o - allyl oxime ester - type photo - initiator compounds, their preparation methods and applications

Abstract

The present invention provides an o-allyl oxime ester-based photoinitiator compound, its preparation method and application. After the N-O single bond of such an oxime ester is broken under photoexcitation, the generated imine radical can further undergo intramolecular cyclization with the adjacent allyl group, and then substitution occurs to generate a 3,4-dihydroisoquinolinyl carbon-centered radical. The o-allyl oxime ester-based photoinitiator compound of the present invention, while generating corresponding high activity after photoexcitation decomposition, can further utilize the imine radical without initiating activity to form a carbon-centered radical with high initiating activity, further initiating polymerization, improving the comprehensive performance of the photoinitiator, overcoming the relatively low activity of the imine radical, having better photopolymerization rate and double bond conversion rate than the initiator without an adjacent allyl group when used in a photocuring formulation, thus having the advantages of high photolysis efficiency, good initiating performance, etc., and having a simple synthesis route and high yield, and having broad application prospects in the field of special photocuring.

Description

Technical Field

[0001] The present invention belongs to the fields of chemical synthesis and photocuring, and particularly relates to an o-allyloxime ester-based photoinitiator compound that can form highly active 3,4-dihydroisoquinolinyl carbon-centered radicals after photolysis, its preparation method, and its application in the field of photocuring, especially in free radical UV curing formulations. Background Art

[0002] Photoinitiator compounds in photopolymerization are an important class of fine organic chemical materials. They can undergo decomposition or hydrogen abstraction reactions under the excitation of light with appropriate wavelengths to generate active species, thereby initiating the polymerization of corresponding monomers. Generally speaking, they can be divided into free radical photoinitiators and cationic photoinitiators. These compounds generate free radical or cationic active species under the irradiation conditions of ultraviolet light or visible light, and are key species for inducing efficient photopolymerization reactions in unsaturated systems containing alkenes or epoxies. Therefore, they are an important component of radiation curing formulations.

[0003] Among the numerous commercially available photoinitiator products, oxime ester photoinitiators occupy a prominent position, especially in the field of photoresists for color photoresists. Its representative product, such as OXE-02 (the molecular structure is shown in the following figure), its molecular structure feature is that the carbonyl group reacts with hydroxylamine to form an oxime, and then reacts with an anhydride or acyl chloride to become an oxime ester. These molecules have good light absorption properties in the near ultraviolet region, and the photolysis rate is very fast. They are a class of free radical photoinitiators widely used in the fields of color photoresists, coatings, inks, etc., and are still a very high-end class of photoinitiators until now, especially widely used in the field of photocuring with high requirements for activity.

[0004]

[0005] Among them, OXE-02 will generate very highly active methyl radicals after photolysis, and the polymerization rate is very fast at the initial stage of initiating polymerization. However, another photolysis product, imine radical, is very inert and basically does not participate in the photopolymerization reaction. This is a shortcoming of this type of oxime ester. The photolysis mechanism of OXE-02 is shown in the following figure:

[0006]

[0007] If highly active photoinitiators can be developed through reasonable molecular design and specific research on photolysis mechanisms, especially by utilizing low-active imine radicals, it will be of great significance in the field of photocuring, and it is a key technical challenge problem faced by the current photocuring field.

[0008] In view of the above technical challenges, it is highly necessary to invent a class of photoinitiators that can enhance the activity of imine radicals generated by the photolysis of oxime esters. Additionally, the synthesis steps of such photoinitiators should have the advantages of simplicity, low cost, environmental friendliness during the synthesis process, and less waste in the three wastes. Such photoinitiators can be effectively compatible with free-radical curing resins and be compounded to form storage-stable photocurable inks or coatings, having a profound impact on fields such as green wood coating, environmental protection printing, inkjet printing, 3D printing, and energy-saving materials. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide a class of o-allyloxime ester photoinitiator compounds that can form highly active 3,4-dihydroisoquinolinyl carbon-centered radicals after photolysis. By utilizing the characteristic that the allyloxy group can rapidly undergo intramolecular cyclization with the imine radicals generated by the photolysis of oxime esters after photolysis, highly active carbon radicals are formed, thereby solving the technical problem that weak-active radicals in commercial photoinitiators in the prior art cannot initiate polymerization.

[0010] The second object of the present invention is to provide a preparation method for the above-mentioned o-allyloxime ester photoinitiator compounds.

[0011] The third object of the present invention is to provide the use of the above-mentioned o-allyloxime ester photoinitiator compounds in the fields related to photocuring.

