Naphthenic oxime ester photoinitiator, its preparation method and application

Abstract

The application discloses a cycloalkane oxime ester photoinitiator and a preparation method and application thereof, and belongs to the field of chemical synthesis and photocuring technology. The photoinitiator has a structure as shown in the formula (I).

Description

Technical Field

[0001] This invention relates to the field of photoinitiator technology, specifically to a cycloalkane oxime ester photoinitiator, its preparation method, and its application. Background Technology

[0002] Photopolymerization technology, with its significant advantages such as energy saving, environmental protection, high efficiency, speed, and time-space controllability, is now widely used in traditional industrial fields such as coatings, inks, and adhesives, and is increasingly penetrating the manufacturing of high-tech products such as 3D printing. In photocurable resin formulations that include polymer monomers, reactive diluents, oligomers, and various additives, photoinitiators, although usually used in small quantities, are the core component of the photopolymerization system. Their performance directly determines not only the polymerization rate and reaction extent of the system, but also profoundly affects the final physicochemical properties of the cured product.

[0003] Oxime esters, as a class of highly efficient photoinitiators, have received widespread attention and research from academia and industry. Currently, commercially available products mainly include OXE-1 and OXE-2. The molecular structure of these initiators typically consists of two parts: a chromophore group and an oxime ester group. The chromophore group is often a highly conjugated π-bond structure, responsible for absorbing light energy and participating in energy conversion. Existing technologies often optimize the absorption band of the initiator by adjusting the conjugated structure. For example, patent CN201910215944.3 reports a long-conjugated carbazole-based oxime ester photoinitiator, which adjusts the absorption band and increases the absorption cross-section by extending the conjugated chain length at specific sites of the carbazole ring. The oxime ester group is the photolysis core, typically containing a C=N double bond and a weak NO bond. Under irradiation with a light source of a specific wavelength, the NO bond breaks, generating imine radicals and acyloxy radicals. Acyloxy radicals then undergo irreversible decarboxylation, producing carbon dioxide and active radicals. This process not only generates initiating active species, but the generated carbon dioxide also helps to inhibit oxygen inhibition polymerization. Furthermore, the irreversible reaction can effectively inhibit reverse electron transfer and reduce radical recombination.

[0004] Despite the aforementioned advantages of oxime ester photoinitiators, their initiation efficiency is still limited by the activity of the photolysis products. Among the two types of free radicals generated by NO bond cleavage, imine radicals are generally less active and thus difficult to participate effectively in the polymerization reaction. This means that for each photon absorbed by such initiators, only one effective active free radical is typically generated, which greatly limits their radical quantum yield and overall initiation efficiency.

[0005] To overcome this bottleneck, existing technologies have attempted to improve molecular structure design. For example, patent CN202110659660.0 reports a γ,δ-unsaturated oxime ester photoinitiator that utilizes an intramolecular cyclization reaction to convert low-activity imine radicals into highly active alkyl carbon radicals. However, further improving the radical quantum yield of oxime ester photoinitiators to achieve more efficient "one-photon dual-radical" initiation remains a key breakthrough for improving the performance of such initiators. Therefore, this invention proposes a novel solution based on a cycloalkane ring-opening mechanism to address the aforementioned technical problems. Summary of the Invention

[0006] To address the technical problem of low reactivity of imine radicals generated by the photolysis of existing oxime ester photoinitiators, which affects the initiation efficiency, this invention provides a cycloalkane oxime ester photoinitiator, its preparation method, and its applications. After the NO bond of the oxime ester photoinitiator molecule of this invention is broken, the generated imine radical containing a cycloalkane structure can further undergo an intramolecular ring-opening reaction, transforming into a highly reactive cyanoalkyl radical (carbon radical). Through this ring-opening mechanism, the photoinitiator of this invention can generate two highly reactive radicals by absorbing one photon, thereby overcoming the limitation of the quantum yield of reactive radicals in traditional oxime ester photoinitiators and significantly improving the photoinitiation efficiency.

[0007] To achieve the above objectives, the present invention provides a cycloalkane oxime ester photoinitiator having a chemical structure as shown in formula (I): Equation (Ⅰ), Wherein, R represents substituted or unsubstituted C1-C3 alkylene compounds, and C1-C3 alkylene compounds correspond to alkylene compounds containing 1 to 3 carbon atoms; R1 represents aromatic benzene rings, aromatic heterocyclic compounds and their various substituted derivatives.

