A hydrophilic structural light-cured coating and its preparation method and application

Abstract

The present application belongs to the field of photocuring coating, and particularly relates to a photocuring coating containing hydrophilic structure, and a preparation method and application thereof. The photocuring coating containing hydrophilic structure contains modified acrylate resin, monofunctional diluent, multifunctional diluent, nanoparticles, photoinitiator, and optional solvent and auxiliary agent, with a mass ratio of 1:(0.125-0.8):(0.125-0.8):(0.025-0.4):(0.025-0.2):(0-1.6):(0-0.04); the modified acrylate resin is a double bond-terminated acrylate resin obtained by reacting diisocyanate and dihydric alcohol I with hydroxyl-terminated acrylate; the modified acrylate resin has a structure shown in formula (1); and the nanoparticles are nanosilica sol and / or mesoporous silica. The key of the present application lies in introducing modified acrylate resin with specific structure and nanoparticles, so that the obtained photocuring coating has good hydrophilic property, so that when water vapor condensation occurs, water vapor can form a transparent water film on the surface of the coating, without affecting the transparency and achieving good anti-fog effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photocuring coating, and particularly relates to a photocuring coating containing a hydrophilic structure, a preparation method and application thereof. BACKGROUND

[0002] The ultraviolet photocuring coating is an environmental protection and energy saving type coating developed in the 1960s, which can be quickly cured under the irradiation of ultraviolet light. The photocuring coating not only has a fast curing speed, but also saves energy compared with the heat curing coating. The photocuring coating is not only widely used in metal, leather, wood, plastic and other materials, but also successfully applied in the fields of optical fiber, printed circuit board, electronic device packaging and the like.

[0003] The water contact angle on the surface of transparent materials such as glass, plastic and film is generally above 40°. When there is a temperature difference between the inner and outer surfaces of the transparent material, the water vapor pressure on the surface with lower temperature is lower than the vapor pressure in the surrounding environment. The air humidity or vapor will condense on the surface to form fog, and even small water droplets. When the surface of the transparent material appears fogging phenomenon, the transparent material becomes opaque, which affects the visual effect. The fogging phenomenon seriously affects the transparency, and the precipitation of small water droplets causes the light to be diffusely reflected when passing through, which significantly reduces the light transmittance of the transparent material. This brings many inconveniences to people's life, for example, the fogging of glasses will make the person's field of vision blurred; the fogging of the windshield and rearview mirror of the car will bring safety hazards to traffic; the fogging of the camera ball cover will make the monitoring image blurred and distorted; the fogging of the surface of the solar energy absorbing part will seriously reduce the utilization rate of solar energy; the fogging of the surface of the agricultural plastic film will also seriously reduce the light transmittance of the film and affect the growth of crops. The photocuring coating in the prior art mostly uses oligomer resin as polyurethane acrylate, which has poor hydrophilicity and basically cannot achieve the effect of anti-fogging. SUMMARY

[0004] One of the purposes of the present application is to propose a photocuring coating containing a hydrophilic structure in view of the defects that the polyurethane acrylate in the prior art has poor hydrophilicity and cannot achieve the effect of anti-fogging.

[0005] Specifically, the hydrophilic structure-containing photocuring coating contains modified acrylate resin, monofunctional diluent, multifunctional diluent, nanoparticles, photoinitiator, and optional solvent and auxiliary agent in a mass ratio of 1:(0.125-0.8):(0.125-0.8):(0.025-0.4):(0.025-0.2):(0-1.6):(0-0.04); the modified acrylate resin is a double-bond-terminated acrylate resin obtained by reacting diisocyanate and dihydric alcohol I with terminal hydroxyl acrylate; the modified acrylate resin has a structure shown in formula (1); and the nanoparticles are inorganic nanosilica sol and / or mesoporous silica.

[0006]

[0007] In formula (1), R1 is a group derived from dihydric alcohol I, R2 is a group derived from diisocyanate, R3 is a group derived from hydrophilic oligomeric dihydric alcohol and having at least one hydroxyl group in the side chain, and n is an integer of 1-7.

[0008] The second object of the present application is to provide a preparation method of the above-mentioned hydrophilic structure-containing photocuring coating, which comprises uniformly mixing and stirring the modified acrylate resin, monofunctional diluent, multifunctional diluent, nanoparticles, photoinitiator, and optional solvent and auxiliary agent, and then discharging under light protection to obtain the hydrophilic structure-containing photocuring coating.

[0009] The third object of the present application is to provide an anti-fog coating prepared from the above-mentioned hydrophilic structure-containing photocuring coating.

[0010] The fourth object of the present application is to provide a preparation method of the anti-fog coating, which comprises coating the above-mentioned hydrophilic structure-containing photocuring coating on a substrate, and obtaining the anti-fog coating after curing.

