A photocurable polyurethane acrylate, a preparation method and application thereof

Abstract

The application discloses a photocurable polyurethane acrylate and a preparation method and application thereof, and belongs to the technical field of photosensitive resins. The photocurable polyurethane acrylate is shown in a chemical formula as shown in formula 1. The photocurable polyurethane acrylate has six olefinic functionalities and contains urethane groups, can improve the light curing efficiency while improving the hole covering ability of the photosensitive dry film, ensures that the dry film has sufficient toughness and strength to resist the impact of the developing solution without breaking the hole when the dry film is impacted by the developing solution, and has excellent photosensitivity, adhesion and anti-flowing ability.

Description

Technical Field

[0001] This invention belongs to the field of photosensitive resin technology, specifically relating to a photocurable polyurethane acrylate, its preparation method, and its application. Background Technology

[0002] Photosensitive resin compositions are widely used as key pattern transfer materials in the manufacturing of printed circuit boards (PCBs), lead frames (LFs), and semiconductor packaging (IC) substrates. The photosensitive resin composition is typically coated onto the surface of a PET support film, and after drying, a protective layer, such as a polyethylene film (PE) protective layer, is tightly bonded to its surface; this protective layer is also known as a photosensitive dry film or dry film resist. The pattern transfer process involves first bonding the dry film resist onto a copper substrate, then covering the dry film resist with a mask bearing a specific pattern for exposure. Next, a weakly alkaline aqueous solution is used as a developer to remove unexposed areas, followed by etching or electroplating to form the pattern. Finally, a stripping solution is used to remove the cured dry film, thus achieving pattern transfer.

[0003] As electronic devices become increasingly miniaturized and denser, the requirements for circuit precision are constantly rising. To meet the demands of fine circuit manufacturing, photosensitive resin compositions need to possess higher hole-covering capabilities and adhesion. Photosensitive resins typically consist of alkali-soluble resins, photocurable monomers, photoinitiators, and additives. Among these, photocurable monomers have a significant impact on the hole-covering capabilities and adhesion of photosensitive resins. Polyurethane acrylate photocurable monomers are widely used in photosensitive dry films because they can introduce strongly polar urethane groups into their molecular structure. Urethane groups can form strong hydrogen bonds, effectively improving the resin's cohesiveness, adhesion, and hole-covering performance. Currently, difunctional polyurethane acrylates are mainly used in actual production, which often suffer from low photosensitivity and low crosslinking density. To further improve the curing crosslinking density to achieve higher performance, the industry commonly adopts methods to increase the functionality of PUA. However, traditional synthesis methods rely on high-functionality monomers, leading to a sharp increase in viscosity during the reaction process, posing a risk of gelation, making large-scale production difficult, and requiring remelting processing of the product, resulting in poor economic efficiency. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a photocurable polyurethane acrylate, its preparation method, and its application.

[0005] In a first aspect, the present invention provides a photocurable polyurethane acrylate, comprising at least one structure as shown in Formula I:

[0006]

[0007] Where: 'R is hydrogen or methyl; R is as shown in Formula II:

[0008]

[0009] In Formula II The term indicates the site connected to the main structural formula I. R1 is one of the following: a C2-C4 straight-chain alkyl group, a C2-C8 straight-chain ether alkane, or a C4-C12 straight-chain ester alkane; R2 is one of the following: an aryl group, a substituted aryl group, a C5-C8 straight-chain alkyl group, a cycloalkyl group, or a substituted cycloalkyl group; R3 is one of the following: a C4-C8 alkyl group, a C4-C8 substituted alkyl group, a phenyl group, or a substituted phenyl group; R4 is a C2-C4 straight-chain alkyl group; R5 is hydrogen or methyl; and n ranges from 1 to 80.

[0010] Preferably, formula II is one of formulas 1 to 6:

[0011] .

[0012] Secondly, the present invention provides a method for preparing photocurable polyurethane acrylate, the reaction route of which is as follows:

[0013] ;

[0014] Includes the following steps:

[0015] Step S1: After mixing compound 1 and compound 2, a reaction solution is obtained and heated to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain compound 3, wherein the molar ratio of compound 1 to compound 2 is 1:(1.8~2.2).

[0016] Step S2: Dissolve compound 3, compound 4 and catalyst in solvent and heat to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain a reaction solution containing compound 5, wherein the molar ratio of compound 3 to compound 4 is 1:(1.8~2.2).

[0017] Step S3: After dissolving compound 6 in a solvent, add it to the reaction solution containing compound 5 and heat the reaction until the mass percentage of -NCO groups in the reaction solution is 0, to obtain a reaction solution containing compound 7, wherein the molar ratio of compound 5 to compound 6 is 1:(1.8~2.2).

[0018] Step S4: After dissolving compound 8 in a solvent, add it to the reaction solution containing compound 7 and react until the acid value in the reaction solution is 0. Then, add the solution dropwise to a poor solvent to precipitate the product. After filtration, washing and drying, obtain a photocurable polyurethane acrylate, wherein the molar ratio of compound 7 to compound 8 is 1:(2.7~3.3).

[0019] Preferably, in steps S1, S2 and S3, the heating reaction temperature is 50~100℃ and the heating reaction time is 1~3h.

[0020] Preferably, in step S1, compound 1 is selected from one of poly(ethylene adipate), polyethylene adipate, polycarbonate diol, polycaprolactone, polyethylene glycol, polypropylene glycol, and polybutanediol; more preferably, it is poly(ethylene adipate).

[0021] Preferably, in step S1, the number average molecular weight of compound 1 is 400 to 4000, and more preferably 1000.

