Modified oxime ester type photoinitiator and preparation method thereof

Abstract

The invention provides a modified oxime ester type photoinitiator and a preparation method thereof, and the modified oxime ester type photoinitiator is obtained by taking an acridone compound as an initial raw material, performing Friedel-Crafts acylation and nitrosation, and esterifying with aromatic acyl halide. Aryl in the acridone compound is substituted with strong electron donating groups such as alkyl and / or alkoxy, the strong electron donating groups, carbon-oxygen double bonds substituted on aromatic acyl halide, the alkyl and / or alkoxy form D-pi-A-pi-D structures on the two sides of an oxime ester group, and a large conjugated system and a strong intramolecular electron transfer characteristic exist. The maximum absorption wavelength of the modified oxime ester type photoinitiator has remarkable red shift, the modified oxime ester type photoinitiator has high sensitivity to the emission wavelength of a commercial LED light source, and the stability and the photosensitive activity of the modified oxime ester type photoinitiator are greatly improved; in addition, secondary amino contained in the acridone compound is used as a hydrogen donor, so that the photopolymerization initiation rate and the monomer conversion rate of the modified oxime ester photoinitiator in a system are relatively high.

Description

Technical Field

[0001] The present invention relates to the field of photoinitiators, and particularly to a modified oxime ester type photoinitiator and a preparation method thereof. Background Art

[0002] The photocuring technology is a means of using the energy of ultraviolet light or visible light to cause photoinitiator molecules to generate active species such as free radicals or cations, and initiate the corresponding free radical or cationic polymerization to form polymer materials. Among them, a crucial step is the absorption of light by the photoinitiator. After absorbing light energy, the photoinitiator generates active species through direct photolysis, or undergoes electron or proton transfer with a co-initiator to generate active species. According to the different active species generated during the initiation process, it can be divided into free radical type photoinitiators (Type I that can be photolyzed, such as 1173, 369, TPO, and hydrogen abstraction Type II, such as BP, ITX) and cationic type photoinitiators (iodonium salts and sulfonium salts). Among the free radical type photoinitiators, those such as 1173 and 369 have poor absorption capacity for the emission wavelengths (365 - 405 nm) of commercial LED light sources, and only a small amount of photoinitiators, such as TPO, can have good absorption in the LED range. Among the cationic type photoinitiators, onium salt compounds have good photosensitivity and photoreaction activity, and are increasingly used in the cationic photopolymerization of alicyclic epoxy resins; in addition, they will generate free radicals first during the photolysis process and are also very effective photoinitiators in initiating free radical polymerization.

[0003] Oxime ester compounds are considered to be a class of highly efficient cleavage type photoinitiators, and have the advantages of simple synthesis route and good thermal stability. However, in the production of color photoresist in LCD display color filters, high-coloring formulations are often used, and high-coloring formulations require that the photoinitiator in the photoresist formulation used has good photosensitivity and sufficient penetration curing ability to achieve deep curing of the colored system. Currently, commercial oxime esters and onium salts still cannot be well matched with the emission spectrum of LEDs and cannot achieve good penetration curing ability. Therefore, in order to meet the requirements of some special working conditions, it is necessary to red-shift their absorption wavelengths and improve the sensitivity to LED light sources. Summary of the Invention

[0004] In order to improve the sensitivity of the oxime ester type photoinitiator to LED light sources and increase its photoinitiating activity, the present invention provides an LED-sensitive modified oxime ester type photoinitiator and a preparation method thereof.

[0005] An LED-sensitive modified oxime ester type photoinitiator has the structure shown in Formula I:

[0006]

[0007] In Formula I, R1, R2, R3, R4, R5, R6, and R7 are each independently an alkyl group, an alkoxy group, or a hydrogen atom having 1 to 2 carbon atoms, and R 13 is an alkyl group having 1 to 11 carbon atoms, Ar is a phenyl group substituted with at least one group selected from an alkyl group, an alkoxy group, a phenyl group, and a hydrogen atom having 1 to 4 carbon atoms, and n = 1 or 2.

