UV-LED (ultraviolet-light emitting diode) and moisture dual-curing conformal coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of paint, and discloses UV-LED and moisture dual-curing three-proofing paint as well as a preparation method and application thereof. The UV-LED and moisture dual-curing three-proofing paint is prepared from a polyurethane acrylate prepolymer, an acrylate modified isocyanate prepolymer, a photoinitiator and an auxiliary agent, and the polyurethane acrylate prepolymer contains a carbamate group and an acrylate double bond. According to the UV-LED and moisture dual-curing conformal coating formed by matching the specific polyurethane acrylate prepolymer and the acrylate modified isocyanate prepolymer with other components, the problem of curing oxygen inhibition of a UV-LED ultraviolet lamp can be solved; secondly, a polyurethane chain segment is introduced, the adhesive force and the impact resistance are improved, a UV and moisture dual-curing mode is adopted, the adhesive can be cured in a shadow area, a cured adhesive film has the characteristics of flexibility and toughness, the excellent protection capacity is kept in a high-low-temperature impact environment or a high-temperature and high-humidity environment, and the good popularization prospect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of paints, and in particular relates to a UV-LED and moisture dual-curing conformal paint and a preparation method and application thereof. Background Art

[0002] UV conformal coating forms a transparent protective coating after UV irradiation, which is used to protect circuit boards and other related components from environmental erosion. The conformal coating must have good high and low temperature resistance, and has excellent moisture-proof, dust-proof, corrosion-proof, pollution-proof, earthquake-resistant, and insulation properties.

[0003] Traditional conformal coatings are cured by UV mercury lamps because the wavelength of light emitted by mercury lamps is full-band UVA, UVB and UVC, including UVA: 320-400nm; UVB: 290-320nm; UVC: 100-290nm. Through the combination of photoinitiators, UVA and UVB band light can be absorbed to initiate reactions. Due to the wide wavelength and high curing efficiency, the influence of oxygen inhibition can be overcome to obtain a smooth, flat and dry conformal coating film (the dry surface does not get fingerprints or absorb dust). However, it is undeniable that mercury lamps also have many problems. In addition to ultraviolet light, mercury lamps are also accompanied by a large amount of infrared light, which brings a lot of heat, which has an adverse effect on production control. The machine needs to be preheated before work, and the production efficiency is low and the energy consumption is high. At the same time, the heavy metals contained in the lamp are not good for safety.

[0004] In recent years, with the development of UV-LED ultraviolet lamps becoming more and more mature, and breakthroughs have been made in the research and development of long-wavelength high-efficiency photoinitiators, UV-LED ultraviolet lamp curing has been greatly promoted and applied. Compared with traditional mercury lamp curing, UV-LED has the following advantages: its emission wavelength is a narrow band, mainly 365nm, 395nm and 405nm, and no large amount of heat is generated during the curing process, so it is more widely used (for example, it is suitable for the protection of heat-sensitive components); secondly, UV-LED ultraviolet lamp curing can be turned on and used immediately, without preheating, with high production efficiency and lower energy consumption; the lamp tube has a long service life and more cost advantages, etc., but there are also some differences from mercury lamps. First, the wavelength peak emitted by the UV-LED ultraviolet light source is single, and the commonly used UV-LED ultraviolet light source has a wavelength of 365nm and a narrow wavelength range. At the same time, compared with mercury lamps, the power and irradiation are low, resulting in very obvious oxygen inhibition, showing that the surface of the film is sticky after curing, so different requirements are put forward for the three-proof paint used in conjunction with it. Secondly, the new equipment of each downstream customer has mostly adopted UV-LED ultraviolet light source.

[0005] Therefore, there is an urgent need to provide a three-proof paint that can be applied to UV-LED ultraviolet lamps to solve the problem of oxygen inhibition of UV-LED ultraviolet lamp curing. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a UV-LED and moisture dual-curing conformal coating and its preparation method and application, which can solve the problem of oxygen inhibition of UV-LED ultraviolet lamp curing.