[0011] The key of the present application is to synergistically combine the modified acrylate resin having a specific structure and nanoparticles with monofunctional diluent, multifunctional diluent, photoinitiator, and optional solvent and auxiliary agent in a certain proportion, so that the obtained photocuring coating has good anti-fog effect. This is mainly because the multiple hydroxyl groups in the molecular chain of the modified acrylate resin can significantly improve the hydrophilic property of the photocuring coating and reduce the water contact angle of the coating surface formed after curing of the photocuring coating, and the introduction of nanoparticles enables the formation of micro-nano structure on the surface of the cured coating, so that when water vapor condenses, the water vapor will first penetrate into the micro-nano structure and then spread, i.e., a transparent water film will be formed on the surface of the coating, which does not affect the transparency and thus achieves the purpose of anti-fog. The hydrophilic structure-containing photocuring coating provided by the present application has good anti-fog effect and good adhesion and hardness, the preparation process is simple, and it can be suitable for industrial production. DETAILED DESCRIPTION

[0012] The hydrophilic structure-containing photocurable coating provided by the present application contains a modified acrylate resin, a monofunctional diluent, a multifunctional diluent, nanoparticles, a photoinitiator, and optionally a solvent and an additive, in a mass ratio of 1:(0.125-0.8):(0.125-0.8):(0.025-0.4):(0.025-0.2):(0-1.6):(0-0.04). The mass ratio of the modified acrylate resin to the monofunctional diluent is 1:(0.125-0.8), such as 1:0.125, 1:0.15, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, or any value therebetween. The mass ratio of the modified acrylate resin to the multifunctional diluent is 1:(0.125-0.8), such as 1:0.125, 1:0.15, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, or any value therebetween. The mass ratio of the modified acrylate resin to the nanoparticles is 1:(0.025-0.4), such as 1:0.025, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, or any value therebetween. The mass ratio of the modified acrylate resin to the photoinitiator is 1:(0.025-0.2), such as 1:0.025, 1:0.05, 1:0.1, 1:0.15, 1:0.2, or any value therebetween. The mass ratio of the modified acrylate resin to the solvent is 1:(0-1.6), such as 1:0, 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, or any value therebetween. The mass ratio of the modified acrylate resin to the additive is 1:(0-0.04), such as 1:0, 1:0.01, 1:0.02, 1:0.03, 1:0.04, or any value therebetween.

[0013] In the present application, the modified acrylate resin has a structure represented by formula (1);

[0014]

[0015] In formula (1), R1 is a group derived from diol I, R2 is a group derived from diisocyanate, R3 is a group derived from a hydrophilic oligomer diol and having at least one hydroxyl group in the side chain, and n is an integer of 1-7, such as 1, 2, 3, 4, 5, 6, 7, etc.

[0016] In the present application, the content of the modified acrylate resin is preferably 25-40 parts by weight, such as 25, 28, 30, 32, 35, 38, 40 parts by weight or any value therebetween, based on the total weight of the hydrophilic structure-containing photocurable coating; the content of the monofunctional diluent is preferably 5-20 parts by weight, such as 5, 8, 10, 12, 15, 15, 20 parts by weight or any value therebetween; the content of the multifunctional diluent is preferably 5-20 parts by weight, such as 5, 8, 10, 12, 15, 15, 20 parts by weight or any value therebetween; the content of the nanoparticles is preferably 1-10 parts by weight, such as 1, 3, 5, 7.5, 10 or any value therebetween; the content of the photoinitiator is preferably 1-5 parts by weight, such as 1, 2, 3, 4, 5 or any value therebetween; the content of the solvent is preferably 20-40 parts by weight, such as 20, 25, 30, 35, 40 parts by weight or any value therebetween; the content of the auxiliary agent is preferably 0-1 parts by weight, such as 0, 0.2, 0.4, 0.6, 0.8, 1 parts by weight or any value therebetween. Specifically, the auxiliary agent can include a leveling agent and / or a foaming agent. Among them, the content of the leveling agent is preferably 0.1-0.5 parts by weight, such as 0.1, 0.2, 0.3, 0.4, 0.5 parts by weight or any value therebetween; the content of the foaming agent is preferably 0.1-0.5 parts by weight, such as 0.1, 0.2, 0.3, 0.4, 0.5 parts by weight or any value therebetween.

[0017] In the present application, the viscosity of the modified acrylate resin at 25°C is preferably 5000-35000 cps, more preferably 8000-25000 cps, such as 8000 cps, 10000 cps, 12000 cps, 15000 cps, 20000 cps, 22000 cps, 25000 cps or any value therebetween.

[0018] In the present application, the use of monofunctional diluent and multifunctional diluent together is beneficial to improve the film uniformity and control the crosslinking density, on the one hand, it can improve the adhesion and hardness of the photocurable coating, on the other hand, it can form a uniform crosslinking network structure with the modified acrylate resin, and synergistically improve the anti-fog effect of the photocurable coating. Specific examples of the monofunctional diluent include, but are not limited to, at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, ethoxyethyl acrylate, isooctyl acrylate, 4-hydroxy cyclohexyl methacrylate, tetrahydrofurfuryl acrylate and isobornyl acrylate.

[0019] In the present application, the functionality of the multi-functional diluent is preferably 2 to 6, such as 2, 3, 4, 5, 6, etc. Specific examples of the multi-functional diluent include, but are not limited to, at least one of dipropylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, methyl etherified propoxylated pentaerythritol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0020] The nanoparticles are nano-silica sol and / or mesoporous silica. The average particle size of the nano-silica sol is preferably 1 to 100 nm, such as 1 nm, 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, or any value therebetween. Among them, the term "nano-silica" refers to nanoparticles that only include silica or core-shell structure nanoparticles that have a silica core and a shell that protects the silica. The mesoporous silica is preferably spherical, and the average particle size thereof is preferably 50 to 150 nm, such as 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, or any value therebetween.