[0008] In the exploration stage, the inventors found that when an acridone structure is introduced into an oxime ester-based photoinitiator, the photosensitivity of the photoinitiator increases, but the maximum light absorption wavelength does not show an obvious red shift. In order to increase the maximum light absorption wavelength of the oxime ester-based photoinitiator to adapt to the wavelength range of commercial LED light sources and at the same time have good photo-polymerization initiation efficiency, the inventors introduced an aromatic hydrocarbon substituted with an alkyl group and / or an alkoxy group on the other side of the oxime ester group. As a result, a D-π-A-π-D structure can be formed in the resulting modified oxime ester-based photoinitiator molecule by means of the ester group, increasing the intramolecular electron transfer rate. Moreover, since the secondary amino group in the acridone compound can act as a hydrogen donor to provide hydrogen ions for the photo-polymerization reaction, the photo-polymerization initiation rate and monomer conversion rate of the modified oxime ester-based photoinitiator in the system are improved.

[0009] In some embodiments of the present invention, the modified oxime ester-based photoinitiator is prepared by using an acridone compound having a structure of Formula II as a raw material, subjecting it to Friedel-Crafts acylation and nitrosation, and then performing an esterification reaction with an aromatic acyl halide having a structure of Formula III:

[0010]

[0011]

[0012] In Formula II, R'1, R'2, R'3, R'4, R'5, R'6, and R'7 are each independently an alkyl group, an alkoxy group, or a hydrogen atom having 1 to 2 carbon atoms, and are specifically selected to be correspondingly consistent with R1 to R7 in Formula I; in Formula III, R8, R9, R 10 、R 11 、R 12 are each independently an alkyl group, an alkoxy group, a phenyl group, or a hydrogen atom having 1 to 4 carbon atoms, and X is chlorine, bromine, or iodine.

[0013] In some embodiments of the present invention, the acridone compound is preferably one of acridone (CAS: 578-95-0), 1,4-dimethoxy-9(10H)-acridone (CAS: 25379-15-1), N,N'-dimethylquinacridone (CAS: 19205-19-7), 5,12-dihydro-2-methyl-quinolin-[2,3-B]acridine-7,14-dione (CAS: 10228-01-0), and 2,9-dimethylquinacridone (CAS: 980-26-7). Because the substrate of the Friedel-Crafts acylation reaction requires an electron-rich aromatic ring, that is, an aromatic ring substituted with an electron-donating group, and the steric hindrance effect of the substituent that may exist in the reaction system, in the present invention, the inventors selected the above-mentioned acridone compounds with an alkyl or alkoxy group with a carbon number of not more than 2 as a substituent as the substrate for preparing the modified oxime ester photoinitiator, thereby obtaining a better yield and product purity.

[0014] In some embodiments of the present invention, the aromatic acyl halide is preferably one of benzoyl chloride, 2,3-dimethylbenzoyl chloride, 2,4-dimethylbenzoyl chloride, 3,4-dimethylbenzoyl chloride, 2,6-dimethylbenzoyl chloride, 2,4,6-trimethylbenzoyl chloride, m-methoxybenzoyl chloride, p-methoxybenzoyl chloride, 2,5-dimethoxybenzoyl chloride, 4-ethoxybenzoyl chloride, 4-propylbenzoyl chloride, 4-isopropylbenzoyl chloride, 2-tert-butylbenzoyl chloride and biphenyl-4-carbonyl chloride.

[0015] Because when the modified oxime ester type photoinitiator is prepared in the present invention, the final esterification reaction occurs by utilizing the aromatic acyl halide and the hydroxyl group on the carbon-nitrogen double bond, and the aromatic acyl halide is used to introduce a benzene ring electron-withdrawing benzene ring or a substituted benzene ring structure on one side of the oxime ester group. With the change of the substituent on the benzene ring, the inventors found that the alkyl or alkoxy group with a carbon number of 1-4 has an enhancing effect on the electron-donating effect of the benzene ring, and the electron-donating effect of the biphenyl structure is also greater than the electron-donating effect of a single benzene ring. The D-π-A-π-D structural effect of the group in the structure significantly improves the photopolymerization initiation rate and monomer conversion rate of the modified oxime ester type photoinitiator. Therefore, preferably, in the present invention, when preparing the modified oxime ester type photoinitiator, the aromatic acyl halide used is selected from one of the above-mentioned compounds.

