Cationic Photoinitiator Intermediate and Its Preparation Method, Water-Soluble Cationic Photoinitiator and Its Preparation Method

Abstract

The present invention discloses a cationic photoinitiator intermediate and a preparation method thereof. The molecular structure of the cationic photoinitiator intermediate is shown in Formula 3: The present invention also discloses a cationic photoinitiator obtained by the above-mentioned cationic photoinitiator intermediate. The molecular structure thereof is shown in Formula Y. By targeted design of the molecular structure of the cationic photoinitiator, its solubility, photoinitiation efficiency and safety in an aqueous system are significantly improved. The cationic photoinitiator prepared by the present invention can exist stably in environmentally friendly solvents such as water and ethanol, solving the problem of cationic photoinitiators being sensitive to water, avoiding the occurrence of inhibition effect, and also showing good photoinitiation efficiency. At the same time, its molecular structure can copolymerize with monomers in a photoinitiated polymerization reaction, and achieve covalent bonding to the polymer main chain after curing, thereby effectively avoiding the migration problem of the photoinitiator. The present invention also discloses a preparation method of the cationic photoinitiator.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoinitiators, and in particular relates to a cationic photoinitiator intermediate and a preparation method thereof. The present invention also relates to a water-soluble cationic photoinitiator and a preparation method thereof. Background Art

[0002] Due to its advantages of rapid processing, energy saving, and environmental friendliness, photocuring technology has been widely used in coatings, inks, adhesives, electronic materials, and 3D printing. Traditional photocuring systems are typically based on environmentally unfriendly organic solvents and utilize photoinitiators to activate the crosslinking reaction between monomers and oligomers.

[0003] The main photoinitiators currently used in the market can be divided into two categories: free radical and cationic. Typical cationic photoinitiators are sulfonium salt initiators, which can generate proton acids through ultraviolet light irradiation, initiating the polymerization of systems such as epoxy and vinyl ether. Although cationic photoinitiators exhibit excellent initiation ability in the presence of oxygen, they still have the following shortcomings:

[0004] 1. Cationic photoinitiators have poor solubility in many environmentally friendly solvents, especially in low-toxic environmentally friendly solvents such as alcohols. They are difficult to dissolve completely, resulting in low photocuring efficiency and even inability to achieve uniform dispersion, affecting the curing efficiency and the performance of the final product. This makes it difficult for traditional photoinitiators to meet increasingly stringent environmental regulations.

[0005] 2. Sensitivity to water: Traditional sulfonium salt cationic photoinitiators are very sensitive to water because the nucleophilicity of water molecules will destroy the cationic chain reaction in the initiation system, which can easily lead to the inhibition of the photopolymerization process, the so-called "inhibition" effect. Therefore, the use of such initiators in water-based photocuring systems usually requires an extremely strict water-free environment, which increases the complexity and cost of the photocuring process.

[0006] 3. Migration issues: Traditional photoinitiators only act as initiators during the polymerization reaction and do not participate in the final polymerization network. Therefore, they are in a free state in the cured material, causing the photoinitiator molecules to easily migrate to the surface of the material, resulting in a decrease in the physical and chemical properties of the cured material. In addition, the migrated photoinitiators may also pollute the environment or cause harm to human health, especially in sensitive areas such as food packaging and medical devices, where there are significant safety risks.

[0007] 4. VOC emission problem: Traditional organic solvent photocuring systems usually require a large amount of non-environmentally friendly organic solvents. These solvents will evaporate during use and drying, generating volatile organic compound (VOC) emissions, causing air pollution and increasing the environmental burden. Therefore, the development of photoinitiators that can be dissolved in environmentally friendly solvents to reduce VOC emissions has become an important research direction in the field of photocuring. Summary of the Invention

[0008] In response to the problems in the related art, the present invention proposes a cationic photoinitiator intermediate and a preparation method thereof. The present invention also discloses a cationic photoinitiator and a preparation method thereof using the cationic photoinitiator intermediate. By improving the molecular structure of an aryl formylmethylsulfonium salt and introducing an imidazole group as an ionic liquid functional group, the solubility of the photoinitiator of the present invention in an environmentally friendly solvent is significantly improved, so that the photoinitiator can be evenly dispersed in the solution, thereby ensuring efficient initiation of photocuring; at the same time, by introducing a hydrocarbon group containing a double bond into the photoinitiator structure, the photoinitiator not only initiates polymerization during the polymerization process of the component system, but can also participate in the cross-linking reaction itself, thereby effectively reducing the migration risk after curing and improving the stability and safety of the final product, thereby overcoming the above-mentioned technical problems existing in the existing related art.

[0009] The technical solution of the present invention is achieved as follows:

[0010] A cationic photoinitiator intermediate, whose molecular structure is shown in Formula 3:

[0011]

[0012] Wherein, R1 and R2 are independently alkyl, cyano, aryl, substituted aryl, benzyl, substituted benzyl or oligoether groups, that is, R1 and R2 can be the same or different.

[0013] Preferably, the alkyl group is C n H m , wherein n and m are independently a natural number less than 30; the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0014] Preferably, the cationic photoinitiator intermediate is one of the following formulas 1-3 to 8-3:

[0015]

[0016] The preparation method of the above cationic photoinitiator intermediate comprises at least the following steps:

[0017] 1) Compound B-1 is dissolved in an organic solvent, cooled to 0-5°C, and phosgene and aluminum chloride as catalysts are slowly added, with the molar ratio of compound B-1 to phosgene B-2 being 1:1-1.5. The mixture is stirred for 3-5 hours, and then the reaction mixture is poured into ice water for neutralization. Intermediate B-3 is obtained by liquid-liquid extraction, drying, and rotary evaporation.