[0021] In the present application, the photoinitiator can be an existing compound that can generate free radicals under the irradiation of visible light or ultraviolet light to initiate the polymerization of monomers. From the perspective of raw material availability, the photoinitiator is preferably at least one of Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), Irgacure 369 (2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone), Irgacure 907 (2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone), Irgacure 1173 (2-hydroxy-2-methyl-1-phenylpropanone), Irgacure 2959 (2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone), TPO (2,4,6-trimethylbenzoyl-diphenyl phosphine oxide), and TPO-L (2,4,6-trimethylbenzoyl phenyl phosphonic acid ethyl ester).

[0022] In the present application, the solvent can be exemplarily selected from at least one of ethanol, isopropyl alcohol, n-butyl alcohol, propylene glycol methyl ether acetate, tetrahydrofuran, toluene, propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate, cyclopentanone, butyl acetate, methyl isobutyl ketone, n-butanone, 4-methyl-2-pentanone, cyclohexanone, 2-heptanone, gamma-butyrolactone, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, butyrolactone, dimethylformamide, and dimethylacetamide. The solvent serves as an inert liquid medium, and its addition can make the various raw materials added in the preparation of the hydrophilic structure photocuring coating more uniformly mixed.

[0023] In the present application, the leveling agent can be various substances known to improve the leveling performance of the coating, and can be exemplarily selected from at least one of BYK307, BYK333, BYK358, BYK361, BYK366 of BYK company, and EFKA3600, EFKA3883, and EFKA3886 of Evonik company.

[0024] In the present application, the defoaming agent can be various substances known to eliminate or reduce the generation of bubbles in the coating, and can be exemplarily selected from at least one of BYK020, BKY054, BYK352, BYK354, BYK357, BKY1790, and BKY1794 of BYK company.

[0025] In the present application, the modified acrylate resin is a double bond-terminated acrylate resin obtained by reacting diisocyanate and diol I with a hydroxyl-terminated acrylate, and can be specifically prepared according to a method comprising the following steps:

[0026] S1. Diisocyanate and diol I are subjected to an addition reaction in the presence of a polymerization inhibitor and an initiator to obtain an isocyanate double-terminated polyurethane prepolymer;

[0027] S2. The isocyanate double-terminated polyurethane prepolymer obtained in step S1 is subjected to a capping reaction with a hydroxyl-terminated acrylate to obtain a double bond-terminated modified acrylate resin.

[0028] In the preparation process of the modified acrylate resin described above, in step S1, the conditions of the addition reaction include a temperature preferably 70-120°C, such as 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any value therebetween; and a time preferably 3-6h, such as 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any value therebetween.

[0029] In the preparation process of the modified acrylate resin, in step S2, the conditions of the end-capping reaction include a temperature of preferably 90-140°C, such as 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or any value therebetween; and a time of preferably 2-8h, such as 2h, 3h, 4h, 5h, 6h, 7h, 8h, or any value therebetween.

[0030] In the preparation process of the modified acrylate resin, in step S2, the end-capping reaction can be carried out in the following manner: under an inert atmosphere, the temperature is controlled at 90-140°C, the isocyanate double-end-capped polyurethane prepolymer obtained in step S1 is mixed with the terminal hydroxyl acrylate and stirred for 2-8h, and the content of NCO groups in the reaction system is detected every 0.5-1.5h during the reaction, and the reaction is ended when the NCO mass percentage content is ≤0.05%, i.e., the molecular weight terminal isocyanate groups are substantially completely, the temperature is lowered, and the product is discharged, to obtain the modified acrylate resin. The amount of the terminal hydroxyl acrylate used is the total mass when the NCO groups in the reaction system are substantially completely reacted. The term "substantially completely reacted" does not mean absolute complete reaction, but only that the NCO mass percentage content is reduced to 0.05%. Specifically, the terminal hydroxyl acrylate can be added at one time or in steps.

[0031] In the preparation process of the modified acrylate resin, since the isocyanate is sensitive to moisture, in order to enable the reaction of the isocyanate with the dihydric alcohol I and the terminal hydroxyl acrylate to proceed smoothly, the reaction vessel and the reaction raw materials need to be treated for water removal before the reaction is charged, and the reaction system is placed under an inert atmosphere. The way to treat the reaction vessel for water removal is usually to dry the reaction vessel, specifically by drying the reaction vessel at 130-150°C for 2-4h. The way to treat the reaction raw materials for water removal is usually to treat the reaction raw materials by heating and vacuumizing for water removal, freeze-drying, molecular sieve water removal, glove box gas exchange, etc. The way to place the reaction system under an inert atmosphere is usually to introduce a chemical inert gas into the reaction vessel, vacuumize, etc. to drive out air and fill in inert gas, so that the reaction system can be kept under an inert atmosphere. The chemical inert gas can be nitrogen or argon, preferably nitrogen.

[0032] In the present application, the molar ratio of the diisocyanate and the diol I is preferably (1.1-1.3): 1. The molar content of the diisocyanate is preferably 1.1-1.3 mol, such as 1.1 mol, 1.15 mol, 1.2 mol, 1.25 mol, 1.3 mol, or any value therebetween, based on 1 mol of the molar content of the diol I. Specific examples of the diisocyanate include, but are not limited to, toluene diisocyanate, norbornane diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate, 4,4-dicyclohexylhexamethylene diisocyanate, pentamethylene diisocyanate, and / or hexamethylene diisocyanate, more preferably pentamethylene diisocyanate and hexamethylene diisocyanate. The diol I is preferably a polyester diol, which can be at least one of polyethylene adipate, polybutylene adipate, and polycaprolactone diol. The number average molecular weight of the diol I is preferably 400-2000 g / mol, such as 400 g / mol, 600 g / mol, 800 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, or any value therebetween.