[0007] The UV-LED and moisture dual-curing conformal coating of the present invention firstly solves the problem of oxygen inhibition of UV-LED ultraviolet lamp curing by synthesizing polyurethane acrylate prepolymer and acrylic modified isocyanate prepolymer and matching with a suitable photoinitiator system; secondly, polyurethane chain segments are introduced to improve adhesion and impact resistance. In addition, the present invention adopts UV and moisture dual-curing methods, and can also cure shadow areas. After curing, the adhesive film has the characteristics of flexibility and toughness, maintains excellent protection capabilities in high and low temperature impact or high temperature and high humidity environments, and has a good promotion prospect.

[0008] A first aspect of the present invention provides a UV-LED and moisture dual-curing conformal coating.

[0009] Specifically, a UV-LED and moisture dual-curing conformal coating includes a polyurethane acrylate prepolymer, an acrylate-modified isocyanate prepolymer, a photoinitiator and an additive;

[0010] The polyurethane acrylate prepolymer contains urethane groups and acrylate double bonds.

[0011] Preferably, the auxiliary agent includes at least one of a reactive diluent, a coupling agent, a leveling agent, a defoaming agent, a water remover, and a fluorescent agent. Further preferably, the auxiliary agent includes a reactive diluent, a coupling agent, a leveling agent, a defoaming agent, a water remover, and a fluorescent agent.

[0012] Preferably, the photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenylpropanone (1173), 1-hydroxy-cyclohexyl-phenyl ketone (184), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L), methyl benzoylformate, and benzophenone. Further preferably, the photoinitiator is 1-hydroxy-cyclohexyl-phenyl ketone (184) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) or 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L). 184 is a highly efficient type I free radical non-yellowing photoinitiator. TPO or TPO-L is a highly efficient type I free radical photoinitiator with a very wide absorption wavelength range. Its effective absorption peak is 350-400nm. It takes into account both surface drying and deep curing, and is used to initiate ultraviolet polymerization reactions of unsaturated prepolymer systems. This initiator has the following three characteristics: fast curing, yellowing resistance, and low odor.

[0013] Preferably, the active diluent is selected from at least one of isobornyl acrylate, tetrahydrofuran acrylate, 4-tert-butylcyclohexyl acrylate, acryloylmorpholine, lauryl acrylate, dicyclopentenyl acrylate, 2-phenoxyethyl acrylate, ethoxylated tetrahydrofuran acrylate, propoxylated tetrahydrofuran acrylate and cyclotrimethylolpropane formal acrylate, isobornyl methacrylate, tetrahydrofuran methacrylate, tripropylene glycol diacrylate and polyethylene glycol diacrylate; further preferably, the active diluent is isobornyl acrylate, ethoxylated tetrahydrofuran acrylate and tripropylene glycol diacrylate.

[0014] Preferably, the coupling agent is a siloxane coupling agent, selected from at least one of A151 (vinyl triethoxysilane), A171 (vinyl trimethoxysilane), A172 (vinyl tri(β-methoxyethoxysilane), A174 methacryloxypropyl trimethoxysilane).

[0015] Preferably, the leveling agent is at least one of polyether siloxane-copolymer TEGO Glide 432, TEGO 466, TEGO 435, TEGO410, BYK-306, BYK-331, BYK-349, BYK-3500 or BYK-3570.

[0016] Preferably, the defoaming agent is selected from at least one of BYK-045, BYK-141, BYK-320, BYK-067A, BYK-088, TEGOFoamex N, and TEGO airex900.

[0017] Preferably, the dewatering agent is Borcher p-toluenesulfonyl isocyanate (TI) from Germany.

[0018] Preferably, the fluorescent agent is Tinopal OB from BASF of Germany.

[0019] Preferably, the UV-LED and moisture dual-curing conformal coating comprises, by weight, 8-35 parts of polyurethane acrylate prepolymer, 8-35 parts of acrylate-modified isocyanate prepolymer, 0.5-12 parts of photoinitiator and 20-70 parts of additives; further preferably, the UV-LED and moisture dual-curing conformal coating comprises, by weight, 10-30 parts of polyurethane acrylate prepolymer, 10-30 parts of acrylate-modified isocyanate prepolymer, 1-10 parts of photoinitiator and 32.061-65 parts of additives.

