Preparation method of UV-moisture multi-cured polyurethane modified acrylate conformal coating

Abstract

The invention relates to the technical field of polyurethane, and discloses a preparation method of UV-moisture multi-cured polyurethane modified acrylate conformal coating, which comprises the following steps: mixing 100 parts by weight of polyurethane modified acrylate, 12-18 parts by weight of tertiary amine diacrylate diluent, 0.5-1 part by weight of thickener, 3.3-3.8 parts by weight of photoinitiator and the like; the UV-moisture multiple curing polyurethane modified acrylate conformal coating is obtained. Active chlorine atoms are introduced into the end position of polyurethane modified acrylate and can be subjected to quaternization reaction with tertiary amine groups of a tertiary amine diacrylate diluent, so that antibacterial quaternary ammonium salt groups are introduced, and the polyurethane paint is endowed with excellent antibacterial and bactericidal properties. Polyurethane modified acrylate has multiple crosslinking effects such as moisture curing, light curing crosslinking and hydrogen bond crosslinking at the same time, so that the polyurethane adhesive film shows higher tensile strength and elongation at break. And the paint has good water resistance and salt spray resistance.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane, and in particular to a method for preparing a UV-moisture multi-curing polyurethane modified acrylate conformal paint. Background Art

[0002] Polyurethane modified acrylate contains photocurable alkenyl groups and can be made into photocurable paints, adhesives and other products. It is widely used in PCB circuit boards, electronic and electrical, construction materials, mechanical equipment, etc. The active diluents of photocurable polyurethane modified acrylate mainly include dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, etc.

[0003] Introducing isocyanate, siloxane and other groups into the polyurethane modified acrylate molecular chain, reacting with water in the air at room temperature, increasing the crosslinking density of the molecular chain, thereby giving it good moisture curing properties. The Chinese patent with announcement number CN117925153B discloses a high-adhesion UV moisture dual-curing three-proof paint and its preparation method, using triazine nitrogen-containing heterocyclic organic compounds containing three isocyanate groups, hydroxyl-containing acrylic acid derivatives, double-terminated hydroxyl hydrogenated polybutadiene, active diluents, free radical photoinitiators, etc. as raw materials. The dual-curing three-proof paint has the advantages of strong adhesion, good salt spray resistance, high flexibility, etc., but the three-proof paint does not have good antibacterial properties, which limits its practical application in antibacterial and mildew prevention. Summary of the invention

[0004] (I) Technical problems to be solved: The present invention provides a UV-moisture multi-curing polyurethane modified acrylate three-proof paint with good mechanical properties and excellent antibacterial and mildew resistance.

[0005] (II) Technical solution: A method for preparing a UV-moisture multi-curing polyurethane modified acrylate conformal coating, comprising:

[0006] Step A: In a nitrogen atmosphere, add vacuum-dried and dehydrated polyether polyol, diisocyanate, 3-chloro-2-hydroxypropyl methacrylate, and N,N-dimethylformamide into a reaction vessel, add dibutyltin dilaurate dropwise after stirring, heat to 85-95° C., react for 1.5-3 hours, and cool to obtain polyurethane-modified acrylate.

[0007] Step B: add 100 parts by weight of polyurethane modified acrylate, 12-18 parts by weight of tertiary amine diacrylate diluent, 0.8-1.4 parts by weight of defoamer, 0.6-1 parts by weight of leveling agent, and 0.5-1 parts by weight of thickener into a container, stir and mix, add 3.3-3.8 parts by weight of photoinitiator, and obtain UV-moisture multi-curing polyurethane modified acrylate three-proof paint.

[0008] Preferably, the molar ratio of polyether polyol, diisocyanate and 3-chloro-2-hydroxypropyl methacrylate is 1:(1.3-1.36):(0.28-0.35).

[0009] Preferably, the temperature of the reaction in step A.

[0010] Preferably, the polyether polyol is polyethylene glycol, polypropylene glycol or polytetramethylene glycol.

[0011] Preferably, the diisocyanate is isophorone diisocyanate or toluene-2,4-diisocyanate.

[0012] Preferably, the photoinitiator is photoinitiator 1173 or photoinitiator 184.

[0013] Preferably, the preparation method of the tertiary amine diacrylate diluent comprises:

[0014] (1) Add a solvent, isocyanoethyl methacrylate, N-methyldiethanolamine, and triethylamine in a molar ratio of (2.8-3.6):1:(0.2-0.26) to a reaction container, react at 20-50° C. for 6-12 hours, remove the solvent by rotary evaporation, and separate by silica gel column chromatography to obtain a tertiary amine diacrylate diluent. The reaction formula is:

[0015]

[0016] Preferably, the solvent in (1) is dichloromethane or tetrahydrofuran.

