A waterproof UV coating and a preparation method thereof

Abstract

The waterproof UV paint provided by the application contains polyurethane acrylate, monofunctional long-chain aliphatic diluent, multifunctional diluent, modified polysulfane, photoinitiator, anti-hydrolysis agent and optional auxiliary agent; the mass ratio of the polyurethane acrylate and the modified polysulfane is 1:(0.08-0.3); the mass ratio of the monofunctional long-chain aliphatic diluent and the multifunctional diluent is 1:(0.2-1.8); the polyurethane acrylate is difunctional aliphatic polyurethane acrylate; the modified polysulfane has the structure described in formula (1). The key of the application is to introduce the modified polysulfane with specific structure and content, and at the same time, to use the monofunctional long-chain aliphatic diluent and the multifunctional diluent and strictly control the ratio between the two, on the basis of which, the UV paint with high surface curing degree and excellent waterproof property is obtained in cooperation with the polyurethane acrylate, the photoinitiator, the anti-hydrolysis agent and the auxiliary agent.

Description

Technical Field

[0001] This invention belongs to the field of UV coatings, specifically relating to a waterproof UV coating and its preparation method. Background Technology

[0002] UV curing technology, hailed as a "green industrial technology for the 21st century," uses ultraviolet lamps for curing. The curing reaction is extremely rapid, completing within seconds. Compared to traditional water-based coatings, UV coatings cured using this technology offer the advantage of rapid curing, effectively shortening the construction cycle and being unrestricted by season or region, making them widely applicable across various fields. However, free-radical UV coatings are susceptible to oxygen inhibition during the curing process, leading to poor surface curing and thus affecting and limiting their practical applications. Furthermore, the presence of numerous ester bonds in the cured molecules of UV coatings results in poor hydrolysis resistance in most commercially available UV coatings, limiting their application range and scenarios. Therefore, the search is for a UV coating with high surface curing efficiency and excellent waterproof properties. Summary of the Invention

[0003] The primary objective of this invention is to address the problems of poor surface curing and inadequate hydrolysis resistance in currently available UV coatings by proposing a UV coating with high surface curing degree and excellent waterproof performance.

[0004] Specifically, the waterproof UV coating contains polyurethane acrylate, a monofunctional long-chain aliphatic diluent, a polyfunctional diluent, modified polythiol, a photoinitiator, an anti-hydrolysis agent, and optional additives; the mass ratio of the polyurethane acrylate to the modified polythiol is 1:(0.08-0.3); the mass ratio of the monofunctional long-chain aliphatic diluent to the polyfunctional diluent is 1:(0.2-1.8); the polyurethane acrylate is a difunctional aliphatic polyurethane acrylate; the modified polythiol has the structure described in formula (1); the monofunctional long-chain aliphatic diluent is selected from at least one of laurate acrylate, isodecanyl acrylate, stearate acrylate, and isotriadecyl acrylate;

[0005]

[0006] In equation (1), R1 is C1~C 12 Alkylene, C1-C 12 Cycloalkylene, C6-C 30 aryl, C6-C 30 arylene alkyl or C6-C 30 alkylene aryl, R2 is C1 to C2. 10 Alkylene, R3 is a group derived from trifunctional and / or tetrafunctional polythiol compounds, and n is an integer from 1 to 10.

[0007] In a preferred embodiment, the mass ratio of the polyurethane acrylate, monofunctional long-chain aliphatic diluent, polyfunctional diluent, modified polythiol, photoinitiator, anti-hydrolysis agent and additives is 1:(0.4-1.5):(0.2-1.2):(0.08-0.3):(0.02-0.2):(0.002-0.07):(0-0.07).

[0008] In a preferred embodiment, the polyurethane acrylate content is 30-50 parts by weight, the monofunctional long-chain aliphatic diluent content is 20-45 parts by weight, the polyfunctional diluent content is 10-35 parts by weight, the modified polythiol content is 4-8 parts by weight, the photoinitiator content is 1-5 parts by weight, the anti-hydrolysis agent content is 0.1-2 parts by weight, and the additive content is 0-2 parts by weight.

[0009] In a preferred embodiment, the modified polythiol is prepared by the following method:

[0010] S1. A polyisocyanate and a diamine are subjected to a capping reaction to obtain a polyurea prepolymer with isocyanate double capping.

[0011] S2. The polyurea prepolymer obtained in step S1 and the polythiol compound are subjected to an addition reaction in the presence of an initiator to obtain the modified polythiol.

