Preparation method of high-temperature-resistant waterproof ultraviolet light curing paint

Abstract

The application discloses a preparation method of high-temperature-resistant waterproof ultraviolet light curing paint, which comprises polyurethane acrylate, vinyl imide-based polymer, active diluent, photoinitiator, defoaming agent and film forming aid; the side chain of the vinyl imide-based polymer contains active alkenyl groups, which can be crosslinked and cured with the active diluent and the polyurethane acrylate under the action of the photoinitiator, so that the curing reaction process is promoted, and the light curing time is reduced. Moreover, the vinyl imide-based polymer contains high-modulus and high-temperature-resistant imine ring structure, and after being crosslinked and cured with the polyurethane acrylate, the binding force between the imide polymer molecular chain and the polyurethane is enhanced, and the hardness, toughness, water resistance and waterproof performance of the paint film are obviously improved. Meanwhile, the imide-based polymer has strong thermal stability, which is beneficial to improving the high-temperature resistance of the polyurethane paint and showing higher thermal decomposition temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a preparation method of a high-temperature-resistant waterproof ultraviolet curing coating. BACKGROUND

[0002] The ultraviolet curing coating mainly includes polyurethane acrylate, epoxy acrylate resin, etc., wherein the polyurethane acrylate has the advantages of good toughness, high mechanical strength, environmental friendliness, convenient construction, etc., and is widely applied. However, the traditional polyurethane acrylate has the problems of high water absorption, poor water resistance, and poor high-temperature resistance, and under high temperature, the mechanical properties of the coating film are greatly affected, and problems such as cracking and strength reduction are prone to occur.

[0003] The polyimide polymer is a polymer containing an imide ring structure, and has the advantages of high strength, strong water resistance, and good high-temperature resistance, and is well applied in polyurethane, phenolic resin, acrylic resin, etc. However, the compatibility between the polyimide and the polyurethane is poor, and when the polyurethane is directly added, the two are prone to problems such as interface incompatibility and phase separation, which affects the performance of the material. SUMMARY

[0004] The technical problem solved by the present application is to provide a preparation method of a high-temperature-resistant waterproof ultraviolet curing coating.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of a high-temperature-resistant waterproof ultraviolet curing coating, characterized in that the preparation method comprises the following steps:

[0006] Step (1), adding glutaraldehyde, 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraketone, and 4,4'-diaminodiphenylamine in a proportion of 1 mol:(0.7-0.95) mol:(0.05-0.3) mol into dimethyl sulfoxide, stirring and reacting at a temperature of 80-110°C for 18-24h, cooling in an ice water bath after the reaction, precipitating a precipitate, filtering, washing with ethanol, and drying to obtain an imide-based polymer; the preparation reaction formula is as follows:

[0007]

[0008] Step (2), adding the imide-based polymer into N,N-dimethylformamide, stirring and mixing uniformly, then adding 2-bromoethyl acrylate and a catalyst, stirring and reacting, adding distilled water to precipitate a precipitate, filtering, washing with ethanol, and drying to obtain a vinyl imide-based polymer; the reaction formula is as follows:

[0009]

[0010] Step (3), adding vinyl imide-based polymer, active diluent, photoinitiator, defoaming agent, film forming aid into polyurethane acrylate, mixing, obtaining high temperature resistant waterproof ultraviolet light curing coating.

[0011] Further, in (2), the ratio of imide-based polymer, 2-bromoethyl acrylate is 100g:(3.2-13)g.

[0012] Further, in (2), the catalyst is potassium carbonate, potassium hydroxide or sodium hydroxide.

[0013] Further, in (2), the reaction is carried out at a temperature of 50-120℃ for 24-48h.

[0014] Further, in (3), the ratio of polyurethane acrylate, vinyl imide-based polymer is 100g:(1-15)g.

[0015] Further, in (3), the active diluent includes 1,6-hexanediol diacrylate, tripropyleneglycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate.

[0016] Further, in (3), the photoinitiator includes photoinitiator TPO, photoinitiator 2959, photoinitiator 184.

