Oxime ester fluorene photoinitiators, photocurable resin compositions and applications

Abstract

The present invention provides an oxime ester fluorene-based photoinitiator, a photocurable resin composition and applications thereof. The oxime ester fluorene-based photoinitiator contains a 4,6-alkoxy-substituted triazine ring group, and the oxime ester fluorene-based photoinitiator has a structure shown in the general formula (I): Introducing a triazine ring group at the 7-position of fluorene can expand the range of electron delocalization in the conjugated structure of the existing oxime ester fluorene chemical structure, improve the structural stability, and thus is beneficial to significantly improving the photosensitivity and yellowing resistance of the oxime ester fluorene-based photoinitiator. Introducing specific types of substituents at the 4-position and 6-position of the triazine ring in the general formula (I) is beneficial to further improving its solubility. The oxime ester fluorene-based photoinitiator with the above structure has the characteristics of low yellowing and excellent solubility. In addition, the above oxime ester fluorene-based photoinitiator can be used in a UV-LED photocuring system (especially under the action of a 365 nm light source) to significantly improve the yellowing resistance performance.

Description

Technical Field

[0001] The present invention relates to the field of organic chemistry, and in particular, to an oxime ester fluorene-based photoinitiator, a photocurable resin composition and applications thereof. Background Art

[0002] Flat panel display technology is widely used in aspects such as televisions, computers, mobile phones, in-vehicle devices, aircraft, and high-speed rail information displays. There are two types of flat panel display photoresists: color photoresists and black photoresists. Both of these photoresists are key materials for realizing flat panel displays. A flat panel display photoresist consists of a photoinitiator, a resin, a monomer, a pigment, an additive, etc. The structures of the photoresists, resins, and monomers with different display resolutions do not differ much. The most important difference lies in the structure of the photoinitiator. The higher the clarity of the flat panel display, the higher the required photosensitivity of the photoresist photoinitiator. The photoinitiator is a key raw material for high-definition flat panel display processing.

[0003] The development of the high-definition display field has put forward higher requirements for photoresists, not only requiring higher photosensitivity, but also better resolution and better color saturation. This requires the photoinitiator to have high photosensitive performance on the one hand and low yellowing characteristics on the other hand. However, most of the existing oxime ester initiators have too large a yellowing coefficient and poor yellowing resistance, which will reduce the color saturation of the display screen and cannot be used. The market urgently needs photoinitiator products with low yellowing and high sensitivity, and the solubility of the initiator is a key factor determining its practical application.

[0004] On this basis, it is of great significance to research and develop a photoinitiator product with good solubility and simultaneously having low yellowing and high photosensitivity. Summary of the Invention

[0005] The main object of the present invention is to provide an oxime ester fluorene-based photoinitiator, a photocurable resin composition and applications thereof, so as to solve the problem that the existing photoinitiators cannot simultaneously meet the requirements of high solubility, high photosensitivity, and good yellowing resistance.

[0006] To achieve the above object, on the one hand, the present invention provides an oxime ester fluorene-based photoinitiator, which contains a 4,6-alkoxy-substituted triazine ring group, and the oxime ester fluorene-based photoinitiator has a structure shown in general formula (I):

[0007]

[0008] In general formula (I), R1 and R1' are the same or different, and R1 and R1' are each independently selected from a hydrogen atom, a halogen, an alkyl group having C1 to C 10 alkyl, an aryl group having C4 to C 10 aryl or an alkynyl group having C2 to C 10an alkenyl group, wherein the alkyl, aryl, and alkenyl groups may each be interrupted by O, N, or a carbonyl group; or R1 and R1' may also be joined to form a ring; R2 and R3 are each independently selected from R2 and R3 are each independently selected from a straight-chain or branched-chain alkyl group having 1 to C 20 of a straight-chain or branched-chain alkyl group having 1 to C3 to C 20 of a cycloalkyl group having 3 to C8, a C1 to C alkyl group substituted with a cycloalkyl group having 3 to C8 10 of an alkyl group having 1 to C1 to C 20 an alkyl group having 3 to C8 substituted with an alkyl group, a phenyl group, a group obtained by substituting at least one hydrogen atom of the phenyl group with a C1 to C4 alkyl group, a C1 to C4 alkoxy group, a group obtained by substituting one or more hydrogen atoms of the C1 to C4 alkoxy group with a fluorine atom, a furyl group, a thienyl group, a C1 to C4 alkyl group capped with a furyl group, or a C1 to C4 alkyl group capped with a thienyl group; R4 and R5 are each independently selected from a C1 to C5 alkyl group.

[0009] Further, in general formula (I), R2 is selected from a C1 to C 10 an alkyl group having 3 to C8 substituted with a cycloalkyl group, a phenyl group, a naphthyl group, a furyl group, or a thienyl group; R3 is selected from a C1 to C 10 of a straight-chain or branched-chain alkyl group having 1 to C, a phenyl group, or a group obtained by substituting at least one hydrogen atom of the phenyl group with a C1 to C4 alkyl group.

[0010] Further, R1 and R1' are selected from a straight-chain alkyl group having 1 to C5.

