A kind of anti-ultraviolet water-based coating and preparation method thereof

Abstract

The invention discloses an anti-ultraviolet water-based coating and a preparation method thereof, and relates to the technical field of water-based coatings. An anti-ultraviolet water-based coating comprises the following raw materials in parts by weight: water-based epoxy resin emulsion: 80-100 parts, water-based curing agent: 30-50 parts, curing accelerator: 1-3 parts, dispersant: 1-2 parts, modified anti-ultraviolet agent: 2-3 parts, deionized water: 100-140 parts; the present invention prepares a first-generation polymer by urotropine and p-aminophenol, and then the first-generation polymer is grafted and copolymerized with glycidyl methacrylate and 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine to prepare a modified anti-ultraviolet agent. The anti-ultraviolet water-based coating prepared by the present invention has excellent anti-ultraviolet aging performance.

Description

Technical Field

[0001] The invention relates to the technical field of water-based coatings, and in particular to an anti-ultraviolet water-based coating and a preparation method thereof. Background Art

[0002] Epoxy resin is a type of polymer with excellent mechanical properties, high stability and good adhesion, and is widely used in the field of coatings. However, epoxy resin coatings generally have problems such as yellowing, gloss loss and decreased mechanical strength due to light aging. This is because the epoxy chain in the epoxy resin is easily broken under ultraviolet radiation, which eventually causes damage to the substrate.

[0003] A Chinese invention patent with publication number CN118421170A discloses an anti-aging water-based coating and a preparation method thereof. The patent prepares a new polymer by graft copolymerization of a first-generation polymer with glycidyl methacrylate and 2-(2H-benzotriazole-2-yl)-4-methyl-6-(2-propenyl)phenol, and then modifies the polymer with graphene oxide to obtain a modified antioxidant. In the patent, the modified antioxidant needs to be modified with graphene oxide to obtain better performance, and the steps are complicated and the cost is high. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide an anti-ultraviolet water-based coating and a preparation method thereof.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] An anti-ultraviolet water-based coating comprises the following raw materials in parts by weight:

[0007] Water-based epoxy resin emulsion: 80-100 parts,

[0008] Water-based curing agent: 30-50 parts,

[0009] Curing accelerator: 1-3 parts,

[0010] Dispersant: 1-2 parts,

[0011] Modified UV-resistant agent: 2-3 parts,

[0012] Deionized water: 100-140 parts;

[0013] The modified UV-resistant agent is prepared by the following method:

[0014] S1: Deionized water, hexamethylenetetramine, p-aminophenol and glacial acetic acid are added to the reactor in sequence, stirred and dissolved, heated to 65-70°C, reacted for 1-2h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times to obtain a first-generation polymer; the reaction equation is as follows:

[0015]

[0016] S2: Add DMF to the reactor, stir, raise the temperature to 95-105°C, add the first-generation polymer, glycidyl methacrylate, 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, catalyst C-94, 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 3-4 hours under nitrogen protection, cool to room temperature, add deionized water and stir evenly, centrifuge to obtain a polymer filter cake, wash with anhydrous ethanol and deionized water, and vacuum dry at 50-60°C to obtain a polymer; in this reaction, glycidyl methacrylate and 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine are grafted with the first-generation polymer through double bonds to obtain a modified UV inhibitor, and the reaction equation is as follows:

[0017]

[0018] Among them, m=o+p+q, m, o, p, q are natural numbers.

[0019] In step S1, the mass ratio of deionized water, hexamethylenetetramine, p-aminophenol and glacial acetic acid is 10:2.5:(1.0-1.2):(0.8-1.0).

[0020] In step S2, the feed mass ratio of DMF, first-generation polymer, glycidyl methacrylate, 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, catalyst C-94, and 1-butyl-3-methylimidazolium methane sulfonate ionic liquid is 50:(6-8):(5-7):(3-4):(0.1-0.15):(0.08-0.1).

[0021] The water-based curing agent is a phenolic modified fatty amine epoxy curing agent.