[0017] The present application has the following technical effects: the present application uses glutaraldehyde, 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetrone, 4,4'-diamino diphenylamine as a polymer monomer, through Schiff base polymerization reaction, obtaining vinyl imide-based polymer, then under the action of potassium hydroxide and other catalysts, the diphenylamine group in the molecular main chain and 2-bromoethyl acrylate occur substitution reaction, obtaining vinyl imide-based polymer containing alkenyl in the side chain and imide ring structure in the main chain.

[0018] The present application adds vinyl imide-based polymer in polyurethane acrylate coating, under the action of photoinitiator, the vinyl imide-based polymer side chain contains active alkenyl group, which can occur crosslinking and curing reaction with active diluent and polyurethane acrylate, promoting the curing reaction process, which is conducive to reducing the photocuring time. And the vinyl imide-based polymer contains high modulus and high temperature resistant linear imide ring structure, after crosslinking and curing with polyurethane acrylate, the binding force between the imide polymer molecular chain and polyurethane is enhanced, which significantly improves the hardness, toughness and other mechanical properties of the paint film. At the same time, the imide-based polymer has strong thermal stability, which is conducive to improving the high temperature resistance of polyurethane coating, and showing higher thermal decomposition temperature.

[0019] After the vinylimide polymer of the present invention is cross-linked and cured with polyurethane acrylate, the cross-linking degree of the molecular chain of the polyurethane is increased, so that the cross-linked polyurethane has a very low water absorption rate at both room temperature and high temperature (80°C). The lower the water absorption rate, the better the water resistance and waterproof performance. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] The polyurethane acrylate of the present invention is EBECRYL 8807. The defoaming agent is BYK-A506.

[0022] The structural formula of 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraone is: The preparation method was carried out according to the method of the journal J. Mater. Chem., 2006, 16, 3466-3477, and the document "Combinatorial methods for the optimization of the vapordeposition of polyimide monomers and their polymerization" (DOI: 10.1039 / b606091a).

[0023] Example 1

[0024] To 80 mL of dimethyl sulfoxide were added 10 mmol of glutaraldehyde, 9.5 mmol of 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraone, and 0.5 mmol of 4,4'-diaminodiphenylamine. The mixture was stirred at 80°C for 18 hours. After the reaction, the mixture was cooled in an ice-water bath to precipitate the precipitate, which was filtered, washed with ethanol, and dried to obtain an imide polymer.

[0025] To 200 mL of N,N-dimethylformamide, 20 g of the imide polymer was added, and after stirring and mixing, 0.64 g of 2-bromoethyl acrylate and 1.16 g of potassium carbonate as a catalyst were added. The mixture was stirred and reacted at 120° C. for 48 h. Distilled water was added to precipitate the precipitate, which was filtered, washed with ethanol, and dried to obtain a vinylimide polymer.

[0026] To 2 kg polyurethane acrylate, add 20 g of vinyl imide-based polymer, 100 g of active diluent pentaerythritol triacrylate, 74 g of photoinitiator 184, 8 g of defoamer, 20 g of film-forming aid alcohol ester-12, mix well, and obtain a high-temperature-resistant waterproof ultraviolet curing paint.

[0027] Example 2

[0028] To 70 mL of dimethyl sulfoxide, add 10 mmol of glutaraldehyde, 9 mmol of 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraone, and 1 mmol of 4,4'-diaminodiphenylamine. Stir the reaction at a temperature of 110°C for 18 h. After the reaction, cool in an ice water bath, precipitate, filter, wash with ethanol, and dry to obtain an imide-based polymer.

[0029] To 250 mL of N,N-dimethylformamide, add 20 g of imide-based polymer. After stirring and mixing well, add 1.25 g of 2-bromoethyl acrylate and 0.83 g of catalyst sodium hydroxide. Stir the reaction at a temperature of 60°C for 24 h. Add distilled water to precipitate, filter, wash with ethanol, and dry to obtain a vinyl imide-based polymer.

[0030] To 2 kg of polyurethane acrylate, add 100 g of vinyl imide-based polymer, 90 g of active diluent trimethylolpropane triacrylate, 90 g of photoinitiator 2959, 15 g of defoamer, and 16 g of film-forming aid alcohol ester-12. Mix well to obtain a high-temperature-resistant waterproof ultraviolet curing paint.