[0008] Step (1): Synthesis of Intermediate C (Oxime Compound) Starting material A (cycloalkane ketone compound) and starting material B (hydroxylamine hydrochloride) are dispersed in an organic solvent in the presence of a catalyst to undergo an oxime reaction, yielding intermediate C. Starting material A is cyclobutanone, cyclopentanone, or cyclohexanone; the molar ratio of starting material A to starting material B is 1:1 to 1:5; the molar ratio of starting material A to catalyst is 1:2 to 1:10. The catalyst is selected from any one or a mixture of two or more of sodium bicarbonate, sodium carbonate, or sodium acetate. The temperature of this oxime reaction is controlled at 50-150℃, and the reaction time is 2-10 hours. The reaction equation is shown below:

[0009] Step (2): Synthesis of Intermediate F (acyl chloride compound): Starting material D (a carboxylic acid compound containing an R1 group) and starting material E (acyl chloride reagent) are dispersed in an organic solvent in the presence of catalyst N,N-dimethylformamide (DMF) to undergo an acyl chloride reaction, yielding intermediate F. The starting material E is selected from any one of thionyl chloride, phosphorus trichloride, phosphorus pentachloride, or oxalyl chloride; the molar ratio of starting material D to starting material E is 1:2 to 1:5; the molar ratio of starting material D to catalyst DMF is 1:2 to 1:15. The acyl chloride reaction is carried out at reflux temperature for 1-5 hours. The reaction equation is shown below:

[0010] Step (3): Synthesis of the open-ring oxime ester photoinitiator. Intermediate C obtained in step (1) and intermediate F obtained in step (2) are dispersed in an organic solvent in the presence of an acid-binding agent, and an esterification reaction is carried out to obtain the target product, the open-ring oxime ester photoinitiator. The molar ratio of intermediate C to intermediate F is 1:2 to 1:5; the molar ratio of intermediate C to the acid-binding agent is 1:2 to 1:15. The acid-binding agent is selected from any one or a mixture of two or more of triethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, or sodium hydride. The temperature of the esterification reaction is controlled at 10-100℃, and the reaction time is 3-8 hours. The reaction equation is shown below:

[0011] In steps (1) to (3) of the above preparation method, the organic solvent is independently selected from any one or more of dichloromethane, chloroform, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide or triethylamine.

[0012] The present invention further provides the application of the cycloalkane oxime ester compound represented by formula (I) as a photoinitiator in the preparation of photocurable compositions, photoresists, inks or 3D printing resins, especially as a photopolymerization initiator under ultraviolet or visible light irradiation.

[0013] By employing the above technical solution, the present invention has the following beneficial effects: (1) The cycloalkane oxime ester initiator molecule of the present invention connects the cycloalkane structure and the oxime ester group through chemical bonds. After the NO bond is photolytically broken, the formed cyclic imine radical transforms the originally low-initiating-activity imine radical into a highly-initiating-activity cyanoalkyl radical through an intramolecular ring-opening reaction. Therefore, this type of photoinitiator can generate two highly active radicals by absorbing one photon, and its active radical quantum yield and initiation efficiency are high.

[0014] (2) By changing the structure and type of the R1 group (aromatic ring part) in formula (I), the present invention can effectively control the absorption wavelength of the photoinitiator. This makes the initiator usable as an ultraviolet photoinitiator, and also as a visible light initiator by introducing a large conjugated system (such as pyrene), thus matching it with traditional high-pressure mercury lamps and energy-saving and environmentally friendly LED light sources, and has broad application prospects. Attached Figure Description

[0015] Figure 1 The UV-Vis absorption spectra of photoinitiators with different cycloalkane oxime ester structures in embodiments of the present invention are shown. This figure compares the effect of different aromatic ring structures (R1) on the absorption wavelength, demonstrating that the absorption range can be tuned by changing the chromophore structure.

[0016] Figure 2 The graph shows the real-time infrared double bond conversion rate of the acrylate system (TMPTA) cured using the photoinitiator of this invention in Example 11 of this invention. This graph demonstrates that the initiator of this invention has high photoinitiation efficiency.

[0017] Figure 3 The image shows a digital photograph of a polymer structure 3D printed using the photoinitiator in an embodiment of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise stated, the reagents and instruments used in the present invention are all commercially available conventional products.