[0012] In a preferred embodiment, the molar ratio of the diamine, polyisocyanate, and polythiol compound is 1:(1.2-1.6):(0.2-1.6).

[0013] In a preferred embodiment, the amount of the initiator is 0.1 to 0.3 wt% of the total mass of the reactants.

[0014] In a preferred embodiment, the modified polythiol has a thiol content of 5-20 wt%.

[0015] In a preferred embodiment, the polyisocyanate is selected from at least one of toluene diisocyanate, norbornene diisocyanate, isophorone diisocyanate, isophenyl dimethyl diisocyanate, 4,4-dicyclohexylmethane diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate.

[0016] In a preferred embodiment, the diamine is selected from at least one of ethylenediamine, 1,2-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, and 1,10-decanediamine.

[0017] In a preferred embodiment, the polythiol compound is a trifunctional and / or tetrafunctional polythiol compound.

[0018] In a preferred embodiment, the polythiol compound is selected from at least one of trimethylolpropane tris(3-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetras(3-mercaptoacetate), pentaerythritol tetras(3-mercaptopropionate), and pentaerythritol tetras(3-mercaptobutyrate).

[0019] In a preferred embodiment, the viscosity of the polyurethane acrylate at 25°C is 1000–15000 cps.

[0020] In a preferred embodiment, the functionality of the multifunctional active diluent is 2 to 4.

[0021] In a preferred embodiment, the multifunctional active diluent is selected from dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), neopentyl glycol diacrylate (NPGDA), propoxylated neopentyl glycol diacrylate (PO-NPGDA), 1,6-hexanediol diacrylate (HDDA), 1,4-butanediol diacrylate (BDDA), diethylene glycol diacrylate (DEGDA), triethylene glycol diacrylate (TEGDA), methyl etherified propoxy pentaerythritol diacrylate, tricyclic... At least one of the following: decanediethanol diacrylate (DCPDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), pentaerythritol triacrylate (PETA), pentaerythritol trimethacrylate (PETMA), propoxylated glycerol triacrylate (PO-GTA), tri(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), and dipentaerythritol hexaacrylate (DPI-IA).

[0022] The second objective of this invention is to provide a method for preparing the above-mentioned waterproof UV coating. The method includes mixing and stirring polyurethane acrylate, monofunctional long-chain aliphatic diluent, polyfunctional diluent, modified polythiol, photoinitiator, anti-hydrolysis agent and additives evenly, and then discharging the material in the dark to obtain the waterproof UV coating.

[0023] The key to this invention lies in introducing modified polythiols with specific structures and adjusting the ratio between polyurethane acrylate and modified polythiols. Simultaneously, monofunctional long-chain aliphatic diluents and multifunctional diluents are used and their ratio is strictly controlled. Based on this, a waterproof UV coating is obtained by synergistically combining it with photoinitiators, anti-hydrolysis agents and additives. It has the characteristics of high surface curing degree and excellent waterproof performance. The reasons for this are speculated to be as follows: Firstly, modified polythiols contain thiourea structures, forming a dense macromolecular chain structure containing polyurea on the coating surface. Furthermore, the thiol functionality of modified polythiols is 2-3, thereby increasing the crosslinking degree of the coating surface, effectively preventing surface moisture from entering the coating interior, and improving the coating's waterproof performance. Simultaneously, modified polythiols can effectively reduce oxygen inhibition during UV curing, solving the problem of poor surface curing and improving the surface curing degree of UV coatings. Secondly, the combination of monofunctional long-chain aliphatic diluents and multifunctional diluents not only increases the reaction rate and crosslinking density of UV coatings, enhancing their surface curing degree, but also, when combined with anti-hydrolysis agents, further improves the waterproof performance of UV coatings. In summary, the waterproof UV coating provided by this invention, through the synergistic combination of polyurethane acrylate, monofunctional long-chain aliphatic diluent, multifunctional diluent, modified polythiol, photoinitiator, anti-hydrolysis agent, and additives, not only has a high degree of surface curing but also excellent waterproof performance. Even after being placed in a 95% RH environment for 1500 hours, it can still maintain its appearance without deformation (deformation includes surface wrinkling and unevenness, as well as blistering on the coating surface). Detailed Implementation