[0011] Further, R1 and R1' are selected from a branched-chain or straight-chain alkyl group having 1 to C4; R2 is selected from a cyclohexane substituted with a C1 to C4 alkylene group, a cyclopentane substituted with a C1 to C4 alkylene group, a phenyl group, a 1-naphthyl group, an α-furyl group, or an α-thienyl group; R3 is selected from a methyl group, an ethyl group, a phenyl group, or a 2-methylphenyl group; R4 and R5 are selected from a straight-chain or branched-chain alkyl group having 1 to C4.

[0012] Further, the oxime ester fluorene-based photoinitiator is selected from one or more of the following compounds 1 to compound 10:

[0013]

[0014]

[0015] To achieve the above object, another aspect of the present invention further provides a photocurable resin composition, which includes a photoinitiator, an alkali-soluble resin, and a polymerizable monomer, wherein the photoinitiator includes the above-mentioned oxime ester fluorene-based photoinitiator provided in the present application.

[0016] Furthermore, the photocurable resin composition comprises 0.5 to 10 parts of an oxime ester fluorene-based photoinitiator, 20 to 80 parts of an alkali-soluble resin, and 20 to 80 parts of a polymerizable monomer; preferably, the photocurable resin composition further comprises 0 to 200 parts of a solvent.

[0017] Another aspect of the present invention provides an application of the above-mentioned oxime ester fluorene-based photoinitiator provided in the present application or the above-mentioned photocurable resin composition provided in the present application in the field of photocuring.

[0018] Applying the technical solution of the present invention provides an oxime ester fluorene-based photoinitiator having the structure shown in the above general formula (I). Introducing a triazine ring group at the 7-position of fluorene in the chemical structure of the oxime ester fluorene can expand the electron delocalization range in the conjugated structure of the existing oxime ester fluorene chemical structure, greatly improving the structural stability, thereby being conducive to significantly improving the photosensitivity and yellowing resistance of the oxime ester fluorene-based photoinitiator. Introducing specific types of substituents at the 4-position and 6-position of the triazine ring in the structure shown in the general formula (I) is beneficial to further improving the solubility of the oxime ester fluorene-based photoinitiator. Due to the good alkali solubility of the oxime ester fluorene-based photoinitiator with the above structure, when it is applied to the photocurable composition, it can well improve the curing efficiency under light source irradiation and has the characteristics of low yellowing and excellent solubility. In addition, the above oxime ester fluorene-based photoinitiator can be used in a UV-LED photocuring system (especially under the action of a 365 nm light source) to significantly improve the yellowing resistance performance. Detailed implementation manners

[0019] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0020] As described in the background art, the existing photoinitiators have problems of low solubility, low photosensitivity, and poor yellowing resistance. To solve the above technical problems, the present application provides an oxime ester fluorene-based photoinitiator, which contains a 4,6-alkoxy-substituted triazine ring group, and the oxime ester fluorene-based photoinitiator has the structure shown in the general formula (I):

[0021]

[0022] In the general formula (I), R1 and R1' are the same or different, and R1 and R1' each independently include but are not limited to a hydrogen atom, a halogen, an alkyl group having 1 to C 10 alkyl, an aryl group having 4 to C 10 aryl or an alkenyl group having 2 to C 10 alkenyl, wherein the alkyl group, the aryl group, and the alkenyl group can each be interrupted by O, N, or a carbonyl group; or R1 and R1' can also be connected to form a ring; R2 and R3 each independently include but are not limited to R2 and R3 each independently include but are not limited to an alkyl group having 1 to C20 linear or branched alkyl group having 1 to 5 carbon atoms, cycloalkyl group having 3 to 8 carbon atoms, C1-C 20 alkyl group substituted by cycloalkyl group having 3 to 8 carbon atoms, C1-C 10 alkyl group having 1 to 5 carbon atoms, C1-C 20 cycloalkyl group having 3 to 8 carbon atoms substituted by C1-C4 alkyl group, phenyl group, group obtained by substituting at least one hydrogen atom of phenyl group with C1-C4 alkyl group, C1-C4 alkoxy group, group obtained by substituting one or more hydrogen atoms of C1-C4 alkoxy group with fluorine atom, furyl group, thienyl group, C1-C4 alkyl group capped with furyl group, or C1-C4 alkyl group capped with thienyl group; R4 and R5 each independently include, but are not limited to, C1-C5 alkyl group.

[0023] Introducing a triazine ring group at the 7-position of fluorene in the chemical structure of oxime ester fluorene can expand the range of electron delocalization in the conjugated structure of the existing oxime ester fluorene chemical structure, greatly improve the stability of the structure, and thus is conducive to significantly improving the photosensitivity and yellowing resistance of oxime ester fluorene photoinitiators. Introducing specific types of substituents at the 4-position and 6-position of the triazine ring in the structure shown in the general formula (I) is beneficial to further improving the solubility of oxime ester fluorene photoinitiators. Due to the good alkali solubility of the oxime ester fluorene photoinitiators with the above structure, when they are applied to a photocurable composition, the curing efficiency under light source irradiation can be well improved, and they have the characteristics of low yellowing and excellent solubility. In addition, the above oxime ester fluorene photoinitiators can be used in a UV-LED photocuring system (especially under the action of a 365 nm light source) to significantly improve the yellowing resistance performance.

