Water-based acrylic finish based on core-shell structure design and preparation method thereof

Abstract

The application discloses a water-based acrylic finish based on a core-shell structure design and a preparation method thereof, and belongs to the technical field of acrylic finishes.The water-based acrylic finish comprises a core layer, an intermediate layer, a shell layer, an additive and residual water, and each component comprises the following components in parts by mass: the core layer comprises methyl methacrylate 20-30 parts, butyl acrylate 10-20 parts, hydroxyethyl acrylate 3-7 parts and vinyl triphenyl diphosphonamide 2-4 parts; the intermediate layer comprises caprolactone modified acrylic acid 8-12 parts, styrene 6-10 parts and a microencapsulated repairing agent 4-6 parts; the shell layer comprises fluorine-containing acrylate 10-14 parts, a light inhibitor 0.3-0.7 parts and KH570 modified nano silicon oxide 1-3 parts; and the additive comprises an emulsifier 1-2 parts, potassium persulfate 0.4-0.8 parts and ammonia water; wherein the ammonia water is configured to adjust the pH of the finish to 7-8, the microencapsulated repairing agent uses urea-formaldehyde resin as a wall material and encapsulates an isocyanate compound as a repairing agent; and the microcapsule with urea-formaldehyde resin as the wall material and the isocyanate compound as the core material is innovatively introduced into the core layer, so that the coating is successfully endowed with the intelligent self-repairing capability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of acrylic finish, and particularly relates to a water-based acrylic finish based on a core-shell structure design and a preparation method thereof. BACKGROUND

[0002] The water-based acrylic resin has become one of the most important film-forming substances in the coating industry due to its environmental protection, non-toxicity, good weather resistance, good gloss retention and color retention, and is widely used in the fields of automobiles, buildings, furniture, industrial protection and the like. However, the traditional water-based acrylic coating still has deficiencies in hardness, toughness, chemical resistance and special functionality, and is difficult to meet the increasing demand for high-performance applications.

[0003] In order to overcome these limitations, the core-shell structure emulsion polymerization technology is introduced into the development of the water-based acrylic coating. The technology can effectively coordinate the contradiction between the hardness and toughness of the coating by designing the core layer and shell layer structures with different glass transition temperatures (Tg), however, a single core-shell structure can only improve the performance in one aspect, and it is difficult to simultaneously integrate multiple advanced functions such as long-term flame retardation, self-repair, and the like, and the improvement of the toughness is still insufficient in the extremely low temperature environment.

[0004] On the other hand, the coating inevitably produces micro scratches, micro cracks and other micro damages during service. These damages will become the channels for the invasion of water, oxygen and corrosive ions, resulting in a sharp decline in the protective performance of the coating, and eventually causing the corrosion or aging of the substrate. To solve this problem, the concept of self-repairing coating emerges as the times require. Current researches are mostly focused on achieving the self-repairing function by adding microcapsules in the outer coating, however, the direct application of this technology to the water-based acrylic system faces great challenges: first, the physical blending of the microcapsules will seriously damage the continuity and mechanical properties of the coating, resulting in a decline in the original performance; second, the microcapsules have poor compatibility with the water-based acrylic emulsion, and are prone to aggregation and sedimentation, affecting the storage stability and construction leveling property; finally, simple physical blending cannot achieve precise positioning and efficient utilization of the repair agent, and the repair efficiency is limited. SUMMARY

[0005] In order to overcome some of the problems mentioned in the background above, the present application provides a water-based acrylic finish based on a core-shell structure design and a preparation method thereof, to at least partially solve the above problems.

