LED sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridinium salt

Abstract

The invention relates to the field of high-molecular compounds connected to polymers of styrene or alkyl-substituted styrene, in particular to an LED-sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridinium as well as a preparation method and application of the LED-sensitive ketoxime ester type water-soluble photoinitiator. An LED sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridinium is characterized in that a styrene group is connected with a pyridine ring to form a diarylethene structure, and ketoxime ester is connected to the para-position of a double bond on a benzene ring. The invention relates to a preparation method of an LED-sensitive styryl pyridinium-based ketoxime ester type water-soluble photoinitiator. The preparation method is characterized by being implemented in sequence according to reaction equations (a), (b), (c) and (d). The light absorption performance is good, and the matching performance with an LED light source is good.

Description

[0001] And its manufacturing method and application Technical Field The invention relates to the field of polymer compounds connected to polymers of styrene or alkyl-substituted styrene, in particular to an LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styryl pyridinium salt, and a preparation method and application thereof. Background Art

[0002] Photoinitiator compounds are an important class of fine organic chemical materials. In the field of radiation curing technology using ultraviolet light or visible (UV) light or LED (Light-Emitting Diode) as light source, photoinitiator compounds that can generate free radical active species under light irradiation conditions are key species that induce efficient photopolymerization reactions in olefin-containing unsaturated systems, and are therefore one of the important radiation curing formulation components. Photocuring has many advantages such as energy saving and environmental protection, high efficiency and rapidity, and time-space controllability. It has been widely used in traditional fields such as coatings, inks, adhesives, and high-tech products such as 3D printing. However, traditional photocuring still has some shortcomings, especially that active diluents and a small amount of volatile organic solvents are generally added to the system, which usually harms human health and pollutes the environment. Water-soluble photoinitiators can replace active diluents with water during use, which is safer and more environmentally friendly, especially with potential biological applications, such as hydrogels, drug carriers, etc.

[0003] The most commonly used water-soluble one on the market is I2959, and its structural formula is shown in structural formula (A): --(First) However, I2959 has poor water solubility and low absorption within the wavelength of LED light source. Compared with traditional UV curing, LED light curing using light emitting diodes as light sources has significant advantages such as high energy utilization, low thermal effect, and no ozone generation. Therefore, the development of a series of LED-initiated water-soluble photoinitiators through reasonable molecular design has great application prospects. Summary of the invention

[0004] In order to overcome the defects of the prior art and provide a polymer with good light absorption performance and good matching with LED light sources, the present invention discloses an LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styrylpyridinium salt, and a preparation method and application thereof.

[0005] The present invention achieves the purpose of the invention through the following technical solutions: An LED-sensitive ketoxime ester-type water-soluble photoinitiator based on styryl pyridinium salt, characterized in that: a styrene group is connected to a pyridine ring to form a diarylethene structure, and the ketoxime ester is connected to the para position of the double bond on the benzene ring, thereby forming an initiator structure with a diarylethene conjugated structure. The specific molecular structure is shown in general formula (i): —(i) In the general formula (I): a. R 1 , R 2 Select any one from a.1 to a.8 below: a.1 A straight or branched chain alkyl group containing 1 to 20 carbon atoms, a.2 C 3 ~C 12 Cycloalkyl, a.3 Cycloalkylalkyl, a.4 Cycloheteroalkylalkyl, a.5 C 6 ~C 12 Substituents, including aromatic groups, hydrogen, halogen atoms, R, OR, SR, SOR, SO 2 R, NRR', CH 2 OH, CH 2 OR, CH 2 OCOR, CH 2 SR, CH 2 SCOR and CH 2 NRR', a.6 Alkyl substituents; said substituents include aryl, hydrogen, halogen atoms, R, OR, SR, SOR, SO 2 R, NRR', CH 2 OH, CH 2 OR, CH 2 OCOR, CH 2 SR, CH 2 SCOR and CH 2 NRR', R and R' in a.5 and a.6 are selected from any of the following a.7 and a.8 respectively: a.7 C 1 ~C 24 A straight chain or branched alkyl group, a.8 C 6 ~C 24 Aryl; b. R 3 Choose any one from b.1 to b.5 below: b.1 A straight-chain or branched-chain alkyl group containing 1 to 10 carbon atoms, b.2 C 3 ~C 12 Cycloalkyl, b.3 Cycloalkylalkyl, b.4 C 6 ~C 12 Aryl, b.5 Alkylaryl; c.X - is the corresponding anion; The photoinitiator itself and the radiation curing system in which it participates have a certain inhibitory effect on certain types of bacteria.