[0019] Example 1: Preparation of Compound 1 (benzoylcyclobutanone oxime ester) (1) Intermediate: Synthesis of Cyclobutanone Oxime Cyclobutanone (1.4 g, 20 mmol), hydroxylamine hydrochloride (2.08 g, 30 mmol), and anhydrous sodium acetate (2.71 g, 33 mmol) as a catalyst were added to 30 mL of anhydrous ethanol and heated under reflux for 6 hours. After the reaction was complete, the mixture was extracted with dichloromethane (3 × 30 mL), and the organic layers were combined. The organic layers were washed with 20 mL of saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure (rotary evaporation) to obtain the crude product. The crude product was recrystallized from ethyl acetate to give 1.42 g of white crystals, yield: 83.8%. Structural Characterization: 1¹H NMR (400 MHz, Chloroform-d) δ 8.06 (s, 1H), 2.86 (dddd, J = 19.0, 9.5, 6.7, 1.4 Hz, 4H), 1.94 (p, J = 8.1 Hz, 2H). Reaction equation:

[0020] (2) Target product: Synthesis of compound 1 The prepared cyclobutanone oxime (0.42 g, 5 mmol), triethylamine (1.01 g, 10 mmol), and 20 mL of dichloromethane solvent were added to a two-necked flask. Benzoyl chloride (1.05 g, 7.5 mmol) was added dropwise under ice bath stirring. After the addition was complete, the mixture was allowed to return to room temperature for 6 hours. After the reaction was complete, 20 mL of deionized water was added to quench the reaction, and the mixture was extracted with dichloromethane (3 × 20 mL). The organic layers were combined. The organic layers were washed with 20 mL of saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure to remove the solvent and obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 5:1) to give 0.62 g of white solid, yield: 65.4%. Structural characterization: 1 ¹H NMR (400 MHz, Chloroform-d) δ 8.01 – 7.94 (m, 2H), 7.55 – 7.46 (m, 1H), 7.38 (t, J = 7.8 Hz, 2H), 3.07 (t, J = 8.1 Hz, 4H), 2.04 (q, J = 8.1 Hz, 2H). Reaction equation:

[0021] Example 2: Preparation of compound 2 (benzoylcyclopentanone oxime ester) Following the method described in Example 1, the starting materials were replaced with cyclopentanone oxime (0.99 g, 10 mmol) and benzoyl chloride (2.11 g, 15 mmol), and the amount of triethylamine as an acid-binding agent was (2.52 g, 25 mmol). After post-treatment and column chromatography (petroleum ether / ethyl acetate = 5:1), 1.48 g of white solid was obtained, yield: 73.1%.

[0022] Structural characterization: 1¹H NMR (400 MHz, Chloroform-d) δ 8.03 – 7.96 (m, 2H), 7.56 – 7.47 (m, 1H), 7.39 (t, J = 7.7 Hz, 2H), 2.68 – 2.60 (m, 2H), 2.60 – 2.53 (m, 2H), 1.79 (pd, J = 3.7, 1.8 Hz, 4H). Reaction equation:

[0023] Example 3: Preparation of compound 3 (benzoylcyclohexanone oxime ester) Following the method described in Example 1, the starting materials were replaced with cyclohexanone oxime (1.13 g, 10 mmol) and benzoyl chloride (1.82 g, 13 mmol), and the amount of triethylamine as an acid-binding agent was (2.02 g, 20 mmol). After post-treatment and column chromatography (petroleum ether / ethyl acetate = 5:1), 1.48 g of a white solid was obtained, yield: 69.7%. Structural characterization: 1 H NMR (400 MHz, Chloroform- d ) δ 8.06 – 7.96 (m, 2H), 7.56 – 7.47 (m, 1H), 7.39 (dd, J = 8.3, 7.1 Hz, 2H), 2.61 (t, J = 6.4 Hz, 2H), 2.44 – 2.37 (m, 2H), 1.79 – 1.55 (m, 6H). Reaction equation:

[0024] Example 4: Preparation of compound 4 (1-pyrenoylcyclobutanone oxime ester) (1) Intermediate: Synthesis of 1-pyrene carboxyl chloride Add 0.5 g (2 mmol) of 1-pyrene carboxylic acid, 1 mL of thionyl chloride, and 25 mL of dichloromethane to a two-necked flask. After stirring and mixing, add two drops of N,N-dimethylformamide (DMF) as a catalyst. Heat under reflux for 5 hours, then cool. Add more dichloromethane to the reaction mixture, and repeat rotary evaporation three times to remove excess thionyl chloride, yielding a yellow solid intermediate. Reaction equation:

