A dual-curing coating, its preparation method and application

Abstract

This invention discloses a dual-curing coating, its preparation method, and its application, relating to the field of coating technology. The dual-curing coating of this invention comprises the following components: by mass parts, it includes 34-50 parts of dual-curing polyurethane acrylate resin, 3-7 parts of epoxy-containing trimethoxysilane, 35-50 parts of reactive diluent, 3-8 parts of photoinitiator, 2-5 parts of dehydrating agent, 0.2-0.5 parts of polymerization inhibitor, 0.5-2 parts of rheology modifier, and 0.5-1 part of surfactant; wherein the dual-curing polyurethane acrylate resin contains isocyanate groups and olefin bonds. The hybrid UV-moisture dual-curing coating obtained by this invention has the characteristics of strong adhesion, excellent electrical properties, strong corrosion resistance, non-sagging when applied thickly, good storage stability, and easy spraying. It can be applied to coating in the plastics, wood, metal coil, electronics, and circuit board industries, especially in the circuit board industry.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a dual-curing coating, its preparation method, and its application. Background Technology

[0002] Ultraviolet (UV) curing coatings are characterized by fast curing speed, high efficiency, and environmental friendliness and energy saving. They are widely used in coating, bonding, and encapsulation of plastics, wood, metal coils, electronic appliances, circuit boards, and other fields. UV-curing coatings undergo a polymerization reaction under UV light irradiation, leading to cross-linking and film formation. However, the necessity of UV irradiation for this reaction limits their application to two-dimensional planar workpieces. For complex three-dimensional workpieces, the presence of non-illuminated (dark) areas prevents complete curing or prevents the coating from curing at all. To address this issue, current research focuses on three main areas: 1. Developing multi-angle UV three-dimensional irradiation curing equipment; 2. Developing novel photoinitiators to facilitate the cross-linking reaction from the illuminated area to the dark area; 3. Developing UV-dark dual-curing technology, enabling the coating to complete curing and cross-linking through two independent, non-interfering reactions.

[0003] However, the following problems still exist: 1. When using multi-angle ultraviolet three-dimensional irradiation equipment to irradiate and cure workpieces, some dark areas still cannot be covered by irradiation. For example, when irradiating circuit boards, there will be some narrow gaps and dark areas blocked by electronic components; 2. New high-efficiency photoinitiators enable photosensitive resins to continue to react to a certain extent after leaving the ultraviolet light irradiation, but the degree of reaction is low, the conversion rate is low, and the coating performance is poor; 3. Ultraviolet light-dark dual curing technology can better solve this defect of high dependence on ultraviolet light irradiation. When ultraviolet light cannot irradiate the dark corners, the coating continues to react in another form until it is cured into a film. The physical and chemical properties of the coating are better than those of coatings cured by single ultraviolet light.

[0004] Currently, there are three main types of UV-dark dual-curing systems: UV-thermal curing, UV-oxygen curing, and UV-moisture curing. UV-thermal curing systems typically introduce polymerization mechanisms containing hydroxyl and amino groups into the photosensitive resin system. Besides UV curing, the coating can also undergo condensation polymerization and cross-linking under heat to form a film. UV-oxygen curing systems introduce allyl ether compounds into the photosensitive resin. Besides UV curing, free radical polymerization can be initiated by the combined action of peroxides and oxygen. UV-moisture curing systems introduce siloxane or isocyanate structures into the photosensitive resin system, which react with moisture to undergo condensation reactions and cross-link to form a film. Among these three systems, UV-moisture curing is the most commonly used, as it is simpler to apply and generally more effective. However, when dual-curing coatings containing isocyanate groups are applied to electronic circuits, circuit boards for coating, pasting or encapsulation, they have defects such as poor adhesion, poor corrosion resistance, and easy sagging when thick coatings are applied. They also have poor electrical properties, such as low environmental insulation resistance of dual 85 coatings. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a dual-curing coating that, through the compounding of dual-curing polyurethane acrylate resin, γ-glycidylpropyltrimethoxysilane, rheology modifier, and other components, simultaneously improves the adhesion, corrosion resistance, sag resistance, and electrical properties of the dual-curing coating.