[0024] In a preferred embodiment, in the above general formula (I), R2 and R3 each independently include, but are not limited to, C1-C 10 cycloalkyl group having 3 to 8 carbon atoms substituted by C1-C4 alkyl group, phenyl group, naphthyl group, furyl group or thienyl group; R3 includes, but is not limited to, C1-C 10 linear or branched alkyl group having 1 to 5 carbon atoms, phenyl group or group obtained by substituting at least one hydrogen atom of phenyl group with C1-C4 alkyl group. Compared with other types of groups, limiting the types of R2 and R3 within the above ranges is beneficial to further improving the photosensitivity, solubility and yellowing resistance performance of oxime ester fluorene photoinitiators.

[0025] In a preferred embodiment, R1 and R1' each independently include, but are not limited to, C1-C5 linear alkyl groups. Compared with other types of groups, limiting the types of R1 and R1' within the above ranges is beneficial to further improving the photosensitivity, solubility and yellowing resistance performance of oxime ester fluorene photoinitiators.

[0026] To further improve the photosensitivity and solubility of oxime ester fluorene-based photoinitiators, preferably, R1 and R1' include, but are not limited to, branched or branched-chain alkyl groups with 1 to 4 carbon atoms; R2 includes, but is not limited to, cyclohexane substituted with C1-C4 alkylene, cyclopentane substituted with C1-C4 alkylene, phenyl, 1-naphthyl, α-furyl, or α-thienyl; R3 includes, but is not limited to, methyl, ethyl, phenyl, or 2-methylphenyl; R4 and R5 are both straight-chain or branched-chain alkyl groups with 1 to 4 carbon atoms. Compared with other types of groups, limiting the types of R1, R1', R2, R3, R4, and R5 within the above ranges is beneficial to further improving the photosensitivity, solubility, and yellowing resistance of oxime ester fluorene-based photoinitiators.

[0027] In a preferred embodiment, the oxime ester fluorene-based photoinitiator includes, but is not limited to, one or more of the following Compounds 1 to 10:

[0028]

[0029]

[0030] Compared with combinations of other substituents, the above Compounds 1 to 10 have high photosensitivity, high curing efficiency, and excellent yellowing resistance, and can be used in UV-LED photocuring systems. Especially as an initiator under the action of a 365 nm light source, it can significantly improve the yellowing resistance.

[0031] The second aspect of this application also provides a preferred preparation method for an oxime ester fluorene-based photoinitiator, and its synthesis route is as follows:

[0032]

[0033] The above preparation method for the oxime ester fluorene-based photoinitiator includes:

[0034] S1, under the action of n-butyllithium, a halogenated fluorene in which the 9-position of fluorene is substituted by R1 and R1' reacts with a borate compound in a first solvent to undergo a boration reaction and a hydrolysis reaction, obtaining a first intermediate; the first intermediate is R1 and R1' have the same definitions as R1 and R1' in the structure shown by the general formula (I); preferably, the temperature of the boration reaction is -50 to -78 °C, and the hydrolysis reaction also includes 1 mol / L dilute hydrochloric acid or the pH of the hydrolysis reaction is 4 to 5;

[0035] S2, under the condition of a first catalyst, the first intermediate reacts with a 2-halo-4,6-alkoxy-substituted triazine compound in a second solvent to undergo a Suzuki coupling reaction, obtaining a second intermediate; the 2-halo-4,6-alkoxy-substituted triazine compound is The second intermediate is wherein R1, R1’, R4 and R5 have the same definitions as R1, R1’, R4 and R5 in the structure represented by general formula (I) respectively, and X is a halogen atom; preferably, the temperature of the Suzuki coupling reaction is 60-120 °C;

[0036] S3, under the condition of a second catalyst, reacting a second intermediate with a propionyl chloride compound in a third solvent to obtain a third intermediate; the third intermediate is Preferably, the temperature of the Friedel-Crafts acylation reaction is -10-40 °C, more preferably 0-5 °C;

[0037] S4, under the action of concentrated hydrochloric acid, reacting the third intermediate with nitrous acid or an alkyl nitrite to carry out an oximation reaction to obtain a fourth intermediate; the fourth intermediate is wherein R1, R1’, R4 and R5 have the same definitions as R1, R1’, R4 and R5 in the structure represented by general formula (I) respectively; preferably, the temperature of the oximation reaction is -15-50 °C, more preferably 0-25 °C;

[0038] S5, in a fourth solvent, reacting the fourth intermediate with an acylating agent under the action of a base to carry out an esterification reaction to obtain the oxime ester fluorene-based photoinitiator provided in the present application;

[0039] The oxime ester fluorene-based photoinitiator has the structure represented by general formula (I):

[0040]

[0041] In general formula (I), R1, R1’, R2, R3, R4 and R5 have the same definitions as the foregoing respectively; preferably, the temperature of the oximation reaction is -15-50 °C, more preferably 0-25 °C.

[0042] In a preferred embodiment, the borylation reaction is carried out in a first solvent. There is no special limitation on the type of the first solvent as long as it can dissolve the reaction reagents and has no adverse effect on the borylation reaction. For example, the first solvent can be tetrahydrofuran (THF), diethyl ether or 1,4-dioxane, etc., and preferably tetrahydrofuran (THF).