[0006] According to the technical scheme of the present application, a water-based acrylic finish based on a core-shell structure design is provided, which comprises a water-based acrylic emulsion, and the water-based acrylic emulsion comprises a core layer, an intermediate layer, a shell layer, an additive and a balance of water, and each component comprises, by mass fraction:

[0007] Core layer: methyl methacrylate 20-30 parts, butyl acrylate 10-20 parts, hydroxyethyl acrylate 3-7 parts and vinyl triphenyl diphosphonate 2-4 parts;

[0008] Intermediate layer: caprolactone modified acrylic acid 8-12 parts, styrene 6-10 parts and microencapsulated repair agent 4-6 parts;

[0009] Shell layer: fluorine-containing acrylate 10-14 parts, light inhibitor 0.3-0.7 parts and KH570 modified nano silicon oxide 1-3 parts;

[0010] Auxiliary: emulsifier 1-2 parts, potassium persulfate 0.4-0.8 parts and ammonia;

[0011] Among them, the ammonia is configured to adjust the topcoat PH to 7-8, and the microencapsulated repair agent uses urea-formaldehyde resin as a wall material and isocyanate compound as a repair agent.

[0012] Preferably, the particle size of the microencapsulated repair agent is 1-5 μm, and the emulsifier includes a reactive emulsifier COPS-1.

[0013] On the other hand, the present application also provides a preparation method of water-based acrylic topcoat based on core-shell structure design, comprising the following steps:

[0014] Deionized water, emulsifier and methacrylic acid are added to a reaction vessel, and after warming and stirring, methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonate mixed monomers are emulsified, then warmed, and a solution of potassium persulfate initiator is added dropwise to obtain a core layer emulsion;

[0015] The mixed monomers of caprolactone modified acrylic acid and styrene and the initiator solution are simultaneously added dropwise to the core layer emulsion, and the microencapsulated repair agent is slowly added synchronously, and after the dropwise addition is completed, the reaction is carried out under stirring to obtain an intermediate layer wrapped emulsion;

[0016] The mixed monomers of fluorine-containing acrylate, light inhibitor and KH570 modified nano silicon oxide and the initiator solution and emulsifier are added dropwise to the intermediate layer wrapped emulsion, and after the dropwise addition is completed, a shell layer polymerization emulsion is obtained;

[0017] After the emulsifier is added and reacted, the PH is adjusted to 7-8 by ammonia, and a core-shell structure water-based acrylic emulsion is obtained by filtration;

[0018] The core-shell structure water-based acrylic emulsion is mixed and dispersed with pigments and fillers, thickening agents and defoaming agents to obtain a water-based acrylic topcoat.

[0019] Further, the deionized water, the reactive emulsifier COPS-1 and the methacrylic acid are added into the reaction container, and the temperature is increased to 60-65 DEG C and stirred for 35-45 minutes, the methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphthalene glycol phosphoramide mixed monomer emulsion is added for 30-40 minutes, and then the temperature is increased to 80-85 DEG C, the potassium persulfate initiator solution is added dropwise, the dropwise adding time is 1-2 hours, after the dropwise adding is completed, the reaction is carried out for 2-3 hours, and the core layer emulsion is obtained.

[0020] Further, the caprolactone modified acrylic acid and styrene mixed monomer and the initiator solution are added dropwise into the core layer emulsion at the same time, and the microencapsulated repairing agent is added synchronously, the dropwise adding time is 1-2 hours, after the dropwise adding is completed, the reaction is carried out at 75-85 DEG C for 2-3 hours.

[0021] Further, the fluorine-containing acrylic ester, the light inhibitor and the KH570 modified nano silicon oxide mixed monomer and the initiator solution and the emulsifier are added dropwise into the emulsion wrapped by the intermediate layer, the dropwise adding time is 1-2 hours, after the dropwise adding is completed, the reaction is carried out at 75-85 DEG C for 2-3 hours.

[0022] Further, the shell layer polymerization emulsion is cooled to 45-55 DEG C, the emulsifier is added and reacted for 35-45 minutes, the pH is adjusted to 7-8 by using ammonia water, and the core-shell structure acrylic emulsion is obtained by filtering the material.

[0023] Further, after the core layer mixed monomer emulsion is completed, the temperature is increased to 80-82 DEG C, and the initiator solution is started to be added dropwise, the dropwise adding speed is controlled to be 50%-60% of the total initiator solution amount per hour, and the monomer polymerization is ensured to be uniform.

