Aqueous polycarbonate polyol-modified hydroxy acrylic resin, method for producing the same, and coating

Abstract

The application discloses a water-based polycarbonate polyol modified hydroxyl acrylic resin, which comprises a wrapping structure formed by wrapping polycarbonate polyol with water and / or hydroxyl acrylic resin, and a plurality of the wrapping structures are bonded with each other to form a three-dimensional network structure. The application also provides a preparation method of the water-based polycarbonate polyol modified hydroxyl acrylic resin and a water-based matte black two-component polyurethane coating. The water-based polycarbonate polyol modified hydroxyl acrylic resin can be used to prepare the water-based matte black two-component polyurethane coating, and the gloss of the coating can be as low as 0.8-1°, and the coating can also meet the requirements of scratch resistance and chemical resistance.

Description

Technical Field

[0001] This invention belongs to the field of coatings, and particularly relates to a modified hydroxyl acrylic resin and its preparation method, as well as polyurethane coatings. Background Technology

[0002] Matte black paint, due to its low gloss and visually striking deep black finish, is widely used in the 3C electronics and automotive industries. However, because of its low gloss, this coating is prone to scratches when applied to frequently touched components such as interior and exterior parts of 3C electronics and automobiles, significantly impacting the coating's decorative effect and protection lifespan. Therefore, current matte black paints have very high requirements for scratch resistance. To improve scratch resistance, the coating gloss is often reduced to within the range of 2-3 degrees, sacrificing some of the visually striking deep black surface finish.

[0003] Matte black coatings are generally divided into UV-cured and two-component polyurethane types. UV-cured coatings are limited in application due to factors such as material type, thickness, and shape, while two-component polyurethane coatings are less restricted and are the most widely used. Currently, solvent-based matte black two-component polyurethane coatings are gradually being replaced by water-based matte black two-component polyurethane coatings because of their high VOC content and environmental unfriendliness. Currently, water-based matte black two-component polyurethane coatings typically use either polycarbonate polyurethane or hydroxyl acrylic coatings. Polycarbonate polyurethane coatings offer good scratch resistance but have poor chemical resistance, while hydroxyl acrylic coatings offer good chemical resistance but poor scratch resistance. Therefore, existing water-based matte black two-component polyurethane coatings struggle to simultaneously meet both scratch resistance and chemical resistance requirements, limiting their further development and application. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a waterborne polycarbonate polyol-modified hydroxyl acrylic resin and its preparation method, as well as a waterborne matte black two-component polyurethane coating. The waterborne matte black two-component polyurethane coating obtained using this waterborne polycarbonate polyol-modified hydroxyl acrylic resin can achieve a gloss level as low as 0.8-1°, while simultaneously meeting the requirements of scratch resistance and chemical resistance. To solve the above technical problem, the technical solution proposed by this invention is as follows:

[0005] A waterborne polycarbonate polyol modified hydroxyl acrylic resin includes a polycarbonate polyol encapsulation structure formed by water and / or hydroxyl acrylic resin encapsulating the polycarbonate polyol, wherein multiple encapsulation structures are bonded to each other to form a three-dimensional network structure.

[0006] The aforementioned encapsulation structures mainly refer to structures formed by water encapsulating polycarbonate polyols, or hydroxyl acrylic resin encapsulating polycarbonate polyols, or a combination of water and hydroxyl acrylic resin encapsulating polycarbonate polyols, with hydroxyl acrylic resin encapsulating polycarbonate polyols being the most common. Polycarbonate polyols possess self-emulsifying groups, which, during emulsification, are encapsulated by water or hydroxyl acrylic resin to form an "oil-in-water" structure, stabilizing them in the resin solution. These encapsulation structures are mutually bonded, interpenetrated, anchored, and entangled through hydrogen bonds and chemical bonds, forming a stable colloid, thus yielding a three-dimensional network structure. Coatings obtained using this structure have a larger molecular weight and are more dense after drying.

[0007] As a general technical concept, the present invention also provides a method for preparing the above-mentioned waterborne polycarbonate polyol modified hydroxyl acrylic resin, comprising the following steps:

[0008] (1) Heat the waterborne hydroxyl acrylic resin to 50±5℃ while stirring;

[0009] (2) Heat the polycarbonate polyol to 50±5℃, and then slowly add it to the waterborne hydroxy acrylic resin in step (1) under stirring, so that the waterborne hydroxy acrylic resin can fully emulsify the polycarbonate polyol until it is milky white.

[0010] (3) Heat the rheology modifier to 50±5℃, and then add it to the milky white reaction system in step (2) with stirring. After dispersion, cool down to obtain waterborne polycarbonate polyol modified hydroxy acrylic resin.

[0011] In the above preparation method, the temperature of each step needs to be controlled. If the temperature is too low, the polycarbonate partial emulsification reaction will directly combine with water, and a three-dimensional network structure cannot be fully formed, affecting chemical resistance and scratch resistance. If the temperature is too high, the formed colloidal state will be destroyed, and a homogeneous and stable structure cannot be formed.