[0043] In a preferred embodiment, the second solvent is selected according to the actual situation of the reaction system of the Suzuki coupling reaction (such as the types of reaction reagents). There is no particular limitation on the type of the second solvent, as long as the second solvent can dissolve the reaction reagents of the Suzuki coupling reaction and has no adverse effect on the Suzuki coupling reaction. For example, the second solvent can be tetrahydrofuran (THF), dioxane, N,N-dimethylformamide (DMF), dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), etc. In a preferred embodiment, in the Suzuki coupling reaction, the first catalyst includes but is not limited to palladium catalysts.

[0044] In a preferred embodiment, there is no particular limitation on the type of the third solvent used in the Friedel-Crafts acylation reaction, as long as it can dissolve the reaction reagents and has no adverse effect on the reaction. For example, it can be dichloromethane, dichloroethane, preferably dichloromethane. In a preferred embodiment, in the Friedel-Crafts acylation reaction, the second catalyst includes but is not limited to aluminum chloride.

[0045] In a preferred embodiment, in the esterification reaction, the fourth solvent includes but is not limited to one or more selected from the group consisting of diethyl ether, acetonitrile, tert-butyl methyl ether, tetrahydrofuran, vinyl acetate, toluene, xylene, acetone, methyl ethyl ketone, dichloromethane, chloroform, chlorobenzene, dimethylacetamide, and dimethylformamide.

[0046] In a preferred embodiment, in the esterification reaction, the acylating agent includes but is not limited to acyl halides and / or acid anhydride compounds. Preferably, the acylating agent includes but is not limited to one or more selected from the group consisting of cyclohexanecarbonyl chloride, 2-propylvaleryl chloride, 3,5,5-trimethylhexanoyl chloride, 3-chloropropionyl chloride, 5-chlorovaleryl chloride, 3-chloro-2,2-dimethylpropionyl chloride, 6-bromohexanoyl chloride, methoxyacetyl chloride, ethoxyacetyl chloride, butoxyacetyl chloride, 3-(methylthio)propionyl chloride, (2-butoxyethoxy)acetyl chloride, benzoyl chloride, toluoyl chloride, 3,5-dimethylbenzoyl chloride, 4-methoxybenzoyl chloride, 4-cyanobenzoyl chloride, 4-nitrobenzoyl chloride, 4-phenylbenzoyl chloride, chlorobenzoyl chloride, phenylacetyl chloride, phenylpropionyl chloride, chlorophenylacetyl chloride, 4-phenylbutyryl chloride, 6-phenylhexanoyl chloride, nitrophenylacetyl chloride, phenoxyacetyl chloride, phenoxypropionyl chloride, chlorophenoxyacetyl chloride, nitrophenoxyacetyl chloride, 2-thiophenecarbonyl chloride, thiophene-2-acetyl chloride, nicotinoyl chloride, 2-furoyl chloride, quinolinecarbonyl chloride, naphthoyl chloride, 2-ethoxy-1-naphthoyl chloride, anthracenecarbonyl chloride, acetic anhydride, propionic anhydride, capric anhydride, stearic anhydride, isobutyric anhydride, pivalic anhydride, and 4-methoxyphenylacetic anhydride.

[0047] In a preferred embodiment, in the esterification reaction, the base includes, but is not limited to, one or more of the group consisting of triethylamine, pyridine, diisopropylethylamine, potassium hydroxide, sodium hydroxide, and sodium hydride.

[0048] In a preferred embodiment, in the esterification reaction, the alkyl nitrite includes, but is not limited to, one or more of the group consisting of methyl nitrite, ethyl nitrite, isopropyl nitrite, butyl nitrite, and isoamyl nitrite.

[0049] The third aspect of the present application also provides a photocurable resin composition, which includes a photoinitiator, an alkali-soluble resin, and a polymerizable monomer, wherein the photoinitiator includes the above-mentioned oxime ester fluorene-based photoinitiator provided by the present application.

[0050] Under the irradiation of a light source, compared with other types of photoinitiators, the above-mentioned high-sensitivity oxime ester fluorene-based photoinitiator provided by the present application can more efficiently absorb the energy from the light source and generate more active free radicals, thereby more rapidly initiating the photopolymerization reaction of the monomers in the photocuring system. After further curing reaction, a photocurable resin can be obtained. At the same time, the above-mentioned oxime ester fluorene-based photoinitiator with a specific structure has good compatibility with the alkali-soluble resin and the polymerizable monomer, which is beneficial to further improving the curing efficiency of the photocurable resin. In short, the above-mentioned photocurable resin composition provided by the present application has the characteristics of high sensitivity, high curing efficiency, and excellent yellowing resistance; moreover, the above-mentioned oxime ester fluorene-based photoinitiator can be used in a UV-LED photocuring system (especially under the action of a 365 nm light source) to significantly improve the yellowing resistance.

[0051] In a preferred embodiment, the photocurable resin composition includes 0.5 to 10 parts of the oxime ester fluorene-based photoinitiator, 20 to 80 parts of the alkali-soluble resin, and 20 to 80 parts of the polymerizable monomer. Compared with other dosages, limiting the dosages of the oxime ester fluorene-based photoinitiator, the alkali-soluble resin, and the polymerizable monomer within the above ranges is beneficial to further improving the curing efficiency of the photocurable resin composition and further enhancing the yellowing resistance, especially improving the yellowing resistance under the action of a 365 nm light source.

