Polyurethane coating with sufficient tack-free dryness and preparation method therefor

Abstract

The present invention relates to the technical field of polyurethane coatings, and in particular to a polyurethane coating with sufficient tack-free dryness and a preparation method therefor. In the present invention, ethylene glycol, potassium methoxide, and glycidol are used to prepare a branched polyglycidyl ether and silicon dioxide is modified using the branched polyglycidyl ether. The addition of the branched polyglycidyl ether improves the compatibility of the modified silicon dioxide in a modified polyurethane emulsion, thereby enhancing the hydrophobicity and corrosion resistance of the coating. The backbone of the branched polyglycidyl ether has a high molecular weight, providing a large number of crosslinking sites, and by adding the branched polyglycidyl ether-modified silicon dioxide to the polyurethane coating, the water resistance of the polyurethane coating is enhanced. In the present invention, benzotriazole is also loaded on the silicon dioxide as a corrosion inhibitor, thereby imparting a corrosion-resistant effect to the coating.

Description

A fully surface-dried polyurethane coating and its preparation method Technical Field

[0001] This invention relates to the field of polyurethane coating technology, specifically to a polyurethane coating with sufficient surface drying and its preparation method. Background Technology

[0002] Currently, in addition to traditional functions such as heat insulation and one-way vision, more and more companies are focusing on developing iridescent car films, primarily for windshields. The various colors displayed by iridescent car films are mainly created by applying iridescent pigments to a polyurethane film.

[0003] However, during the current laboratory preparation of iridescent films, it was found that the finished films were prone to whitening and fogging, resulting in a weak color rendering effect. It was later discovered that this was due to insufficient surface drying of the polyurethane film coating after application, which needs to be improved.

[0004] To address the aforementioned issues and ensure that the polyurethane film coating achieves sufficient surface drying and good hydrophobicity after application, this invention provides a polyurethane coating with sufficient surface drying and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a polyurethane coating with sufficient surface drying and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a fully surface-dried polyurethane coating includes the following steps:

[0008] Step 1: Take ethylene glycol and potassium methoxide, stir under vacuum at 70-72℃ for 30-40 min, then heat to 155-157℃ under nitrogen protection, then add 8g glycidyl ether dropwise, and react for 16-17 h to obtain branched polyglycidyl ether.

[0009] Step 2: Take silica loaded with corrosion inhibitor and N,N-dimethylformamide, and disperse them by ultrasonication to obtain silica dispersion; take branched polyglycidyl ether and N,N-dimethylformamide, disperse them by ultrasonication, add silica dispersion, disperse by ultrasonication for 30-40 min, then stir for 22-26 h, wash and dry to obtain modified silica;

[0010] Step 3: Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0011] More preferably, the polyurethane coating comprises the following components by weight: 20-30 parts polyurethane emulsion, 10-15 parts modified polyurethane emulsion, 20-30 parts waterborne acrylic emulsion, 2-4 parts ink, 6-8 parts cyclopentanone, 2-3 parts photoinitiator, 2-3 parts leveling agent, and 6-9 parts modified silica.

[0012] A more optimized method for preparing the polyurethane emulsion is as follows: take polypropylene glycol and isophorone diisocyanate, stir at 80-85℃ for 2-3 hours, add 2,2-dimethylolpropionic acid and acetone, heat to 100℃ and react for 70-90 minutes, then cool to 30-35℃, add triethylamine, react for 30-40 minutes, add deionized water, stir for 30-40 minutes, and obtain the polyurethane emulsion.

[0013] A more optimized method for preparing the modified polyurethane emulsion is as follows: Take polyether polyol, single-terminated dihydroxyl organosilicon prepolymer, and 2,2-bis(hydroxymethyl)propionic acid, stir until homogeneous, add isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 88-92℃, react for 3-4 hours, cool to 70-72℃, add ethylene glycol solution, react for 2-2.5 hours, heat to 82-85℃, add branched polyglycidyl ether solution, react for 2-3 hours, add modified sodium alginate and 1H,1H,2H,2H-perfluorooctanol, react for 3-4 hours, add 2g triethylamine, stir for 3-4 minutes, and rotary evaporate to obtain the modified polyurethane emulsion.