[0012] In the above preparation method, preferably, the weight ratio of waterborne hydroxyl acrylic resin, polycarbonate polyol, and rheology modifier one is controlled as 75-85 parts: 15-25 parts: 0.2-0.3 parts. If the proportion of hydroxyl acrylic resin is too high, the proportion of polycarbonate will be too low, affecting the scratch resistance; conversely, it will affect the chemical resistance. If the proportion of rheology modifier one is too high, the viscosity will be too high; if the proportion is too low, the viscosity will be too low. Both will affect the final application and the storage stability of the resin solution itself.

[0013] In the above preparation method, preferably, the waterborne hydroxy acrylic resin is Yuanhe Chemical ACURE911; the polycarbonate polyol is Asahi Kasei AK011; and the rheology modifier is Wanhua Chemical U300.

[0014] The waterborne hydroxyl acrylic resin used in this invention is Yuanhe Chemical's ACURE911, with a molecular weight ranging from tens of thousands to hundreds of thousands, making it a high molecular weight resin. Its solid content is ≥43%, and its hydroxyl content is ≥3.7%. The high hydroxyl content does not affect adhesion to PC or ABS materials. During drying and curing, the coating formed by the reaction with isocyanate has a higher crosslinking density and molecular weight, thus exhibiting better resistance to chemical contamination and superior scratch resistance. After comparing various waterborne hydroxyl acrylic resins, Yuanhe Chemical's ACURE911 demonstrates superior performance.

[0015] The polycarbonate polyol used in this invention is Asahi Kasei AK011, with a molecular weight of 1000, a solid content of 100%, and a hydroxyl content of ≥3.3%. The high hydroxyl content and small molecular weight make it easier for the coating to form chemical bonds and penetrate into the material, thus providing excellent adhesion while maintaining a certain degree of resistance to chemical contamination. Due to the excellent elasticity and rapid recovery characteristics of polycarbonate polyol resin, the resulting coating has stronger scratch resistance and self-healing properties.

[0016] The rheology modifier used in this invention is Wanhua Chemical U300, a Newtonian nonionic polyurethane thickener. As a low-shear rheology modifier, it can stabilize the viscosity of the waterborne polycarbonate polyol-modified hydroxyl acrylic resin and impart a certain degree of thixotropy, maintaining the interwoven three-dimensional network structure of the waterborne polycarbonate polyol-modified hydroxyl acrylic resin. After comparing various rheology modifiers, Wanhua Chemical U300 shows relatively superior performance.

[0017] In the above preparation method, preferably, the stirring speed is controlled at 600-800 rpm during stirring in step (1); the stirring speed is controlled at 600-800 rpm during stirring in step (2), and the material fineness is ≤15 μm and there is no transparent resin in the milky white reaction system; the stirring speed is controlled at 800-1000 rpm during stirring in step (3), and after stirring and dispersing, the viscosity of the reaction system at 25℃ is 500±100 CPS.

[0018] The waterborne polycarbonate polyol modified hydroxy acrylic resin of this invention uses high molecular weight waterborne hydroxy acrylic resin and water as a dispersion medium. At 50±5℃, low molecular weight polycarbonate polyol with self-emulsifying groups reacts with waterborne hydroxy acrylic resin and water to form an interwoven three-dimensional network structure. Compared to simply using water as a medium, the "oil-in-water" resin system formed by stirring and emulsifying polycarbonate polyol at room temperature, followed by mechanical mixing with waterborne hydroxy acrylic resin, does not form an interwoven three-dimensional network structure. The resulting coating lacks density after drying and cannot effectively resist the erosion of sunscreen and yellow mustard. This invention pre-emulsifies polycarbonate polyol and waterborne hydroxy acrylic resin at a controlled temperature, forming a dense three-dimensional network structure with interwoven molecules of varying sizes. The resulting coating has a larger molecular weight and is denser, preventing sunscreen and yellow mustard from penetrating into the coating, thus exhibiting better chemical resistance. The low molecular weight polycarbonate polyols of the present invention are interpenetrating and cross-linked, and are evenly distributed throughout the surface, middle and bottom layers of the coating. Therefore, even if the gloss is only 0.8-1°, only a small amount is needed to achieve the scratch resistance and self-healing properties inherent in the coating, and there is no significant impact on the chemical resistance of the coating.

[0019] As a general technical concept, the present invention also provides a water-based matte black two-component polyurethane coating, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight:

[0020] 60-70 parts of waterborne polycarbonate polyol modified hydroxyl acrylic resin;

[0021] 3-4 parts black paste;

[0022] Additive A: 23.7-40.1 parts;

[0023] Component B comprises the following raw materials in parts by weight:

[0024] 70-90 parts of isocyanate curing agent;

[0025] Additive B10-30 parts;

[0026] The waterborne polycarbonate polyol modified hydroxyl acrylic resin is the waterborne polycarbonate polyol modified hydroxyl acrylic resin mentioned above.

[0027] In the above-mentioned waterborne matte black two-component polyurethane coating, preferably, the black paste comprises the following components in parts by weight: 18-22 parts carbon black, 15-25 parts waterborne dispersant, 3-8 parts solvent, and 50-60 parts deionized water; wherein the carbon black is Raven 5000 Ultra II, the waterborne dispersant is BYK DISPERBYK-199, and the solvent is propylene glycol.