[0022] The curing accelerator is one of 2-ethyl-4-methylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol and isophoronediamine.

[0023] The dispersant is one of sodium lauryl sulfate, sodium tripolyphosphate and sodium secondary alkyl sulfonate.

[0024] A method for preparing an anti-ultraviolet water-based coating comprises the following steps:

[0025] Weigh by weight: 80-100 parts of waterborne epoxy resin emulsion, 30-50 parts of waterborne curing agent, 1-3 parts of curing accelerator, 1-2 parts of dispersant, 2-3 parts of modified UV-resistant agent, and 100-140 parts of deionized water;

[0026] Deionized water, water-based epoxy resin emulsion, dispersant, and modified UV-resistant agent are sequentially added into the stirrer and stirred for 10-30 minutes; then a water-based curing agent and a curing accelerator are added and stirred for 10-30 minutes to obtain UV-resistant water-based coating.

[0027] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0028] (1) The present invention prepares a first-generation polymer by using urotropine and p-aminophenol, and then grafts and copolymerizes the first-generation polymer with glycidyl methacrylate and 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine to prepare a modified UV-resistant agent for coatings to resist UV aging.

[0029] (2) The modified UV-resistant agent polymer prepared by the present invention contains epoxy groups provided by glycidyl methacrylate, which increases the compatibility of the modified UV-resistant agent and epoxy resin. 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine contains triazine groups and can be used as UV absorbers. The introduction of thienyl groups can not only broaden the absorption range but also increase the molar absorption coefficient. However, due to its small molecular weight, it is not resistant to migration. By grafting 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine onto the polymer, the molecular weight is increased and the migration resistance is improved. Therefore, adding the modified UV-resistant agent to the water-based coating improves the UV-resistant aging ability of the coating. DETAILED DESCRIPTION

[0030] The invention will be further described below in conjunction with the embodiments, but the invention is not limited to these embodiments.

[0031] Example 1 Preparation of modified UV-resistant agent:

[0032] S1: 100 g of deionized water, 25 g of urotropine, 10 g of p-aminophenol, and 8 g of glacial acetic acid were added to the reactor in sequence, stirred and dissolved, heated to 65°C, reacted for 2 h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times (50 g of deionized water each time) to obtain a first-generation polymer;

[0033] S2: Add 500g of DMF to the reactor, stir, raise the temperature to 95°C, add 60g of the first-generation polymer, 50g of glycidyl methacrylate, 30g of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, 1g of catalyst C-94, and 0.8g of 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 4h under nitrogen protection, cool to room temperature, add 400g of deionized water and stir evenly, centrifuge, then wash with 60g of anhydrous ethanol and then with 60g of deionized water, and dry under vacuum at 50°C for 10h to obtain a modified UV inhibitor.

[0034] Example 2 Preparation of modified UV-resistant agent:

[0035] S1: 100 g of deionized water, 25 g of urotropine, 11 g of p-aminophenol, and 9 g of glacial acetic acid were added to the reactor in sequence, stirred and dissolved, heated to 70°C, reacted for 1.5 h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times (50 g of deionized water each time) to obtain a first-generation polymer;

[0036] S2: Add 500g of DMF to the reactor, stir, raise the temperature to 100°C, add 70g of the first-generation polymer, 60g of glycidyl methacrylate, 35g of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, 1.25g of catalyst C-94, and 0.9g of 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 3.5h under nitrogen protection, cool to room temperature, add 400g of deionized water and stir evenly, centrifuge and filter, then wash with 60g of anhydrous ethanol and then with 60g of deionized water, and dry under vacuum at 55°C for 9h to obtain a modified UV inhibitor.

