Waterborne polyurethane acrylate hybrid self-extinction coating as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a waterborne polyurethane acrylate hybrid self-extinction coating. The preparation method comprises the following steps: in a stirring state, reacting diisocyanate with polyether polyol at 65-75 DEG C for 2-4 hours, then adding an anionic hydrophilic chain extender at 70-80 DEG C, reacting with a polyfunctional group crosslinking monomer for 3-5 hours, introducing a hydrophilic carboxyl group to a molecular chain, and improving the crosslinking degree of a system; acrylate monomers are added in the polymerization process; reacting for 1-2 hours, and then carrying out end capping treatment at 60-75 DEG C; and neutralizing and emulsifying to obtain a waterborne polyurethane emulsion, and reacting for 7-8 hours under the action of a free radical initiator at the temperature of 65-75 DEG C to obtain the waterborne polyurethane acrylate hybrid self-extinction coating. The prepared paint is coated on glossiness detection test paper, and is naturally dried in a room temperature environment to obtain a self-extinction coating, and the coating has low glossiness and good water resistance and thermal stability at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of acrylate-modified waterborne polyurethane, and particularly relates to a waterborne polyurethane acrylate hybrid self-matting coating, a preparation method thereof, and application thereof in a self-matting coating. Background Art

[0002] With the development of the economy and the improvement of living standards, people's aesthetic requirements have also been further improved. Although bright and beautiful high-gloss paints are more popular in some aspects, the high-gloss surface is easy to show scratches and stains, difficult to clean and repair, and has high long-term maintenance costs. In places with high comfort requirements, such as children's rooms and hospitals, strong reflections can easily cause visual fatigue and high-gloss surfaces can cause light pollution. During the construction process, high gloss has extremely high requirements for the flatness of the base layer and the smoothness of the surface. If it is not handled properly, it is easy to cause defects such as sand marks and negative lumps, which affect the appearance and reduce the service life. Therefore, matte coatings are more comfortable and safe. Compared with high-gloss coatings, they are easy to clean and can even out the surface through microscopic roughness to conceal the defects of the substrate. Matt coatings have become a research hotspot in the coatings industry.

[0003] Matting paint generally achieves its matting effect in two ways: adding matting fillers such as silica, paraffin, etc. These matting fillers are light in weight and easily float to the surface of the film during the polymer film formation process to achieve a matting effect; the other method is to adjust the molecular structure of the paint to achieve a matting effect without adding any matting fillers. This type of paint is also called self-matting paint.

[0004] Chinese invention patent CN202310722736.9 discloses a method for preparing self-matting light-curing coatings and UV matte coatings. This method mainly uses modified TDI isocyanurate, modified TDI monomer and free fumed silica substrate. Through ultraviolet curing, the diffuse reflection of matte powder and the structural differences of the coating itself are used to reduce the gloss, which can achieve rapid curing while ensuring the high hardness of the coating. Since matte powder is an inorganic filler, the difference in compatibility will seriously affect the appearance of the coating, and the mechanical properties will also decrease. In addition, matte powder is difficult to exist stably in the coating, and particles are prone to aggregation to form precipitation. The uneven distribution of particles will also make the gloss of the coating uneven. Therefore, there are problems such as poor long-term stability and limited application scenarios.

[0005] Chinese invention patent CN202210296291.8 discloses a method for preparing a two-component, high-transparency matte varnish. This technology uses a two-component self-matting coating and an isocyanate curing agent. After curing, this method can form a strong and tough paint film with excellent scratch resistance, water boiling resistance, and chemical corrosion resistance. However, the isocyanate curing agent is highly toxic and can cause physical discomfort and health problems to production and construction workers. In addition, when the two components are mixed and stored, the fast-acting component is susceptible to high-temperature pre-reaction, resulting in a decrease in gloss, orange peel or sand grain phenomena, requiring a shortened turnover time or controlled storage temperature.

[0006] In waterborne polyurethane self-matting coatings, existing technologies struggle to achieve a low gloss coating, while maintaining emulsion stability, high-temperature resistance, and good coating hardness. Against this backdrop, developing waterborne polyurethane self-matting coatings with excellent stability, minimal environmental impact, simple production processes, and reasonable heat and water resistance is of great value. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides an environmentally friendly water-based polyurethane acrylate hybrid self-matting coating and a preparation method thereof. The coating prepared from the coating has self-matting properties and excellent stability, and also has good heat and water resistance.