[0016] In some embodiments of the present invention, the method for preparing the modified oxime ester type photoinitiator comprises the following steps:

[0017] S1: After performing Boc protection treatment on the acridone compound, the solvent used in the Boc protection treatment is removed and the mixture is set aside for use;

[0018] S2: Dissolve the product obtained in S1 and catalyst 1 in organic solvent 1, then dropwise add alkyl acyl halide while stirring, control the system temperature at -5 - 5 °C, after the addition is completed, keep the temperature for reaction for 5 - 6 h, pour the reaction system into an acid solution for hydrolysis and water washing, after removing the solvent by reduced pressure concentration, add an ether solvent, cool to -10 - -5 °C, and recrystallize the product obtained by filtration by adding the ether solvent again;

[0019] S3: Add the product obtained in S2 and catalyst 2 into organic solvent 2, stir evenly, control the system temperature at -2 - 5 °C, dropwise add alkyl nitrite, after the addition is completed, keep the temperature for reaction for 4 - 5 h, after removing the solvent by reduced pressure concentration, adjust the pH to neutral, add an ether solvent, cool and filter, and then recrystallize by adding the ether solvent again;

[0020] S4: Add the product obtained in S3 and catalyst 3 into organic solvent 3, stir evenly, control the system temperature at 10 - 18 °C, dropwise add aromatic acyl halide, keep the temperature for reaction for 1 - 1.5 h, adjust the pH to acidic, separate and remove the inorganic layer, wash the organic layer with water until neutral, evaporate and concentrate to remove the solvent, and then recrystallize by adding an ether solvent;

[0021] S5: Remove the Boc group from the product obtained in S4, and the modified oxime ester type photoinitiator is obtained.

[0022] In some embodiments of the present invention, when preparing the modified oxime ester type photoinitiator, since an acridone compound is used as a raw material, the secondary amino group contained therein is extremely likely to undergo an acylation reaction with subsequent acyl halide reagents. Therefore, in order to protect the secondary amino group, it is protected with a Boc group before the reaction. Preferably, the protection condition is carried out with Boc2O / N,N - dimethylformamide (DMF) / triethylamine (TEA) at 40 - 50 °C, and the Boc removal treatment is carried out with a n - butyllithium (BuLi) / tetrahydrofuran (THF) system.

[0023] The reaction principles of the above - mentioned reactions are shown in Formulas 1, 2, 3, 4, and 5:

[0024]

[0025]

[0026] In some embodiments of the present invention, when preparing the modified oxime ester type photoinitiator, in S2, catalyst 1 is at least one of anhydrous aluminum trichloride, anhydrous zinc chloride, anhydrous iron trichloride, and anhydrous iron tetrachloride; in S3, catalyst 2 is at least one of hydrochloric acid at 35 - 40 wt%, phosphoric acid, and sulfuric acid at 30 - 60 wt%; in S4, catalyst 3 is at least one of 4 - dimethylaminopyridine and triethylamine.

[0027] In some embodiments of the present invention, when preparing the modified oxime ester type photoinitiator, in S2, the organic solvent 1 is at least one of benzene, toluene, and xylene; in S3, the organic solvent 2 is at least one of methanol, ethanol, propanol, methyl ethyl ketone, acetone, dioxane, and tetrahydrofuran; in S4, the organic solvent 3 is at least one of dichloromethane, chloroform, bromoethane, and carbon tetrachloride.

[0028] In some embodiments of the present invention, when preparing the modified oxime ester type photoinitiator, in S2, the alkyl acyl halide is at least one of propionyl chloride, n-butyryl chloride, valeryl chloride, hexanoyl chloride, octanoyl chloride, nonanoyl chloride, decanoyl chloride, and lauroyl chloride; in S3, the alkyl nitrite is at least one of n-propyl nitrite, n-butyl nitrite, isobutyl nitrite, isoamyl nitrite, and n-hexyl nitrite.

[0029] In the experimental stage, the inventors found that when preparing the modified oxime ester type photoinitiator, the longer the alkyl chain length of the alkyl acyl halide used, the better its photoinitiated polymerization ability. However, when the number of carbon atoms in the alkyl chain exceeds 12, more reaction time is required to obtain a better reaction yield. Considering cost reduction, in the present invention, the alkyl carbon number of the alkyl acyl halide is 1-12.

[0030] In some embodiments of the present invention, during Friedel-Crafts acylation, the molar ratio of the acridone compound after Boc protection to the alkyl acyl halide is 1:1.05-1.20, and the dosage of catalyst 1 is 17-20% of the total mass of the S2 reaction system.

[0031] In some embodiments of the present invention, during nitrosation, the molar ratio of the product obtained in S2 to the alkyl nitrite is 0.65-0.80:1.