[0018]

[0019] 2) Dissolve the intermediate B-3 in an organic solvent, add N-bromosuccinimide and benzoyl peroxide, the molar ratio of intermediate B-3 to N-bromosuccinimide being 1:1-1.5, and stir for 1-3 hours at a system temperature of ≤0°C. Then, warm to room temperature and continue stirring for 3-5 hours. After the reaction, neutralize with sodium carbonate and perform liquid-liquid extraction to obtain intermediate B-4, the structure of which is shown in Formula B-4:

[0020]

[0021] 3) Intermediate B-4 is dissolved in an organic solvent, and dialkyl sulfide R1SR2 and potassium hexafluoroantimonate are added. The molar ratio of intermediate B-4, dialkyl sulfide R1SR2 and potassium hexafluoroantimonate is 1:1-1.5:1-1.5. The reaction is stirred at room temperature for 7-9 hours, and then poured into ice water to precipitate a solid. The solid is filtered, washed and dried to obtain intermediate 2, whose molecular structure is shown in Figure 2:

[0022]

[0023] Wherein, R1 and R2 are independently alkyl, cyano, aryl, substituted aryl, benzyl, substituted benzyl or oligoether groups, that is, R1 and R2 can be the same or different.

[0024] Preferably, the alkyl group is C n H m , wherein n and m are independently a natural number less than 30; the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0025] 4) Intermediate 2 is dissolved in an organic solvent, cooled to ≤0°C, and boron tribromide is slowly added dropwise at a molar ratio of intermediate 2 to boron tribromide of 1:1-1.5. The mixture is stirred for 0.5-1.5 hours, then warmed to room temperature and stirred for 5-7 hours. After the reaction, the mixture is poured into ice water for neutralization, and liquid-liquid extraction, drying, and recrystallization are performed to obtain cationic photoinitiator intermediate 3, whose molecular structure is shown in 3:

[0026]

[0027] Wherein, R1 and R2 are independently alkyl, cyano, aryl, substituted aryl, benzyl, substituted benzyl or oligoether groups, that is, R1 and R2 can be the same or different.

[0028] Preferably, the alkyl group is C n H m , wherein n and m are independently a natural number less than 30; the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0029] A water-soluble cationic photoinitiator, whose molecular structure is shown in Formula Y:

[0030]

[0031] Where R is * is the link position, n is a natural number greater than 1 and less than 30;

[0032] R1 and R2 are independently an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group, that is, R1 and R2 may be the same or different.

[0033] Preferably, the alkyl group is C n H m , where n and m are independently natural numbers less than 30.

[0034] Preferably, the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0035] The cationic photoinitiator of the present invention is a water-soluble cationic photoinitiator.

[0036] Preferably, the molecular structure of the water-soluble cationic photoinitiator is one of the following formulas Y-1 to Y-16:

[0037]

[0038] The preparation method of the water-soluble cationic photoinitiator comprises at least the following steps:

[0039] 1) preparing the above-mentioned cationic photoinitiator intermediate 3;

[0040] 2) Dissolving the cationic photoinitiator intermediate 3 in an organic solvent, and then adding an imidazole derivative, wherein the molar ratio of the cationic photoinitiator intermediate 3 to the imidazole derivative is 1:1-1.5, heating the system temperature to 75-85°C, stirring the reaction for 11-13 hours, and after cooling, removing the organic solvent by rotary evaporation, washing, and recrystallizing to obtain a water-soluble cationic photoinitiator Y.

[0041] Preferably, in step 2), the molecular structure of the imidazole derivative is as shown in 4:

[0042]

[0043] Beneficial effects of the present invention:

[0044] A cationic photoinitiator with ionic liquid properties is formed by combining an aryl formylmethylsulfonium salt derivative with a specific imidazole group through a multi-step reaction, thereby ensuring that the cationic photoinitiator of the present invention can be efficiently initiated. Moreover, by introducing the imidazole group into the molecular structure, the cationic photoinitiator of the present invention can be stably present in environmentally friendly solvents such as water and ethanol, thereby solving the problem of cationic photoinitiators being sensitive to water, avoiding the occurrence of the inhibition effect, simplifying the operating conditions, and reducing the cost of the curing system.

[0045] Through reasonable molecular design, a hydrocarbon group containing a double bond is introduced, so that the photoinitiator of the present invention can participate in the polymerization process while initiating the polymerization reaction, forming a covalently bound polymer network structure, thereby effectively reducing the migration of the initiator and meeting application scenarios with strict requirements on product safety.

[0046] Through a specific structural design, the present invention achieves comprehensive optimization of the cationic photoinitiator in terms of solubility, initiation efficiency and mobility, which can effectively improve the curing rate and product performance. It can be applied to cationic polymerization photocuring systems such as vinyl ether, and is particularly suitable for fields such as food packaging and medical coatings, meeting the requirements of low mobility and high initiation efficiency. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] Example 1

[0049] The synthetic route of this embodiment is shown in the figure below:

[0050]

[0051] 1) Preparation of intermediate B-3

[0052] 1.1) In a dry three-necked flask, weigh 196 g of compound B-1 (1 mol), add an appropriate amount of anhydrous toluene as solvent, stir under nitrogen protection, and slowly add 92.5 g of compound B-2 (1 mol) and an appropriate amount of aluminum chloride as a catalyst.

[0053] 1.2) React at room temperature for 4 h, stirring continuously during the reaction.

[0054] 1.3) After the reaction, the reaction mixture was poured into ice water for neutralization to generate a solid. The solid was collected by filtration and repeatedly washed with deionized water until the filtrate was neutral. The resulting crude product was recrystallized from ethanol to obtain 183.34 g of intermediate B-3 with a yield of 89%. The H NMR spectrum data were as follows:

[0055] 1 H NMR (500MHz, Chloroform) δ8.43–7.83 (m, 3H), 7.11 (dd, J = 7.5, 1.4Hz, 1H), 3.81 (s, 3H), 2.50 (s, 3H).

[0056] 2) Preparation of intermediate B-4

[0057] 2.1) In a dry three-necked flask, weigh 154.5 g of compound B-3 (0.75 mol), add an appropriate amount of anhydrous tetrahydrofuran (THF) as a solvent, stir at room temperature, and slowly add 133.5 g of N-bromosuccinimide (NBS, 0.75 mol) and an appropriate amount of benzoyl peroxide as a free radical initiator.

[0058] 2.2) The reaction system was heated to 70°C and maintained for 6 h to ensure complete bromination reaction.

[0059] 2.3) After the reaction, the reaction mixture was cooled to room temperature, the by-product of bromosuccinimide was filtered off, and the filtrate was collected; the solvent was removed by rotary evaporation, and the resulting crude product was recrystallized from ethanol to obtain 181.7 g of intermediate B-4 with a yield of 85%. The H NMR spectrum data were as follows:

[0060] 1 H NMR (500MHz, Chloroform) δ8.32–8.14(m,2H),8.03(d,J=3.1Hz,1H),7.11(dd,J=15.0,2.9Hz,1H),4.83(s,2H),3.81(s,3H).