[0014] A more optimized method for preparing the modified sodium alginate is as follows: Sodium alginate and deionized water are taken, stirred evenly, sodium periodate aqueous solution is added, and the mixture is reacted under light-protected conditions for 4-5 hours. Ethylene glycol is added, stirred evenly, dialyzed, and freeze-dried to obtain oxidized sodium alginate; Cinnamamide and ethanol are taken, stirred evenly to obtain cinnamamide solution; Sodium alginate oxide and deionized water are taken, stirred evenly, cinnamamide solution is added dropwise, and the mixture is reacted at 50-55℃ for 4-5 hours. The mixture is dialyzed and freeze-dried to obtain modified sodium alginate.

[0015] A more optimized method for preparing the silica loaded with corrosion inhibitor is as follows: take emulsifier, cyclohexane, and ammonia, stir evenly to obtain mixture A; take benzotriazole and deionized water, stir evenly to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 30-40 min, heat to 35-40℃, add tetraethyl orthosilicate, react for 22-26 h, wash and dry to obtain silica loaded with corrosion inhibitor.

[0016] More preferably, the leveling agent is any one or more of BYK354 leveling agent and BYK320 leveling agent.

[0017] More preferably, the photoinitiator is selected from one or more of 1-hydroxycyclohexylphenyl ketone and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] (1) This invention uses ethylene glycol, potassium methoxide, and glycidyl ether to prepare a branched polyglycidyl ether, which is then used to modify silica. The addition of branched polyglycidyl ether improves the compatibility of modified silica in modified polyurethane emulsion, thereby enhancing the hydrophobicity and corrosion resistance of the coating. The high molecular weight of the branched polyglycidyl ether backbone provides a large number of crosslinking sites. Adding branched polyglycidyl ether-modified silica to polyurethane coatings enhances the water resistance of polyurethane coatings. This invention also loads benzotriazole onto silica as a corrosion inhibitor, giving the coating a corrosion-resistant effect.

[0020] (2) This invention uses polyether polyol and single-terminated dihydroxyl organosilicon prepolymer to prepare a modified polyurethane emulsion. 1H,1H,2H,2H-perfluorooctanol is used to improve the hydrophobicity of the polyurethane emulsion, and modified sodium alginate is added for further modification. This invention uses sodium periodate to oxidize sodium alginate, and then uses cinnamamide to graft the treated sodium alginate to obtain modified sodium alginate with good hydrophobicity. The modified sodium alginate also has double bonds, which can increase the degree of crosslinking and accelerate the crosslinking reaction of the polyurethane film, thereby accelerating the surface drying speed of the polyurethane coating. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] There are no special restrictions on the manufacturers from which the substances involved in this invention can be purchased. Exemplary examples include: polypropylene glycol: model: PPG-2000, which can be purchased from Nantong Boya Environmental Protection Technology Co., Ltd.; polyurethane acrylate: model: L-6205D, which can be purchased from Guangdong Lankeru New Materials Co., Ltd.; polyether polyol: model: N220, which can be purchased from Aladdin; single-terminated dihydroxyl organosilicon prepolymer: model: 8822F2, which can be purchased from Guangzhou Sloco Co., Ltd.; ink: model: BL-3020, which can be purchased from Zhongshan Liyang Nanotechnology Co., Ltd.; and water-based acrylic emulsion: model: 1025, which can be purchased from Xinlian Chemical Co., Ltd.

[0023] Example 1: A method for preparing a fully surface-dried polyurethane coating, comprising the following steps:

[0024] Step 1: Preparation of polyurethane emulsion:

[0025] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 83℃ for 2.5h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 80min, then cool to 32℃, add 0.1g of triethylamine, react for 35min, add 15mL of deionized water, stir for 35min to obtain polyurethane emulsion;

[0026] Step 2: Preparation of modified sodium alginate:

[0027] Take 0.6g of sodium alginate and 500mL of deionized water, stir well, add 5.5g of 10% sodium periodate aqueous solution, react under light-protected conditions for 4.5h, add 0.5g of ethylene glycol, stir well, dialyze, and freeze dry to obtain oxidized sodium alginate; take 13g of cinnamamide and 100mL of ethanol, stir well to obtain cinnamamide solution; take 0.6g of oxidized sodium alginate and 50mL of deionized water, stir well, add 8g of cinnamamide solution dropwise, react at 52℃ for 4.5h, dialyze, and freeze dry to obtain modified sodium alginate;

[0028] Step 3: Preparation of branched polyglycidyl ether:

[0029] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 71℃ for 35min, then heat to 156℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 16.5h to obtain branched polyglycidyl ether.