[0025] (2) Target product: Synthesis of compound 4 The prepared 1-pyrenecarboxyl chloride (0.65 g, 2.5 mmol), triethylamine (0.3 g, 3 mmol), and 30 mL of dichloromethane solvent were added to a two-necked flask. Cyclobutanone oxime (0.2 g, 2.4 mmol) was added with stirring in an ice bath. The reaction was then carried out at room temperature for 6 hours. The mixture was quenched with 30 mL of deionized water, extracted with dichloromethane (3 × 20 mL), and the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The crude product was separated by silica gel column chromatography (petroleum ether / ethyl acetate = 5:1) to give 0.38 g of a yellow solid, yield: 51.3%. Structural characterization: 1 H NMR (400 MHz, DMSO- d 6) δ 8.98 (d, J = 9.4 Hz, 1H), 8.57 (d, J = 8.1 Hz, 1H), 8.49 – 8.34 (m, 5H), 8.29 (d, J =8.9 Hz, 1H), 8.19 (t, J = 7.6 Hz, 1H), 3.27 – 3.09 (m, 4H), 2.08 (p, J = 8.0Hz, 2H). Reaction equation:

[0026] Example 5: Preparation of compound 5 (1-pyrenoylcyclopentanone oxime ester) Following the method in Example 4, 1-pyrenecarboxyl chloride (0.32 g, 1.2 mmol) was reacted with cyclopentanone oxime (0.18 g, 1.8 mmol). After post-treatment and column chromatography, 0.22 g of a yellow solid was obtained, yield: 55.3%. Structural characterization: 1 H NMR (400 MHz, DMSO- d 6) δ 9.01 (d, J = 9.4 Hz, 1H), 8.60 (d, J = 8.1 Hz,1H), 8.47 – 8.34 (m, 5H), 8.28 (d, J = 8.9 Hz, 1H), 8.18 (t, J = 7.6 Hz, 1H), 2.79 – 2.55 (m, 4H), 1.81 (qd, J = 6.7, 6.1, 4.4 Hz, 4H).

[0027] Example 6: Preparation of compound 6 (1-pyrenoylcyclohexanone oxime ester) Following the method in Example 4, 1-pyrenecarboxyl chloride (0.32 g, 1.2 mmol) was reacted with cyclohexanone oxime (0.2 g, 1.8 mmol). After post-treatment and column chromatography, 0.19 g of a yellow solid was obtained, yield: 48.2%. Structural characterization: 1 H NMR (400 MHz, Chloroform- d ) δ 9.09 (d, J = 9.4 Hz, 1H), 8.49 (d, J = 8.1Hz, 1H), 8.25 – 8.14 (m, 3H), 8.14 – 8.06 (m, 2H), 8.06 – 7.94 (m, 2H), 2.73 – 2.58 (m, 2H), 2.55 – 2.43 (m, 2H), 1.79 (dd, J = 7.9, 4.2 Hz, 2H), 1.70 (p, J = 6.6, 6.0 Hz, 2H), 1.65 – 1.58 (m, 2H).

[0028] Example 7: Preparation of compound 7 (4-benzoylbenzoylcyclobutanone oxime ester) (1) Intermediate: Synthesis of 4-benzoylbenzoyl chloride Add 1.47 g (6 mmol) of 4-benzoylbenzoic acid, 3.2 mL of thionyl chloride, and 25 mL of dichloromethane to a two-necked flask, and add two drops of DMF as a catalyst. Reflux the reaction for 5 h, cool, and repeatedly remove the thionyl chloride by rotary evaporation to obtain a yellow solid.

[0029] Reaction equation:

[0030] (2) Target product: Synthesis of compound 7 4-Benzoylbenzoyl chloride (0.24 g, 0.8 mmol), triethylamine (0.2 g, 2 mmol), and 30 mL of dichloromethane solvent were mixed, and cyclobutanone oxime (0.08 g, 1 mmol) was added under ice bath conditions. The reaction was carried out at room temperature for 6 hours. After post-treatment and column chromatography (petroleum ether / ethyl acetate = 5:1), 0.13 g of a pale yellow solid was given, yield: 56.2%. Structural characterization: 1H NMR (400 MHz, Chloroform- d ) δ 8.12 – 8.04 (m, 2H), 7.82 – 7.70 (m, 4H), 7.60 –7.51 (m, 1H), 7.49 – 7.39 (m, 2H), 3.14 – 3.05 (m, 4H), 2.07 (p, J = 8.1 Hz, 2H). Reaction equation:

[0031] Example 8: Preparation of compound 8 (4-benzoylbenzoylcyclopentanone oxime ester) Following the method of Example 7, cyclopentanone oxime (0.1 g, 1 mmol) was used instead of cyclobutanone oxime. After post-processing and column chromatography, 0.15 g of pale yellow solid was obtained, yield: 63.7%.

