs and mixes for 25 minutes at 300r / min, continues to add 40 parts of waterborne polyurethane resin and 25 parts of butadiene, stirs and mixes for 20 minutes, and obtains an emulsion. In this embodiment, sodium lauryl sulfate is added as an emulsifier to reduce the interfacial tension, so that the monomer is dispersed to form fine droplets, so that the mixed solution forms a stable emulsified system. Adding waterborne polyurethane resin, the hydrophilic groups in the waterborne polyurethane resin are used to form hydrogen bonds with water molecules, increase the solubility and stability of the polymer in water, and the waterborne polyurethane resin can form a dense coating structure during the film forming process, reduce the possibility of water penetration and diffusion, and the hydrophobic groups in the molecular structure can also enhance the water resistance of the coating.

[0053] In this embodiment, an environmentally friendly water-based polyurethane resin is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The water-based polyurethane resin has the advantages of being non-flammable and having a low odor. It provides a flexible chain segment and undergoes a free radical copolymerization reaction with butadiene to form a three-dimensional network structure, which can significantly improve the water resistance and mechanical strength of the cured film of the coating.

[0054] S3: 3 parts of potassium persulfate are diluted with deionized water to obtain an initiating solution, wherein the mass volume ratio of the potassium persulfate to the deionized water is 1: 10. In this embodiment, potassium persulfate is added to initiate the copolymerization reaction between the waterborne polyurethane resin and butadiene.

[0055] S4 firstly adds 20% of the emulsion and 25% of the initiating liquid, and keeps the temperature for reaction for 30 minutes, then drips the remaining emulsion and the initiating liquid, and keeps the temperature for reaction for 2 hours to obtain latex. During the dripping of the remaining emulsion and the remaining initiating liquid, the reaction temperature is 82° C., the dripping time is 3 hours, and the insulation temperature is 86° C. In this embodiment, the purpose of first adding 20% ​​of the emulsion and 25% of the initiating liquid for reaction is to pre-react for a period of time first, so that the emulsion and the initiator added later can react more fully, thereby improving the conversion efficiency of the latex.

[0056] S5. Add 8 parts of nano titanium dioxide, 12 parts of matting powder, 1 part of α-aminoalkylphenone, 4 parts of diethylene glycol butyl ether and 3 parts of triethanolamine to the latex, stir and mix to obtain latex B;

[0057] Matt powder is added during the preparation process of this embodiment. On the one hand, it acts as a filler to thicken the coating. On the other hand, it acts as a matte based on the diffuse reflection principle of the powder, thereby obtaining a matte coating effect.

[0058] The nano titanium dioxide is prepared by using tetrabutyl titanate and anhydrous ethanol. The specific operation is as follows: tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A, deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B. Solution A is added dropwise to solution B while stirring at room temperature, and solution A and solution B are hydrolyzed and condensed to form a light yellow transparent sol. The sol is dried in a drying oven at 80°C for 24 hours to form a gel, and the gel is placed in a high-temperature furnace and heated to 500°C for heat treatment, and kept warm for 2 hours to obtain nano titanium dioxide powder.

[0059] In this embodiment, diethylene glycol butyl ether is added to promote the plastic flow and elastic deformation of particles in the emulsion, improve its aggregation performance, avoid agglomeration and promote the film formation of the coating. α-amino alkyl phenone is added to make the coating absorb energy of a certain wavelength in the ultraviolet light region or the visible light region to generate free radicals, cations, etc., and then initiate monomer polymerization and cross-linking curing. Triethanolamine is added as a neutralizing liquid to improve the storage stability of the aqueous dispersion in latex B and improve the light curing activity of the coating.

[0060] S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

[0061] The UV matte coating prepared by the preparation method of this embodiment has the following composition by weight: 40 parts of waterborne polyurethane resin, 25 parts of butadiene, 2 parts of sodium lauryl sulfate, 3 parts of potassium persulfate, 12 parts of matting powder, 8 parts of nano titanium dioxide, 3 parts of triethanolamine, 1 part of α-aminoalkyl phenone, 4 parts of diethylene glycol butyl ether, and 60 parts of deionized water.

