A uv moisture dual-curing three-proofing paint

Abstract

The application discloses a UV and moisture dual-curing three-protection paint and belongs to the technical field of three-protection paint. The UV and moisture dual-curing three-protection paint comprises the following components in percentage by mass: 5-50% of aliphatic difunctional polyurethane acrylic resin, 10-60% of dual-curing polyurethane acrylate resin, 15-50% of acrylate monomer, 1.05-10% of photoinitiator, 0-2% of water-removing agent, 0-2% of antioxidant, 0.01-2% of polymerization inhibitor, 0.05-2% of defoaming agent and 0.1-2% of fluorescent powder; wherein the aliphatic difunctional polyurethane acrylic resin is Lanxess L-6201. The three-protection paint can improve the adhesion of the cured layer under the premise of realizing sufficient curing with low energy consumption, thereby enhancing the uniformity and neatness when the board is broken, and effectively avoiding the problem that filamentary substances are easily generated at the fracture during the board breaking.

Description

Technical Field

[0001] This invention relates to the field of conformal coating technology, specifically to a UV-curable moisture-curing conformal coating. Background Technology

[0002] Conformal coating is a specially formulated coating with excellent high and low temperature resistance, as well as superior insulation, moisture resistance, salt spray resistance, mildew resistance, leakage prevention, shock resistance, dust resistance, corrosion resistance, aging resistance, and corona resistance. Polyurethane conformal coatings, in particular, offer superior protection due to their fast drying, strong adhesion, good impact resistance, excellent electrical insulation, excellent flexibility, abrasion resistance, and chemical resistance, making them more suitable for corrosion protection of circuit boards. Currently, UV / moisture dual-curing polyurethane conformal coatings used for the protection of electronic products primarily utilize polyurethane acrylate resins and other resin monomers and additives, and are typically cured using traditional initiators such as TPO or TMO. In actual production, after the existing polyurethane conformal coating is sprayed onto circuit boards or other substrates and cured in a UV curing oven, operators need to separate large circuit boards containing multiple small circuit boards or remove edge strips. However, due to the low activation efficiency of traditional initiators leading to insufficient curing or poor adhesion between the conformal coating and the substrate, the cured layer is prone to not completely breaking and separating at the break point during the separation process, forming filaments. This not only greatly affects the product appearance but also increases the difficulty of subsequent processes and the workload of operators, reducing production efficiency. In addition, existing polyurethane conformal coatings struggle to balance low energy consumption with excellent curing performance, affecting process stability and operational efficiency.

[0003] In view of this, it is essential to develop a UV moisture dual-curing conformal coating that can achieve full curing with low energy consumption and improve the adhesion between the cured layer and the substrate, thereby ensuring neat breakage during board separation and avoiding the formation of filaments. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a UV moisture dual-curing conformal coating. This conformal coating can improve the adhesion of the cured layer while ensuring full curing with low energy consumption, thereby enhancing the uniformity and neatness of the board during separation and effectively avoiding the problem of filaments being generated at the break point during board separation.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A UV moisture-curing conformal coating comprises the following components by mass percentage: 5-50% aliphatic difunctional polyurethane acrylate resin, 10-60% dual-curing polyurethane acrylate resin, 15-50% acrylate monomer, 1.05-10% photoinitiator, 0-2% dehydrating agent, 0-2% antioxidant, 0.01-2% polymerization inhibitor, 0.05-2% defoamer, and 0.1-2% fluorescent powder; wherein the aliphatic difunctional polyurethane acrylate resin is Lankel L-6201.

[0007] In a preferred embodiment of the present invention, the amount of the aliphatic difunctional polyurethane acrylic resin is 10-30%. The aliphatic difunctional polyurethane acrylic resin has no moisture curing function and only contains unsaturated double bonds that can be cured by UV.

[0008] In a preferred embodiment of the present invention, the acrylate monomer is at least one selected from isobornyl acrylate, isobornyl methacrylate, isooctyl acrylate, isooctyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, ethoxytrimethylolpropane triacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, n-butyl acrylate, isodecanyl acrylate, laurate acrylate, cyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-tert-butylcyclohexyl acrylate, dicyclopentenyl acrylate, pentaerythritol tetraacrylate, 4-acryloylmorpholine, ethoxyethoxyethyl acrylate, β-hydroxyethyl methacrylate, isobornyl acrylate, β-carboxyethyl acrylate, tripropylene glycol diacrylate, and pentaerythritol triacrylate.