[0052] In order to further improve the compatibility between the above-mentioned oxime ester fluorene-based photoinitiator with a specific structure and the alkali-soluble resin and the polymerizable monomer, and at the same time, further improve the curing efficiency of the photocurable resin composition and the yellowing resistance of the photocurable resin, preferably, the photocurable resin composition further includes 0 to 200 parts of a solvent.

[0053] In a preferred embodiment, the polymerizable monomer includes, but is not limited to, one or more selected from the group consisting of methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, and cetyl methacrylate.

[0054] In a preferred embodiment, the alkali-soluble binder resin includes, but is not limited to, a resin prepared by copolymerizing one or more selected from the group consisting of C4-C 20 (meth)acrylate monomers containing polymerizable groups, C4-C 20 epoxy monomers, C4-C 20 oxa monomers, and C4-C 20 anhydride monomers. Preferably, the polymerizable group includes, but is not limited to, one or more selected from the group consisting of allyl, epoxy, oxa, and anhydride. When the polymerizable group is an oxa group, the oxa group is a tetracyclic epoxy group.

[0055] In a preferred embodiment, the solvent includes, but is not limited to, one or more selected from the group consisting of ethyl acetate, acetone, benzene, toluene, xylene, cyclohexane, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monopropyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, diethylene glycol methyl ether acetate, diethylene glycol butyl ether acetate, and ethyl 3-ethoxypropionate.

[0056] In an alternative embodiment, the fluorene main structure in the above-mentioned oxime ester fluorene-based photoinitiator provided by the present application can be replaced with a main group such as carbazole, diphenyl sulfide, or biphenyl.

[0057] The fourth aspect of the present application also provides an application of the above-mentioned oxime ester fluorene-based photoinitiator provided by the present application, or the above-mentioned photocurable resin composition provided by the present application, in the field of photocuring.

[0058] Under the irradiation of a light source, compared with other types of photoinitiators, the above-mentioned high-sensitivity oxime ester fluorene-based photoinitiators provided by the present application can more efficiently absorb the energy from the light source and generate more active free radicals, thereby more rapidly initiating the photopolymerization reaction of monomers in the photocuring system. After further curing reactions, a photocured resin can be obtained. At the same time, the above-mentioned oxime ester fluorene-based photoinitiators with specific structures have good compatibility with alkali-soluble resins and polymerization monomers, which is beneficial to further improving the curing efficiency of the photocured resin. In summary, the above-mentioned photocured resin composition provided by the present application has the characteristics of high sensitivity, high curing efficiency, and excellent yellowing resistance; moreover, the above-mentioned oxime ester fluorene-based photoinitiators can be used in UV-LED photocuring systems (especially under the action of a 365nm light source) to significantly improve the yellowing resistance.

[0059] The above-mentioned oxime ester fluorene-based photoinitiators provided by the present application can be applied in fields such as paints, coatings, inks, and molding materials, including but not limited to: coatings applied on substrates such as plastics, metals, glass, ceramics, wood, and walls; photocuring adhesives, photo-decomposable coatings; printing inks for screen printing, offset printing, intaglio printing, etc.; photocuring inks for inkjet printing and 3D printing; film materials such as hard coating agents, antifouling films, antireflection films, impact buffer films, interlayer insulating films, light extraction films, brightness enhancement films, and sealing films; optical components such as lenses, lens arrays, optical waveguides, light guide plates, light diffusing plates, and diffraction elements; optical molding resins such as color filters and black matrices (light-shielding films); optical recording media such as holographic imaging materials; photoresists for electronic circuits and semiconductor manufacturing; light spacers; rib walls; materials for nanoimprinting; quantum dots, etc.

[0060] The following further describes the present application in detail with specific examples, and these examples should not be construed as limiting the scope claimed by the present application.

[0061] Example 1

[0062] The synthesis route of Compound 1 in this Example 1 is as follows:

[0063]

[0064] A preparation method of an oxime ester fluorene-based photoinitiator includes the following steps:

[0065] (1) Preparation of the first intermediate

[0066]

[0067] Add 150g, 0.42mol of 2-bromo-9,9-dibutylfluorene and 900mL of tetrahydrofuran (first solvent) to a four-necked flask, stir to dissolve, and cool to -78°C. Add 176mL of tetrahydrofuran solution of n-butyl lithium (2.5mol / L) dropwise; after the dripping is complete, keep warm and continue stirring for 30min. Then add 79.0g of triisopropyl borate, allow the above reaction system to naturally warm up to room temperature, and continue stirring for 1h. Add 500mL of water to the above reaction system to quench (end the reaction), then add 420mL of dilute hydrochloric acid (1mol / L), adjust the pH to 5 and start the hydrolysis reaction of triisopropyl borate, and stir at room temperature for 30min. Add ethyl acetate to the system after the above reaction, stir and stand for stratification, and separate the upper organic phase; the organic phase is washed 3 times with 500mL of water, and the organic phase is concentrated to obtain 106.4g of yellow oil, i.e., the first intermediate 1b.