[0008] Another object of the present invention is to provide a use of the waterborne polyurethane acrylate hybrid self-matting coating in the preparation of a self-matting coating.

[0009] To achieve the purpose of the present invention, the technical solutions adopted are as follows:

[0010] A method for preparing a waterborne polyurethane acrylate hybrid self-matting coating comprises the following steps:

[0011] 1) After uniformly stirring the diisocyanate and the polyether polyol, a metal organic catalyst is added and the mixture is reacted at 65-75° C. for 2-4 hours to obtain a linear isocyanate-terminated polyurethane prepolymer, wherein the molar ratio of the diisocyanate to the polyether polyol is controlled to be 1.5:0.6-0.8;

[0012] 2) adding an anionic hydrophilic chain extender and a crosslinking monomer to the linear isocyanate-terminated polyurethane prepolymer, and reacting at 70-80° C. for 3-5 hours to obtain a polyurethane prepolymer;

[0013] 3) adding acrylate monomer to the polyurethane prepolymer prepared in step 2) and continuing the reaction for 1 to 2 hours;

[0014] 4) cooling the product obtained in step 3) to 60-75° C., adding a hydroxyl-containing acrylate and reacting for 3-5 hours, cooling to room temperature, adding a neutralizer and neutralizing to a pH of 7-8, adding deionized water, stirring and emulsifying to obtain an aqueous polyurethane emulsion with unsaturated carbon-carbon double bonds as terminal groups;

[0015] 5) adding an initiator to the aqueous polyurethane emulsion having an unsaturated carbon-carbon double bond as the terminal group, reacting at 65-75° C. for 7-9 hours, and cooling to obtain an aqueous polyurethane acrylate hybrid self-matting coating.

[0016] To further achieve the purpose of the present invention, preferably, the molar ratio of the diisocyanate, the anionic hydrophilic chain extender, the crosslinking monomer, and the hydroxyl-containing acrylate is: 1.5:0.1-0.3:0.2-0.3:2-4.

[0017] Preferably, the diisocyanate is one of isophorone diisocyanate and hexamethylene diisocyanate; the polyether polyol is one of polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and the molecular weight of the polyether polyol is 400-1500.

[0018] Preferably, the anionic hydrophilic chain extender is one of 2,2-dihydroxymethylpropionic acid and 2,2-dihydroxymethylbutanoic acid; and the metal organic catalyst is one of dibutyltin dilaurate, bismuth carboxylate and stannous octoate.

[0019] Preferably, the hydroxyl-containing acrylate is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxyethyl methacrylate.

[0020] Preferably, the cross-linking monomer is one of trimethylolpropane, glycerol and pentaerythritol.

[0021] Preferably, the acrylate monomer is one or more of methyl methacrylate, ethyl acrylonitrile acrylate, butyl acrylate, and isooctyl acrylate; and the mass ratio of the acrylate monomer to the diisocyanate is 1.2:1 to 1.5:1.1.

[0022] The initiator is one or more of ammonium persulfate, potassium persulfate and sodium persulfate; the mass ratio of the initiator to the diisocyanate is 0.004:1 to 0.005:1.3.

[0023] Preferably, the neutralizing agent is one or more of ammonia, diethanolamine, and triethylamine; the amount of the neutralizing agent added controls the pH of the system to be 7.2 to 7.7; the mass ratio of deionized water to diisocyanate is 9.5:1.3 to 10:1.5;

[0024] In step 4), the stirring speed is 1800-3000 r / min.

[0025] A waterborne polyurethane acrylate hybrid self-matting coating is prepared by the above preparation method.

[0026] Application of the waterborne polyurethane acrylate hybrid self-matting coating in the preparation of a self-matting coating.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1) The present invention introduces unsaturated double bonds into the polyurethane main chain during the end-capping stage and connects the acrylate monomer to the polyurethane main chain structure through a free radical initiator. Since the acrylate monomer in the reaction process has no reaction activity in the system before the addition of the initiator and is a good solvent for the polyurethane prepolymer, it can be regarded as a solvent-free polymerization.

