Aromatic acyl formate oxime ester photoinitiator, and preparation method therefor

Abstract

The present invention relates to an aromatic acyl formate oxime ester photoinitiator suitable for LED photopolymerization. The photoinitiator has a structure represented by general formula (I), wherein Ar, R1 and R2 are as defined in the description and claims. The present invention also relates to a preparation method for the photoinitiator and a use thereof in an LED photopolymerization system.

Description

Arylformyl oxime photoinitiators and their preparation methods Technical Field

[0001] This invention relates to an arbutin oxime photoinitiator suitable for LED photocuring, its preparation method, and its application in photocuring using an LED light source. Background Technology

[0002] LED photopolymerization (also known as LED curing or LED photopolymerization) is attracting increasing attention in the field of photosensitive polymers. Photoinitiators that match the wavelength of the LED light source (also known as LED photoinitiators) are one of the important factors affecting the applicability of LED photopolymerization technology. To date, most reported LED photoinitiators contain large conjugated structures (chromophores) in their structure. While these large conjugated structures provide good light absorption, they also impart color to the cured system due to the absorption of visible light. Darker colors hinder light from penetrating the cured system to its deeper layers, which undoubtedly limits the application of such LED photoinitiators in photopolymerization systems requiring colorless curing or deep curing.

[0003] Currently, the main approach to solving these problems is to develop LED photoinitiators with photobleaching properties. These photoinitiators can undergo degradation at specific wavelengths, and the resulting fragments do not absorb in the visible light region, thus yielding a colorless cured product. However, a drawback of these photoinitiators is that they are difficult to completely degrade in the curing system, especially for systems requiring deep curing, where the color imparted by the photoinitiator is difficult to completely disappear. Summary of the Invention

[0004] The purpose of this invention is to provide a photoinitiator that can effectively generate active free radicals that initiate polymerization and / or crosslinking reactions at the emission wavelengths of commonly used LED light sources (e.g., 385nm, 405nm, 455nm), but at the same time has no absorption or very low absorption of visible light.

[0005] The inventors of this invention were surprised to discover that the aforementioned objective is achieved through an oxime ester compound with an α-dicarbonyl structure. This compound exhibits appropriate weak absorption in the visible light region, such a degree of absorption leading to effective photolysis and the generation of active free radicals without imparting color to the cured system. Furthermore, some oxime ester compounds containing an α-dicarbonyl structure even possess initiation properties at high wavelengths (e.g., 455 nm), enabling a wider range of applications. Moreover, the preparation of the oxime ester photoinitiator with an α-dicarbonyl structure of this invention does not require noble metal catalysis or harsh conditions, and exhibits excellent performance, thus possessing significant application value.

[0006] In a first aspect, the present invention provides an arbutin oxime compound having the structure shown in formula (I):

[0007] in,

[0008] Ar is C6-C 10 -Aryl or C6-C substituted with at least one group selected from the group consisting of aryl groups or groups ... 10 -Aryl: Halogen, Nitro, Hydroxyl, Thiol, Amino, C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 -Substitution of aryl groups;

[0009] R1 and R2 are independently selected from hydrogen, Q, and C1-C. 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -cycloalkyl, the aforementioned C1-C 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -The cycloalkyl group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 The alkyl)amino group is substituted, wherein

[0010] R1 and R2 cannot be either hydrogen or Q at the same time.

[0011] Q is a coumarin group or coumarin ketone group having the structure shown in formula (II):

[0012] Among them, R3, R4, R5, R6, and R7 are independently selected from hydrogen, halogen, nitro, hydroxyl, mercapto, amino, and C1-C. 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 - Aryl group substitution,

[0013] n is 0 or 1, and

[0014] * indicates the position where group Q is connected to other structural parts.

[0015] In a second aspect, the present invention provides a method for preparing the arbutin oxime ester compound represented by formula (I) above, the method comprising esterifying the arbutinic acid represented by formula (III) with the oxime represented by formula (IV):

[0016] In Equation (III), Ar and in Equation (IV), R1 and R2 have the same meaning as Ar, R1 and R2 in Equation (I), respectively.

[0017] In a third aspect, the present invention provides a composition for LED photocuring, the composition comprising:

[0018] - At least one of the arbutin oxime compounds represented by formula (I) above is used as a photoinitiator, and

[0019] - A photocurable component, selected from at least one of monomers, oligomers, and prepolymers having olefinic unsaturated functional groups.

[0020] The mass ratio of the photoinitiator to the photocurable component is in the range of 0.2:100 to 6:100.