[0012] To achieve the above objects, the solution of the present invention is as follows:

[0013] An o-allyloxime ester photoinitiator compound, wherein the allyl group is introduced to the ortho position of the oxime ester and can only be in the ortho position, so that an intramolecular cyclization reaction can occur after photolysis, and a compound that can form highly active 3,4-dihydroisoquinolinyl carbon-centered radicals after photolysis, and its molecular structure is shown in the general formula (I):

[0014]

[0015] Wherein,

[0016] R1, R2, and R3 are independently selected from a hydrogen atom, a halogen atom, CN, NO2, CF3, R, OR, SR, SOR, SO2R, NRR', where R and R' contain a straight-chain or branched-chain alkyl group with C1-C 24 or an aryl group with C6-C 24 In the structures of R and R', the hydrogen atoms are replaced by fluorine atoms to form a fluorocarbon chain structure. When R and R' exist simultaneously, they form a 3-6 membered ring system structure. One or more -CH2- in R and R' are independently replaced by -O-, -N-, -S-, -CO-, -COO-, -OCO- or a benzene ring;

[0017] R4 is selected from one or more of alkyl, alkenyl and benzyl, wherein one or more -CH2- may each independently be replaced by -O-, -N-, -S-, -CO-, -COO-, -OCO- or a benzene ring;

[0018] R5 and R6 are each independently selected from C1-C 20 linear alkyl, C1-C 20 branched alkyl, C3-C 12 cycloalkyl, heterocycloalkyl-containing, C6-C 12 benzene, alkylbenzene or more.

[0019] Preferably, the cycloalkyl is selected from wherein x = 1-5, y = 1-6.

[0020] Preferably, the heterocycloalkyl-containing is selected from wherein x = 1-5, y = 1-6, and z is selected from one or more of S, O, N.

[0021] Furthermore, the difference between the o-allyl oxime ester type photoinitiator compound of the present invention and the ordinary oxime ester type photoinitiator is that an allyl group is introduced at the ortho position of the oxime ester. After the N-O single bond of such an oxime ester is broken under photoexcitation, that is, after the oxime ester photolysis generates an imine radical without initiating activity and cannot be used to initiate photopolymerization. At this time, the allyl group introduced at the ortho position will first undergo intramolecular cyclization with the imine radical to form a highly active 3,4-dihydroisoquinolinyl carbon-centered radical, which can be used to initiate photopolymerization reaction, improving the photoinitiating efficiency of the oxime ester. The mechanism is as follows:

[0022]

[0023] A preparation method of an o-allyl oxime ester type photoinitiator compound as described above, which comprises the following steps:

[0024] (1) Dissolve m-hydroxybenzaldehyde (R5 is H) or m-hydroxybenzyl ketone (R5 is alkyl) substituted with R1, R2, R3 and allyl bromide in an organic solvent, and use a base as an acid-binding agent to reflux for an etherification reaction for 6-12 h to obtain intermediate (I)-a:

[0025]

[0026] (2) Under the protection of an inert gas, add intermediate (I)-a and anhydrous AlCl3 in equimolar amounts to a flask, add them to o-dichlorobenzene, heat to 180 °C, and keep warm for 3-6 h to obtain intermediate (I)-b:

[0027]

[0028] (3) Dissolve intermediate (I)-b and R4Br in an organic solvent, and use a base as an acid-binding agent to reflux for an etherification reaction for 12 - 24 h to obtain intermediate (I)-c:

[0029]

[0030] (4) Dissolve intermediate (I)-c in an ethanol solvent, and react with hydroxylamine hydrochloride at room temperature under sodium hydroxide for 12 - 24 h to obtain intermediate oxime product (I)-d:

[0031]

[0032] (5) Dissolve intermediate oxime product (I)-d and an acyl chloride or acid anhydride in an organic solvent, and react at room temperature under the action of a base for 12 - 24 h to obtain the target product (I) of the o-allyl oxime ester type photoinitiator compound:

[0033]

[0034] The overall preparation process is as follows:

[0035]

[0036] Furthermore, in steps (1), (3), and (5), the base is selected from one or more of triethylamine, potassium carbonate, sodium hydride, or sodium hydroxide.

[0037] Furthermore, in steps (1) and (3), the organic solvent is selected from one or more of acetone, ethanol, tetrahydrofuran, N,N-dimethylformamide, or N,N-dimethylacetamide.

[0038] Furthermore, in step (2), the inert gas is selected from nitrogen or argon, preferably nitrogen.