[0031] Example 3

[0032] To 70 mL of dimethyl sulfoxide, add 10 mmol of glutaraldehyde, 8 mmol of 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraone, and 2 mmol of 4,4'-diaminodiphenylamine. Stir the reaction at a temperature of 80°C for 24 h. After the reaction, cool in an ice water bath, precipitate, filter, wash with ethanol, and dry to obtain an imide-based polymer.

[0033] To 300 mL of N,N-dimethylformamide, add 20 g of imide-based polymer. After stirring and mixing well, add 1.96 g of 2-bromoethyl acrylate and 1.32 g of catalyst sodium hydroxide. Stir the reaction at a temperature of 60°C for 36 h. Add distilled water to precipitate, filter, wash with ethanol, and dry to obtain a vinyl imide-based polymer.

[0034] To 2 kg polyurethane acrylate, 200 g of vinyl imide-based polymer, 75 g of active diluent tripropyleneglycol diacrylate, 76 g of photoinitiator 184, 5 g of defoamer, 20 g of film forming aid alcohol ester-12 were added and mixed to obtain a high temperature resistant waterproof ultraviolet light curing coating.

[0035] Example 4

[0036] To 50 mL of dimethyl sulfoxide, 10 mmol of glutaraldehyde, 7 mmol of 2,6-bis(4- aminophenyl)-benzo[1,2-C:4,5-C']dipyrryl-1,3,5,7(2H,6H)-tetraone, 3 mmol of 4,4'- diaminodiphenylamine were added, and stirred at a temperature of 90°C for 24 h. After the reaction, the precipitate was separated by cooling in an ice water bath, filtered, washed with ethanol and dried to obtain an imide-based polymer.

[0037] To 300 mL of N,N-dimethylformamide, 20 g of imide-based polymer was added, and after stirring and mixing, 2.6 g of 2-bromoethyl acrylate, 2.33 g of catalyst potassium hydroxide were added, and stirred at a temperature of 50°C for 36 h. Distilled water was added to precipitate the product, which was filtered, washed with ethanol and dried to obtain a vinyl imide-based polymer.

[0038] To 2 kg of polyurethane acrylate, 300 g of vinyl imide-based polymer, 60 g of active diluent 1,6-hexanediol diacrylate, 40 g of photoinitiator TPO, 15 g of defoamer, 18 g of film forming aid alcohol ester-12 were added and mixed to obtain a high temperature resistant waterproof ultraviolet light curing coating.

[0039] Comparative Example 1

[0040] To 2 kg of polyurethane acrylate, 100 g of active diluent pentaerythritol triacrylate, 74 g of photoinitiator 184, 8 g of defoamer, 20 g of film forming aid alcohol ester-12 were added and mixed to obtain a high temperature resistant waterproof ultraviolet light curing coating.

[0041] Comparative Example 2

[0042] To 80 mL of dimethyl sulfoxide, 10 mmol of glutaraldehyde, 9.5 mmol of 2,6-bis(4- aminophenyl)-benzo[1,2-C:4,5-C']dipyrryl-1,3,5,7(2H,6H)-tetraone, 0.5 mmol of 4,4'- diaminodiphenylamine were added, and stirred at a temperature of 80°C for 18 h. After the reaction, the precipitate was separated by cooling in an ice water bath, filtered, washed with ethanol and dried to obtain an imide-based polymer.

[0043] To 2 kg of polyurethane acrylate, add 20 g of imide-based polymer, 100 g of active diluent pentaerythritol triacrylate, 74 g of photoinitiator 184, 8 g of defoamer, 20 g of film-forming aid alcohol ester-12, mix well, and obtain a high-temperature-resistant waterproof UV-curable coating.

[0044] Pour the coating on the surface of the tinplate, and irradiate and cure in a 300 W UV curing machine. The photocuring time is determined by GB / T 1728-2020 standard, using the blade method. The hardness is determined according to GB / T 6739-2022 standard. The flexibility is determined according to GB / T 1731-2020 standard. The test results are shown in the table below.

[0045]

[0046] Pour the coating into a mold, irradiate and cure in a 300 W UV curing machine for 180 min, and then cut into a sample of 2 cm x 2 cm x 0.2 cm. The thermal performance of the sample is tested by a thermal gravimetric analyzer. The nitrogen atmosphere, the heating rate is 10 ℃ / min. 5% T is the temperature when the mass loss is 5%. T 50% T is the temperature when the mass loss is 50%. The test results are shown in the table below.

