A UV-Michael dual-curing conformal coating and its preparation method

Abstract

The present invention relates to a UV-Michael dual-curing conformal coating. The raw materials for preparing the conformal coating include: a polyester resin, a UV monomer, a photoinitiator, a coupling agent, a leveling agent, and a catalyst. The polyester resin is prepared from a diol, a monomer having a malonic acid structure, and a dibasic acid. The conformal coating provided by the present invention can reduce the impact of unreacted UV monomers and small molecule products in the system on performance, further improving the protective performance of the coating. Furthermore, the preparation method provided by the present invention can shorten the curing time and improve production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a UV-Michael dual-curing conformal coating and a preparation method thereof. Background Art

[0002] Conformal coating is a specially formulated coating material with excellent high and low temperature resistance. After curing, it forms a transparent protective film with superior insulation, moisture resistance, leakage protection, shock resistance, dust resistance, corrosion resistance, aging resistance, and corona resistance. Conformal coating is primarily used to protect circuit boards from environmental corrosion, thereby extending the life of electrical appliances and ensuring safety and reliability.

[0003] With the continuous advancement and development of science and technology, the shortcomings of traditional conformal coatings have gradually become apparent. For commercially available UV-moisture dual-cure conformal coatings, UV curing is essential for film formation. However, UV light exposure inevitably leaves areas unreachable. While moisture curing can address areas not reached by UV curing, the isocyanate groups in the moisture-cured film react with water vapor to produce carbon dioxide, which can cause defects and degrade performance. Furthermore, moisture curing fails to remove unreacted UV monomers, resulting in small residual molecules that compromise the film's protective properties. Furthermore, conventional acrylic resins used in dual-curing conformal coatings suffer from numerous drawbacks, including poor high- and low-temperature resistance, poor aging resistance, and poor adhesion, making them difficult to meet the performance requirements of some applications. Therefore, the market urgently needs a conformal coating that cures quickly, exhibits excellent mechanical properties, is defect-free, and offers enhanced protective properties.

[0004] A flame-retardant, UV-moisture dual-cure polyurethane acrylate conformal coating (CN110684459A) addresses the problem of poor adhesion and toughness associated with UV curing alone, as well as uncured shadow areas that reduce overall protective performance. However, the reaction of isocyanate groups with water vapor produces carbon dioxide, which can lead to certain defects in the paint film.

[0005] An acrylate-modified silicone resin and its use in a UV-moisture dual-cure silicone conformal coating (CN114409905A) address the following issues: They overcome the shortcomings of traditional silicone resins, which require high temperatures and long curing times. Moisture curing also addresses the difficulty of traditional UV curing in rapidly drying the surface in dark areas. However, the silicone resin system suffers from poor mechanical strength and cannot avoid the performance impact of carbon dioxide generated by the reaction of isocyanate groups with water vapor.

[0006] A highly efficient, environmentally friendly UV-curing conformal coating (CN107573735A) addresses the following issues: it avoids the application and performance impacts of moisture-curing isocyanate groups, while also improving the drawbacks of large volume shrinkage and poor adhesion. However, its dark reaction occurs after exposure to UV light, resulting in a less pronounced effect in shadowed areas. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a UV-Michael dual-curing conformal paint without bubble generation and having excellent performance and a preparation method thereof.

[0008] In order to solve the above problems, the present invention adopts the following technical solutions:

[0009] The first object of the present invention is to provide a UV-Michael dual-curing conformal coating, wherein the raw materials for preparing the conformal coating include: polyester resin, UV monomer, photoinitiator, coupling agent, leveling agent and catalyst; wherein the polyester resin is prepared from raw material diol, monomer with malonic acid structure and dibasic acid.

[0010] Preferably, the raw materials for preparing the conformal coating do not include compounds containing isocyanate groups.

[0011] Preferably, the conformal coating is a solvent-free conformal coating.

[0012] Preferably, the diol is selected from one or more of ethylene glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 1,4-butanediol, pentanediol, neopentyl glycol, 1-5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, 1,4-cyclohexanedimethanol and diethylene glycol, preferably ethylene glycol and / or 1,4-butanediol.