[0028] In the above-mentioned water-based matte black two-component polyurethane coating, preferably, the preparation method of the black paste includes the following steps: adding solvent to deionized water under stirring at 400-600 rpm, dispersing for 3-5 minutes, and stirring evenly; then adding water-based dispersant under stirring at 600-800 rpm, dispersing for 8-10 minutes, and stirring evenly; then adding carbon black under stirring at 800-1000 rpm, dispersing for 8-10 minutes, and stirring evenly to obtain a mixture; finally, grinding the mixture 3-5 times in a sand mill with 1-3 mm zirconium beads until the fineness is ≤15 μm to obtain the black paste.

[0029] The black paste used in this invention is a self-made water-based black paste. The carbon black used in the water-based black paste of this invention is Raven 5000 Ultra II carbon black, with a total surface area of ​​583 m². 2 / g, external surface area 350m² 2 / g, tinting strength 135; the selected carbon black has an extremely high total surface area and external surface area, with stronger adsorption capacity, filling capacity, gloss reduction and enhanced visual blackness effect. Therefore, it can better adsorb resin and be filled and wrapped by resin, so that it does not float alone on the coating surface. To a certain extent, it can reduce the "gloss mark" caused by the carbon black being scratched off or the coating being depressed when touched by a fingernail, and improve the scratch resistance of the coating to a certain extent. With high tinting strength, high total surface area and external surface area, the visual blackness effect is stronger, and only a smaller amount needs to be added to achieve a matte black effect.

[0030] After comparing various carbon blacks, Raven 5000 Ultra II carbon black showed a better match with the other components of this invention.

[0031] The water-based black paste of this invention uses BYK Chemical DISPERBYK-199 as a dispersant. Its composition is a copolymer solution containing pigment affinity groups. Through the charge-steric stabilization effect, the carbon black reaches a deflocculated state with a small particle size, thus improving blackness and coating hiding power, further reducing the carbon black content, and achieving scratch resistance of the coating under low gloss.

[0032] The solvent used in the water-based black paste of the present invention is propylene glycol, which has excellent antifreeze and water absorption properties, thus providing stability and moisturizing properties to the black paste of the present invention.

[0033] The deionized water used in the water-based black paste of this invention is conventional deionized water.

[0034] In the aforementioned water-based matte black two-component polyurethane coating, preferably, additive A comprises the following components in parts by weight: 5.5-6.0 parts of matting agent, 0.2-0.3 parts of defoamer, 0.5-1 parts of substrate wetting agent one, 1-2 parts of substrate wetting agent two, 0.3-0.5 parts of rheology modifier two, 0.2-0.3 parts of drier, 3-5 parts of cosolvent one, 3-5 parts of cosolvent two, and 10-20 parts of deionized water; wherein the matting agent is one or both of Degussa ACEMATT TS100 and ACEMATT 3300, the defoamer is one or both of BYK-093 and Evonik Foamex 810, and the substrate wetting agent one is Evonik Tego. KL245, substrate wetting agent 2 is one or both of Air Chemical 104E and 104DPM, rheology modifier 2 is one or both of Wanhua Chemical U605 and BYK Chemical RHEOBYK-H 7625VF, drier is Borchers LH 10, cosolvent 1 is one or both of dipropylene glycol methyl ether and diethylene glycol butyl ether, and cosolvent 2 is one or both of dipropylene glycol butyl ether and propylene glycol butyl ether.

[0035] The matting powder used in this invention is one or both of Degussa ACEMATT TS100 and ACEMATT 3300, and its composition is untreated fumed silica with an average particle size of 8-12 μm. Because the untreated surface has a slightly larger average particle size and a higher oil absorption value, it can adsorb more water-based polycarbonate polyol modified hydroxyl acrylic resin, resulting in faster matting efficiency. Therefore, a small amount is sufficient to achieve a lower gloss of 0.8-1°. At the same time, the untreated surface of the matting powder does not have any wax treatment or organic treatment that is detrimental to scratch resistance. Encapsulated by the resin of this invention, when scratched by a fingernail, it will not cause a "gloss mark" due to the matting powder or surface treatment agent being scratched off or the coating being depressed, thus greatly improving the scratch resistance of the coating.

[0036] The defoamer used in this invention is one or both of BYK-093 from BYK Chemical and Foamex 810 from Evonik. The water-based defoamer of this invention includes polysiloxane or a mixture of polysiloxane and hydrophobic solids. It has excellent rapid defoaming effect on both large and micro bubbles generated during the stirring and dispersion process of coating preparation and the dispersion process of matte powder. During the coating baking process, it can suppress the undesirable defects of "prickly heat" and "crater" effect caused by bubbles generated by the reaction of the coating or bubbles brought about by the application process, avoid poor appearance of the coating due to bubbles after drying, and greatly improve the matte black appearance of the coating.

[0037] The substrate wetting agents used in this invention include substrate wetting agent one and substrate wetting agent two. Substrate wetting agent one is Evonik Tego KL245, which is composed of a low molecular weight modified polyether siloxane copolymer. As a substrate wetting agent, its molecular weight is the smallest in its class, and it has excellent compatibility with the coating of this invention. Therefore, it has excellent wetting and flow effects on the substrate. When the resulting coating is tested for light transmittance, there will be no "pinhole" light leakage. Therefore, chemicals such as yellow mustard and sunscreen will not penetrate to the bottom layer of the coating or the substrate, thus improving the chemical resistance of the coating to a certain extent. Substrate wetting agent two is one or both of Air Chemical 104E and 104DPM. Its composition is an acetylenic diol surfactant with a special twin chemical structure with two hydrophilic groups and two lipophilic groups symmetrically arranged. Therefore, it has excellent dynamic wetting effect and can work synergistically with substrate wetting agent one to improve the wetting performance of the coating on the substrate, thereby assisting the coating to better wet the substrate and further avoiding the "pinhole" light leakage phenomenon of the coating.