[0006] The LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: X - For various water-soluble anions, X - Select any one from c.1 to c.9 below: c.1 I - , c.2 CF 3 SO 3 - , c.3 Br - , c.4 C 7 H 7 SO 3 - , c.5 CH 3 COO - , c.6 CF 3 COO - , c.7 , c.8 , c.9 ; R includes at least one of the following structures d.1 and d.2: d.1 Use fluorine atoms to replace hydrogen atoms to form a fluorocarbon chain structure, d.2 Contains 1 to 6 non-consecutive oxygen, nitrogen or sulfur elements.

[0007] The LED-sensitive ketoxime ester type water-soluble photoinitiator based on styryl pyridinium salt is characterized in that when R and R' exist at the same time, a 3-6-membered ring system structure is formed to replace various substituted aromatic groups.

[0008] The method for preparing the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: carrying out the following steps in sequence: I. + —(a) According to reaction formula (a), 4-vinylpyridine and 1 The substituted 4'-bromophenone is catalyzed by bis(triphenylphosphine)palladium dichloride and potassium carbonate to prepare an intermediate a. The solvent used in the reaction is DMF. The reaction temperature is 100°C to 110°C. The reaction time is 6 hours to 12 hours. The intermediate a is purified by column chromatography or recrystallization. The molecular structure of the intermediate a is shown in the general formula (ii): - (ii); II. —(b) According to reaction formula (b), the intermediate a generated in step I is reacted with isoamyl nitrite in the presence of concentrated hydrochloric acid to prepare an intermediate b having a ketoxime structure. The solvent used in the reaction is tetrahydrofuran, the reaction temperature is 0°C, and the reaction time is 12 hours to 36 hours. After extraction and reduced pressure distillation to remove the organic solvent, the intermediate b is obtained and can be directly used in the next reaction without further purification. The molecular structure of the intermediate b is shown in general formula (iii): - (iii); III. - (c) According to reaction formula (c), the intermediate b generated in step II is reacted with anhydride or the corresponding acid chloride in the presence of triethylamine to prepare an intermediate c having a ketoximate or oxime ester structure. The solvent used in the reaction is dichloromethane, the reaction temperature is 0°C, the reaction time is 12 hours to 36 hours, and the intermediate c is purified by column chromatography or recrystallization. The molecular structure of the intermediate c is shown in general formula (iv): - (iv); IV. —(d) According to reaction formula (d), the intermediate c generated in step III is reacted with R 3-X directly reacts to generate a salt solution, the solvent used in the reaction is DMF, the reaction temperature is 40°C to 90°C, the reaction time is 12 hours to 36 hours, the salt solution generated by the reaction is added to ether to obtain a precipitate, the precipitate is filtered and dried to obtain the final product, i.e., a water-soluble photoinitiator, and the molecular structure of the final product is shown in general formula (i).

[0009] The method for preparing the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: In step IV: X - Select any one from c.1 to c.9 below: c.1 I - , c.2 CF 3 SO 3 - , c.3 Br - , c.4 C 7 H 7 SO 3 - , c.5 CH 3 COO - , c.6 CF 3 COO - , c.7 , c.8 , c.9 , X - When structures c.5 to c.9 are selected, iodine pyridine salt is first prepared, dissolved in water, and then an equimolar amount of silver salt is added to the solution, stirred at room temperature for 1 h to 12 h, filtered, and the filtrate is collected, and the solvent is removed by vacuum distillation. The obtained solid is washed with ether, filtered, and dried to obtain the target structure; R 3 -X is selected from any one of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl trifluoromethanesulfonate, methyl iodide, ethyl iodide and propyl iodide; R 3 -X is selected from methyl p-toluenesulfonate, the solvent used is ethyl acetate; R 3 When -X is selected from methyl trifluoromethanesulfonate, methyl iodide, ethyl iodide and propyl iodide, the solvent used is ether.

