An oxime ester compound, a preparation method thereof, and applications thereof

Abstract

The present invention discloses an oxime ester compound, and the structural formula of the oxime ester compound is shown as formula (I); wherein, n, R1, R2, R3, R4, R5, R6, R7 are defined as in the specification. The present invention also discloses a preparation method of the above oxime ester compound. The present invention also discloses an application of the above oxime ester compound in a photoinitiator. The present invention also discloses a photocurable composition, and the photocurable composition contains at least one of the above oxime ester compounds. The oxime ester compound of the present invention does not generate gas during the photocuring process, and can effectively avoid the phenomenon that existing photoinitiators are prone to generate gas during curing, resulting in pores and uneven material on the surface of products such as coatings or films of polymer materials; moreover, the present invention has a wide spectral absorption range, strong absorption in the ultraviolet range, and good solubility.

Description

Technical Field

[0001] The present invention relates to the technical field of photoinitiators, and particularly relates to an oxime ester compound, a preparation method thereof, and an application thereof. Background Art

[0002] Photoinitiators play a crucial role in all photocurable formulations. In recent years, great attention has been paid to the development of new photoinitiators, which can be used in different fields, such as negative photoresists, liquid crystal displays (LCDs), dental materials, 3D fluorescence imaging, and food and beverages. Some traditional photoinitiators are widely produced and applied in the field of photocurable materials. However, these traditional photoinitiators exhibit problems such as low polymerization rate and conversion rate, low solubility in the system, oxygen inhibition of polymerization, and poor stability.

[0003] Oxime ester compounds improve their stability and sensitivity by introducing a large conjugated system, and are applied as effective type I photoinitiators. They have been widely used for a long time due to their photoactivity and use in free radical polymerization. However, the reported oxime ester compounds in existing research have problems such as poor visible light absorption, unstable properties, and high cost. At the same time, due to the generation of CO after the cleavage of the N-O bond and the decarboxylation of the acyloxy group in the oxime ester compound 2 When used as a photoinitiator, it is easy to cause bubbles and uneven material in products such as coatings and films after photocuring. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes an oxime ester compound, a preparation method thereof, and an application thereof; the oxime ester compound of the present invention does not generate gas during the photocuring process, and can effectively avoid the phenomenon that gas is easily generated during the curing of existing photoinitiators, resulting in pores and uneven material on the surface of products such as coatings or films of polymer materials; and the present invention has a wide spectral absorption range and strong absorption in the ultraviolet light range; and has better solubility.

[0005] The present invention proposes an oxime ester compound, and the structural formula of the oxime ester compound is shown in formula (I):

[0006]

[0007] Wherein, n is 0 or 1;

[0008] R 1 、R 2Each independently selected from hydrogen, linear or branched C1-C20 alkyl, C3-C10 cycloalkyl, C4-C10 cycloalkylalkyl, C4-C10 alkylcycloalkyl, C6-C20 aryl, C7-C20 aralkyl, C7-C20 alkylaryl, C3-C20 epoxyalkyl, C2-C20 alkenyl, wherein the aforementioned C1-C20 alkyl, C3-C10 cycloalkyl, C4-C10 cycloalkylalkyl, C4-C10 alkylcycloalkyl, C6-C20 aryl, C7-C20 aralkyl, C7-C20 alkylaryl, C3-C20 epoxyalkyl, C2-C20 alkenyl may each independently have one or more of the following substituents: C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy, halogen, nitro, amino, mono(C1-C6 alkyl)amino, di(C1-C6 alkyl)amino, mercapto; and R 1 and R 2 are not both hydrogen at the same time;

[0009] R 3 and R 4 and R 5 and R 6 and R 7 Each independently selected from one of hydrogen, halogen, nitro, trihalomethyl, cyano.

[0010] Preferably, R 1 and R 2 are each independently selected from one of hydrogen, methyl, phenyl; and R 1 and R 2 are not both hydrogen at the same time.