[0039] Furthermore, in step (5), the organic solvent is selected from one or more of chloroform, dichloromethane, or tetrahydrofuran.

[0040] Furthermore, this preparation method further includes subjecting the intermediates and the target product (I) obtained from the reactions of each step to conventional extraction and washing. The organic solvent used for extraction and washing is ethyl acetate or dichloromethane; the intermediates and the target product (I) can obtain pure products through recrystallization or column chromatography.

[0041] Application of an o-allyl oxime ester type photoinitiator compound as described above as a photoinitiator in a photocuring formulation system or as an intermediate, raw material, or reagent in chemical synthesis.

[0042] Furthermore, the photocuring formulation system comprises:

[0043] (1) Comprising at least one compound of general formula (I) as a photoinitiator or as one of the components of a photoinitiator system;

[0044] (2) Comprising at least one polymerizable compound containing an unsaturated double bond;

[0045] (3) Based on every 100 parts by weight of the total amount of polymerizable components in the system, the amount of the compound of general formula (I) is 0.5 - 10 parts by weight;

[0046] (4) Adding a small amount of auxiliaries, defoamers, leveling agents, dyes, and inorganic fillers to the formulation system where the initiator is located.

[0047] Furthermore, the polymerizable compound containing an unsaturated double bond is selected from one or more of methacrylate monomers and resins.

[0048] Furthermore, the methacrylate monomers are selected from one or more of monofunctional methyl methacrylate (MMA), bifunctional 1,6 - hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (TPGDA), trifunctional trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA). The resin also contains acrylate functional groups and is, for example, selected from one or more of polyurethane acrylate and silicone acrylate.

[0049] Furthermore, the auxiliaries are selected from one or more of acetone and dichloromethane.

[0050] Furthermore, the defoamer is a solvent - type defoamer BYK - 055.

[0051] Furthermore, the leveling agent is an organosilicon leveling agent BYK - 370.

[0052] Furthermore, the dyes are selected from one or more of titanium dioxide, zinc oxide, lithopone, carbon black, and graphite.

[0053] Furthermore, the inorganic fillers are selected from one or more of nano - silica and zirconia.

[0054] Some representative molecular structures of the present invention are as follows:

[0055]

[0056] Due to the adoption of the above - mentioned scheme, the beneficial effects of the present invention are:

[0057] (1) Advantages in terms of structure and performance: The o - allyl oxime ester - type photo - initiator compound of the present invention can form highly active 3,4 - dihydroisoquinolinyl carbon - centered radicals after photolysis. The imine radicals generated after the photolysis of the oxime ester moiety can undergo an intramolecular cyclization reaction with the allyl group in the ortho - position and only the ortho - position, thereby obtaining highly active 3,4 - dihydroisoquinolinyl carbon - centered radicals. On the one hand, this process overcomes the relatively low activity of imine radicals, and when used in a photocuring formulation, it has a better photopolymerization rate and double - bond conversion rate than initiators without an ortho - allyl group. This type of oxime ester has good sensitivity in the light - radiation range, thus having advantages such as high photolysis efficiency and good initiation performance.

[0058] (2) Advantages in terms of application: The o - allyl oxime ester - type photo - initiator compound of the present invention can form highly active carbon radicals after photolysis. For the application scenarios of photocuring formulations, it has the advantages of good solubility and good formulation stability; in addition, the raw materials in the preparation process are simple and easy to obtain, and the synthetic route is simple, facilitating preparation and large - scale production.

[0059] (3) Advantages in terms of actual application effect: The o - allyl oxime ester - type photo - initiator compound of the present invention can form highly active carbon radicals after photolysis. After being applied in a photocuring formulation, there are no imine - type derivatives that are commonly present after the photolysis of oxime ester compounds, showing excellent anti - yellowing advantages. Description of the Drawings

[0060] Figure 1 It is the general molecular - structure formula diagram of the o - allyl oxime ester - type photo - initiator compound of the present invention.

[0061] Figure 2 It is the 1 1H NMR spectrum of (I) - 3d in CDCl3 in Example 1 of the present invention.

[0062] Figure 3 It is the 1 1H NMR spectrum of (I) - 3 in CDCl3 in Example 1 of the present invention.

[0063] Figure 4 It is the 1 1H NMR spectrum of (I) - 4 in CDCl3 in Example 2 of the present invention.

[0064] Figure 5 It is the 1 1H NMR spectrum of (I) - 0 in CDCl3 in the comparative example of the present invention.