[0006] A second aspect of the present invention is to provide a method for preparing a dual-curing coating.

[0007] A third aspect of the present invention is to provide a dual-curing coating.

[0008] A fourth aspect of the present invention is to provide a method for preparing a dual-curing coating.

[0009] The fifth aspect of the present invention is to provide an application of a dual-curing coating or dual-curing coating layer.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A first aspect of the present invention provides a dual-curing coating, comprising, by weight parts:

[0012] 34-50 parts of dual-curing polyurethane acrylate resin,

[0013] 3-7 parts of trimethoxysilane containing epoxy groups,

[0014] 35-50 parts of reactive diluent

[0015] 3-8 parts of photoinitiator

[0016] 2-5 parts of dehydrating agent

[0017] Polymerization inhibitor 0.2-0.5 parts,

[0018] 0.5 to 2 parts of rheology modifier

[0019] Surfactant 0.5 to 1 part;

[0020] The dual-curing polyurethane acrylate resin contains isocyanate groups and alkenyl groups.

[0021] In this invention, dual curing refers to the ability of the coating to undergo both UV curing and moisture curing during the coating process.

[0022] This invention forms a hybrid structure by adding an epoxy-containing methoxysilane polymer. Due to the presence of multiple crosslinking reaction modes such as isocyanate group reaction, olefin bond reaction, and siloxy group reaction, the degree of crosslinking of the coating is increased, thereby improving the electrical properties and corrosion resistance of the coating. At the same time, the introduction of epoxy groups significantly improves the adhesion of the coating to the substrate, and the improved adhesion also enhances the corrosion resistance of the coating (or paint film). In addition, by adding a certain amount of rheology modifier, the coating does not sag when thickly coated (coating thickness greater than 100μm), improving the coverage of solder bumps and traces of electronic components on the circuit board, further improving the electrical properties and corrosion resistance.

[0023] The main components of the dual-curing coating of the present invention are further described below:

[0024] Dual-curing polyurethane acrylate resin is a polyurethane acrylate resin containing two different reactive groups. In this invention, it specifically refers to a polyurethane acrylate photosensitive resin containing isocyanate groups (-NCO) and olefin bonds (C=C). This type of resin can undergo free radical polymerization excited by ultraviolet light, or it can undergo addition polymerization through the reaction of isocyanate groups with moisture in the air. Therefore, by adding this dual-curing polyurethane acrylate resin, the resulting coating has a dual-curing effect. When the coating passes through an ultraviolet lamp, the exposed surface of the coating is activated and cured. After the coating leaves the ultraviolet lamp, the other cross-linking curing mechanism (the reaction of isocyanate with moisture in the air) continues, allowing the entire coating to reach a fully cross-linked state after a period of time.

[0025] In methoxysilanes containing epoxy groups, methoxysilanes can react with water vapor to generate silanols. The silanol molecules can then be dehydrated to generate polysiloxanes. The silanol molecules can also react with the isocyanate groups in the aforementioned dual-curing polyurethane acrylate resin to generate silanoamino isocyanates. Thus, a hybrid interpenetrating network polymer is generated. The polymer has a high degree of crosslinking, and the siloxane has a low surface energy. Therefore, the resulting polymer coating is not easily wetted or penetrated by water, thereby endowing the coating with good electrical properties and corrosion resistance. Moreover, the siloxane introduces epoxy groups, which have good adhesion to various inorganic and organic substrates. Therefore, the overall coating obtained by the coating has a high adhesion to various substrates.

[0026] Reactive diluents are acrylate monomers with olefin bonds (C=C). In coating formulations, they primarily function to reduce system viscosity, regulate reactivity, and decrease internal stress in the reaction products. The olefin bond (C=C) free radical polymerization of dual-curing polyurethane acrylate resins often has a rapid reaction rate. During cross-linking and curing to form the polymer, the resulting internal stress cannot be released in time and remains in the coating for a long period. Such coatings have poor adhesion to the substrate and may crack or detach under varying temperature conditions. Therefore, adding an appropriate amount of reactive diluent to regulate the overall reaction rate of the coating during curing is very helpful in improving coating adhesion and durability. Furthermore, due to the low viscosity of reactive diluents themselves, adding an appropriate amount can also reduce the overall viscosity of the coating, facilitating spraying or brushing applications.