[0011] Preferably, when n is 0, R 1 is one of hydrogen, methyl, phenyl, and R 2 is one of methyl, phenyl.

[0012] Preferably, when n is 1, R 1 and R 2 are phenyl.

[0013] The present invention also provides a method for preparing the above-mentioned oxime ester compound, comprising the following steps: reacting substance A with substance B and a catalyst to obtain an oxime ester compound; the structural formula of substance A is shown in formula (II), and the structural formula of substance B is shown in formula (III);

[0014] wherein, X is halogen.

[0015] Preferably, the reaction temperature is -25 to -10 °C, and the reaction time is 4-8 h.

[0016] Preferably, the catalyst is at least one of triethylamine, pyridine, and dimethylaminopyridine.

[0017] Preferably, the molar ratio of substance B to the catalyst is 1:1.5 - 5.

[0018] Preferably, the reaction solvent is at least one of dichloromethane, chloroform, and tetrahydrofuran.

[0019] The present invention also provides an application of the above-mentioned oxime ester compound in a photoinitiator.

[0020] Preferably, the wavelength range of the light irradiation is 200 - 400 nm.

[0021] The present invention also provides a photocurable composition containing at least one of the above-mentioned oxime ester compounds.

[0022] Beneficial effects:

[0023] The oxime ester compound of the present invention does not generate gas during the photocuring process. Therefore, when used as a photoinitiator, it can effectively avoid the phenomenon that existing photoinitiators are prone to generate gas during photolysis, which easily causes pores and uneven material on the surface of products such as coatings or films of polymer materials.

[0024] Moreover, the oxime ester compound of the present invention has a large conjugated structure and a wide spectral absorption range, with strong absorption in the ultraviolet light range of 200 - 400 nm; it simultaneously generates free radicals under light irradiation and has high activity. The oxime ester compound of the present invention has a small molecule and has better solubility compared with other similar compounds, and has a wider applicable range. Description of the drawings

[0025] Figure 1 It is the ultraviolet-visible spectral diagram of Compound 1.

[0026] Figure 2 It is the proton nuclear magnetic resonance spectrum of Compound 1.

[0027] Figure 3 It is the proton nuclear magnetic resonance spectrum of Compound 2.

[0028] Figure 4 It is the proton nuclear magnetic resonance spectrum of Compound 3.

[0029] Figure 5 It is the proton nuclear magnetic resonance spectrum of Compound 4.

[0030] Figure 6 It is the carbon nuclear magnetic resonance spectrum of Compound 4.

[0031] Figure 7Photographs of the films prepared by photocuring of Compound 1-2 and Comparative Example 1. From left to right are Comparative Example 1, Compound 2, and Compound 1 in sequence.

[0032] Figure 8 Infrared double bond conversion rate curves of Compound 1-5 and Comparative Example 1 for catalytic olefin polymerization. Among them, a-e are Compound 1-5 in sequence, and f is Comparative Example 1.

[0033] Figure 9 Liquid phase mass spectrometry diagrams of Compound 1-4 under light source irradiation. Among them, a-d are Compound 1-4 in sequence. Detailed implementation mode

[0034] The present invention provides an oxime ester compound, and the structural formula of the oxime ester compound is shown in Formula (I):

[0035]

[0036] Wherein, n is 0 or 1;

[0037] R 1 、R 2 Are independently selected from one of hydrogen, linear or branched C1-C20 alkyl, C3-C10 cycloalkyl, C4-C10 cycloalkylalkyl, C4-C10 alkylcycloalkyl, C6-C20 aryl, C7-C20 aralkyl, C7-C20 alkylaryl, C3-C20 epoxyalkyl, C2-C20 alkenyl. Among them, the aforementioned C1-C20 alkyl, C3-C10 cycloalkyl, C4-C10 cycloalkylalkyl, C4-C10 alkylcycloalkyl, C6-C20 aryl, C7-C20 aralkyl, C7-C20 alkylaryl, C3-C20 epoxyalkyl, C2-C20 alkenyl may independently have one or more of the following substituents: C1-C6 alkyl, C1-C6 alkylthio, C1-C6 alkoxy, halogen, nitro, amino, mono(C1-C6 alkyl)amino, di(C1-C6 alkyl)amino, mercapto; and R 1 、R 2 Are not both hydrogen at the same time;

[0038] R 3 、R 4 、R 5 、R 6 、R 7 Are independently selected from one of hydrogen, halogen, nitro, trihalomethyl, and cyano.