[0020] Preferably, the UV-LED and moisture dual-curing conformal coating comprises the following components in parts by weight:

[0021] Polyurethane acrylate prepolymer 10-30 parts

[0022] Acrylate modified isocyanate prepolymer 10-30 parts

[0023] Photoinitiator 1-10 parts

[0024] Active diluent 30-50 parts

[0025] Coupling agent 1-5 parts

[0026] 1-5 parts of leveling agent

[0027] Defoaming agent 0.01-2 parts

[0028] Dewatering agent 0.05-2 parts

[0029] Fluorescent agent 0.001-1 part.

[0030] A second aspect of the present invention provides a method for preparing a UV-LED and moisture dual-curing conformal coating.

[0031] Specifically, a method for preparing a UV-LED and moisture dual-curing conformal coating comprises the following steps:

[0032] The components are mixed to obtain the UV-LED and moisture dual-curing conformal coating.

[0033] Preferably, the raw materials for preparing the polyurethane acrylate prepolymer include difunctional polyester polyol, difunctional isocyanate monomer and hydroxyl acrylic monomer; the difunctional polyester polyol is polycarbonate polyol. Polycarbonate polyol has excellent hydrolysis resistance and yellowing resistance.

[0034] For example, bifunctional polyester polyols include Kuraray C2090, Asahi Kasei T5652 and Ube PH200.

[0035] Preferably, the difunctional isocyanate monomer is selected from at least one of isophorone diisocyanate IPDI, cyclohexane dimethylene diisocyanate HXDI or 4,4'-diisocyanate dicyclohexylmethane HMDI, which are non-yellowing difunctional isocyanates.

[0036] Preferably, the hydroxy acrylic monomer includes hydroxyethyl acrylate.

[0037] Preferably, the weight ratio of the bifunctional polyester polyol, the bifunctional isocyanate monomer and the hydroxy acrylic monomer is 60-100:(20-40):(10-40), and more preferably 80-100:(20-40):25.

[0038] Preferably, the raw materials for preparing the polyurethane acrylate prepolymer further include a reactive diluent, an antioxidant, an inhibitor and a catalyst.

[0039] Preferably, the preparation process of the polyurethane acrylate prepolymer comprises the following steps:

[0040] The bifunctional polyester polyol is dehydrated and cooled, and then an active diluent, an antioxidant and an inhibitor are added and stirred and mixed, and then a bifunctional isocyanate monomer is added, stirred, heated, reacted, and then a catalyst is added to continue the reaction. After the reaction is completed, the temperature is lowered, and a hydroxy acrylate monomer is added to continue the reaction to obtain the polyurethane acrylate prepolymer.

[0041] Further preferably, the preparation process of the polyurethane acrylate prepolymer comprises the following steps:

[0042] Add 80-100g of polycarbonate diol into a three-necked flask, dehydrate at 110-120℃ for 1-2h until the water content is less than 1000ppm, cool to below 30℃, add 20-30g of isobornyl acrylate (water content <1000ppm) and 0.1-0.5g of antioxidant and 0.01-0.05ppm of inhibitor, stir until completely dissolved, add 20-40g of IPDI, continue stirring and mixing for 5-10min, then slowly heat to 6 0-65°C, react at this temperature for 1.5h, then heat to 80-85°C, add 0.01-0.05g of dibutyltin dilaurate, continue to react for 1-1.5h until the NCO content is ≤ the designed theoretical value, then cool to 60-65°C, add 10-40g of hydroxyethyl acrylate, react at 85-88°C for 2.5-3h, until the hydroxyl peak is no longer visible in infrared and the NCO content is 0.1-0.5%, cool and discharge to obtain the polyurethane acrylate prepolymer.

[0043] The polyurethane acrylic prepolymer of the present invention has a difunctional carbon-carbon double bond and a carbamate bond. The difunctional carbon-carbon double bond can increase the photocuring rate. The introduced polyurethane chain segment can improve the adhesion, flexibility and impact resistance of the film. Secondly, it is matched with a composite photoinitiator system suitable for the 365nm absorption band, and has a high initiation efficiency in the UV-LED narrow band, solving the problem of UV-LED curing oxygen inhibition (poor surface drying). It has its own NCO structure and can be cured in moisture, that is, dark components can also be effectively protected. In addition, the present invention is also excellent in terms of electrical and moisture-heat aging resistance, and provides a feasible solution for the use of UV-LED curing for three-proof paint.