[0017] (III) Technical Effect: The present invention uses 3-chloro-2-hydroxypropyl methacrylate to terminate the generated terminal isocyanate prepolymer, and by adjusting the reaction ratio of polyether polyol, diisocyanate monomer and 3-chloro-2-hydroxypropyl methacrylate, a photocurable alkenyl group and a moisture-curable isocyanate group are introduced at both ends of the polyurethane, thereby giving the polyurethane modified acrylate good photocuring and moisture-curing properties.

[0018] The present invention introduces active chlorine atoms at the end of the polyurethane modified acrylate, which can undergo quaternization reaction with the tertiary amine group of the tertiary amine diacrylate diluent during the curing process, thereby introducing antibacterial quaternary ammonium salt groups into the molecular chain of the polyurethane modified acrylate, giving the polyurethane paint excellent antibacterial and bactericidal properties.

[0019] The tertiary amine diacrylate diluent of the present invention contains carbamate groups, which can form hydrogen bond crosslinking with carbamate groups in polyurethane molecular chains, so that the polyurethane modified acrylate has multiple crosslinking effects such as moisture curing, light curing crosslinking, hydrogen bond crosslinking, etc., which improves the crosslinking degree between molecular chains, so that the polyurethane film exhibits higher tensile strength and elongation at break, and has good water and salt spray resistance. DETAILED DESCRIPTION

[0020] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] Embodiment 1:

[0022] (1) Add 500 mL of dichloromethane, 68 mmol of isocyanoethyl methacrylate, 20 mmol of N-methyldiethanolamine, and 5.2 mmol of triethylamine to a reaction container, react at 30° C. for 8 h, remove the solvent by rotary evaporation, and separate by silica gel column chromatography to obtain a tertiary amine diacrylate diluent.

[0023] (2) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polytetramethylene glycol 1000, 136 mmol of toluene-2,4-diisocyanate, 28 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.17 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 85° C., reacted for 3 h, and cooled to obtain a polyurethane-modified acrylate.

[0024] (3) Add 1000 g of polyurethane modified acrylate, 120 g of tertiary amine diacrylate diluent, 8 g of defoamer Lenco lo 2192, 10 g of leveling agent TEGO4100, and 7 g of thickener TT-935 to a container, stir and mix, and add 33 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0025] Comparative Example 1: The difference between this comparative example and Example 1 is that hydroxyethyl methacrylate is used instead of 3-chloro-2-hydroxypropyl methacrylate.

[0026] (1) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polytetramethylene glycol 1000, 136 mmol of toluene-2,4-diisocyanate, 28 mmol of hydroxyethyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.17 g of dibutyltin dilaurate was added dropwise, and the mixture was heated to 85° C., reacted for 3 h, and cooled to obtain polyurethane-modified acrylate.

[0027] (2) Add 1000 g of polyurethane modified acrylate, 120 g of tertiary amine diacrylate diluent, 8 g of defoamer Lenco lo 2192, 10 g of leveling agent TEGO4100, and 7 g of thickener TT-935 into a container, stir and mix, and add 33 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0028] Comparative Example 2: The difference between this comparative example and Example 1 is that dipropylene glycol diacrylate is used as a diluent instead of a tertiary amine diacrylate diluent.

[0029] (1) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polytetramethylene glycol 1000, 136 mmol of toluene-2,4-diisocyanate, 28 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.17 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 85° C., reacted for 3 h, and cooled to obtain a polyurethane-modified acrylate.

[0030] (2) Add 1000 g of polyurethane modified acrylate, 120 g of dipropylene glycol diacrylate diluent, 8 g of defoamer Lenco lo 2192, 10 g of leveling agent TEGO4100, and 7 g of thickener TT-935 into a container, stir and mix, and add 33 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0031] Comparative Example 3: The difference between this comparative example and Example 1 is that 2-acrylic acid-1,1'-[(methylamino)di-2,1-ethanediyl] ester (CAS No. 18507-41-0, structural formula ) to replace tertiary amine diacrylate diluent.

[0032] (1) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polytetramethylene glycol 1000, 136 mmol of toluene-2,4-diisocyanate, 28 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.17 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 85° C., reacted for 3 h, and cooled to obtain a polyurethane-modified acrylate.