[0022] Preferably, in step S1, compound 2 is one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4-diisocyanate dicyclohexylmethane, cyclohexane-1,4-diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, 4,4'-diisocyanate diphenylmethane, 2,4'-diisocyanate diphenylmethane, 2,2'-diisocyanate diphenylmethane, and naphthalene diisocyanate, and more preferably hexamethylene diisocyanate.

[0023] Preferably, in step S1, the molar ratio of compound 1 to compound 2 is 1:2.

[0024] Preferably, in step S2, the catalyst is DBTDL (dibutyltin dilaurate), and the amount of catalyst added is 0.01~0.1 wt% of the mass of compound 3.

[0025] Preferably, in step S2, compound 4 is one of 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, and 3,4-dihydroxybenzoic acid, and more preferably 2,2-dimethylolpropionic acid.

[0026] Preferably, in step S2, the molar ratio of compound 3 to compound 4 is 1:2.

[0027] Preferably, in step S3, compound 6 is one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate, and more preferably hydroxyethyl acrylate.

[0028] Preferably, in step S3, the molar ratio of compound 5 to compound 6 is 1:2.

[0029] Preferably, in step S4, compound 8 is one or more of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] and trimethylolpropane-tris(3-acridinyl)propionate, and more preferably trimethylolpropane-tris[3-(2-methylacridinyl)propionate].

[0030] Preferably, in step S4, the reaction temperature is 0~100℃ and the reaction time is 10~120min; more preferably, the heating reaction temperature is 40℃ and the heating reaction time is 30min.

[0031] Preferably, in step S4, the molar ratio of compound 7 to compound 8 is 1:3.

[0032] Preferably, in steps S2, S3, and S4, the solvent is one or more of acetone, butanone, cyclohexanone, ethyl acetate, toluene, xylene, N'N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, and dipropylene glycol monomethyl ether.

[0033] Preferably, in step S4, the undesirable solvent is n-hexane.

[0034] Thirdly, the present invention provides a photosensitive resin composition comprising the aforementioned photocurable polyurethane acrylate.

[0035] Preferably, the photosensitive resin composition further includes an alkali-soluble resin, a photoinitiator, and a photosensitizer.

[0036] Preferably, the photosensitive resin composition comprises, by weight fraction: 50-65 parts of alkali-soluble resin; 35-50 parts of photocurable polyurethane acrylate; 2-5 parts of photoinitiator; and 0.1-1 parts of photosensitizer.

[0037] Preferably, the alkali-soluble resin is obtained by polymerization of one or more monomers selected from (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, benzyl (meth)acrylate derivatives, phenyl (meth)acrylate, styrene, and styrene derivatives; more preferably, the alkali-soluble resin is obtained by polymerization of one or more monomers selected from (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, and styrene.

[0038] Preferably, during the polymerization process, monomers containing aromatic groups account for 50-70% of the total monomer mass.

[0039] Preferably, the alkali-soluble resin has a weight-average molecular weight of 20,000 to 60,000, an acid value of 160 to 220 mg KOH / g, and a molecular weight distribution of 1.0 to 3.0.

[0040] Preferably, the photoinitiator is a 2,4,5-triarylimidazolium dimer, more preferably one or more of the following: 2-(2-chlorophenyl)-4,5-diphenylimidazolium dimer, 2-(2-chlorophenyl)-4,5-di(methoxyphenyl)imidazolium dimer, 2-(2-fluorophenyl)-4,5-diphenylimidazolium dimer, 2-(2-methoxyphenyl)-4,5-diphenylimidazolium dimer, 2-(4-methoxyphenyl)-4,5-diphenylimidazolium dimer, and 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-diimidazole.

[0041] Preferably, the photosensitizer is one or more of 9,10-dibutoxyanthracene (DBA), 9,10-diphenylanthracene (DPHA), and 9,10-diacetoxyanthracene (DAcOA).

[0042] Preferably, the photosensitive resin composition further includes additives, which are one or more of dyes, photodevelopers, plasticizers, adhesion promoters, polymerization inhibitors, defoamers, and coating aids; the additives are present in parts by weight of 0.5 to 5.0 parts.

[0043] Preferably, the photosensitive resin composition further includes a solvent, which is one or more of acetone, toluene, and methanol; the solvent is in the form of 15 to 25 parts by weight.

[0044] Fourthly, the present invention also provides a photosensitive dry film comprising, from bottom to top, a PET layer, a photosensitive etchant layer and a PE layer, wherein the photosensitive etchant layer is prepared from the aforementioned photosensitive resin composition.

[0045] Fifthly, the present invention also provides an application of photosensitive dry film in printed circuit boards, lead frames or semiconductor packaging substrates.

[0046] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0047] The photocurable polyurethane acrylate in this invention has six olefin functional groups and contains urethane groups. It can improve the pore-covering ability of the photosensitive dry film, improve the photocuring efficiency, ensure that the dry film has sufficient toughness and strength to withstand the impact of the developer without breaking the pores, and also has excellent photosensitivity, adhesion and anti-drip ability. Attached Figure Description

[0048] Figure 1 The infrared spectra of intermediate product 1, intermediate product 2, intermediate product 3 and photocurable polyurethane acrylate D1 shown in Example 1 of the present invention are shown.

[0049] Figure 2 The infrared spectra of intermediate product 1, intermediate product 2, intermediate product 3 and photocurable polyurethane acrylate D2 shown in Example 2 of the present invention are shown.