[0029] 2) The waterborne polyurethane prepolymer prepared in this invention is modified with an acrylate monomer, which, unlike traditional waterborne polyurethane self-matting coatings, offers improved water and heat resistance. The introduction of acrylates also provides more crosslinking sites, ensuring large-particle matting while also preventing uneven film shrinkage during film formation, further increasing microscopic surface roughness.

[0030] 3) Compared with CN202210296291.8, the single-component coating has lower cost, does not have the problem of pre-reaction of fast components at high temperatures, has better stability, does not form orange peel and sand texture appearance, has a simpler process, and because the system does not contain organic solvents, it is more friendly to production and construction personnel.

[0031] 4) Compared with CN202310722736.9, no additional matting powder is required, the long-term stability is better, the application scenarios are wider, and it is low-cost and environmentally friendly.

[0032] 5) The coating formed by the waterborne polyurethane acrylate hybrid self-matting coating of the present invention has excellent comprehensive performance, low gloss, and a hardness of 2H, good water resistance, and excellent thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the preparation method of the waterborne polyurethane acrylate hybrid self-matting coating corresponding to Example 1.

[0034] Figure 2 This is a total reflection infrared spectrum diagram comparing the self-matting coating prepared in Example 1 with a traditional waterborne polyurethane self-matting coating.

[0035] Figure 3 This is a thermogravimetric comparison chart of the self-matting coating prepared in Example 1 and the traditional waterborne polyurethane self-matting coating.

[0036] Figure 4 This is a thermogravimetric comparison chart of the self-matting coating prepared in Example 1 and the traditional waterborne polyurethane self-matting coating.

[0037] Figure 5 This is a stability test chart of the self-matting coating prepared in Example 1 after being left at room temperature for 3 months.

[0038] Figure 6 This is a diagram showing the gloss reduction effect of the self-matting coating prepared in Example 1 using a glass slide as the substrate.

[0039] Figure 7 The self-matting coating prepared in Example 1 is based on professional test paper and tested by a gloss meter. DETAILED DESCRIPTION

[0040] In order to better understand the present invention, the present invention is further described in detail below with reference to the embodiments. However, the scope of protection claimed by the present invention is not limited to the scope represented by the embodiments.

[0041] like Figure 1 As shown in the flow chart, the present invention first reacts isocyanate substances with polyols, and the isocyanate groups and hydroxyl groups react to form linear terminal isocyanate group prepolymers. Then, anionic hydrophilic chain extenders and cross-linking monomers are added. The hydroxyl groups at both ends of the hydrophilic chain extender further react with the isocyanate groups, and the carboxyl groups on the hydrophilic chain extender are introduced into the polyurethane molecular chain to improve the hydrophilicity of the polyurethane and achieve self-emulsification. The cross-linking monomer can increase the emulsion particle size and better achieve the self-extinction effect. In the final end-capping stage, hydroxyethyl acrylate containing a double bond and an acrylate monomer are added to react the remaining isocyanate groups. The former gives the polyurethane a polymerizable functional group, while the latter can reduce the viscosity of the system, making the reaction more controllable.

[0042] The waterborne polyurethane prepolymer prepared by the present invention is modified with an acrylate monomer. Unlike traditional waterborne polyurethane self-matting coatings, the introduction of the acrylate monomer enhances the system's crosslinking degree and the hydrophobic monomer, thereby enhancing water resistance. Furthermore, the covalent crosslinking network of the acrylate reduces chain breakage or oxidation reactions of the polyurethane at high temperatures. Acrylates themselves have good thermal stability, thus improving heat resistance. The introduction of the acrylate also provides more crosslinking sites, which not only ensures large-particle matting but also reduces uneven shrinkage of the film during film formation, further increasing microscopic surface roughness.

[0043] The coating obtained by the present invention is coated on a gloss test paper using a four-sided film applicator to a controlled thickness of 10 to 15 μm, and then naturally cooled and dried at room temperature to obtain a water-based polyurethane acrylate hybrid self-matting coating. The coating can form a coating without any auxiliary materials and can be simply operated. The coating is evenly spread using the film applicator. Since the film applicator can control the formed coating thickness to the micron level, the solvent can be completely evaporated within one hour. After the solvent evaporates, due to the cross-linked structure of the solvent and the presence of a large number of latex particles in the emulsion, these latex particles can be spread flat on the surface to form a coating structure.

