UV moisture dual-curing conformal coating and preparation method thereof

Abstract

The invention relates to the technical field of three-proofing paints, in particular to a UV moisture dual-curing three-proofing paint and a preparation method thereof. The conformal coating is prepared from the following raw materials in parts by weight: 10-80 parts of acrylate resin; 20 to 60 parts of a UV reactive diluent; 3-15 parts of a polyurethane latent curing agent; 1 to 10 parts of a photoinitiator; 1-5 parts of a dewatering agent; the acrylic resin comprises at least one of urethane acrylate and isocyanate modified acrylate. According to the invention, when the specific curing agent is selected, especially the oxazolidine latent curing agent or imine latent curing agent containing at least two oxazolidinyl groups is adopted, the curing time of the conformal coating in a dark environment can be greatly shortened, and meanwhile, the problems of bubbles, pinholes and the like caused by moisture in the curing process of the conformal coating can be effectively solved; good market application values are realized.

Description

Technical Field

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

[0002] Conformal coating, also known as conformal coating, is applied to the surface of printed circuit boards (PCBs) to build a protective barrier for electronic products, protecting them from harmful external environmental factors such as dust, moisture, chemicals and mold, thereby extending the service life of electronic devices and improving their stability in use.

[0003] UV-curable conformal coating is an environmentally friendly and solvent-free coating material. It uses UV light to excite chemically active liquid materials to quickly undergo cross-linking and polymerization reactions, thereby curing into a film. This process has significant advantages such as fast curing, low energy consumption, high efficiency, and low volatile organic compound (VOC) emissions. However, in actual coating operations, conformal coatings often flow under electronic components, making these areas unable to be irradiated by UV light and unable to cure. In view of this, UV conformal coatings are usually designed as UV-humidity dual-curing modes, so that the paint layers in the shadow of UV light can rely on moisture to complete the curing process. In existing technical means, UV resins containing both isocyanate (NCO) groups and acrylate groups are generally used. Among them, the acrylate group can react and cure by irradiation with UV ultraviolet light, while the isocyanate group reacts and cures by absorbing moisture in the air. However, due to the slow reaction rate between isocyanate groups and water, when UV moisture dual-curing three-proof paint is cured only by moisture, its surface drying time is relatively long, usually requiring 48-72 hours, or even longer, which limits the application efficiency of this material to a certain extent.

[0004] Chinese patent CN117757410A discloses a UV-moisture dual-curing polyurethane sealant and its preparation method, which can be cured by UV radiation or moisture, combining the advantages of UV radiation curing and moisture curing, and solving the problem of complex operation and short application period of two-component polyurethane sealant; Chinese patent CN109321125A discloses a UV-moisture dual-curing conformal paint, which increases the shelf life of the product by adding a dehydrating agent. However, these existing technologies have not solved the above technical problems, which seriously affects the scope of application. Summary of the invention

[0005] In order to solve the problems in the prior art, the first aspect of the present invention provides a UV moisture dual curing conformal coating, wherein the raw materials for preparing the conformal coating include, by weight: Acrylate resin 10-80 parts; 20~60 parts of UV active diluent; 3-15 parts of polyurethane latent curing agent; 1~10 parts of photoinitiator; 1~5 parts of dewatering agent; The acrylic resin includes at least one of polyurethane acrylate and isocyanate modified acrylate.

[0006] In one embodiment, the mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is (0-3):(1-6), which may be 0:6, 1:1, 2:3, 1:2, or 3:4.

[0007] In a preferred embodiment, the grade of the polyurethane acrylate is selected from any one of LuCure 8674, Sartomer CN996 and Sartomer CN981.

[0008] In a preferred embodiment, the brand of the isocyanate-modified acrylate is selected from any one of Sartomer CN1073, Bayer DESmolux Vp ls2396, Allnex EBECRY14141, EBECRY14250, and EBECRY14396.

[0009] In one embodiment, the polyurethane latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

[0010] In one embodiment, the oxazolidine latent curing agent contains at least two oxazolidine groups.

[0011] In one embodiment, the imine latent curing agent includes at least one of a ketimine latent curing agent and an aldimine latent curing agent.