[0024] The waterproof UV coating provided by this invention contains polyurethane acrylate, a monofunctional long-chain aliphatic diluent, a multifunctional diluent, modified polythiol, a photoinitiator, an anti-hydrolysis agent, and optional additives. The mass ratio of the polyurethane acrylate to the modified polythiol is 1:(0.08-0.3), such as 1:0.08, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, or any value between them. The mass ratio of the diluent is 1:(0.2 to 1.8), such as 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8 or any value between them; the polyurethane acrylate is a bifunctional aliphatic polyurethane acrylate; the modified polythiol has the structure of formula (1); the monofunctional long-chain aliphatic diluent is selected from at least one of laurate acrylate, isodecanyl acrylate, stearate acrylate and isotrimethylene acrylate;

[0025]

[0026] In equation (1), R1 is C1~C12 Alkylene, C1-C 12 Cycloalkylene, C6-C 30 aryl, C6-C 30 arylene alkyl or C6-C 30 alkylene aryl, R2 is C1 to C2. 10 Alkylene, R3 is a group derived from trifunctional and / or tetrafunctional polythiol compounds, and n is an integer from 1 to 10. Wherein, the C1 to C... 12 Specific examples of alkylene groups include, but are not limited to, at least one selected from: methylene, ethylene, n-propylene, isopropylene, n-butylene, secondary butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene, neopentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, and n-dodecylene. The C1-C1 group... 12 Specific examples of cyclohexenes include, but are not limited to, at least one of cyclopentylene, cyclohexylene, and dicyclohexylene. The C6-C6... 30 Specific examples of arylene groups include, but are not limited to, at least one of: phenylene, biphenylene, bitolylene, and naphthylene. The C6-C6... 30 The arylene alkyl group can be tolyl. The C6-C6 group... 30 The alkylene aryl group can be diphenylenemethyl and / or phenylenemethyl. The C1-C1 group... 10 Specific examples of alkylene groups include, but are not limited to, at least one of: methylene, ethylene, n-propylene, isopropylene, n-butylene, secondary butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, tert-pentylene, neopentylene, n-hexylene, n-heptylene, and n-octylene. n is an integer from 1 to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0027] In this invention, the preferred mass ratio of the polyurethane acrylate to the monofunctional long-chain aliphatic diluent is 1:(0.4–1.5), such as 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, or any value between them. The preferred mass ratio of the polyurethane acrylate to the polyfunctional diluent is 1:(0.2–1.2), such as 1:0.2, 1:0.5, 1:0.8, 1:1, 1:1.2, or any value between them. The preferred mass ratio of the polyurethane acrylate to the modified polythiol is 1:(0.08–0.3), such as 1:0.08, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, or any value between them. The preferred mass ratio of the polyurethane acrylate to the photoinitiator is 1:(0.02–0.2), such as 1:0.02, 1:0.05, 1:0.08, 1:0.1, 1:0.12, 1:0.15, 1:0.18, or 1:0.2. The preferred mass ratio of the polyurethane acrylate to the anti-hydrolysis agent is 1:(0.002–0.07), such as 1:0.002, 1:0.005, 1:0.008, 1:0.01, 1:0.02, 1:0.05, or 1:0.07, or any value between them. The preferred mass ratio of the polyurethane acrylate to the additives is 1:(0–0.07), such as 1:0, 1:0.01, 1:0.02, 1:0.05, or 1:0.07, or any value between them.

[0028] In this invention, the content of the polyurethane acrylate is preferably 30-50 parts by weight, such as 30, 32, 35, 38, 40, 42, 45, 48, 50 parts by weight or any value between them. The content of the monofunctional long-chain aliphatic diluent is preferably 20-45 parts by weight, such as 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45 parts by weight or any value between them. The content of the polyfunctional diluent is preferably 10-35 parts by weight, such as 10, 15, 20, 25, 30, 35 parts by weight or any value between them. The content of the modified polythiol is preferably 4-8 parts by weight, such as 4, 5, 6, 7, 8 parts by weight or any value between them. The content of the photoinitiator is preferably 1-5 parts by weight, such as 1, 2, 3, 4, 5 parts by weight or any value between them. The content of the anti-hydrolysis agent is preferably 0.1 to 2 parts by weight, such as 0.1, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2 parts by weight or any value between them. The content of the auxiliary agent is preferably 0 to 2 parts by weight, such as 0, 0.2, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2 parts by weight or any value between them.

[0029] In this invention, the modified polythiol can be prepared by the following method:

[0030] S1. A polyisocyanate and a diamine are subjected to a capping reaction to obtain a polyurea prepolymer with isocyanate double capping.