[0037] Example 3 Preparation of modified UV-resistant agent:

[0038] S1: 100 g of deionized water, 25 g of urotropine, 12 g of p-aminophenol, and 10 g of glacial acetic acid were added to the reactor in sequence, stirred and dissolved, heated to 70°C, reacted for 1 h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times (50 g of deionized water each time) to obtain a first-generation polymer;

[0039] S2: Add 500g of DMF to the reactor, stir, raise the temperature to 105°C, add 80g of the first-generation polymer, 70g of glycidyl methacrylate, 40g of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, 1.5g of catalyst C-94, and 1.0g of 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 3h under nitrogen protection, cool to room temperature, add 400g of deionized water and stir evenly, centrifuge, then wash with 60g of anhydrous ethanol and then with 60g of deionized water, and dry under vacuum at 60°C for 8h to obtain a modified UV inhibitor.

[0040] The 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine used in Example 1-3 was prepared in Example 4.

[0041] Example 4 Preparation of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine

[0042] Take 30g of 4,6-dithienyl-2-yl-2-(2,4-dihydroxy)phenyl-1,3,5-triazine, 12.9g of anhydrous potassium carbonate, 18g of 3-bromopropylene and 500ml of N,N-dimethylformamide and add them to a three-necked round-bottom flask, react at 100℃ for 12h, and stop the reaction. Add 200ml of deionized water to the reaction solution, then extract with 200ml of dichloromethane, wash the organic phase with 100ml of deionized water until pH=7~8, add 30g of anhydrous sodium sulfate and dry. Filter out the sodium sulfate, concentrate with a rotary evaporator, and separate by column chromatography to obtain 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine. The tested nuclear magnetic resonance hydrogen spectrum data is: 1 H NMR (300 MHz, DMSO- d 6) δ 9.63 (s, 1H), 7.85 – 7.67 (m, 5H), 7.25 (dd, J = 7.8, 5.0 Hz, 2H), 6.80 (dd, J = 9.1, 2.3 Hz, 1H), 6.58 (d, J = 2.3Hz, 1H), 6.00 (ddt, J = 16.9, 11.3, 5.6 Hz, 1H), 5.34 (ddt, J = 11.5, 2.4, 1.5Hz, 1H), 5.14 (ddt, J= 16.8, 2.4, 1.3 Hz, 1H), 4.40 (dt, J = 5.6, 1.4 Hz, 2H).

[0043] Example 5 Preparation of UV-resistant water-based coating:

[0044] (1) Weigh by weight: 800 g of water-based epoxy resin emulsion, 300 g of water-based curing agent (T31), 10 g of curing accelerator (2-ethyl-4-methylimidazole), 10 g of dispersant (sodium tripolyphosphate), 20 g of modified anti-ultraviolet agent (prepared in Example 1), and 1000 g of deionized water;

[0045] (2) At room temperature, deionized water, water-based epoxy resin emulsion, dispersant, and modified UV-resistant agent were added to the stirrer in sequence and stirred for 10 minutes; then, a water-based curing agent and a curing accelerator were added and stirred for 10 minutes to obtain a UV-resistant water-based coating.

[0046] Example 6 Preparation of UV-resistant water-based coating:

[0047] (1) Weigh by weight: water-based epoxy resin emulsion: 900 g, water-based curing agent (T31): 400 g, curing accelerator (2,4,6-tris(dimethylaminomethyl)phenol): 20 g, dispersant (sodium dodecyl sulfate): 15 g, modified anti-ultraviolet agent (prepared in Example 2): 25 g, deionized water: 1200 g;

[0048] (2) At room temperature, deionized water, water-based epoxy resin emulsion, dispersant, and modified UV-resistant agent were added to the stirrer in sequence and stirred for 20 minutes; then, a water-based curing agent and a curing accelerator were added and stirred for 20 minutes to obtain a UV-resistant water-based coating.

[0049] Example 7 Preparation of UV-resistant water-based coating

[0050] (1) Weigh by weight: water-based epoxy resin emulsion: 1000 g, water-based curing agent (T31): 500 g, curing accelerator (isophorone diamine): 30 g, dispersant (sodium secondary alkyl sulfonate): 20 g, modified anti-ultraviolet agent (prepared in Example 3): 30 g, deionized water: 1400 g;

[0051] (2) At room temperature, deionized water, water-based epoxy resin emulsion, dispersant, and modified UV-resistant agent were added to the stirrer in sequence and stirred for 30 minutes; then, a water-based curing agent and a curing accelerator were added and stirred for 30 minutes to obtain a UV-resistant water-based coating.