[0012] In the present invention, when a specific curing agent is selected, especially an oxazolidine latent curing agent or an imine latent curing agent containing at least two oxazolidine groups, the curing time of the conformal coating in a lightless environment can be greatly shortened, and the problems of bubbles, pinholes, etc. caused by moisture during the curing process of the conformal coating can be effectively solved. The possible reason is that when the oxazolidine latent curing agent or the imine latent curing agent containing two or more oxazolidine groups reacts with other components in the system, the reaction activity is relatively high, and the oxazolidine latent curing agent or the imine latent curing agent having two or more oxazolidine groups reacts with other components in the system, and can react with different resin molecular chains respectively, connect multiple molecular chains together, and form a three-dimensional network structure, so that the cured paint film has a higher crosslinking density.

[0013] In one embodiment, the polyurethane latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

[0014] In one embodiment, the oxazolidine latent curing agent contains at least two oxazolidine groups.

[0015] In a preferred embodiment, the oxazolidine latent curing agent is of brand ALT402, purchased from Changde Elite New Material Technology Co., Ltd.

[0016] In a preferred embodiment, the imine latent curing agent includes at least one of a ketimine latent curing agent and an aldimine latent curing agent. More preferably, the imine latent curing agent is a ketimine latent curing agent.

[0017] In a more preferred embodiment, the ketimine latent curing agent is of brand ALT403, purchased from Changde Elite New Material Technology Co., Ltd.

[0018] In one embodiment, the UV active diluent includes at least one of monofunctional acrylate and multifunctional acrylate.

[0019] In a preferred embodiment, the monofunctional acrylate is selected from one or more combinations of isobornyl acrylate, tetrahydrofurfuryl acrylate, cyclotrimethylolpropane formal acrylate, dicyclopentadiene acrylate, (3,3,5)-trimethylcyclohexyl acrylate, and p-tert-butylcyclohexyl acrylate.

[0020] In a more preferred embodiment, the monofunctional acrylate is selected from isobornyl acrylate and / or tetrahydrofurfuryl acrylate.

[0021] In one embodiment, the multifunctional acrylate is selected from a combination of one or more of tripropylene glycol diacrylate, polyethylene glycol acrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, hydroxypivalic acid diol diacrylate, neopentyl glycol diacrylate, and trimethylolpropane triacrylate.

[0022] In one embodiment, the photoinitiator includes a combination of one or more of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, methyl o-benzoylbenzoate, benzophenone, and methyl benzoylformate.

[0023] In a preferred embodiment, the photoinitiator comprises 2-hydroxy-2-methyl-1-phenyl acetone and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide. More preferably, the mass ratio of the 2-hydroxy-2-methyl-1-phenyl acetone to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 2:1.

[0024] In one embodiment, the desiccant includes an isocyanate desiccant.

[0025] In a preferred embodiment, the isocyanate dehydrating agent is p-toluenesulfonyl isocyanate. More preferably, the p-toluenesulfonyl isocyanate is of the brand TI, purchased from Guangzhou Jianyi Chemical Import & Export Co., Ltd.

[0026] The second aspect of the present invention provides a method for preparing a UV moisture dual curing conformal coating, comprising at least the following steps: Stir acrylate resin, UV active diluent, polyurethane latent curing agent and dehydrating agent under vacuum for 1 to 2 hours, add photoinitiator and stir for 0.5 to 1 hour to obtain the product.

[0027] In one embodiment, the pressure of the vacuum state is -0.095~-0.1MPa; the stirring speed is 200~600r / min.

[0028] Beneficial Effects 1. The present invention uses a specific curing agent, especially an oxazolidine latent curing agent or an imine latent curing agent containing at least two oxazolidine groups, which can greatly shorten the curing time of the conformal coating in a lightless environment and effectively solve the problems of bubbles, pinholes, etc. caused by moisture during the curing process of the conformal coating.

[0029] 2. The present invention adopts a specific photoinitiator and a dehydrating agent, which can improve the curing rate while avoiding the yellowing problem of the system caused by moisture, thereby improving the stability of the system.

[0030] 3. The UV-moisture dual-curing conformal coating provided by the present invention relies on moisture curing in the shadowed part where UV light cannot reach, and can be cured in as fast as 12 hours, which greatly improves production efficiency compared to the prior art which requires 48 to 72 hours or even longer.