[0039] Preferably, R 1 、R 2 Are independently selected from one of hydrogen, methyl, and phenyl; and R 1 、R 2 Are not both hydrogen at the same time.

[0040] Preferably, when n is 0, R 1 is one of hydrogen, methyl, and phenyl, and R 2 is one of methyl and phenyl.

[0041] Preferably, when n is 1, R 1 , R 2 is phenyl.

[0042] During photocuring, the N-O bond in the oxime ester compound shown in formula (I) breaks: the bond energy of the N-O bond in the oxime ester compound of the present invention is less than 49 kcal·mol -1 , while the C-C bond energy is generally greater than 300 kcal·mol -1 , and the breaking process always occurs at the weakest bond of the molecule; at the same time, due to the influence of the double bond connected to the carboxyl group, the generated electron delocalization effect further increases the C-C bond energy. Therefore, the carboxyl group is still connected to a specific conjugated structure, and the acyloxy group does not undergo decarboxylation and does not generate CO 2 gas. Therefore, when the oxime ester compound of the present invention is used as a photoinitiator, it can effectively avoid the phenomenon that the existing photoinitiator is prone to generate gas during curing, resulting in pores and uneven material on the surface of products such as coatings or films of polymer materials.

[0043] In addition, the oxime ester compound of the present invention has a large conjugated structure, a wide spectral absorption range, and strong absorption in the ultraviolet light range of 200 - 400 nm; it generates free radicals simultaneously under light irradiation and has high activity. The oxime ester compound of the present invention has a small molecule and has better solubility compared with other similar compounds (such as coumarin initiators), and has a wider applicable range.

[0044] In the present invention, "Cn-Cm" means that the number of carbon atoms contained in this group is n - m.

[0045] In the present invention, "Cn-Cm alkyl" refers to a straight-chain or branched saturated hydrocarbon group having n-m, for example 1-20, preferably 1-12, more preferably 1-8, particularly preferably 1-6, and especially preferably 1-4 carbon atoms, such as methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl and their isomers. C1-C8 alkyl can be methyl, ethyl, propyl, isopropyl, n-butyl, 2-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl and their isomers. C1-C6 alkyl can be methyl, ethyl, propyl, isopropyl, n-butyl, 2-butyl, tert-butyl, pentyl, isopentyl, hexyl and their isomers. C1-C4 alkyl can be methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl and their isomers.

[0046] In the present invention, "C3-Cm cycloalkyl" refers to a saturated alicyclic monocyclic group having 3-m, for example 3-20, preferably 3-8, and more preferably 5-6 ring carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl.

[0047] In the present invention, "C4-Cm cycloalkylalkyl" means an alkyl group substituted by a cycloalkyl group and containing a total of 4-m, for example 4-20, preferably 4-10, and more preferably 4-6 carbon atoms, where the alkyl and cycloalkyl groups are as defined herein, such as cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclopropylbutyl, cyclobutylmethyl, cyclobutylethyl, cyclopropylpropyl, cyclopropylbutyl, cyclopentylmethyl, cyclopentylethyl, cyclopropylpropyl, cyclopropylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylpropyl, cyclohexylbutyl, etc.