[0052] Comparative Example 1

[0053] A method for preparing an anti-ultraviolet water-based coating is substantially the same as that of Example 6, except that no modified anti-ultraviolet agent is added in step (2).

[0054] Comparative Example 2

[0055] A method for preparing an anti-ultraviolet water-based coating is substantially the same as that of Example 6, except that the modified anti-ultraviolet agent (prepared in Example 2) added in step (2) is replaced by an equal weight of UV-1577 (CAS No.: 147315-50-2).

[0056] Comparative Example 3

[0057] A method for preparing an anti-ultraviolet water-based coating is basically the same as that in Example 6, except that the modified anti-ultraviolet agent (prepared in Example 2) added in step (2) is replaced by 15 g of a first-generation polymer, 14 g of glycidyl methacrylate and 8 g of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine.

[0058] Comparative Example 4

[0059] The water-based epoxy resin coating was prepared using the raw materials and method of Example 5 in publication number CN118421170A.

[0060] Comparative Example 5

[0061] A method for preparing an anti-ultraviolet water-based coating is substantially the same as that of Example 6, except that the modified anti-ultraviolet agent (prepared in Example 2) added in step (2) is replaced by an equal weight of 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine.

[0062] Comparative Example 6

[0063] A method for preparing an anti-ultraviolet water-based coating is substantially the same as that of Example 6, except that the modified anti-ultraviolet agent (prepared in Example 2) added in step (2) is replaced by an antioxidant prepared by the following method:

[0064] S1: 100 g of deionized water, 25 g of urotropine, 11 g of p-aminophenol, and 9 g of glacial acetic acid were added to the reactor in sequence, stirred and dissolved, heated to 70°C, reacted for 1.5 h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times (50 g of deionized water each time) to obtain a first-generation polymer;

[0065] S2: Add 300g of DMF to the reactor, stir, raise the temperature to 100°C, add 80g of the first-generation polymer, 65g of glycidyl methacrylate, 35g of 2-(2H-benzotriazole-2-yl)-4-methyl-6-(2-propenyl)phenol, 1.2g of catalyst C-94, and 0.9g of 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 3.5h under nitrogen protection, cool to room temperature, add 400g of deionized water and stir evenly, obtain a polymer filter cake after centrifugal filtration, wash with 60g of anhydrous ethanol and then with 60g of deionized water, and dry in vacuo at 55°C for 9h to obtain a polymer antioxidant.

[0066] The water-based curing agent used in the examples and comparative examples of the present application is a phenolic modified fatty amine epoxy curing agent, model T31, produced by Henan Huineng Resin Co., Ltd.; the water-based epoxy resin emulsion used in Examples 5 and 7 is Y-1018 water-based epoxy resin emulsion, produced by Shanghai Wujing Chemical Technology Co., Ltd.; the water-based epoxy resin emulsion used in Example 6 is BS-2175 water-based epoxy resin emulsion, produced by Bath Synthetic New Materials (Shenzhen) Co., Ltd.

[0067] According to the requirements of the standard "Waterborne Epoxy Resin Anticorrosive Coatings" HG / T 4759-2014, the waterborne coating samples prepared in Examples 5-7 of the present application and Comparative Examples 1-5 and the aged samples were tested for salt spray resistance. The maximum time for each sample during the salt spray resistance test was 1000 h. The test results are shown in Table 1.

[0068] Sample aging method: The sample is continuously irradiated in a 1000W high-pressure mercury lamp ultraviolet aging box for 800 hours.

[0069] Table 1

[0070]

[0071] It can be seen from Table 1 that the water-based coating prepared in the present application had no blistering, cracking, peeling, or powdering at 1000 h before aging. After aging, Examples 5, 6, and 7 had no blistering, cracking, peeling, or powdering at 860, 890, and 880 h, respectively, and blistering began to be found at 870, 900, and 890 h.