[0013] Preferably, the monomer having a malonic acid structure is selected from one or more of malonic acid, monomethyl malonate, monoethyl malonate, mono-tert-butyl malonate, dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, dihexyl malonate, tert-butyl methyl malonate and tert-butyl ethyl malonate, preferably one or more of monomethyl malonate, monoethyl malonate and tert-butyl ethyl malonate, more preferably monomethyl malonate and / or monoethyl malonate.

[0014] Preferably, the dibasic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid and terephthalic acid, preferably terephthalic acid and / or succinic acid.

[0015] Preferably, the preparation of the polyester resin is carried out in the presence of a polyester catalyst.

[0016] Preferably, the polyester catalyst is selected from one or more of sodium acetate, zinc acetate, manganese acetate, antimony acetate, tetrabutyl titanate, and dibutyltin dilaurate.

[0017] Preferably, the intrinsic viscosity of the polyester resin is 0.3 to 0.5 dL / g, preferably 0.35 to 0.45 dL / g, and more preferably 0.40 to 0.45 dL / g.

[0018] Preferably, the glass transition temperature of the polyester resin is 30 to 60°C, preferably 40 to 60°C, and more preferably 45 to 55°C.

[0019] Preferably, the acid value of the polyester resin is less than 1 mgKOH / g.

[0020] Preferably, the polyester resin has a hydroxyl value of 5 to 15 mgKOH / g.

[0021] Preferably, the UV monomer is selected from one or more of tripropylene glycol diacrylate (TPGDA), dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), diethylene glycol phthalate diacrylate (PDDA), neopentyl glycol diacrylate (NPGDA), trimethylolpropane triacrylate (TMPTA), and isobornyl methacrylate (IBOMA), preferably dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane triacrylate (TMPTA), more preferably dipentaerythritol hexaacrylate (DPHA) and / or trimethylolpropane triacrylate (TMPTA).

[0022] Preferably, the photoinitiator is selected from one or more of 2-hydroxy-methylphenylpropane-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, benzoin dimethyl ether, ethyl 4-(N,N-dimethylamino)benzoate and benzophenone; preferably 2-hydroxy-methylphenylpropane-1-one.

[0023] Preferably, the coupling agent is a silane coupling agent.

[0024] Preferably, the coupling agent is one or more of silane coupling agents KH551, KH172, KH560 or KH570.

[0025] Preferably, the leveling agent is selected from one or more of BYK354, BYK355, BYK358, BYK380 and BYK390.

[0026] Preferably, the catalyst is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), tetramethylguanidine (TMG), triethylamine and hexahydropyridine, preferably one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), tetramethylguanidine (TMG), more preferably 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and / or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0027] Preferably, the polyester resin is 40-60 parts by weight, preferably 45-55 parts by weight.

[0028] Preferably, the UV monomer is 35-45 parts, preferably 40-45 parts.

[0029] Preferably, the photoinitiator is 1-4 parts, preferably 1-3 parts.

[0030] Preferably, the coupling agent is 0.5-1 part, preferably 0.5-0.8 part.

[0031] Preferably, the leveling agent is 0.5-1 part, preferably 0.5-0.8 part.

[0032] Preferably, the catalyst is 0.5-1 part, preferably 0.8-1 part.

[0033] A second object of the present invention is to provide a method for preparing any of the above-mentioned conformal coatings, the method comprising the following steps:

[0034] (1) preparing polyester resin;

[0035] (2) adding the polyester resin and UV monomer according to parts by weight into a reactor for reaction;

[0036] (3) adding a photoinitiator, a coupling agent, and a leveling agent in parts by weight in step (2) to react to obtain an intermediate product;

[0037] (4) mixing the intermediate product obtained in step (3) with a catalyst to obtain the anti-corrosion paint.

[0038] Preferably, the step of preparing the polyester resin comprises: adding a diol, a monomer having a malonic acid structure, and a dibasic acid into a reactor, heating the reaction system to perform a first reaction; and then continuing to heat the reaction system to perform a second reaction to obtain the polyester resin;

[0039] Preferably, the reaction temperature in step (2) is controlled to be 60-80°C.