[0009] In a preferred embodiment of the present invention, the photoinitiator is composed of 2-hydroxy-2-methylphenylacetone, 2,4,6-trimethylbenzoyl-bis(p-tolyl)phosphine oxide and benzophenone.

[0010] In a preferred embodiment of the present invention, the amounts of each component in the photoinitiator are as follows: 0.5-4% 2-hydroxy-2-methylphenylpropanone, 0.5-4% 2,4,6-trimethylbenzoyl-bis(p-tolyl)phosphine oxide, and 0.05-2% benzophenone.

[0011] In a preferred embodiment of the present invention, the dual-curing polyurethane acrylate resin has a light-curing group and a moisture-curing group, wherein the light-curing group is one or more of vinyl, acryloyloxy, and mercapto groups; and the moisture-curing group is isocyanate or silaneoxy. More preferably, the dual-curing polyurethane acrylate resin is at least one of EBECRYL® 4141, EBECRYL® 4396, and EBECRYL® 4150.

[0012] In a preferred embodiment of the present invention, the dehydrating agent is one or more of the following: p-methylbenzenesulfonyl isocyanate dehydrating agents, oxazolidine dehydrating agents, and triethyl orthoformate dehydrating agents; the antioxidant is at least one of 2,6-di-tert-butyl-4-methylphenol, tea polyphenols, butylated hydroxyanisole, and tert-butylhydroquinone; and the polymerization inhibitor is a p-hydroxyanisole polymerization inhibitor.

[0013] In a preferred embodiment of the present invention, the defoamer is at least one selected from mineral oil defoamers, alcohol defoamers, fatty acid and fatty acid ester defoamers, amide defoamers, phosphate ester defoamers, organosilicon defoamers, polyether defoamers, and polyether-modified polysiloxane defoamers. More preferably, the defoamer is BYK-361.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The UV moisture dual-curing conformal coating of this invention improves the physical properties of the cured layer, such as adhesion, by using a low-energy, fast-curing aliphatic difunctional polyurethane polyacrylate resin. This ensures rapid and complete curing of the conformal coating under low UV energy, effectively enhancing the uniformity and neatness of the fracture surface during curing. It avoids the problem of filamentous material at the fracture surface during panel separation, reduces the difficulty of subsequent processes, and decreases the labor intensity of operators, significantly improving operational efficiency and product quality. This results in stable overall product performance and meets the industrial application requirements for energy conservation, emission reduction, and high-efficiency production. Attached Figure Description

[0016] Figure 1 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Example 1 of the present invention on a separate board.

[0017] Figure 2 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Example 2 of the present invention on a separate board.

[0018] Figure 3 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Example 3 of the present invention on a separate board.

[0019] Figure 4 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Example 4 of the present invention.

[0020] Figure 5 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Example 5 of the present invention on a separate board.

[0021] Figure 6 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Comparative Example 1 of the present invention on a separate board.

[0022] Figure 7 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Comparative Example 2 of the present invention on a separate board.

[0023] Figure 8 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Comparative Example 3 of the present invention on a separate board.

[0024] Figure 9 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Comparative Example 4 of the present invention on a separate board.

[0025] Figure 10 This is a diagram showing the effect of the UV moisture dual-curing conformal coating prepared in Comparative Example 5 of the present invention on a separate board. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] The UV-curable moisture-curing conformal coating provided by this invention addresses the problem of existing conformal coatings exhibiting filamentous material at the break points during panel separation, which increases the difficulty of subsequent processing. This UV-curable moisture-curing conformal coating comprises the following components by mass percentage: 5-50% aliphatic difunctional polyurethane acrylate resin, 10-60% dual-curing polyurethane acrylate resin, 15-50% acrylate monomer, 1.05-10% photoinitiator, 0-2% dehydrating agent, 0-2% antioxidant, 0.01-2% polymerization inhibitor, 0-2% defoamer, and 0-2% fluorescent powder. During research and development, the applicant discovered that using the aliphatic difunctional polyurethane acrylate resin Lankel L-6201 as a key film-forming substance in the conformal coating, supplemented with dual-curing polyurethane acrylate resin, not only maintains good adhesion between the cured layer and the substrate, ensuring clean breaks during panel separation and preventing filamentous material formation, but also enables the cured layer to achieve rapid and thorough curing under low UV energy. Furthermore, the amount of aliphatic difunctional polyurethane acrylic resin used is preferably 10-30%.