[0010] The application of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: implementing the following steps in sequence: S1. Ingredients: The mass fractions of monomer, water-soluble photoinitiator and auxiliary agent are as follows: Monomer: 100, Water-soluble photoinitiator: 1~1.5, Additives: 0-4.5; S2. Stirring: The monomer, water-soluble photoinitiator and auxiliary agent are mixed and stirred to fully dissolve the three to form a polymer; S3. Irradiation: Irradiating the polymer with light sources of different wavelengths or different light intensities, wherein the light source is selected from any one of a mercury lamp, LEDs with an emission wavelength of 313 nm to 425 nm, and LDI with an emission wavelength of 313 nm to 425 nm; S4. The polymerization conversion rate was studied by analyzing the changes in the characteristic peaks of the polymer obtained in S3 using an online infrared method; The polymer may also contain inorganic or organic fillers and / or colorants (such as pigments or dyes, etc.) added according to actual needs, as well as other additives (such as ultraviolet absorbers, light stabilizers, flame retardants, leveling agents or defoamers, etc.) and solvents and other arbitrary components; The water-soluble monomer is an olefinic polymerizable monomer, including but not limited to: (meth)acrylamide monomer, (meth)acrylic acid, sodium (meth)acrylate, potassium (meth)acrylate, N-vinyl pyrrolidone, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, sodium 2-acrylamide-2-methylpropane sulfonate, etc.

[0011] The application of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: A water-soluble photoinitiator and a water-soluble monomer are dissolved in water to form a solution, and a light source such as a 365nm to 425nm LED is used to irradiate the solution, and the solution is stimulated to absorb single photons to achieve polymerization or cross-linking of the water-soluble monomers, thereby preparing an antibacterial hydrogel system or water-based coating.

[0012] The application of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: Used to prepare a mixture for curing by light (ultraviolet light or visible light or LED light or equivalent light source), the formula of the mixture is as follows: Component I: contains at least one water-soluble photoinitiator described by general formula (i), and Component II: contains at least one free radical polymerizable compound containing an olefinic bond (C=C); Taking the total mass of the mixture as 100 parts, the mass fraction of component I is 0.01 to 30; Compounds containing olefinic free radical polymerizable groups include, but are not limited to: (meth)acrylic acid copolymers with (meth)acryloyl functional groups, polyurethane formate (meth)acrylates, polyester (meth)acrylates, unsaturated polyesters, polyether (meth)acrylates, silicone (meth)acrylates, epoxy resin (meth)acrylates, polyethylene glycol diacrylates, and the like, as well as water-soluble or water-dispersible analogs of the above substances.

[0013] The application of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator is characterized by: The mass fraction of component I is 0.5 to 10; Component II is selected from compounds or mixtures that are crosslinked by olefin free radical polymerization; component II is selected from monomers, oligomers or prepolymers, or aqueous dispersions of the monomers, oligomers or prepolymers, or mixtures or copolymers of at least two of the monomers, oligomers and prepolymers.

[0014] Examples of compounds that conform to the structure of general formula (i) are as follows, which are respectively represented by general formula (i-1) to general formula (i-18): ——(i-1), ——(i-2), ——(i-3), ——(i-4), ——(i-5), ——(i-6), ——(i-7), ——(i-8), ——(i-9), ——(i-10), ——(i-11), ——(i-12), ——(i-13), ——(i-14), ——(i-15), ——(i-16), ——(i-17), ——(i-18).

[0015] Ketoximate esters with distyryl structures have good light absorption properties in both near-ultraviolet and visible light regions, and their thermal stability is also relatively excellent, making them a class of free radical photoinitiators with great potential application value. In addition, positively charged compounds such as compounds with quaternary ammonium salts, quaternary phosphonium salts, guanidine salts, and pyridinium salts have been shown to be able to electrostatically attract bacteria, thereby interfering with the normal physiological activities of bacteria and killing them, achieving an antibacterial effect.

[0016] In response to the above technical challenges, a class of ketoxime ester-type water-soluble photoinitiators derived from styrylpyridinium salts was invented. In the field of photopolymerization, water-soluble photoinitiators with high photosensitivity, high stability, and easy preparation, as well as antibacterial properties are very necessary. In addition, the synthesis steps of such initiators should be simple, low in cost, and environmentally friendly in the synthesis process, with less waste. With the continuous improvement of people's awareness of environmental protection, production safety, and various requirements for labor protection, as well as the continuous development of photopolymerization technology, low-energy, high-safety, and environmentally friendly exposure lamps such as LED and LDI have become a trend in the application and development of technology in this field.