[0032] In some embodiments of the present invention, during acylation esterification, the molar ratio of the product obtained in S3 to the aromatic acyl halide is 1:1.10-1.25.

[0033] Beneficial effects: Compared with the prior art, the present invention innovatively uses acridone compounds as substrates to prepare photoinitiators. An oxime ester group with an aryl group is introduced onto the benzene ring of the acridone compound through acylation esterification to obtain a modified oxime ester type photoinitiator: an aromatic ring substituted with an alkoxy group or an alkyl group in the acridone compound serves as an electron-donating group, and the carbon-oxygen double bond serves as an electron-withdrawing group. The two coexist in the modified oxime ester type photoinitiator to form a D-π-A-π-D structure, resulting in an obvious red shift in its maximum light absorption wavelength and an increase in the sensitivity to LED light, thereby obtaining better stability and photosensitive activity; in addition, the acridone compound contains a secondary amino group as a hydrogen donor, making the photoinitiated polymerization rate and monomer conversion rate of the modified oxime ester type photoinitiator in the system relatively high. Detailed Embodiments

[0034] The present invention will be further described in detail below in conjunction with examples. It should be noted that the following examples and comparative examples are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0035] The raw materials and their masses used in Examples 1 - 3 are shown in detail in Table 1:

[0036] Table 1 Raw materials and their corresponding added masses used in Examples 1 - 3

[0037]

[0038]

[0039] The preparation process of the modified oxime ester type photoinitiator described in Example 1 is illustrated as follows:

[0040] Example 1

[0041] S1: Acridone (CAS: 578 - 95 - 0) was subjected to Boc group protection treatment with N,N - dimethylformamide (DMF) as the solvent and triethylamine (TEA) as the catalyst at 40 °C, and then DMF was removed by evaporation for later use;

[0042] S2: 62.2 g (0.2 mol) of the product obtained in S1 and 60 g of aluminum trichloride were dissolved in 200 ml of benzene, and then 19.43 g (0.21 mol) of propionyl chloride was added dropwise with stirring, controlling the system temperature at -5 - 5 °C. After the addition was completed, the reaction was carried out under heat preservation for 5 h. The reaction system was poured into dilute hydrochloric acid for hydrolysis and washing. After removing the solvent by reduced pressure concentration, petroleum ether was added, and it was cooled to -5 °C. The product obtained by filtration was recrystallized again with petroleum ether and dried to obtain 50.4 g of product I, with a yield of 41.9%; 1 1H - NMR(CDCl3, 500 MHz): δ1.656~1.681(3H, t, -CH3), 2.872~2.901(2H, d, -CH2-), 7.518(H, s, acridone), 7.375(H, s, acridone), 8.296(H, s, acridone), 1.116~1.133(9H, m, tert - butyl), 8.304(H, s, acridone), 7.368(H, s, acridone), 6.885(H, s, acridone), 7.514(H, s, acridone), MS(m / z): 365[M + 1] + ;

[0043] S3: Add 35.3 g (0.1 mol) of product I-1 and 95 ml of 35 wt% hydrochloric acid to 200 ml of tetrahydrofuran, stir evenly, control the system temperature at -2 - 5 °C, dropwise add 13.7 g (0.15 mol) of n-propyl nitrite. After the addition is complete, keep the reaction at a constant temperature for 4 h. After concentrating under reduced pressure to remove the solvent, adjust the pH to neutral, add petroleum ether. After cooling and filtering, add petroleum ether again for recrystallization, and dry to obtain 23.5 g of product II, with a yield of 48.0%; 1 H-NMR(CDCl3, 500 MHz): δ1.645~1.670(3H, t, -CH3), 7.515(H, s, acridone), 7.361(H, s, acridone), 8.271(H, s, acridone), 1.114~1.131(9H, m, tert-butyl), 8.254(H, s, acridone), 7.345(H, s, acridone), 6.851(H, s, acridone), 7.483(H, s, acridone), 8.175(H, s, hydroxime), MS(m / z): 394[M + 1] + ;