[0048] In the present invention, "C4-C10 alkylcycloalkyl" means a cycloalkyl substituted by an alkyl group and containing a total of 4-m carbon atoms, for example, 4-10 carbon atoms, preferably 4-8 carbon atoms, more preferably 4-6 carbon atoms, where the alkyl group and the cycloalkyl group are as defined herein, such as methylcyclopropyl, ethylcyclopropyl, propylcyclopropyl, butylcyclopropyl, methylcyclobutyl, ethylcyclobutyl, propylcyclobutyl, butylcyclobutyl, methylcyclopentyl, ethylcyclopentyl, propylcyclopentyl, butylcyclopentyl, methylcyclohexyl, ethylcyclohexyl, propylcyclohexyl, butylcyclohexyl, etc.

[0049] In the present invention, "C6-Cm aryl" refers to a monocyclic, bicyclic or tricyclic aromatic hydrocarbon group containing 6-m carbon atoms, for example, 6-18, preferably 6-10 carbon atoms. As examples of C6-Cm aryl, mention may be made of phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, xylyl, methylethylphenyl, diethylphenyl and naphthyl, etc.; preferably phenyl.

[0050] In the present invention, "C7-C20 aralkyl" means an alkyl group substituted by an aryl group and containing a total of 7-20 carbon atoms, for example, 7-12, preferably 7-10 carbon atoms, more preferably 7-8 carbon atoms, where the alkyl group and the aryl group are as defined herein, such as benzyl, phenethyl, naphthylmethyl, naphthylethyl, etc.

[0051] In the present invention, "C7-C20 alkylaryl" means an aryl group substituted by an alkyl group and containing a total of 7-20 carbon atoms, for example, 7-12, preferably 7-10 carbon atoms, more preferably 7-8 carbon atoms, where the alkyl group and the aryl group are as defined herein, such as methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, triethylphenyl, methylnaphthyl, ethylnaphthyl, etc.

[0052] In the present invention, "C3-C20 epoxyalkyl" refers to an alkyl group substituted by an epoxy group and containing a total of 3-20 carbon atoms, such as epoxypropyl, epoxybutyl, etc.

[0053] In the present invention, "C2-C20 alkenyl" refers to a straight-chain or branched olefinic group having 2-20 carbon atoms, such as vinyl, propenyl, butenyl, methacrylyl, pentenyl, methylbutenyl, etc.

[0054] In the present invention, "Cn-Cm alkoxy" and "Cn-Cm alkylthio" refer to Cn-Cm alkyl groups in which an oxygen atom or a sulfur atom is bonded to any carbon atom of the corresponding open-chain Cn-Cm alkane of Cn-Cm alkyl as a linking group, such as C1-C20 alkoxy (or thio) groups, preferably C1-C12 alkoxy (or thio) groups, more preferably C1-C8 alkoxy (or thio) groups, particularly preferably C1-C6 alkoxy (or thio) groups, and especially preferably C1-C4 alkoxy (or thio) groups. C1-C8 alkoxy groups can be methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, 2-butoxy, tert-butoxy, pentyloxy, isopentyloxy, hexyloxy, heptyloxy, octyloxy, isooctyloxy and their isomers. C1-C4 alkoxy groups can be methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy and their isomers. C1-C8 alkylthio groups can be methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, 2-butylthio, tert-butylthio, pentylthio, isopentylthio, hexylthio, heptylthio, octylthio, isooctylthio and their isomers. C1-C4 alkylthio groups can be methylthio, ethylthio, propylthio, isopropylthio, n-butylthio and their isomers.

[0055] The present invention also provides a method for preparing the above-mentioned oxime ester compound, which comprises the following steps: reacting substance A with substance B and a catalyst to obtain an oxime ester compound; the structural formula of substance A is shown in formula (II), and the structural formula of substance B is shown in formula (III);

[0056] wherein, X is a halogen.

[0057] Halogen refers to fluorine, chlorine, bromine or iodine; preferably X is chlorine or bromine.

[0058] Preferably, the reaction temperature is -25 to -10 °C, and the reaction time is 4 - 8 h.