[0031] S2. The polyurea prepolymer obtained in step S1 and the polythiol compound are subjected to an addition reaction in the presence of an initiator to obtain the modified polythiol.

[0032] In the preparation process of the modified polythiol described above, in step S1, the temperature of the end-capping reaction is preferably 5 to 30°C, such as 5°C, 10°C, 15°C, 20°C, 25°C, 30°C or any value between them; the time of the end-capping reaction is preferably 2 to 5 hours, such as 2 hours, 2.2 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours or any value between them.

[0033] In the preparation process of the modified polythiol described above, in step S2, the temperature of the addition reaction is preferably 20 to 40°C, such as 20°C, 25°C, 30°C, 35°C, 40°C or any value between them; the time of the addition reaction is preferably 2 to 10 hours, such as 2 hours, 5 hours, 8 hours, 10 hours or any value between them.

[0034] In this invention, the molar ratio of the diamine, polyisocyanate, and polythiol compound is preferably 1:(1.2-1.6):(0.2-1.6). Specifically, with 1 mol of diamine as the unit of measurement, the molar content of the polyisocyanate is preferably 1.2-1.6 mol, such as 1.2 mol, 1.3 mol, 1.4 mol, 1.5 mol, 1.6 mol, or any value between these values; the molar content of the polythiol compound is preferably 0.2-1.6 mol, such as 0.2 mol, 0.4 mol, 0.6 mol, 0.8 mol, 1 mol, 1.2 mol, 1.4 mol, 1.6 mol, or any value between these values.

[0035] In this invention, the amount of the initiator is preferably 0.1 to 0.3 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%, or any value between them. The initiator is preferably selected from at least one of stannous isoate, trimethyltin chloride, dibutyltin dilaurate, dibutyltin dichloride, and methyltin trichloride.

[0036] In this invention, since isocyanates are sensitive to moisture, in order to ensure the smooth reaction of polyisocyanates with diamines and polythiols, the reaction vessel and reactants need to be dehydrated before the reaction is carried out, and the reaction is conducted under an inert atmosphere. In one specific embodiment, the modified polythiols can be prepared as follows: under an inert gas atmosphere, dehydrated polyisocyanates and diamines are added to a three-necked flask, the reaction temperature is controlled at 5–30°C, and the reaction is stirred for 2–5 hours to allow the polyisocyanates and diamines to undergo end-capping reaction, obtaining a polyurea prepolymer with isocyanate double-terminated ends; then, polythiols and initiators are added for an addition reaction, the system temperature is controlled at 20–40°C, the reaction is stirred for 2–10 hours, and the reaction is terminated when the thiol content is 5–20 wt%, thus obtaining the modified polythiols.

[0037] In this invention, the viscosity of the polyurethane acrylate at 25°C is preferably 1000–15000 cps, such as 1000 cps, 2000 cps, 5000 cps, 8000 cps, 10000 cps, 12000 cps, 15000 cps, or any value between them. Specific examples of the polyurethane acrylate include, but are not limited to, at least one of: EBECRYL 270, EBECRYL 271, EBECRYL 284, EBECRYL 8307, EBECRYL 8254, EBECRYL 8411, 7210B, 7220F, 7223F, 7224, 7233F, 7295, Trust 7116, Trust 7118, Trust 7128, and Trust 7166.

[0038] In this invention, the anti-hydrolysis agent can react with the terminal carboxyl groups, terminal amine groups, and terminal hydroxyl groups generated during the hydrolysis of the UV coating to generate stable and harmless products, effectively preventing further degradation and chain scission of the UV coating, thereby improving the waterproofness of the UV coating. The anti-hydrolysis agent is preferably a carbodiimide-based anti-hydrolysis agent, which can be a small molecule carbodiimide such as dicyclohexylcarbodiimide and / or diisopropylcarbodiimide, or a high molecular weight carbodiimide anti-hydrolysis agent such as Stabaxol P100, Stabaxol P200, S-9000, etc. 3rd grade.

[0039] In this invention, the photoinitiator may be selected from at least one of Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 754, Irgacure 819, Irgacure 907, Irgacure 1173 and TPO.

