High-performance uv cushion plate and preparation process thereof

Abstract

The application discloses a kind of high-performance UV backing plate and its preparation process, including wood fiber plate core layer, putty layer, primer layer and finish layer, the putty layer is shrunk by 2~3% after UV curing, the primer layer is 30~50% after UV curing and the shrinkage is 5~8%, the putty layer is delayed curing using light base system, after first UV semi-curing by roll coating and coating on the wood fiber plate core layer, after coating the primer layer, it is cured again, the equivalent expansion effect formed by the shrinkage difference of the putty layer and the primer layer improves the poor embedding adhesion effect of the putty layer and the wood fiber plate core layer, finally, the finish layer with low shrinkage is coated on the primer layer. High adhesion, high flatness UV backing plate is prepared by the application.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing, and more specifically to a high-performance UV board and its preparation process. Background Technology

[0002] A backing plate is a material placed under the board to be processed during mechanical drilling of printed circuit boards (PCBs) to meet the processing requirements. The main functions of the backing plate are: (1) reducing burrs at the drill hole opening of the substrate; (2) protecting the drilling machine table for drilling through the PCB; (3) reducing drill bit temperature and reducing drill bit wear; (4) cleaning some of the drill residue on the drill bit; and (5) playing a certain role in positioning and improving drilling accuracy.

[0003] Commonly used PCB backing boards include: high-density wood backing boards, phenolic wood backing boards, melamine wood backing boards, phenolic paper backing boards, high-density fiberboard, and aluminum foil composite wood backing boards. Different materials provide different functions, such as high hardness, heat dissipation, low cost, and environmental friendliness. For backing boards using wood fiber as the substrate, different face-mounted backing board products are mainly provided through the design of the overlay layer, such as UV-cured topcoat, paper overlay, etc. These products are characterized by low cost and environmental friendliness. Related existing technologies include:

[0004] CN201510987837.4 discloses a PCB drilling pad and its preparation method. The pad includes a wood fiberboard and an ultraviolet radiation curable resin layer coated on the upper and lower surfaces of the wood fiberboard. The ultraviolet radiation curable resin layer has the property of being cured by an LED ultraviolet radiation curing lamp. The pad of the present invention, after being cured by an LED ultraviolet radiation curing lamp, has advantages such as less warpage, higher flatness, more acceptable appearance, minimal odor, higher hardness, longer service life, and environmental friendliness.

[0005] CN201510191340.1 discloses a PCB drilling pad and its manufacturing method, comprising the following steps: adding 50-70% phenolic epoxy acrylic resin, 20-50% filler, and 0-10% diluent sequentially to a mixing tank by weight, heating to 40-60°C, stirring and mixing for 30-60 minutes, adding 0.5-5% photoinitiator, continuing stirring for 10-15 minutes, cooling and discharging to obtain a composite resin; using a wood fiberboard as a substrate, coating the upper and lower surfaces of the substrate with the above-obtained composite resin, and curing under predetermined conditions to form a pad. The PCB drilling pad of this invention has significantly improved surface hardness and effectively reduces burrs generated during drilling, thereby improving the production efficiency of PCB drilling.

[0006] In the existing technology, free radical acrylate UV curing has a large market, but it suffers from problems such as poor solvent resistance, high shrinkage, oxygen inhibition, and high stress at the adhesive interface. Cationic UV delayed-curing adhesives can achieve delayed curing and reduce shrinkage, but the problem of high stress at the adhesive interface still exists. Therefore, how to solve the conflict between UV curing adhesion and stress on wood fiberboard substrates and improve the stress state is the direction of this invention. Summary of the Invention

[0007] To address the problems in related technologies, this invention proposes a high-adhesion UV pad and its preparation process to overcome the aforementioned technical problems existing in the prior art.

[0008] The technical solution of this invention is implemented as follows: a delayed-curing putty layer is designed, and a high-shrinkage primer layer is coated on the semi-cured putty layer to form a double-layer structure with a difference in UV curing shrinkage. Then, the putty layer and primer layer are completely cured again with UV light. The equivalent expansion of the putty layer caused by the difference in shrinkage is used to increase the interlocking degree in the wood fiberboard voids. Finally, a topcoat is applied. In this invention, the material shrinkage rate and crosslinking degree of the putty layer, primer layer, and topcoat layer are controlled by changing the resin substrate, selecting different functional group active monomers and additives to improve the overall performance of the coating.