[0040] Preferably, the reaction in step (2) is controlled to be carried out under stirring conditions.

[0041] Preferably, the stirring time is controlled to be 5 to 8 hours.

[0042] Preferably, the mass ratio of the intermediate product to the catalyst is controlled to be 100:(0.5-1).

[0043] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0044] The present invention introduces a malonic acid structure into the resin system, and carries out a Michael addition reaction with unreacted UV monomers in the system under appropriate catalyst conditions. In addition, the system does not contain isocyanate groups, thereby avoiding the defect of the UV-moisture curing system caused by the easy generation of carbon dioxide by the reaction of NCO groups with water vapor. This further reduces the impact of unreacted UV monomers and small molecule products in the system on the performance, and further improves the protective performance of the coating.

[0045] The preparation method of the conformal coating provided by the present invention is simple to operate, can shorten the film curing time, improve production efficiency, and is suitable for large-scale production. DETAILED DESCRIPTION

[0046] In response to the shortcomings of existing UV-moisture curing systems, which suffer from residual UV monomers and small molecules like carbon dioxide generated by the reaction, which affect the overall performance of the paint film, the inventors, through extensive and in-depth research, have ultimately developed a UV-Michael dual-curing polyester conformal coating. This coating contains no organic volatile solvents and exhibits excellent chemical resistance, high humidity and heat resistance, high cold and hot impact resistance, adhesion, and pressure resistance, thereby meeting the rapidly developing needs of the communications and electronic component fields. This invention was completed on this basis.

[0047] Unless defined otherwise, technical and scientific terms used herein have the same meanings as those in the art to which this application belongs.

[0048] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0049] Approximating terms in the specification and claims are used to modify a quantity to indicate that the invention is not limited to that specific quantity and includes acceptable modifications close to that quantity that do not result in a change in the relevant basic function. Accordingly, the use of "about," "approximately," or the like to modify a numerical value indicates that the invention is not limited to that exact numerical value. In some instances, approximating terms may correspond to the precision of the instrument used to measure the value. In the specification and claims of this application, range definitions may be combined and / or interchanged, and unless otherwise indicated, such ranges include all subranges contained therein.

[0050] The first object of the present invention is to provide a UV-Michael dual-curing conformal coating, wherein the raw materials for preparing the conformal coating include: polyester resin, UV monomer, photoinitiator, coupling agent, leveling agent and catalyst; wherein the polyester resin is prepared from raw material diol, monomer with malonic acid structure and dibasic acid.

[0051] In certain embodiments, the raw materials used to prepare the conformal coating do not include compounds containing isocyanate groups. Therefore, the conformal coating provided by the present invention avoids the drawbacks of UV-moisture curing systems due to the easy generation of carbon dioxide by the reaction of NCO groups with water vapor.

[0052] In certain embodiments, the conformal coating is a solvent-free conformal coating. The conformal coating provided by the present invention does not contain organic volatile solvents and has better mechanical properties than silicone resins.

[0053] In certain embodiments, the diol is selected from one or more of ethylene glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 1,4-butanediol, pentanediol, neopentyl glycol, 1-5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, 1,4-cyclohexanedimethanol, and diethylene glycol.

[0054] In certain embodiments, the diol is ethylene glycol and / or 1,4-butanediol.

[0055] In certain embodiments, the diol is ethylene glycol.

[0056] In certain embodiments, the monomer having a malonic acid structure is selected from one or more of malonic acid, monomethyl malonate, monoethyl malonate, mono-tert-butyl malonate, dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, dihexyl malonate, tert-butyl methyl malonate, and tert-butyl ethyl malonate.

[0057] In certain embodiments, the monomer having a malonic acid structure is one or more of monomethyl malonate, monoethyl malonate, and tert-butyl ethyl malonate.

[0058] In certain embodiments, the monomer having a malonic acid structure is monomethyl malonate and / or monoethyl malonate.