[0040] In this invention, the additives are preferably leveling agents and / or defoamers. The leveling agent can be any substance known to those skilled in the art capable of improving the leveling properties of coatings, specifically preferably at least one of BYK307, BYK333, BYK358, BYK361, BYK366, EFKA3600, EFKA3883, and EFKA3886. The defoamer can be any substance known to those skilled in the art capable of eliminating or reducing bubble formation in coatings, specifically preferably at least one of BYK020, BKY054, BYK352, BYK354, BYK357, BKY1790, and BKY1794.

[0041] In this invention, the preparation method of the waterproof UV coating includes mixing and stirring polyurethane acrylate, a monofunctional long-chain aliphatic diluent, a multifunctional diluent, modified polythiol, a photoinitiator, an anti-hydrolysis agent, and additives until homogeneous, and then discharging the mixture in the dark to obtain the waterproof UV coating. In a specific embodiment, the method includes: sequentially adding polyurethane acrylate resin, a monofunctional long-chain aliphatic diluent, a multifunctional diluent, modified thiol, and an anti-hydrolysis agent into a double planetary hybrid reactor, stirring for 1-3 hours; then adding the photoinitiator and additives, stirring for 1-2 hours, followed by vacuum degassing, and then discharging and sealing in packaging to obtain the waterproof UV coating. Furthermore, strict avoidance of white light is required throughout the entire preparation and stirring process.

[0042] The present invention will be described in detail below through specific embodiments.

[0043] In the following examples and comparative examples, the parts of raw materials refer to parts by weight.

[0044] Preparation Example 1: Preparation of Modified Polythiol

[0045] Under a nitrogen atmosphere, 100.8 g of hexamethylene diisocyanate (0.6 mol) was added to a three-necked flask, followed by the weighing of 24.4 g of ethylenediamine (0.4 mol). The temperature was controlled at 10 °C, and the ethylenediamine was added to the three-necked flask in 2-3 portions, stirring for 1.5 h. Then, 195.6 g of pentaerythritol tetrakis(3-mercaptopropionic acid) (0.4 mol) and 0.9 g of dibutyltin dilaurate initiator were added, and the mixture was stirred at 30 °C for 5 h. The reaction was terminated when the thiol content was found to be around 17%, and the resulting product was designated as modified polythiol S-1.

[0046] Preparation Example 2: Preparation of Modified Polythiol

[0047] Under a nitrogen atmosphere, 117.9 g of 4,4-dicyclohexylmethane diisocyanate (0.45 mol) was added to a three-necked flask, followed by the weighing of 18.4 g of ethylenediamine (0.3 mol). The temperature was controlled at 18 °C, and the ethylenediamine was added to the three-necked flask in 2-3 portions, with stirring for 3 h. Then, 146.7 g of pentaerythritol tetrakis(3-mercaptopropionic acid) (0.3 mol) and 0.42 g of dibutyltin dichloride initiator were added, and the mixture was stirred at 35 °C for 3 h. The reaction was terminated when the thiol content was found to be around 9%. The resulting product was designated as modified polythiol S-2.

[0048] Preparation Example 3: Preparation of Modified Polythiol

[0049] Under a nitrogen atmosphere, 100.8 g of hexamethylene diisocyanate (0.6 mol) was added to a three-necked flask, followed by the weighing of 24.4 g of ethylenediamine (0.4 mol). The temperature was controlled at 5 °C, and the ethylenediamine was added to the three-necked flask in 2-3 portions, stirring for 3 h. Then, 159.3 g of trimethylolpropane tris(3-mercaptoacetic acid) (0.4 mol) and 0.3 g of dibutyltin dichloride initiator were added, and the mixture was stirred at 25 °C for 4 h. The reaction was terminated when the thiol content was found to be around 15%, and the resulting product was designated as modified polythiol S-3.

[0050] Example 1: Preparation of Waterproof UV Coating

[0051] 35 parts of Trust 7116 (purchased from Shenzhen Youyang Technology Co., Ltd., viscosity 8500cps), 32 parts of isotridecyl acrylate (monofunctional long-chain aliphatic diluent), 20 parts of dipropylene glycol diacrylate, 5 parts of dipentaerythritol hexaacrylate, 4 parts of modified polythiol S-1, and 1 part of Stabaxol P200 were sequentially added to a double planetary hybrid reactor and stirred for 2 hours. Then, 3.5 parts of Irgacure 651, 1 part of Irgacure 184, 0.2 parts of EFKA3600, and 0.2 parts of BKY054 were added to the reactor and stirred for 1.5 hours. After vacuum degassing, the product was discharged, thus obtaining a waterproof UV coating, denoted as A1.