[0038] The rheology modifier used in this invention is one or both of Wanhua Chemical U605 and BYK Chemical RHEOBYK-H 7625VF. Its components are high-efficiency pseudoplastic nonionic polyurethane thickeners. These rheology modifiers can provide strong medium-low shear thickening, as well as good leveling and anti-sagging properties in the coatings of this invention. This makes it easier for the coating to avoid uneven film thickness due to sagging during construction, which would affect the uniformity of the protective film on the substrate.

[0039] The drying agent used in this invention is Borchers LH 10, which is an organotin drying agent. It can strongly promote the cross-linking and curing of polycarbonate polyol groups with low reaction rate and activity in the resin of this invention with isocyanate, reduce drying time, and improve the scratch resistance and chemical resistance of the coating after the cross-linking reaction.

[0040] The cosolvents used in this invention include cosolvent one and cosolvent two. Cosolvent one is one or both of dipropylene glycol methyl ether and diethylene glycol butyl ether. It has a high boiling point, low evaporation rate, and good miscibility with water. It can assist in the film formation of the coating and slow down the surface drying time of the coating during application, avoiding application abnormalities caused by excessively fast surface drying. Cosolvent two is one or both of dipropylene glycol butyl ether and propylene glycol butyl ether. It has a high boiling point, low evaporation rate, poor miscibility with water, and good flow and leveling properties. It can make the coating smoother during application.

[0041] The deionized water used in this invention is conventional deionized water.

[0042] In the above-mentioned water-based matte black two-component polyurethane coating, preferably, the isocyanate curing agent is Wanhua Chemical. 269, Additive B is cosolvent three, and cosolvent three is propylene glycol diacetate.

[0043] The water-dispersible isocyanate curing agent used in this invention is from Wanhua Chemical. Type 269, its type is based on hexamethylene diisocyanate modified curing agent, with an NCO content of 18.8-19.8%. The selected curing agent structure reacts with the waterborne polycarbonate polyol modified hydroxyl acrylic resin of the present invention to form a longer three-dimensional network chain structure, thus further improving the chemical resistance of the coating. Moreover, carbon black and matting powder are affected by the longer three-dimensional network chain structure and cannot float on the coating surface, further reducing the "gloss mark" caused by the removal of carbon black and matting powder or the coating being depressed when scratched by a fingernail, which increases the gloss. It has a certain improvement on the scratch resistance of the coating. Based on the number of hydrophilic groups of the selected curing agent on the isocyanate molecule and the distribution of molecular chain segments, it has good dispersibility in water and is easier to disperse evenly when stirred, resulting in better reaction consistency of the formed coating.

[0044] The coating exhibits the best scratch resistance and chemical resistance after the curing agent of the present invention reacts with the resin of the present invention. Although the main categories are based on hexamethylene diisocyanate, the properties of hexamethylene diisocyanate obtained according to different modifying groups and synthesis processes vary greatly.

[0045] The cosolvent used in component B of this invention is propylene glycol diacetate, which has a low odor, low volatility, and is more environmentally friendly. It also has good dilution properties for isocyanates, making it easier to disperse evenly when mixed with component A.

[0046] This invention optimizes the structure and preparation process of waterborne polycarbonate polyol-modified hydroxyl acrylic resin to obtain a waterborne polycarbonate polyol-modified hydroxyl acrylic resin. When applied to a waterborne matte black two-component polyurethane coating, through synergistic effects with other components and by optimizing the types and proportions of these components, a coating with a low gloss level of 0.8-1° and simultaneously meeting the requirements of scratch resistance and chemical resistance can be obtained. It is important to emphasize that the waterborne hydroxyl acrylic resin, polycarbonate polyol, rheology modifier one, black paste, additive A, isocyanate curing agent, and additive B of this invention exhibit significant synergistic effects. The types of each component have also been optimized and selected. Through synergistic effects, a coating that simultaneously meets the requirements of scratch resistance and chemical resistance can be obtained.

[0047] Compared with the prior art, the advantages of the present invention are as follows:

[0048] 1. This invention optimizes the structure and preparation process of waterborne polycarbonate polyol modified hydroxyl acrylic resin to form an encapsulation structure of water and / or hydroxyl acrylic resin encapsulating polycarbonate polyol. Multiple encapsulation structures are bonded to each other to form a three-dimensional network structure. When used in waterborne matte black two-component polyurethane coatings, it imparts excellent scratch resistance and self-healing properties, without significantly affecting the chemical resistance of the coating.

[0049] 2. The water-based matte black two-component polyurethane coating of the present invention has good anti-scratch effect. When the water-based matte black two-component polyurethane coating of the present invention is applied to the substrate and scratched by a fingernail, there will be no obvious scratches. Even if it is scratched by other objects, as long as the coating is not damaged, the coating can self-repair within 24 hours, which greatly improves the decorative effect and protection of the coating.