[0044] Preferably, the raw materials for preparing the acrylate-modified isocyanate prepolymer include hydroxy acrylic monomers and multifunctional isocyanate monomers.

[0045] Preferably, the raw materials for preparing the acrylate-modified isocyanate prepolymer further include an antioxidant and an inhibitor.

[0046] Preferably, the hydroxy acrylic acid monomer is hydroxyethyl acrylate.

[0047] Preferably, the multifunctional isocyanate is an HDI trimer, for example, Wanhua HT-100, Covestro N3300 or Asahi Kasei TKA etc. may be selected.

[0048] The acrylate-modified isocyanate prepolymer contains a C=C double bond and some unreacted NCO active functional groups in its structure. The NCO group can provide moisture curing, and the C=C double bond can undergo polymerization reaction with other olefinic resins and monomers to form a polymer.

[0049] Preferably, the preparation process of the acrylate-modified isocyanate prepolymer comprises the following steps:

[0050] The multifunctional isocyanate monomer, antioxidant and polymerization inhibitor are mixed, stirred and heated, and then the hydroxy acrylic acid monomer is added and reacted to obtain the acrylate-modified isocyanate prepolymer.

[0051] Further preferably, the preparation process of the acrylate-modified isocyanate prepolymer comprises the following steps:

[0052] 80-100g HDI trimer, 0.1-0.5g antioxidant and 0.01-0.05g polymerization inhibitor are added into a reaction kettle, the temperature is raised to 45-50°C, and stirred for 5-10min; then 8-15g hydroxyethyl acrylate is added, the reaction temperature is controlled at 85-88°C, the reaction is carried out for 2.5-3h, and the NCO content is tested to be about 10-16%, thereby obtaining the acrylate modified isocyanate prepolymer.

[0053] A third aspect of the present invention provides an application of a UV-LED and moisture dual-curing conformal coating.

[0054] The above-mentioned UV-LED and moisture dual-curing conformal coating is used in electronic products.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] The UV-LED and moisture dual-curing conformal coating of the present invention comprises a polyurethane acrylate prepolymer, an acrylate-modified isocyanate prepolymer, a photoinitiator and an auxiliary agent; the polyurethane acrylate prepolymer contains a carbamate group and an acrylate double bond. The UV-LED and moisture dual-curing conformal coating formed by a specific polyurethane acrylate prepolymer, an acrylate-modified isocyanate prepolymer and other components can solve the problem of oxygen inhibition of UV-LED ultraviolet lamp curing; secondly, the polyurethane segment is introduced to improve adhesion and impact resistance, and the present invention adopts a UV and moisture dual curing method, which can also cure the shadow area. After curing, the adhesive film has the characteristics of flexibility and toughness, and maintains excellent protection ability in high and low temperature impact or high temperature and high humidity environment, and has a good promotion prospect. DETAILED DESCRIPTION

[0057] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0058] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0059] The antioxidant used in the following examples or comparative examples is antioxidant 1010, and the inhibitor is p-hydroxymethylanisole MEHQ.

[0060] The active diluent is composed of isobornyl acrylate and tetrahydrofuran acrylate in a volume ratio of 1:1.

[0061] The photoinitiator was composed of 1-hydroxy-cyclohexyl-phenyl ketone (184) and ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L) in a weight ratio of 3:2.

[0062] The coupling agent is composed of A171 (vinyl trimethoxy silane) and A174 (methacryloxypropyl trimethoxy silane) in a 1:1 weight ratio.

[0063] The leveling agent is BYK-349.

[0064] The defoamer is BYK-045.

[0065] The dehydrating agent is Borcher p-toluenesulfonyl isocyanate (TI) from Germany.

[0066] The fluorescent agent is Tinopal OB from BASF of Germany.