[0024] Further, the adding speed of the microencapsulated repairing agent is consistent with the dropwise adding speed of the fluorine-containing acrylic ester, the light inhibitor and the KH570 modified nano silicon oxide mixed monomer, and the stirring speed is controlled to be 200-300 r / min, so that the microcapsule is prevented from agglomerating or breaking.

[0025] On the other hand, the application also provides an application of the water-based acrylic finish based on the core-shell structure design, and the water-based acrylic finish based on the core-shell structure design is applied in the fields of new energy automobile battery package shell coating, high-end engineering machinery coating, outdoor steel structure building and facility coating and ocean platform coating.

[0026] Compared with the prior art, the application has the beneficial effects that:

[0027] The present application successfully gives the coating the intelligent self-repairing ability by innovatively introducing the microcapsule with urea-formaldehyde resin as the wall material and isocyanate compound as the core material in the core layer, when the coating produces microcracks due to external stress, the crack tip stress will make the microcapsule break, the released repair agent immediately reacts with the moisture / active groups reserved in the environment or the formula to generate polyurea and other substances, thereby automatically and efficiently filling and healing the cracks;

[0028] The present application perfectly cooperates the high hardness, high flexibility and excellent adhesion of the coating through the unique "rigid core-flexible intermediate layer-functional shell" triple structure design, overcomes the technical contradiction that the traditional coating is difficult to balance the high hardness and high flexibility, and makes the coating maintain excellent adhesion, impact resistance and crack resistance at different temperature environments (especially at low temperature). DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments will be clearly and completely described below, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments; based on the embodiments, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope.

[0030] The present application provides a water-based acrylic finish based on a core-shell structure design, the water-based acrylic finish includes a water-based acrylic emulsion, the water-based acrylic emulsion includes a core layer, an intermediate layer, a shell layer, an additive and a balance of water, each component includes, by mass parts:

[0031] The core layer: methyl methacrylate 20-30 parts, butyl acrylate 10-20 parts, hydroxyethyl acrylate 3-7 parts and vinyl triphenyl diphthalene glycol phosphoramide 2-4 parts;

[0032] The intermediate layer: caprolactone modified acrylic acid 8-12 parts, styrene 6-10 parts and microencapsulated repair agent 4-6 parts;

[0033] The shell layer: fluorine-containing acrylic ester 10-14 parts, light inhibitor 0.3-0.7 parts and KH570 modified nano silicon oxide 1-3 parts;

[0034] The additive: emulsifier 1-2 parts, potassium persulfate 0.4-0.8 parts and ammonia;

[0035] Among them, the ammonia is configured to adjust the finish PH to 7-8, and the microencapsulated repair agent has urea-formaldehyde resin as the wall material and isocyanate compound as the repair agent.

[0036] In further embodiments of the present application, the particle size of the microencapsulated repair agent is 1-5 microns, and the emulsifier includes a reactive emulsifier COPS-1.

[0037] It should be noted that the core layer is combined with monomers with strong rigidity, i.e., methyl methacrylate and butyl acrylate, and a reactive phosphamide flame-retardant monomer is introduced to provide basic mechanical properties and flame-retardant properties for the coating.

[0038] The intermediate layer introduces caprolactone-modified acrylic acid and microencapsulated repair agent to significantly reduce the glass transition temperature and improve low-temperature flexibility, and when the coating is damaged, the microcapsules rupture to release the repair agent, which reacts with moisture in the environment to generate polyurea to repair the cracks.

[0039] The shell layer uses fluorine-containing acrylate to provide long-lasting weather resistance and excellent hydrophobicity and light inhibitors, and adds KH570-modified nano-silicon oxide to improve the hardness, wear resistance and synergistic flame retardation of the coating, and endow the coating with excellent surface properties.