[0050] 3. The water-based matte black two-component polyurethane coating of the present invention does not show a significant change in gloss after being scratched with a fingernail under conditions of 0.8-1°. It still maintains a matte visual effect within the range of 0.8-1° and will not increase the gloss of the coating due to scratching with a fingernail. The coating will not show a "bright mark" visually. Moreover, due to the lower gloss and better blackness, the sensory effect is very strong, and the visual effect brings a piano black impact, enhancing the decorative properties of the coating.

[0051] 4. The water-based matte black two-component polyurethane coating of the present invention has good chemical resistance. After applying yellow mustard to the surface and being exposed to 65°C / 95% humidity for 72 hours, the color difference change ΔE is ≤1.5. This improves the color change of the coating when it is contaminated by chemicals, greatly enhances the coating's resistance to food contamination, and prevents the coating from changing color significantly due to food contamination, thus expanding the application scenarios of the coating.

[0052] 5. The water-based matte black two-component polyurethane coating of the present invention can meet the requirement that after applying sunscreen, the surface does not show obvious changes and the adhesion is ≥4B after 24 hours at 80°C, and still maintains good adhesion. It improves the coating's resistance to pollution from skin care products and other chemicals. When the coating is contaminated by skin care products and other chemicals, the surface will not swell, wrinkle or peel off, thus expanding the application scenarios of the coating. Detailed Implementation

[0053] To facilitate understanding of the present invention, preferred embodiments will be described more fully and in detail below, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0054] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0055] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0056] Examples 1-4:

[0057] The raw materials of the water-based matte black two-component polyurethane coating of this embodiment include component A and component B; component A consists of: 60-70 parts of water-based polycarbonate polyol modified hydroxyl acrylic resin, 5.5-6.0 parts of matting agent, 0.2-0.3 parts of defoamer, 0.5-1 parts of substrate wetting agent one, 1-2 parts of substrate wetting agent two, 0.3-0.5 parts of rheology modifier two, 3-4 parts of black paste, 0.2-0.3 parts of drier, 3-5 parts of cosolvent one, 3-5 parts of cosolvent two, and 10-20 parts of deionized water; component B consists of: 70-90 parts of water-dispersible isocyanate curing agent and 10-30 parts of cosolvent three. The specific composition of component A in Examples 1-4 is shown in Table 1 below:

[0058] Table 1: Component A of the waterborne matte black two-component polyurethane coating in Example 1

[0059]

[0060]

[0061] Table 2: Component A of the waterborne matte black two-component polyurethane coating in Example 2

[0062]

[0063] Table 3: Component A of the waterborne matte black two-component polyurethane coating in Example 3

[0064]

[0065] Table 4: Component A of the waterborne matte black two-component polyurethane coating in Example 4

[0066]

[0067]

[0068] The specific components of component B in Examples 1-4 are shown in Table 5 below:

[0069] Table 5: Component B of the waterborne matte black two-component polyurethane coatings in Examples 1-4

[0070]

[0071] The preparation method of the self-made waterborne polycarbonate polyol modified hydroxyl acrylic resin in Examples 1-4 includes the following steps:

[0072] 1. Heat the water-based hydroxyl acrylic resin to 50°C while stirring at 700 rpm, and maintain the temperature at 50°C.

[0073] 2. Heat the polycarbonate polyol to 50°C and slowly add it to step 1 while stirring at 700 rpm. Allow the waterborne hydroxyl acrylic resin to fully emulsify the polycarbonate polyol until it turns milky white, forming a structure in which the waterborne hydroxyl acrylic resin encapsulates the polycarbonate polyol and the waterborne hydroxyl acrylic resin and polycarbonate polyol interpenetrate each other. Disperse for 30 minutes until the fineness is ≤15 μm and there is no transparent resin.

[0074] 3. Heat the rheology modifier to 50°C and add it to step 2 while stirring at 900 rpm. After dispersing for 10 minutes, cool it down to 25°C. The viscosity is 500±100 CPS (25°C). The waterborne polycarbonate polyol modified hydroxyl acrylic resin can then be obtained.

[0075] The raw material composition of the waterborne polycarbonate polyol modified hydroxyl acrylic resin in Examples 1-4 above is shown in Table 6 below.

[0076] Table 6: Raw material components of waterborne polycarbonate polyol modified hydroxyl acrylic resin

[0077] Preparation of raw materials Manufacturer Number of copies Waterborne hydroxyl acrylic resin Yuanhe Chemical ACURE911 80 Polycarbonate polyols Asahi Kasei AK011 20 Rheology modifier 1 Wanhua Chemical U300 0.2

[0078] In other embodiments, the raw material composition of the waterborne polycarbonate polyol modified hydroxyl acrylic resin may also be as shown in Table 7 below.

[0079] Table 7: Raw material components of waterborne polycarbonate polyol modified hydroxyl acrylic resin

[0080]

[0081]

[0082] Using the above-mentioned raw materials and preparation process of waterborne polycarbonate polyol modified hydroxyl acrylic resin, a stable colloid can be obtained, which includes a polycarbonate polyol encapsulation structure formed by water and / or hydroxyl acrylic resin encapsulating the polycarbonate polyol. Multiple encapsulation structures are bonded to each other to form a three-dimensional network structure.