[0061] Example 2

[0062] The synthetic route of this embodiment is shown in the figure below:

[0063]

[0064] 3) Preparation of intermediate 1-2

[0065] 3.1) In a dry three-necked flask, weigh 142.5 g of compound B-4 (0.5 mol) prepared in Example 1, add 31 g of dimethyl sulfide (1-1, 0.5 mol), and add 137 g of potassium hexafluoroantimonate (KSbF6, 0.5 mol) as a reaction reagent. Add an appropriate amount of butanone to the flask as a solvent and stir under nitrogen protection.

[0066] 3.2) The reaction system was heated to reflux temperature and maintained at reflux for 8 h to facilitate the complete reaction.

[0067] 3.3) After the reaction was completed, the reaction mixture was cooled to room temperature, filtered to remove insoluble matter, and the filtrate was collected. The solvent was removed by rotary evaporation, and the resulting crude product was recrystallized from ethanol to obtain 203.9 g of intermediate 1-2, with a yield of 81% and a molecular weight of 501.95 as determined by MS.

[0068] 4) Preparation of cationic photoinitiator intermediates 1-3

[0069] 4.1) In a dry three-necked flask, weigh 125.25 g of compound 1-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Under nitrogen, stir slowly and add 62.6 g of boron tribromide (BBr3, 0.25 mol). The reaction system is gradually warmed to room temperature and the reaction is maintained for 6 h to ensure complete removal of the methoxy group.

[0070] 4.2) After the reaction, ice water was slowly added to the system to terminate the reaction and neutralize the generated byproduct HBr; the reaction mixture was subjected to liquid-liquid extraction, and the organic phase was collected; after drying, the solvent was removed by rotary evaporation, and the crude product was recrystallized from ethanol to obtain 106.09 g of cationic photoinitiator intermediate 1-3, with a yield of 87% and a molecular weight of 487.93 as determined by MS.

[0071] Example 3

[0072] The synthetic route of this embodiment is shown in the figure below:

[0073]

[0074] 3) Preparation of intermediate 2-2

[0075] 3.1) In a dry three-necked flask, weigh 142 g (0.5 mol) of the intermediate B-4 prepared in Example 1, add an appropriate amount of anhydrous butanone as a solvent, and stir under nitrogen. Then, add 45 g (0.5 mol) of diethyl sulfide and 137 g (0.5 mol) of potassium hexafluoroantimonate.

[0076] 3.2) The mixture was stirred at 80°C for 6 h and then cooled to room temperature.

[0077] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent. The resulting solid was washed with deionized water and recrystallized to give 220.45 g of intermediate 2-2 with a yield of 83%. The molecular weight determined by MS was 529.98.

[0078] 4) Preparation of cationic photoinitiator intermediate 2-3

[0079] 4.1) In a dry three-necked flask, weigh 132.5 g of intermediate 2-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Slowly add 62.5 g of boron tribromide (0.25 mol) dropwise at 0°C. After the addition is complete, continue stirring and react for 3 h.

[0080] 4.2) After the reaction, the mixture was poured into ice water and subjected to liquid-liquid extraction. The separated organic phase was dried and the solvent was removed by rotary evaporation to obtain a crude product. The crude product was recrystallized from ethanol to obtain 104.55 g of cationic photoinitiator intermediate 2-3 with a yield of 81% and a molecular weight of 515.96 as determined by MS.

[0081] Example 4

[0082] The synthetic route of this embodiment is shown in the figure below:

[0083]

[0084] 3) Preparation of intermediate 3-2

[0085] 3.1) In a dry three-necked flask, weigh 142 g (0.5 mol) of Intermediate B-4 prepared in Example 1, add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Add 59 g (0.5 mol) of dipropyl sulfide and 137 g (0.5 mol) of potassium hexafluoroantimonate.

[0086] 3.2) The mixture was stirred at 80°C for 6 h and then cooled to room temperature.

[0087] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent. The resulting solid was washed with deionized water and recrystallized to give 246.24 g of intermediate 3-2 with a yield of 88%. The molecular weight determined by MS was 559.01.

[0088] 4) Preparation of cationic photoinitiator intermediate 3-3

[0089] 4.1) In a dry three-necked flask, weigh 139.5 g of intermediate 3-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Slowly add 62.5 g of boron tribromide (0.25 mol) dropwise at 0°C. After the addition is complete, continue stirring and react for 3 h.

[0090] 4.2) After the reaction, the mixture was poured into ice water and subjected to liquid-liquid extraction. The separated organic phase was dried and the solvent was removed by rotary evaporation to obtain a crude product. Recrystallization from ethanol gave 115.9 g of cationic photoinitiator intermediate 3-3 with a yield of 85% and a molecular weight of 543.99 as determined by MS.

[0091] Example 5

[0092] The synthetic route of this embodiment is shown in the figure below:

[0093]

[0094] 3) Preparation of intermediate 4-2

[0095] 3.1) In a dry three-necked flask, weigh 142 g of intermediate B-4 (0.5 mol), add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Then, add 59 g of diisopropyl sulfide (4-1, 0.5 mol) and 137 g of potassium hexafluoroantimonate (0.5 mol).

[0096] 3.2) The mixture was stirred at 80°C for 6 h and then cooled to room temperature.

[0097] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent. The resulting solid was washed with deionized water and recrystallized to afford 232.14 g of intermediate 4-2 with a yield of 83%. The molecular weight determined by MS was 558.01.

[0098] 4) Preparation of cationic photoinitiator intermediate 4-3

[0099] 4.1) In a dry three-necked flask, weigh 139.5 g of intermediate 4-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Slowly add 62.5 g of boron tribromide (0.25 mol) dropwise at 0°C. After the addition is complete, continue stirring and react for 3 h.

[0100] 4.2) After the reaction, the mixture was poured into ice water for liquid-liquid extraction. The separated organic phase was dried and the solvent removed by rotary evaporation to obtain a crude product. Recrystallization from ethanol yielded 118.3 g of cationic photoinitiator intermediate 4-3, with a yield of 87% and a molecular weight of 543.99 as determined by MS.