[0050] Figure 3 The infrared spectra of intermediate product 1, intermediate product 2, intermediate product 3 and photocurable polyurethane acrylate D3 shown in Example 3 of the present invention are shown. Detailed Implementation

[0051] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0053] In a first aspect, the present invention provides a photocurable polyurethane acrylate, the chemical formula of which is shown in Formula 1:

[0054]

[0055] Where: 'R is hydrogen or methyl; R is as shown in Formula II:

[0056]

[0057] In Formula II The term indicates the site connected to the main structural formula I. R1 is one of the following: a C2-C4 straight-chain alkyl group, a C2-C8 straight-chain ether alkane, or a C4-C12 straight-chain ester alkane; R2 is one of the following: an aryl group, a substituted aryl group, a C5-C8 straight-chain alkyl group, a cycloalkyl group, or a substituted cycloalkyl group; R3 is one of the following: a C4-C8 alkyl group, a C4-C8 substituted alkyl group, a phenyl group, or a substituted phenyl group; R4 is a C2-C4 straight-chain alkyl group; R5 is hydrogen or methyl; and n ranges from 1 to 80.

[0058] To avoid directly using high-functionality raw materials, this invention adopts a more sophisticated "post-functionalization" method to construct high-functionality structures in situ while maintaining good processability of the system, thereby achieving the synthesis of high-performance PUA.

[0059] The photopolymer monomers of this invention, containing six olefinic functional groups, can better perform photocuring and improve the photocuring efficiency of the photosensitive resin combination. When the photopolymer monomers of this invention are used to prepare photosensitive dry films with photosensitive resins, the dry films have better toughness and strength, and can withstand the impact of the developer without breaking the pores, thus effectively improving the pore-covering performance of the photosensitive dry films.

[0060] The photopolymer monomers in this invention contain a high number of NH bonds synthesized by the reaction of aziridine crosslinking agent and carboxyl groups, and the polyurethane acrylates also contain a high number of amino and ester bonds. These can interact with other components in the photosensitive resin composition to form hydrogen bonds, improving the anti-drip properties of the photosensitive dry film at room temperature and lower temperatures, which is beneficial for the storage of the photosensitive dry film. During subsequent use, the hydrogen bonds are broken by high temperature, which increases the fluidity of the photosensitive dry film and facilitates the adhesion of the photosensitive dry film to the substrate. The aziridine-mediated crosslinking reaction realizes the covalent connection of the three molecular chains, resulting in an increase in the number of vinyl functional groups from the initial two to six, which is beneficial for improving the photocuring efficiency. In addition, the photopolymer monomers in this invention contain polyester or polyether diols and urethane groups, which can effectively improve the mechanical strength and toughness of the photosensitive dry film.

[0061] Preferably, formula II is one of formulas 1 to 6:

[0062] .

[0063] Secondly, the present invention provides a method for preparing photocurable polyurethane acrylate, the reaction route of which is as follows:

[0064] ;

[0065] Includes the following steps:

[0066] Step S1: After mixing compound 1 and compound 2, a reaction solution is obtained and heated to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain compound 3, wherein the molar ratio of compound 1 to compound 2 is 1:(1.8~2.2).

[0067] Step S2: Dissolve compound 3, compound 4 and catalyst in solvent and heat to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain a reaction solution containing compound 5, wherein the molar ratio of compound 3 to compound 4 is 1:(1.8~2.2).

[0068] Step S3: After dissolving compound 6 in a solvent, add it to the reaction solution containing compound 5 and heat the reaction until the mass percentage of -NCO groups in the reaction solution is 0, to obtain a reaction solution containing compound 7, wherein the molar ratio of compound 5 to compound 6 is 1:(1.8~2.2).

[0069] Step S4: After dissolving compound 8 in a solvent, add it to the reaction solution containing compound 7 and react until the acid value in the reaction solution is 0. Then, add the solution dropwise to a poor solvent to precipitate the product. After filtration, washing and drying, obtain a photocurable polyurethane acrylate, wherein the molar ratio of compound 7 to compound 8 is 1:(2.7~3.3).

[0070] The preparation method of the present invention is simple, the reaction conditions are not harsh, and it is easy to realize industrial production.

[0071] Preferably, in steps S1, S2 and S3, the heating reaction temperature is 50~100℃ and the heating reaction time is 1~3h.

[0072] Preferably, in step S1, compound 1 is selected from one of poly(ethylene adipate), polyethylene adipate, polycarbonate diol, polycaprolactone, polyethylene glycol, polypropylene glycol, and polybutanediol; more preferably, it is poly(ethylene adipate).

[0073] Preferably, in step S1, the number-average molecular weight of compound 1 is 400-4000, more preferably 1000.

[0074] Preferably, in step S1, compound 2 is one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4-diisocyanate dicyclohexylmethane, cyclohexane-1,4-diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, 4,4'-diisocyanate diphenylmethane, 2,4'-diisocyanate diphenylmethane, 2,2'-diisocyanate diphenylmethane, and naphthalene diisocyanate, and more preferably hexamethylene diisocyanate.

[0075] Preferably, in step S1, the molar ratio of compound 1 to compound 2 is 1:2.

[0076] Preferably, in step S2, the catalyst is DBTDL, and the amount of catalyst added is 0.01~0.1 wt% of the mass of compound 3.

[0077] Preferably, in step S2, compound 4 is one of 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, and 3,4-dihydroxybenzoic acid, and more preferably 2,2-dimethylolpropionic acid.

[0078] Preferably, in step S2, the molar ratio of compound 3 to compound 4 is 1:2.

[0079] Preferably, in step S3, compound 6 is one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate, and more preferably hydroxyethyl acrylate.

[0080] Preferably, in step S3, the molar ratio of compound 5 to compound 6 is 1:2.

[0081] Preferably, in step S4, compound 8 is one of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] and trimethylolpropane-tris(3-acridinyl)propionate, and more preferably trimethylolpropane-tris[3-(2-methylacridinyl)propionate.

[0082] Preferably, in step S4, the reaction temperature is 0~100℃ and the reaction time is 10~120min; more preferably, the heating reaction temperature is 40℃ and the heating reaction time is 30min.

[0083] Preferably, in step S4, the molar ratio of compound 7 to compound 8 is 1:3.