[0030] Step 4: Preparation of modified polyurethane emulsion:

[0031] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 90℃, react for 3.5h, cool to 71℃, add ethylene glycol solution, react for 2.2h, heat to 83℃, add 2g of branched polyglycidyl ether solution, react for 2.5h, add 0.8g of modified sodium alginate and 5g of 1H,1H,2H,2H-perfluorooctanol, react for 3.5h, add 2g of triethylamine, stir for 3.5min, and rotary evaporate to obtain modified polyurethane emulsion;

[0032] Step 5: Preparation of silica loaded with corrosion inhibitor:

[0033] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 35min, heat to 37℃, add 30mL of tetraethyl orthosilicate, react for 24h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0034] Step Six: Preparation of Modified Silica:

[0035] Take 2g of silica loaded with corrosion inhibitor and 100mL of N,N-dimethylformamide, and disperse them by ultrasonication to obtain a silica dispersion; take 10g of branched polyglycidyl ether and 50mL of N,N-dimethylformamide, disperse them by ultrasonication, add the silica dispersion, disperse by ultrasonication for 35min, then stir for 24h, wash and dry to obtain modified silica.

[0036] Step 7: Preparation of polyurethane coating:

[0037] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0038] The polyurethane coating comprises the following components by weight: 25 parts polyurethane emulsion, 12 parts modified polyurethane emulsion, 25 parts water-based acrylic emulsion, 3 parts ink, 7 parts cyclopentanone, 2.5 parts photoinitiator, 2.5 parts leveling agent, and 7 parts modified silica.

[0039] Example 2: A method for preparing a fully surface-dried polyurethane coating, comprising the following steps:

[0040] Step 1: Preparation of polyurethane emulsion:

[0041] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 80℃ for 2h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 70min, then cool to 30℃, add 0.1g of triethylamine, react for 30min, add 15mL of deionized water, stir for 30min to obtain polyurethane emulsion;

[0042] Step 2: Preparation of modified sodium alginate:

[0043] Take 0.6g of sodium alginate and 500mL of deionized water, stir well, add 5.5g of 10% sodium periodate aqueous solution, react for 4h under light-protected conditions, add 0.5g of ethylene glycol, stir well, dialyze, and freeze dry to obtain oxidized sodium alginate; take 13g of cinnamamide and 100mL of ethanol, stir well to obtain cinnamamide solution; take 0.6g of oxidized sodium alginate and 50mL of deionized water, stir well, add 8g of cinnamamide solution dropwise, react at 50℃ for 4h, dialyze, and freeze dry to obtain modified sodium alginate;

[0044] Step 3: Preparation of branched polyglycidyl ether:

[0045] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 70℃ for 30min, then heat to 155℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 16h to obtain branched polyglycidyl ether.

[0046] Step 4: Preparation of modified polyurethane emulsion:

[0047] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 88℃, react for 3h, cool to 70℃, add ethylene glycol solution, react for 2h, heat to 82℃, add 2g of branched polyglycidyl ether solution, react for 2h, add 0.8g of modified sodium alginate and 5g of 1H,1H,2H,2H-perfluorooctanol, react for 3h, add 2g of triethylamine, stir for 3min, and rotary evaporate to obtain modified polyurethane emulsion;

[0048] Step 5: Preparation of silica loaded with corrosion inhibitor:

[0049] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 30min, heat to 35℃, add 30mL of tetraethyl orthosilicate, react for 22h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0050] Step Six: Preparation of Modified Silica:

[0051] Take 2g of silica loaded with corrosion inhibitor and 100mL of N,N-dimethylformamide, and disperse them by ultrasonication to obtain a silica dispersion; take 10g of branched polyglycidyl ether and 50mL of N,N-dimethylformamide, disperse them by ultrasonication, add the silica dispersion, disperse by ultrasonication for 30min, then stir for 22h, wash and dry to obtain modified silica.