[0027] The photoinitiator in this invention is excited when exposed to ultraviolet light and reacts with the C=C bonds in the dual-curing polyurethane acrylate resin or reactive diluent to form chain growth, and then further reacts to form a polymer, completing cross-linking and curing.

[0028] The addition of a polymerization inhibitor in this invention can suppress the self-polymerization tendency of resins or monomers in the coating system during storage, ensuring that the coating does not deteriorate or gel during the preset storage period. Furthermore, after the coating is applied as a film and the reaction is activated by ultraviolet light, the polymerization inhibitor is consumed within a very short time due to the appropriate amount added, and does not hinder the curing reaction.

[0029] Dehydrating agents are highly reactive substances that preferentially react with water. Since the main resin used in this invention is a dual-curing polyurethane acrylate resin containing isocyanate groups, its -NCO groups readily react with water. Therefore, a dehydrating agent needs to be added during coating formulation to remove moisture from the system. Simultaneously, the dehydrating agent also preferentially reacts with moisture that enters the packaging during coating storage, thus protecting the main resin from damage and maintaining the system's quality stability. After the coating is applied as a film, due to the appropriate dosage, the dehydrating agent, once consumed by moisture in the air, will not hinder the moisture-curing reaction of the film.

[0030] Rheology modifiers are additives that can alter the rheological properties of a system by forming intermolecular bonds with themselves or with materials in the system. Typically, adding these modifiers can induce pseudoplasticity in coatings, resulting in a shear-thinning effect. When the coating is applied, it is subjected to shear forces, causing it to thin and flow smoothly. Once the application force is removed, the viscosity of the system gradually increases under the influence of the rheology modifier, preventing the coating from dripping or sagging. This application characteristic is especially important in thick-film applications.

[0031] Surfactants help coatings spread and level after application, and eliminate air bubbles generated during production and application, ensuring a smooth and uniform coating.

[0032] In some embodiments of the present invention, the dual-curing coating comprises, by weight parts, the following components:

[0033] 34-49 parts of dual-curing polyurethane acrylate resin,

[0034] 3 to 6 parts of methoxysilane containing epoxy groups.

[0035] In some embodiments of the present invention, the dual-curing coating further comprises, by weight parts:

[0036] 38-49 parts of reactive diluent

[0037] 4-7 parts of photoinitiator

[0038] 2-4 parts of dehydrating agent

[0039] Polymerization inhibitor 0.2–0.4 parts,

[0040] 0.5–1.5 parts of rheology modifier,

[0041] Surfactant 0.6 to 1 part.

[0042] In some embodiments of the present invention, the mass ratio of the epoxy-containing methoxysilane to the dual-curing polyurethane acrylate resin is 1:(5-13).

[0043] In some embodiments of the present invention, the mass ratio of the epoxy-containing methoxysilane to the dual-curing polyurethane acrylate resin is 1:(5.5-12.5).

[0044] In some specific embodiments of the present invention, the mass ratio of the epoxy-containing methoxysilane to the dual-curing polyurethane acrylate resin is 1:(9-12).

[0045] In some embodiments of the present invention, the mass content of isocyanate groups in the dual-curing polyurethane acrylic resin is 7-11%.

[0046] In some embodiments of the present invention, the mass content of isocyanate groups in the dual-curing polyurethane acrylic resin is 7.5% to 10.5%.

[0047] In some embodiments of the present invention, the non-volatile content of the dual-curing polyurethane acrylic resin is ≥98%.

[0048] In some embodiments of the present invention, the non-volatile content of the dual-cured polyurethane acrylic resin is 98-100%.

[0049] In some embodiments of the present invention, the acid value of the dual-curing polyurethane acrylic resin is ≤5 mg KOH / g.

[0050] In some embodiments of the present invention, the refractive index of the dual-cured polyurethane acrylic resin is 1 to 2.