[0032] Structural characterization: 1 H NMR (400 MHz, Chloroform- d ) δ 8.14 – 8.05 (m, 2H), 7.83 – 7.69 (m,4H), 7.60 – 7.51 (m, 1H), 7.49 – 7.39 (m, 2H), 2.72 – 2.54 (m, 4H), 1.81(dtq, J = 5.5, 3.8, 1.7 Hz, 4H). Reaction equation:

[0033] Example 9: Preparation of compound 9 (4-benzoylbenzoylcyclohexanone oxime ester) Following the method of Example 7, cyclohexanone oxime (0.22 g, 2 mmol) was used instead of cyclobutanone oxime, and the amount of acyl chloride was adjusted accordingly. After post-processing and column chromatography, 0.26 g of a pale yellow solid was obtained, with a yield of 66.2%. Structural characterization: 1 H NMR (400MHz, Chloroform- d ) δ 8.13 – 8.07 (m, 2H), 7.82 – 7.77 (m, 2H), 7.77 – 7.71(m, 2H), 7.62 – 7.51 (m, 1H), 7.43 (dd, J = 8.3, 7.0 Hz, 2H), 2.62 (t, J=6.4 Hz, 2H), 2.46 – 2.38 (m, 2H), 1.72 (ddd, J = 21.9, 8.0, 4.1 Hz (4H), 1.63–1.58 (m, 2H). Reaction equation:

[0034] Example 10: Preparation of compound 10 (4-chlorobenzoylcyclobutanone oxime ester) Following the method described in Example 1, benzoyl chloride was replaced with 4-chlorobenzoyl chloride and reacted with cyclobutanone oxime. The reaction was then followed by post-treatment and column chromatography separation.

[0035]

[0036] Example 11: Preparation of compound 11 (4-benzoylbenzoyl-4-oxacyclohexanone oxime ester) Following the method described in Example 7, dihydro-2H-pyran-4(3H)-ketooxime was used instead of cyclobutanone oxime, and the amount of acyl chloride was adjusted accordingly. The mixture was then post-processed and separated by column chromatography.

[0037]

[0038] Example 12: Preparation of compound 12 (4-nitrobenzoylcyclobutanone oxime ester) Following the method described in Example 2, benzoyl chloride was replaced with 4-nitrobenzoyl chloride and reacted with cyclopentanone oxime. The reaction was then followed by post-treatment and column chromatography separation.

[0039]

[0040] Example 13: Determination of the absorption performance of cycloalkane oxime ester photoinitiators The UV-Vis absorption properties of compounds 1-9 prepared in the examples were measured. A UV-Vis spectrophotometer was used to scan in the range of 200-800 nm.

[0041] Experimental results are as follows Figure 1 As shown, compounds with different R1 groups (such as compounds 4 and 7) are compared in detail. The test results demonstrate that the absorption wavelength of photoinitiators can be significantly modulated by changing the structure and conjugation degree of aromatic compounds (R1). In particular, compounds incorporating large conjugated systems such as pyrene groups exhibit a significant red shift in their absorption band, making them well-matched with traditional high-pressure mercury lamps and energy-saving and environmentally friendly LED light sources (such as 365nm, 385nm, and 405nm), thus demonstrating broad applicability.

[0042] Example 14: Photoinitiation efficiency test To verify the initiation activity of the photoinitiator of this invention, the following tests were conducted: Under light-protected conditions, 5 mg of the photoinitiator of this invention (compounds 4, 8 and 9 respectively) was added to 1 g of trimethylolpropane triacrylate (TMPTA) monomer and stirred thoroughly until completely dissolved to obtain the photopolymerization sample to be tested.

[0043] The conversion rate of the characteristic peak of acrylate double bond (C=C) in the sample was monitored by real-time infrared spectroscopy (RT-FTIR) under high-pressure mercury lamp irradiation with a light intensity of 10 mW / cm².