[0031] 4. The raw materials of the UV moisture dual-curing conformal coating provided by the present invention are easily available, the preparation process is simple, and it has good market application value. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The experimental methods in the examples without specifying specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0033] Example 1 In a first aspect of the present embodiment, a UV-moisture dual-curing conformal coating is provided. The raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 60 parts; 40 parts of UV active diluent; 3 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is isocyanate-modified acrylate, and the brand of the isocyanate-modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer.

[0034] The UV active diluent is isobornyl acrylate and tetrahydrofurfuryl acrylate. The mass ratio of isobornyl acrylate and tetrahydrofurfuryl acrylate is 1:1. Both isobornyl acrylate and tetrahydrofurfuryl acrylate are purchased from Changxing Chemical Industry Co., Ltd.

[0035] The polyurethane latent curing agent is an oxazolidine latent curing agent. The brand of the oxazolidine latent curing agent is ALT402, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0036] The photoinitiator is 2-hydroxy-2-methyl-1-phenyl acetone and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide. The mass ratio of the 2-hydroxy-2-methyl-1-phenyl acetone to 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 2:1.

[0037] The 2-hydroxy-2-methyl-1-phenylacetone and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide were purchased from Aigenmon International Trading (Shanghai) Co., Ltd.

[0038] The dewatering agent is p-toluenesulfonyl isocyanate. The p-toluenesulfonyl isocyanate is TI, purchased from Guangzhou Jianyi Chemical Import & Export Co., Ltd.

[0039] A second aspect of the present embodiment provides a method for preparing a UV moisture dual curing conformal coating, comprising the following steps: Stir acrylate resin, UV active diluent, polyurethane latent curing agent and dewatering agent under vacuum for 1 hour, add photoinitiator and stir for 0.5 hour to obtain the product.

[0040] The pressure of the vacuum state is -0.095 MPa; the stirring speed is 500 r / min.

[0041] Example 2 The specific implementation of this embodiment is the same as that of embodiment 1, except that the polyurethane latent curing agent in this embodiment is a ketimine latent curing agent. The brand of the ketimine latent curing agent is ALT403, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0042] Example 3 The specific implementation of this embodiment is the same as that of Example 1, except that the UV-active diluent described in this embodiment is isobornyl acrylate, which is purchased from Changxing Chemical Industry Co., Ltd.

[0043] The polyurethane latent curing agent is a ketimine latent curing agent. The brand of the ketimine latent curing agent is ALT403, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0044] Example 4 The specific implementation of this embodiment is the same as that of Example 1, except that the first aspect of this embodiment provides a UV moisture dual curing conformal coating, and the raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 3 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0045] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0046] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0047] Example 5 The specific implementation of this embodiment is the same as that of Example 1, except that the first aspect of this embodiment provides a UV moisture dual curing conformal coating, and the raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 5 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0048] The mass ratio of the polyurethane acrylate to the isocyanate modified acrylate is 2:3.

[0049] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0050] Example 6 The specific implementation of this embodiment is the same as that of Example 1, except that the first aspect of this embodiment provides a UV moisture dual curing conformal coating, and the raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 3 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0051] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0052] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0053] The polyurethane latent curing agent is a ketimine latent curing agent. The brand of the ketimine latent curing agent is ALT403, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0054] Example 7 The specific implementation of this embodiment is the same as that of Example 1, except that the first aspect of this embodiment provides a UV moisture dual curing conformal coating, and the raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 5 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0055] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0056] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0057] The polyurethane latent curing agent is a ketimine latent curing agent. The brand of the ketimine latent curing agent is ALT403, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0058] Example 8 The specific implementation of this embodiment is the same as that of Example 1, except that the first aspect of this embodiment provides a UV moisture dual curing conformal coating, and the raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 5 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent; The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0059] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0060] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0061] The polyurethane latent curing agent is a ketimine latent curing agent. The brand of the ketimine latent curing agent is ALT403, which is purchased from Changde Elite New Material Technology Co., Ltd.

[0062] The UV active diluent is tetrahydrofurfuryl acrylate, which is purchased from Changxing Chemical Industry Co., Ltd.

[0063] Comparative Example 1 The specific implementation of this comparative example is the same as that of Example 1, except that, in the first aspect of this comparative example, a UV moisture dual-curing conformal coating is provided. The raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 60 parts; 40 parts of UV active diluent; 3 parts of photoinitiator; 1 part of dewatering agent.