[0068] The yield of the first intermediate was 78.6%. The first intermediate was directly used as the raw material for the next step reaction.

[0069] (2) Preparation of the Second Intermediate

[0070]

[0071] The 106.4 g and 0.33 mol of the first intermediate obtained in the previous step were dissolved in 500 mL of DMF (the second solvent), and then 63.7 g of 2-chloro-4,6-dimethoxytriazine, 3.8 g of Pd(PPh3)4, 86.6 g of triphenylphosphine and 66.8 g of triethylamine were added in sequence. The reaction tank system of the Suzuki coupling reaction was heated to 80°C and stirred for 6 hours to obtain a reaction solution. The reaction solution was filtered with diatomaceous earth while hot, 500 mL of water was added to the obtained filtrate, and then extracted with ethyl acetate; the upper organic phase was washed with water three times, the organic phase was concentrated, and the obtained light yellow oil was dissolved in methanol, stirred at room temperature for 30 minutes, and then cooled to 5-10°C and continued to stir for 1 hour to precipitate a milky white solid. After filtration, 99.5 g of white solid was collected, which was the second intermediate 1c.

[0072] The yield of the second intermediate was 72.2% and the purity was 98.46%. The obtained second intermediate was directly used as the raw material for the next step reaction.

[0073] (3) Preparation of the Third Intermediate

[0074]

[0075] Under nitrogen protection, 83.5 g (0.2 mol) of the second intermediate and 400 mL of dichloromethane (the third solvent) were successively added to the reaction flask, stirred until dissolved and clear, and then 36.7 g of cyclohexylpropionyl chloride was added. 29.3 g of aluminum chloride (the second catalyst) was added at room temperature, and stirring was continued for 1 h. The reaction solution of the Friedel-Crafts acylation reaction was added to ice water, stirred for 30 min, allowed to stand for liquid separation, and the lower organic phase was separated out. The organic phase was washed with water until neutral, concentrated to obtain a residue, then methanol was added, stirred until a solid precipitated, cooled to 5 - 10 °C, and stirring was continued for 2 h for crystal precipitation. Filtered, the solid was collected to obtain 82.6 g of a pale white solid, namely the third intermediate 1d.

[0076] The yield of the third intermediate was 74.3%, and the purity was 97.79%. The obtained third intermediate was directly used as the raw material for the next step of the reaction.

[0077] (4) Preparation of the fourth intermediate

[0078]

[0079] 80 g (0.14 mol) of the third intermediate and 480 mL of ethyl acetate were added to the reaction flask, stirred until dissolved and clear; then 24.6 g of isoamyl nitrite and 21 mL of concentrated hydrochloric acid were added, and stirred at room temperature for 2 h. The reaction was stopped, 500 mL of water was added, and stirring was continued for 30 min. Allowed to stand for liquid separation, the lower organic phase was separated out, washed with water until neutral, and the organic phase was concentrated. The obtained viscous substance was dissolved in methanol, stirred thoroughly at room temperature for 4 h, and a light yellow solid precipitated. The temperature was further lowered to 5 - 10 °C and stirred for 2 h. After filtration, 56.2 g of a yellow solid was collected, namely the fourth intermediate 1e.

[0080] The yield of the fourth intermediate was 68.7%, and the purity was 96.75%. The obtained fourth intermediate was directly used as the raw material for the next step of the reaction.

[0081] (5) Preparation of compound 1

[0082]

[0083] Under nitrogen protection, 50 g of the fourth intermediate (0.085 mol), 9.5 g of triethylamine (TEA) and 200 mL of dichloromethane were added to the reaction flask and stirred until dissolved and clear. 9.2 g of acetic anhydride was added dropwise at room temperature and stirred for 3 h. 300 g of water was added to the reaction solution and stirred for 30 min. It was allowed to stand for phase separation, and the lower organic phase was separated out, washed with water until neutral, and the organic phase was concentrated to obtain a solid. The obtained solid was dissolved in methanol and stirred for 1 h, and a solid gradually precipitated. The temperature was further lowered to 5 - 10 °C and stirred for 2 h. The filter cake was obtained by filtration, and the filter cake was washed with methanol to obtain the crude product of Compound 1. The crude product was dissolved in 100 mL of acetone and added to 300 mL of methanol, and stirred for another 1 h in an ice bath. The filter cake was obtained by filtration, and the filter cake was rinsed with methanol, and the filter cake was collected to obtain 42.3 g of a light yellow solid, namely Compound 1.

[0084] The yield of Compound 1 was 79.4%, and the purity was 99.28%.

[0085] The chemical structure of Compound 1 was confirmed by 1H-NMR and MS respectively, and the characterization results were as follows:

[0086] (1) The 1H-NMR data of Compound 1 were as follows: 1H-NMR (500 MHz, Chloroform-d)

[0087] δ 7.96 - 7.81 (m, 3H), 7.76 (d, J = 1.4 Hz, 1H), 7.58 (dd, J = 7.4, 1.5 Hz, 1H), 3.91 (s, 4H), 2.91 (d, J = 7.0 Hz, 2H), 2.15 (s, 2H), 2.01 - 1.89 (m, 3H), 1.84 (dt, J = 12.5, 7.0 Hz, 2H), 1.58 - 1.49 (m, 3H), 1.52 - 1.40 (m, 12H), 1.42 - 1.31 (m, 4H), 0.88 (t, J = 7.9 Hz, 5H).