[0047]

[0048] The sample is made into a sample of 5 cm x 5 cm x 0.5 cm, weighed, and then immersed in distilled water at 25 ℃ and 80 ℃, respectively, for 48 h. The sample is taken out, the surface water is absorbed with filter paper, weighed, and the water absorption rate is calculated. The water absorption rate = (m-m0) / m0 x 100%, m is the mass after water absorption, and m0 is the mass before water absorption. The test results are shown in the table below.

[0049]

[0050] After testing, the polyurethane acrylate coating in examples 1-4 added with the vinyl imide-based polymer, under the action of the photoinitiator, the vinyl imide-based polymer side chain contains active alkenyl groups, which can crosslink and cure with active diluent, polyurethane acrylate, promote the curing reaction process, and is conducive to reducing the photocuring time; and the vinyl imide-based polymer contains a high modulus and high temperature resistant phenylimine ring structure ( ), after cross-linking and curing with polyurethane acrylate, the bonding between the imide polymer molecular chains and the polyurethane is strengthened, significantly improving the hardness, toughness, and other mechanical properties of the paint film. Furthermore, the imide polymer has strong thermal stability, which helps improve the high-temperature resistance of polyurethane coatings and exhibits a higher thermal decomposition temperature. Furthermore, after cross-linking and curing with the vinylimide polymer and polyurethane acrylate, the degree of cross-linking of the polyurethane molecular chains is increased, resulting in very low water absorption at both room temperature and high temperature (80°C). The lower the water absorption, the better the water resistance and waterproofing properties.

[0051] Comparative Example 1 does not contain vinylimide polymer, and the polyurethane acrylate paint film has low hardness and poor flexibility. It also has high water absorption, poor water and water resistance, low thermal decomposition stability, and poor high temperature resistance.

[0052] The imide polymer added in Comparative Example 2 does not contain an olefinic group and cannot undergo crosslinking and curing with the polyurethane acrylate and reactive diluent. The light curing time is long, the paint film has low hardness and poor flexibility, and the water absorption rate is high, resulting in poor water resistance and waterproofing.

Claims

1. A method for preparing a high temperature resistant and waterproof UV curing coating, characterized in that: The preparation method is: Step (1), adding glutaraldehyde, 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraketone, and 4,4'-diaminodiphenylamine to dimethyl sulfoxide, stirring to react, cooling in an ice-water bath after the reaction, precipitating a precipitate, filtering, washing with ethanol, and drying to obtain an imide polymer; Step (2), adding an imide polymer to N,N-dimethylformamide, stirring and mixing, then adding 2-bromoethyl acrylate and a catalyst, stirring to react, adding distilled water to precipitate, filtering, washing with ethanol and drying to obtain a vinylimide polymer; Step (3), adding vinylimide polymer, reactive diluent, photoinitiator, defoaming agent, and film-forming aid to polyurethane acrylate, mixing, and obtaining a high temperature resistant and waterproof UV curing coating; In the step (1), the ratio of glutaraldehyde, 2,6-bis(4-aminophenyl)-benzo[1,2-C:4,5-C']dipyrrole-1,3,5,7(2H,6H)-tetraone, and 4,4'-diaminodiphenylamine is 1 mol: (0.7-0.95) mol: (0.05-0.3) mol.

2. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (1), the reaction is carried out at a temperature of 80-110° C. for 18-24 hours.

3. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (2), the ratio of the imide polymer to 2-bromoethyl acrylate is 100 g: (3.2-13) g.

4. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, wherein: In the step (2), the catalyst is potassium carbonate, potassium hydroxide or sodium hydroxide.

5. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (2), the reaction is carried out at a temperature of 50-120° C. for 24-48 hours.

6. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (3), the ratio of polyurethane acrylate to vinylimide polymer is 100 g: (1-15) g.

7. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (3), the active diluent includes 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, pentaerythritol triacrylate or trimethylolpropane triacrylate.

8. The method for preparing the high temperature resistant and waterproof UV curing coating according to claim 1, characterized in that: In the step (3), the photoinitiator includes photoinitiator TPO, photoinitiator 2959 or photoinitiator 184.

Images