[0044] Example 1

[0045] like Figure 1 As shown, a method for preparing a waterborne polyurethane acrylate hybrid self-matting coating comprises the following steps:

[0046] (1) Under stirring at 260 r / min, 12.48 g of isophorone diisocyanate and 23.25 g of polytetrahydrofuran (molecular weight 1000) were stirred uniformly, and 0.01 g of catalyst dibutyltin dilaurate was added. The mixture was reacted at 75°C for 2 h to obtain a linear isocyanate-terminated polyurethane prepolymer;

[0047] (2) adding 0.75 g of 2,2-dihydroxymethylpropionic acid and 0.37 g of trimethylolpropane to the polyurethane prepolymer obtained in step (1), reacting at 80° C. for 3 h to obtain a polyurethane prepolymer, and adding 3 g of methyl methacrylate and 2 g of butyl acrylate during the reaction to reduce the viscosity of the system;

[0048] (3) Cooling to 65° C., adding 5.37 g of hydroxyethyl acrylate to the reaction system, and reacting for 3 h to obtain a carbon-carbon double bond-terminated polyurethane prepolymer;

[0049] (4) The prepolymer prepared in step (3) was cooled to room temperature, and 0.69 g of triethylamine was added to neutralize it to a weak alkaline pH of 7.6, followed by the addition of 100 g of deionized water, and emulsification was completed under high-speed stirring to obtain an aqueous polyurethane emulsion.

[0050] (5) Add 3 g of methyl methacrylate and 2 g of butyl acrylate to the aqueous polyurethane emulsion obtained in step (4), add 0.06 g of potassium persulfate to initiate free radical polymerization, and react at 70° C. for 7 h to obtain a waterborne polyurethane acrylate hybrid self-matting coating.

[0051] After drying the waterborne polyurethane acrylate hybrid self-matting coating, a film can be obtained. The total reflection infrared spectra of the conventional waterborne polyurethane self-matting coating film and the film obtained by the present invention are shown in FIG. Figure 2 As shown. For traditional waterborne polyurethane self-matting coatings, 2252 cm-1 The characteristic peak of the isocyanate group is 3332 cm. The absence of an absorption peak here indicates that the isocyanate has been completely consumed. -1 and 1715cm -1 The absorption peaks at 1103 cm correspond to the stretching vibrations of NH and C=O, respectively. The characteristic group corresponds to the carbamate group, which also indicates that the isocyanate group reacts with the hydroxyl and amino groups to generate carbamate (-NH-CO-O-) and urea (-NH-CO-NH-). -1 The corresponding characteristic absorption peak of ether oxygen bond is between 3300 and 3500 cm -1 Both exhibit strong absorption peaks, typical of amino (NH) stretching vibrations. Waterborne polyurethane molecular chains contain numerous hydrophilic amino and carboxylic acid groups, leading to significant absorption in this region. However, the strength of waterborne polyurethane acrylate hybrid self-matting coatings is significantly lower than that of unmodified waterborne polyurethane, as some amino groups may participate in crosslinking or be diluted during the modification process. This is also a distinguishing characteristic of hybrid emulsions.

[0052] Thermodynamic stability tests of conventional waterborne polyurethane self-matting coating and the coating obtained by the present invention are as follows: Figure 3 、 Figure 4 As shown in the two figures, the heat resistance of the material is significantly improved after the addition of acrylate. At 400°C, the mass residual rate of WPU is 20%, while that of WPUA increases to 40%. At 600°C, WPU is completely decomposed, the residual rate is close to 0, while WPUA retains 10-15%; the mass change rate of WPU rises rapidly after 400°C, and the mass change rate of WPUA rises less after 400°C, and tends to be stable at high temperatures (>500°C), indicating that its residue has higher thermal stability and the decomposition rate is significantly reduced. Therefore, it can be proved that the introduction of acrylate monomer improves the heat resistance of waterborne polyurethane.

[0053] Example 2

[0054] A method for preparing a waterborne polyurethane acrylate hybrid self-matting coating comprises the following steps:

[0055] (1) While stirring, 13.21 g of isophorone diisocyanate and 23.25 g of polytetrahydrofuran (molecular weight 1000) were uniformly stirred, and 0.01 g of dibutyltin dilaurate as a catalyst was added. The mixture was reacted at 75° C. for 2 h to obtain a linear isocyanate-terminated polyurethane prepolymer.