[0009] The specific details of the invention are as follows:

[0010] A high-performance UV pad and its preparation process include a wood fiberboard core layer, a putty layer, a primer layer and a topcoat layer arranged sequentially from the inside out. The putty layer material contains a UV curing delay agent, and the curing shrinkage rate of the primer layer is greater than that of the putty layer.

[0011] Preferably, the wood fiberboard core layer of the high-performance UV pad has a thickness of 2.4 to 2.5 mm.

[0012] Preferably, the total coating thickness of the high-performance UV pad is 50–80 μm.

[0013] More preferably, the thickness of the primer layer is less than the thickness of the putty layer.

[0014] Preferably, the photocuring delay agent is a photoalkali-generating agent system.

[0015] Preferably, the shrinkage rate of the putty layer is 2-3%, the shrinkage rate of the primer layer is 5-8%, and the shrinkage rate of the topcoat layer is 3-5%.

[0016] Preferably, the UV transmittance of the primer layer after complete curing is 30-50%.

[0017] Preferably, the Shore D hardness of the high-performance UV pad is greater than 80±3 N / mm. 2.

[0018] Preferably, the density of the high-performance UV pad is between 880 and 920 kg / mm². 3 .

[0019] Preferably, the surface of the high-performance UV pad is white.

[0020] Preferably, the manufacturing process of the high-performance UV pad includes the following steps:

[0021] S1: The surface of the wood fiberboard core layer is coated with a 20-30 μm thick putty layer, and then semi-cured under 320-365 nm UV light for 10-30 seconds to prepare substrate A, with a curing energy of 250-300 mW / cm². 2 ;

[0022] S2: A primer layer of 10–20 μm is coated onto substrate A, and substrate B is prepared by complete curing under 320–365 nm UV light for 40–60 seconds, with a curing energy of 150–200 mW / cm². 2 ;

[0023] S3: The substrate B is coated with a 20-30 μm thick topcoat layer, and then completely cured under 320-365 nm UV light for 40-60 seconds to prepare the high-performance UV pad. The curing energy is 200-300 mW / cm². 2 .

[0024] Preferably, the coating method is roller coating.

[0025] More preferably, the roller coating method involves first applying the coating with a rubber roller and then smoothing it with an anilox roller.

[0026] The specific contents of the invention regarding the composition, preparation process, and coating method of the putty layer, primer layer, and topcoat layer are as follows:

[0027] (1) The composition, preparation and application of the putty layer

[0028] Preferably, the material composition of the putty layer is: 20-30 parts epoxy resin, 25-40 parts acrylate, 10-20 parts active monomer, 2-4 parts photoinitiator, 1-3 parts photocuring retarder, 1-3 parts polyfunctional thiols, 20-50 parts filler, and 0-5 parts other additives.

[0029] Preferably, the epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and alicyclic epoxy resin.

[0030] Preferably, the acrylate material is an epoxy resin modified acrylate.

[0031] More preferably, the epoxy-modified acrylate is a bisphenol A-modified acrylate.

[0032] Preferably, the active monomer is a monofunctional acrylate.

[0033] More preferably, the monofunctional acrylate is one or more of β-hydroxyethyl methacrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, and tetrahydrofurfuryl acrylate.

[0034] Preferably, the photoinitiator is one or more of methyl benzoylformate, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0035] Preferably, the photocuring delay agent is a photoalkali-generating agent.

[0036] More preferably, the photocuring retarder is one or more of the following: carbamates, carboxylates, borates, quaternary ammonium salts, and benzylamidines.

[0037] More preferably, the photocuring retarder is one or more of tetraphenylborane guanidine, 1,1,3,3,-tetramethylguanidine, and tetraphenylborane quaternary ammonium salt.