[0072] Comparative Example 1 is a water-based coating prepared without adding modified anti-ultraviolet agent. After aging, blistering was found at 530h in the salt spray test. Comparative Example 2 is a comparative example using UV-1577 as an anti-ultraviolet agent. After aging, blistering was found at 700h in the salt spray test. Comparative Example 3 is a comparative example using first-generation polymer, glycidyl methacrylate and 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine as anti-ultraviolet agents. After aging, blistering was found at 660h in the salt spray test. Comparative Example 4 is prepared by the method of Example 5 in Publication No. CN118421170A. The water-based coating was found to have blistering at 890 hours in the salt spray test after aging; Comparative Example 5 is a comparative example using 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine as an anti-ultraviolet agent, and blistering was found at 730 hours in the salt spray test after aging; Comparative Example 6 is a water-based coating prepared by using the antioxidant disclosed in Publication No. CN118421170A without using graphene oxide modified, and blistering was found at 760 hours in the salt spray test after aging.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in the field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. An anti-ultraviolet water-based coating, characterized in that: The invention comprises the following raw materials in parts by weight: Water-based epoxy resin emulsion: 80-100 parts, Water-based curing agent: 30-50 parts, Curing accelerator: 1-3 parts, Dispersant: 1-2 parts, Modified UV-resistant agent: 2-3 parts, Deionized water: 100-140 parts; The modified UV-resistant agent is prepared by the following method: S1: Deionized water, hexamethylenetetramine, p-aminophenol and glacial acetic acid are added to the reactor in sequence, stirred and dissolved, heated to 65-70°C, reacted for 1-2h, cooled to room temperature to separate layers, removed the water layer, and washed with deionized water for 3 times to obtain a first-generation polymer; S2: Add DMF to the reactor, stir, raise the temperature to 95-105°C, add the first-generation polymer, glycidyl methacrylate, 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, catalyst C-94, and 1-butyl-3-methylimidazolium methane sulfonate ionic liquid in sequence, react for 3-4 hours under nitrogen protection, cool to room temperature, add deionized water and stir evenly, obtain a polymer filter cake after centrifugal filtration, wash with anhydrous ethanol and deionized water, and vacuum dry at 50-60°C to obtain a modified UV inhibitor; In step S1, the mass ratio of deionized water, hexamethylenetetramine, p-aminophenol and glacial acetic acid is 10:2.5:(1.0-1.2):(0.8-1.0); In step S2, the feed mass ratio of DMF, first-generation polymer, glycidyl methacrylate, 4,6-dithienyl-2-yl-2-(2-hydroxy-4-allyloxy)-phenyl-1,3,5-triazine, catalyst C-94, and 1-butyl-3-methylimidazolium methane sulfonate ionic liquid is 50:(6-8):(5-7):(3-4):(0.1-0.15):(0.08-0.1).

2. The anti-ultraviolet water-based coating according to claim 1, characterized in that: The water-based curing agent is a phenolic modified fatty amine epoxy curing agent.

3. The anti-ultraviolet water-based coating according to claim 1, characterized in that: The curing accelerator is one of 2-ethyl-4-methylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol and isophoronediamine.

4. The anti-ultraviolet water-based coating according to claim 1, characterized in that: The dispersant is one of sodium lauryl sulfate, sodium tripolyphosphate and sodium secondary alkyl sulfonate.

5. A method for preparing the anti-ultraviolet water-based coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Weigh by weight: 80-100 parts of waterborne epoxy resin emulsion, 30-50 parts of waterborne curing agent, 1-3 parts of curing accelerator, 1-2 parts of dispersant, 2-3 parts of modified UV-resistant agent, and 100-140 parts of deionized water; (2) Add deionized water, water-based epoxy resin emulsion, dispersant, and modified UV-resistant agent to the stirrer in sequence, and stir for 10-30 minutes; then add water-based curing agent and curing accelerator, and stir for 10-30 minutes to obtain UV-resistant water-based coating.

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