[0065] Figure 6 It is the ultraviolet - visible absorption spectrum diagram of the molecules of (I) - 3, (I) - 4 in the examples of the present invention, and (I) - 0 in the comparative example in an acetonitrile solution.

[0066] Figure 7 The kinetic curve of the thick film radical polymerization rate initiated by the molecules of (I)-3, (I)-4 in the embodiments of the present invention and (I)-0 in the comparative example under the excitation of a 254 nm LED light source.

[0067] Figure 8 The kinetic curve of the thick film radical polymerization rate initiated by the molecules of (I)-3, (I)-4 in the embodiments of the present invention and (I)-0 in the comparative example under the excitation of a 313 nm LED light source. Detailed implementation manners

[0068] The technical solutions of the present invention will be further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. These embodiments are implemented on the premise of the technical solutions of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0069] In the following embodiments, the experimental materials used can be purchased from conventional biochemical reagent companies without special instructions.

[0070] The technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0071] Example 1: To improve the solubility of the initiator, the synthesis of (I)-3 was first carried out by introducing a butyl group. The reaction route is as follows:

[0072]

[0073] Step (1): Dissolve 15.2 g of 4-methoxy-3-hydroxy-benzaldehyde and 13.2 g of allyl bromide in 150 mL of anhydrous ethanol, add 15.6 g of potassium carbonate, and under nitrogen protection and stirring, reflux for 10 h. Monitor by thin layer chromatography. After the raw materials are reacted, filter off the generated salt, evaporate acetone, extract the residue with dichloromethane solution, wash with saturated sodium chloride aqueous solution and water, and dry with anhydrous sodium sulfate, then evaporate all volatile components to obtain 18.7 g of intermediate (I)-3a. The purity analyzed by liquid chromatography is 97%, and the yield is 97.4%.

[0074] Step (2): 18.0 g of intermediate (I)-3a and 13.6 g of anhydrous aluminum trichloride were added to a 250 mL flask containing 100 mL of o-dichlorobenzene under nitrogen protection, heated to 180 °C in an oil bath, stirred for 3 h, cooled to room temperature, the product was dissolved with 1 mol / L dilute hydrochloric acid, extracted with dichloromethane, washed with saturated brine and deionized water, dried, the o-dichlorobenzene was removed by vacuum distillation after evaporation to dryness, and the remaining product was purified by column chromatography to obtain 16.4 g of intermediate (I)-3b, with a purity of 98.5% by liquid chromatography analysis and a yield of 91.5%.

[0075] Step (3): 16.0 g of intermediate (I)-3b and 11.5 g of n-butyl bromide were dissolved in 100 mL of anhydrous ethanol, then 15 g of anhydrous potassium carbonate was added, refluxed for 20 h under nitrogen protection and stirring, monitored by thin layer chromatography, after the raw materials reacted completely, the inorganic salts were filtered off, the ethanol was evaporated, dissolved with dichloromethane, washed with saturated sodium chloride aqueous solution and water, dried over anhydrous sodium sulfate and the solvent was evaporated to dryness to obtain 20.1 g of intermediate (I)-3c, with a purity of 96.7% by liquid chromatography analysis and a yield of 97.3%.

[0076] Step (4): 20.0 g of intermediate (I)-3c was dissolved in 100 g of anhydrous ethanol, cooled to 5 - 10 °C in an ice-water bath, 6.1 g of hydroxylamine hydrochloride and 3.55 g of sodium hydroxide were added, stirred for 1 h and then raised to room temperature, and stirred for another 20 h. The reaction system was poured into 300 mL of deionized water, the precipitate was filtered and washed with a large amount of water, and dried to obtain 18.6 g of intermediate (I)-3d as a white powder, with a purity of 98% by liquid chromatography analysis and a yield of 87.7%.

[0077] The specific NMR spectrum is shown in Figure 2 。

[0078] Step (5): 5.0 g of intermediate (I)-3d was placed in a single-necked flask, 2.8 g of triethylamine and 50 mL of anhydrous dichloromethane were added, the temperature was controlled to 0 - 5 °C in an ice-water bath, a solution of 3.0 g of acetic anhydride in 10 mL of dichloromethane was slowly added dropwise using a constant pressure dropping funnel, added dropwise in 0.5 h, stirred at low temperature for 2 h, then raised to room temperature and stirred for another 15 h. The dichloromethane was repeatedly washed and dried with water, evaporated to dryness, and purified by silica gel column chromatography to obtain 5.6 g of the target product (I)-3, with a purity of 99% by liquid chromatography analysis and a yield of 96.5%.