[0038] Preferably, the polyfunctional thiol is one or more of pentaerythritol tetra-3-mercaptopropionate, trihydroxypropane (3-mercaptopropionate), di(3-mercaptopropionic acid) ethylene glycol ester, trimethylolpropane tris(2-mercaptoacetic acid), dimercaptoacetic acid diethanolate, and ethoxytrimethylolpropane tris(3-mercaptopropionic acid) ester.

[0039] Preferably, the ratio of the photoinitiator to the photocuring delay agent is 1:0.5 to 0.8.

[0040] Preferably, the other additives are one or more of the following: 0.5 to 1.5 parts of dispersant, 0.1 to 0.5 parts of defoamer, and 0.01 to 1.0 parts of leveling agent.

[0041] Preferably, the dispersant is a polymeric dispersant, the leveling agent is an organosilicon leveling agent, and the defoamer is an organosilicon defoamer or a polyether defoamer.

[0042] More preferably, the defoamer is one of silicone oil and polyethylene oxide alcohol.

[0043] More preferably, the dispersant is one or more of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, isomeric alcohol polyoxypropylene ether, and isomeric alcohol polyoxyethylene polyoxypropylene ether.

[0044] More preferably, the leveling agent is one or more of diethylene glycol butyl ether, diethylene glycol dibutyl ether, and triethylene glycol butyl ether.

[0045] Preferably, the filler is one or more of silicon dioxide, glass microspheres, titanium dioxide, talc, and aluminum hydroxide.

[0046] Preferably, the method for preparing the putty layer coating is as follows:

[0047] S1: Mix epoxy resin, multifunctional thiol and photocuring delay agent, heat at 80-100℃, stir for 30-40 minutes, and cool to 50-60℃.

[0048] S2: Add acrylate and active monomer, heat at 50-60℃, and stir for 30-40 minutes until homogeneous;

[0049] S2: Add filler and stir evenly for 50-60 minutes;

[0050] S3: Add photoinitiator and other additives, stir for 20-30 minutes, and degas under vacuum.

[0051] Preferably, the stirring speed is 1300-1500 r / min.

[0052] (2) The composition, preparation and coating of the primer layer

[0053] Preferably, the material composition of the primer layer is: 50-70 parts acrylate, 10-20 parts reactive monomer, 2-4 parts photoinitiator, 5-10 parts filler, and 0-5 parts other additives.

[0054] Preferably, the acrylate material is one or more of bisphenol A acrylate, polyester acrylate, and polyurethane acrylate.

[0055] Preferably, the active monomer is a multifunctional acrylate.

[0056] More preferably, the active monomer is one or more of pentaerythritol tetraacrylate, pentaerythritol tetraacrylate ethoxylate, di-trimethylolpropane tetraacrylate, and dipentaerythritol pentaacrylate.

[0057] Preferably, the photoinitiator is one or more of methyl benzoylformate, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0058] Preferably, the other additives are one or more of the following: 0.5 to 1.5 parts of dispersant, 0.1 to 0.5 parts of defoamer, and 0.01 to 1.0 parts of leveling agent.

[0059] Preferably, the dispersant is a polymeric dispersant, the leveling agent is an organosilicon leveling agent, and the defoamer is an organosilicon defoamer or a polyether defoamer.

[0060] More preferably, the defoamer is one of silicone oil and polyethylene oxide alcohol.

[0061] More preferably, the dispersant is one or more of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, isomeric alcohol polyoxypropylene ether, and isomeric alcohol polyoxyethylene polyoxypropylene ether.

[0062] More preferably, the leveling agent is one or more of diethylene glycol butyl ether, diethylene glycol dibutyl ether, and triethylene glycol butyl ether.

[0063] More preferably, the filler is one or more of the following: silicon dioxide, glass microspheres, titanium dioxide, talc, and aluminum hydroxide.

[0064] Preferably, the preparation method of the primer coating is as follows:

[0065] S1: Mix acrylate and active monomer, heat at 50-60℃, and stir until homogeneous for 30-40 minutes;

[0066] S2: Add filler and stir evenly for 50-60 minutes;

[0067] S3: Add photoinitiator and other additives, stir for 20-30 minutes, and degas under vacuum.

[0068] Preferably, the stirring speed is 1100-1300 r / min.