[0083] The preparation method of the self-made black paste in Examples 1-4 includes the following steps:

[0084] 1. Add the solvent to the deionized water while stirring at 500 rpm, disperse for 4 minutes, and stir until homogeneous;

[0085] 2. Add the aqueous dispersant to step 1 at a stirring speed of 700 rpm, disperse for 6 minutes, and stir until homogeneous;

[0086] 3. Add the carbon black to step 2 while stirring at 900 rpm, disperse for 9 minutes, and stir until homogeneous;

[0087] 4. Grind the mixture from step 3 in a sand mill with 1-3mm zirconium beads 3-5 times until the fineness is ≤15um (temperature controlled ≤40℃ throughout the process) to obtain the black paste of this embodiment.

[0088] The raw material composition of the above-mentioned black paste is shown in Table 8 below:

[0089] Table 8: Raw material composition of black paste

[0090] Preparation of raw materials Manufacturer Number of copies carbon black Raven 5000 Ultra II from Bora Carbon Black 20 Aqueous dispersants BYK Chemicals' DISPERBYK-199 20 solvent Propylene glycol 5 Deionized water / 55

[0091] The preparation method of the water-based matte black two-component polyurethane coatings in Examples 1-4 includes the following steps:

[0092] Preparation of component A:

[0093] 1. Disperse the waterborne polycarbonate polyol modified hydroxyl acrylic resin at a stirring speed of 400 rpm for 2 minutes;

[0094] 2. Add the matting powder to step 1 while stirring at 700 rpm. Gradually increase the stirring speed to 900 rpm as the matting powder is added, disperse for 12 minutes, and stir evenly.

[0095] 3. Add the defoamer to step 2 while stirring at 900 rpm, disperse for 12 minutes, and stir until homogeneous;

[0096] 4. Mix cosolvent one, cosolvent two, and deionized water, then add the mixture to step 3 while stirring at 700 rpm. Disperse for 4 minutes and stir until homogeneous.

[0097] 5. Add substrate wetting agent one and substrate wetting agent two to step 4 in sequence at a stirring speed of 700 rpm, disperse for 6 minutes, and stir evenly;

[0098] 6. Add rheology modifier II to step 5 with a stirring speed of 700 rpm. As the viscosity increases, gradually increase the stirring speed to 1100 rpm, disperse for 10 minutes, and stir evenly.

[0099] 7. Add the black paste to step 6 while stirring at 900 rpm, disperse for 6 minutes, and stir until homogeneous;

[0100] 8. Reduce the temperature of the mixture from step 6 to 15°C, add the drier at a stirring speed of 900 rpm, disperse for 6 minutes, and stir until uniform; thus, component A of the water-based anti-scratch matte black two-component polyurethane coating can be obtained.

[0101] Preparation of component B:

[0102] 9. Add the above cosolvent three to the water-dispersible isocyanate at a stirring speed of 700 rpm, disperse for 10 minutes, and stir evenly; thus, component B of the water-based matte black two-component polyurethane coating can be obtained.

[0103] Of course, in other embodiments, other raw materials with similar properties can be used for each preparation. For example, the water-based hydroxy acrylic resin can also be Wanhua Chemical's Antkote 2706. The actual effect will be worse than Yuanhe Chemical's ACURE911, but it will still be better than the products in the prior art.

[0104] Comparative Examples 1-10:

[0105] The waterborne matte black two-component polyurethane coatings of Comparative Examples 1-10 include Component A and Component B. The raw materials and dosage of Component B are the same as those in Example 1. The differences between Component A and Example 1 are shown in Tables 9-18 below.

[0106] Table 9: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 1

[0107]

[0108] Table 10: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 2

[0109]

[0110]

[0111] Table 11: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 3

[0112]

[0113] Table 12: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 4

[0114]

[0115] Table 13: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 5

[0116]

[0117]

[0118] Table 14: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 6

[0119]

[0120] Table 15: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 7

[0121]

[0122] In this comparative example, the 50% aqueous polycarbonate polyol resin was prepared by self-emulsifying Asahi Kasei AK011 and water to form a resin solution with a content of 50%. The specific preparation method is as follows: deionized water is added to the polycarbonate polyol resin under stirring at 500 rpm, dispersed for 6 minutes, and stirred evenly to obtain the 50% aqueous polycarbonate polyol resin.

[0123] Table 16: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 8

[0124]

[0125] In this comparative example, when preparing component A, the self-made waterborne polycarbonate polyol used to modify the hydroxyl acrylic resin was directly mixed with the hydroxyl acrylic resin at room temperature using mechanical stirring.

[0126] Table 17: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 9

[0127]

[0128] Table 18: Component A of the waterborne matte black two-component polyurethane coating in Comparative Example 10

[0129]

[0130]

[0131] The specific application methods for the water-based matte black two-component polyurethane coatings used in Examples 1-4 and Comparative Examples 1-10 are as follows:

[0132] The waterborne matte black two-component polyurethane coatings prepared in Examples 1-4 and Comparative Examples 1-10 were mixed with component A, component B, and deionized water diluent in a ratio of 50:10:8. The mixture was then sprayed onto the surface of a plastic substrate or other substrate and baked at 75°C for 40 minutes to obtain a surface-dried waterborne scratch-resistant matte black two-component polyurethane coating. After baking at 75°C for another 12 hours, a completely dried waterborne matte black two-component polyurethane coating was obtained.