[0079] MS(C 17 H 23 O4): m / e: 305.16; Experimental result: 306.16 (M + H + )。

[0080] The specific NMR spectrum is shown in Figure 3 。

[0081] Example 2: Synthesis of (I)-4. The specific reaction route is as follows:

[0082]

[0083] For the specific steps, refer to Example 1. The difference is that the acetic anhydride in the last step of Step 1 is replaced with benzoyl chloride. Others are the same as in Example 1. The purity analyzed by liquid chromatography is 98.7%, and the yield is 97.5%.

[0084] MS(C 22 H 25 O4): m / e: 367.18; Experimental result: 368.18 (M + H + ).

[0085] For the specific NMR spectrum, see Figure 4 .

[0086] Comparative Example 1: To verify whether the introduction of allyl at the ortho position can effectively improve the photoinitiating efficiency, a comparative initiator without allyl at the ortho position was designed and prepared. The specific molecular structure is that after preparing (I)-a, no intramolecular isomerization reaction is carried out, and the allyl group is retained on the ether bond at the meta position. In this way, considering the photolysis mechanism, there will be no intramolecular cyclization reaction of the imine. The specific reaction route is as follows:

[0087]

[0088] For the specific steps, refer to Example 1. The difference is that the second step in Step 1 is omitted, that is, no rearrangement reaction needs to occur. Others are the same as in Example 1. Thus, meta-allyloxy oxime ester that cannot form carbon radicals is obtained as a comparative example. The purity analyzed by liquid chromatography is 97.6%, and the yield is 96.5%.

[0089] MS(C 18 H 23 O4): m / e: 249.27; Experimental result: 250.27 (M + H + ).

[0090] For the specific NMR spectrum, see Figure 5 .

[0091] <Experiment 1>

[0092] Test the UV-Vis absorption spectra and related photophysical parameters of the target products (I)-3, (I)-4 in the examples and (I)-0 in the comparative example.

[0093] Accurately weigh a certain amount of the samples in the examples and comparative examples, dissolve them in a volumetric flask, and then test the UV-Vis absorption spectra. The specific curve is as Figure 6As shown. The maximum absorption wavelength, the molar extinction coefficient at the maximum absorption wavelength, and the molar extinction coefficients at 254 nm and 313 nm are shown in Table 1. It shows that this type of molecule has good light absorption performance in the UVB and UVC ranges and is expected to be used in the field of photoinitiated polymerization in this wavelength band.

[0094] Table 1 Photophysical parameters of (I)-3, (I)-4 in the examples and (I)-0 in the comparative example in acetonitrile solution

[0095]

[0096] <Experiment 2>

[0097] Photocuring experiments of Examples (I)-3, (I)-4 and Comparative Example (I)-0 in the acrylate monomer-containing formulation under LED@254 nm and 313 nm light:

[0098] Prepare according to the following formulation (by weight percentage)

[0099] Trifunctional acrylate resin (trimethylolpropane triacrylate, TMPTA): 98%

[0100] Photoinitiator (I)-3 or (I)-4 or (I)-0: Three independent formulations, all 2%

[0101] Use Photo-DSC to test the photopolymerization kinetic curve of the formulation system under the excitation of 254 nm and 313 nm LED light sources, and calculate the conversion rate of acrylate according to the heat release. The specific curves are as Figure 7 and Figure 8 shown. It can be found from the two figures that the overall performance of (I)-3 with an acetyloxime ester is the best. Compared with (I)-4, the methyl radicals generated by it are more active than phenyl radicals; compared with Comparative Example (I)-0, although both generate methyl radicals, (I)-3 can utilize the cyclization of imine radicals to generate carbon radicals and shows the best photoinitiated polymerization ability at both wavelengths, manifested in a higher photoinitiated polymerization rate and a higher final double bond conversion rate.

[0102] <Experiment 3> Yellowing resistance test of photocuring formulation

[0103] Apply the ultraviolet curing coating on white tiles respectively, cure it completely under the same curing conditions, and after placing it in the sun for one week, the yellowing degree is not obvious (coating thickness 25 μm). After slow aging of the cured coating with a mercury lamp for 15 times, the Δb value is measured, and it is found that for the formulation of (I)-3, Δb < 3.

[0104] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

Claims

1. An o-allyl oxime ester type photoinitiator compound, characterized in that: Its molecular structure is shown in the general formula (I): Among them, R1 are all methoxy groups, and R2 and R3 are both H; R4 is methyl or butyl; R5 is H or methyl, and R6 is methyl, phenyl or vinyl; Or R4 is allyl; R5 is H, and R6 is methyl or phenyl.