[0059] Preferably, the catalyst is at least one of triethylamine, pyridine, and dimethylaminopyridine.

[0060] Preferably, the molar ratio of substance B to the catalyst is 1:1.5 - 5.

[0061] Preferably, the reaction solvent is at least one of dichloromethane, chloroform, and tetrahydrofuran.

[0062] After the above esterification reaction, the reaction solution is subjected to column chromatography purification to obtain an oxime ester compound, wherein the eluent is a mixed solvent of petroleum ether and ethyl acetate; preferably, the volume ratio of petroleum ether to ethyl acetate is 1:1.5 - 2.5; more preferably, the volume ratio is 1:2.

[0063] The amount of the reaction solvent is not limited, as long as Substance A and Substance B can be dissolved.

[0064] The reaction solvent dissolving Substance A can be mixed with the reaction solvent dissolving Substance B.

[0065] When dissolving Substance B, 20 - 30 mL of the reaction solvent is used to dissolve every 1 g of Substance B.

[0066] After being diluted with the reaction solvent, the catalyst is added to the reaction solvent containing Substance A and Substance B and mixed evenly.

[0067] The above Substance A can be prepared by the acylation reaction of Substance C, and the structural formula of Substance C is shown in Formula (Ⅳ):

[0068] R in Formulas (II), (III), and (Ⅳ) 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 are as defined above.

[0069] The specific preparation steps of Substance A include: in the presence of a catalyst, Substance C and an acylating reagent undergo an acylation reaction to obtain Substance A.

[0070] In the preparation process of Substance A, the acylating reagent is at least one of thionyl chloride, oxalyl chloride, and phosphorus trichloride.

[0071] In the preparation process of Substance A, the reaction solvent is at least one of dichloromethane, chloroform, and tetrahydrofuran.

[0072] In the preparation process of Substance A, the molar ratio of Substance C to the acylating reagent is 1:6 - 50; preferably 1:10.

[0073] In the preparation process of Substance A, the temperature of the acylation reaction is 30 - 40 °C, and the reaction is carried out in the dark for 7 - 10 h.

[0074] In the preparation process of Substance A, the catalyst is N,N - dimethylformamide.

[0075] In the preparation process of Substance A, the molar ratio of Substance C to the catalyst is 1:0.01 - 0.1; preferably 1:0.06.

[0076] In the preparation process of substance A, thin-layer chromatography can be used to detect whether the reaction is completed. The specific steps are as follows: take the reaction solution, add anhydrous methanol to quench the reaction, spot the reaction solution on a thin-layer chromatography plate and develop it (the developing agent is ethyl acetate and petroleum ether with a volume ratio of 2:1), and use ultraviolet light irradiation for color development; when the Rf value of substance C is less than 0.1 and the Rf value of substance A is greater than 0.7, the reaction is completed.

[0077] The present invention also provides the use of the above-mentioned oxime ester compound as a photoinitiator.

[0078] Preferably, the wavelength range of the light irradiation is 200 - 400 nm; more preferably, the wavelength of the light irradiation is 365 nm.

[0079] The oxime ester compound of the present invention can be used as a photoinitiator or photosensitizer in the fields of coatings, inks, microelectronics, printing, photoresists, liquid crystal displays, dental materials, 3D fluorescence imaging, etc. When used as a photoinitiator or photosensitizer, its dosage is conventional or can be determined through routine preliminary tests.

[0080] The present invention also provides a photocurable composition containing at least one of the above-mentioned oxime ester compounds.

[0081] In the photocurable composition, in addition to the oxime ester compound of the present invention, a photocurable resin is further included.

[0082] In the photocurable composition, the dosage of the oxime ester compound of the present invention can be 0.1 - 10 mol%, more preferably 0.5, 1, 2, 3, 4, 5 mol%. Here, the dosage of the oxime ester compound is calculated based on the total molar amount of the photocurable resin and the oxime ester compound.