[0052] Step 7: Preparation of polyurethane coating:

[0053] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0054] The polyurethane coating comprises the following components by weight: 20 parts polyurethane emulsion, 10 parts modified polyurethane emulsion, 20 parts water-based acrylic emulsion, 2 parts ink, 6 parts cyclopentanone, 2 parts photoinitiator, 2 parts leveling agent, and 6 parts modified silica.

[0055] Example 3: A method for preparing a fully surface-dried polyurethane coating, comprising the following steps:

[0056] Step 1: Preparation of polyurethane emulsion:

[0057] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 85℃ for 3h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 90min, then cool to 35℃, add 0.1g of triethylamine, react for 40min, add 15mL of deionized water, stir for 40min to obtain polyurethane emulsion;

[0058] Step 2: Preparation of modified sodium alginate:

[0059] Take 0.6g of sodium alginate and 500mL of deionized water, stir well, add 5.5g of 10% sodium periodate aqueous solution, react for 5h under light-protected conditions, add 0.5g of ethylene glycol, stir well, dialyze and freeze dry to obtain oxidized sodium alginate; take 13g of cinnamamide and 100mL of ethanol, stir well to obtain cinnamamide solution; take 0.6g of oxidized sodium alginate and 50mL of deionized water, stir well, add 8g of cinnamamide solution dropwise, react at 55℃ for 5h, dialyze and freeze dry to obtain modified sodium alginate;

[0060] Step 3: Preparation of branched polyglycidyl ether:

[0061] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 72℃ for 40min, then heat to 157℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 17h to obtain branched polyglycidyl ether.

[0062] Step 4: Preparation of modified polyurethane emulsion:

[0063] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 92℃, react for 4h, cool to 72℃, add ethylene glycol solution, react for 2.5h, heat to 85℃, add 2g of branched polyglycidyl ether solution, react for 3h, add 0.8g of modified sodium alginate and 5g of 1H,1H,2H,2H-perfluorooctanol, react for 4h, add 2g of triethylamine, stir for 4min, and rotary evaporate to obtain modified polyurethane emulsion;

[0064] Step 5: Preparation of silica loaded with corrosion inhibitor:

[0065] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 40min, heat to 40℃, add 30mL of tetraethyl orthosilicate, react for 26h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0066] Step Six: Preparation of Modified Silica:

[0067] Take 2g of silica loaded with corrosion inhibitor and 100mL of N,N-dimethylformamide, and disperse them by ultrasonication to obtain a silica dispersion; take 10g of branched polyglycidyl ether and 50mL of N,N-dimethylformamide, disperse them by ultrasonication, add the silica dispersion, disperse by ultrasonication for 40min, then stir for 26h, wash and dry to obtain modified silica.

[0068] Step 7: Preparation of polyurethane coating:

[0069] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0070] The polyurethane coating comprises the following components by weight: 30 parts polyurethane emulsion, 15 parts modified polyurethane emulsion, 30 parts water-based acrylic emulsion, 4 parts ink, 8 parts cyclopentanone, 3 parts photoinitiator, 3 parts leveling agent, and 9 parts modified silica.

[0071] Comparative Example 1: No branched polyglycidyl ether was used to modify silica; all other aspects were the same as in Example 1.

[0072] Step 1: Preparation of polyurethane emulsion:

[0073] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 83℃ for 2.5h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 80min, then cool to 32℃, add 0.1g of triethylamine, react for 35min, add 15mL of deionized water, stir for 35min to obtain polyurethane emulsion;

[0074] Step 2: Preparation of modified sodium alginate:

[0075] Take 0.6g of sodium alginate and 500mL of deionized water, stir well, add 5.5g of 10% sodium periodate aqueous solution, react under light-protected conditions for 4.5h, add 0.5g of ethylene glycol, stir well, dialyze, and freeze dry to obtain oxidized sodium alginate; take 13g of cinnamamide and 100mL of ethanol, stir well to obtain cinnamamide solution; take 0.6g of oxidized sodium alginate and 50mL of deionized water, stir well, add 8g of cinnamamide solution dropwise, react at 52℃ for 4.5h, dialyze, and freeze dry to obtain modified sodium alginate;

[0076] Step 3: Preparation of branched polyglycidyl ether:

[0077] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 71℃ for 35min, then heat to 156℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 16.5h to obtain branched polyglycidyl ether.