[0101] Example 6

[0102] The synthetic route of this embodiment is shown in the figure below:

[0103]

[0104] 3) Preparation of intermediate 5-2

[0105] 3.1) In a dry three-necked flask, weigh 142 g of intermediate B-4 (0.5 mol), add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Then, add 38 g of ethyl methyl sulfide (5-1, 0.5 mol) and 137 g of potassium hexafluoroantimonate (0.5 mol).

[0106] 3.2) The mixture was stirred at 80°C for 6 h and then cooled to room temperature.

[0107] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent. The resulting solid was washed with deionized water and recrystallized to give 209.1 g of intermediate 5-2 with a yield of 81%. The molecular weight determined by MS was 515.96.

[0108] 4) Preparation of cationic photoinitiator intermediate 5-3

[0109] 4.1) In a dry three-necked flask, weigh 129 g of intermediate 5-2 (0.25 mol), add an appropriate amount of anhydrous dichloromethane as the solvent, and slowly add 62.5 g of boron tribromide (0.25 mol) dropwise at 0°C. After the addition is complete, continue stirring and react for 3 h.

[0110] 4.2) After the reaction, the mixture was poured into ice water and subjected to liquid-liquid extraction. The separated organic phase was dried and the solvent was removed by rotary evaporation to obtain a crude product. Recrystallization from ethanol yielded 104.2 g of cationic photoinitiator intermediate 5-3, with a yield of 83%. The molecular weight determined by MS was 501.95.

[0111] Example 7

[0112] The synthetic route of this embodiment is shown in the figure below:

[0113]

[0114] 3) Preparation of intermediate 6-2

[0115] 3.1) In a dry three-necked flask, weigh 142 g of Intermediate B-4 (0.5 mol), add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Add 45 g of methyl propyl sulfide (6-1, 0.5 mol) and 137 g of potassium hexafluoroantimonate (0.5 mol).

[0116] 3.2) The mixture was stirred at 80°C for 6 h and then cooled to room temperature.

[0117] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent. The resulting solid was washed with deionized water and recrystallized to yield 241.2 g of intermediate 6-2, a 91% yield. The molecular weight was determined by MS to be 529.98.

[0118] 4) Preparation of cationic photoinitiator intermediate 6-3

[0119] 4.1) In a dry three-necked flask, weigh 129 g of intermediate 6-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Slowly add 62.5 g of boron tribromide (0.25 mol) dropwise at 0°C. After the addition is complete, continue stirring and react for 3 h.

[0120] 4.2) After the reaction, the mixture was poured into ice water for liquid-liquid extraction. The separated organic phase was dried and the solvent removed by rotary evaporation to obtain a crude product. Recrystallization from ethanol yielded 110.7 g of cationic photoinitiator intermediate 6-3, with a yield of 86%. The molecular weight determined by MS was 515.96.

[0121] Example 8

[0122] The synthetic route of this embodiment is shown in the figure below:

[0123]

[0124] 3) Preparation of intermediate 7-2

[0125] 3.1) In a dry three-necked flask, weigh 142 g of intermediate B-4 (0.5 mol), add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Add 101 g of dihexyl sulfide (7-1, 0.5 mol) and then 137 g of potassium hexafluoroantimonate (0.5 mol).

[0126] 3.2) The mixture was stirred at 85°C for 6 h and then cooled to room temperature.

[0127] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent, and the resulting solid was washed with deionized water and recrystallized to obtain 285.7 g of intermediate 7-2 with a yield of 89%. The molecular weight determined by MS was 642.10.

[0128] 4) Preparation of cationic photoinitiator intermediate 7-3

[0129] 4.1) In a dry three-necked flask, weigh 157 g of intermediate 7-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Cool the reaction system to 0°C and slowly add 62.5 g of boron tribromide (0.25 mol) dropwise. After the addition is complete, continue stirring the reaction for 4 h.

[0130] 4.2) After completion of the reaction, the reaction mixture was poured into ice water for neutralization, and liquid-liquid extraction was performed. The organic phase was collected, dried, and the solvent was removed by rotary evaporation. Finally, it was recrystallized from ethanol to obtain 136.9 g of cationic photoinitiator intermediate 7-3 with a yield of 87% and a molecular weight of 628.09 as determined by MS.

[0131] Example 9

[0132] The synthetic route of this embodiment is shown in the figure below:

[0133]

[0134] 3) Preparation of intermediate 8-2

[0135] 3.1) In a dry three-necked flask, weigh 142 g of intermediate B-4 (0.5 mol), add an appropriate amount of anhydrous butanone as solvent, and stir under nitrogen. Add 129 g of dioctyl sulfide (8-1, 0.5 mol) and then add 137 g of potassium hexafluoroantimonate (0.5 mol).

[0136] 3.2) The mixture was stirred at 85°C for 6 h and then cooled to room temperature.

[0137] 3.3) The reaction mixture was subjected to rotary evaporation to remove the solvent, and the resulting solid was washed with deionized water and recrystallized to obtain 293.2 g of intermediate 8-2 with a yield of 84%. The molecular weight determined by MS was 698.16.

[0138] 4) Preparation of cationic photoinitiator intermediate 8-3

[0139] 4.1) In a dry three-necked flask, weigh 174 g of intermediate 8-2 (0.25 mol) and add an appropriate amount of anhydrous dichloromethane as the solvent. Cool the reaction system to 0°C and slowly add 62.5 g of boron tribromide (0.25 mol) dropwise. After the addition is complete, continue stirring the reaction for 4 h.

[0140] 4.1) After completion of the reaction, the reaction mixture was poured into ice water for neutralization, and liquid-liquid extraction was performed. The organic phase was collected, dried, and the solvent was removed by rotary evaporation. Finally, it was recrystallized from ethanol to obtain 138.8 g of cationic photoinitiator intermediate 8-3 with a yield of 81% and a molecular weight of 684.15 as determined by MS.

[0141] Example 10

[0142] The synthetic route of this embodiment is shown in the figure below:

[0143]

[0144] 5) Preparation of water-soluble cationic photoinitiator

[0145] 5.1) In a dry three-necked flask, weigh 48.7 g of intermediate 1-3 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Stir under nitrogen. Then add 38.1 g of compound 1-4 (0.1 mol). Continue stirring at room temperature for 8 h to ensure sufficient reaction.