[0088] (2) The MS data of Compound 1 were as follows: MS (m / z): 567 [M - OAc] + 。

[0089] Examples 2 to 10

[0090] According to the preparation method of the oxime ester fluorene-based photoinitiator in Example 1, by replacing the corresponding reaction raw materials or reagents, Compounds 2 to 10 were prepared. The corresponding chemical structural formulas and the 1H-NMR characterization data of Compounds 2 to 10 are listed in Table 1 below.

[0091] Table 1

[0092]

[0093]

[0094]

[0095] The following performance evaluations were conducted on Compounds 1 to 10 prepared in the above Examples 1 to 10 and existing oxime ester photoinitiators (Compound A and Compound B), including:

[0096] 1. Solubility performance test

[0097] The solubility of oxime ester fluorene photoinitiators in propylene glycol methyl ether acetate (PGMEA) is one of the index parameters representing their solubility performance and measuring the application performance of photoinitiators. Compounds with the structure shown in General Formula (I) were selected and compared with existing oxime ester photoinitiators (Compound A and Compound B). The solubilities of Compounds 1 to 10 and Compounds A and B in PGMEA at 25 °C were respectively tested, and the test results are shown in Table 2.

[0098] Table 2

[0099] Oxime ester fluorene photoinitiators Solubility in PGMEA (wt%) Example 1 Compound 1 >15％ Example 2 Compound 2 >15％ Example 3 Compound 3 >15％ Example 4 Compound 4 >15％ Example 5 Compound 5 >15％ Example 6 Compound 6 >15％ Example 7 Compound 7 >15％ Example 8 Compound 8 >15％ Example 9 Compound 9 >15％ Example 10 Compound 10 >15％ Comparative Example 1 Compound A <5％ Comparative Example 2 Compound B >15％ Comparative Example 3 Compound C <10％

[0100] Among them, the chemical structural formula of Compound A is: The chemical structural formula of Compound B is: Compound C:

[0101] 2. Photosensitivity performance test

[0102] It should be noted that the photocurable compositions used in the photosensitivity tests in all the examples and comparative examples of this application were prepared according to the following ratio. Among them, by weight, the photocurable composition includes: 200 parts of acrylate copolymer, 100 parts of dipentaerythritol hexaacrylate, 5 parts of photoinitiator, 900 parts of methyl ethyl ketone (solvent), 5 parts of dye blue 15 (CAS: 147-14-8), and the above acrylate copolymer (manufacturer: Changzhou Qiangli Electronic New Materials Co., Ltd.) is a copolymer of benzyl methacrylate / methacrylic acid / 2-hydroxyethyl methacrylate (molar ratio of 70:10:20), Mw = 10000.

[0103] In the above photocurable composition, the photoinitiator is the oxime ester fluorene compound shown in General Formula (I) in the foregoing content of this application or a known similar photoinitiator in the prior art for comparison. The specific formulations of all the examples and comparative examples of this application are shown in Table 3.

[0104] Table 3

[0105]

[0106]

[0107] (1) Sensitivity test

[0108] The above-mentioned photocurable composition was stirred in the dark and coated on the PET film with a 6# wire rod to form a coating with a wet film thickness of about 6 μm. A mercury lamp (RW-LED-YT200gl, single exposure of 100 mj / cm 2 ), UV-LED light source irradiation (RW-UVAP202-20gl, single exposure is 1000mj / cm 2 ) The coating film was exposed at different wavelengths, its curing film formation was observed, and evaluated by finger touch method.

[0109] The evaluation criteria for the finger touch method are as follows: 1: Oily, not solid; 2: Oily on the surface, solidified at the bottom layer; 3: Sticky on the surface, with heavy fingerprints after touch; 4: Basically dry on the surface, slightly astringent after touch, with light fingerprints; 5: Completely solidified, smooth surface, and no fingerprints after touch.

[0110] The sensitivity test results of all embodiments and comparative examples of the present application are shown in Table 4.

[0111] Table 4

[0112]

[0113] (2) Yellowing resistance test

[0114] The photocurable composition was prepared by referring to the specific formula shown in Table 2. After the photocurable composition was stirred in a yellow light room, it was coated on tinplate using a 15# wire rod to form a coating with a wet film thickness of 10 μm. A 365nm-LED light source was used for exposure, receiving 2000mJ / cm 2 energy to fully cure it.

[0115] The yellowing test was performed using an X-Rite colorimeter, and the yellowing resistance of the photocurable resin was judged according to the △b value. The higher the △b value, the more obvious the yellowing and the worse the yellowing resistance. The yellowing resistance test results of all the examples and comparative examples of the present application are shown in Table 5.

[0116] Table 5

[0117]

[0118] It should be noted that the photocurable compositions in Comparative Examples 1 and 3 precipitated due to poor compatibility between the raw materials, and thus their yellowing resistance could not be evaluated.