[0059] The conformal coating provided by the present invention contains a certain proportion of malonic acid structure. The active methylene group in the malonic acid structure can undergo addition reaction with the unsaturated double bond under the catalysis of a catalyst base, thereby consuming unreacted UV monomers in the shadow area of ​​ultraviolet light irradiation, further improving the reaction degree of the coating and improving resistance.

[0060] In certain embodiments, the dibasic acid is selected from one or more of succinic acid, adipic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and terephthalic acid.

[0061] In certain embodiments, the diacid is terephthalic acid and / or succinic acid.

[0062] In certain embodiments, the molar ratio of the diol, the malonic acid monomer, and the dibasic acid is 1:(0.05-0.4):(0.5-0.9).

[0063] In certain embodiments, the molar ratio of the diol, the malonic acid monomer, and the dibasic acid is 1:(0.2-0.4):(0.6-0.9).

[0064] In certain embodiments, the molar ratio of the diol, the malonic acid monomer, and the dibasic acid is 1:(0.2-0.35):(0.6-0.8).

[0065] In certain embodiments, the preparation of the polyester resin is carried out in the presence of a polyester catalyst.

[0066] In certain embodiments, the polyester catalyst is selected from one or more of sodium acetate, zinc acetate, manganese acetate, antimony acetate, tetrabutyl titanate, and dibutyltin dilaurate.

[0067] In certain embodiments, the polyester catalyst is tetrabutyl titanate.

[0068] In certain embodiments, the intrinsic viscosity of the polyester resin is 0.3 to 0.5 dL / g, such as 0.35 dL / g, 0.40 dL / g, 0.45 dL / g, etc.

[0069] In certain embodiments, the polyester resin has an intrinsic viscosity of 0.35 to 0.45 dL / g.

[0070] In certain embodiments, the polyester resin has an intrinsic viscosity of 0.40 to 0.45 dL / g.

[0071] In certain embodiments, the polyester resin has a glass transition temperature of 30 to 60°C, such as 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0072] In certain embodiments, the polyester resin has a glass transition temperature of 40 to 60°C.

[0073] In certain embodiments, the polyester resin has a glass transition temperature of 45 to 55°C.

[0074] In certain embodiments, the polyester resin has an acid value of <1 mgKOH / g.

[0075] In certain embodiments, the polyester resin has a hydroxyl value of 5 to 15 mgKOH / g.

[0076] In certain embodiments, the UV monomer is selected from one or more of tripropylene glycol diacrylate (TPGDA), dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), diethylene glycol phthalate diacrylate (PDDA), neopentyl glycol diacrylate (NPGDA), trimethylolpropane triacrylate (TMPTA), and isobornyl methacrylate (IBOMA).

[0077] In certain embodiments, the UV monomer is selected from one or more of dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), and trimethylolpropane triacrylate (TMPTA).

[0078] In certain embodiments, the UV monomer is dipentaerythritol hexaacrylate (DPHA) and / or trimethylolpropane triacrylate (TMPTA).

[0079] In certain embodiments, the photoinitiator is selected from one or more of 2-hydroxy-methylphenylpropane-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, benzoin dimethyl ether, ethyl 4-(N,N-dimethylamino)benzoate and benzophenone.

[0080] In certain embodiments, the photoinitiator is 2-hydroxy-methylphenylpropan-1-one.

[0081] In certain embodiments, the coupling agent is a silane coupling agent.

[0082] In certain embodiments, the coupling agent is one or more of the silane coupling agents KH551, KH172, KH560, or KH570.

[0083] In certain embodiments, the coupling agent is silane coupling agent KH570.

[0084] In certain embodiments, the leveling agent is selected from one or more of BYK354, BYK355, BYK358, BYK380, and BYK390.

[0085] In certain embodiments, the catalyst is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), tetramethylguanidine (TMG), triethylamine, and hexahydropyridine.

[0086] In certain embodiments, the catalyst is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and tetramethylguanidine (TMG).

[0087] In certain embodiments, the catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and / or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0088] In certain embodiments, the polyester resin is 40-60 parts by weight, for example, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, etc.