[0084] Preferably, in steps S2, S3 and S4, the solvent is one or more of acetone, butanone, cyclohexanone, ethyl acetate, toluene, xylene, N'N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, and dipropylene glycol monomethyl ether.

[0085] Preferably, in step S4, the undesirable solvent is n-hexane.

[0086] Thirdly, the present invention provides a photosensitive resin composition comprising the aforementioned photocurable polyurethane acrylate.

[0087] Preferably, the photosensitive resin composition further includes an alkali-soluble resin, a photoinitiator, and a photosensitizer.

[0088] Preferably, the photosensitive resin composition comprises, by weight parts: 50-65 parts of alkali-soluble resin; 35-50 parts of photocurable polyurethane acrylate; 2-5 parts of photoinitiator; and 0.1-1 parts of photosensitizer.

[0089] Preferably, the alkali-soluble resin is obtained by polymerization of one or more monomers selected from (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, benzyl (meth)acrylate derivatives, phenyl (meth)acrylate, styrene, and styrene derivatives; more preferably, the alkali-soluble resin is obtained by polymerization of one or more monomers selected from (meth)acrylic acid, alkyl (meth)acrylate, benzyl (meth)acrylate, and styrene.

[0090] Preferably, during the polymerization process, monomers containing aromatic groups account for 50-70% of the total monomer mass.

[0091] Preferably, the alkali-soluble resin has a weight-average molecular weight of 20,000 to 60,000, an acid value of 160 to 220 mg KOH / g, and a molecular weight distribution of 1.0 to 3.0.

[0092] Preferably, the photoinitiator is a 2,4,5-triarylimidazolium dimer, more preferably one or more of the following: 2-(2-chlorophenyl)-4,5-diphenylimidazolium dimer, 2-(2-chlorophenyl)-4,5-di(methoxyphenyl)imidazolium dimer, 2-(2-fluorophenyl)-4,5-diphenylimidazolium dimer, 2-(2-methoxyphenyl)-4,5-diphenylimidazolium dimer, 2-(4-methoxyphenyl)-4,5-diphenylimidazolium dimer, and 2,2',4-tris(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)-4',5'-diphenyl-1,1'-diimidazole.

[0093] Preferably, the photosensitizer is one or more of 9,10-dibutoxyanthracene (DBA), 9,10-diphenylanthracene (DPHA), and 9,10-diacetoxyanthracene (DAcOA).

[0094] Preferably, the photosensitive resin composition further includes additives, which are one or more of dyes, photodevelopers, plasticizers, adhesion promoters, polymerization inhibitors, defoamers, and coating aids; the additives are present in parts by weight of 0.5 to 5.0 parts.

[0095] Preferably, the photosensitive resin composition further includes a solvent, which is one or more of acetone, toluene, and methanol; the solvent is in the form of 15 to 25 parts by weight.

[0096] Fourthly, the present invention also provides a photosensitive dry film comprising, from bottom to top, a PET layer, a photosensitive etchant layer and a PE layer, wherein the photosensitive etchant layer is prepared from the aforementioned photosensitive resin composition.

[0097] Fifthly, the present invention also provides an application of photosensitive dry film in printed circuit boards, lead frames or semiconductor packaging substrates.

[0098] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0099] Example 1

[0100] The preparation method of the photocurable polyurethane acrylate D1 in this embodiment includes the following steps:

[0101] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 34.0g of hexamethylene diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0102] S2: Dissolve 6.7g of 2,2-dihydroxymethylpropionic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, and obtain a solution containing intermediate product 2.

[0103] S3: Dissolve 11.6g of hydroxyethyl acrylate in butanone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0104] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in butanone and add it to a reaction flask containing intermediate product 3. Heat to 40℃ and crosslink for 30 min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D1.

[0105] The specific synthesis route is as follows:

[0106] .

[0107] Infrared spectroscopy was performed on intermediate products 1, 2, and 3 prepared in this embodiment, as well as the photocurable polyurethane acrylate D1. The results are shown below. Figure 1 It can be seen that the curve for intermediate product 1 has a peak at 1530 cm⁻¹. -1 The peak at 776 cm⁻¹ is the NH bending vibration peak. -1The NH out-of-plane bending vibration at 2254 cm⁻¹ indicates the successful introduction of the urethane group. -1 The characteristic peak of the -NCO group indicates the presence of the -NCO group and the ability to continue the reaction, thus confirming the synthesis of intermediate 1; in the curve of intermediate 2, the peak at 1722 cm⁻¹... -1 The stretching vibration of the carbonyl group is significantly broadened, and the characteristic peak of the -NCO group decreases significantly, indicating the successful introduction of the carboxyl group and proving the synthesis of intermediate product 2. In the curve of intermediate product 3, the absorption peak of the -NCO group completely disappears, indicating that -NCO has been completely reacted, proving the synthesis of intermediate product 3. The 920 cm⁻¹ peak of the photocurable polyurethane acrylate D1 is... -1 The ring stretching vibration of the aziridine ring and 1230 cm -1 The disappearance of the CN stretching vibration of the aziridine ring indicates the reaction of the aziridine group, proving the synthesis of photocurable polyurethane acrylate D1.

[0108] Example 2

[0109] The preparation method of the photocurable polyurethane acrylate D2 in this embodiment includes the following steps:

[0110] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 34.8g of toluene-2,4-diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0111] S2: Dissolve 6.7g of 2,2-dihydroxymethylpropionic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, and obtain a solution containing intermediate product 2.

[0112] S3: Dissolve 11.6g of hydroxyethyl acrylate in butanone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0113] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in butanone and add it to a reaction flask containing intermediate product 3. Heat to 40℃ and crosslink for 30min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D2.

[0114] The specific synthesis route is as follows:

[0115] .