[0067] Preparation Example 1: Preparation of polyurethane acrylate prepolymer A

[0068] 90g of polycarbonate diol T5652 was added to a three-necked flask, dehydrated at 120°C for 2h until the water content was less than 1000ppm, cooled to a temperature below 30°C, 25g of isobornyl acrylate (water content <1000ppm) and antioxidant and polymerization inhibitor were added, stirred until completely dissolved, 35g of IPDI was added, stirring and mixing continued for 10min, then the temperature was slowly raised to 65°C, reacted at this temperature for 1.5h, then the temperature was raised to 85°C, and dibutyltin dilaurate was added (the amount of antioxidant added was polycarbonate diol T565 2 and 0.5% of the total mass of isobornyl acrylate, the addition amount of inhibitor is 0.04% of the total mass of polycarbonate diol T5652 and isobornyl acrylate, and the dibutyltin dilaurate is 0.02% of the total mass of polycarbonate diol T5652 and isobornyl acrylate), and the reaction is continued for 1.5 hours until the NCO content is ≤ the designed theoretical value, and then the temperature is lowered to 60°C, 25g of hydroxyethyl acrylate is added, and the reaction is carried out at 86°C for 3 hours until the hydroxyl peak is no longer visible in infrared and the NCO content is 0.4%, the temperature is lowered and the material is discharged to obtain a polyurethane acrylate prepolymer.

[0069] Preparation Example 2: Preparation of polyurethane acrylate prepolymer B:

[0070] 90g of Polyren Chemical Polycaprolactone Polyol PCL2200A was added to a three-necked flask, dehydrated at 120°C for 2h until the water content was less than 1000ppm, cooled to a temperature below 30°C, 25g of isobornyl acrylate (water content <1000ppm) and antioxidant and polymerization inhibitor were added, stirred until completely dissolved, 35g of IPDI was added, stirring and mixing continued for 10min, then the temperature was slowly raised to 65°C, reacted at this temperature for 1.5h, then the temperature was raised to 85°C, and dibutyltin dilaurate was added (the amount of antioxidant added was 100g of polycarbonate diol). T5652 and isobornyl acrylate are 0.5% of the total mass of the polycarbonate diol T5652, the amount of the inhibitor added is 0.04% of the total mass of the polycarbonate diol T5652 and isobornyl acrylate, and the dibutyltin dilaurate is 0.02% of the total mass of the polycarbonate diol T5652 and isobornyl acrylate), and the reaction is continued for 1.5 hours until the NCO content is ≤ the designed theoretical value, and then the temperature is lowered to 60°C, 25g of hydroxyethyl acrylate is added, and the reaction is carried out at 86°C for 3 hours until the hydroxyl peak is no longer visible in the infrared and the NCO content is 0.4%, and the temperature is lowered and the material is discharged to obtain a polyurethane acrylate prepolymer.

[0071] Preparation Example 3: Preparation of polyurethane acrylate prepolymer C:

[0072] 90g of BASF polytetrahydrofuran ether glycol PolyTHF 2000 was added to a three-necked flask, dehydrated at 120°C for 2h until the water content was less than 1000ppm, cooled to a temperature below 30°C, added with 25g of isobornyl acrylate (water content <1000ppm) and antioxidant and polymerization inhibitor, stirred until completely dissolved, added with 35g of IPDI, continued to stir and mix for 10min, then slowly heated to 65°C, reacted at this temperature for 1.5h, then heated to 85°C, and added with dibutyltin dilaurate (the amount of antioxidant added was 100g of polycarbonate diol T5652 and 100g of acrylic acid). The amount of isobornyl ester added is 0.5% of the total mass of polycarbonate diol T5652, the amount of inhibitor added is 0.04% of the total mass of polycarbonate diol T5652 and isobornyl acrylate, and the amount of dibutyltin dilaurate is 0.02% of the total mass of polycarbonate diol T5652 and isobornyl acrylate), and the reaction is continued for 1.5 hours until the NCO content is ≤ the designed theoretical value, then the temperature is lowered to 60°C, 25g of hydroxyethyl acrylate is added, and the reaction is carried out at 86°C for 3 hours until the hydroxyl peak is no longer visible in the infrared and the NCO content is 0.4%, the temperature is lowered and the material is discharged to obtain a polyurethane acrylate prepolymer.