[0033] (2) Add 1000 g of polyurethane modified acrylate, 120 g of 2-acrylate-1,1'-[(methylamino)di-2,1-ethanediyl] ester, 8 g of defoamer Lencol o 2192, 10 g of leveling agent TEGO4100, and 7 g of thickener TT-935 into a container, stir and mix, and add 33 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0034] Embodiment 2:

[0035] (1) Add 600 mL of tetrahydrofuran, 72 mmol of isocyanoethyl methacrylate, 20 mmol of N-methyldiethanolamine, and 5.2 mmol of triethylamine to a reaction container, react at 50° C. for 6 h, remove the solvent by rotary evaporation, and separate by silica gel column chromatography to obtain a tertiary amine diacrylate diluent.

[0036] (2) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polyethylene glycol 1000, 133 mmol of isophorone diisocyanate, 32 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.18 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 95° C., reacted for 1.5 h, and cooled to obtain a polyurethane-modified acrylate.

[0037] (3) Add 1000 g of polyurethane modified acrylate, 140 g of tertiary amine diacrylate diluent, 8 g of defoamer Lencol o 2192, 10 g of leveling agent TEGO4100, and 5 g of thickener TT-935 into a container, stir and mix, and add 33 g of photoinitiator 184 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0038] Embodiment 3:

[0039] (1) Add 500 mL of dichloromethane, 56 mmol of isocyanoethyl methacrylate, 20 mmol of N-methyldiethanolamine, and 4 mmol of triethylamine to a reaction container, react at 20° C. for 12 h, remove the solvent by rotary evaporation, and separate by silica gel column chromatography to obtain a tertiary amine diacrylate diluent.

[0040] (2) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polytetramethylene glycol 1000, 130 mmol of isophorone diisocyanate, 35 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 20 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.18 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 90° C., reacted for 2 h, and cooled to obtain a polyurethane-modified acrylate.

[0041] (3) Add 1000 g of polyurethane modified acrylate, 160 g of tertiary amine diacrylate diluent, 14 g of defoamer Lenco lo 2192, 6 g of leveling agent TEGO4100, and 8 g of thickener TT-935 to a container, stir and mix, and add 38 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0042] Embodiment 4:

[0043] (1) In a nitrogen atmosphere, 100 mmol of vacuum-dried and dehydrated polypropylene glycol 1000, 130 mmol of toluene-2,4-diisocyanate, 35 mmol of 3-chloro-2-hydroxypropyl methacrylate, and 15 mL of N,N-dimethylformamide were added to a reaction container, and after stirring, 0.17 g of dibutyltin dilaurate was added dropwise. The mixture was heated to 95° C., reacted for 1.5 h, and cooled to obtain a polyurethane-modified acrylate.

[0044] (2) Add 1000 g of polyurethane modified acrylate, 180 g of tertiary amine diacrylate diluent (prepared according to the method of Example 1), 12 g of defoamer Lencol 2192, 6 g of leveling agent TEGO4100, and 10 g of thickener TT-935 into a container, stir and mix, and add 38 g of photoinitiator 1173 to obtain a UV-moisture multi-curing polyurethane modified acrylate conformal coating.

[0045] Pour the polyurethane modified acrylate conformal paint onto the substrate and cure it for 20 seconds in a preheated UV curing machine. The main wavelength of the curing machine is 365nm and the light intensity is 800mW / cm 2 The wet curing was then carried out at 25°C for 7 days and 60% relative humidity.

[0046] The tensile properties of the cured film were tested according to GB / T 1040.1-2018 standard.

[0047] The salt spray resistance of the paint film was tested according to GB / T 1771-2007. The water washability was tested according to GB / T 1733-1993. The substrate is tinplate.

[0048] The antibacterial properties of the paint film were tested according to GB / T 21866-2008 standard. The test bacteria were Escherichia coli and Staphylococcus aureus. The antibacterial rate R = (BC) / B × 100%.

[0049] B is the average number of recovered bacteria (cfu / piece) of the blank control sample after 24 hours, and the paint film of Comparative Example 1 is used as the blank control sample.

[0050] C is the average number of recovered bacteria (cfu / piece) in the antibacterial sample after 24 hours.

[0051] Table 1 Performance test of polyurethane modified acrylate three-proof paint

[0052]

[0053] Table 2 Antibacterial rate test

[0054]

[0055]

[0056] It can be seen from Example 1 and Comparative Examples 1-3 that the polyurethane modified acrylate three-proof paint of Example 1 has higher tensile strength and elongation at break, and has very high antibacterial and antifungal properties. At the same time, it can maintain good water and salt resistance. This is mainly because the generated terminal isocyanate prepolymer is capped with 3-chloro-2-hydroxypropyl methacrylate, and photocurable olefin groups and moisture-curable isocyanate groups are introduced at both ends, respectively, giving the polyurethane modified acrylate good light curing and moisture curing properties. At the same time, active chlorine atoms are introduced at the end positions. During the curing process, quaternization reaction can occur with the tertiary amine group of the tertiary amine diacrylate diluent, thereby introducing antibacterial quaternary ammonium salt groups into the molecular chain of the polyurethane modified acrylate, giving the polyurethane paint excellent antibacterial and bactericidal properties. At the same time, the tertiary amine diacrylate diluent contains a carbamate group It can form hydrogen bond crosslinking with the carbamate groups in the polyurethane molecular chain, so that the polyurethane modified acrylate has multiple crosslinking effects such as moisture curing, light curing crosslinking, hydrogen bond crosslinking, etc., which improves the crosslinking degree between molecular chains and makes the polyurethane film show higher tensile strength and elongation at break.