[0116] Infrared spectroscopy was performed on intermediate products 1, 2, and 3 prepared in this embodiment, as well as the photocurable polyurethane acrylate D2. The results are shown below. Figure 2 It can be seen that: in the curve of intermediate product 1, 1534cm -1 The peak at 766 cm⁻¹ is the NH bending vibration peak. -1 The out-of-plane bending vibration at 2255 cm⁻¹ indicates the successful introduction of the urethane group. -1 The characteristic peak of the -NCO group indicates the presence of the -NCO group and the ability to continue the reaction, thus confirming the synthesis of intermediate 1; in the curve of intermediate 2, the peak at 1728 cm⁻¹... -1 The stretching vibration of the carbonyl group is significantly broadened, and the characteristic peak of the -NCO group decreases significantly, indicating the successful introduction of the carboxyl group and proving the synthesis of intermediate product 2. In the curve of intermediate product 3, the absorption peak of the -NCO group completely disappears, indicating that -NCO has been completely reacted, proving the synthesis of intermediate product 3. The 920 cm⁻¹ peak of the photocurable polyurethane acrylate D2 is... -1 The ring stretching vibration of the aziridine ring and 1230 cm -1 The disappearance of the CN stretching vibration of the aziridine ring indicates the reaction of the aziridine group, proving the synthesis of photocurable polyurethane acrylate D2.

[0117] Example 3

[0118] The preparation method of the photocurable polyurethane acrylate D3 in this embodiment includes the following steps:

[0119] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 44.5g of isophorone diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0120] S2: Dissolve 6.7g of 2,2-dihydroxymethylpropionic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, and obtain a solution containing intermediate product 2.

[0121] S3: Dissolve 11.6g of hydroxyethyl acrylate in butanone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0122] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in butanone and add it to a reaction flask containing intermediate product 3. Heat to 40℃ and crosslink for 30min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D3.

[0123] The specific synthesis route is as follows:

[0124] .

[0125] Infrared spectroscopy was performed on intermediate products 1, 2, and 3 prepared in this embodiment, as well as the photocurable polyurethane acrylate D3. The results are shown below. Figure 3 It can be seen that: in the curve of intermediate product 1, 1527cm -1 The peak at 774 cm⁻¹ is the NH bending vibration peak. -1 The out-of-plane bending vibration at 2255 cm⁻¹ indicates the successful introduction of the urethane group. -1 The characteristic peak of the -NCO group indicates the presence of the -NCO group and the ability to continue the reaction, thus confirming the synthesis of intermediate 1; in the curve of intermediate 2, the peak at 1726 cm⁻¹... -1 The stretching vibration of the carbonyl group is significantly broadened, and the characteristic peak of the -NCO group decreases significantly, indicating the successful introduction of the carboxyl group and proving the synthesis of intermediate product 2. In the curve of intermediate product 3, the absorption peak of the -NCO group completely disappears, indicating that -NCO has been completely reacted, proving the synthesis of intermediate product 3. The 920 cm⁻¹ peak of the photocurable polyurethane acrylate D3 is... -1 The ring stretching vibration of the aziridine ring and 1230 cm -1 The disappearance of the CN stretching vibration of the aziridine ring indicates the reaction of the aziridine group, proving the synthesis of photocurable polyurethane acrylate D3.

[0126] Example 4

[0127] The preparation method of the photocurable polyurethane acrylate D4 in this embodiment includes the following steps:

[0128] S1: Mix 100.0g of polyethylene glycol-1000 and 34.0g of hexamethylene diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0129] S2: Dissolve 7.7g of 3,5-dihydroxybenzoic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain a solution containing intermediate product 2.

[0130] S3: Dissolve 11.6g of hydroxyethyl acrylate in butanone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0131] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in butanone and add it to a reaction flask containing intermediate product 3. Heat to 40℃ and crosslink for 30 min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D4.

[0132] The specific synthesis route is as follows:

[0133] .

[0134] Example 5

[0135] The preparation method of the photocurable polyurethane acrylate D5 in this embodiment includes the following steps:

[0136] S1: Mix 100.0g of polyethylene glycol-1000 and 34.0g of hexamethylene diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0137] S2: Dissolve 6.7g of 2,2-dihydroxymethylpropionic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, and obtain a solution containing intermediate product 2.

[0138] S3: Dissolve 13.0g of hydroxyethyl methacrylate in butanone solvent, add it to a reaction flask containing intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0139] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in butanone and add it to a reaction flask containing intermediate product 3. Heat to 40℃ and crosslink for 30 min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D5.

[0140] The specific synthesis route is as follows:

[0141] .

[0142] Example 6

[0143] The preparation method of photocurable polyurethane acrylate D6 in this embodiment includes the following steps:

[0144] S1: Mix 100.0g of polyethylene glycol-1000 and 34.0g of hexamethylene diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0145] S2: Dissolve 6.7g of 2,2-dihydroxymethylpropionic acid and 0.05g of catalyst DBTDL in butanone, and then add it to the reaction flask containing intermediate product 1. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, and obtain a solution containing intermediate product 2.

[0146] S3: Dissolve 11.6g of hydroxyethyl acrylate in butanone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 80℃ and react for 2h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0147] S4: Dissolve 7.1g of aziridine crosslinking agent [trimethylolpropane-tris[3-(aziridine)propionate] in butanone, add it to a reaction flask containing intermediate product 3, heat to 40℃ and crosslink for 30 min. When the acid value is basically 0 by acid-base titration, add it dropwise to n-hexane to precipitate. After filtration, collect the solid, wash it with n-hexane, and vacuum dry it at 40℃ to obtain photocurable polyurethane acrylate D6.

[0148] The specific synthesis route is as follows:

[0149] .