[0083] The photocurable resin refers to an oligomer or prepolymer containing unsaturated carbon-carbon double bonds. After being irradiated with light, the oligomer or prepolymer can be polymerized by a photoinitiator and then crosslinked and cured. The photocurable resin is the main component of photocurable products (such as UV coatings, UV inks, UV adhesives, etc.).

[0084] The photocurable resin can be epoxy (meth)acrylate resin, polyester (meth)acrylate, polyurethane (meth)acrylate, ethylenically unsaturated polyester, amino (meth)acrylate resin, photoimageable alkali-soluble resin, etc.; preferably, the photocurable resin is polyester (meth)acrylate, such as a resin with trimethylolpropane triacrylate as the monomer.

[0085] Next, the technical solutions of the present invention will be described in detail through specific examples.

[0086] Example 1 (Preparation of Compound 1)

[0087] The structural formula of Compound 1 is as follows:

[0088]

[0089] The preparation method of Compound 1 includes the following steps:

[0090] Dissolve 1 mmol of coumarin-3-carboxylic acid in 5 mL of dry dichloromethane, add 10 mmol of thionyl chloride (thionyl chloride is volatile, calculated by the amount at the time of weighing) and 0.05 mL (0.6 mmol) of N,N-dimethylformamide, adjust the temperature to 35 °C, stir and reflux for 7 h, and use thin-layer chromatography to detect whether the reaction is completed. The specific steps are as follows: Use a capillary tube to take the reaction solution, add 1 drop of anhydrous methanol to quench the reaction, spot the reaction solution on a thin-layer chromatography plate and run the sample (the developing agent is ethyl acetate and petroleum ether with a volume ratio of 2:1), and then use ultraviolet light irradiation for color development; when the Rf value of coumarin-3-carboxylic acid is less than 0.1 and the Rf value of coumarin-3-carbonyl chloride is greater than 0.7, the reaction ends. Under water-free conditions, evaporate the dichloromethane of the reaction solution to dryness to obtain coumarin-3-carbonyl chloride;

[0091] Dissolve 1 mmol of coumarin-3-carbonyl chloride in dry dichloromethane, and gradually add it dropwise to a 2.4 mL dichloromethane solution containing 1 mmol of benzaldehyde oxime using a constant pressure funnel, and then gradually add a diluted solution containing 1.5 mmol of triethylamine (1 mL of triethylamine is diluted with 5 mL of dry dichloromethane). In an ice-water bath at a temperature of -25 to -10 °C, stir and react for 6 h. Take the reaction solution to be concentrated, and then perform column chromatography treatment (the eluent is a mixed solvent of petroleum ether and ethyl acetate with a volume ratio of 1:2), collect the eluent, rotate and evaporate to remove the solvent, and dry to obtain Compound 1.

[0092] The ultraviolet-visible spectrum of Compound 1 is as Figure 1 shown, and the data are shown in Figure 1 ; It can be seen from Figure 1 that Compound 1 has a strong absorption in the range of 200 - 400 nm, the main absorption peak is located at about 300 nm, and the peak tail extends to 400 nm, and it can efficiently absorb the energy of the commercially available mainstream 360 nm LED light source.

[0093] The proton nuclear magnetic resonance spectrum of Compound 1 is as Figure 2 shown; among them, 1 H NMR(400MHz,Chloroform-d)δ8.06(s,1H),7.94–7.88(m,2H),7.66–7.42(m,7H),7.21(s,1H).

[0094] Example 2 (Preparation of Compound 2)

[0095] Replace "1 mmol of benzaldehyde oxime" with "1 mmol of acetophenone oxime", and keep the other conditions the same as in Example 1 to obtain Compound 2. The structural formula of Compound 2 is as follows:

[0096]

[0097] The 1H NMR spectrum of Compound 2 is as shown in Figure 3 ; among which, 1 H NMR(400 MHz, Chloroform-d)δ8.73(s, 1H), 7.85–7.33(m, 10H), 2.60(s, 3H).