[0051] In some embodiments of the present invention, the dual-curing polyurethane acrylic resin includes at least one of the following: PJ9880-100 UV dual-curing resin from Jiangmen Paint Factory Co., Ltd., L-8460 moisture-curing UV polyurethane resin from Lankel Road, and ETERCURE6133N-10 UV moisture-curing dual-curing resin from Changxing.

[0052] In terms of environmental protection, this invention further uses a main resin with a non-volatile content of nearly 100%, and the added monomers are also non-volatile components. Therefore, the formula ensures that the non-volatile content of the finished product is above 98%, and the volatile organic compound (VOC) content is extremely low, which meets the requirements of my country's green and environmentally friendly products.

[0053] In some embodiments of the present invention, the epoxy-containing methoxysilane includes γ-glycidylpropyltrimethoxysilane.

[0054] In some embodiments of the present invention, the photoinitiator is sensitive to ultraviolet light at 365 nm and / or 395 nm.

[0055] In some embodiments of the present invention, the photoinitiator is a free radical type photoinitiator.

[0056] When exposed to ultraviolet light, free radical photoinitiators are excited into free radical actives, which react with the C=C bonds in dual-curing polyurethane acrylate resins or reactive diluents to form chain growth, and then further react to form polymers.

[0057] In some embodiments of the present invention, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycycloethylphenylacetone.

[0058] In some embodiments of the present invention, the rheology modifier includes at least one of polyamide wax, bentonite, and fumed silica.

[0059] In some embodiments of the present invention, the polymerization inhibitor includes at least one of 1,1-diphenyl-2-trinitrophenylhydrazine and p-methoxyphenol.

[0060] In some embodiments of the present invention, the reactive diluent includes at least one of isobornyl acrylate, tricyclodecanediol diacrylate, 2-phenoxyethyl acrylate, and cyclotrimethylolpropane methyl acetal acrylate.

[0061] In some embodiments of the present invention, the dual-curing coating is filtered through a 200-mesh filter during the preparation process. Filtration removes particulate impurities from the coating.

[0062] A second aspect of the present invention provides a method for preparing the dual-curing coating described in the first aspect of the present invention, comprising the following steps:

[0063] After mixing the components, the mixture is filtered to obtain a dual-curing coating.

[0064] In some embodiments of the present invention, the components other than the dual-curing polyurethane acrylate resin and γ-glycidyl ether propyltrimethoxysilane are first mixed, and then the dual-curing polyurethane acrylate resin and γ-glycidyl ether propyltrimethoxysilane are added and mixed.

[0065] In some embodiments of the present invention, the components other than the dual-curing polyurethane acrylate resin and γ-glycidyl ether propyltrimethoxysilane are first mixed and dispersed at high speed; the rotation speed of the high-speed mixing and dispersion is 2000-3000 r / min.

[0066] In some embodiments of the present invention, the addition of dual-curing polyurethane acrylate resin and γ-glycidyl ether propyltrimethoxysilane for mixing is a medium-low speed mixing and dispersion; the rotation speed of the medium-low speed mixing and dispersion is 300-500 r / min.

[0067] In some embodiments of the present invention, the high-speed mixing and dispersion time is 20 to 30 minutes.

[0068] In some embodiments of the present invention, the medium-low speed mixing and dispersion time is 10 to 15 minutes.

[0069] A third aspect of the present invention provides a dual-curing coating, wherein the raw materials for preparing the coating include the coating described in the first aspect of the present invention.

[0070] In some embodiments of the present invention, the thickness of the coating is 90–180 μm.

[0071] In some embodiments of the present invention, the thickness of the coating is 90–175 μm.

[0072] A fourth aspect of the present invention provides a method for preparing the dual-curing coating described in the third aspect of the present invention, comprising the following steps:

[0073] The coating formed after the paint is applied is placed under ultraviolet light for ultraviolet curing, and after the ultraviolet light is removed, moisture curing is continued to obtain a double-cured coating.

[0074] The coating includes the dual-curing coating described in the first aspect of the present invention.

[0075] The fifth aspect of the present invention provides an application of the dual-curing coating described in the first aspect of the present invention or the coating described in the third aspect of the present invention in the fields of plastics, wood, metal coils, electronic appliances, and circuit boards.