[0146] 5.2) After the reaction was complete, the solvent was removed by rotary evaporation, and the residue was dissolved in an appropriate amount of deionized water. The aqueous solution was decolorized with activated carbon and filtered to obtain a clear solution. The solution was then concentrated and freeze-dried to obtain cationic photoinitiator Y-1. The final yield was 67.81 g, with a yield of 81%. The H NMR spectrum data was:

[0147] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),8.34–8.12(m,2H),8.03(d,J=2.9Hz,1H),7.11(dd,J=1 5.0,3.1Hz,1H),6.07(ddt,J=33.3,20.0,12.3Hz,1H),5.45(ddt,J=33.5,4.0,1.9Hz,1H),5.23 (ddt,J=20.0,4.2,2.0Hz,1H),5.10(dt,J=12.5,1.9Hz,2H),4.51(d,J=7.5Hz,1H),4.42–4.21( m, 4H), 4.02 (td, J = 14.3, 1.0Hz, 2H), 3.77 (t, J = 7.0Hz, 2H), 3.64 (d, J = 7.5Hz, 1H), 3.52 (s, 4H).

[0148] Example 11

[0149] The synthetic route of this embodiment is shown in the figure below:

[0150]

[0151] 5) Preparation of water-soluble cationic photoinitiator

[0152] 5.1) In a dry three-necked flask, weigh 51.6 g of intermediate 2-3 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Under nitrogen, stir. Then, add 38.1 g of compound 2-4 (0.1 mol). The mixture is stirred at room temperature for 8 h to ensure complete reaction.

[0153] 5.2) After the reaction, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-2. The final yield was 76.5 g, with a yield of 85%. The H NMR spectrum data was:

[0154] 1 H NMR(500MHz,Chloroform)δ8.91(s,1H),8.35–8.12(m,2H),8.02(d,J=2.9Hz,1H),7.10(d d,J=14.9,3.0Hz,1H),6.07(ddt,J=33.3,19.8,12.3Hz,1H),5.44(ddt,J=33.5,4.0,1.9Hz ,1H),5.23(ddt,J=20.0,4.1,2.0Hz,1H),5.10(dt,J=12.5,1.9Hz,2H),4.92–4.71(m,2H), 4.33(dt,J=29.3,11.1Hz,4H), 4.01(t,J=8.0Hz,2H), 3.77(t,J=14.6Hz,2H), 3.52(s,4H).

[0155] Example 12

[0156] The synthetic route of this embodiment is shown in the figure below:

[0157]

[0158] 5) Preparation of water-soluble cationic photoinitiator

[0159] 5.1) In a dry three-necked flask, weigh 54.3 g of intermediate 3-3 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Under nitrogen, stir. Then, add 38.1 g of compound 3-4 (0.1 mol). The mixture is stirred at room temperature for 8 h to ensure complete reaction.

[0160] 5.2) After the reaction, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-3. The final yield was 80.3 g, with a yield of 87%. The H NMR spectrum data was:

[0161] 1H NMR(500MHz,Chloroform)δ8.91(s,1H),8.31–8.10(m,2H),8.02(d,J=3.1Hz,1H),7.1 0(dd,J=15.0,3.1Hz,1H),6.07(ddt,J=33.6,20.0,12.4Hz,1H),5.33(dddt,J=102.6, 20.0,4.2,2.0Hz,2H),5.10(dt,J=12.4,1.8Hz,2H),4.85(dd,J=7.5,0.6Hz,1H),4.51 –4.23(m,5H),4.02(t,J=8.4Hz,2H),3.77(t,J=6.6Hz,2H),3.52(s,4H),0.94(s,6H).

[0162] Example 13

[0163] The synthetic route of this embodiment is shown in the figure below:

[0164]

[0165] 5) Preparation of water-soluble cationic photoinitiator

[0166] 5.1) In a dry three-necked flask, weigh 54.3 g of intermediate 4-3 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Under nitrogen, stir. Then, add 38.1 g of compound 4-4 (0.1 mol). The mixture is stirred at room temperature for 8 h to ensure complete reaction.

[0167] 5.2) After the reaction, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-4. The final yield was 69.0 g, with a yield of 81%. The H NMR spectrum data was:

[0168] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),8.36–8.09(m,2H),8.03(d,J=2.9Hz,1H),7.11(dd,J =15.0,3.1Hz,1H),6.07(ddt,J=33.3,19.8,12.3Hz,1H),5.45(ddt,J=33.5,4.0,1.9Hz,1H), 5.23(ddt,J=20.0,4.2,2.0Hz,1H),5.10(ddt,J=12.4,2.0Hz,2H),4.74(dd,J=45.2,7.5Hz,2H ), 4.34(dt,J=29.3,11.2Hz,4H), 4.02(t,J=8.0Hz,2H), 3.77(t,J=14.6Hz,2H), 3.52(s,4H).

[0169] Example 14

[0170] The synthetic route of this embodiment is shown in the figure below:

[0171]

[0172] 5) Preparation of water-soluble cationic photoinitiator

[0173] 5.1) In a dry three-necked flask, weigh 50.2 g of intermediate 5-3 (0.1 mol), add an appropriate amount of anhydrous ethanol as solvent, and stir under nitrogen. Add 38.1 g of compound 5-4 (0.1 mol), and stir the mixture at room temperature for 8 h to ensure complete reaction.

[0174] 5.2) After the reaction, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-5. The final yield was 75.6 g, with a yield of 86%. The H NMR spectrum data was:

[0175] 1 H NMR (500MHz, Chloroform) δ8.86 (s, 1H), 8.31–7.78 (m, 3H), 7.06 (dd, J = 14.8, 2.9 Hz, 1H), 6.03 (ddt, J = 33.4, 19.8, 12. 3Hz, 1H), 5.50–4.49 (m, 6H), 4.31 (dt, J = 29.0, 11.1Hz, 4H), 3.99 (t, J = 8.0Hz, 2H), 3.74 (t, J = 14.4Hz, 2H), 3.50 (s, 4H).