[0073] Preparation Example 4: Preparation of acrylate-modified isocyanate prepolymer

[0074] 90g HDI trimer HT-100, 0.2g antioxidant and 0.02g inhibitor were added into the reactor, heated to 50°C and stirred for 10min; then 12g hydroxyethyl acrylate was added, the reaction temperature was controlled at 88°C, the reaction was carried out for 3h, and the NCO content was tested to be about 14%, and the material was discharged to obtain acrylic modified isocyanate prepolymer.

[0075] Example 1

[0076] A UV-LED and moisture dual-curing conformal coating, comprising the following components in parts by weight:

[0077]

[0078] A method for preparing a UV-LED and moisture dual-curing conformal coating comprises the following steps:

[0079] Use a star mixer for dispersion. First, set the stirring mode A: stirring speed 1200rpm / min, stirring time 6min; set the B mode: 800rpm / min, stirring time 4min, vacuum degree 0.05MPa; put all the components into the material cup, put it into the star mixer with the set mode, select A mode to stir 3 times, and then stir once in B mode to obtain UV-LED and moisture dual-curing three-proof paint.

[0080] The difference between Example 2 and Comparative Examples 1-3 and Example 1 is that some components or dosages are different. The components and dosages of Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0081] Table 1

[0082]

[0083]

[0084] " / " in Table 1 means that the substance was not added.

[0085] Then, the performance of the three-proof coatings prepared in the above examples and comparative examples was tested, and the test method was as follows:

[0086] Viscosity: Rotational viscometer, DVII 2# / 50rpm, 25℃, test three times and calculate the average value;

[0087] Surface dry: Scrape a 200μm film on a flat PCB board, use a 365nm UV-LED lamp to cure, and the curing energy is 5000mj / cm 2 , within 30 seconds after curing, touch and observe whether there is fingerprint;

[0088] Pure moisture curing time: Scrape a 200μm film on a flat PCB board, place it in a dark environment at 25±2℃, 50±10% relative humidity, and observe and record the film formation time;

[0089] Adhesion test: Scrape a 200μm film on a flat PCB board, use 365nm UV-LED lamp to cure, and the curing energy is 5000mj / cm 2 , then placed at 25±2℃, 50±10% relative humidity for 7 days for moisture curing, and tested with 3M tape hundred grid method;

[0090] Elongation at break, body strength: Use 100mm*100mm*5mm mold to make film, use 365nm UV-LED lamp to cure, curing energy 5000mj / cm 2 Then place it at 25±2℃ and 50±10% relative humidity for 7 days of moisture curing, slice it with a dumbbell hatchet, cut 5 slices for each sample and take the average value;

[0091] Dielectric strength: Use 100mm*100mm*5mm mold to make film, use 365nm UV-LED lamp to cure, curing energy 5000mj / cm 2 , then placed at 25±2℃, 50±10% relative humidity for 7 days for moisture curing and testing;

[0092] Thermal shock (-40 to 85°C): PCB material with components, adhesive thickness 150μm±20μm, 365nm UV-LED curing method, curing energy 5000mj / cm 2 , and then placed at 25±2℃, 50±10% relative humidity for 7 days for moisture curing. After being placed in hot and cold shock for 1000h, observe whether the film is delaminated, cracked, yellowed, or bubbling.

[0093] High temperature and high humidity resistance (85°C, 85% relative humidity): PCB panel with components, spray thickness 150μm±20μm, using 365nm UV-LED lamp, curing energy 5000mj / cm 2 , Place it at 25±2℃, 50±10% relative humidity for 7 days for moisture curing, then place it in a high temperature and high humidity oven for 1000h to observe whether the film is delaminated, cracked, yellowed, or bubbling.

[0094] The test results are shown in Table 2 below, which also provides the effect data of the commercially available 7993 conformal coating.