[0064] Comparative Example 2 The specific implementation of this comparative example is the same as that of Example 1, except that, in the first aspect of this comparative example, a UV moisture dual-curing conformal coating is provided. The raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 3 parts of photoinitiator; 1 part of dewatering agent.

[0065] The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0066] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0067] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0068] Comparative Example 3 The specific implementation of this comparative example is the same as that of Example 1, except that, in the first aspect of this comparative example, a UV moisture dual-curing conformal coating is provided. The raw materials for preparing the conformal coating include, in parts by weight: Acrylate resin 50 parts; 50 parts of UV active diluent; 2 parts of polyurethane latent curing agent; 3 parts of photoinitiator; 1 part of dewatering agent.

[0069] The acrylic resin is polyurethane acrylate and isocyanate modified acrylate.

[0070] The mass ratio of the polyurethane acrylate to the isocyanate-modified acrylate is 2:3.

[0071] The isocyanate modified acrylate is Bayer DESmolux Vp ls2396, purchased from Bayer. The polyurethane acrylate is LuCure 8674, purchased from Guangzhou Runao Chemical Materials Co., Ltd.

[0072] The polyurethane latent curing agent contains an oxazolidinyl group, has a brand name of ALT201, and is purchased from Changde Elite New Material Technology Co., Ltd.

[0073] Performance Testing The UV moisture dual-curing conformal paint prepared in each embodiment and comparative example was brushed with 150 μm, placed in a lightless environment for curing, and the surface drying time was tested according to method B of GB / T1728-2020. The test results are shown in Table 1.

[0074] It can be seen from Table 1 that the curing time of the UV moisture dual curing conformal coatings prepared in Examples 1-8 in a lightless environment is significantly lower than that of the comparative example samples; among them, the UV moisture dual curing conformal coating prepared in this example can be cured in as fast as 12 hours, which is 48 to 72 hours required in the prior art, greatly improving the production efficiency.

[0075] Table 1

Claims

1. A UV moisture dual curing conformal coating, characterized in that: In parts by weight, the raw materials for preparing the three-proof paint include: Acrylate resin 10-80 parts; 20~60 parts of UV active diluent; 3-15 parts of polyurethane latent curing agent; 1~10 parts of photoinitiator; 1~5 parts of dewatering agent; The acrylic resin includes at least one of polyurethane acrylate and isocyanate modified acrylate.

2. The UV moisture dual curing conformal coating according to claim 1, characterized in that: The polyurethane latent curing agent includes at least one of an imine latent curing agent and an oxazolidine latent curing agent.

3. The UV moisture dual curing conformal coating according to claim 2, characterized in that: The oxazolidine latent curing agent contains at least two oxazolidine groups.

4. The UV moisture dual curing conformal coating according to claim 2, characterized in that: The imine latent curing agent includes at least one of a ketimine latent curing agent and an aldimine latent curing agent.

5. The UV moisture dual curing conformal coating according to claim 1, characterized in that: The mass ratio of the polyurethane acrylate to the isocyanate modified acrylate is (0-3):(1-6).

6. The UV moisture dual curing conformal coating according to claim 1, characterized in that: The UV active diluent includes at least one of monofunctional acrylate and multifunctional acrylate.

7. The UV moisture dual curing conformal coating according to claim 1, characterized in that: The photoinitiator includes one or more combinations of 2-hydroxy-2-methyl-1-phenylacetone, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, methyl o-benzoylbenzoate, benzophenone, and methyl benzoylformate.

8. The UV moisture dual curing conformal coating according to claim 7, characterized in that: The photoinitiator includes 2-hydroxy-2-methyl-1-phenylpropanone and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

9. The UV moisture dual curing conformal coating according to claim 1, characterized in that: The dehydrating agent includes an isocyanate dehydrating agent.

10. A method for preparing a UV moisture dual curing conformal coating according to any one of claims 1 to 9, characterized in that: At least the following steps are included: Stir acrylate resin, UV active diluent, polyurethane latent curing agent and dehydrating agent under vacuum for 1 to 2 hours, add photoinitiator and stir for 0.5 to 1 hour to obtain the product.

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