[0176] Example 15

[0177] The synthetic route of this embodiment is shown in the figure below:

[0178]

[0179] 5) Preparation of water-soluble cationic photoinitiator

[0180] 5.1) In a dry three-necked flask, weigh 51.6 g of intermediate 6-3 (0.1 mol), add an appropriate amount of anhydrous ethanol as solvent, and stir under nitrogen. Add 38.1 g of compound 6-4 (0.1 mol), and stir the mixture at room temperature for 8 h to ensure complete reaction.

[0181] 5.2) After the reaction, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-6. The final yield was 77.1 g, with a yield of 88%. The H NMR spectrum data was:

[0182] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),8.37–8.09(m,2H),8.03(d,J=2.9Hz,1H),7.11(dd,J=15.0,2.9Hz,1H),6.23– 5.81(m,1H),5.60–4.76(m,6H),4.34(dt,J=20.8,9.1Hz,4H),3.85(dt,J=20.7,9.1Hz,4H),3.52(s,4H),0.94(s,3H).

[0183] Example 16

[0184] The synthetic route of this embodiment is shown in the figure below:

[0185]

[0186] 5) Preparation of water-soluble cationic photoinitiator

[0187] 5.1) In a dry three-necked flask, weigh 62.8 g of intermediate 7-3 (0.1 mol), add an appropriate amount of anhydrous ethanol as solvent, and stir under nitrogen. Add 38.1 g of compound 7-4 (0.1 mol), and stir the mixture at room temperature for 10 h to ensure complete reaction.

[0188] 5.2) After the reaction was completed, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-7. The final yield was 85.3 g, with a yield of 85%. The H NMR spectrum data was:

[0189] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),8.39–7.85(m,3H),7.11(dd,J=15.0,2.9Hz,1H),6.07(ddt,J=33.3,19.8,12.4Hz,1H),5.67–4.5 7(m,6H),4.33(dt,J=13.4,7.4Hz,4H),4.03(t,J=8.2Hz,2H),3.77(t,J=6.6Hz,2H),3.52(s,4H),1.49–1.03(m,12H),1.04–0.64(m,6H).

[0190] Example 17

[0191] The synthetic route of this embodiment is shown in the figure below:

[0192]

[0193] 5) Preparation of water-soluble cationic photoinitiator

[0194] 5.1) In a dry three-necked flask, weigh 68.4 g of intermediate 8-3 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Under nitrogen, stir. Then, add 38.1 g of compound 8-4 (0.1 mol). The mixture is stirred at room temperature for 10 h to ensure complete reaction.

[0195] 5.2) After the reaction was completed, the solvent was removed by rotary evaporation, and the residue was dissolved in deionized water and freeze-dried to obtain cationic photoinitiator Y-8. The final yield was 87.2 g, with a yield of 82%. The H NMR spectrum data was:

[0196] 1 H NMR(500MHz,Chloroform)δ8.91(s,1H),8.32–8.11(m,2H),8.02(d,J=2.9Hz,1H ),7.10(dd,J=15.0,2.9Hz,1H),6.07(ddt,J=33.3,19.8,12.4Hz,1H),5.55–4.94 (m,4H),4.73(ddd,J=44.1,7.5,0.6Hz,2H),4.47–4.16(m,4H),4.01(t,J=8.0Hz, 2H), 3.77 (t, J = 14.6Hz, 2H), 3.52 (s, 4H), 1.50–0.99 (m, 20H), 0.99–0.66 (m, 6H).

[0197] Example 18

[0198] The synthetic route of this embodiment is shown in the figure below:

[0199]

[0200] 5) Preparation of water-soluble cationic photoinitiator

[0201] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 9-1 (0.1 mol) and dissolve it in an appropriate amount of anhydrous ethanol as solvent. Slowly add 48.7 g of intermediate 1-3 (0.1 mol) and stir at room temperature. Heat the reaction system to reflux under nitrogen for 6 hours to ensure complete reaction.

[0202] 5.2) After the reaction was completed, the mixture was cooled to room temperature and poured into ice water with stirring to precipitate a solid. The solid was collected by filtration and repeatedly washed with deionized water until the filtrate was neutral. The resulting crude product was recrystallized from anhydrous ethanol to obtain 75.06 g of cationic photoinitiator Y-9 with a yield of 85%. The H NMR spectrum data were as follows:

[0203] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),8.36–7.88(m,3H),7.11(dd,J=15.0,2.9Hz,1H),5.80(ddt,J=33.5,20.0,12.4Hz,1H),5.1 9–4.65(m,4H),4.50–4.19(m,4H),4.02(t,J=8.0Hz,2H),3.87–3.66(m,3H),3.58–3.39(m,5H),2.24(dtt,J=12.3,10.3,2.0Hz,2H).

[0204] Example 19

[0205] The synthetic route of this embodiment is shown in the figure below:

[0206]

[0207] 5) Preparation of water-soluble cationic photoinitiator

[0208] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 10-1 (0.1 mol) and dissolve it in an appropriate amount of anhydrous ethanol as the solvent. Slowly add 51.6 g of intermediate 2-3 (0.1 mol) with stirring. The reaction system is heated to reflux under nitrogen and maintained for 6 h to ensure complete reaction.

[0209] 5.2) After the reaction, the reaction system was cooled to room temperature, and the mixture was poured into ice water with stirring to precipitate solids. The product was collected by suction filtration and repeatedly washed with deionized water until the filtrate was neutral. The crude product was recrystallized from anhydrous ethanol to obtain 73.51 g of cationic photoinitiator Y-10, with a yield of 81%. The H NMR spectrum data were as follows:

[0210] 1 H NMR (500MHz, Chloroform) δ8.92 (s, 1H), 8.37–7.90 (m, 3H), 7.11 (dd, J = 15.0, 2. 9Hz, 1H), 5.80 (ddt, J=33.6, 20.0, 12.5Hz, 1H), 4.96 (dddt, J=20.1, 18.2, 4.1, 2. 0Hz,2H),4.77(q,J=7.5Hz,2H),4.34(dt,J=29.3,11.2Hz,4H),4.01(t,J=8.1Hz ,2H),3.85–3.70(m,3H),3.62–3.40(m,5H),2.24(dtt,J=12.4,10.5,2.0Hz,2H).