[0069] (3) The composition, preparation and application of the topcoat layer

[0070] Preferably, the material composition of the topcoat layer is: 50-70 parts acrylate, 15-25 parts reactive monomer, 2-4 parts photoinitiator, 20-30 parts filler, and 0-5 parts other additives.

[0071] Preferably, the acrylate material is one or more of bisphenol A acrylate, polyester acrylate, and polyurethane acrylate.

[0072] Preferably, the active monomer is a bifunctional acrylate.

[0073] More preferably, the active monomer is one or more of 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate.

[0074] Preferably, the photoinitiator is one or more of methyl benzoylformate, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0075] Preferably, the other additives are one or more of the following: 0.5 to 1.5 parts of dispersant, 0.1 to 0.5 parts of defoamer, and 0.01 to 1.0 parts of leveling agent.

[0076] Preferably, the dispersant is a polymeric dispersant, the leveling agent is an organosilicon leveling agent, and the defoamer is an organosilicon defoamer or a polyether defoamer.

[0077] More preferably, the dispersant is one or more of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, isomeric alcohol polyoxypropylene ether, and isomeric alcohol polyoxyethylene polyoxypropylene ether.

[0078] More preferably, the leveling agent is one or more of diethylene glycol butyl ether, diethylene glycol dibutyl ether, and triethylene glycol butyl ether.

[0079] More preferably, the filler is one or more of the following: silicon dioxide, glass microspheres, titanium dioxide, talc, and aluminum hydroxide.

[0080] Preferably, the other additives also include 1 to 5 parts of matting powder.

[0081] More preferably, the matting agent is one or more of organic-modified fumed silica.

[0082] Preferably, the preparation method of the topcoat layer is as follows:

[0083] S1: Mix acrylate and active monomer, heat at 50-60℃, and stir until homogeneous for 30-40 minutes;

[0084] S2: Add filler and stir evenly for 50-60 minutes;

[0085] S3: Add photoinitiator and other additives, stir for 20-30 minutes, and degas under vacuum.

[0086] Preferably, the stirring speed is 1100-1300 r / min.

[0087] Preferably, the filler used in the putty layer, primer layer and topcoat layer has a particle size of 200 to 300 mesh.

[0088] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0089] By preparing putty and primer layers with different shrinkage rates, the putty layer achieves an equivalent expansion effect. By delaying curing, the adhesion between the putty layer and the wood fiberboard core layer is increased, thereby improving the adhesion of the UV pad and improving the warping and flatness of the UV pad.

[0090] By adjusting the shrinkage rate and crosslinking degree through differences in resin matrix, functionality of active monomers, and photoinitiator used in different layers, a structure is achieved where the internal stress of the putty layer is minimized, the internal stress of the topcoat layer is next, and the internal stress of the primer layer is the greatest. This structure with varying internal stress improves the drilling and cutting quality. Attached Figure Description

[0091] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0092] Figure 1 This is a schematic diagram of the structure of the UV pad of the present invention.

[0093] Figure 2 This is a schematic diagram of the stress-strain curves of the primer coatings prepared from different functional group active monomers of the present invention.

[0094] Among them, 1 is the wood fiberboard core layer, 2 is the low shrinkage putty layer, 3 is the high shrinkage primer layer, and 4 is the medium shrinkage topcoat layer. Detailed Implementation

[0095] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0096] In a specific embodiment of the present invention, the epoxy resin used has a molecular weight of 3000-4000, the polyurethane acrylate has a molecular weight of 4000-5000, the polyester acrylate has a molecular weight of 2000-3000, and the filler has a D50 particle size of 200 mesh.

[0097] Example 1, Preparation of UV Pad 1

[0098] Putty layer 2 coating preparation steps:

[0099] S1: Mix 30 parts of bisphenol A epoxy resin, 2 parts of diethanol glycol dimercaptoacetate and 2 parts of tetraphenylborane guanidine, heat in a mixing tank at 80°C, stir at 1400 r / min for 30 min, and then cool to 50°C.