[0089] In certain embodiments, the polyester resin is present in an amount of 45-55 parts by weight.

[0090] In certain embodiments, the UV monomer is 35-45 parts, such as 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, etc.

[0091] In certain embodiments, the UV monomer is 40-45 parts.

[0092] In certain embodiments, the photoinitiator is 1-4 parts, for example, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, etc.

[0093] In certain embodiments, the photoinitiator is present in an amount of 1 to 3 parts.

[0094] In certain embodiments, the coupling agent is 0.5-1 part, such as 0.6 part, 0.7 part, 0.8 part, 0.9 part, etc.

[0095] In certain embodiments, the coupling agent is 0.5-0.8 parts.

[0096] In certain embodiments, the leveling agent is 0.5-1 part, for example, 0.6 part, 0.7 part, 0.8 part, 0.9 part, etc.

[0097] In certain embodiments, the leveling agent is 0.5-0.8 parts.

[0098] In certain embodiments, the catalyst is in an amount of 0.5-1 parts, such as 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, and the like.

[0099] In certain embodiments, the catalyst is present in an amount of 0.8-1 parts.

[0100] A second object of the present invention is to provide a method for preparing any of the above-mentioned conformal coatings, the method comprising the following steps:

[0101] (1) preparing polyester resin;

[0102] (2) adding the polyester resin and UV monomer according to parts by weight into a reactor for reaction;

[0103] (3) adding a photoinitiator, a coupling agent, and a leveling agent in parts by weight in step (2) to react to obtain an intermediate product;

[0104] (4) mixing the intermediate product obtained in step (3) with a catalyst to obtain the anti-corrosion paint.

[0105] In certain embodiments, the step of preparing the polyester resin includes: adding a diol, a monomer having a malonic acid structure, and a dibasic acid into a reactor, heating the reaction system to perform a first reaction; and then continuing to heat the reaction system to perform a second reaction to obtain the polyester resin.

[0106] In certain embodiments, the temperature of the first reaction is controlled to be 180-200°C.

[0107] In certain embodiments, the temperature of the second reaction is controlled to be 200-220°C.

[0108] In certain embodiments, the reaction temperature in step (2) is controlled to be 60-80°C, for example, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, etc.

[0109] In certain embodiments, the reaction in step (2) is controlled to be carried out under stirring conditions.

[0110] In certain embodiments, the stirring time is controlled to be 5 to 8 hours, for example, 5.5 hours, 6 hours, 6.5 hours, 7 hours, or 7.5 hours.

[0111] In certain embodiments, the mass ratio of the intermediate product to the catalyst is controlled to be 100:(0.5-1). The present invention controls the speed of the Michael addition reaction by using a suitable catalyst, shortening the film curing time while meeting the production process requirements. This allows for rapid curing, with the film being fully cured after 24 hours at 25°C or 2 hours at 60°C. The preparation process provided by the present invention can enhance reaction activity, reduce curing time, and improve production efficiency, making it suitable for large-scale production.

[0112] The third object of the present invention is to provide a use of the conformal coating as described above or the conformal coating prepared by the method as described above in the field of communications or electronic components.

[0113] To make the technical solutions and beneficial effects of the present invention more clearly understood, the following is a detailed description by way of specific examples. Unless otherwise specified, the materials, reagents, instruments, etc. used in the examples can be obtained from commercial sources or synthesized according to known methods.

[0114] Example 1

[0115] (1) Preparation of polyester resin

[0116] 0.75 mol of terephthalic acid, 0.25 mol of monoethyl malonate, 1.05 mol of ethylene glycol, and 10 g of tetrabutyl titanate were placed in a reaction kettle. The air was replaced with nitrogen, and the reaction was continued at a temperature between 180°C and 200°C with stirring until the acid value was less than 1 mg KOH / g. After the reaction, the temperature was raised to 200°C and polycondensed under vacuum with stirring until the end point. The vacuum was then relieved by the addition of nitrogen, and the product was sliced ​​and discharged to produce polyester resin 1.