[0044] S4: Add 19.1 g (0.5 mol) of product II-1 and 8.5 g of 4-dimethylaminopyridine to 200 ml of dichloromethane, stir evenly, control the system temperature at 10 - 18 °C, dropwise add 77.3 g (0.55 mol) of benzoyl chloride, keep the reaction at a constant temperature for 1 h, adjust the pH to acidic, separate and remove the inorganic layer, wash the organic layer with water until neutral, evaporate and concentrate to remove the solvent, then add petroleum ether for recrystallization, and dry to obtain 75.2 g of product III-1, with a yield of 78.0%; 1 H-NMR(CDCl3, 500 MHz): δ1.621~1.648(3H, t, -CH3), 7.212~7.220(2H, m, benzene ring), 7.415~7.428(3H, m, benzene ring), 7.723(H, s, acridone), 7.512(H, s, acridone), 8.537(H, s, acridone), 1.116~1.135(9H, m, tert-butyl), 8.423(H, s, acridone), 7.492(H, s, acridone), 6.871(H, s, acridone), 7.503(H, s, acridone), MS(m / z): 498[M + 1] + ;

[0045] S5: Under the action of n-butyllithium, use tetrahydrofuran as the solvent to remove the Boc group from the product obtained in S4, and the modified oxime ester type photoinitiator-1 is obtained. 11H-NMR (CDCl3, 500 MHz): δ 1.621 - 1.648 (3H, t, -CH3), 7.212 - 7.220 (2H, m, benzene ring), 7.415 - 7.428 (3H, m, benzene ring), 7.723 (1H, s, acridone), 7.512 (1H, s, acridone), 8.537 (1H, s, acridone), 4.012 (1H, s, acridone), 8.423 (1H, s, acridone), 7.492 (1H, s, acridone), 6.871 (1H, s, acridone), 7.503 (1H, s, acridone), MS (m / z): 398 [M+1] + 。

[0046] The preparation processes of Examples 2 and 3 are the same as that of Example 1, except that the raw materials used are selected and added according to Table 1. Among them, the molar amounts of Product I-2 (the product of S2 in Example 2) and I-3 (the product of S2 in Example 3) participating in the reaction with S3 are both 0.2 mol, and the molar amounts of Product II-2 (the product of S3 in Example 2) and II-3 (the product of S3 in Example 3) participating in the reaction with S4 are both 0.5 mol. The reaction conditions can be varied within a suitable range.

[0047] Comparative Example 1

[0048] The operation is the same as that of Example 1, except that the benzoyl chloride used in S4 is replaced with acetyl chloride.

[0049] Comparative Example 2

[0050] The commercially available photoinitiator is OXE-01 purchased from Jiangxi Luote Chemical Industry.

[0051] Performance Test

[0052] Light absorption performance: The photoinitiators obtained in the above examples and comparative examples were dissolved in anhydrous acetonitrile to prepare a solution with a concentration of 3×10 -5 mol / L. The ultraviolet absorption in the 320 - 420 nm band was measured using a UV-5200 (PC) ultraviolet-visible spectrophotometer from Shanghai Yuanxi Instruments. According to the ultraviolet absorption, the corresponding molar extinction coefficient was calculated using the Lambert-Beer law A = ∈×c×L, where A represents the absorbance of the measured solution, c (mol / L) represents the concentration of the solution, L is the thickness of the sample cell (the thickness of the sample cell used in the test L = 1 cm), and ε is the molar extinction coefficient of the solution;

[0053] Photopolymerization initiation rate: In the monomer TPGDA, a photoinitiator accounting for 1 wt% of the total monomer amount was added. Then, the solution was stirred for 10 min in the dark to make it evenly mixed. A small hole with a diameter of 2 mm was punched on a silicone mold with a thickness of 0.3 mm using a hole puncher as the mold. The mold was placed on a pre-cleaned glass slide and pressed firmly, and the previously prepared photosensitive liquid was dropped into the mold to form a liquid film with a diameter of 2 mm and a thickness of 0.3 mm. A cover glass was placed on the liquid film to ensure an anaerobic condition. Subsequently, under the irradiation of a point light source at 410 nm (light intensity: 200 mW / cm), the change in the characteristic absorption peak area of the double bond group near 6167 cm -1 was monitored by Fourier transform near-infrared spectroscopy, and the change curve of the double bond conversion rate of the system with the irradiation time was obtained by calculation. The calculation formula for the double bond conversion rate is as follows:

[0054]

[0055] where ηdouble bond is the double bond conversion rate (%), S t is the characteristic peak area of the double bond group corresponding to the irradiation time t, and S0 is the characteristic peak area of the double bond group corresponding to t = 0.