[0040] In another aspect, the embodiment of the present application also provides a preparation method of a water-based acrylic finish based on a core-shell structure design, comprising the following steps:

[0041] Deionized water, emulsifier and methacrylic acid are added to a reaction container, and after warming and stirring, methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonamide mixed monomers are emulsified, and then warmed, and a solution of potassium persulfate initiator is added dropwise to react to obtain a core layer emulsion;

[0042] The mixed monomers of caprolactone-modified acrylic acid and styrene and the initiator solution are added dropwise into the core layer emulsion at the same time, and the microencapsulated repair agent is slowly added synchronously, and after the dropwise addition is completed, the reaction is stirred to obtain an intermediate layer wrapped emulsion;

[0043] The mixed monomers of fluorine-containing acrylate, light inhibitor and KH570-modified nano-silicon oxide and the initiator solution and emulsifier are added dropwise into the intermediate layer wrapped emulsion, and after the dropwise addition is completed, a shell layer polymerization emulsion is obtained after reaction;

[0044] After the emulsifier is added and reacted, the pH is adjusted to 7-8 by adding ammonia water, and a core-shell structure water-based acrylic emulsion is obtained by filtration;

[0045] The core-shell structure water-based acrylic emulsion is mixed and dispersed with pigments and fillers, thickening agents and defoaming agents to obtain a water-based acrylic finish.

[0046] In a further embodiment of the present application, deionized water, reactive emulsifier COPS-1 and methacrylic acid are added to a reaction container, warmed to 60-65°C and stirred for 35-45 minutes, methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonamide mixed monomers are emulsified for 30-40 minutes, and then warmed to 80-85°C, a solution of potassium persulfate initiator is added dropwise, the dropwise addition time is 1-2 hours, and after the dropwise addition is completed, the reaction is carried out for 2-3 hours to obtain a core layer emulsion.

[0047] In a further embodiment of the present embodiment, the caprolactone modified acrylic acid and styrene mixed monomers and initiator solution are simultaneously added dropwise to the core layer emulsion, and the microencapsulated repair agent is added synchronously, the dropwise adding time is 1-2 hours, and after the dropwise adding is completed, the reaction is carried out at 75-85℃ for 2-3 hours.

[0048] In a further embodiment of the present embodiment, the fluorine-containing acrylic ester, light inhibitor and KH570 modified nano silicon oxide mixed monomers and initiator solution and emulsifier are added dropwise to the intermediate layer wrapped emulsion, the dropwise adding time is 1-2 hours, and after the dropwise adding is completed, the reaction is carried out at 75-85℃ for 2-3 hours.

[0049] In a further embodiment of the present embodiment, the shell layer polymerization emulsion is cooled to 45-55℃, the emulsifier is added and reacted for 35-45 minutes, the pH is adjusted to 7-8 by using ammonia water, and the core-shell structure acrylic emulsion is filtered out.

[0050] In a further embodiment of the present embodiment, after the core layer mixed monomer emulsification is completed, the temperature is increased to 80-82℃ to start the dropwise adding of the initiator solution, the dropwise adding speed is controlled to be 50%-60% of the total initiator solution amount per hour, and the monomer polymerization is ensured to be uniform.

[0051] In a further embodiment of the present embodiment, the adding speed of the microencapsulated repair agent is consistent with the dropwise adding speed of the fluorine-containing acrylic ester, light inhibitor and KH570 modified nano silicon oxide mixed monomers, and the stirring speed is controlled to be 200-300r / min to avoid the microcapsule aggregation or rupture.

[0052] It should be noted that: the microencapsulated repair agent is synchronously added in the intermediate layer polymerization stage, the process parameters are optimized to ensure that the microcapsule is intact and uniformly dispersed in the polymer emulsion during the polymerization, the fluorine-containing acrylic ester is introduced as the shell monomer, and the nano silicon oxide is modified by grafting to enhance the durability and functionality of the shell.

[0053] On the other hand, the present embodiment also provides an application of the water-based acrylic finish based on the core-shell structure design, and the water-based acrylic finish based on the core-shell structure design is applied in the fields of new energy automobile battery pack shell coating, high-end engineering machinery coating, outdoor steel structure building and facility coating and offshore platform coating.