[0017] The present invention relates to the technical field of new material organic chemicals, and in particular to a class of LED-sensitive ketoxime ester-type water-soluble photoinitiators based on styryl pyridinium salts, which are of the structure shown in general formula (I), wherein the styryl group and the pyridine ring form a diarylethene structure, and the oxime ester is connected to the para position of the double bond on the benzene ring, thereby forming an initiator structure with a certain conjugated structure, and the corresponding X- is p-toluenesulfonate, trifluoromethanesulfonate, iodide ion, etc. This series of photoinitiators has strong light absorption ability in the near-ultraviolet-visible light region and high photolysis efficiency. The pyridinium salts with different anions not only provide water solubility, but also can play a certain antibacterial role. Its chemical preparation process technology, its use as a radiation curing photoinitiator, and its application in radiation curing formula products, especially UV-Vis-LED-excitable light-cured water-based coatings or inks, 3D printing, antibacterial hydrogels and many other occasions are broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the 1H NMR spectrum of the molecule of the structural formula i-3 in the present invention in DMSO-d6, Figure 2is the 1H NMR spectrum of the molecule of the structural formula i-5 in the present invention in DMSO-d6, Figure 3 is the UV-visible absorption spectrum of the molecules of the structural formula i-3 and i-5 in the present invention in water, Figure 4 This is a kinetic curve of the free radical polymerization rate of thick films induced by molecules of the i-3 and i-5 structural formulas of the present invention under the excitation of a 365nm LED light source. Figure 5 This is a kinetic curve of the free radical polymerization rate of thick films induced by molecules of the i-3 and i-5 structural formulas of the present invention under the excitation of a 385nm LED light source. Figure 6 It is a kinetic curve diagram of the thick film free radical polymerization rate induced by the molecules of the structural formula i-3 and i-5 in the present invention under the excitation of a 405nm LED light source. DETAILED DESCRIPTION

[0019] The present invention is further described below by means of specific examples.

[0020] Example 1 Prepare a ketoxime ester type water-soluble photoinitiator as shown in general formula (i-3): ——(i-3).

[0021] I. + ——(i-3-i), According to reaction formula (i-3-i), 47.56 mmol of 4-vinylpyridine, 47.56 mmol of 4'-bromovalerophenone, 71.34 mmol of potassium carbonate and 60 mL of DMF were added in a dry three-necked flask in sequence. 2 Add 0.47 mmol of the catalyst bis(triphenylphosphine)palladium dichloride under the atmosphere, and heat the reaction in a 100°C oil bath. After 6 hours, the raw material disappears under TCL monitoring, and DMF is concentrated under reduced pressure. The reaction solution is poured into 100 ml of deionized water, and the precipitate is filtered and dried, and purified by column chromatography to obtain a light yellow solid styrylpyridine compound, namely intermediate i-3-a, with a yield of 90.31%. The molecular structure of intermediate i-3-a is shown in the general formula (i-3-aa): ——(i-3-aa).

[0022] II. ——(i-3-ii), According to reaction formula (i-3-ii), in a dry three-necked flask, add 40mmol of the intermediate i-3-a prepared in step I to 60ml of tetrahydrofuran solution, place in an ice bath at 0℃ and stir, add 200mmol of 38% concentrated hydrochloric acid and 60mmol of isoamyl nitrite dropwise in sequence, and place at room temperature to stir and react. After 12 hours, TCL monitoring shows that the raw material disappears, the reaction solution is poured into 50ml of water, the organic layer is extracted with dichloromethane, dried and distilled under reduced pressure to obtain a yellow solid oxime compound, namely the intermediate i-3-b, with a yield of 90.01%. The molecular structure of the intermediate i-3-b is shown in the general formula (i-3-ba): ——(i-3-ba).

[0023] III. ——(i-3-iii), According to reaction formula (i-3-iii), in a dry three-necked flask, add 35mmol of the intermediate i-3-b prepared in step II and 175mmol of anhydrous triethylamine in 60ml of anhydrous dichloromethane, place in an ice bath under nitrogen protection and cool to 0°C, add 87.5mmol of acetic anhydride dropwise, continue to react at 0°C for half an hour and place at room temperature to continue the reaction. After 12 hours, TCL monitoring shows that the raw material disappears, the reaction solution is poured into 50ml of water, the organic phase is extracted with dichloromethane, dried and distilled under reduced pressure, purified by column chromatography, and the product is a light yellow solid keto-oxime ester compound, namely intermediate i-3-c, with a yield of 85.10%. The molecular structure of intermediate i-3-c is shown in general formula (i-3-ca): ——(i-3-ca).