[0062] Example 3

[0063] This embodiment provides a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, which comprises the following steps:

[0064] S1: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5:0.5:0.2:0.5 to obtain a mixed powder, and the mixed powder is ground and then passed through a 6000 mesh sieve to obtain a matte powder. The grinding process is carried out in a planetary ball mill, and the ball mill speed is 800r / min.

[0065] S2: Deionized water and 3 parts of dodecyl sulfuric acid were added to the emulsification kettle, and the mixture was stirred at 300 r / min for 25 minutes. Then, 50 parts of waterborne polyurethane resin and 35 parts of acrylic acid were added, and the mixture was stirred for 20 minutes to obtain an emulsion.

[0066] In this embodiment, sodium dodecyl sulfate is added as an emulsifier to reduce interfacial tension, so that the monomer is dispersed to form fine droplets, so that the mixed solution forms a stable emulsified system. The addition of waterborne polyurethane resin uses the hydrophilic groups in the waterborne polyurethane resin to form hydrogen bonds with water molecules, thereby increasing the solubility and stability of the polymer in water. The waterborne polyurethane resin can form a dense coating structure during the film formation process, reducing the possibility of water penetration and diffusion, and the hydrophobic groups in the molecular structure can also enhance the water resistance of the coating.

[0067] In this embodiment, an environmentally friendly water-based polyurethane resin is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The water-based polyurethane resin has the advantages of being non-flammable and having a low odor. It provides a flexible chain segment and undergoes a free radical copolymerization reaction with acrylic acid to form a three-dimensional network structure, which can significantly improve the water resistance and mechanical strength of the cured film of the coating.

[0068] S3: Take 4 parts of potassium persulfate and dilute them with deionized water to obtain an initiating solution, wherein the mass volume ratio of the potassium persulfate to the deionized water is 1: 10. In this embodiment, potassium persulfate is added to initiate the copolymerization reaction between the waterborne polyurethane resin and the acrylic acid.

[0069] S4 firstly adds 20% of the emulsion and 25% of the initiating liquid, and keeps the temperature for reaction for 30 minutes, then drips the remaining emulsion and the initiating liquid, and keeps the temperature for reaction for 2 hours to obtain latex. During the dripping of the remaining emulsion and the remaining initiating liquid, the reaction temperature is 82° C., the dripping time is 3 hours, and the insulation temperature is 86° C. In this embodiment, the purpose of first adding 20% ​​of the emulsion and 25% of the initiating liquid for reaction is to pre-react for a period of time first, so that the emulsion and the initiator added later can react more fully, thereby improving the conversion efficiency of the latex.

[0070] S5. Add 10 parts of nano titanium dioxide, 16 parts of matting powder, 1.5 parts of methyl benzoylformate, 5 parts of propylene glycol methyl ether and 4 parts of triethanolamine to the latex, stir and mix to obtain latex B;

[0071] Matt powder is added during the preparation process of this embodiment. On the one hand, it acts as a filler to thicken the coating. On the other hand, it acts as a matte based on the diffuse reflection principle of the powder, thereby obtaining a matte coating effect.

[0072] The nano titanium dioxide is prepared by using tetrabutyl titanate and anhydrous ethanol. The specific operation is as follows: tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A, deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B. Solution A is added dropwise to solution B while stirring at room temperature, and solution A and solution B are hydrolyzed and condensed to form a light yellow transparent sol. The sol is dried in a drying oven at 80°C for 24 hours to form a gel, and the gel is placed in a high-temperature furnace and heated to 500°C for heat treatment, and kept warm for 2 hours to obtain nano titanium dioxide powder.