[0033] In the present application, the amount of the polymerization inhibitor is preferably 0.02-0.04 wt% of the total mass of the reaction raw materials, such as 0.02 wt%, 0.022 wt%, 0.025 wt%, 0.028 wt%, 0.03 wt%, 0.032 wt%, 0.035 wt%, 0.038 wt%, 0.04 wt%, or any value therebetween. The reaction raw materials include the diisocyanate, the diol I, and the hydroxyl-terminated acrylate. Specific examples of the polymerization inhibitor include, but are not limited to, at least one of hydroquinone, p-methoxyphenol, p-hydroxyanisole, o-methylhydroquinone, and 2,6-di-tert-butyl-4-methylphenol.

[0034] In the present application, the amount of the initiator is preferably 0.1-0.5 wt% of the total mass of the reaction raw materials, such as 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, or any value therebetween. The reaction raw materials include the diisocyanate, the diol I, and the hydroxyl-terminated acrylate. The initiator is preferably an organic tin compound and / or an organic bismuth compound. Specifically, the organic tin compound is preferably at least one of stannous octoate, trimethyltin chloride, dibutyltin dilaurate, dibutyltin dichloride, and methyltin trichloride. The organic bismuth compound is preferably bismuth iso-octoate and / or bismuth carboxylate.

[0035] In the present application, the terminal hydroxyl acrylate is preferably obtained by dehydrating condensation reaction of a hydrophilic oligomer diol with structure shown in formula (2) and acrylic acid in the presence of iodine, and then purification. The dehydrating condensation reaction can be carried out by boiling the hydrophilic oligomer diol, acrylic acid and iodine for 4-8 hours.

[0036]

[0037] In formula (2), R4 is C1-C6 alkylene and the side chain includes at least one hydroxyl group, R5 is C1-C6 alkylene, and m is an integer of 1-7. The specific examples of C1-C6 alkylene include, but are not limited to, at least one of methylene, ethylene, n-propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene, n-pentylene, iso-pentylene, tert-pentylene, neopentylene and n-hexylene. m can be an integer of 1-7, such as 1, 2, 5, 7, etc.

[0038] In the preparation of the terminal hydroxyl acrylate, the purification method can be adding NaCl aqueous solution to the obtained reaction mixture, cooling, then extracting the reaction product with dichloromethane, washing the organic solution with Na2S2O3 aqueous solution, removing the upper aqueous solution, adding appropriate amount of MgSO4 for drying, distilling the product under vacuum, and finally obtaining the terminal hydroxyl acrylate.

[0039] In the present application, the molar ratio of acrylic acid, hydrophilic oligomer diol and iodine is preferably 1:(8-12):(0.01-0.05). The molar content of the hydrophilic oligomer diol is preferably 8-12 mol, such as 8 mol, 9 mol, 10 mol, 11 mol, 12 mol or any value therebetween, based on 1 mol of the molar content of acrylic acid; the molar content of iodine is preferably 0.01-0.05 mol, such as 0.01 mol, 0.015 mol, 0.02 mol, 0.025 mol, 0.03 mol, 0.035 mol, 0.04 mol, 0.045 mol, 0.05 mol or any value therebetween.

[0040] In the present application, the hydroxyl value of the hydrophilic oligomer diol is preferably 120-280 mg KOH / g, such as 120, 150, 180, 200, 220, 250, 280 mg KOH / g or any value therebetween.

[0041] In the present application, the number average molecular weight of the hydrophilic oligomer diol is preferably 300-1500 g / mol, such as 300 g / mol, 500 g / mol, 800 g / mol, 1000 g / mol, 1300 g / mol, 1500 g / mol, or any value therebetween.

[0042] In the present application, the hydrophilic oligomer diol is preferably obtained by subjecting a diacid having the structure shown in formula (3) and a diol II having the structure shown in formula (4) to a polycondensation reaction in the presence of a catalyst. In a specific embodiment, the polycondensation reaction can be performed by heating the diacid, part of the diol II, and the catalyst to 60-80°C under inert gas protection, stirring for 1-5 h, controlling the top temperature of the condenser to be lower than 100°C during the heating process; every 0.5-1 h, the reaction system is vacuumed for about 3-8 min to remove small molecular byproducts, so that the reaction is balanced until there is no significant change in the weight of the reaction system (the mass of the extracted small molecules basically no longer increases); the remaining diol II is added and stirring is continued for 0.5-2 h, then the temperature is raised to 130-180°C and vacuumed to a vacuum degree of ≥0.095 MPa, and the reaction is continued for 0.5-1 h, and the hydroxyl value is tested to be 120-280 mg KOH / g, thereby obtaining the hydrophilic oligomer diol.

[0043] HO-R5-OH formula (4)

[0044] In formula (3) and formula (4), R4 is a C1-C6 alkylene group and the side chain includes at least one hydroxyl group, R5 is a C1-C6 alkylene group, and m is an integer of 1-7. Specific examples of the C1-C6 alkylene group include, but are not limited to, at least one of methylene, ethylene, n-propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene, n-pentylene, iso-pentylene, tert-pentylene, neopentylene, and n-hexylene. m is an integer of 1-7, such as 1, 2, 5, 7, etc.