[0076] In some embodiments of the present invention, the dual-curing coating is used for coating electronic appliances and circuit boards.

[0077] The UV-moisture curing system technology employed in this invention is highly suitable for protective coating of electronic appliances and circuit boards. Unlike conventional UV-moisture curing systems, this invention uses a dual-curing polyurethane acrylate photosensitive resin containing isocyanate groups and olefin bonds as the main resin, compounded with epoxy-containing methoxysilanes to form a hybrid system. This system can undergo free radical polymerization excited by UV light, or polymerization through the reaction of isocyanate groups and methoxysilanes with water. This polymer combines the advantages of acrylate resins, polyurethane resins, siloxane resins, and epoxy resins. The hybrid UV-moisture dual-curing coating prepared with this formulation is highly suitable for coating irregularly shaped workpieces with complex light / dark surfaces, such as circuit boards. It features uniform curing speed, strong adhesion, superior electrical properties, strong corrosion resistance, and non-sagging even with thick coatings, ensuring the overall electrical and corrosion resistance of the circuit board (including both light and dark surfaces).

[0078] In some embodiments of the present invention, the dual-curing coating is used for coating, pasting, or encapsulating plastics, wood, metal coils, electronic appliances, and circuit boards.

[0079] Compared with the prior art, the present invention has at least the following beneficial effects:

[0080] (1) This invention uses a dual-curing polyurethane acrylate photosensitive resin containing isocyanate groups and olefin bonds as the main resin, and combines it with methoxysilane containing epoxy groups to form a hybrid system. The resulting coating can be polymerized by free radical polymerization excited by ultraviolet light, or by polymerization through the reaction of isocyanate groups and methoxysilane with water. It combines the advantages of acrylate resin, polyurethane resin, siloxane resin and epoxy resin, and has the characteristics of uniform curing speed, strong adhesion, excellent electrical properties, strong corrosion resistance, no sagging when thick coating, good storage stability and easy spraying.

[0081] (2) This invention forms a hybrid structure by adding an epoxy-containing methoxysilane polymer. Due to the presence of multiple crosslinking reaction modes such as isocyanate group reaction, olefin bond reaction, and siloxy group reaction, the degree of crosslinking of the coating is increased, thereby improving the electrical properties and corrosion resistance of the coating. At the same time, due to the introduction of epoxy groups, the adhesion of the coating to the substrate is significantly improved, solving the adhesion problem for different types of circuit boards. The improved adhesion also enhances the corrosion resistance of the coating. In addition, the addition of a specific amount of rheology modifier prevents sagging when the coating is applied in a thick coat.

[0082] (3) The coating obtained by the present invention has the characteristics of uniform curing speed, strong adhesion, excellent electrical properties, strong corrosion resistance, thick coating without sagging, good storage stability and easy spraying. It has high adhesion to different types of circuit boards, improves the coverage of solder bumps and traces of electronic components in electronic appliances or circuit boards, and improves electrical performance and corrosion resistance. Detailed Implementation

[0083] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0084] The following describes some of the raw materials used in the following embodiments and comparative examples of the present invention:

[0085] Dual-curing polyurethane acrylate resins: PJ9880-100UV dual-curing resin (Jiangmen Paint Factory Co., Ltd.); L-8460 moisture-curing UV polyurethane resin (Lankelu New Materials Co., Ltd.); ETERCURE 6133N-10UV moisture-curing dual-curing resin (Changxing Special Materials Suzhou Co., Ltd.); all have non-volatile content ≥98%, NCO content 7.5~10.5%, acid value ≤5mg KOH / g, and refractive index 1~2.

[0086] γ-glycidyl ether propyltrimethoxysilane: XIAMETER OFS-6040 silane (Dow Corning); KH-560 silane (commercially available).

[0087] Dehydrating agents: Additive TI (Boshes Chemical); Additive OF (Boshes Chemical).

[0088] Rheology modifiers: 6900-HV polyamide wax (DISPARLON); TS-610 fumed silica (Cabot Corporation).

[0089] Surfactants: BYK-UV 3575 (BYK Chemicals); TEGO Rad 2550 (Evonik Chemicals); TEGO Airex-920 (Evonik Chemicals); BYK-1799 (BYK Chemicals).