[0073] In this embodiment, propylene glycol methyl ether is added to promote the plastic flow and elastic deformation of particles in the emulsion, improve its aggregation performance, avoid agglomeration and promote coating film formation. Methyl benzoylformate is added to make the coating absorb energy of a certain wavelength in the ultraviolet light region or the visible light region to generate free radicals, cations, etc., and then initiate monomer polymerization and cross-linking curing. Triethanolamine is added as a neutralizing liquid to make the storage stability of the aqueous dispersion in latex B good and improve the light curing activity of the coating.

[0074] S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

[0075] The UV matte coating prepared by the preparation method of this embodiment has the following composition in parts by weight: 50 parts of waterborne polyurethane resin, 35 parts of acrylic acid, 3 parts of sodium lauryl sulfate, 4 parts of potassium persulfate, 16 parts of matting powder, 10 parts of nano titanium dioxide, 4 parts of triethanolamine, 1.5 parts of methyl benzoylformate, 5 parts of propylene glycol methyl ether, and 75 parts of deionized water.

[0076] Example 4

[0077] This embodiment provides a method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, which comprises the following steps:

[0078] S1: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5:0.5:0.2:0.5 to obtain a mixed powder, and the mixed powder is ground and then passed through a 6000 mesh sieve to obtain a matte powder. The grinding process is carried out in a planetary ball mill, and the ball mill speed is 800r / min.

[0079] S2: Deionized water and 4 parts of dodecyl sulfuric acid were added to the emulsification kettle, and the mixture was stirred at 300 r / min for 25 minutes. Then, 60 parts of waterborne polyurethane resin and 40 parts of unsaturated carboxylic acid were added, and the mixture was stirred for 20 minutes to obtain an emulsion.

[0080] In this embodiment, sodium dodecyl sulfate is added as an emulsifier to reduce interfacial tension, so that the monomer is dispersed to form fine droplets, so that the mixed solution forms a stable emulsified system. The addition of waterborne polyurethane resin uses the hydrophilic groups in the waterborne polyurethane resin to form hydrogen bonds with water molecules, thereby increasing the solubility and stability of the polymer in water. The waterborne polyurethane resin can form a dense coating structure during the film formation process, reducing the possibility of water penetration and diffusion, and the hydrophobic groups in the molecular structure can also enhance the water resistance of the coating.

[0081] In this embodiment, an environmentally friendly water-based polyurethane resin is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The water-based polyurethane resin has the advantages of being non-flammable and having a low odor. It provides a flexible chain segment and undergoes a free radical copolymerization reaction with an unsaturated carboxylic acid to form a three-dimensional network structure, which can significantly improve the water resistance and mechanical strength of the cured film of the coating.

[0082] S3: 6 parts of potassium persulfate are diluted with deionized water to obtain an initiating solution, wherein the mass volume ratio of potassium persulfate to deionized water is 1: 10. In this embodiment, potassium persulfate is added to initiate the copolymerization reaction between the waterborne polyurethane resin and the unsaturated carboxylic acid.

[0083] S4 firstly adds 20% of the emulsion and 25% of the initiating liquid, and keeps the temperature for reaction for 30 minutes, then drips the remaining emulsion and the initiating liquid, and keeps the temperature for reaction for 2 hours to obtain latex. During the dripping of the remaining emulsion and the remaining initiating liquid, the reaction temperature is 82° C., the dripping time is 3 hours, and the insulation temperature is 86° C. In this embodiment, the purpose of first adding 20% ​​of the emulsion and 25% of the initiating liquid for reaction is to pre-react for a period of time first, so that the emulsion and the initiator added later can react more fully, thereby improving the conversion efficiency of the latex.