[0098] Example 3 (Preparation of Compound 3)

[0099] Replace "1 mmol of benzaldehyde oxime" with "1 mmol of acetone oxime", and keep the other conditions the same as in Example 1 to obtain Compound 3. The structural formula of Compound 3 is as follows:

[0100]

[0101] The 1H NMR spectrum of Compound 3 is as shown in Figure 4 ; among which, 1 H NMR(400 MHz, Chloroform-d)δ8.70(s, 1H), 7.71–7.31(m, 4H), 2.21(s, 3H), 2.13(s, 3H).

[0102] Example 4 (Preparation of Compound 4)

[0103] Replace "1 mmol of benzaldehyde oxime" with "1 mmol of benzophenone oxime", and use a mixed solvent of petroleum ether and ethyl acetate as the eluent for gradient elution (for the mixed solvent of petroleum ether and ethyl acetate as the eluent, first use a petroleum ether and ethyl acetate with a volume ratio of 1:1 to wash away the front band, and then use a petroleum ether and ethyl acetate with a volume ratio of 1:2 to wash to obtain the middle band Compound 4), and keep the other conditions the same as in Example 1 to obtain Compound 4. The structural formula of Compound 4 is as follows:

[0104]

[0105] The 1H NMR spectrum of Compound 4 is as shown in Figure 5 ; among which, 1 H NMR(400 MHz, Chloroform-d)δ8.33(s, 1H), 7.67–7.61(m, 3H), 7.52 - 7.47(m, 7H), 7.43 - 7.38(m, 2H), 7.31(t, J=5.6 Hz, 2H).

[0106] The 13C NMR spectrum of Compound 4 is shown inFigure 6 ; wherein, 13 C NMR (101 MHz, CDCl 3 ) δ 166.40, 161.05, 156.04, 155.23, 151.51, 149.22, 135.78, 134.56, 134.53, 132.29, 131.15, 130.51, 129.94, 129.58, 129.32, 128.47, 128.19, 126.27, 124.86, 117.82, 117.44, 117.24, 166.82.

[0107] Example 5 (Preparation of Compound 5)

[0108] Replace "1 mmol of coumarin-3-carboxylic acid" with "1 mmol of coumarin-3-acetic acid", and the others are the same as in Example 4 to obtain Compound 5. The structural formula of Compound 5 is as follows:

[0109]

[0110] The proton nuclear magnetic resonance spectrum of Compound 5 is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 8.12 (s, 1H), 7.65–7.60 (m, 3H), 7.51 - 7.43 (m, 7H), 7.39 - 7.37 (m, 2H), 7.30 (s, 2H), 3.20 (s, 2H).

[0111] Comparative Example 1

[0112] The structural formula of Comparative Example 1 is shown as follows:

[0113] It can be prepared according to the method described in the literature (Zhu Guigang, Synthesis of Coumarin-based Oxime Ester Derivatives and Their Applications in LED Photocuring [D], 2016, Jiangnan University).

[0114] Test 1

[0115] Accurately weigh 280 mg (99 mol%) of trimethylolpropane triacrylate and mix it with Compounds 1-2 and Comparative Example 1 (the addition amounts are both 1 mol%) respectively, and ultrasonicate for 10 min to dissolve and mix evenly to obtain a mixture.

[0116] Scrape the above mixture onto the surface of a glass slide, and control the film thickness to be about 0.5 mm; use a Fusion UV photocuring system (365 nm light source, average power controlled below 1000 mW), irradiate for 5 s to cause curing, and observe the state of the film surface. The results are as Figure 7 shown, Figure 7Photographs of the films prepared by photocuring of Compound 1-2 and Comparative Example 1. From left to right, they are Comparative Example 1, Compound 2, and Compound 1 respectively.

[0117] It can be seen from Figure 7 that there are no bubbles and no gas generation on the surface of the film prepared by photocuring of Compound 1-2. In Comparative Example 1, pores are generated during light curing, and the cured film is cracked into fragments under the combined action of curing shrinkage stress and pores.