[0056] The molar extinction coefficients of the photoinitiators described in the above examples and comparative examples are shown in Table 2-1:

[0057] Table 2-1 Physical parameters of light absorption of photoinitiators in Examples 1-3 and Comparative Examples 1-2 in anhydrous acetonitrile

[0058]

[0059]

[0060] From the data in Table 2-1, it can be seen that the maximum absorption wavelength of the oxime ester type photoinitiator prepared in Comparative Example 1 is 380 nm, and the maximum absorption wavelength of the commercial oxime ester type photoinitiator OXE-01 in Comparative Example 2 is 325 nm. By comparison, the maximum absorption wavelength of the modified oxime ester type photoinitiator provided by the present invention is near 410 nm. Compared with the photoinitiators in Comparative Examples 1-2, the light absorption wavelength has an obvious red shift; and the maximum molar extinction coefficients of the modified oxime ester type photoinitiators in Examples 1-3 are not less than 45000 L / mol·cm, indicating that they have strong light absorption ability and high photosensitive activity.

[0061] The test results of the photopolymerization initiation rate of the photoinitiators described in the above examples and comparative examples are shown in Table 2-2:

[0062] Table 2-1 Double bond conversion rates of photopolymerization initiation of photoinitiators described in Examples 1-3 and Comparative Examples 1-2

[0063] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 <![CDATA[η 10min > 52.1％ 56.8％ 54.3％ 48.5％ 16.7％ <![CDATA[η 20min > 63.5％ 65.2％ 61.8％ 59.2％ 25.6％ <![CDATA[η 30min > 69.6％ 74.2％ 72.9％ 62.2％ 33.3％ <![CDATA[η 40min > 71.9％ 78.1％ 80.1％ 69.4％ 40.7％ <![CDATA[η 50min > 72.3％ 81.6％ 84.7％ 71.6％ 44.9％ <![CDATA[η 60min > 72.5％ 81.9％ 85.2％ 72.1％ 45.3％

[0064] As can be seen from Table 2-2, the modified oxime ester type photoinitiator described in the present invention shows a relatively high monomer conversion rate at the initial stage of the free radical polymerization system, and can reach the highest conversion rate in about 60 minutes of light irradiation, and its highest conversion rate is not less than 70%, indicating that the modified oxime ester type photoinitiator has a relatively high photo-polymerization initiation rate and monomer conversion rate. By comparing the data of Comparative Example 1, it can be seen that in Comparative Example 1, since the aromatic acyl halide used in S4 was replaced with an alkyl acyl halide, the electron-withdrawing effect on the right side of the oxime ester group in the obtained modified oxime ester type photoinitiator was insufficient, resulting in a relatively low photo-polymerization initiation rate and monomer conversion rate finally obtained. By performing photo-polymerization tests on commercial oxime ester type photoinitiators (Comparative Example 2), it can be seen that the modified oxime ester type photoinitiator provided by the present invention has a faster photo-polymerization initiation rate than the existing photoinitiator OXE-01.

[0065] In summary, the modified oxime ester type photoinitiator provided by the present invention has good light absorption ability at about 410 nm and good sensitivity to LED light sources. At the same time, in the free radical polymerization system, it has a photo-polymerization initiation rate and monomer conversion rate superior to those of the prior art, and has good application prospects in the field of LED-sensitive photoinitiators.

Claims

1. A modified oxime ester type photoinitiator, characterized in that, It has the structure shown in Formula I: ; wherein, R1, R2, R3, R4, R5, R6, and R7 are each independently an alkyl group, an alkoxy group, or a hydrogen atom having 1 to 2 carbon atoms; R 13 is an alkyl group having 1 to 11 carbon atoms; Ar is a phenyl group substituted with at least one group selected from an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a phenyl group, and a hydrogen atom; n = 1 or 2.

2. The modified oxime ester type photoinitiator according to claim 1, wherein, Using acridone compounds with the structure of Formula II as raw materials, after Friedel-Crafts acylation and nitrosation, an esterification reaction is carried out with aromatic acyl halides having the structure of Formula III to obtain: , ; wherein, in formula II, R'1, R'2, R'3, R'4, R'5, R'6, and R'7 are each independently an alkyl group, an alkoxy group, or a hydrogen atom having 1 to 2 carbon atoms, and the specific selection is correspondingly consistent with that of R1 to R7 in formula I; in formula III, R8, R9, R 10 , R 11 , and R 12 are each independently an alkyl group, an alkoxy group, a phenyl group, or a hydrogen atom having 1 to 4 carbon atoms; X is chlorine, bromine, or iodine.