[0052] Example 2: Preparation of Waterproof UV Coating

[0053] 50 parts of EBECRYL 271 (purchased from Zhanxin Resin (China) Co., Ltd., viscosity 3000cps), 22 parts of isodecyl acrylate (monofunctional long-chain aliphatic diluent), 15.5 parts of 1,4-butanediol diacrylate, 8 parts of modified polythiol S-2, and 2 parts of Stabaxol P100 were sequentially added to a double planetary hybrid reactor and stirred for 2 hours. Then, 3 parts of TPO, 1 part of Irgacure 369, 0.3 parts of BYK358, and 0.2 parts of BKY354 were added to the reactor and stirred for 1 hour. After vacuum degassing, the product was discharged, thus obtaining a waterproof UV coating, denoted as A2.

[0054] Example 3: Preparation of Waterproof UV Coating

[0055] 40 parts of acrylate resin 7233F (purchased from Guangdong Hengzhiguang Environmental Protection New Materials Co., Ltd., viscosity 5000cps), 33 parts of lauric acid acrylate (monofunctional long-chain aliphatic diluent), 10 parts of trimethylolpropane triacrylate, 7 parts of pentaerythritol tetraacrylate, 6 parts of modified polythiol S-3, and 0.6 parts of diisopropylcarbodiimide were sequentially added to a double planetary hybrid reactor and stirred for 2 hours. Then, 2 parts of Irgacure 754, 2 parts of Irgacure 907, 0.2 parts of EFKA3600, and 0.2 parts of BKY1794 were added to the reactor and stirred for 1 hour. After vacuum degassing, the product was discharged, thus obtaining a waterproof UV coating, denoted as A3.

[0056] Example 4: Preparation of Waterproof UV Coating

[0057] 35 parts of Trust 7166 (purchased from Shenzhen Youyang Technology Co., Ltd., viscosity 6500cps), 45 parts of isotriadecyl acrylate (monofunctional long-chain aliphatic diluent), 10 parts of dipentaerythritol pentaacrylate, 4 parts of modified polythiol S-1, and 1 part of Stabaxol P200 were sequentially added to a double planetary hybrid reactor and stirred for 2 hours. Then, 3.5 parts of Irgacure 651, 1 part of Irgacure 184, 0.2 parts of EFKA3600, and 0.2 parts of BKY054 were added to the reactor and stirred for 1.5 hours. After vacuum degassing, the product was discharged, thus obtaining a waterproof UV coating, denoted as A4.

[0058] Example 5: Preparation of Waterproof UV Coating

[0059] 40 parts of EBECRYL 8307 (purchased from Zhanxin Resin (China) Co., Ltd., viscosity 3850cps), 20 parts of stearic acid acrylate (monofunctional long-chain aliphatic diluent), 35 parts of dipropylene glycol diacrylate, 6 parts of modified polythiol S-1, and 1 part of dicyclohexylcarbodiimide were sequentially added to a double planetary hybrid reactor and stirred for 2 hours. Then, 2 parts of Irgacure 651, 2 parts of Irgacure 184, 0.2 parts of EFKA3600, and 0.2 parts of BKY054 were added to the reactor and stirred for 1.5 hours. After vacuum degassing, the product was discharged, thus obtaining a waterproof UV coating, denoted as A5.

[0060] Comparative Example 1: Preparation of Reference UV Coating

[0061] The reference UV coating was prepared according to the method of Example 1, except that the anti-hydrolysis agent Stabaxol P200 was not added, and the other conditions were the same as in Example 1. The resulting reference UV coating is denoted as DA1.

[0062] Comparative Example 2: Preparation of Reference UV Coating

[0063] The UV coating was prepared according to the method of Example 2, except that isodecyl acrylate (a monofunctional long-chain aliphatic diluent) was replaced with the same weight of isoborneol acrylate (a common monofunctional diluent), and the other conditions were the same as in Example 2. The resulting reference UV coating was denoted as DA2.

[0064] Preparation of reference UV coating in Comparative Example 3

[0065] The UV coating was prepared according to the method of Example 2, except that the same parts by weight of isodec acrylate (a common monofunctional diluent) was used instead of 1,4-butanediol diacrylate (a multifunctional reactive diluent). The other conditions were the same as in Example 2. The resulting reference UV coating was denoted as DA2.