[0028] In the above formulation, the photoinitiator consists of 2-hydroxy-2-methylphenylacetone (photoinitiator 1173), 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide (TMO), and benzophenone (photoinitiator BP). This photoinitiator combination ensures efficient excitation at low UV energy, achieving rapid and complete curing of the cured layer and reducing energy consumption. Specifically, the amounts of each component in the photoinitiator are as follows: 0.5-4% 2-hydroxy-2-methylphenylacetone, 0.5-4% 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide, and 0.05-2% benzophenone.

[0029] Preferably, the acrylate monomer is at least one selected from isobornyl acrylate, isobornyl methacrylate, isooctyl acrylate, isooctyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, ethoxytrimethylolpropane triacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, n-butyl acrylate (BA), isodecanyl acrylate, laurate acrylate, cyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-tert-butylcyclohexyl acrylate, dicyclopentenyl acrylate, pentaerythritol tetraacrylate, 4-acryloylmorpholine (ACMO), ethoxyethoxyethyl acrylate (EOEOEA), β-hydroxyethyl methacrylate, isobornyl acrylate, β-carboxyethyl acrylate, tripropylene glycol diacrylate, and pentaerythritol triacrylate. The dual-curing polyurethane acrylate resin is EBECRYL® 4141, EBECRYL® 4396, or EBECRYL® 4150. The dehydrating agent is p-toluenesulfonyl isocyanate (PTSI). The antioxidant is 2,6-di-tert-butyl-4-methylphenol (BHT). The polymerization inhibitor is p-hydroxyanisole (MeHQ). The defoamer is surface additive BYK-361. The fluorescent powder is Tinopal OB manufactured by BASF.

[0030] Example 1

[0031] A UV moisture-curing conformal coating comprises the following components by mass percentage: 125% Lankel L-620, 18.5% EBECRYL®4141, 13% butyl acrylate, 5% 4-acryloylmorpholine, 29.09% EOEOEA, 3.5% photoinitiator 1173, 2.5% TMO, 1.1% photoinitiator BP, 0.2% PTSI, 0.2% BHT, 0.11% MeHQ, 1% BYK-361, and 0.8% Tinopal OB.

[0032] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0033] Example 2

[0034] A UV moisture-curing conformal coating comprises the following components by mass percentage: 28% Lankel L-620, 15.5% EBECRYL®4141, 13% butyl acrylate, 5% 4-acryloylmorpholine, 29.09% EOEOEA, 3.5% photoinitiator 1173, 2.5% TMO, 1.1% photoinitiator BP, 0.2% PTSI, 0.2% BHT, 0.11% MeHQ, 1% BYK-361, and 0.8% Tinopal OB.

[0035] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0036] Example 3

[0037] A UV moisture-curing conformal coating comprises the following components by mass percentage: 15% Lankel L-6201, 28.5% EBECRYL®4141, 13% butyl acrylate, 5% 4-acryloylmorpholine, 29.09% EOEOEA, 3.5% photoinitiator 1173, 2.5% TMO, 1.1% photoinitiator BP, 0.2% PTSI, 0.2% BHT, 0.11% MeHQ, 1% BYK-361, and 0.8% phosphor Tinopal OB.

[0038] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0039] Example 4

[0040] A UV moisture-curing conformal coating comprises the following components by mass percentage: 13% Lankel L-6201, 35% EBECRYL®4396, 44.09% isobornyl acrylate, 3% photoinitiator 1173, 3% TMO, 1.3% photoinitiator BP, 0.11% MeHQ, and 0.5% BYK-361.