[0150] Example 7

[0151] The preparation method of the photocurable polyurethane acrylate D7 in this embodiment includes the following steps:

[0152] S1: Mix 40.0g of polyethylene glycol-400 and 55.0g of 4,4-diisocyanate dicyclohexylmethane to obtain a reaction solution. Heat the reaction solution to 60℃ and react for 3h until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0153] S2: Dissolve 7.7g of 2,6-dihydroxybenzoic acid and 0.05g of catalyst DBTDL in toluene, then add them to the reaction flask containing intermediate product 1. Heat the reaction solution to 60℃ and react for 3 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, thus obtaining a solution containing intermediate product 2.

[0154] S3: Dissolve 13.0g of hydroxyethyl methacrylate in toluene solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 60℃ and react for 3h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0155] S4: Dissolve 7.1 g of aziridine crosslinking agent [trimethylolpropane-tris[3-(aziridine)propionate] in toluene, add it to a reaction flask containing the solution of intermediate 3, and heat to 20°C. ℃ After the crosslinking reaction was carried out for 40 minutes, the acid value was determined to be approximately 0 by acid-base titration. Then, hexane was added dropwise to the reaction solution to cause precipitation. The solid was collected after filtration, washed with hexane, and then vacuum dried at 40°C to obtain photocurable polyurethane acrylate D7.

[0156] The specific synthesis route is as follows:

[0157] .

[0158] Example 8

[0159] The preparation method of photocurable polyurethane acrylate D8 in this embodiment includes the following steps:

[0160] S1: Mix 150.0g of polyethylene glycol-1500 and 55.0g of 4,4-diisocyanate dicyclohexylmethane to obtain a reaction solution. Heat the reaction solution to 90℃ and react for 1 hour until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0161] S2: Dissolve 7.7g of 2,6-dihydroxybenzoic acid and 0.05g of catalyst DBTDL in acetone, then add them to the reaction flask containing intermediate product 1. Heat the reaction solution to 90℃ and react for 1 hour until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, thus obtaining a solution containing intermediate product 2.

[0162] S3: Dissolve 13.0g of hydroxyethyl methacrylate in acetone solvent, add it to the reaction flask containing the solution of intermediate product 2, heat to 90℃ and react for 1h. When the mass percentage of -NCO groups in the reaction solution is basically 0, a solution containing intermediate product 3 is obtained.

[0163] S4: Dissolve 7.8g of aziridine crosslinking agent [trimethylolpropane-tris[3-(2-methylaziridine)propionate] in acetone, add it to a reaction flask containing intermediate product 3, heat to 80℃ and crosslink for 15min. When the acid value is basically 0 by acid-base titration, add the reaction solution dropwise to n-hexane to precipitate. After filtration, collect the solid, wash with n-hexane, and vacuum dry at 40℃ to obtain photocurable polyurethane acrylate D8.

[0164] .

[0165] The trends in the infrared spectra of intermediate products 1, 2, 3 and photocurable polyurethane acrylate in Examples 4-8 are basically similar to those in Examples 1-3, and will not be elaborated here.

[0166] Comparative Example 1

[0167] The preparation method of the difunctional polyurethane acrylate D9 in this comparative example includes the following steps:

[0168] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 34.8g of toluene-2,4-diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0169] S2: 23.2g of hydroxyethyl acrylate and 0.05g of catalyst DBTDL were added to the reaction flask of intermediate product 1. The reaction solution was heated to 80℃ and reacted for 2h. When the mass percentage of -NCO groups in the reaction solution was basically 0, the reaction solution was added dropwise to n-hexane to precipitate. The solid was collected after filtration, washed with n-hexane, and dried under vacuum at 40℃ to obtain difunctional polyurethane acrylate D9.

[0170] Comparative Example 2

[0171] The preparation method of the difunctional polyurethane acrylate D10 in this comparative example includes the following steps:

[0172] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 34.0g of hexamethylene diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0173] S2: 23.2g of hydroxyethyl acrylate and 0.05g of catalyst DBTDL were added to the reaction flask of intermediate product 1. The reaction solution was heated to 80℃ and reacted for 2h. When the mass percentage of -NCO groups in the reaction solution was basically 0, the reaction solution was added dropwise to n-hexane to precipitate. The solid was collected after filtration, washed with n-hexane, and dried under vacuum at 40℃ to obtain difunctional polyurethane acrylate D10.

[0174] Comparative Example 3

[0175] The preparation method of the difunctional polyurethane acrylate D11 in this comparative example includes the following steps:

[0176] S1: Mix 100.0g of poly(ethylene adipate)-1000 and 44.5g of isophorone diisocyanate to obtain a reaction solution. Heat the reaction solution to 80℃ and react for 2 hours until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain intermediate product 1.

[0177] S2: 23.2g of hydroxyethyl acrylate and 0.05g of catalyst DBTDL were added to the reaction flask of intermediate product 1. The reaction solution was heated to 80℃ and reacted for 2h. When the mass percentage of -NCO groups in the reaction solution was basically 0, the reaction solution was added dropwise to n-hexane to precipitate. The solid was collected after filtration, washed with n-hexane, and dried under vacuum at 40℃ to obtain difunctional polyurethane acrylate D11.

[0178] Examples 9-16 and Comparative Examples 4-6

[0179] The compositions of the photosensitive resin compositions of Examples 9-16 and Comparative Examples 4-6 are shown in Table 1.

[0180]

[0181] Alkali-soluble resin A: acrylate copolymer, solution polymerization, polymerized by mass ratio of methacrylic acid monomer / butyl methacrylate monomer / benzyl methacrylate monomer = 25 / 10 / 65; solvent is acetone, solid content is 46%, weight average molecular weight is 40000, dispersity is 2.1, and acid value is 163 mgKOH / g.

[0182] Photoinitiator B is 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-diimidazole (BCIM).