[0045] In the present application, the molar ratio of the diacid to the diol II is preferably 1:(1.5-1.8). Based on 1 mol of the molar content of the diacid, the molar content of the diol II is preferably 1.5-1.8 mol, such as 1.5 mol, 1.6 mol, 1.7 mol, 1.8 mol, or any value therebetween.

[0046] In the present application, the amount of the catalyst is preferably 0.2-1 wt% of the total mass of the reaction raw materials, i.e. the amount of the catalyst is 0.2-1 wt% of the total mass of the dibasic acid and the dihydric alcohol II, such as 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt% or any value therebetween.

[0047] In the present application, the dibasic acid is preferably a compound having carboxyl groups at both ends of the molecular chain and at least one hydroxyl group in the side chain, and specific examples thereof include, but are not limited to, at least one of aminodiacetic acid, tartaric acid, 2-hydroxybutanedioic acid, 3-hydroxypentanedioic acid, 2-hydroxyhexanedioic acid and 3-hydroxyoctanedioic acid.

[0048] In the present application, specific examples of the dihydric alcohol II include, but are not limited to, at least one of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and neopentyl glycol.

[0049] In the present application, the catalyst can be selected from at least one of sodium bisulfate, p-toluenesulfonic acid, concentrated sulfuric acid and concentrated hydrochloric acid.

[0050] In the present application, the preparation method of the hydrophilic structure-containing photocurable coating includes uniformly mixing and stirring the modified acrylate resin, the monofunctional diluent, the multifunctional diluent, the photoinitiator and the optional auxiliary agent, and then discharging the mixture in the dark to obtain the hydrophilic structure-containing photocurable coating. In a specific embodiment, the preparation method can include the following steps: adding the modified acrylate resin, the monofunctional diluent and the multifunctional diluent into a double-planetary-mixing power reaction kettle and stirring for 1-3 h, then adding the solvent, the nanoparticles, the photoinitiator, the leveling agent and the defoaming agent and stirring for 1-2 h, and then vacuum degassing, discharging and sealing packaging. In addition, the whole preparation and stirring process needs to be strictly avoided in the white light.

[0051] The anti-fog coating provided by the present application is prepared by using the above-mentioned hydrophilic structure-containing photocurable coating.

[0052] The method for preparing the anti-fog coating comprises coating a hydrophilic structure photocuring coating on a substrate, and obtaining the anti-fog coating after curing. Preferably, the substrate coated with the coating is pre-baked before curing. The pre-baking temperature can be 60-100°C, such as 60°C, 70°C, 80°C, 90°C, 100°C or any value between them; the time can be 5-20 min, such as 5 min, 8 min, 10 min, 12 min, 15 min, 18 min, 20 min or any value between them. The thickness of the anti-fog coating is preferably 5-35 μm, such as 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm or any value between them. The coating with the thickness can achieve better anti-fog effect.

[0053] The application will be described in detail below through specific examples.

[0054] In the following examples and comparative examples, the parts of the raw materials refer to weight parts.

[0055] The raw materials involved in the following examples and comparative examples: nanometer silica sol, purchased from Nalco Chemical Company, USA, brand NALCO1115, average particle size 4 nm; spherical mesoporous silica, purchased from Nanjing Xianfeng Nanometer Material Technology Co., Ltd., brand 104437, average particle size 120 nm; spherical mesoporous silica, purchased from Nanjing Xianfeng Nanometer Material Technology Co., Ltd., brand 104333, average particle size 50 nm.

[0056] Preparation of hydroxyl-terminated acrylate

[0057] (1) Preparation of hydrophilic oligomer diol: a four-necked flask equipped with a magnetic stirrer, a thermometer, a N2 inlet tube and an air-cooled condenser was installed in a jacketed electric resistance heater, 300.2 g (2 mol) of tartaric acid, 160 g (2.6 mol) of ethylene glycol and 1.2 g of concentrated sulfuric acid were added, and the system was stirred for 2 h under nitrogen protection. The dehydration polycondensation reaction was carried out by controlling the temperature of the flask at 60°C. The top temperature of the condenser was controlled below 100°C during the temperature rising process. The reaction system was vacuumed for about 5 min every 0.5 h during the process to remove small molecular by-products, and the reaction was allowed to reach equilibrium until there was no obvious change in the weight of the reaction system. Then 44.6 g (0.72 mol) of ethylene glycol was added and the reaction was continued for 1 h. Then the temperature was gradually increased to 120°C and the vacuum degree was ≥0.095 MPa. The hydroxyl value was 236 mg KOH / g. A hydrophilic oligomer diol with a number average molecular weight of 400 g / mol was prepared, which was recorded as A.

[0058] (2) Preparation of the terminal hydroxyl acrylate: A three-necked flask equipped with a magnetic stirrer, a thermometer and an air-cooled condenser was installed in a mantle electric heater, 400 g (1 mol) of the hydrophilic oligomer diol A and a small amount of 7.21 g (0.1 mol) of acrylic acid and 1.18 g (0.0047 mol) of iodine were added, and the mixture was reacted at boiling for 6 h; after the reaction mixture was cooled by adding 100 g of 3% NaCl aqueous solution, the reaction product was extracted into dichloromethane; the organic solution was washed with 200 g of 5% Na2S2O3 aqueous solution, the upper aqueous solution was removed, and then 5 g of MgSO4 was added to dry the organic solution, the solvent was distilled off, and the product was distilled under vacuum to obtain the synthesized terminal hydroxyl acrylate, denoted as B.