[0078] Step 4: Preparation of modified polyurethane emulsion:

[0079] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 90℃, react for 3.5h, cool to 71℃, add ethylene glycol solution, react for 2.2h, heat to 83℃, add 2g of branched polyglycidyl ether solution, react for 2.5h, add 0.8g of modified sodium alginate and 5g of 1H,1H,2H,2H-perfluorooctanol, react for 3.5h, add 2g of triethylamine, stir for 3.5min, and rotary evaporate to obtain modified polyurethane emulsion;

[0080] Step 5: Preparation of silica loaded with corrosion inhibitor:

[0081] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 35min, heat to 37℃, add 30mL of tetraethyl orthosilicate, react for 24h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0082] Step Six: Preparation of Polyurethane Coating:

[0083] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0084] The polyurethane coating comprises the following components by weight: 25 parts polyurethane emulsion, 12 parts modified polyurethane emulsion, 25 parts water-based acrylic emulsion, 3 parts ink, 7 parts cyclopentanone, 2.5 parts photoinitiator, 2.5 parts leveling agent, and 7 parts modified silica.

[0085] Comparative Example 2: No modified sodium alginate was added; all other aspects were the same as in Example 1.

[0086] Step 1: Preparation of polyurethane emulsion:

[0087] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 83℃ for 2.5h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 80min, then cool to 32℃, add 0.1g of triethylamine, react for 35min, add 15mL of deionized water, stir for 35min to obtain polyurethane emulsion;

[0088] Step 2: Preparation of branched polyglycidyl ether:

[0089] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 71℃ for 35min, then heat to 156℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 16.5h to obtain branched polyglycidyl ether.

[0090] Step 3: Preparation of modified polyurethane emulsion:

[0091] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 90℃, react for 3.5h, cool to 71℃, add ethylene glycol solution, react for 2.2h, heat to 83℃, add 2g of branched polyglycidyl ether solution, react for 2.5h, add 5g of 1H,1H,2H,2H-perfluorooctanol, react for 3.5h, add 2g of triethylamine, stir for 3.5min, and rotary evaporate to obtain modified polyurethane emulsion;

[0092] Step 4: Preparation of silica loaded with corrosion inhibitor:

[0093] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 35min, heat to 37℃, add 30mL of tetraethyl orthosilicate, react for 24h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0094] Step 5: Preparation of modified silica:

[0095] Take 2g of silica loaded with corrosion inhibitor and 100mL of N,N-dimethylformamide, and disperse them by ultrasonication to obtain a silica dispersion; take 10g of branched polyglycidyl ether and 50mL of N,N-dimethylformamide, disperse them by ultrasonication, add the silica dispersion, disperse by ultrasonication for 35min, then stir for 24h, wash and dry to obtain modified silica.

[0096] Step Six: Preparation of Polyurethane Coating:

[0097] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0098] The polyurethane coating comprises the following components by weight: 25 parts polyurethane emulsion, 12 parts modified polyurethane emulsion, 25 parts water-based acrylic emulsion, 3 parts ink, 7 parts cyclopentanone, 2.5 parts photoinitiator, 2.5 parts leveling agent, and 7 parts modified silica.

[0099] Comparative Example 3: Without the addition of 1H, 1H, 2H, 2H-perfluorooctanol, the rest was the same as in Example 1:

[0100] Step 1: Preparation of polyurethane emulsion:

[0101] Take 1g of polypropylene glycol and 22g of isophorone diisocyanate, stir at 83℃ for 2.5h, add 0.1g of 2,2-dimethylolpropionic acid and 12g of acetone, heat to 100℃ and react for 80min, then cool to 32℃, add 0.1g of triethylamine, react for 35min, add 15mL of deionized water, stir for 35min to obtain polyurethane emulsion;

[0102] Step 2: Preparation of modified sodium alginate:

[0103] Take 0.6g of sodium alginate and 500mL of deionized water, stir well, add 5.5g of 10% sodium periodate aqueous solution, react under light-protected conditions for 4.5h, add 0.5g of ethylene glycol, stir well, dialyze, and freeze dry to obtain oxidized sodium alginate; take 13g of cinnamamide and 100mL of ethanol, stir well to obtain cinnamamide solution; take 0.6g of oxidized sodium alginate and 50mL of deionized water, stir well, add 8g of cinnamamide solution dropwise, react at 52℃ for 4.5h, dialyze, and freeze dry to obtain modified sodium alginate;

[0104] Step 3: Preparation of branched polyglycidyl ether:

[0105] Take 6g of ethylene glycol and 0.5g of potassium methoxide, stir under vacuum at 71℃ for 35min, then heat to 156℃ under nitrogen protection, then add 8g of glycidyl ether dropwise, and react for 16.5h to obtain branched polyglycidyl ether.