[0041] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0042] Example 5

[0043] A UV moisture-curing conformal coating comprises the following components by mass percentage: 120% Lankel L-620, 13% EECRYL® 4150, 15% EECRYL® 4396, 43.80% ethoxyethyl acrylate, 4% photoinitiator 1173, 2.5% TMO, 1% photoinitiator BP, 0.2% MeHQ, and 0.5% BYK-361.

[0044] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0045] Comparative Example 1

[0046] A UV moisture-curing conformal coating comprises the following components by mass percentage: 43.5% Lankel L-620, 13% butyl acrylate, 5% 4-acryloylmorpholine, 29.09% EOEOEA, 3.5% photoinitiator 1173, 2.5% TMO, 1.1% photoinitiator BP, 0.2% PTSI, 0.2% BHT, 0.11% MeHQ, 1% BYK-361, and 0.8% Tinopal OB.

[0047] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0048] Comparative Example 2

[0049] A UV moisture-curing conformal coating comprises the following components by mass percentage: Kunshan Castel CURE9581 25%, EBECRYL®4141 18.5%, butyl acrylate 13%, 4-acryloylmorpholine 5%, EOEOEA 29.09%, photoinitiator 1173 3.5%, TMO 2.5%, photoinitiator BP 1.1%, PTSI 0.2%, BHT 0.2%, MeHQ 0.11%, BYK-361 1%, and Tinopal OB 0.8%.

[0050] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0051] Comparative Example 3

[0052] A UV moisture-curing conformal coating comprising the following components by mass percentage: EBECRYL® 4396 48%, isoborneol acrylate 44.05%, TMO 7.3%, MeHQ 0.11%, and BYK-361 0.5%.

[0053] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0054] Comparative Example 4

[0055] A UV moisture-curing conformal coating comprises the following components by mass percentage: 12% Lankel L-620, 21% EBECRYL®4150, 25% EBECRYL®4396, 43.80% ethoxyethyl acrylate, 4% photoinitiator 1173, 2.5% TMO, 1% photoinitiator BP, 0.2% MeHQ, and 0.5% BYK-361.

[0056] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0057] Comparative Example 5

[0058] A UV moisture-curing conformal coating comprises the following components by mass percentage: 12% Lankel L-620, 21% EECRYL® 4150, 25% EECRYL® 4396, 43.80% ethoxyethyl acrylate, 7.5% photoinitiator 1173, 0.2% MeHQ, 0.3% BYK-361, and 0.2% Tinopal OB.

[0059] Mix the components in the above proportions and stir thoroughly until homogeneous to obtain a UV moisture-curing conformal coating.

[0060] Board separation effect comparison test

[0061] The conformal coatings prepared in Examples 1-5 and Comparative Examples 1-5 were applied to circuit boards under the same conditions and cured according to the same process. After curing, the surface dryness and adhesion performance were observed and the same operator was asked to perform the board separation operation to observe the separation effect.

[0062] 1. Testing Method

[0063] UV curing oven: SK-103-300GDP, Shenzhen Sankun Technology Co., Ltd.; UV curing energy: UVA 400-420mJ / cm² 2 UVB 500-520mJ / cm 2 .

[0064] Surface Drying: Apply a uniform layer of conformal coating to the FR4 board using a 100µm thick applicator. After passing through a UV curing oven, let it stand at room temperature for 1 minute. Touch the surface with your finger and lift it off. Rate the surface stickiness from 0 to 5, where 0 is not sticky at all, 1 is slightly sticky, 2 is somewhat sticky, 3 is quite sticky (the FR4 board will slightly lift off the table with your finger and then fall off immediately), 4 is very sticky (the FR4 board will lift off the table quite a distance with your finger before falling off), and 5 is extremely sticky (the FR4 board will lift off the table with your finger and not fall off).

[0065] Adhesion: Apply a uniform layer of conformal coating to the FR4 board using a 100µm thick applicator. After passing through a UV curing oven, allow it to stand at room temperature for 1 minute, and then test using the cross-cut adhesion test. Adhesion is graded from 0 to 5, with grade 0 indicating the best adhesion and grade 5 indicating the worst adhesion.

[0066] Separation: Apply a layer of conformal coating evenly to the edge of the PCBA board with a brush. After passing through a UV curing oven, let it stand at room temperature for 1 minute. Place the board edge into the groove of the separator and pry the board body apart by hand. Observe whether the cross-section is clean and whether there are any filamentous objects.