[0084] S5. Add 12 parts of nano titanium dioxide, 18 parts of matting powder, 2 parts of 2-hydroxy-2-methyl-1-phenylacetone, 6 parts of propylene glycol butyl ether and 5 parts of triethanolamine to the latex, stir and mix, and obtain latex B;

[0085] Matt powder is added during the preparation process of this embodiment. On the one hand, it acts as a filler to thicken the coating. On the other hand, it acts as a matte based on the diffuse reflection principle of the powder, thereby obtaining a matte coating effect.

[0086] The nano titanium dioxide is prepared by using tetrabutyl titanate and anhydrous ethanol. The specific operation is as follows: tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A, deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B. Solution A is added dropwise to solution B while stirring at room temperature, and solution A and solution B are hydrolyzed and condensed to form a light yellow transparent sol. The sol is dried in a drying oven at 80°C for 24 hours to form a gel, and the gel is placed in a high-temperature furnace and heated to 500°C for heat treatment, and kept warm for 2 hours to obtain nano titanium dioxide powder.

[0087] In this embodiment, propylene glycol butyl ether is added to promote the plastic flow and elastic deformation of particles in the emulsion, improve its aggregation performance, avoid agglomeration and promote coating film formation. 2-Hydroxy-2-methyl-1-phenylacetone is added to make the coating absorb energy of a certain wavelength in the ultraviolet light region or the visible light region to generate free radicals, cations, etc., and then initiate monomer polymerization and cross-linking curing. Triethanolamine is added as a neutralizing liquid to improve the storage stability of the aqueous dispersion in latex B and improve the light curing activity of the coating.

[0088] S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

[0089] The UV matte coating prepared by the preparation method of this embodiment has the following composition by weight: 60 parts of waterborne polyurethane resin, 40 parts of unsaturated carboxylic acid, 4 parts of sodium lauryl sulfate, 6 parts of potassium persulfate, 18 parts of matting powder, 12 parts of nano titanium dioxide, 5 parts of triethanolamine, 2 parts of 2-hydroxy-2-methyl-1-phenylacetone, 6 parts of propylene glycol butyl ether, and 80 parts of deionized water.

[0090] The following commercially available UV matte coating is used as a comparative example, and the water resistance (GB / T1733-1993) of the UV matte coating of Examples 1-4 is tested. The specific test process is not repeated here, and the test results are as follows: the UV matte coating of the comparative example, the coating formed by light-assisted curing is impermeable for 2 hours, and the UV matte coating of Examples 1-4, the coating formed by light-assisted curing is impermeable for more than 4 hours.

[0091] The test results of the stain resistance test are as follows: the coating formed by the UV matte paint of the comparative example is evaluated as level 3-4 in appearance after cleaning, the coating formed by the UV matte paint of Example 1 is evaluated as level 1-2 in appearance after cleaning, the coating formed by the UV matte paint of Example 2 is evaluated as level 1-2 in appearance after cleaning, the coating formed by the UV matte paint of Example 3 is evaluated as level 1-2 in appearance after cleaning, and the coating formed by the UV matte paint of Example 4 is evaluated as level 2-3 in appearance after cleaning. Level 0 means that the appearance of the coating after cleaning is consistent with that of the uncontaminated coating, and level 5 means that the appearance of the coating has changed seriously.

[0092] The results of the wipe resistance test are as follows: the coating of the comparative example is resistant to 1560 wipings with acetone, the coating of Example 1 is resistant to 2300 wipings with acetone, the coating of Example 2 is resistant to 2360 wipings with acetone, the coating of Example 3 is resistant to 2570 wipings with acetone, and the coating of Example 4 is resistant to 2400 wipings with acetone. The above results prove that the UV matte coating prepared by the preparation method of the present invention has significantly improved stain resistance, wipe resistance and water resistance.