[0090] Polyurethane acrylate resin: EBECRYL 264 aliphatic polyurethane acrylate (Germany).

[0091] Examples 1-5

[0092] Examples 1-5 provide a dual-curing coating, the formulation of which is shown in Table 1 below:

[0093] Table 1. Formulation table of dual-curing coatings for Examples 1-5 (parts by weight)

[0094]

[0095]

[0096] The preparation method of the dual-curing coatings in Examples 1-5 can be referred to the following steps:

[0097] S1. Add reactive diluent, photoinitiator, dehydrating agent, polymerization inhibitor, rheology modifier, and surfactant sequentially to the paint mixing tank, disperse at high speed (2000 r / min) for 30 min;

[0098] S2. Next, add dual-curing polyurethane acrylate resin and γ-glycidyl ether propyltrimethoxysilane in sequence, disperse at medium to low speed, 300 r / min, for 15 min;

[0099] S3. Filter the finished product using a 200-mesh filter.

[0100] The rotational speed and dispersion time for steps S1 and S2 in Examples 1-5 are shown in Table 2 below:

[0101] Table 2. Mixing and Dispersion Parameters of Examples 1-5

[0102] Step S1 Rotational speed 2000r / min 3000r / min 2300r / min 2300r / min 2800r / min Step S1 Dispersion Time 30min 20min 27min 27min 21min Step S2 Rotational speed 300r / min 500r / min 370r / min 370r / min 470r / min Step S2 Dispersion Time 15min 10min 14min 14min 11min

[0103] Comparative Examples 1-8

[0104] Comparative Examples 1-8 provide a coating with the formulation shown in Table 3:

[0105] Table 3. Coating formulations (parts by weight) for Comparative Examples 1–8

[0106]

[0107] The preparation process of the coatings in Comparative Examples 1 to 6 was the same as that in Example 1, and the preparation process of the coatings in Comparative Examples 7 to 8 was the same as that in Example 3.

[0108] Result detection

[0109] The coatings and coatings obtained in the above embodiments and comparative examples were subjected to performance tests.

[0110] The performance indicators of the dry film coating include adhesion, dielectric withstand voltage, volume resistivity, double 85 environmental insulation resistance, alkali resistance, acid resistance, and salt spray resistance. The dry film coating is prepared by spraying the coating onto a sample using an air-assisted spray gun, achieving a wet film thickness of 100±10 μm. The sample is then irradiated with a UV lamp of 365 nm or 395 nm for 10 seconds, and then allowed to dry naturally at room temperature for 168 hours before testing. The remaining items are coating performance indicators.

[0111] The specific testing methods are as follows:

[0112] Dryness: Test standard: GB / T1728-2020 Method B (UV lamp with wavelength of 365nm or 395nm, power density of 80~120W / cm, irradiation for 10 seconds, then left to stand naturally for 24 hours); Index requirements: the surface should be dry on the light side after irradiation for 10 seconds, and the surface should be dry on the dark side after being left to stand naturally for 24 hours.

[0113] Adhesion (cross-cut test): Test standard: GB / T 9286-2021; Index requirement: ≤ Grade 1.

[0114] Dielectric withstand voltage: Test standard: GB / T 1981.2-2009; Specification requirements: Leakage current should be <10μA at 1500Vac, and there should be no discharge phenomenon.

[0115] Volume resistivity: Test standard: HG / T 3331-2012; Requirement: ≥1×10⁻⁶ 13 Ω·cm.

[0116] Double 85 environmental insulation resistance: Test standard: GB / T 2423.50-2012 (temperature 85±2℃, humidity 85±2%, placed for 168h, then placed at room temperature for 24h before testing insulation resistance); Index requirement: ≥5000MΩ.

[0117] Alkali resistance (5% Na2CO3, 72h): Test standard: GB 9274-1988; Indicator requirements: No corrosion, white spots, blistering, discoloration, pinholes, cracks, fine cracks, wrinkling, loss of gloss, etc.