3. The modified oxime ester type photoinitiator according to claim 2, characterized in that, The acridone compounds are one of acridone, 1,4-dimethoxy-9(10H)-acridone, N,N'-dimethylquinacridone, 5,12-dihydro-2-methyl-quinoline[2,3-b]acridine-7,14-dione, 2,9-dimethylquinacridone.

4. The modified oxime ester type photoinitiator according to claim 1, wherein The aromatic acyl halides are one of benzoyl chloride, 2,3-dimethylbenzoyl chloride, 2,4-dimethylbenzoyl chloride, 3,4-dimethylbenzoyl chloride, 2,6-dimethylbenzoyl chloride, 2,4,6-trimethylbenzoyl chloride, m-methoxybenzoyl chloride, p-methoxybenzoyl chloride, 2,5-dimethoxybenzoyl chloride, 4-ethoxybenzoyl chloride, 4-propylbenzoyl chloride, 4-isopropylbenzoyl chloride, 2-tert-butylbenzoyl chloride, biphenyl-4-carbonyl chloride.

5. A method for preparing the modified oxime ester type photoinitiator according to any one of claims 1-4, characterized in that, It includes the following steps: S1: After carrying out Boc protection treatment on the acridone compound, remove the solvent used in the Boc protection treatment and set it aside for use; S2: Dissolve the product obtained in S1 and catalyst 1 in organic solvent 1, then dropwise add alkyl acyl halide while stirring, control the system temperature at -5 - 5°C, after the dropping is completed, keep the reaction for 5 - 6 h, pour the reaction system into an acid solution for hydrolysis and water washing, remove the solvent by reduced pressure concentration, add an ether solvent, cool to -10 - -5°C, and recrystallize the product obtained by filtration by adding the ether solvent again; S3: Add the product obtained in S2 and catalyst 2 to organic solvent 2, stir evenly, control the system temperature at -2 - 5°C, dropwise add alkyl nitrite, after the dropping is completed, keep the reaction for 4 - 5 h, remove the solvent by reduced pressure concentration, adjust the pH to neutral, add an ether solvent, cool and filter, and then recrystallize by adding the ether solvent again; S4: Add the product obtained in S3 and catalyst 3 to organic solvent 3, stir evenly, control the system temperature at 10 - 18°C, dropwise add aromatic acyl halide, keep the reaction for 1 - 1.5 h, adjust the pH to acidic, separate and remove the inorganic layer, wash the organic layer to neutral, evaporate and concentrate to remove the solvent, and then recrystallize by adding an ether solvent; S5: Carry out the removal of the Boc group on the product obtained in S4 to obtain the modified oxime ester type photoinitiator.

6. The preparation method of the modified oxime ester type photoinitiator according to claim 5, characterized in that, In S2, catalyst 1 is at least one of anhydrous aluminum trichloride, anhydrous zinc chloride, anhydrous iron trichloride, and anhydrous iron tetrachloride; in S3, catalyst 2 is at least one of 35 - 40 wt% hydrochloric acid, phosphoric acid, and 30 - 60 wt% sulfuric acid; in S4, catalyst 3 is at least one of 4-dimethylaminopyridine and triethylamine.

7. The preparation method of the modified oxime ester type photoinitiator according to claim 4, characterized in that, In S2, the alkyl acyl halide is at least one of propionyl chloride, n-butyryl chloride, valeryl chloride, hexanoyl chloride, octanoyl chloride, nonanoyl chloride, decanoyl chloride, and lauroyl chloride; in S3, the alkyl nitrite is at least one of n-propyl nitrite, n-butyl nitrite, isobutyl nitrite, isoamyl nitrite, and n-hexyl nitrite.

8. The preparation method of the modified oxime ester type photoinitiator according to claim 3, characterized in that, In S2, the molar ratio of the product obtained in S1 to the alkyl acyl halide added is 1:1.05 - 1.20, and the dosage of catalyst 1 is 17 - 20% of the total mass of the S2 reaction system.

9. The preparation method of the modified oxime ester type photoinitiator according to claim 3, characterized in that, In S3, the molar ratio of the product obtained in S2 to the alkyl nitrite added is 0.65 - 0.80:

1.

10. The preparation method of the modified oxime ester type photoinitiator according to claim 3, characterized in that, In S4, the molar ratio of the product obtained in S3 to the aromatic acyl halide added is 1:1.10 - 1.25.

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