[0211] Example 20

[0212] The synthetic route of this embodiment is shown in the figure below:

[0213]

[0214] 5) Preparation of water-soluble cationic photoinitiator

[0215] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 11-1 (0.1 mol) and add an appropriate amount of anhydrous acetone as solvent. Under nitrogen, stir slowly and slowly add 54.3 g of intermediate 3-3 (0.1 mol). The reaction system is heated to reflux and maintained for 5 h to ensure complete reaction.

[0216] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to precipitate solids. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 71.06 g of cationic photoinitiator Y-11 with a yield of 76%. The H NMR spectrum data are as follows:

[0217] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),8.42–7.91(m,3H),7.11(dd,J=15.0,2.9Hz,1H),5.80(ddt,J=33.3,20.0, 12.3Hz,1H),5.15–4.61(m,4H),4.34(dt,J=25.2,7.6Hz,4H),4.09–3.42(m,10H),2.52–2.24(m,2H),0.94(s,6H).

[0218] Example 21

[0219] The synthetic route of this embodiment is shown in the figure below:

[0220]

[0221] 5) Preparation of water-soluble cationic photoinitiator

[0222] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 12-1 (0.1 mol) and add an appropriate amount of anhydrous acetone as solvent. Slowly add 54.3 g of intermediate 4-3 (0.1 mol) while stirring under nitrogen. Heat the reaction system to reflux for 5 h to ensure complete reaction.

[0223] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to precipitate solids. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 75.43 g of cationic photoinitiator Y-12 with a yield of 81%. The H NMR spectrum data are as follows:

[0224] 1 H NMR(500MHz,Chloroform)δ8.90(s,1H),8.33–8.10(m,2H),8.01(d,J=3.1Hz,1H),7.09(dd,J=15.0, 3.1Hz,1H),5.79(ddt,J=33.3,20.0,12.4Hz,1H),4.94(dddt,J=19.9,18.2,4.1,2.0Hz,2H),4.58(d dd,J=17.2,7.5,0.6Hz,2H),4.33(dt,J=24.8,8.0Hz,4H),4.00(t,J=8.1Hz,2H),3.76(t,J=7.9Hz,2 H), 3.61 (t, J = 10.0Hz, 1H), 3.51 (s, 4H), 3.20 (t, J = 10.0Hz, 1H), 2.04 (dtt, J = 12.0, 10.0, 2.0Hz, 2H).

[0225] Example 22

[0226] The synthetic route of this embodiment is shown in the figure below:

[0227]

[0228] 5) Preparation of water-soluble cationic photoinitiator

[0229] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 13-1 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Slowly add 50.2 g of intermediate 5-3 (0.1 mol) while stirring under nitrogen. Heat the reaction system to reflux and maintain stirring for 6 h to ensure complete reaction.

[0230] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to precipitate solids. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 77.09 g of cationic photoinitiator Y-13 with a yield of 87%. The H NMR spectrum data are as follows:

[0231] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),8.43–7.81(m,3H),7.11(dd,J=15.0,2.9H z,1H),5.80(ddt,J=33.3,20.0,12.3Hz,1H),5.11–4.74(m,2H),4.65(ddd,J=37.7 ,7.5,0.6Hz,2H),4.34(dt,J=28.2,11.0Hz,4H),4.02(t,J=7.9Hz,2H),3.84–3.66 (m,3H),3.52(s,4H),3.44(t,J=10.2Hz,1H),2.19(dtt,J=12.1,10.2,1.8Hz,2H).

[0232] Example 23

[0233] The synthetic route of this embodiment is shown in the figure below:

[0234]

[0235] 5) Preparation of water-soluble cationic photoinitiator

[0236] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 14-1 (0.1 mol) and add an appropriate amount of anhydrous acetone as solvent. Under nitrogen, slowly add 51.6 g of intermediate 6-3 (0.1 mol) while stirring. Heat the reaction system to reflux and maintain the reaction for 8 hours to ensure complete reaction.

[0237] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to form a solid. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 76.69 g of cationic photoinitiator Y-14 with a yield of 84%. The H NMR spectrum data are as follows:

[0238] 1 H NMR(500MHz,Chloroform)δ8.90(s,1H),8.38–7.83(m,3H),7.09(dd,J=14.9,3.0Hz, 1H),5.79(ddt,J=33.6,20.0,12.4Hz,1H),4.95(dddt,J=19.9,18.0,4.1,2.0Hz,2H), 4.68(dd,J=25.3,7.5Hz,2H),4.33(dt,J=29.7,11.4Hz,4H),4.05(t,J=8.4Hz,2H),3. 88–3.64(m,3H),3.62–3.24(m,5H),2.24(dtt,J=12.1,10.2,1.9Hz,2H),0.94(s,3H).

[0239] Example 24

[0240] The synthetic route of this embodiment is shown in the figure below:

[0241]

[0242] 5) Preparation of water-soluble cationic photoinitiator

[0243] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 15-1 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Slowly add 62.8 g of intermediate 7-3 (0.1 mol) while stirring under nitrogen. Heat the reaction system to reflux and maintain the reaction for 10 hours to ensure complete reaction.

[0244] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to form a solid. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 88.22 g of cationic photoinitiator Y-15 with a yield of 87%. The H NMR spectrum data are as follows:

[0245] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),8.38–7.94(m,3H),7.11(dd,J=15.0,2.9Hz,1H),5.99–5.62(m,1H),5.13–4.61(m,4H),4.48 –4.23(m,4H),4.02(t,J=8.2Hz,2H),3.86–3.64(m,3H),3.58–3.31(m,5H),2.41–2.06(m,2H),1.42–1.07(m,12H),1.01–0.68(m,6H).

[0246] Example 25

[0247] The synthetic route of this embodiment is shown in the figure below:

[0248]

[0249] 5) Preparation of water-soluble cationic photoinitiator

[0250] 5.1) In a dry three-necked flask, weigh 39.6 g of compound 16-1 (0.1 mol) and add an appropriate amount of anhydrous ethanol as solvent. Slowly add 68.4 g of intermediate 8-3 (0.1 mol) while stirring under nitrogen. Heat the reaction system to reflux and maintain the reaction for 10 hours to ensure complete reaction.