[0100] S2: Add 30 parts of bisphenol A modified acrylate and 15 parts of isoborneol acrylate, stir at 50℃ for 35 min, stirring speed 1500 r / min;

[0101] S3: Add 40 parts of talc powder and stir at 1500r / min for 60min;

[0102] S4: Add 3 parts of 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, 1 part of fatty alcohol polyoxyethylene ether, 1 part of diethylene glycol butyl ether, and 0.3 parts of silicone oil. Stir at 1300 r / min for 30 min, degas under vacuum, and the putty coating is ready.

[0103] Preparation steps for primer layer 3:

[0104] S1: Mix 40 parts of epoxy-modified acrylate, 20 parts of polyurethane acrylate, and 15 parts of pentaerythritol tetraacrylate. Heat the mixture in a mixing tank at 55°C and stir at 1100 r / min for 35 min.

[0105] S2: Add 8 parts of silicon dioxide and stir at 1200 r / min for 50 min;

[0106] S3: Add 3 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 1 part of isomeric alcohol polyoxyethylene polyoxypropylene ether, 0.5 parts of diethylene glycol dibutyl ether, and 0.3 parts of polyethylene oxide alcohol. Stir at 1300 r / min for 30 min, and degas under vacuum to prepare the primer coating.

[0107] Preparation of topcoat layer 4:

[0108] S1: Mix 20 parts of bisphenol A acrylate, 20 parts of polyester acrylate, 20 parts of polyurethane acrylate, and 20 parts of diethylene glycol diacrylate. Heat the mixture in a mixing tank at 55°C and stir at 1100 r / min for 35 min.

[0109] S2: Add 30 parts of titanium dioxide and stir at 1300 r / min for 60 min;

[0110] S3: Add 4 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 1.5 parts of fatty alcohol polyoxypropylene ether, 1 part of triethylene glycol butyl ether, and 0.5 parts of silicone oil. Stir at 1300 r / min for 30 min, degas under vacuum, and the topcoat layer is prepared.

[0111] UV pad preparation:

[0112] S1: Clean the core layer 1 of the wood fiberboard, apply a 20μm thick layer of putty 2 coating with a rubber roller, smooth it with a textured roller, and then semi-cur it with 365nm UV light at a curing energy of 250mW / cm². 2 The curing time is 20 seconds, and matrix A is prepared.

[0113] S2: The primer layer 3, with a thickness of 15 μm, is applied to substrate A using a rubber roller, smoothed with an anilox roller, and then fully cured under 320 nm UV light at a curing energy of 180 mW / cm². 2 The curing time is 40 seconds to prepare matrix B;

[0114] S3: The topcoat layer 4, measuring 30 μm, is coated onto substrate B using a rubber roller, smoothed with an anilox roller, and then fully cured under 365 nm UV light at a curing energy of 300 mW / cm². 2 The curing time is 60s, and a UV pad 1 is prepared.

[0115] Example 2, Preparation of UV Pad 2

[0116] Putty layer 1 coating preparation steps:

[0117] S1: Mix 25 parts of bisphenol F epoxy resin, 2.5 parts of pentaerythritol tetra-3-mercaptopropionate and 2.5 parts of 1,1,3,3,-tetramethylguanidine, heat in a mixing tank at 100°C, stir at 1300 r / min for 40 min, and then cool to 60°C.

[0118] S2: Add 25 parts of epoxy-modified acrylate and 10 parts of ethoxyethoxyethyl acrylate, stir at 60℃ for 40 min, stirring speed 1500 r / min;

[0119] S3: Add 30 parts of titanium dioxide and stir at 1500 r / min for 60 min;

[0120] S4: Add 4 parts of 1-hydroxycyclohexyl phenyl ketone, 1 part of fatty alcohol polyoxypropylene ether, 1 part of diethylene glycol butyl ether, and 0.2 parts of silicone oil. Stir at 1300 r / min for 40 min, degas under vacuum, and the putty coating is ready.

[0121] Preparation steps for primer layer 3:

[0122] S1: Mix 40 parts of polyester acrylate, 20 parts of polyurethane acrylate, and 10 parts of pentaerythritol tetraacrylate ethoxylate. Heat the mixture in a mixing tank at 50°C and stir at 1100 r / min for 30 min.