[0024] IV. ——(i-3-iv), According to reaction formula (i-3-iv), in a dry single-necked flask, add 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of methyl p-toluenesulfonate to 20 ml of DMF solution, and place in a 60°C oil bath under nitrogen protection to stir and react. After 12 hours, the raw material disappears as monitored by TCL. After cooling to room temperature, ethyl acetate is added to the reaction solution until a precipitate is precipitated. The precipitate is filtered out and dried. The product is a light yellow solid ketoximate ester type water-soluble photoinitiator, i.e., the target product shown in general formula (i-3), with a yield of 98.05%.

[0025] HR-MS (C 21 H 23 N 2 O 3+ ): Theoretical: m / z: 351.1704; Experimental: 351.1710.

[0026] NMR of the target product represented by general formula (i-3): 1H NMR (400 MHz, DMSO-d6) δ 8.92 (d, J = 6.5 Hz, 2H), 8.28 (d, J = 6.4 Hz, 2H), 8.14 – 8.04 (m, 3H), 7.92 (d, J =8.3 Hz, 2H), 7.72 (d, J = 16.4 Hz,1H), 7.48 (d, J = 7.8 Hz, 2H), 7.11 (d, J =7.8 Hz, 2H), 4.28 (s, 3H), 2.81 – 2.68 (m, 2H), 2.28 (s, 3H), 2.26 (s, 3H),1.57 (p, J = 7.4 Hz, 2H), 0.95 (t, J = 7.4 Hz, 3H).

[0027] For detailed NMR spectra, see Figure 1 .

[0028] Example 2 Prepare a ketoxime ester type water-soluble photoinitiator as shown in the general formula (i-5): ——(i-5).

[0029] Steps I to III are the same as in Example 1.

[0030] IV. ——(i-5-iv) According to reaction formula (i-5-iv), in a dry single-necked flask, add 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of methyl iodide to 20 ml of DMF solution, and place in a 60°C oil bath under nitrogen protection to stir and react. After 12 hours, the raw material disappears as monitored by TCL. After cooling to room temperature, ether is added to the reaction solution until a precipitate is precipitated. The precipitate is filtered out and dried. The product is a light yellow solid ketoxime ester type water-soluble photoinitiator, i.e., the target product shown in general formula (i-5).

[0031] HR-MS (C 21 H 23 IN 2 O 3 ): Theoretical: m / z: 351.1704; Experimental: 351.1714.

[0032] NMR of the target product represented by general formula (i-5): 1H NMR (400 MHz, DMSO-d6) δ 8.93 (d, J= 6.4 Hz, 2H), 8.29 (d, J = 6.7 Hz, 2H), 8.21 – 8.02 (m, 3H), 7.93 (d, J =8.2 Hz, 2H), 7.73 (d, J = 16.4 Hz, 1H), 4.29 (s, 3H), 2.80 – 2.68 (m, 2H),2.26 (s, 3H), 1.58 (h, J = 7.6 Hz, 2H), 0.94 (t, J = 7.4 Hz, 3H).

[0033] For detailed NMR spectra, see Figure 2 .

[0034] Example 3 Prepare a ketoxime ester type water-soluble photoinitiator as shown in the general formula (i-6): ——(i-6).

[0035] Step I and step II are the same as in Example 1.

[0036] III. ——(i-6-iii), According to reaction formula (i-6-iii), in a dry three-necked flask, add 35mmol of the intermediate i-3-b prepared in step II and 175mmol of anhydrous triethylamine in 60ml of anhydrous dichloromethane, place in an ice bath under nitrogen protection and cool to 0°C, add 87.5mmol of p-methylbenzoyl chloride dropwise, continue to react at 0°C for half an hour and place at room temperature to continue the reaction. After 12 hours, TCL monitoring shows that the raw material disappears, the reaction solution is poured into 50ml of water, the organic phase is extracted with dichloromethane, dried and distilled under reduced pressure, purified by column chromatography, and the product is a light yellow solid ketoxime ester compound, namely intermediate i-3-c, with a yield of 85.10%. The molecular structure of intermediate i-6-c is shown in the general formula (i-6-ca): ——(i-6-ca).