[0183] Photosensitizer C is 9,10-dibutoxyanthracene

[0184] Photopolymerizable monomer D:

[0185] D1 is the photocurable polyurethane acrylate from Example 1.

[0186] D2 is the photocurable polyurethane acrylate from Example 2.

[0187] D3 is the photocurable polyurethane acrylate from Example 3.

[0188] D4 is the photocurable polyurethane acrylate from Example 4.

[0189] D5 is the photocurable polyurethane acrylate from Example 5.

[0190] D6 is the photocurable polyurethane acrylate from Example 6.

[0191] D7 is the photocurable polyurethane acrylate from Example 7.

[0192] D8 is the photocurable polyurethane acrylate from Example 8.

[0193] D9 is a difunctional polyurethane acrylate from Comparative Example 1.

[0194] D10 is a difunctional polyurethane acrylate from Comparative Example 2.

[0195] D11 is a difunctional polyurethane acrylate from Comparative Example 3.

[0196] Additive E consists of the following components: 0.5 parts leuco crystal violet, 0.05 parts malachite green, 0.8 parts p-toluenesulfonamide, and 0.03 parts 2,6-di-tert-butyl-4-methylphenol.

[0197] The solvent consists of the following components: 8 parts acetone, 10 parts toluene, and 5 parts methanol.

[0198] Preparation of photosensitive dry film

[0199] The preparation of a photosensitive dry film using the photosensitive resin compositions listed in Table 2 includes the following steps:

[0200] The photosensitive composition slurry prepared according to Table 2 was coated onto a 15μm thick polyethylene terephthalate (PET) support film using a coating machine (model: AB4220, TQC, Netherlands). The solvent was removed by baking at 80℃ for 10 minutes. After baking, the thickness of the photosensitive layer was controlled at 30μm. Then, a polyethylene film (PE) was applied for protection to obtain a photosensitive dry film.

[0201] Preparation of resist patterned substrates

[0202] The substrate with resist pattern was prepared using the photosensitive compositions of Examples 9-16 and Comparative Examples 4-6 as shown in Table 2. The process is as follows:

[0203] (1) Photosensitive layer formation process: A photosensitive layer is formed on a substrate using a photosensitive composition;

[0204] (2) Exposure process: Irradiate a portion of the above photosensitive layer with active light to photocur the above area to form a cured area;

[0205] (3) Development process: Remove the portion of the photosensitive layer other than the cured area from the substrate to form a resist pattern on the substrate.

[0206] The operating conditions for each process are explained in detail below.

[0207] Photosensitive layer formation process: Using a copper-clad laminate with a 35μm thick rolled 1.2mm thick copper foil, after surface adjustment and preheating to 80°C, while peeling off the PE protective film of the photosensitive dry film obtained from each embodiment or comparative example, the above-mentioned photosensitive resin composition is laminated onto the copper-clad laminate using a hot roller laminator (Zhisheng Technology Co., Ltd., CSL-M25E) at a roller temperature of 110°C, an air pressure of 0.35MPa, and a lamination speed of 1.5m / min to obtain a test substrate.

[0208] Exposure process: Exposure is performed using a direct drawing exposure machine (Xinge Microelectronics, main wavelength 405nm), and the sensitivity is tested using a Stouffer 41-level step exposure scale, with the number of exposure frames controlled between 14 and 18.

[0209] Development Process: After exposure, the PET support film is peeled off. Using an alkaline developer (manufactured by Guangzhou Julong Printed Circuit Board Equipment Co., Ltd., a dry film developer), a 1wt% Na2CO3 aqueous solution at 30°C is sprayed for twice the minimum development time to dissolve and remove the unexposed portions of the photosensitive resin layer. After development, the substrate is rinsed with pure water for 1.5 times the development time, dehydrated using an air knife, and then dried with warm air to obtain a substrate with a cured film for evaluation. The minimum development time is the shortest time required for complete dissolution of the unexposed photosensitive resin layer.

[0210] Evaluation Project

[0211] 1. Sensitivity Evaluation

[0212] On the above-mentioned film-coated test substrate, a Stouffer 41-level stepped exposure scale was placed for photosensitivity testing. After the exposure process, the test substrate was left to stand for more than 20 minutes, then the PET film layer was peeled off, and a 1.0 wt% sodium carbonate aqueous solution was sprayed at 30°C to remove the unexposed resist layer. The development time was 2.0 times the minimum development time. After the above operation, a cured film obtained by curing the photosensitive resin composition was formed on the substrate surface. The exposure energy (mJ / cm) when the number of residual segments of the stepped exposure scale obtained by the cured film was 16. 2 The photosensitivity of the photosensitive resin composition was evaluated, with a smaller value indicating better photosensitivity.

[0213] 2. Adhesion Evaluation

[0214] On the aforementioned test substrate after coating, using photomask data with a wiring pattern of n:400 (unit: μm) linewidth / spacing width, exposure was performed at an energy level that ensured a residual stage number of 16 after development using a Stouffer 41-stage exposure ruler. After the development process, the resist pattern was observed using an optical microscope, and the minimum linewidth at which a complete cured resist line was formed was used as the adhesion value to evaluate adhesion (μm). The smaller this value, the better the adhesion.

[0215] 3. Resolution Evaluation

[0216] On the aforementioned test substrate after coating, photomask data with a linewidth / spacing width of n:n (unit: μm) was used to expose the substrate at an energy level that ensured a residual stage number of 16 after development using a Stouffer 41-stage exposure ruler. After the development process, the resist pattern was observed using an optical microscope. The minimum linewidth at which a complete cured resist line was formed was used as the adhesion value to evaluate adhesion (μm). The smaller this value, the better the resolution.