[0056] (2) adding 0.75 g of 2,2-dihydroxymethylpropionic acid and 0.37 g of trimethylolpropane to the polyurethane prepolymer obtained in step (1), reacting at 80° C. for 3 h to obtain a polyurethane prepolymer, and adding 3 g of methyl methacrylate and 2 g of butyl acrylate during the reaction to reduce the viscosity of the system;

[0057] (3) Cooling to 65° C., adding 6.1 g of hydroxyethyl acrylate to the reaction system, and reacting for 3 h to obtain a carbon-carbon double bond-terminated polyurethane prepolymer;

[0058] (4) The prepolymer prepared in step (3) was cooled to room temperature, and 0.69 g of triethylamine was added to neutralize it to a weak alkaline pH of 7.8, followed by the addition of 100 g of deionized water, and emulsification was completed under high-speed stirring to obtain an aqueous polyurethane emulsion.

[0059] (5) Add 3 g of methyl methacrylate and 2 g of butyl acrylate to the aqueous polyurethane emulsion obtained in step (4), add 0.06 g of potassium persulfate to initiate free radical polymerization, and react at 70° C. for 7 h to obtain a waterborne polyurethane acrylate hybrid self-matting coating.

[0060] Example 3

[0061] A method for preparing a waterborne polyurethane acrylate hybrid self-matting coating comprises the following steps:

[0062] (1) Under stirring, 13.95 g of isophorone diisocyanate and 23.25 g of polytetrahydrofuran (molecular weight 1000) were stirred uniformly, and 0.01 g of catalyst dibutyltin dilaurate was added. The mixture was reacted at 75° C. for 2 h to obtain a linear isocyanate-terminated polyurethane prepolymer.

[0063] (2) adding 0.75 g of 2,2-dihydroxymethylpropionic acid and 0.37 g of trimethylolpropane to the polyurethane prepolymer obtained in step (1), reacting at 80° C. for 3 h to obtain a polyurethane prepolymer containing hydrophilic carboxyl groups on the molecular chain and having a certain cross-linking structure, and adding a certain amount of methyl methacrylate and butyl acrylate during the reaction to reduce the viscosity of the system;

[0064] (3) Cooling to 65° C., adding 6.9 g of hydroxyethyl acrylate to the reaction system, and reacting for 3 h to obtain a carbon-carbon double bond-terminated polyurethane prepolymer;

[0065] (4) The prepolymer prepared in step (3) was cooled to room temperature, and 0.69 g of triethylamine was added to neutralize it to a weak alkaline pH of 7.4, followed by the addition of 100 g of deionized water, and emulsification was completed under high-speed stirring to obtain an aqueous polyurethane emulsion.

[0066] (5) Add 3 g of methyl methacrylate and 2 g of butyl acrylate to the aqueous polyurethane emulsion obtained in step (4), add 0.07 g of ammonium persulfate to initiate free radical polymerization, and react at 70° C. for 7 h to obtain a waterborne polyurethane acrylate hybrid self-matting coating.

[0067] Comparative Example 1

[0068] (1) Under stirring, 14.67 g of isophorone diisocyanate and 23.25 g of polytetrahydrofuran (molecular weight 1000) were stirred uniformly, and 0.01 g of catalyst dibutyltin dilaurate was added. The mixture was reacted at 75°C for 2 h to obtain a linear isocyanate-terminated polyurethane prepolymer;

[0069] (2) adding 0.75 g of 2,2-dihydroxymethylpropionic acid and 0.37 g of trimethylolpropane to the polyurethane prepolymer obtained in step (1), reacting at 80° C. for 3 h to obtain a polyurethane prepolymer, and adding a certain amount of methyl methacrylate and butyl acrylate during the reaction to reduce the viscosity of the system;

[0070] (3) Cooling to 65° C., adding 7.63 g of hydroxyethyl acrylate to the reaction system, and reacting for 3 h to obtain a carbon-carbon double bond-terminated polyurethane prepolymer;

[0071] (4) The prepolymer prepared in step (3) was cooled to room temperature, 0.69 g of triethylamine was added for neutralization, and then 100 g of deionized water was added, and emulsification was completed under high-speed stirring to obtain an aqueous polyurethane emulsion.