[0037] IV. ——(i-6-iv), According to reaction formula (i-6-iv), in a dry single-necked flask, add 10 mmol of the intermediate i-3-c obtained in step III and 40 mmol of methyl iodide to 20 ml of DMF solution, and place in a 60°C oil bath under nitrogen protection to stir and react. After 12 hours, the raw material disappears as monitored by TCL. After cooling to room temperature, ethyl acetate is added to the reaction solution until a precipitate is precipitated. The precipitate is filtered out and dried. The product is a light yellow solid ketoxime ester type water-soluble photoinitiator, i.e., the target product as shown in general formula (i-6).

[0038] HR-MS (C 27 H 27 IN 2 O 3 ): Theoretical: m / z: 427.2017; Experimental: 427.2021.

[0039] Example 4 The UV-visible absorption spectra and related photophysical parameters of the two target products represented by the general formula (i-3) prepared in Example 1 and the general formula (i-5) prepared in Example 2 were tested.

[0040] Accurately weigh a certain amount of the target product obtained in Example 1 and Example 2 and the sample in the comparative example, dissolve them in a volumetric flask with water as solvent, and then test the UV-visible absorption spectrum. The specific curve is as follows: Figure 3 The maximum absorption wavelength, the molar extinction coefficient at the maximum absorption wavelength and the molar extinction coefficient at 365nm, 385nm and 405nm are shown in Table 1: Table 1: Light absorption properties of two initiators in water in the examples It can be seen from Table 1 that the target products prepared in the two examples have good light absorption performance in the range from UVA to visible light, and are expected to be used in the field of photoinitiated polymerization in this wavelength range.

[0041] Example 5 The two target products represented by the general formula (i-3) obtained in Test Example 1 and the general formula (i-5) obtained in Test Example 2 were subjected to light curing experiments in a water-based formulation containing acrylamide monomer under the conditions of LED @ 365nm, 385nm and 405nm: Recipe 1: Monofunctional monomer aqueous solution: mass fraction 99, Photoinitiator: mass fraction 1; The monofunctional monomer aqueous solution is a solution of acrylamide (AM) and water mixed in a mass ratio of 1:1, and the photoinitiator is the target product represented by the general formula (i-3) obtained in Example 1.

[0042] Recipe 2: Monofunctional monomer aqueous solution: mass fraction 99, Photoinitiator: mass fraction 1; The monofunctional monomer aqueous solution is a solution of acrylamide (AM) and water mixed in a mass ratio of 1:1, and the photoinitiator is the target product represented by the general formula (i-5) obtained in Example 2.

[0043] The photopolymerization kinetic curves of the two formulation systems under the excitation of LED light sources at 365nm, 385nm and 405nm were tested by FT-IR. The conversion rate of acrylamide was calculated based on the change in the in-plane bending vibration peak area of ​​olefin CH at 1280cm-1. The specific curves are as follows: Figure 4 , Figure 5 and Figure 6 shown.

[0044] Example 6 The minimum inhibitory concentration (MIC) of the two target products represented by the general formula (i-3) prepared in Example 1 and the general formula (i-5) prepared in Example 2 was tested.

[0045] The microbroth dilution method was used for determination. First, appropriate LB broth (autoclaved) was added to a 96-well plate, and then the 2 mg / mL target product to be tested dissolved in water was added to the first well of each row of the 96-well plate, and diluted by two-fold dilution. Finally, an equal volume of bacterial solution was inoculated into each well plate, and the final drug concentrations of each test group were 500 μg / mL, 250 μg / mL, 125 μg / mL, 62.5 μg / mL, 31.25 μg / mL, 16 μg / mL, 8 μg / mL, 4 μg / mL, 2 μg / mL, and 1 μg / mL. Two parallel blank control groups (i.e., no sample was added) were set up for the test at the same time, and the culture was kept at 37°C for 8 hours. The growth of bacteria was tested by the change in the absorbance OD value of the test sample solution, and the MIC value of the sample was read. In this embodiment, the concentration corresponding to the OD value increment of half of the blank control group is used as the MIC value of the drug. The MIC values ​​of the two target products against Escherichia coli and Staphylococcus aureus are shown in Table 2: Table 2: MIC values ​​of the two target products against Escherichia coli and Staphylococcus aureus It can be seen from Table 2 that the target products prepared in the two examples have obvious antibacterial effects.