[0117] (2) Preparation of conformal coating

[0118] Weigh 50 parts of the above-mentioned polyester resin 1 and 40 parts of DPHA by mass, put them into a dissolving kettle, stir and dissolve at 60-80°C for 5-8 hours, cool to 40°C after the resin is completely dissolved, then add 2 parts of 2-hydroxy-methylphenylpropane-1-one, 0.7 parts of KH570, and 0.6 parts of BYK354, filter out the kettle, and obtain solvent-free polyester conformal coating component A.

[0119] When in use, the polyester conformal paint component A is mixed with 0.8 parts of DBU to obtain the conformal paint, which is then sprayed.

[0120] Polyester resins 2 to 10 were prepared according to Table 1, which is as follows:

[0121] Table 1

[0122]

[0123]

[0124] Polyester resins 2 to 10 were prepared according to step (2) of the above embodiment 1 to obtain the corresponding conformal coatings of embodiments 2 to 10.

[0125] Polyester resin 1 was used according to the formula in Table 2 to prepare the corresponding conformal coatings of Examples 11 to 23.

[0126] Table 2

[0127]

[0128] Performance Testing

[0129] In order to verify the technical effect of the present application, the present application conducted the following performance tests on the conformal coatings prepared in Examples 1 to 23 according to national standards.

[0130] Refer to the national standard GB / T 23989-2009 for chemical resistance testing;

[0131] Conduct high and low temperature cycle tests in accordance with the national standard GB / T 2423-2001;

[0132] Conduct salt spray resistance test in accordance with national standard GB / T 1771-1991;

[0133] Refer to the national standard GB / T 2423.50 for double 85 test (1000h);

[0134] Refer to the national standard GB / T 9286-2021 for adhesion grade;

[0135] The breakdown voltage is tested with reference to the national standard GB / T 1981.2-2009.

[0136] The performance test results are shown in Table 3:

[0137] Table 3

[0138]

[0139]

[0140] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations of the claims. Various modifications and variations may be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form additional embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments merely illustrate several implementations of the present invention and do not limit the scope of protection of the patent of this invention.

Claims

1. A UV-Michael dual-curing conformal coating, characterized in that: The raw materials for preparing the conformal coating include: polyester resin, UV monomer, photoinitiator, coupling agent, leveling agent and catalyst; wherein the polyester resin is prepared from raw material diol, monomer with malonic acid structure and dibasic acid; in parts by weight, the polyester resin is 40-60 parts, the UV monomer is 35-45 parts, the photoinitiator is 1-4 parts, the coupling agent is 0.5-1 part, the leveling agent is 0.5-1 part, and the catalyst is 0.5-1 part; The diol is selected from one or more of ethylene glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 1,4-butanediol, pentanediol, neopentyl glycol, 1-5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, 1,4-cyclohexanedimethanol and diethylene glycol; The monomer having a malonic acid structure is selected from one or more of malonic acid, monomethyl malonate, monoethyl malonate, mono-tert-butyl malonate, dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, dihexyl malonate, tert-butyl methyl malonate and tert-butyl ethyl malonate; The dibasic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid and terephthalic acid; The preparation of the polyester resin is carried out in the presence of a polyester catalyst; The polyester catalyst is selected from one or more of sodium acetate, zinc acetate, manganese acetate, antimony acetate, tetrabutyl titanate, and dibutyltin dilaurate; The preparation method of the three-proof paint comprises the following steps: (1) Preparation of polyester resin; (2) adding the polyester resin and UV monomer according to parts by weight into a reactor for reaction; (3) adding a photoinitiator, a coupling agent, and a leveling agent in parts by weight in step (2) to react and obtain an intermediate product; (4) mixing the intermediate product obtained in step (3) with a catalyst to obtain the conformal coating; The steps of preparing the polyester resin include: adding a diol, a monomer having a malonic acid structure, and a dibasic acid into a reactor, heating the reaction system to perform a first reaction; and then continuing to heat the reaction system to perform a second reaction to obtain the polyester resin; The mass ratio of the intermediate product to the catalyst is controlled to be 100:(0.5~1).