[0072] (5) The aqueous polyurethane emulsion obtained in step (4) was mixed with the remaining acrylate monomers, wherein the total mass of the acrylate monomers was 10 g and the ratio of methyl methacrylate to butyl acrylate was 3:2. 0.07 g of potassium persulfate was added to initiate free radical polymerization, and the mixture was reacted at 70° C. for 7 h to obtain a waterborne polyurethane acrylate hybrid self-matting coating.

[0073] Comparative Example 2

[0074] (1) Under stirring, 15.4 g of isophorone diisocyanate and 23.25 g of polytetrahydrofuran (molecular weight 1000) were stirred uniformly, and 0.01 g of catalyst dibutyltin dilaurate was added. The mixture was reacted at 75° C. for 3 h to obtain a linear isocyanate-terminated polyurethane prepolymer.

[0075] (2) adding 0.75 g of 2,2-dihydroxymethylpropionic acid and 0.37 g of trimethylolpropane to the polyurethane prepolymer obtained in step (1), reacting at 80° C. for 3 h to obtain a polyurethane prepolymer, and adding 10 g of acetone during the reaction to reduce the viscosity of the system;

[0076] (3) The prepolymer prepared in step (2) was cooled to room temperature, 0.69 g of triethylamine was added for neutralization, and then 100 g of deionized water was added, and emulsification was completed under high-speed stirring. During the emulsification process, hydrazine hydrate and sodium ethylenediaminesulfonate were added for post-chain extension to obtain an aqueous polyurethane emulsion.

[0077] Referring to GB / T 9754-2007, the 60° glossiness of the coating surface was measured using a YG60L gloss meter. The results are listed in Table 1.

[0078] The pencil hardness of the coating was measured using a QHQ-A pencil hardness tester according to GB / T 6739-2006. The results are listed in Table 1.

[0079] Referring to GB / T 1034-2008, the self-matting coating was immersed in deionized water and the water absorption rate of the sample was calculated. The results are listed in Table 1.

[0080] Referring to GB / T 11175-2021, the emulsion was centrifuged for 20 min using a small centrifuge to observe whether stratification or precipitation occurred. The results are listed in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] As can be seen from Table 1, the self-matting coating of the embodiment of the present invention has obvious comprehensive performance advantages. In terms of glossiness, since the acrylate-modified waterborne polyurethane has a core-shell structure, with polyacrylate as the core and polyurethane as the shell, especially this core-shell structure, the latex particles are directly accumulated on the surface of the substrate during film formation, forming a uniform and rough coating; wherein the latex particles with a micron-sized particle size can significantly increase the microscopic concavity and convexity of the surface, reduce the specular reflection of light, and thus reduce the glossiness. At the same time, during the modification process of the acrylate-modified waterborne polyurethane, the compatibility difference between acrylate and polyurethane and the chemical crosslinking effect will cause phase separation, forming an uneven microstructure (such as micro-wrinkles or layered structures). This micro-wrinkles or layered microstructures produce more diffuse reflections during drying and film formation, reducing the proportion of specularly reflected light, thereby achieving a self-matting effect. Furthermore, since acrylate monomers are hydrophobic, their addition enhances the coating's water resistance, and the cross-linked network structure also restricts the diffusion path of water molecules. Therefore, compared to the self-matting coating in Comparative Example 1, which was not modified with acrylate monomers, Example 1 exhibits lower gloss, lower water absorption, and improved coating hardness. It is also important to emphasize that this chemical cross-linking and micro-wrinkled or layered microscopic cross-linked structure also enhance the coating's mechanical properties.

[0085] pass Figure 3 、 Figure 4 It can also be found that the heat resistance of the material is significantly improved after the addition of acrylate. At 400°C, the residual mass of WPU is 20%, while that of WPUA increases to 40%. At 600°C, WPU completely decomposes, with the residual rate approaching 0, while WPUA retains 10-15%. The mass change rate of WPU increases rapidly after 400°C, while the mass change rate of WPUA increases less after 400°C and tends to stabilize at high temperatures (>500°C), indicating that its residue has higher thermal stability and a significantly reduced decomposition rate.

[0086] Figure 5 The test method is to cool the prepared paint and then let it stand at room temperature and natural light for 3 months. Without adding any other additives, it can be found that the paint does not show any stratification or precipitation, and the overall structure remains homogeneous, indicating that the paint has good storage stability under natural use.