Claims

1. A LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator, characterized in that: The styrene group is connected to the pyridine ring to form a diarylethylene structure, and the ketoxime ester is connected to the para position of the double bond on the benzene ring. The specific molecular structure is shown in general formula (i): ——(i) In the general formula (i): a. R1 and R2 can each select one of the following: a.1 to a.6: a.1 A straight-chain or branched alkyl group containing 1 to 20 carbon atoms, a.2 C3~C 12 Cycloalkyl, a.3 Cycloalkylalkyl, a.4 Cycloheteroalkylalkyl, a.5 C6~C 12 Substituents, wherein the substituents include aromatic groups, hydrogen, halogen atoms, R, OR, SR, SOR, SO2R, NRR', CH2OH, CH2OR, CH2OCOR, CH2SR, CH2SCOR and CH2NRR', a.6 alkyl substituents; said substituents include aryl, hydrogen, halogen atoms, R, OR, SR, SOR, SO2R, NRR', CH2OH, CH2OR, CH2OCOR, CH2SR, CH2SCOR and CH2NRR', R and R' in a.5 and a.6 are selected from any of a.7 and a.8 below: a.7 C1~C 24 A straight chain or branched alkyl group, a.8 C6~C 24 Aryl; b. R3 selects one of the following b.1 to b.5: b.1 A straight-chain or branched-chain alkyl group containing 1 to 10 carbon atoms, b.2 C3~C 12 Cycloalkyl, b.3 Cycloalkylalkyl, b.4 C6~C 12 Aryl, b.5 Alkylaryl; c.X - is the corresponding anion.

2. The LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator according to claim 1, characterized in that: X - Select any one from c.1 to c.9 below: c.1 I - , c.2 CF3SO3 - , c.3 Br - , <h2 style=";text-align:left;direction:ltr">c.4 C7H7SO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , c.5 CH3COO - , c.6 CF3COO - , c.7 ， c.8 ， c.9 ； R includes at least one of the following structures d.1 and d.2: d.1 Use fluorine atoms to replace hydrogen atoms to form a fluorocarbon chain structure, d.2 Contains 1 to 6 non-consecutive oxygen, nitrogen or sulfur elements.

3. The LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator according to claim 2, characterized in that: When R and R' exist at the same time, a 3-6 membered ring structure is formed to substitute various substituted aromatic groups.

4. The method for preparing the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator according to any one of claims 1 to 3, characterized in that: Follow the steps below to implement: I. + ——(a), According to reaction formula (a), 4-vinylpyridine and 4'-bromophenone with different R1 substituents are prepared under the catalysis of bis(triphenylphosphine)palladium dichloride and the action of potassium carbonate to prepare intermediate a. The solvent used in the reaction is DMF. The reaction temperature is 100°C to 110°C. The reaction time is 6 hours to 12 hours. The intermediate a is purified by column chromatography or recrystallization. The molecular structure of the intermediate a is shown in general formula (ii): ——(ii); II. ——(b), According to reaction formula (b), the intermediate a generated in step I is reacted with isoamyl nitrite in the presence of concentrated hydrochloric acid to prepare an intermediate b having a ketoxime structure. The solvent used in the reaction is tetrahydrofuran, the reaction temperature is 0° C., the reaction time is 12 hours to 36 hours, and the intermediate b is obtained after extraction and reduced pressure distillation. The molecular structure of the intermediate b is shown in general formula (iii): ——(iii); III. ——(c), According to reaction formula (c), the intermediate b generated in step II is reacted with anhydride or the corresponding acid chloride in the presence of triethylamine to prepare an intermediate c having a ketoximate or oxime ester structure. The solvent used in the reaction is dichloromethane, the reaction temperature is 0°C, the reaction time is 12 hours to 36 hours, and the intermediate c is purified by column chromatography or recrystallization. The molecular structure of the intermediate c is shown in general formula (iv): ——(iv); IV. ——(d), According to reaction formula (d), the intermediate c generated in step III is directly reacted with R3-X to generate a salt solution. The solvent used in the reaction is DMF. The reaction temperature is 40°C to 90°C. The reaction time is 12 hours to 36 hours. The salt solution generated by the reaction is added to ether to obtain a precipitate. The precipitate is filtered and dried to obtain the final product, i.e., a water-soluble photoinitiator. In which, X - For I - Br - CF3SO3 - or C7H7SO3 - , the molecular structure of the final product is shown in general formula (i).