[0059] Preparation of the modified acrylate resin of Preparation Example 2

[0060] Under a nitrogen atmosphere, 201.8 g (1.20 mol) of hexamethylene diisocyanate, 500 g (1 mol) of the polyester diol PCL-2053 (number average molecular weight 500 g / mol), 0.24 g of hydroquinone and 1.8 g of dibutyltin dichloride catalyst were added to a four-necked flask, and after stirring at room temperature, the temperature was increased to 90°C and stirred for 3.5 h, and then under the protection of a nitrogen atmosphere, the temperature was increased to 100°C, and 90 g of the terminal hydroxyl acrylate B was gradually added in one portion, and after stirring for 1 h, the NCO group content in the system was monitored, and the NCO mass percentage content was measured to be > 0.05%, and then 30 g of the terminal hydroxyl acrylate B was added dropwise, and after stirring for 1 h, the NCO group content in the system was monitored, and the above steps were repeated until the NCO content was ≤ 0.05%, after which the addition of the terminal hydroxyl acrylate B was stopped and the heating was stopped, i.e. the isocyanate groups exposed at the end of the molecular chain were substantially completely reacted, the temperature was decreased to 40°C, and the product was discharged, to obtain the modified acrylate resin, denoted as A-1, which had a viscosity of 11000 cps at 25°C.

[0061] Preparation of the modified acrylate resin of Preparation Example 3

[0062] In a four-necked flask, 301.7 g (1.15 mol) of dicyclohexylmethane-4,4-diisocyanate, 900 g (1 mol) of polyester diol POL-1125 (number average molecular weight of 900 g / mol), 0.35 g of o-methyl hydroquinone, and 3 g of trimethyltin chloride catalyst were added under a nitrogen atmosphere. After stirring uniformly at room temperature, the temperature was raised to 115°C, and stirring was performed for 5 h. Then, the temperature was lowered to 105°C under nitrogen atmosphere protection, and 90 g of hydroxyl acrylate B was gradually added in one portion by dripping. After stirring for 1 h, the content of NCO groups in the system was monitored. The measured NCO mass percentage content was greater than >0.05%. Then, 30 g of hydroxyl acrylate B was added by dripping. After stirring for 1 h, the content of NCO groups in the system was monitored. The above steps were repeated until the NCO content was ≤0.05%. Then, the addition of hydroxyl acrylate B was stopped, and heating was stopped. That is, the isocyanate groups exposed at the ends of the molecular chains were substantially completely reacted. The temperature was lowered to 40°C, and the product was discharged. A modified acrylate resin was obtained, which was recorded as A-2. The viscosity of A-2 at 25°C was 22000 cps.

[0063] Preparation of modified acrylate resin of Preparation Example 4

[0064] In a four-necked flask, 277.9 g (1.25 mol) of isophorone diisocyanate, 600 g (1 mol) of polyester diol POL-1180 (number average molecular weight of 600 g / mol), 0.3 g of hydroquinone, and 2.5 g of dibutyltin dichloride catalyst were added under a nitrogen atmosphere. After stirring uniformly at room temperature, the temperature was raised to 110°C, and stirring was performed for 4.2 h. Then, the temperature was lowered to 100°C under nitrogen atmosphere protection, and 90 g of hydroxyl acrylate B was gradually added in one portion by dripping. After stirring for 1 h, the content of NCO groups in the system was monitored. The measured NCO mass percentage content was greater than >0.05%. Then, 30 g of hydroxyl acrylate B was added by dripping. After stirring for 1 h, the content of NCO groups in the system was monitored. The above steps were repeated until the NCO content was ≤0.05%. Then, the addition of hydroxyl acrylate B was stopped, and heating was stopped. That is, the isocyanate groups exposed at the ends of the molecular chains were substantially completely reacted. The temperature was lowered to 40°C, and the product was discharged. A modified acrylate resin was obtained, which was recorded as A-3. The viscosity of A-3 at 25°C was 17000 cps.

[0065] Preparation of hydrophilic structure-containing photocurable coating of Example 1

[0066] Into a double planetary mixing power reaction kettle, 40 parts of modified acrylate resin A-1, 15 parts of hydroxyethyl acrylate, 10.5 parts of pentaerythritol triacrylate were sequentially added and stirred and mixed for 2 h, then 15 parts of propylene glycol monoalkyl ether, 5 parts of cyclopentanone, 10 parts of nano silica sol (NALCO 1115), 3 parts of Irgacure 369, 1 part of TPO, 0.2 parts of BYK 361, 0.3 parts of BKY 054 were added into the reaction kettle and stirred and mixed for 1.5 h, then vacuum degassing was performed, and the product was discharged, thereby obtaining a hydrophilic structure-containing photocuring coating, denoted as A1.

[0067] Preparation of a hydrophilic structure-containing photocuring coating according to Example 2

[0068] Into a double planetary mixing power reaction kettle, 25 parts of modified acrylate resin A-2, 10 parts of isobornyl acrylate, 20 parts of diethylene glycol diacrylate were sequentially added and stirred and mixed for 2 h, then 20 parts of propylene glycol alkyl ether acetate, 10 parts of n-butyl ketone, 5 parts of spherical mesoporous silica (104437), 1.7 parts of Irgacure 184, 3 parts of TPO, 0.2 parts of EFKA 3600, 0.1 parts of BKY 354 were added into the reaction kettle and stirred and mixed for 1.5 h, then vacuum degassing was performed, and the product was discharged, thereby obtaining a hydrophilic structure-containing photocuring coating, denoted as A2.