[0066] Preparation of reference UV coating in Comparative Example 4

[0067] The UV coating was prepared according to the method of Example 3, except that modified polythiol S-3 was not added, and the other conditions were the same as in Example 3. The resulting reference UV coating was denoted as DA4.

[0068] Preparation of reference UV coating in Comparative Example 5

[0069] The UV coating was prepared according to the method of Example 4, except that the modified polythiol S-1 was replaced with the same amount of trimethylolpropane tris(3-mercaptoacetate) by weight, and the other conditions were the same as in Example 4. The resulting reference UV coating was denoted as DA5.

[0070] Test case

[0071] The UV coatings obtained in the above examples and comparative examples were photocured using a 395nm wavelength lamp, with a radiation intensity of 3000mJ / cm². 2 After curing, the performance was tested according to the following method, and the results are shown in Table 1.

[0072] (1) Adhesion test: Apply UV coating to a stainless steel substrate with a thickness of 30±5μm. After curing under the above conditions, test the adhesion using the cross-cut adhesion test: Use a sharp knife to cut 6×6 1mm×1mm squares on the surface of the sample to be tested, stick tape to the center of the formed squares, and then peel it off smoothly. Observe the phenomenon of coating peeling off and judge it according to the following standards.

[0073] 5B - The cut edges are completely smooth, with no peeling at the grid edges and intersections;

[0074] 4B - Small pieces peel off at the intersection of the cuts, and the actual damage within the gridded area does not exceed 5%;

[0075] 3B - Small pieces of material peel off at the edges and intersections of the cuts; the actual damage within the gridded area is 5% (excluding endpoint values) to 15%.

[0076] 2B - There is extensive peeling at the edges and intersections of the cuts, and the actual damage within the gridded area is 15% (excluding endpoint values) to 35%;

[0077] 1B - Large areas of peeling are observed at the edges and intersections of the cuts, with actual damage within the gridded area ranging from 35% (excluding endpoint values) to 65%.

[0078] 0 - Some squares have partially or completely peeled off, and the actual damage within the grid area is greater than 65%.

[0079] (2) Hardness test: According to GB / T531-1999 "Rubber pocket hardness test for indentation hardness", the hardness of the UV coating after curing was tested using a Shore hardness tester.

[0080] (3) Scratch resistance test: According to GB / T9279-1988 "Scratch test for paints and varnishes", the scratch resistance of UV coatings after curing was tested using the American Taber710 scratch resistance tester. The instrument was set to apply a constant 5N force vertically to the surface of the test sample to perform the scratch test, and the number of scratches that caused surface damage was recorded.

[0081] (4) Water contact angle test: The UV coating is applied to a stainless steel substrate with a thickness of 30±5μm. After curing under the above conditions, the water contact angle of the UV coating is tested using a water contact angle tester.

[0082] (5) Water vapor transmission rate: According to GB / T1037-88 "Test method for water vapor permeability of plastic films and sheets - cup method", the UV coating cured under the above conditions was made into a disc corresponding to the cup ring. The water vapor transmission rate (g / m³) was tested over 24 hours at a temperature of 23±0.6℃ and a relative humidity of 90±2%. 2 •24h).

[0083] (6) Waterproof performance test: The UV coating was applied to a stainless steel substrate with a thickness of 30±5μm. After curing under the above conditions, it was placed in the ESPEC constant temperature and humidity chamber. The temperature and humidity were set at 25℃@95%RH. After 500h, 750h, 1000h, 1250h and 1500h respectively, the sample was taken out and the coating surface was observed to see if it was deformed (deformation includes surface wrinkling and unevenness and blistering on the coating surface. As long as the coating surface morphology shows the above situation, regardless of the severity of the situation, it indicates that the coating surface has been deformed). At the same time, its adhesion was tested.

[0084] Table 1

[0085]

[0086] As can be seen from the test results in Table 1, the waterproof UV coating provided in this embodiment of the invention not only has a high degree of surface curing, high hardness and scratch resistance, but also excellent waterproof performance. After being placed in a high humidity environment for 1500 hours, the surface does not deform and still has good adhesion.