[0217] 4. Evaluation of the ability to cover holes

[0218] After removing the protective film from the obtained dry film resist, it was laminated onto a 1.6 mm copper-clad board (containing 120 circular holes with a diameter of 6 mm). It was exposed at an exposure energy of 18 photosensitive frames and developed three times with a development time of 2.0 times the shortest development time. The hole breakage rate was then calculated.

[0219] Evaluation results

[0220] The test results for evaluation items 1-4 of Examples 9-16 and Comparative Examples 4-6 are shown in Table 2.

[0221]

[0222] As shown in Table 2, the performance comparison between Examples 9-16 and Comparative Examples 4-6 fully demonstrates that the addition of the photocurable polyurethane acrylate in the examples of this invention can significantly improve the photosensitivity, adhesion, resolution, and pore-covering performance of the photosensitive dry film. This indicates that the photocurable polyurethane acrylate in this invention can further improve the overall performance of the photosensitive dry film compared to existing polyurethane monomers. Even with adjustments to the component ratios and the type of photocurable polyurethane acrylate in Examples 15-16, the prepared photosensitive dry films still exhibit good overall performance.

[0223] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A photocurable polyurethane acrylate, characterized in that, The photocurable polyurethane acrylate contains at least one structure as described in Formula I: In Formula I: 'R is hydrogen or methyl; R is as shown in Formula II: In formula II, The term indicates the site connected to the main structural formula I. R1 is one of the following: a C2-C4 straight-chain alkyl group, a C2-C8 straight-chain ether alkane, or a C4-C12 straight-chain ester alkane; R2 is one of the following: an aryl group, a substituted aryl group, a C5-C8 straight-chain alkyl group, a cycloalkyl group, or a substituted cycloalkyl group; R3 is one of the following: a C4-C8 alkyl group, a C4-C8 substituted alkyl group, a phenyl group, or a substituted phenyl group; R4 is a C2-C4 straight-chain alkyl group; R5 is hydrogen or methyl; and n ranges from 1 to 80.

2. The method for preparing photocurable polyurethane acrylate according to claim 1, characterized in that, Includes the following steps: Step S1: After mixing compound 1 and compound 2, a reaction solution is obtained and heated to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain compound 3, wherein the molar ratio of compound 1 to compound 2 is 1:(1.8~2.2). Step S2: Dissolve compound 3, compound 4 and catalyst in solvent and heat to react until the mass percentage of -NCO groups in the reaction solution reaches half of the initial value, to obtain a reaction solution containing compound 5, wherein the molar ratio of compound 4 to compound 3 is 1:(1.8~2.2). Step S3: After dissolving compound 6 in a solvent, add it to the reaction solution containing compound 5 and heat the reaction until the mass percentage of -NCO groups in the reaction solution is 0, to obtain a reaction solution containing compound 7, wherein the molar ratio of compound 5 to compound 6 is 1:(1.8~2.2). Step S4: After dissolving compound 8 in a solvent, add it to the reaction solution containing compound 7 and react until the acid value in the reaction solution is 0. Add a poor solvent dropwise to the reaction solution to precipitate the product. After filtration, washing and drying, obtain a photocurable polyurethane acrylate, wherein the molar ratio of compound 8 to compound 7 is 1:(2.7~3.3). The synthesis route is as follows: 。 3. The method for preparing photocurable polyurethane acrylate according to claim 2, characterized in that, In steps S1, S2 and S3, the heating reaction temperature is 50~100℃ and the heating reaction time is 1~3h; in step S4, the reaction temperature is 0~100℃ and the reaction time is 10~120min.

4. The method for preparing photocurable polyurethane acrylate according to claim 2, characterized in that, In step S1, compound 1 is selected from one of poly(ethylene adipate), polyethylene adipate, polycarbonate diol, polycaprolactone, polyethylene glycol, polypropylene glycol, and polybutanediol. The number-average molecular weight of compound 1 is 400-4000; Compound 2 is one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diisocyanate dicyclohexylmethane, cyclohexane-1,4-diisocyanate, 1,4-cyclohexane dimethyl diisocyanate, 4,4'-diisocyanate diphenylmethane, 2,4'-diisocyanate diphenylmethane, 2,2'-diisocyanate diphenylmethane, and naphthalene diisocyanate; In step S2, compound 4 is one of 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, and 3,4-dihydroxybenzoic acid. In step S3, compound 6 is one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; In step S4, compound 8 is one or more of trimethylolpropane-tris[3-(2-methylacridinyl)propionate] and trimethylolpropane-tris(3-acridinyl)propionate.

5. The method for preparing photocurable polyurethane acrylate according to claim 2, characterized in that, In step S2, the catalyst is DBTDL, and the amount of catalyst added is 0.01~0.1 wt% of the mass of compound 3.

6. The method for preparing photocurable polyurethane acrylate according to claim 2, characterized in that, In steps S2, S3, and S4, the solvent is one or more of acetone, butanone, cyclohexanone, ethyl acetate, toluene, xylene, N,N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, and dipropylene glycol monomethyl ether; in step S4, the undesirable solvent is n-hexane.

7. A photosensitive resin composition, characterized in that, Includes the photocurable polyurethane acrylate as described in claim 1.

8. The photosensitive resin composition according to claim 7, characterized in that, The photosensitive resin composition comprises, by weight parts: 50-65 parts of alkali-soluble resin; 35-50 parts of photocurable polyurethane acrylate; 2-5 parts of photoinitiator; and 0.1-1 parts of photosensitizer.

9. A photosensitive dry film, characterized in that, The photosensitive dry film comprises, from bottom to top, a PET layer, a photosensitive etchant layer, and a PE layer, wherein the photosensitive etchant layer is prepared from the photosensitive resin composition of claim 7 or 8.

10. The application of the photosensitive dry film according to claim 9 in printed circuit boards, lead frames or semiconductor packaging substrates.

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