[0054] Example 1

[0055] The mass parts of each component are as follows: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphthalyl glycol phosphoramide 3 parts;

[0056] Intermediate layer: caprolactone modified acrylic acid 10 parts, styrene 8 parts and microencapsulated repair agent 5 parts;

[0057] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts and KH570 modified nano-silica 2 parts;

[0058] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0059] The deionized water, reactive emulsifier COPS-1 and methacrylic acid were added to the reaction vessel, and the temperature was raised to 60°C and stirred for 40 minutes. Methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonate mixed monomer emulsion was added and stirred for 35 minutes. Then the temperature was raised to 80°C, and the solution of potassium persulfate initiator was added dropwise. The dropwise addition time was 2 hours, and after the dropwise addition was completed, the reaction was carried out for 3 hours to obtain the core layer emulsion. After the core layer mixed monomers, i.e. methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonate mixed monomer emulsion was completed, the temperature was raised to 80°C and the initiator solution was added dropwise. The dropwise addition rate was controlled to be 50% of the total initiator solution per hour to ensure uniform monomer polymerization.

[0060] The caprolactone modified acrylic acid and styrene mixed monomers and the initiator solution were added dropwise to the core layer emulsion at the same time, and the microencapsulated repair agent was added synchronously. The dropwise addition time was 1.5 hours, and after the dropwise addition was completed, the reaction was carried out at 80°C for 2.5 hours. The addition rate of the microencapsulated repair agent was consistent with the dropwise addition rate of the fluorine-containing acrylate, light inhibitor and KH570 modified nano-silica mixed monomers, and the stirring speed was controlled at 250 r / min to avoid microcapsule agglomeration or rupture.

[0061] The fluorine-containing acrylate, light inhibitor and KH570 modified nano-silica mixed monomers and the initiator solution and emulsifier were added dropwise to the emulsion wrapped by the intermediate layer. The dropwise addition time was 2 hours, and after the dropwise addition was completed, the reaction was carried out at 80°C for 3 hours.

[0062] The shell layer polymerization emulsion was cooled to 50°C, emulsifier was added and reacted for 40 minutes, the pH was adjusted to 8 with ammonia water, and the core-shell structure acrylic emulsion was obtained by filtration.

[0063] Example 2

[0064] The difference between example 1 and example 2 is that the mass parts of each component are as follows: core layer: methyl methacrylate 28 parts, butyl acrylate 12 parts, hydroxyethyl acrylate 6 parts and vinyl triphenyl diphosphonate 3.5 parts;

[0065] Intermediate layer: caprolactone modified acrylic acid 9 parts, styrene 9 parts and microencapsulated repair agent 4.5 parts;

[0066] Shell layer: fluorine-containing acrylate 11 parts, light inhibitor 0.6 parts and KH570 modified nano-silica 2.5 parts;

[0067] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0068] Example 3

[0069] The difference from example 1 is that the mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphosphonamide 3 parts;

[0070] Intermediate layer: caprolactone modified acrylic acid 12 parts, styrene 7 parts and microencapsulated repair agent 5.5 parts;

[0071] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts and KH570 modified nano-silica 2 parts;

[0072] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0073] Example 4

[0074] The difference from example 1 is that the mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphosphonamide 3 parts;

[0075] Intermediate layer: caprolactone modified acrylic acid 10 parts, styrene 8 parts and microencapsulated repair agent 5 parts;

[0076] Shell layer: fluorine-containing acrylate 14 parts, light inhibitor 0.7 parts and KH570 modified nano-silica 3 parts;

[0077] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0078] Example 5

[0079] The difference from example 1 is that the mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphosphonamide 3 parts;

[0080] Intermediate layer: caprolactone modified acrylic acid 6 parts, styrene 9 parts and microencapsulated repair agent 8 parts;

[0081] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts and KH570 modified nano-silica 2 parts;

[0082] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0083] Example 6

[0084] The difference from Example 1 is that the mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphosphonate 3 parts;

[0085] Intermediate layer: caprolactone modified acrylic acid 10 parts, styrene 8 parts and microencapsulated repair agent 5 parts;

[0086] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts and KH570 modified nano silicon dioxide 2 parts;

[0087] Auxiliary: emulsifier 1.8 parts, potassium persulfate 0.5 parts and deionized water 100 parts.