[0133] The fully dried water-based matte black two-component polyurethane coatings in Examples 1-4 can achieve a more visually black finish under low gloss conditions of 0.8-1°, exhibiting good scratch resistance and self-healing properties, minimal color difference from yellow mustard, and excellent adhesion to sunscreen. The main performance requirements are shown in Tables 19 and 20 below:

[0134] Table 19: Performance data of waterborne matte black two-component polyurethane coatings of Examples 1-4 and Comparative Examples 1-3

[0135]

[0136]

[0137] Table 20: Performance data of waterborne matte black two-component polyurethane coatings of Comparative Examples 4-10

[0138]

[0139]

[0140] Compared with Comparative Example 1, Comparative Example 1 has a lower content of matte powder than Example 1, so its gloss is higher than the standard range of 0.8-1°, which does not meet the low gloss requirement of water-based matte black two-component polyurethane coating, and the appearance of extreme black is not good enough; while the gloss of Example 1 is within the standard gloss requirement range.

[0141] Compared with Comparative Example 2, Comparative Example 2 has a higher content of matting powder than Example 1, so its gloss is lower than the standard range of 0.8-1°, failing to meet the low gloss requirement of water-based matte black two-component polyurethane coating. This is because the content of matting powder is too high, exceeding the range of matting powder content encapsulated in resin. Secondly, the low gloss makes scratches on the coating more visible when touched by a fingernail, resulting in a decrease in scratch resistance and self-healing properties. The color difference variation resistance to yellow mustard exceeds the standard range, failing to meet the standard requirements.

[0142] Compared with Comparative Example 3, the content of black paste in Comparative Example 3 is lower than that in Example 1, resulting in insufficient opacity of the coating. The coating will show through the substrate and fail to meet the standard opacity requirements.

[0143] Compared with Comparative Example 4, the content of black paste in Comparative Example 4 was higher than that in Example 1. This was because the content of black paste was too high, exceeding the range of carbon black powder content in the resin-encapsulated black paste, which led to a decrease in scratch resistance and self-healing performance, and the resistance to yellow mustard color difference changes exceeded the standard range, failing to meet the standard requirements.

[0144] Compared with Comparative Example 5, the content of the drier in Comparative Example 5 was lower than that in Example 1. Because the drier content was insufficient, the cross-linking reaction of the coating formed by the water-based resin and the isocyanate curing agent was incomplete, the coating density was insufficient, the gloss was low, and the chemicals would penetrate to the bottom of the coating, resulting in large color difference in resistance to yellow mustard and insufficient adhesion after sunscreen, only 2B.

[0145] Compared with Comparative Example 6, the content of the drying agent in Comparative Example 6 is higher than that in Example 1. Because the content of the drying agent is excessive, the coating formed by the water-based resin and the isocyanate curing agent undergoes excessive cross-linking and polymerization, resulting in a higher gloss and insufficient ultra-black appearance. This fails to meet the requirements of low gloss and ultra-black appearance of water-based scratch-resistant matte black two-component polyurethane coating.

[0146] Compared with Comparative Example 7, Example 1 involved conventionally emulsifying the polycarbonate polyol used in the self-made waterborne polycarbonate polyol-modified hydroxyl acrylic resin and then mechanically stirring it with the hydroxyl acrylic resin at room temperature. This did not allow the polycarbonate polyol, waterborne hydroxyl acrylic resin, and water to fully react and form an interwoven three-dimensional network structure. Therefore, Example 1 had slightly worse scratch resistance and self-healing properties than Example 1, less stable color difference against yellow mustard, and its sunscreen adhesion fluctuated between 2-4B. In contrast, Example 1 had a stable color difference ΔE against yellow mustard ≤1.5 and a stable adhesion after sunscreen application of 4B.

[0147] Compared with Comparative Example 8, Example 1, which uses self-made waterborne polycarbonate polyol to modify hydroxy acrylic resin, involves mechanically stirring the polycarbonate polyol and hydroxy acrylic resin at room temperature. This process cannot fully achieve the desired three-dimensional network structure formed by the reaction of polycarbonate polyol, waterborne hydroxy acrylic resin, and water. Therefore, Example 1 has slightly worse scratch resistance than Example 1, less stable color difference with yellow mustard, and fluctuates between 3-4B with sunscreen adhesion. In contrast, Example 1 has a stable color difference ΔE of ≤1.5 with yellow mustard and a stable adhesion of 4B after sunscreen application.

[0148] Compared with Comparative Example 9, the matting powder of Comparative Example 9 uses organically surface-treated precipitated silica, which has a lower matting efficiency than the matting powder of Example 1. Therefore, the gloss is higher and the visual blackness is insufficient. At the same time, when touched by a fingernail, the organic treatment layer on the surface of the matting powder is easily scratched off, resulting in a "bright mark" phenomenon. Scratches are more easily visible, leading to a decrease in scratch resistance and self-healing performance.