[0118] Test 2

[0119] Accurately weigh 280 mg (99 mol%) of trimethylolpropane triacrylate and mix it with Compound 1-5 and Comparative Example 1 (the addition amount is 1 mol% for each) respectively. Ultrasonic for 10 min to dissolve and mix evenly to obtain a mixture.

[0120] Drop the above mixture onto the surface of a KBr salt plate, control the film thickness to about 0.5 mm, use a Fusion UV photocuring system (365 nm light source, average power controlled below 1000 mW), irradiate for 60 s, control the light source intensity to 25 mw / cm 2 , and use a Nicolet IS50 FT-IR infrared spectrometer to monitor the reaction process in real time. The results are as Figure 8 shown. Figure 8 It is a graph of the infrared double bond conversion rate of Compound 1-5 and Comparative Example 1 catalyzing olefin polymerization. Among them, a-e are Compound 1-5 in turn, and f is Comparative Example 1; it can be seen from Figure 8 that during the film formation process of Compound 1-5 and Comparative Example 1, the double bond conversion rates are 86%, 88%, 64%, 73%, 81%, and 63% in turn.

[0121] Test 3

[0122] Take Compound 1-4, place it under a 365 nm light source for irradiation, and perform liquid phase mass spectrometry detection. The typical spectrum is as Figure 9 shown. Figure 9 It is the liquid phase mass spectrometry diagram of Compound 1-4 under light source irradiation. Among them, a-d are Compound 1-4 in turn. It can be seen from Figure 9 that the carboxyl group in the photolysis product of Compound 1-4 is still on the cleaved coumarin ring and has not decomposed, indicating that no gas is generated during the photocuring process of Compound 1-4; while it has been recorded in the literature (Zhu Guigang, Synthesis of Coumarin-based Oxime Ester Derivatives and Their Applications in LED Photocuring [D], 2016, Jiangnan University) that gas is generated during the photocuring process of Comparative Example 1.

[0123] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, making equivalent substitutions or changes should be covered by the protection scope of the present invention.

Claims

1. An oxime ester compound, characterized in that, the structural formula of the oxime ester compound is shown as formula (I): wherein, n is 0 or 1; R 1 is one of hydrogen, methyl, and phenyl; R 2 is phenyl; R 3 、R 4 、R 5 、R 6 、R 7 Each independently selected from one of hydrogen, halogen, nitro, trihalomethyl, and cyano.

2. The oxime ester compound according to claim 1, characterized in that, When n is 1, R 1 , R 2 is phenyl.

3. A method for preparing the oxime ester compound according to claim 1 or 2, characterized in that, it comprises the following steps: taking substance A, substance B and a catalyst to carry out an esterification reaction to obtain the oxime ester compound; the structural formula of substance A is shown as formula (II), and the structural formula of substance B is shown as formula (III); Wherein, X is a halogen.

4. The method for preparing the oxime ester compound according to claim 3, characterized in that, the reaction temperature is -25 to -10 °C, and the reaction time is 4 - 8 h.

5. The method for preparing the oxime ester compound according to claim 3, characterized in that, the catalyst is at least one of triethylamine, pyridine, and dimethylaminopyridine.

6. The method for preparing the oxime ester compound according to claim 3, characterized in that, the molar ratio of substance B to the catalyst is 1:1.5 - 5.

7. The method for preparing the oxime ester compound according to claim 3, characterized in that, the reaction solvent is at least one of dichloromethane, chloroform, and tetrahydrofuran.

8. The application of the oxime ester compound according to claim 1 or 2 in a photoinitiator.

9. The application of the oxime ester compound according to claim 8 in a photoinitiator, characterized in that, the wavelength range of the light irradiation is 200 - 400 nm.

10. A photocurable composition, characterized in that, the photocurable composition contains at least one oxime ester compound according to claim 1 or 2.

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