[0088] Comparative Example 1

[0089] The mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, hydroxyethyl acrylate 5 parts and vinyl triphenyl diphosphonate 3 parts;

[0090] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts and KH570 modified nano silicon dioxide 2 parts;

[0091] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts and deionized water 100 parts.

[0092] Deionized water, reactive emulsifier COPS-1 and methacrylic acid were added to the reaction vessel, heated to 60°C and stirred for 40 minutes, then methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonate mixed monomer emulsion was added and emulsified for 35 minutes, then the temperature was raised to 80°C, and the initiator solution was added dropwise, the dropwise addition time was 2 hours, after the dropwise addition was completed, the reaction was carried out at 80°C for 3 hours, to obtain the core layer emulsion. After the core layer mixed monomers, i.e. methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and vinyl triphenyl diphosphonate mixed monomers were emulsified, the temperature was raised to 80°C and the initiator solution was added dropwise, the dropwise addition rate was controlled to be 50% of the total initiator solution amount per hour, to ensure uniform monomer polymerization.

[0093] The fluorine-containing acrylate, light inhibitor and KH570 modified nano silicon dioxide mixed monomers and initiator solution and emulsifier were added dropwise to the emulsion, the dropwise addition time was 2 hours, and after the dropwise addition was completed, the reaction was carried out at 80°C for 3 hours.

[0094] The shell layer polymerization emulsion was cooled to 50°C, emulsifier was added and reacted for 40 minutes, the pH was adjusted to 8 with ammonia water, and the core-shell structure acrylic emulsion was filtered out.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that the mass parts of each component are respectively: core layer: methyl methacrylate 25 parts, butyl acrylate 15 parts, and hydroxyethyl acrylate 5 parts;

[0097] Intermediate layer: caprolactone-modified acrylic acid 10 parts, styrene 8 parts, and microencapsulated repair agent 5 parts;

[0098] Shell layer: fluorine-containing acrylate 12 parts, light inhibitor 0.5 parts, and KH570-modified nano-silicon oxide 2 parts;

[0099] Auxiliary: emulsifier 1.5 parts, potassium persulfate 0.6 parts, and deionized water 100 parts.

[0100] The water-based acrylic emulsion prepared in the above Examples 1-6 and Comparative Examples 1 and 2 is used to prepare a water-based acrylic finish. The preparation method of the water-based acrylic is as follows:

[0101] In the dispersion cylinder, 3 g of deionized water, 0.8 g of Disperbyk®-190 dispersant, 0.2 g of Hydropalat® 436 wetting agent, and 0.3 g of BYK®-024 defoamer are sequentially added; stirring at a speed of 300-500 rpm for 5 minutes to ensure uniform mixing.

[0102] Slowly add 12 g of titanium white powder R-706, taking care not to generate dust, and after adding, increase the speed to 800-1000 rpm and stir for 10 minutes to ensure complete wetting of the powder, resulting in a thick slurry without dry powder.

[0103] Then increase the speed to 1500-2000 rpm and high-speed disperse for 20-30 minutes; use a doctor blade fineness gauge to detect the fineness of the slurry, and stop dispersing when the fineness is ≤15 μm; reduce the speed, add 0.1 g of Acticide® MBS preservative, and stir for another 5 minutes to obtain a uniform and fine white paste, which is used as the first color paste.

[0104] In the paint conditioning cylinder, add 70 g of the water-based acrylic emulsion prepared in the examples or comparative examples, and under low-speed stirring at 300-500 rpm, first slowly add 1.5 g of Texanol™ film-forming aid and stir for 10 minutes to ensure complete fusion, then sequentially add 0.2 g of BYK®-346 leveling agent, 0.5 g of Raybo® 60 corrosion inhibitor, 0.2 g of BYK®-024 defoamer, and 5 g of deionized water to obtain an emulsion mixture.