[0087] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A water repellent UV coating, characterized in that, The waterproof UV coating contains polyurethane acrylate, monofunctional long-chain aliphatic diluent, multifunctional diluent, modified polysulfide, photoinitiator, carbodiimide anti-hydrolysis agent and optional auxiliary agent; the mass ratio of the polyurethane acrylate and the modified polysulfide is 1:(0.08-0.3); the mass ratio of the monofunctional long-chain aliphatic diluent and the multifunctional diluent is 1:(0.2-1.8); the polyurethane acrylate is difunctional aliphatic polyurethane acrylate; the modified polysulfide has the structure shown in formula (1); the monofunctional long-chain aliphatic diluent is selected from at least one of lauryl acrylate, isodecyl acrylate, stearyl acrylate and isotridecyl acrylate; Formula (1), In formula (1), R1is C1-C 12 alkylene, C1-C 12 cycloalkylene, C6-C 30 arylene, C6-C 30 aralkylene, or C6-C 30 alkarylene, R2is C1-C 10 alkylene, R3is a group derived from a tri- and / or tetra-functional polythiol compound, and n is an integer of 1 to 10. The mass ratio of the polyurethane acrylate, monofunctional long-chain aliphatic diluent, multifunctional diluent, modified polysulfide, photoinitiator, carbodiimide anti-hydrolysis agent and auxiliary agent is 1:(0.4-1.5):(0.2-1.2):(0.08-0.3):(0.02-0.2):(0.002-0.07):(0-0.07).

2. The water-resistant UV paint according to claim 1, characterized in that, The content of the polyurethane acrylate is 30-50 parts by weight, the content of the monofunctional long-chain aliphatic diluent is 20-45 parts by weight, the content of the multifunctional diluent is 10-35 parts by weight, the content of the modified polysulfide is 4-8 parts by weight, the content of the photoinitiator is 1-5 parts by weight, the content of the carbodiimide anti-hydrolysis agent is 0.1-2 parts by weight, and the content of the auxiliary agent is 0-2 parts by weight.

3. The water-repellent UV paint according to claim 1 or 2, characterized in that, The modified polysulfide is prepared by the following method: S1, end-capping reaction of polyisocyanate and diamine to obtain isocyanate double-end-capped polyurea prepolymer; S2, addition reaction of the polyurea prepolymer obtained in step S1 and polysulfide compound in the presence of initiator to obtain the modified polysulfide.

4. The water-resistant UV paint according to claim 3, characterized in that, The molar ratio of the diamine, polyisocyanate and polysulfide compound is 1:(1.2-1.6):(0.2-1.6).

5. The water-resistant UV paint according to claim 3, characterized in that, The amount of the initiator is 0.1-0.3wt% of the total mass of the reaction raw materials.

6. The water-resistant UV paint according to claim 3, characterized in that, The thiol content of the modified polysulfide is 5-20wt%.

7. The water-resistant UV paint according to claim 3, characterized in that, The polyisocyanate is selected from at least one of toluene diisocyanate, norbornane diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate, 4,4-dicyclohexyl methane diisocyanate, pentamethylene diisocyanate and hexamethylene diisocyanate.

8. The water-resistant UV paint according to claim 3, characterized in that, The diamine is selected from at least one of ethylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, 1,5-pentylenediamine, 1,6-hexylenediamine, 1,7-heptylenediamine, 1,8-octylenediamine, 1,9-nonylenediamine and 1,10-decylenediamine.

9. The water-resistant UV paint according to claim 3, characterized in that, The polysulfide compound is a trifunctional and / or tetrafunctional polysulfide compound.

10. The water-resistant UV paint according to claim 3, characterized in that, The polythiol compound is selected from at least one of trimethylolpropane tri(3- mercaptoacetate), trimethylolpropane tri(3-mercaptopropionate), trimethylolpropane tri(3- mercaptobutyrate), pentaerythritol tetra(3-mercaptoacetate), pentaerythritol tetra(3- mercaptopropionate), and pentaerythritol tetra(3-mercaptobutyrate).

11. The water-resistant UV paint according to claim 1, characterized in that, The viscosity of the polyurethane acrylate at 25 DEG C is 1000-15000 cps.

12. The water-resistant UV paint according to claim 1, characterized in that, The functionality of the multifunctional diluent is 2-4.

13. The water-resistant UV paint according to claim 3, characterized in that, The multifunctional diluent is selected from 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 glyceryl triacrylate, tris(2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

14. The method of claim 1-13, wherein the method is characterized by, The method comprises mixing and stirring uniformly the polyurethane acrylate, the monofunctional long-chain aliphatic diluent, the multifunctional diluent, the modified polythiol, the photoinitiator, the carbodiimide-based hydrolysis-resistant agent, and the auxiliary agent, and then discharging under light protection to obtain the waterproof UV coating.

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