2. The conformal coating according to claim 1, characterized in that: The diol is ethylene glycol and / or 1,4-butanediol.

3. The conformal coating according to claim 1, wherein: The monomer having a malonic acid structure is selected from one or more of monomethyl malonate, monoethyl malonate, and tert-butyl ethyl malonate.

4. The conformal coating according to claim 3, wherein: The monomer having a malonic acid structure is monomethyl malonate and / or monoethyl malonate.

5. The conformal coating according to claim 1, wherein: The dibasic acid is terephthalic acid and / or succinic acid.

6. The conformal coating according to claim 1, wherein: The intrinsic viscosity of the polyester resin is 0.3-0.5 dL / g.

7. The conformal coating according to claim 6, characterized in that: The intrinsic viscosity of the polyester resin is 0.35-0.45 dL / g.

8. The conformal coating according to claim 7, characterized in that: The intrinsic viscosity of the polyester resin is 0.40-0.45 dL / g.

9. The conformal coating according to claim 1, wherein: The glass transition temperature of the polyester resin is 30-60°C.

10. The conformal coating according to claim 9, characterized in that: The glass transition temperature of the polyester resin is 40-60°C.

11. The conformal coating according to claim 10, wherein: The glass transition temperature of the polyester resin is 45-55°C.

12. The conformal coating according to claim 1, wherein: The UV monomer is selected from one or more of tripropylene glycol diacrylate (TPGDA), dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA), diethylene glycol phthalate diacrylate (PDDA), neopentyl glycol diacrylate (NPGDA), trimethylolpropane triacrylate (TMPTA), and isobornyl methacrylate (IBOMA).

13. The conformal coating according to claim 12, wherein: The UV monomer is selected from one or more of dipentaerythritol hexaacrylate (DPHA), 1,6-hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA).

14. The conformal coating according to claim 13, wherein: The UV monomer is dipentaerythritol hexaacrylate (DPHA) and / or trimethylolpropane triacrylate (TMPTA).

15. The conformal coating according to claim 1, wherein: The photoinitiator is selected from one or more of 2-hydroxy-methylphenylpropane-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, benzoin dimethyl ether, ethyl 4-(N,N-dimethylamino)benzoate and benzophenone.

16. The conformal coating according to claim 15, characterized in that: The photoinitiator is 2-hydroxy-methylphenylpropane-1-one.

17. The conformal coating according to claim 1, wherein: The coupling agent is a silane coupling agent.

18. The conformal coating according to claim 17, wherein: The coupling agent is one or more of silane coupling agents KH551, KH172, KH560 or KH570.

19. The conformal coating according to claim 1, wherein: The leveling agent is selected from one or more of BYK354, BYK355, BYK358, BYK380 and BYK390.

20. The conformal coating according to claim 1, wherein: The catalyst is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), tetramethylguanidine (TMG), triethylamine and hexahydropyridine.

21. The conformal coating according to claim 20, wherein: The catalyst is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and tetramethylguanidine (TMG).

22. The conformal coating according to claim 21, wherein: The catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and / or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

23. The conformal coating according to claim 1, wherein: In terms of parts by weight, the polyester resin is 45-55 parts.

24. The conformal coating according to claim 1, wherein: In terms of parts by weight, the UV monomer is 40-45 parts.

25. The conformal coating according to claim 1, wherein: In terms of weight, the photoinitiator is 1-3 parts.

26. The conformal coating according to claim 1, wherein: In terms of weight, the coupling agent is 0.5-0.8 parts.

27. The conformal coating according to claim 1, wherein: In terms of parts by weight, the leveling agent is 0.5-0.8 parts.

28. The conformal coating according to claim 1, wherein: In terms of parts by weight, the catalyst is 0.8-1 part.

29. The conformal coating according to claim 1, wherein: The reaction temperature in step (2) is controlled to be 60-80°C.

30. The conformal coating according to claim 1, wherein: The reaction in step (2) is controlled to be carried out under stirring conditions.

31. The conformal coating according to claim 30, wherein: The stirring time is controlled to be 5 to 8 hours.

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