[0105] Slowly add the first color paste into the emulsion mixture, continue stirring for 15-20 minutes after adding, ensure that the system is completely uniform, pre-dilute 0.4g of UH-752 thickening agent with part of deionized water, then slowly add it into the paint under low speed stirring, avoid local thickening too fast, slowly add ammonia water, adjust the pH value of the system to 8.0-9.0, continue stirring until the system is uniform, stop stirring and then filter the paint with a 100-200 mesh filter screen to remove possible gel particles or impurities, package and store, and mature for 24 hours.

[0106] The topcoats prepared from the products obtained in Examples 1-6 and Comparative Examples 1 and 2 were respectively subjected to self-repairing efficiency, pencil hardness, low-temperature flexibility, flame-retardant grade and weather resistance detection, wherein the self-repairing efficiency was detected by GB / T 37267-2018 Self-repairing coatings, the pencil hardness was detected by GB / T 6739-2022 Paint and varnish - Determination of film hardness by the pencil method, the low-temperature flexibility was detected by GB / T 6742-2021 Paint and varnish - Bending test (cylinder axis), the flame-retardant grade was detected by UL 94-2024 Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, and the weather resistance was detected by GB / T 1865-2009 Paint and varnish - Artificial weathering and artificial radiation exposure (filtered xenon arc radiation), and the detection results are shown in Table 1.

[0107] Table 1

[0108]

[0109] As can be seen from the above, the examples of the present application all meet the requirements of self-repairing efficiency of 85%-95%, pencil hardness of H or above, no low-temperature cracking at-30℃, flame-retardant UL94 V-0 grade, weather resistance with gloss retention rate of 80% or above after 1000h, completely meeting the requirements of harsh environments such as high temperature and high humidity, strong corrosion, etc., and the performance can be targetedly optimized by adjusting the key components, such as the upper limit of microcapsules in Example 5 → highest self-repairing; the upper limit of fluorine-containing monomers in Example 4 → best weathering performance.

[0110] Comparative Example 1 lacks microcapsules, and the self-repairing efficiency drops to 5%, directly proving that microencapsulated repair agent is a necessary condition for realizing self-repairing function, and Comparative Example 2 lacks reactive flame-retardant monomers, and the flame-retardant grade decreases from V-0 to V-2, proving the key role of reactive phosphamide monomers in long-term flame retardation, and the effect of additive flame retardants in the prior art cannot replace it.

[0111] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A waterborne acrylic topcoat based on core-shell structure design, characterized in that, The water-based acrylic finish includes a water-based acrylic emulsion, which includes a core layer, an intermediate layer, a shell layer, an additive, and a balance of water, each component includes, by mass parts: Core layer: methyl methacrylate 20-30 parts, butyl acrylate 10-20 parts, hydroxyethyl acrylate 3-7 parts, and vinyl triphenyl diphosphine glycol phosphoramide 2-4 parts; Intermediate layer: caprolactone modified acrylic acid 8-12 parts, styrene 6-10 parts, and microencapsulated repair agent 4-6 parts; Shell layer: fluorine-containing acrylic ester 10-14 parts, light inhibitor 0.3-0.7 parts, and KH570 modified nano silicon oxide 1-3 parts; Additive: emulsifier 1-2 parts, potassium persulfate 0.4-0.8 parts, and ammonia; Among them, the ammonia is configured to adjust the finish PH to 7-8, the microencapsulated repair agent uses urea-formaldehyde resin as a wall material to wrap isocyanate compounds as a repair agent.

2. The water-based acrylic finish based on core-shell structure design according to claim 1, characterized in that, The particle size of the microencapsulated repair agent is 1-5 μm, and the emulsifier includes a reactive emulsifier COPS-1.