2. The o-allyloxime ester photoinitiator compound according to claim 1, characterized in that: After the oxime ester is photolyzed, an imine radical without initiating activity is generated, which cannot be used to initiate photopolymerization. At this time, the allyl group introduced at the ortho position will first undergo intramolecular cyclization with the imine radical, thereby forming a 3,4-dihydroisoquinolinyl carbon-centered radical, which is used to initiate the photopolymerization reaction, improving the photoinitiating efficiency of the oxime ester. The mechanism is as follows: 。 3. A method for preparing an o-allyl oxime ester-based photoinitiator compound as described in claim 1 or 2, characterized in that: It includes the following steps: (1) Dissolve m-hydroxybenzaldehyde or m-hydroxyalkyl phenyl ketone substituted with R1, R2, and R3 and allyl bromide in an organic solvent, and use a base as an acid-binding agent to reflux for an etherification reaction for 6-12 h to obtain intermediate (I)-a: When m-hydroxybenzaldehyde and allyl bromide are dissolved in an organic solvent, R5 is H; when m-hydroxyalkyl phenyl ketone and allyl bromide are dissolved in an organic solvent, R5 is methyl; ； (2) Under the protection of an inert gas, add the intermediate (I)-a and anhydrous AlCl3 in equimolar amounts to a flask, add them to o-dichlorobenzene, heat to 180 °C, and keep warm for 3-6 h to obtain intermediate (I)-b: ； (3) Dissolve the intermediate (I)-b and R4Br in an organic solvent, and use a base as an acid-binding agent to reflux for an etherification reaction for 12-24 h to obtain intermediate (I)-c: ； (4) Dissolve the intermediate (I)-c in an ethanol solvent, and react with hydroxylamine hydrochloride at room temperature and under sodium hydroxide for 12-24 h to obtain intermediate oxime product (I)-d: ； (5) Dissolve the intermediate oxime product (I)-d and an acyl chloride or acid anhydride in an organic solvent, and react at room temperature under the action of a base for 12-24 h to obtain the target product (I) of the o-allyloxime ester type photoinitiator compound: 。 4. The preparation method according to claim 3, characterized in that: In steps (1), (3) and (5), the base is selected from one or more of triethylamine, potassium carbonate, sodium hydride or sodium hydroxide.

5. The preparation method according to claim 3, characterized in that: In steps (1) and (3), the organic solvent is selected from one or more of acetone, ethanol, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide.

6. The preparation method according to claim 3, characterized in that: In step (2), the inert gas is selected from nitrogen or argon.

7. The preparation method according to claim 3, characterized in that: In step (5), the organic solvent is selected from one or more of chloroform, dichloromethane, tetrahydrofuran.

8. The preparation method according to claim 3, characterized in that: This preparation method further includes extracting and washing the intermediates and the target product (I) obtained from the reactions of each step. The organic solvent used for extraction and washing is ethyl acetate or dichloromethane; the intermediates and the target product (I) can obtain pure products through recrystallization or column chromatography.

9. Use of an o-allyloxime ester type photoinitiator compound as described in claim 1 or 2 as a photoinitiator in a photocuring formulation system.

10. The application according to claim 9, wherein: The photocuring formulation system comprises: (1) Containing at least one compound as described in the general formula (I) as a photoinitiator or one of the photoinitiator components; (2) Containing at least one polymerizable compound containing an unsaturated double bond; (3) Based on every 100 parts by weight of the total amount of polymerizable components in the system, the amount of the compound of general formula (I) is 0.5 - 10 parts by weight; (4) Additives, defoamers, leveling agents, dyes, and inorganic fillers are added to the formulation system where the initiator is located; The additives are selected from one or more of acetone, dichloromethane, and defoamers; The defoamer is a solvent-based defoamer BYK-055; The leveling agent is an organosilicon leveling agent BYK-370; The dyes are selected from one or more of titanium dioxide, zinc oxide, lithopone, carbon black, and graphite; The inorganic fillers are selected from one or more of nano-silica and zirconia; 11. The application according to claim 10, characterized in that: The polymerizable compound containing an unsaturated double bond is selected from one or more of methacrylate monomers and resins; 12. The application according to claim 11, wherein: The methacrylate monomers are selected from one or more of methyl methacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate; 13. The application according to claim 11, wherein: The resins are selected from one or more of polyurethane acrylate and silicone resin acrylate.

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