[0106] Step 4: Preparation of modified polyurethane emulsion:

[0107] Take 27g of polyether polyol N220, 2.5g of single-terminated dihydroxy organosilicon prepolymer, and 2.8g of 2,2-bis(hydroxymethyl)propionic acid, stir evenly, add 15g of isophorone diisocyanate, add two drops of dibutyltin dilaurate, heat to 90℃, react for 3.5h, cool to 71℃, add ethylene glycol solution, react for 2.2h, heat to 83℃, add 2g of branched polyglycidyl ether solution, react for 2.5h, add 0.8g of modified sodium alginate, react for 3.5h, add 2g of triethylamine, stir for 3.5min, and rotary evaporate to obtain modified polyurethane emulsion;

[0108] Step 5: Preparation of silica loaded with corrosion inhibitor:

[0109] Take 9g of emulsifier OP-10, 120mL of cyclohexane, and 3mL of ammonia water, and stir until homogeneous to obtain mixture A; take 2g of benzotriazole and 150mL of deionized water, and stir until homogeneous to obtain mixture B; add mixture B dropwise to mixture A while stirring continuously, stir for 35min, heat to 37℃, add 30mL of tetraethyl orthosilicate, react for 24h, wash and dry to obtain silica loaded with corrosion inhibitor;

[0110] Step Six: Preparation of Modified Silica:

[0111] Take 2g of silica loaded with corrosion inhibitor and 100mL of N,N-dimethylformamide, and disperse them by ultrasonication to obtain a silica dispersion; take 10g of branched polyglycidyl ether and 50mL of N,N-dimethylformamide, disperse them by ultrasonication, add the silica dispersion, disperse by ultrasonication for 35min, then stir for 24h, wash and dry to obtain modified silica.

[0112] Step 7: Preparation of polyurethane coating:

[0113] Take polyurethane emulsion, modified polyurethane emulsion, and water-based acrylic emulsion, stir them evenly to obtain a mixed emulsion; take ink and cyclopentanone, stir them evenly, add photoinitiator, mixed emulsion, leveling agent, and modified silica, stir evenly to obtain polyurethane coating.

[0114] The polyurethane coating comprises the following components by weight: 25 parts polyurethane emulsion, 12 parts modified polyurethane emulsion, 25 parts water-based acrylic emulsion, 3 parts ink, 7 parts cyclopentanone, 2.5 parts photoinitiator, 2.5 parts leveling agent, and 7 parts modified silica.

[0115] experiment:

[0116] The polyurethane coatings prepared in Examples 1-3 and Comparative Examples 1-3 were sprayed and cured into films. Performance tests were then conducted according to GB / T19250-2013. The spray thickness of the polyurethane coating was 0.5 mm. Surface drying time was tested, and the water contact angle was measured using a DSA255 contact angle meter. The coatings were immersed in a saturated calcium hydroxide aqueous solution for 24 hours according to GB / T9756-2018. The surface condition of the coatings was observed to characterize their alkali resistance. The data obtained are shown in the table below.

[0117]

[0118] Conclusions: The data comparison in the table shows that in Comparative Example 1, without branched polyglycidyl ether modification of silica, the degree of crosslinking decreased, resulting in a longer surface drying time and worse hydrophobicity of the polyurethane coating. The compatibility of modified silica in the modified polyurethane emulsion also deteriorated, leading to poorer corrosion resistance of the coating. In Comparative Example 2, without the addition of modified sodium alginate, the degree of crosslinking of the polyurethane film decreased, and the surface drying speed of the polyurethane coating slowed down. In Comparative Example 3, without the addition of 1H,1H,2H,2H-perfluorooctanoic acid, the hydrophobicity and corrosion resistance of the polyurethane coating worsened.