5. The method for preparing the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator according to claim 4, characterized in that: In step IV: X - Select any one from c.1 to c.9 below: c.1 I - , c.2 CF3SO3 - , c.3 Br - , <h2 style=";text-align:left;direction:ltr">c.4 C7H7SO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> , c.5 CH3COO - , c.6 CF3COO - , c.7 ， c.8 ， c.9 ， X - When structures c.5 to c.9 are selected, iodine pyridine salt is first prepared, dissolved in water, and then an equimolar amount of silver salt is added to the solution, stirred at room temperature for 1 h to 12 h, filtered, and the filtrate is collected, and the solvent is removed by vacuum distillation. The obtained solid is washed with ether, filtered, and dried to obtain the target structure; R3-X is selected from any one of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl trifluoromethanesulfonate, methyl iodide, ethyl iodide, propyl iodide, ethyl bromide, and propyl bromide; When R3-X is selected from methyl p-toluenesulfonate, the solvent used is ethyl acetate; when R3-X is selected from methyl trifluoromethanesulfonate, methyl iodide, ethyl iodide and propyl iodide, the solvent used is ether.

6. The use of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator as claimed in claim 4, characterized in that: Follow the steps below to implement: S1. Ingredients: The mass fractions of monomer, water-soluble photoinitiator and auxiliary agent are as follows: Monomer: 100, Water-soluble photoinitiator: 1~1.5, Additives: 0-4.5; S2. Stirring: The monomer, water-soluble photoinitiator and auxiliary agent are mixed and stirred to fully dissolve the three to form a polymer; S3. Irradiation: Irradiating the polymer with light sources of different wavelengths or different light intensities, wherein the light source is selected from any one of a mercury lamp, LEDs with an emission wavelength of 313 nm to 425 nm, and LDI with an emission wavelength of 313 nm to 425 nm; S4. The polymerization conversion rate was studied by analyzing the changes in the characteristic peaks of the polymer obtained in S3 using an online infrared method.

7. The use of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator as claimed in claim 5, characterized in that: Follow the steps below to implement: S1. Ingredients: The mass fractions of monomer, water-soluble photoinitiator and auxiliary agent are as follows: Monomer: 100, Water-soluble photoinitiator: 1~1.5, Additives: 0-4.5; S2. Stirring: The monomer, water-soluble photoinitiator and auxiliary agent are mixed and stirred to fully dissolve the three to form a polymer; S3. Irradiation: Irradiating the polymer with light sources of different wavelengths or different light intensities, wherein the light source is selected from any one of a mercury lamp, LEDs with an emission wavelength of 313 nm to 425 nm, and LDI with an emission wavelength of 313 nm to 425 nm; S4. The polymerization conversion rate was studied by analyzing the changes in the characteristic peaks of the polymer obtained in S3 using an online infrared method.

8. The use of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator as claimed in claim 5, characterized in that: A water-soluble photoinitiator and a water-soluble monomer are dissolved in water to form a solution, and an LED light source with a wavelength of 365nm to 425nm is used to irradiate the solution. The solution absorbs single photons to stimulate polymerization or cross-linking of the water-soluble monomers, thereby preparing an antibacterial hydrogel system or water-based coating.

9. The use of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator as claimed in claim 5, characterized in that: Used to prepare a mixture for curing by light (ultraviolet light or visible light or LED light or equivalent light source), the formula of the mixture is as follows: Component I: contains at least one water-soluble photoinitiator described by general formula (i), and Component II: contains at least one free radical polymerizable compound containing an olefinic bond (C=C); Taking the total mass of the mixture as 100 parts, the mass fraction of component I is 0.01-30.

10. The use of the LED-sensitive styrylpyridinium salt-based ketoxime ester type water-soluble photoinitiator as claimed in claim 9, characterized in that: The mass fraction of component I is 0.5 to 10; Component II is selected from compounds or mixtures that are crosslinked by olefin free radical polymerization; component II is selected from monomers, oligomers or prepolymers, or aqueous dispersions of the monomers, oligomers or prepolymers, or mixtures or copolymers of at least two of the monomers, oligomers and prepolymers.

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