[0123] S2: Add 10 parts of silicon dioxide and stir at 1200 r / min for 50 min;

[0124] S3: Add 2.5 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 1 part of fatty alcohol polyoxyethylene ether, 0.5 parts of diethylene glycol dibutyl ether, and 0.2 parts of polyethylene oxide alcohol. Stir at 1300 r / min for 30 min, and degas under vacuum to prepare the primer coating.

[0125] Preparation of topcoat layer 4:

[0126] S1: Mix 20 parts of bisphenol A acrylate, 20 parts of epoxy modified acrylate, 30 parts of polyurethane acrylate, and 25 parts of 1,6-hexanediol diacrylate. Heat the mixture in a mixing tank at 60°C and stir at 1100 r / min for 40 min.

[0127] S2: Add 30 parts of titanium dioxide and stir at 1300 r / min for 60 min;

[0128] S3: Add 4 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 1.5 parts of fatty alcohol polyoxypropylene ether, 1 part of triethylene glycol butyl ether, and 0.5 parts of silicone oil. Stir at 1300 r / min for 30 min, degas under vacuum, and the topcoat layer is prepared.

[0129] UV pad preparation:

[0130] S1: Clean the core layer 1 of the wood fiberboard, apply a 30μm thick layer of putty 2 coating with a rubber roller, smooth it with an anilox roller, and then semi-cur it with 365nm UV light at a curing energy of 300mW / cm². 2 The curing time is 25 seconds to prepare substrate A;

[0131] S2: The primer layer 3, with a thickness of 20 μm, is coated onto substrate A using a rubber roller, smoothed with an anilox roller, and then fully cured under 320 nm UV light at a curing energy of 200 mW / cm². 2 The curing time is 50 seconds to prepare matrix B;

[0132] S3: The topcoat layer 4, with a thickness of 20 μm, is coated onto substrate B using a rubber roller, smoothed with an anilox roller, and then fully cured under 365 nm UV light at a curing energy of 250 mW / cm². 2 The curing time is 50s, and UV pad 2 is prepared.

[0133] Example 3, Preparation of UV Pad 3

[0134] Putty layer 2 coating preparation steps:

[0135] S1: Mix 25 parts of alicyclic epoxy resin, 1.5 parts of diethanol glycol dimercaptoacetate and 2 parts of tetraphenylborone quaternary ammonium salt, heat in a mixing tank at 90°C, stir at 1300r / min for 40min, and then cool to 55°C.

[0136] S2: Add 30 parts of epoxy-modified acrylate and 20 parts of pentaerythritol tetraacrylate, stir at 55℃ for 40 min, stirring speed 1400 r / min;

[0137] S3: Add 40 parts of titanium dioxide and stir at 1500 r / min for 60 min;

[0138] S4: Add 4 parts of 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, 1 part of fatty alcohol polyoxyethylene ether, 1 part of diethylene glycol butyl ether, and 0.5 parts of silicone oil. Stir at 1500 r / min for 30 min, degas under vacuum, and the putty coating is ready.

[0139] Preparation steps for primer layer 3:

[0140] S1: Mix 30 parts of epoxy-modified acrylate, 30 parts of polyurethane acrylate and 15 parts of pentaerythritol tetraacrylate, heat in a mixing tank at 50°C, and stir at 1200 r / min for 35 min.

[0141] S2: Add 10 parts of glass microspheres and stir at 1200r / min for 60min;

[0142] S3: Add 3 parts of 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, 1.5 parts of fatty alcohol polyoxyethylene ether, 1 part of diethylene glycol dibutyl ether, and 0.5 parts of silicone oil. Stir at 1300 r / min for 30 min, and degas under vacuum to prepare the primer coating.

[0143] Preparation of topcoat layer 4:

[0144] S1: Mix 35 parts of polyurethane acrylate, 35 parts of polyester acrylate and 20 parts of dipropylene glycol diacrylate, heat in a mixing tank at 60°C, and stir at 1200 r / min for 35 min;

[0145] S2: Add 25 parts of titanium dioxide and stir at 1300 r / min for 50 min;

[0146] S3: Add 4 parts of 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, 0.5 parts of dispersant fatty alcohol polyoxypropylene ether, 0.3 parts of diethylene glycol butyl ether, and 0.3 parts of silicone oil. Stir at 1300 r / min for 30 min, degas under vacuum, and the topcoat layer is prepared.