[0087] Figure 6 The test method is to cool the paint after preparation, then drop it on a glass slide, and use a four-sided applicator to prepare a self-matting coating with a thickness of 15μm. Through the blank group control, it can be found that the gloss reduction effect is very significant, but the specific gloss value needs to be tested on a specific test paper using a gloss meter.

[0088] Figure 7 The test method is to cool the coating after preparation, drop it on the colorimetric test paper, use a four-sided film applicator to prepare a self-matting coating with a thickness of 15μm, and use a gloss meter to test the glossiness. The glossiness of the coating can reach 0.6GU at 60°. Figure 6 By supplementing the specific data, it can be found that the glossiness is significantly reduced, and the gloss reduction effect is more significant compared to conventional self-matting resin.

[0089] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a waterborne polyurethane acrylate hybrid self-matting coating, characterized in that The following steps are involved: 1) After uniformly stirring the diisocyanate and the polyether polyol, a metal organic catalyst is added and the mixture is reacted at 65-75° C. for 2-4 hours to obtain a linear isocyanate-terminated polyurethane prepolymer, wherein the molar ratio of the diisocyanate to the polyether polyol is controlled to be 1.5:0.6-0.8; 2) adding an anionic hydrophilic chain extender and a crosslinking monomer to the linear isocyanate-terminated polyurethane prepolymer, and reacting at 70-80° C. for 3-5 hours to obtain a polyurethane prepolymer; 3) adding acrylate monomer to the polyurethane prepolymer prepared in step 2) and continuing the reaction for 1 to 2 hours; 4) cooling the product obtained in step 3) to 60-75° C., adding a hydroxyl-containing acrylate and reacting for 3-5 hours, cooling to room temperature, adding a neutralizer and neutralizing to a pH of 7-8, adding deionized water, stirring and emulsifying to obtain an aqueous polyurethane emulsion with unsaturated carbon-carbon double bonds as terminal groups; 5) adding an initiator to the aqueous polyurethane emulsion having an unsaturated carbon-carbon double bond as the terminal group, reacting at 65-75° C. for 7-9 hours, and cooling to obtain an aqueous polyurethane acrylate hybrid self-matting coating.

2. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The molar ratio of the diisocyanate, the anionic hydrophilic chain extender, the crosslinking monomer, and the hydroxyl-containing acrylate is 1.5:0.1-0.3:0.2-0.3:2-4.

3. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The diisocyanate is one of isophorone diisocyanate and hexamethylene diisocyanate; the polyether polyol is one of polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and the molecular weight of the polyether polyol is 400-1500.

4. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The anionic hydrophilic chain extender is one of 2,2-dihydroxymethylpropionic acid and 2,2-dihydroxymethylbutanoic acid; and the metal organic catalyst is one of dibutyltin dilaurate, bismuth carboxylate and stannous octoate.

5. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The hydroxyl-containing acrylate is one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxyethyl methacrylate.

6. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The cross-linking monomer is one of trimethylolpropane, glycerol and pentaerythritol.

7. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The acrylate monomer is one or more of methyl methacrylate, ethyl acrylonitrile acrylate, butyl acrylate, and isooctyl acrylate; and the mass ratio of the acrylate monomer to the diisocyanate is 1.2:1 to 1.5:1.

1. The initiator is one or more of ammonium persulfate, potassium persulfate and sodium persulfate; the mass ratio of the initiator to the diisocyanate is 0.004:1 to 0.005:1.

3.

8. The method for preparing the waterborne polyurethane acrylate hybrid self-matting coating according to claim 1, characterized in that: The neutralizing agent is one or more of ammonia, diethanolamine, and triethylamine; the amount of the neutralizing agent added controls the pH of the system to be 7.2 to 7.7; the mass ratio of deionized water to diisocyanate is 9.5:1.3 to 10:1.5; In step 4), the stirring speed is 1800-3000 r / min.

9. A waterborne polyurethane acrylate hybrid self-matting coating, characterized in that The invention discloses a novel novel polyol according to claim 1 , wherein the polyol is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the waterborne polyurethane acrylate hybrid self-matting coating according to claim 9 in the preparation of a self-matting coating.

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