[0069] Preparation of a hydrophilic structure-containing photocuring coating according to Example 3

[0070] Into a double planetary mixing power reaction kettle, 31.7 parts of modified acrylate resin A-3, 20 parts of isobornyl acrylate, 5 parts of pentaerythritol tetraacrylate were sequentially added and stirred and mixed for 2 h, then 30 parts of cyclopentanone, 8 parts of butyl acetate, 2 parts of spherical mesoporous silica (104333), 2.5 parts of Irgacure 2959, 1.2 parts of TPO-L, 0.1 parts of BYK 333, 0.2 parts of BKY 1790 were added into the reaction kettle and stirred and mixed for 1.5 h, then vacuum degassing was performed, and the product was discharged, thereby obtaining a hydrophilic structure-containing photocuring coating, denoted as A3.

[0071] Preparation of a reference photocuring coating according to Comparative Example 1

[0072] The photocuring coating was prepared according to the method of Example 1, except that the modified acrylate resin A-1 was replaced by the same weight fraction of acrylate resin 7224 (purchased from Guangdong Hengzhiguang New Material Co., Ltd., viscosity at 25°C of 9000 cps), and the other conditions were the same as those of Example 1, thereby obtaining a reference photocuring coating, denoted as DA1.

[0073] Preparation of a reference photocuring coating according to Comparative Example 2

[0074] The photocuring coating was prepared according to the method of Example 2, except that 5 parts of the spherical mesoporous silica (104437) was replaced by the same weight part of n-butanone, and the rest of the conditions were the same as those of Example 2, to prepare a reference photocuring coating, which was recorded as DA2.

[0075] Preparation of the reference photocuring coating of Comparative Example 3

[0076] The photocuring coating was prepared according to the method of Example 3, except that the modified acrylate resin A-3 was replaced by the same weight part of a difunctional polyurethane acrylate resin Trust 7130 (purchased from Shenzhen Youyang Technology Co., Ltd., with a viscosity of 15000 cps at 25°C), and 2 parts of the spherical mesoporous silica (104333) was replaced by the same weight part of butyl acetate, and the rest of the conditions were the same as those of Example 3, to prepare a reference photocuring coating, which was recorded as DA3.

[0077] Test Example

[0078] The photocuring coating prepared in the above examples and comparative examples was used to prepare a coating according to the following method: the photocuring coating prepared above was sprayed on the surface of a glass substrate, pre-baked at 80°C for 15 min, and then photocured with a mercury lamp with a wavelength of 405 nm, with the radiation intensity controlled at 5000 mj / cm 2 , to obtain a transparent coating with a thickness of 10 μm. The transparent coating prepared was tested for hydrophilicity, hydrophilicity, hardness, haze, and adhesion according to the following methods, and the results are shown in Table 1.

[0079] (1) Hydrophilicity test (water contact angle test)

[0080] The water contact angle of the coating was tested with a water contact angle tester.

[0081] (2) Transmittance test

[0082] The transmittance of the coating was tested with a desktop spectrophotometer YS6002-M.

[0083] (3) Hardness test

[0084] The test was performed according to the method of standard GB / 6739T: a Japanese Mitsubishi pencil with different hardness was pushed over the coating on the surface of the substrate under a force of 1 kg, and the coating surface was not damaged after 3 times, which was recorded as OK; if there was a slight scratch in 1 of the 3 times, the hardness of the pencil at that time was recorded as the hardness of the coating;

[0085] B = BLACK, H = HARD. The greater the B value, the blacker and softer the pencil; the greater the H value, the harder and lighter the pencil. The pencils are divided into 10B, 9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, 10H, 10B being the softest and darkest ink, H being harder and lighter ink, and 10H being the hardest and lightest ink.

[0086] (4) Haze Test

[0087] The water vapor generated by boiling water is sprayed onto the surface of the coating, and after the surface of the coating cools to room temperature, the haze value before and after the coating is tested using a haze meter (haze = amount of scattered transmitted light / amount of transmitted light).

[0088] (5) Adhesion Test

[0089] The adhesion is tested by the crosshatch method: 6x6 1mm x 1mm small squares are drawn on the surface of the sample to be tested using a sharp knife, and then a piece of tape is attached to the center of the grid formed, and then pulled off smoothly, and the phenomenon of paint peeling is observed and judged according to the following standards:

[0090] 5B - the edges of the cuts are completely smooth, and there is no peeling at the edges and intersections of the grid;

[0091] 4B - there is a small piece of peeling at the intersection of the cuts, and the actual damage in the grid area is not more than 5%;

[0092] 3B - there is a small piece of peeling at the edges and intersections of the cuts, and the actual damage in the grid area is 5% (not including the endpoint value) to 15%;

[0093] 2B - there is a piece of peeling at the edges and intersections of the cuts, and the actual damage in the grid area is 15% (not including the endpoint value) to 35%;

[0094] 1B - there is a large piece of peeling at the edges and intersections of the cuts, and the actual damage in the grid area is 35% (not including the endpoint value) to 65%;

[0095] 0 - some of the squares are partially or completely peeled off, and the actual damage in the grid area is greater than 65%.