[0067] The results are shown in Table 1 and... Figures 1-10 .

[0068] Table 1. Separation effect of circuit boards prepared using the conformal coatings of Examples 1-5 and Comparative Examples 1-5

[0069]

[0070] Depend on Figures 1-10 As shown in Table 1, when the formulation ratio of the present invention is used, test results with good curing and clean, stringless cross-sections can be obtained. When aliphatic difunctional polyurethane acrylic resin is not used, stringing or peeling of the cross-section occurs. When aliphatic difunctional polyurethane acrylic resin is used but not the aliphatic difunctional polyurethane acrylic resin specified in the present invention, stringing or peeling of the cross-section occurs. When the aliphatic difunctional polyurethane acrylic resin specified in the present invention is used but the amount is too small, stringing or peeling of the cross-section occurs. When the initiator combination of the present invention is not used, poor surface drying and poor curing occur. When only a portion of the initiator of the present invention is used instead of the entire initiator combination, poor surface drying and poor curing also occur.

[0071] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A UV moisture-curing conformal coating, characterized in that: It includes the following components by mass percentage: 5-50% aliphatic difunctional polyurethane acrylic resin, 10-60% dual-curing polyurethane acrylate resin, 15-50% acrylate monomer, 1.05-10% photoinitiator, 0-2% dehydrating agent, 0-2% antioxidant, 0.01-2% polymerization inhibitor, 0-2% defoamer, and 0-2% fluorescent powder; The aliphatic difunctional polyurethane acrylic resin is Lankel L-6201; the photoinitiator is composed of 2-hydroxy-2-methylphenylpropanone, 2,4,6-trimethylbenzoyl-bis(p-tolyl)phosphine oxide and benzophenone.

2. The UV moisture dual-curing conformal coating according to claim 1, characterized in that: The amount of the aliphatic difunctional polyurethane acrylic resin used is 10-30%.

3. The UV moisture dual-curing conformal coating according to claim 1 or 2, characterized in that: The acrylate monomer is at least one of the following: isobornyl acrylate, isobornyl methacrylate, isooctyl acrylate, isooctyl methacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, ethoxytrimethylolpropane triacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, n-butyl acrylate, isodecanyl acrylate, laurate acrylate, cyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-tert-butylcyclohexyl acrylate, dicyclopentenyl acrylate, pentaerythritol tetraacrylate, 4-acryloylmorpholine, ethoxyethoxyethyl acrylate, β-hydroxyethyl methacrylate, isobornyl acrylate, β-carboxyethyl acrylate, tripropylene glycol diacrylate, and pentaerythritol triacrylate.

4. The UV moisture dual-curing conformal coating according to claim 1, characterized in that: The amounts of each component in the photoinitiator are as follows: 0.5-4% 2-hydroxy-2-methylphenylpropanone, 0.5-4% 2,4,6-trimethylbenzoyl-bis(p-tolyl)phosphine oxide, and 0.05-2% benzophenone.

5. The UV moisture dual-curing conformal coating according to claim 1 or 2, characterized in that: The dual-curing polyurethane acrylate resin has a light-curing group and a moisture-curing group. The light-curing group is one or more of vinyl, acryloyloxy, and mercapto groups. The moisture-curing group is isocyanate or silaneoxy.

6. The UV moisture dual-curing conformal coating according to claim 1 or 2, characterized in that: The dehydrating agent is one or more of the following: p-methylbenzenesulfonyl isocyanate dehydrating agents, oxazolidine dehydrating agents, and triethyl orthoformate dehydrating agents; the antioxidant is at least one of 2,6-di-tert-butyl-4-methylphenol, tea polyphenols, butylated hydroxyanisole, and tert-butylhydroquinone; and the polymerization inhibitor is a p-hydroxyanisole polymerization inhibitor.

7. The UV moisture dual-curing conformal coating according to claim 1 or 2, characterized in that: The defoamer is at least one of the following: mineral oil defoamer, alcohol defoamer, fatty acid and fatty acid ester defoamer, amide defoamer, phosphate ester defoamer, organosilicon defoamer, polyether defoamer, and polyether-modified polysiloxane defoamer.

Images