[0251] 5.2) After the reaction is completed, the reaction mixture is cooled to room temperature and poured into ice water with stirring to form a solid. The product is collected by filtration and repeatedly washed with deionized water until the filtrate is neutral. The crude product is recrystallized from anhydrous ethanol to obtain 91.8 g of cationic photoinitiator Y-16 with a yield of 85%. The H NMR spectrum data are as follows:

[0252] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),8.40–7.88(m,3H),7.11(dd,J=15.0,3.1Hz,1H),5.80(ddt,J=33.3,19.8,12.3Hz,1 H),4.96(dddt,J=20.1,18.2,4.1,1.9Hz,2H),4.67–3.29(m,16H),2.46–1.97(m,2H),1.49–1.05(m,19H),1.00–0.61(m,6H).

[0253] Performance testing

[0254] (1) Solubility and dispersibility test: Evaluate the solubility or dispersibility of Y1-Y16 in water.

[0255] Experimental steps:

[0256] 1. Sample preparation: Weigh Y1 to Y16 and prepare solutions with concentrations of 1 mg / mL, 5 mg / mL, and 10 mg / mL, respectively.

[0257] 2. Stirring and dissolving: Add samples Y1 to Y16 into water and stir using a magnetic stirrer for 30 minutes to ensure complete dissolution.

[0258] 3. Solubility evaluation: Visually observe the state of each solution and record the solubility of Y1 to Y16 in water.

[0259] (2) Photoinitiation efficiency experiment: Determine the initiation efficiency of Y1-Y16 under UV light and evaluate their performance under different illumination times and concentrations.

[0260] Experimental steps:

[0261] 1. Sample preparation: Prepare a solution containing acrylate monomer (PEGDA) and add Y1 to Y16 respectively to prepare a mixed solution with a concentration of 1 wt%.

[0262] 2. UV curing: Place the above samples in a quartz vial and use a UV curing system (wavelength 365nm, light intensity 500mW / cm 2 ) Irradiate the sample with ultraviolet light and record the light response after 5 minutes.

[0263] 3. FT-IR monitoring: Use Fourier transform infrared spectrometer to monitor the polymerization reaction in real time, detect the intensity change of the characteristic peak of acrylate C=C double bond (about 1630 cm-1), and calculate the initiation efficiency.

[0264] (III) Initiator migration experiment: Based on the material synthesis, evaluate whether T1 to T16 migrate after the polymer is cured, verify its initiation efficiency and judge its stability.

[0265] Experimental steps:

[0266] 1. Film preparation: A mixture of Y1 to Y16 and vinyl ether monomers is cured by a UV curing system to prepare a polymer film.

[0267] 2. Immersion experiment: The prepared polymer films were immersed in water for 24 h, 48 h and 72 h respectively.

[0268] 3. Absorption peak detection: Take out the solution sample every 24 hours and use UV-visible spectrometer to detect whether there is photoinitiator in the immersion solution. Evaluate the migration situation by detecting the changes in the characteristic absorption peak.

[0269] The experimental results are shown in the following table.

[0270]

[0271]

[0272] The experimental results above indicate that Y-1 to Y-16 exhibit excellent solubility and dispersibility in water, ensuring uniformity during the photocuring process. Furthermore, with an initiation efficiency of ≥84%, Y-1 to Y-16 possess excellent photoinitiation capabilities, making them suitable for photocuring applications in epoxy resins, vinyl ether systems, and other applications. Finally, Y1 to Y-16 exhibit virtually no migration after curing the polymer film, making them suitable for applications with strict mobility requirements, such as food packaging and medical coatings.

[0273] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A cationic photoinitiator intermediate, characterized in that: Its molecular structure is one of the following formulas 1-3 to 8-3: 。 2. The method for preparing the cationic photoinitiator intermediate according to claim 1, characterized in that: At least the following steps are included: 1) Compound B-1 is dissolved in an organic solvent and cooled to 0-5°C. Phosgene and aluminum chloride as catalysts are slowly added, with a molar ratio of compound B-1 to phosgene B-2 of 1:1-1.

5. The mixture is stirred for 3-5 hours. The reaction mixture is then poured into ice water for neutralization, followed by liquid-liquid extraction, drying, and rotary evaporation to obtain intermediate B-3. 2) Dissolve the intermediate B-3 in an organic solvent, add N-bromosuccinimide and benzoyl peroxide in a molar ratio of 1:1 to 1.5, stir for 1 to 3 hours, then warm to room temperature and continue stirring for 3 to 5 hours. After the reaction, neutralize with sodium carbonate and perform liquid-liquid extraction to obtain the intermediate B-4, whose structure is shown in Formula B-4: ； 3) Intermediate B-4 is dissolved in an organic solvent, and dialkyl sulfide R1SR2 and potassium hexafluoroantimonate are added. The molar ratio of intermediate B-4, dialkyl sulfide R1SR2, and potassium hexafluoroantimonate is 1:1-1.5:1-1.

5. The reaction is stirred at room temperature for 7-9 hours, and then poured into ice water to precipitate a solid. The solid is filtered, washed, and dried to obtain intermediate 2, whose molecular structure is shown in Figure 2: ； 4) Dissolve the intermediate 2 in an organic solvent, cool to ≤0°C, slowly add boron tribromide dropwise, with the molar ratio of the intermediate 2 to boron tribromide being 1:1-1.5, stir for 0.5-1.5 hours, then warm to room temperature and continue stirring for 5-7 hours; after the reaction, pour the mixture into ice water for neutralization, perform liquid-liquid extraction, dry, and recrystallize to obtain the cationic photoinitiator intermediate as claimed in claim 1, 。 3. A water-soluble cationic photoinitiator, characterized in that Its molecular structure is one of the following formulas Y-1 to Y-16: 。 4. The method for preparing the water-soluble cationic photoinitiator according to claim 3, characterized in that: At least the following steps are included: 1) preparing the cationic photoinitiator intermediate according to claim 1; 2) dissolving the cationic photoinitiator intermediate in an organic solvent, and then adding an imidazole derivative, wherein the molar ratio of the cationic photoinitiator intermediate to the imidazole derivative is 1:1-1.5, heating the system temperature to 75-85°C, stirring and reacting for 11-13 hours, and then cooling and removing the organic solvent by rotary evaporation, washing and recrystallizing to obtain a water-soluble cationic photoinitiator as described in claim 3.

5. The method for preparing a water-soluble cationic photoinitiator according to claim 4, wherein: In step 2), the molecular structure of the imidazole derivative is shown in Formula 1 or Formula 4: 。

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