[0118] Acid resistance (5% NH4Cl, 72h): Test standard: GB 9274-1988; Indicator requirements: No corrosion, white spots, blistering, discoloration, pinholes, cracks, fine cracks, wrinkling, loss of gloss, etc.

[0119] Salt spray resistance (neutral salt spray, 192h): Test standard: GB / T 1771-2007; Indicator requirements: no blistering, rust spots, creep, whitening, blackening, greening, peeling, or separation.

[0120] Anti-sagging test: Test standard: GB / T 9264-2012; Index requirement: wet film ≥100μm.

[0121] Storage stability: Test standard GB 6753.3-1986; Index requirement: ≥8 level.

[0122] Sprayability: Test standard: The paint is sprayed onto the sample using an air-assisted spray gun at an air pressure of 0.5 kg / cm². 2 Specification requirements: Easy to spray.

[0123] The results are shown in Tables 4 and 5 below:

[0124] Table 4. Performance Comparison of Dual-Cure Coatings in Examples

[0125]

[0126]

[0127] Table 5. Comparison of Coating Performance in Comparative Examples

[0128]

[0129]

[0130] Combining Tables 4 and 5, it can be seen that the hybrid UV-moisture dual-curing coatings obtained according to the formulations of this invention in Examples 1-5 fully meet the performance requirements of conformal coatings for circuit boards, and also meet the application requirements of the circuit board industry in terms of drying properties on both light and dark sides, anti-sagging thickness, and sprayability. Comparative Examples 1-8 were adjusted in terms of silane, dehydrating agent, rheology modifier, polymerization inhibitor, main film-forming resin type, amount of dual-curing polyurethane acrylate resin added, and amount of γ-glycidyl ether propyltrimethoxysilane added. Performance testing results show that Comparative Examples 1-8 exhibited one or more non-compliant items in performance indicators such as adhesion, salt spray resistance, storage stability, anti-sagging test, drying properties, double 85 environmental insulation resistance, acid resistance, and volume resistivity.

[0131] The difference between Comparative Example 1 and Example 1 is that γ-glycidyl ether propyltrimethoxysilane (XIAMETER OFS-6040 silane) was not added. Other components, proportions, and manufacturing processes were the same as in Example 1. However, the coating obtained by the preparation of the coating had significantly worse adhesion (cross-cut test) and reached level 4. It also showed corrosion after 48 hours of salt spray resistance, which did not meet the requirements.

[0132] The difference between Comparative Example 2 and Example 1 is that no water-removing agent (Additive TI) was added. Other components, proportions, and manufacturing processes were the same as in Example 1. However, the resulting coating had poor storage stability and a short shelf life, gelling after 7 days, which did not meet the requirements.

[0133] The difference between Comparative Example 3 and Example 1 is that no rheology modifier (6900-HV polyamide wax and TS-610 fumed silica) was added. Other components, proportions, and manufacturing processes were the same as in Example 1. However, when the coating was tested for anti-sagging, the anti-sagging limit thickness was low, only 50 μm, which did not meet the requirements.

[0134] The difference between Comparative Example 4 and Example 1 is that no polymerization inhibitor (1,1-diphenyl-2-trinitrophenylhydrazine) was added. The other components, proportions, and manufacturing process were the same as in Example 1. However, the resulting coating had poor storage stability and a short shelf life, gelling after 14 days, which did not meet the requirements.

[0135] The difference between Comparative Example 5 and Example 1 is that ordinary polyurethane acrylate resin was used instead of dual-curing polyurethane acrylate resin. Other components, proportions, and manufacturing processes were the same as in Example 1. After the resulting coating formed a film, its drying properties deteriorated, with dark areas not drying completely; adhesion was poor, only at level 3; and the volume resistivity was only 2.56 × 10⁻⁶.11 The insulation resistance in a dual 85 environment is only 280 MΩ·cm, indicating poor electrical properties; it shows corrosion after 24 hours of acid resistance and 48 hours of salt spray resistance; these properties do not meet the requirements. Conventional polyurethane acrylates do not contain active isocyanate groups; the isocyanate groups in their monomers have all reacted to transform into urethane structures and no longer have reactivity, therefore they do not have a dual-curing effect.