[0093] The above embodiments are merely preferred implementations of the present invention. Any simple modification, amendment and substitution of the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a stain-resistant and wipe-resistant water-based UV matte coating, characterized in that: The following steps are involved: S1: Mix talcum powder, barium sulfate, aluminum hydroxide and quartz powder, sieve to obtain matting powder, and set aside; S2 takes deionized water, dodecyl sulfuric acid, waterborne polyurethane resin and active monomer and mixes them to obtain an emulsion; S3: Take potassium persulfate and dilute it with deionized water to obtain an initiating solution; S4 takes the emulsion and the initiating liquid for polymerization reaction to obtain latex A; S5. Add nano titanium dioxide, matting powder, photoinitiator, film-forming aid and triethanolamine to the latex, stir and mix to obtain latex B; S6 takes latex B in small amounts and grinds it several times at room temperature to obtain a UV matte coating.

2. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 1, characterized in that: The preparation method of the matting powder is specifically performed as follows: S11: talcum powder, barium sulfate, aluminum hydroxide and quartz powder are mixed in a ratio of 1.5-2.5:0.5-1:0.2-0.8:0.5-1.5 to obtain a mixed powder; S12 grinds the mixed powder, and then passes it through a 6000-mesh sieve to obtain a matte powder.

3. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 2, characterized in that: The grinding process is carried out in a planetary ball mill, and the ball milling speed is 600-900 r / min.

4. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 1, characterized in that: The preparation method of the emulsion is specifically performed as follows: S21 Add deionized water and dodecyl sulfuric acid into the emulsifying kettle, and stir and mix at 200-400 r / min for 15-25 min; S22: Continue to add waterborne polyurethane resin and active monomer, stir and mix for 20 minutes to obtain an emulsion.

5. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 4, characterized in that: The active monomer is any one of styrene, butadiene, acrylic acid and unsaturated carboxylic acid.

6. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 1, characterized in that: The mass volume ratio of the potassium persulfate to deionized water is 1:

10.

7. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 1, characterized in that: The method for obtaining latex by polymerization reaction is specifically performed as follows: firstly, 20% of emulsion and 25% of initiating liquid are added, and the reaction is carried out by heat preservation for 30 minutes, and then the remaining emulsion and initiating liquid are added dropwise, and the reaction is carried out by heat preservation for 2 hours to obtain latex; During the process of dripping the remaining emulsion and the remaining initiating solution, the reaction temperature is 80-86°C, the dripping time is 3-4 hours, and the insulation temperature is 86-88°C.

8. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 1, characterized in that: The nano titanium dioxide is prepared by using tetrabutyl titanate and anhydrous ethanol, and the specific operation is as follows: Step 1: Tetrabutyl titanate and anhydrous ethanol are mixed and stirred to prepare solution A; deionized water and anhydrous ethanol are mixed and nitric acid is added dropwise to adjust the pH value to 3-4 to prepare solution B; Step 2: Add solution A dropwise into solution B at room temperature while stirring, so that solution A and solution B are hydrolyzed and polycondensed to form a light yellow transparent sol; Step 3: Dry the sol in a drying oven at 80° C. for 24 h to form a gel, place the gel in a high-temperature furnace and heat it to 500° C. for heat treatment, and keep it warm for 2 h to obtain nano titanium dioxide powder.

9. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to claim 8, characterized in that: The film-forming aid is at least one of ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether and propylene glycol butyl ether; The photoinitiator is any one of diaryliodonium salt I-250, α-aminoalkylphenone, methyl benzoylformate and 2-hydroxy-2-methyl-1-phenylpropanone.

10. The method for preparing the stain-resistant and wipe-resistant water-based UV matte coating according to any one of claims 1 to 9, characterized in that: The UV matte coating prepared by the preparation method has the following composition in parts by weight: 30-60 parts of waterborne polyurethane resin, 20-40 parts of active monomer, 1-4 parts of sodium dodecyl sulfate, 2-6 parts of potassium persulfate, 10-18 parts of matting powder, 7-12 parts of nano titanium dioxide, 1-5 parts of triethanolamine, 0.5-2 parts of photoinitiator, 3-6 parts of film-forming aid and 50-80 parts of deionized water.

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