[0095] Table 2

[0096]

[0097] From the results in Table 2 above, it can be seen that the UV-LED and moisture dual-curing conformal coating prepared by using polyurethane acrylic prepolymer A and acrylic modified isocyanate as resins, and matching with suitable reactive diluents and additives, solves the problem of oxygen inhibition of traditional UV conformal coatings during UV-LED curing, and at the same time has excellent aging properties such as resistance to cold and heat shock, high temperature and high humidity.

[0098] It can also be seen from Example 1 and Comparative Examples 1-3 that the selection of raw materials in the preparation process of polyurethane acrylic prepolymer will affect the performance of polyurethane acrylic prepolymer, and further affect the performance of the finally prepared conformal coating.

Claims

1. A UV-LED and moisture dual-curing conformal coating, characterized in that: Including polyurethane acrylate prepolymer, acrylate modified isocyanate prepolymer, photoinitiator and additives; The polyurethane acrylate prepolymer contains urethane groups and acrylate double bonds.

2. The UV-LED and moisture dual curing conformal coating according to claim 1, characterized in that: The auxiliary agent includes at least one of an active diluent, a coupling agent, a leveling agent, a defoaming agent, a dewatering agent, and a fluorescent agent.

3. The UV-LED and moisture dual curing conformal coating according to claim 1, characterized in that: The photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, methyl benzoylformate, and benzophenone.

4. The UV-LED and moisture dual curing conformal coating according to claim 1, characterized in that: The active diluent is selected from at least one of isobornyl acrylate, tetrahydrofuran acrylate, 4-tert-butylcyclohexyl acrylate, acryloylmorpholine, lauryl acrylate, dicyclopentenyl acrylate, 2-phenoxyethyl acrylate, ethoxylated tetrahydrofuran acrylate, propoxylated tetrahydrofuran acrylate and cyclotrimethylolpropane formal acrylate, isobornyl methacrylate, tetrahydrofuran methacrylate, tripropylene glycol diacrylate and polyethylene glycol diacrylate.

5. The UV-LED and moisture dual curing conformal coating according to claim 1, characterized in that: The UV-LED and moisture dual-curing conformal coating comprises, by weight, 8-35 parts of polyurethane acrylate prepolymer, 8-35 parts of acrylate-modified isocyanate prepolymer, 0.5-12 parts of photoinitiator and 20-70 parts of auxiliary agent.

6. The UV-LED and moisture dual curing conformal coating according to claim 2, characterized in that: The auxiliary agents include active diluents, coupling agents, leveling agents, defoamers, dewatering agents and fluorescent agents, and the UV-LED and moisture dual-curing conformal coating includes the following components by weight: Polyurethane acrylate prepolymer 10-30 parts Acrylate modified isocyanate prepolymer 10-30 parts Photoinitiator 1-10 parts Active diluent 30-50 parts Coupling agent 1-5 parts 1-5 parts of leveling agent Defoaming agent 0.01-2 parts Dewatering agent 0.05-2 parts Fluorescent agent 0.001-1 part.

7. The method for preparing the UV-LED and moisture dual-curing conformal coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: The components are mixed to obtain the UV-LED and moisture dual-curing conformal coating.

8. The preparation method according to claim 7, characterized in that: The raw materials for preparing the polyurethane acrylate prepolymer include bifunctional polyester polyol, bifunctional isocyanate monomer and hydroxyl acrylate monomer; the bifunctional polyester polyol is polycarbonate polyol.

9. The preparation method according to claim 8, characterized in that: The raw materials for preparing the polyurethane acrylate prepolymer also include a reactive diluent, an antioxidant, an inhibitor and a catalyst, and the preparation process of the polyurethane acrylate prepolymer includes the following steps: The bifunctional polyester polyol is dehydrated and cooled, and then an active diluent, an antioxidant and an inhibitor are added and stirred and mixed, and then a bifunctional isocyanate monomer is added, stirred, heated, reacted, and then a catalyst is added to continue the reaction. After the reaction is completed, the temperature is lowered, and a hydroxy acrylic monomer is added to continue the reaction to obtain the polyurethane acrylate prepolymer.

10. Application of the UV-LED and moisture dual-curing conformal coating according to any one of claims 1 to 6 in electronic products.

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