[0044] Figure 2 The real-time curves showing the double bond conversion rate of the samples over time are presented. The results show that the cycloalkane oxime ester photoinitiator of this invention can achieve a high double bond conversion rate (>40%) in a very short time. This confirms that the cyclic imine radicals generated by the photolysis of this type of initiator do indeed undergo an effective intramolecular ring-opening reaction, transforming into highly reactive carbon radicals to initiate polymerization. The photolysis mechanism of the cycloalkane oxime ester photoinitiator is shown in the figure below:

[0045] Example 15: Application of cycloalkane photoinitiators in 3D printing Trimethylolpropane triacrylate (TMPTA) and 1,6-hexanediol diacrylate (HDDA) were mixed in a 1:1 mass ratio. Compound 8 of Example 8, comprising 1 wt% of the total mass of the mixture, was added, and the mixture was stirred and sonicated until compound 8 was completely dissolved to obtain a photocurable material for 3D printing. This material was then added to a printer to print the target 3D model. Figure 3 As shown, the cycloalkane oxime ester initiator of the present invention can print good three-dimensional structures in 3D printing.

Claims

1. A cycloalkane oxime ester photoinitiator, characterized in that, It has the chemical structure shown in formula (Ⅰ): Wherein: R represents a substituted or unsubstituted C1-C3 alkylene group; R1 represents an aromatic benzene ring, an aromatic heterocyclic compound, and its substituted derivatives.

2. The cycloalkane oxime ester photoinitiator according to claim 1, characterized in that, Any -CH2- in R is selected from unsubstituted groups or groups substituted by O, S, or S=O, and the hydrogen on the group can be replaced by a halogen.

3. The cycloalkane oxime ester photoinitiator according to claim 1, characterized in that, The aromatic benzene ring, aromatic heterocyclic compound and its substituted derivative in R1 are selected from one of the following groups: phenyl, pyrene, or benzoylphenyl; any H in R1 is selected from an unsubstituted group or a group substituted by a halogen, phenyl, nitro, sulfonic acid, cyano, ether or thioether group.

4. A method for preparing the cycloalkane oxime ester photoinitiator according to any one of claims 1-3, characterized in that, Includes the following steps: a. Oxime reaction: Cycloalkanone compounds are reacted with hydroxylamine hydrochloride in an organic solvent in the presence of a catalyst to obtain an intermediate product with structural formula (II); Formula (II) b. Acyl chloride reaction: A carboxylic acid compound containing an R1 group is reacted with an acyl chloride reagent in an organic solvent in the presence of a catalyst to obtain an intermediate product with structural formula (Ⅲ); #imgpt2# Formula (III) c. Esterification reaction: The intermediate product obtained in step a and the intermediate product obtained in step b are reacted in an organic solvent under the action of a catalyst / acid-binding agent to obtain the cycloalkane oxime ester photoinitiator as shown in formula (I).

5. The preparation method according to claim 4, characterized in that, In step a: the cycloalkane ketone compound is selected from cyclobutanone, cyclopentanone, or cyclohexanone; the molar ratio of the cycloalkane ketone compound to hydroxylamine hydrochloride is 1:1 to 1:5; the molar ratio of the cycloalkane ketone compound to the catalyst is 1:2 to 1:10; the catalyst is selected from one or more of sodium bicarbonate, sodium carbonate, or sodium acetate; and the reaction temperature is 50-150℃.

6. The preparation method according to claim 4, characterized in that, In step b: the molar ratio of the carboxylic acid compound containing R1 to the acyl chloride reagent is 1:2 to 1:5; the molar ratio of the carboxylic acid compound containing R1 to the catalyst is 1:2 to 1:15; the acyl chloride reagent is selected from one of thionyl chloride, phosphorus trichloride, phosphorus pentachloride or oxalyl chloride; the catalyst is N,N-dimethylformamide (DMF); the reaction temperature is the reflux temperature.

7. The preparation method according to claim 4, characterized in that, In step c: the molar ratio of the intermediate product obtained in step a to the intermediate product obtained in step b is 1:2 to 1:5; the molar ratio of the intermediate product obtained in step a to the catalyst / acid-binding agent in step c is 1:2 to 1:15; the catalyst / acid-binding agent is selected from one or more of triethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, or sodium hydride; the reaction temperature is 10-100℃.

8. The preparation method according to any one of claims 4-7, characterized in that, The organic solvent mentioned in step ac is independently selected from one or more of dichloromethane, chloroform, methanol, ethanol, toluene, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, or triethylamine.

9. The use of the cycloalkane oxime photoinitiator according to any one of claims 1-3 in the preparation of photocurable compositions, photoresists, inks or 3D printing resins.

10. The application according to claim 9, characterized in that, The application is a photopolymerization initiation application under ultraviolet or visible light irradiation.

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