[0149] Compared with Comparative Example 10, the black paste of Comparative Example 10 uses ordinary carbon black, which has a smaller total surface area and outer surface area than the carbon black of Example 1. The tinting strength is also smaller than that of the carbon black of Example 1. The visual blackness and tinting power are reduced, so the opacity is insufficient and the substrate is exposed. At the same time, the adsorption capacity and filling capacity are also weaker than those of Example 1, so the scratch resistance is slightly worse than that of Example 1.

Claims

1. A process for the preparation of an aqueous polycarbonate polyol-modified hydroxyacrylic resin, characterized in that, The water-based polycarbonate polyol modified hydroxyl acrylic resin comprises a wrapped structure of water and / or hydroxyl acrylic resin wrapped polycarbonate polyol, and a plurality of the wrapped structures are bonded to each other to form a three-dimensional network structure; The preparation method comprises the following steps: (1) heating the water-based hydroxyl acrylic resin to 50±5°C under stirring; (2) heating the polycarbonate polyol to 50±5°C, then slowly adding it into the water-based hydroxyl acrylic resin in step (1) under stirring, and allowing the water-based hydroxyl acrylic resin to fully emulsify the polycarbonate polyol to a milky white color; (3) heating the rheological additive I to 50±5°C, then adding it into the milky white reaction system in step (2) under stirring, and cooling after dispersion, to obtain the water-based polycarbonate polyol modified hydroxyl acrylic resin; The weight ratio of the water-based hydroxyl acrylic resin, the polycarbonate polyol and the rheological additive I is 75-85:15-25:0.2-0.3; The water-based hydroxyl acrylic resin is ACURE 911 from Ronghe Chemical Industry Co., Ltd.; the polycarbonate polyol is AK011 from Asahi Kasei; and the rheological additive I is U300 from Wanhua Chemical Industry Co., Ltd.

2. The production method according to claim 1, characterized by, The stirring speed in step (1) is controlled to be 600-800 rpm; The stirring speed in step (2) is controlled to be 600-800 rpm, and the stirring dispersion is performed until the fineness of the material in the milky white reaction system is ≤15 um and there is no transparent resin; The stirring speed in step (3) is controlled to be 800-1000 rpm, and the viscosity of the reaction system after stirring dispersion is 500±100 CPS at 25°C.

3. A waterborne matte black two-component polyurethane coating, characterized in that, The A component and the B component are included, and the A component comprises the following raw materials in parts by weight: The water-based polycarbonate polyol modified hydroxyl acrylic resin is 60-70 parts; The black paste is 3-4 parts; The additive A is 23.7-40.1 parts; The B component comprises the following raw materials in parts by weight: The isocyanate curing agent is 70-90 parts; The additive B is 10-30 parts; The water-based polycarbonate polyol modified hydroxyl acrylic resin is prepared by the preparation method in any one of claims 1 or 2.

4. The aqueous matte black two-component polyurethane coating according to claim 3, characterized in that The black paste comprises the following components in parts by weight: 18-22 parts of carbon black, 15-25 parts of a water-based dispersant, 3-8 parts of a solvent and 50-60 parts of deionized water; wherein the carbon black is Raven 5000 Ultra II from Boral, the water-based dispersant is DISPERBYK-199 from BYK-Chemie, and the solvent is propylene glycol.

5. The aqueous matte black two-component polyurethane coating according to claim 4, characterized in that The preparation method of the black paste comprises the following steps: adding the solvent into the deionized water under stirring at a speed of 400-600 rpm, dispersing for 3-5 min and stirring uniformly; then adding the water-based dispersant under stirring at a speed of 600-800 rpm, dispersing for 8-10 min and stirring uniformly; then adding the carbon black under stirring at a speed of 800-1000 rpm, dispersing for 8-10 min and stirring uniformly to obtain a mixed solution; and finally grinding the mixed solution in a sand mill with zirconium beads of 1-3 mm for 3-5 times until the fineness is ≤15 um, to obtain the black paste.

6. The aqueous matte black two-component polyurethane coating according to any one of claims 3 to 5, characterized in that The auxiliary A comprises the following components by weight: 5.5-6.0 parts of matting powder, 0.2-0.3 parts of defoaming agent, 0.5-1 parts of base material wetting agent I, 1-2 parts of base material wetting agent II, 0.3-0.5 parts of rheological auxiliary II, 0.2-0.3 parts of drier, 3-5 parts of auxiliary solvent I, 3-5 parts of auxiliary solvent II, 10-20 parts of deionized water; wherein the matting powder is one or both of DKS ACEMATT TS100 and ACEMATT 3300, the defoaming agent is one or both of BYK-093 of BYK-Chemie and Foamex 810 of Wincrete, the base material wetting agent I is Tego KL245 of Wincrete, the base material wetting agent II is one or both of 104E and 104DPM of Air Products, the rheological auxiliary II is one or both of U605 of Wanhua Chemical and RHEOBYK-H 7625 VF of BYK-Chemie, the drier is Borchers LH 10, the auxiliary solvent I is one or both of dipropylene glycol methyl ether and diethylene glycol butyl ether, and the auxiliary solvent II is one or both of dipropylene glycol butyl ether and propylene glycol butyl ether.

7. The aqueous matte black two-component polyurethane coating according to any one of claims 3 to 5, characterized in that The isocyanate curing agent is Aquolin® 269 of Wanhua Chemical, the auxiliary B is auxiliary solvent III, and the auxiliary solvent III is propylene glycol diacetate.

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