[0119] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of a fully air-dried polyurethane coating, characterized in that: It comprises the following steps: Step one: take ethylene glycol, potassium methoxide, stir under vacuum condition at 70-72℃ for 30-40min, then heat to 155-157℃ under nitrogen protection, then add 8g glycidol dropwise, react for 16-17h to obtain branched polyglycidyl ether; Step two: take the corrosion inhibitor loaded silica and N,N-dimethylformamide, ultrasonic dispersion to obtain silica dispersion liquid; take branched polyglycidyl ether and N,N-dimethylformamide, ultrasonic dispersion, add silica dispersion liquid, ultrasonic dispersion for 30-40min, then stir for 22-26h, wash, dry to obtain modified silica; Step three: take polyurethane emulsion, modified polyurethane emulsion, water-based acrylic emulsion, stir uniformly to obtain mixed emulsion; take ink and cyclopentanone, stir uniformly, add photoinitiator, mixed emulsion, leveling agent, modified silica, stir uniformly to obtain polyurethane coating.

2. A process for the preparation of a fully-sintered polyurethane coating according to claim 1, characterized in that: The polyurethane coating comprises the following ingredients by weight: 20-30 parts of polyurethane emulsion, 10-15 parts of modified polyurethane emulsion, 20-30 parts of water-based acrylic emulsion, 2-4 parts of ink, 6-8 parts of cyclopentanone, 2-3 parts of photoinitiator, 2-3 parts of leveling agent, and 6-9 parts of modified silica.

3. A process for the preparation of a fully-sintered polyurethane coating according to claim 2, characterized in that: The preparation method of the polyurethane emulsion is as follows: take polypropylene glycol and isophorone diisocyanate, stir at 80-85℃ for 2-3h, add 2,2-dimethylol propionic acid and acetone, heat to 100℃ and react for 70-90min, then cool to 30-35℃, add triethylamine and react for 30-40min, add deionized water and stir for 30-40min to obtain polyurethane emulsion.

4. The method for preparing a fully surface-dried polyurethane coating according to claim 2, characterized in that: The preparation method of the modified polyurethane emulsion is as follows: take polyether polyol, single-end double-hydroxyl silicone prepolymer and 2,2-bis(hydroxymethyl)propionic acid, stir uniformly, add isophorone diisocyanate, add two drops of dibutyltin dilaurate dropwise, heat to 88-92℃ and react for 3-4h, cool to 70-72℃, add ethylene glycol solution, react for 2-2.5h, heat to 82-85℃, add branched polyglycidyl ether solution, react for 2-3h, add modified sodium alginate and 1H,1H,2H,2H-perfluorooctanol, react for 3-4h, add 2g triethylamine, stir for 3-4min, rotary evaporation to obtain modified polyurethane emulsion.

5. A process for the preparation of a fully-sintered polyurethane coating according to claim 4, characterized in that: The preparation method of the modified sodium alginate is as follows: take sodium alginate and deionized water, stir uniformly, add sodium periodate aqueous solution, react for 4-5h under light protection, add ethylene glycol, stir uniformly, dialysis, freeze-drying to obtain oxidized sodium alginate; take cinnamamide and ethanol, stir uniformly to obtain cinnamamide solution; take oxidized sodium alginate and deionized water, stir uniformly, add cinnamamide solution dropwise, react for 4-5h at 50-55℃, dialysis, freeze-drying to obtain modified sodium alginate.

6. The method for preparing a fully surface-dried polyurethane coating according to claim 1, characterized in that: The preparation method of the corrosion inhibitor loaded silica is as follows: taking emulsifier, cyclohexane and ammonia, stirring uniformly to obtain mixture A; taking benzotriazole and deionized water, stirring uniformly to obtain mixture B; under continuous stirring, mixture B is added dropwise into mixture A, stirring for 30-40 min, increasing temperature to 35-40℃, adding tetraethyl orthosilicate, reacting for 22-26 h, washing, drying to obtain the corrosion inhibitor loaded silica.

7. The method for preparing a fully surface-dried polyurethane coating according to claim 1, characterized in that: The leveling agent is any one or more of BYK 354 leveling agent and BYK 320 leveling agent.

8. The method for preparing a fully surface-dried polyurethane coating according to claim 1, characterized in that: The photoinitiator is selected from any one or more of 1-hydroxycyclohexyl phenyl ketone and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide.

9. A fully surface dry polyurethane coating prepared according to the method of any one of claims 1-8.

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