3. A process for the preparation of a water-based acrylic finish based on the core-shell structure design according to any one of claims 1-2, characterized in that, The method includes the following steps: Deionized water, emulsifier, and methacrylic acid are added to a reaction vessel, and after warming and stirring, methyl methacrylate, butyl acrylate, hydroxyethyl acrylate, and vinyl triphenyl diphosphine glycol phosphoramide mixed monomers are emulsified, then warmed, and a solution of potassium persulfate initiator is added dropwise to react to obtain a core layer emulsion; To the core layer emulsion, caprolactone modified acrylic acid and styrene mixed monomers and an initiator solution are added dropwise at the same time, and the microencapsulated repair agent is slowly added synchronously, and after the dropwise addition is completed, the intermediate layer wrapped emulsion is obtained by stirring and reacting; To the intermediate layer wrapped emulsion, fluorine-containing acrylic ester, light inhibitor, and KH570 modified nano silicon oxide mixed monomers, an initiator solution, and an emulsifier are added dropwise, and after the dropwise addition is completed, the shell layer polymerization emulsion is obtained; After adding the emulsifier and reacting, the PH is adjusted to 7-8 by ammonia, and the core-shell structure water-based acrylic emulsion is obtained by filtering; The core-shell structure water-based acrylic emulsion is mixed and dispersed with pigments and fillers, thickening agents, and defoaming agents to obtain a water-based acrylic finish.

4. The method for preparing water-based acrylic finish based on core-shell structure design according to claim 3, characterized in that, Deionized water, reactive emulsifier COPS-1, and methacrylic acid are added to a reaction vessel, warmed to 60-65°C, and stirred for 35-45 minutes, methyl methacrylate, butyl acrylate, hydroxyethyl acrylate, and vinyl triphenyl diphosphine glycol phosphoramide mixed monomers are emulsified for 30-40 minutes, then warmed to 80-85°C, a solution of potassium persulfate initiator is added dropwise, the dropwise addition time is 1-2 hours, after the dropwise addition is completed, the core layer emulsion is obtained by reacting for 2-3 hours.

5. The method for preparing water-based acrylic finish based on core-shell structure design according to claim 3, characterized in that, To the core layer emulsion, caprolactone modified acrylic acid and styrene mixed monomers and an initiator solution are added dropwise at the same time, and the microencapsulated repair agent is slowly added synchronously, and after the dropwise addition is completed, the intermediate layer wrapped emulsion is obtained by stirring and reacting; 6. The method for preparing water-based acrylic finish based on core-shell structure design according to claim 3, characterized in that, To the intermediate layer wrapped emulsion, fluorine-containing acrylic ester, light inhibitor, and KH570 modified nano silicon oxide mixed monomers, an initiator solution, and an emulsifier are added dropwise, the dropwise addition time is 1-2 hours, and after the dropwise addition is completed, the shell layer polymerization emulsion is obtained by warming and reacting at 75-85°C for 2-3 hours.

7. The method for preparing water-based acrylic finish based on core-shell structure design according to claim 3, characterized in that, The shell layer polymerization emulsion is cooled to 45-55 DEG C, emulsifier is added and reacted for 35-45 minutes, ammonia water is used to adjust the pH to 7-8, and the product is filtered to obtain a core-shell structure acrylic emulsion.

8. The method for preparing water-based acrylic finish based on core-shell structure design according to claim 3, characterized in that, After the core layer mixed monomers are emulsified, the temperature is raised to 80-82 DEG C to start dropping the initiator solution, the dropping rate is controlled to be 50%-60% of the total initiator solution amount per hour, and the monomer polymerization is ensured to be uniform.

9. The method for preparing a waterborne acrylic topcoat based on a core-shell structure design according to claim 3, characterized in that, The adding rate of the microencapsulated repairing agent is consistent with the dropping rate of the mixed monomers of the fluorine-containing acrylic ester, the light inhibitor and the KH570 modified nano silicon oxide, and the stirring speed is controlled to be 200-300 r / min to avoid microcapsule agglomeration or rupture.

10. Use of a waterborne acrylic topcoat based on core-shell design, characterized in that, The application of the water-based acrylic finish based on the core-shell structure design according to any one of claims 1-2 in the fields of new energy automobile battery pack shell coating, high-end engineering machinery coating, outdoor steel structure building and facility coating and ocean platform coating.

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