[0136] The difference between Comparative Example 6 and Example 1 is that the amount of PJ9880-100UV dual-curing resin added is higher, while the amount of reactive diluent added is lower. Other components, proportions, and manufacturing processes are the same as in Example 1. However, the resulting coating has poor sprayability, is difficult to spray, and does not meet the requirements.

[0137] The difference between Comparative Example 7 and Example 3 is that the amount of dual-curing polyurethane acrylate resin added is less, while the amount of γ-glycidyl ether propyltrimethoxysilane added is higher. Other components, proportions, and manufacturing processes are the same as in Example 3. However, after the coating is formed, the adhesion is only level 2, and white spots appear after 120 hours of salt spray resistance, which does not meet the requirements.

[0138] The difference between Comparative Example 8 and Example 3 is that the amount of γ-glycidyl ether propyltrimethoxysilane added is lower. Other components, proportions, and manufacturing processes are the same as in Example 3. However, after the coating is formed, white spots appear in the salt spray resistance after 168 hours, and the corrosion resistance does not meet the requirements.

[0139] It is evident that the hybrid UV-moisture dual-curing coating obtained according to the formulation specified in this invention has the characteristics of uniform curing speed, strong adhesion, excellent electrical properties, strong corrosion resistance, no sagging when applied in thick coating, good storage stability and easy spraying. It can be practically applied to coating in the plastics, wood, metal coils, electronics and electrical appliances and circuit board industries, especially in the circuit board industry.

[0140] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A dual-curing coating, characterized in that, By mass, it consists of the following components: 34-49 parts of dual-curing polyurethane acrylate resin, 3-6 parts of epoxy-containing methoxysilanes 38-49 parts of reactive diluent 4-7 parts of photoinitiator 2-4 parts of dehydrating agent Polymerization inhibitor 0.2~0.4 parts, 0.5 to 1.5 parts of rheology modifier. Surfactant 0.6~1 part; The dual-curing polyurethane acrylate resin contains isocyanate groups and alkenyl groups; The epoxy-containing methoxysilanes include γ-glycidylpropyltrimethoxysilane; The mass ratio of the epoxy-containing methoxysilane to the dual-curing polyurethane acrylate resin is 1:(5~13). The mass content of isocyanate groups in the dual-curing polyurethane acrylic resin is 7-11%; The dual-curing polyurethane acrylic resin is selected from at least one of the following: PJ9880-100 UV dual-curing resin from Jiangmen Paint Factory Co., Ltd., L-8460 moisture-curing UV polyurethane resin from Lankel Road, and ETERCURE6133N-10 UV moisture-curing dual-curing resin from Changxing.

2. The dual-curing coating according to claim 1, characterized in that, The photoinitiator is sensitive to ultraviolet light at 365 nm and / or 395 nm. And / or, the photoinitiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycycloethylphenylacetone.

3. The dual-curing coating according to claim 1, characterized in that, The rheology modifier includes at least one of polyamide wax, bentonite, and fumed silica. And / or, the polymerization inhibitor includes at least one of 1,1-diphenyl-2-trinitrophenylhydrazine and p-methoxyphenol; And / or, the reactive diluent includes at least one of isoborneol acrylate, tricyclodecanediol diacrylate, 2-phenoxyethyl acrylate, and cyclotrimethylolpropane methyl acetal acrylate.

4. A method for preparing the dual-curing coating according to any one of claims 1 to 3, characterized in that, Includes the following steps: After mixing the components, the mixture is filtered to obtain a dual-curing coating.

5. A dual-curing coating, characterized in that, The raw materials for preparing the coating include the dual-curing coating as described in any one of claims 1 to 3.

6. A method for preparing the dual-curing coating as described in claim 5, characterized in that, Includes the following steps: The coating formed after the paint is applied is placed under ultraviolet light for ultraviolet curing, and after the ultraviolet light is removed, moisture curing is continued to obtain a double-cured coating. The coating includes the dual-curing coating as described in any one of claims 1 to 3.

7. The application of a dual-curing coating according to any one of claims 1 to 3 or a dual-curing coating according to claim 6 in the fields of plastics, wood, metal coils, electronic appliances, and circuit boards.

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