[0057] In Comparative Example 1, hydroxyethyl methacrylate was used instead of 3-chloro-2-hydroxypropyl methacrylate, resulting in the end of the polyurethane-modified acrylate not containing chlorine atoms, and being unable to undergo quaternization reaction with the tertiary amine diacrylate diluent, resulting in very poor antibacterial performance of Comparative Example 1. However, the tertiary amine diacrylate diluent can undergo hydrogen bond crosslinking with the polyurethane, which is beneficial to improving the tensile properties of the polyurethane film.

[0058] Comparative Example 2 uses dipropylene glycol diacrylate as a diluent instead of the tertiary amine diacrylate diluent. It does not contain a tertiary amine group and cannot undergo a quaternization reaction with the terminal chlorine atom of the polyurethane-modified acrylate, resulting in poor antibacterial properties. It is also unable to undergo hydrogen bond crosslinking with the polyurethane and has poor tensile properties.

[0059] Comparative Example 3 uses 2-propenoic acid-1,1'-[(methylamino)di-2,1-ethanediyl] ester instead of the tertiary amine diacrylate diluent, which contains a tertiary amine group and can undergo a quaternization reaction with the terminal chlorine atom of the polyurethane-modified acrylate, and has good antibacterial properties, but cannot undergo hydrogen bond crosslinking with the polyurethane and has poor tensile properties.

[0060] From Examples 2-4, it can be seen that the polyurethane modified acrylate conformal coatings prepared by using different types of polyether polyols and diisocyanates and different amounts of tertiary amine diacrylate diluents all have excellent antibacterial rate, tensile properties, and water and salt spray resistance.

Claims

1. A method for preparing a UV-moisture multi-curing polyurethane modified acrylate conformal coating, characterized in that: The preparation method comprises the following steps: Step A, in a nitrogen atmosphere, add vacuum dried and dehydrated polyether polyol, diisocyanate, 3-chloro-2-hydroxypropyl methacrylate, and N,N-dimethylformamide into a reaction container, add dibutyltin dilaurate dropwise after stirring, heat for reaction, and then cool to obtain polyurethane modified acrylate; Step B, add 100 parts by weight of polyurethane modified acrylate having the structural formula 12-18 parts by weight of tertiary amine diacrylate diluent, 0.8-1.4 parts by weight of defoamer, 0.6-1 parts by weight of leveling agent, 0.5-1 parts by weight of thickener are stirred and mixed, and 3.3-3.8 parts by weight of photoinitiator are added to obtain UV-moisture multi-curing polyurethane modified acrylate three-proof paint.

2. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The molar ratio of the polyether polyol, diisocyanate and 3-chloro-2-hydroxypropyl methacrylate is 1:(1.3-1.36):(0.28-0.35).

3. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The reaction temperature in step A is 85-95° C. and the reaction time is 1.5-3 h.

4. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The polyether polyol is polyethylene glycol, polypropylene glycol or polytetramethylene glycol.

5. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The diisocyanate is isophorone diisocyanate or toluene-2,4-diisocyanate.

6. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The photoinitiator is photoinitiator 1173 or photoinitiator 184.

7. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 1, characterized in that: The preparation method of the tertiary amine diacrylate diluent comprises: (1) Add a solvent, isocyanoethyl methacrylate, N-methyldiethanolamine, and triethylamine into a reaction container, remove the solvent by rotary evaporation after the reaction, and separate by silica gel column chromatography to obtain a tertiary amine diacrylate diluent.

8. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 7, characterized in that: The solvent in (1) is dichloromethane or tetrahydrofuran.

9. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 7, characterized in that: The molar ratio of isocyanoethyl methacrylate, N-methyldiethanolamine and triethylamine is (2.8-3.6):1:(0.2-0.26).

10. The method for preparing the UV-moisture multi-curing polyurethane modified acrylate conformal coating according to claim 7, characterized in that: The reaction temperature in (1) is 20-50°C and the reaction time is 6-12h.

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