[0147] UV pad preparation:

[0148] S1: Clean the core layer 1 of the wood fiberboard, apply a 25μm thick layer of putty 2 coating with a rubber roller, smooth it with a textured roller, and then semi-cur it with 365nm UV light at a curing energy of 280mW / cm². 2 The curing time is 25 seconds to prepare substrate A;

[0149] S2: The primer layer 3, with a thickness of 15 μm, is applied to substrate A using a rubber roller, smoothed with an anilox roller, and then fully cured under 320 nm UV light at a curing energy of 180 mW / cm². 2 The curing time is 45 seconds to prepare matrix B;

[0150] S3: The topcoat layer 4, with a thickness of 25 μm, is coated onto substrate B using a rubber roller, smoothed with an anilox roller, and then fully cured under 365 nm UV light at a curing energy of 230 mW / cm². 2 The curing time is 50 seconds, and a UV pad 3 is prepared.

[0151] Comparative Example 1: All active monomers in Example 1 were replaced with monofunctional acrylate-isobornyl acrylate.

[0152] Comparative Example 2: All active monomers in Example 1 were replaced with bifunctional acrylate-diethylene glycol diacrylate.

[0153] Comparative Example 3: All active monomers in Example 1 were replaced with polyfunctional acrylates - pentaerythritol tetraacrylate.

[0154] Comparative Example 4: The epoxy resin content in Example 1 was changed to 30 parts polyurethane acrylate, the photocuring delay agent content was changed to 15 parts isobornyl acrylate, and the polyfunctional thiol content and step S1 were removed.

[0155] Shrinkage stress was assessed on the filler-free primer coatings prepared in Examples 1-3 and Comparative Examples 1-3. Monofunctional, difunctional, and multifunctional active monomers were selected for shrinkage stress testing. Samples were prepared as 20mm diameter circles with a thickness of 100μm. Infrared-rheology spectrometry was used to monitor changes in shrinkage stress. Specific test details are detailed below. Figure 1 It can be seen that with the increase of functional groups, the shrinkage stress increases significantly. This shows that the coating prepared by the present invention can adjust the shrinkage stress and shrinkage rate by changing the functional group active monomer.

[0156] Then, the shrinkage rate of each layer in Examples 1-3 and Comparative Examples 1-3 (measured by laser confocal volume method) and the performance of the UV pad were tested. The specific data are shown in Table 1.

[0157] Table 1

[0158]

[0159] As can be seen from the data in Table 1, in Examples 1 to 3, by designing the shrinkage difference between the low-shrinkage putty layer coating and the high-shrinkage primer layer coating to be greater than 3%, the tensile shear strength of the prepared coating is significantly higher than that of Comparative Examples 1 to 4, which shows that the implementation effect of the present invention is obvious.

[0160] Meanwhile, due to the design of the low, high, and low stress difference structure of the putty layer / primer layer / topcoat layer, the surface warp is guaranteed. In contrast, although the multifunctional active monomers used in Comparative Example 3 can also achieve high hardness, the accumulation of internal stress leads to an increase in warp.

[0161] Comparative Example 4, due to the lack of a light-curing delayed design in the putty layer, could not achieve the effect of equivalent expansion of the putty layer, and its adhesion to the wood fiberboard core layer was about 40% weaker than that of Example 4.

[0162] The UV pad and manufacturing process prepared by this invention significantly improve the shortcomings of the prior art, providing a higher performance pad for PCB drilling while ensuring low cost and environmental protection requirements.

[0163] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A high-performance UV pad, characterized in that, The product comprises a wood fiberboard core layer and a surface coating. The surface coating consists of a putty layer, a primer layer, and a topcoat layer, arranged sequentially from the inside out. The putty layer contains a UV-curing delay agent, and the resin material of the putty layer is epoxy resin and epoxy-modified acrylate. The active monomers of the putty layer, primer layer, and topcoat layer are monofunctional, polyfunctional, and difunctional acrylates, respectively. The UV curing shrinkage rates of the putty layer, primer layer, and topcoat layer are 2–3%, 5–8%, and 3–5%, respectively.