[0119] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0120] (1) As can be seen from Table 2, the photoinitiator compound A used for comparison has poor solubility in PGMEA (only <5%), while the compounds 1 to 10 prepared in Examples 1 to 10 of this application all have good solubility in PGMEA (solubility > 15%), and all meet the requirement that the solubility of the photoinitiator should be greater than 8% by weight during industrial application. Considering their respective chemical structures, although the 7-position of fluorene in compound A is substituted by a triazine ring, the 4-position and 6-position on the triazine ring are not substituted by alkoxy groups, and its solubility is only <5%; while in the chemical structure of the photoinitiator compound C used for comparison, the triazine ring is not directly connected to the fluorene ring but is a substituent of the oxime ester structure, and its solubility is only <10%. By comparison, the solubilities of compound A and compound C are both worse than that of compound 1, which indicates that introducing the preferred types of substituents of this application at the 4-position and 6-position of the triazine ring is beneficial to improving the solubility of oxime ester fluorene-based photoinitiators.

[0121] (2) As can be seen from Table 3, the only difference between each example and the comparative example lies in the type of photoinitiator. Combining with Table 4, it can be seen that the photocurable compositions in Comparative Examples 1 and 3 are difficult to cure under the irradiation of a mercury lamp or an LED light source, and the curing efficiency is much lower than that of Examples 1 to 10; while the photocurable composition in Comparative Example 2 can only achieve basic surface drying under the irradiation of a mercury lamp or an LED light source and cannot be completely cured, and the curing effect is worse than that of Examples 1 to 10. It can be seen from this that the oxime ester fluorene-based photoinitiator with a specific structure provided in this application can be applied to a conventional ultraviolet curing system, and can achieve complete curing under the irradiation of both a mercury lamp and an LED light source, with good curing effects.

[0122] (3) As can be seen from Table 5, under the exposure of a 365nm - LED light source, the △b value of Comparative Example 2 is much higher than that of Examples 1 to 10, indicating that the yellowing resistance performance of Comparative Example 2 is much worse than that of Examples 1 to 10. That is, compared with the existing initiators with better photosensitivity (compounds A, B, and C in Comparative Examples 1 to 3), the photosensitive properties of compounds 1 to 10 are more excellent and they have the characteristic of being not easily yellowed. It can be seen from this that when the oxime ester fluorene-based photoinitiator with a specific structure provided in this application is applied to a photocurable composition, it can improve the curing efficiency under the irradiation of a light source, and has the characteristics of low yellowing and excellent solubility. At the same time, the above oxime ester fluorene-based photoinitiator can be used in a UV - LED photocuring system, especially as an initiator under the action of a 365nm light source, which can significantly improve the yellowing resistance performance.

[0123] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented, for example, in an order other than those described herein.

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An oxime ester fluorene-based photoinitiator for UV-LED photocuring system, characterized in that, The oxime ester fluorene-based photoinitiator contains a 4,6-alkoxy-substituted triazine ring group, and the oxime ester fluorene-based photoinitiator has a structure shown in the general formula (I): （I）， In the general formula (I), R1 and R1' are the same or different, and R1 and R1' are each independently selected from halogen, C1-C 10 alkyl, C4-C 10 aryl or C2-C 10 alkenyl, wherein the alkyl, the aryl, and the alkenyl may each be interrupted by O or N; or R1 and R1' may also be connected to form a ring; The R2 is selected from an alkyl group substituted by a C3-C8 cycloalkyl group, naphthyl, furyl, thienyl, phenyl, or a group obtained by substituting at least one hydrogen atom in the phenyl with a C1-C4 alkyl group; the R3 is selected from a straight-chain or branched-chain alkyl group having C1-C 10 and an alkyl group, phenyl, or a group obtained by substituting at least one hydrogen atom in the phenyl with a C1-C4 alkyl group; 10 ​ The R4 and the R5 are each independently selected from C1-C5 alkyl groups.

2. The oxime ester fluorene-based photoinitiator according to claim 1, characterized in that, The R1 and the R1' are selected from C1-C5 linear alkyl groups.

3. The oxime ester fluorene photoinitiator according to claim 2, characterized in that, The R1 and the R1' are selected from C1-C4 linear alkyl groups; the R2 is selected from phenyl, 1-naphthyl, α-furyl or α-thienyl; the R3 is selected from methyl, ethyl, phenyl or 2-methylphenyl; the R4 and the R5 are selected from C1-C4 linear or branched alkyl groups.

4. The oxime ester fluorene-based photoinitiator according to claim 1, wherein The oxime ester fluorene-based photoinitiator is selected from one or more of the following compounds 1 to compound 10: 。 5. A photocurable resin composition, characterized in that, The photocurable resin composition includes a photoinitiator, an alkali-soluble resin and a polymerizable monomer, wherein the photoinitiator comprises the oxime ester fluorene-based photoinitiator according to any one of claims 1 to 4.

6. The photocurable resin composition according to claim 5, characterized in that, The photocurable resin composition includes 0.5-10 parts of the oxime ester fluorene-based photoinitiator, 20-80 parts of the alkali-soluble resin and 20-80 parts of the polymerizable monomer.

7. The photocurable resin composition according to claim 6, wherein The photocurable resin composition further includes 0-200 parts of a solvent.

8. Use of the oxime ester fluorene-based photoinitiator according to any one of claims 1 to 4, or the photocurable resin composition according to any one of claims 5 to 7 in the field of photocuring.

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