[0096] Table 1

[0097]

[0098]

[0099] As can be seen from the results in Table 1, compared with the comparative examples, the photocurable coating provided by the present application has a lower water contact angle and can maintain a lower haze in a water vapor environment, achieving the purpose of anti-fogging. In addition, the photocurable coating provided by the present application also has good adhesion and hardness, and can meet the application requirements, and has practicality.

[0100] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary only, and the scope of the present application is not limited by the above-described embodiments, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments without departing from the principles and spirit of the present application within the scope of the present application.

Claims

1. A photocurable coating containing a hydrophilic structure, characterized in that, The hydrophilic structure photocurable coating contains a modified acrylate resin in a mass ratio of 1:(0.125~0.8):(0.125~0.8):(0.025~0.4):(0.025~0.2):(0~1.6):(0~0.04), a monofunctional diluent, a polyfunctional diluent, nanoparticles, a photoinitiator, and optional solvents and additives; the modified acrylate resin is a double-bonded acrylate resin obtained by reacting diisocyanate and diol I with terminal hydroxyl acrylate; the modified acrylate resin has the structure shown in formula (1); the terminal hydroxyl acrylate is obtained by purifying a hydrophilic oligomer diol having the structure shown in formula (2) and acrylic acid by dehydration condensation reaction in the presence of iodine; the nanoparticles are nano silica sol and / or mesoporous silica; Equation (1), In formula (1), R1 is a group derived from diol I, R2 is a group derived from diisocyanate, R3 is a group derived from the hydrophilic oligomer diol shown in formula (2), and n is an integer from 1 to 7. Equation (2), In formula (2), R4 is a C1~C6 alkylene group and the side chain includes at least one hydroxyl group, R5 is a C1~C6 alkylene group, and m is an integer from 1 to 7.

2. The hydrophilic structural photocurable coating according to claim 1, characterized in that, Based on the total weight of the hydrophilic structure photocurable coating, the modified acrylic resin content is 25-40 parts by weight, the monofunctional diluent content is 5-20 parts by weight, the multifunctional diluent content is 5-20 parts by weight, the nanoparticle content is 1-10 parts by weight, the photoinitiator content is 1-5 parts by weight, the solvent content is 20-40 parts by weight, and the additive content is 0-1 parts by weight.

3. The hydrophilic structure-containing photocurable coating according to claim 1, characterized in that, The modified acrylate resin has a viscosity of 5000~35000 cps at 25°C.

4. The hydrophilic structure-containing photocurable coating according to claim 1, characterized in that, The functionality of the multifunctional diluent is 2 to 6.

5. The hydrophilic structural photocurable coating according to claim 1, characterized in that, The average particle size of the nano-silica sol is 1~100nm.

6. The hydrophilic structure-containing photocurable coating according to claim 1, characterized in that, The average particle size of the mesoporous silica is 50~150 nm.

7. The hydrophilic structural photocurable coating according to claim 1, characterized in that, The modified acrylate resin is prepared by a method comprising the following steps: S1. Diisocyanate and diol I are subjected to an addition reaction in the presence of a polymerization inhibitor and an initiator to obtain a polyurethane prepolymer with isocyanate double-terminated ends; S2. The isocyanate-terminated polyurethane prepolymer obtained in step S1 is subjected to a capping reaction with a hydroxyl-terminated acrylate to obtain a modified acrylate resin with double bonds.

8. The hydrophilic structure-containing photocurable coating according to claim 1, characterized in that, The molar ratio of acrylic acid, hydrophilic oligomer diol and iodine is 1:(8~12):(0.01~0.05).

9. The hydrophilic structural photocurable coating according to claim 1, characterized in that, The hydrophilic oligomer diol has a hydroxyl value of 120~280 mg KOH / g.

10. The hydrophilic structure-containing photocurable coating according to claim 1, characterized in that, The number average molecular weight of the hydrophilic oligomer diol is 300~1500 g / mol.

11. The photocurable coating containing a hydrophilic structure according to claim 1, characterized in that, The hydrophilic oligomer diol is obtained by polycondensation of a diacid having the structure shown in formula (3) and a diol II having the structure shown in formula (4) in the presence of a catalyst. Equation (3), Equation (4) In formula (3), R4 is a C1~C6 alkylene group and the side chain includes at least one hydroxyl group; In formula (4), R5 is a C1~C6 alkylene group.

12. The photocurable coating containing a hydrophilic structure according to claim 11, characterized in that, The molar ratio of the dicarboxylic acid to diol II is 1:(1.5~1.8).

13. The photocurable coating containing a hydrophilic structure according to claim 11, characterized in that, The amount of catalyst added is 0.2 to 1 wt% of the total mass of the reaction raw materials.

14. The method for preparing a hydrophilic structural photocurable coating according to any one of claims 1 to 13, characterized in that, The preparation method involves mixing and stirring a modified acrylate resin, a monofunctional diluent, a polyfunctional diluent, a photoinitiator, and optional solvents and additives until homogeneous, and then discharging the mixture in the dark to obtain a photocurable coating containing a hydrophilic structure.

15. An anti-fog coating, characterized in that, The anti-fog coating is prepared using the hydrophilic structured photocurable coating described in any one of claims 1 to 13.

16. A method for preparing an anti-fog coating, characterized in that, The preparation method includes applying the hydrophilic structured photocurable coating as described in any one of claims 1 to 13 onto a substrate, and obtaining an anti-fog coating after curing.

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