2. The high-performance UV pad according to claim 1, characterized in that, The components of the putty layer, primer layer, and topcoat layer are as follows: Putty layer: 20-30 parts epoxy resin, 25-40 parts epoxy modified acrylate, 10-20 parts monofunctional active monomer, 2-4 parts photoinitiator, 1-3 parts photocuring retarder, 1-3 parts polyfunctional thiols, 20-50 parts filler and / or 0-5 parts other additives; Primer layer: 50-70 parts acrylate, 10-20 parts multifunctional active monomer, 2-4 parts photoinitiator, 5-10 parts filler and / or 0-5 parts other additives; Topcoat layer: 50-70 parts acrylate, 15-25 parts bifunctional active monomer, 2-4 parts photoinitiator, 20-30 parts filler and / or 0-5 parts other additives.

3. The high-performance UV pad according to claim 2, characterized in that, The ratio of the photoinitiator to the photocuring delayer in the putty layer is 1:0.5 to 0.

8.

4. The high-performance UV pad according to claim 2, characterized in that, The epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and alicyclic epoxy resin; the epoxy-modified acrylate is bisphenol A modified acrylate; and the acrylate is one or more of bisphenol A acrylate, polyester acrylate, and polyurethane acrylate.

5. The high-performance UV pad according to claim 2, characterized in that, The photoinitiator is one or more of methyl benzoylformate, 1-hydroxycyclohexyl benzophenone, 2,4,6-trimethylbenzoylbenzene-diphenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate; the photocuring retarder is one or more of carbamates, carboxylates, borates, quaternary ammonium salts, and benzylamidinates; and the polyfunctional thiol is one or more of pentaerythritol tetra-3-mercaptopropionate, trihydroxypropane (3-mercaptopropionate), di(3-mercaptopropionic acid) glycol ester, trimethylolpropane tris(2-mercaptoacetic acid), dimercaptoacetic acid diethanolate, and ethoxytrimethylolpropane tris(3-mercaptopropionate).

6. The high-performance UV pad according to claim 2, characterized in that, The other additives are one or more of dispersants, leveling agents, defoamers, and matting agents. The dispersant is a polymeric dispersant, the leveling agent is an organosilicon leveling agent, the defoamer is an organosilicon defoamer or a polyether defoamer, the matting agent is one or more of organically modified fumed silica, and the filler is one or more of silica, glass microspheres, titanium dioxide, talc, and aluminum hydroxide.

7. The high-performance UV pad according to claim 2, characterized in that, The monofunctional active monomer is one or more of β-hydroxyethyl methacrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, and tetrahydrofurfuryl acrylate; the difunctional active monomer is one or more of 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, and tripropylene glycol diacrylate; and the polyfunctional active monomer is one or more of pentaerythritol tetraacrylate, pentaerythritol tetraacrylate ethoxylate, di-trimethylolpropane tetraacrylate, and dipentaerythritol pentaacrylate.

8. A process for preparing the high-performance UV pad according to any one of claims 1 to 7, characterized in that, Prepared by the following steps: S1: The surface of the wood fiberboard core layer is coated with a 20-30 μm thick putty layer, and then semi-cured under 320-365 nm UV light for 10-30 seconds to prepare substrate A, with a curing energy of 250-300 mW / cm². 2 ; S2: A primer layer of 10–20 μm is coated onto substrate A, and substrate B is prepared by complete curing under 320–365 nm UV light for 40–60 seconds, with a curing energy of 150–200 mW / cm². 2 ; S3: The substrate B is coated with a 20-30 μm thick topcoat layer, and then completely cured under 320-365 nm UV light for 40-60 seconds to prepare the high-performance UV pad. The curing energy is 200-300 mW / cm². 2 .

9. The manufacturing process of the high-performance UV pad according to claim 8, characterized in that, The curing degree of the putty layer on the substrate A is 40-60%.

10. The manufacturing process of the high-performance UV pad according to claim 8, characterized in that, The 320-365nm ultraviolet transmittance of the primer layer on substrate B is 30-50%.

Images