[0021] In a fourth aspect, the present invention provides the use of the arbutin oxime compound represented by the aforementioned formula (I) as a photoinitiator in an LED photocuring system. Attached Figure Description

[0022] Figure 1 schematically illustrates the polymerization process initiated by the arbutin oxime compound according to the present invention as a photoinitiator;

[0023] Figure 2 shows the UV absorption spectra of acetone benzoylformate (AOXE), acetone benzoylformate (F-AOXE), acetone benzoylformate (Cl-AOXE), and acetone benzoylformate (O-AOXE) prepared according to Examples 1 to 4 in the range of 200 nm to 450 nm. The small image in the upper right corner is a partial screenshot of the UV absorption spectrum in the range of 360 nm to 440 nm.

[0024] Figure 3 shows the UV absorption spectra of coumarin benzoylcarbamate (COXE), coumarin p-fluorobenzoylcarbamate (F-COXE), coumarin p-chlorobenzoylcarbamate (Cl-COXE), and coumarin p-methoxybenzoylcarbamate (O-COXE) prepared according to Examples 5 to 8 in the range of 200 nm to 500 nm. The small image in the upper right corner is a partial screenshot of the UV absorption spectrum in the range of 430 nm to 470 nm.

[0025] Figure 4 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate polymerization initiated by AOXE, F-AOXE, Cl-AOXE and O-AOXE prepared according to Examples 1 to 4 and the commercially available photoinitiator OXE-01 under a 385nm LED light source.

[0026] Figure 5 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate polymerization initiated by AOXE, F-AOXE, Cl-AOXE and O-AOXE prepared according to Examples 1 to 4 and the commercially available photoinitiator OXE-01 under a 405 nm LED light source.

[0027] Figure 6 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate initiated by COXE, F-COXE, Cl-COXE and O-COXE prepared according to Examples 5 to 8 and the commercially available photoinitiator OXE-01 under a 405 nm LED light source.

[0028] Figure 7 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate initiated by COXE, F-COXE, Cl-COXE and O-COXE prepared according to Examples 5 to 8 and the commercially available photoinitiator OXE-01 under a 455 nm LED light source.

[0029] Figure 8 shows a comparison between F-AOXE prepared according to Example 2 and the deep polymerization of monomer tripropylene glycol diacrylate initiated by the commercially available photoinitiator OXE-01. Detailed Implementation

[0030] In this document, "halogen" refers to fluorine, chlorine, bromine, and iodine. In this invention, the halogen is preferably fluorine, chlorine, bromine, or a combination thereof, and particularly preferably fluorine or chlorine.

[0031] In this paper, the prefix "C" used in the definition of groups n -C m - "In each case, it indicates that the defined group contains n to m carbon atoms, where n and m are specifically mentioned numbers. For example, "C1-C 16 "-" indicates that the defined group has 1 to 16 carbon atoms. When the defined group has substituents, the number of carbon atoms "C" is... n -C m - "Excluding carbon atoms contained in substituents."

[0032] In this article, "C1-C 16 "-alkyl" refers to a straight-chain or branched alkyl group having 1 to 16 carbon atoms, such as C1-C1 alkyl. 12 -alkyl, preferably C1-C8-alkyl, more preferably C1-C6-alkyl, and especially preferably C1-C4-alkyl. More specific examples include, but are not limited to, methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, n-hexyl, 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, n-Heptyl, n-Octyl, 2-Ethylhexyl, n-Nonyl, n-Decyl and their isomers, etc. "C1-C 16 "-alkyl" is preferably C1-C6-alkyl, more preferably C1-C4-alkyl, such as methyl, ethyl, n-propyl, 1-methylethyl, n-butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl.

[0033] In this article, "C6-C 10 "-aryl" refers to monocyclic or bicyclic aromatic hydrocarbon groups containing 6-10 carbon atoms, such as phenyl, tolyl, ethylphenyl, propanylphenyl, butylphenyl, xylyl, methylethylphenyl, diethylphenyl, methylpropylphenyl, naphthyl and their isomers, etc. "C6-C" 10 The aryl group is preferably phenyl or naphthyl, and more preferably phenyl.

[0034] In this article, "C3-C 10 "-Cycloalkyl" refers to a saturated alicyclic group having 3-10 carbon atoms, preferably having a monocyclic structure, such as C3-C6-cycloalkyl, and more specifically cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and their isomers.

[0035] In this article, "C3-C 10 -cycloalkyl-C1-C 16 "-alkyl" indicates that it is formed by C3-C 10 -Cycloalkyl-substituted C1-C 16 -alkyl, wherein the alkyl group is attached to the rest of the compound via an alkyl structure. Here, "C3-C" 10 -cycloalkyl" and "C1-C 16 "-alkyl" has the meaning, preferred meaning, and specific examples described above. "C3-C" 10 -cycloalkyl-C1-C 16 "-alkyl" is preferably C3-C6-cycloalkyl-C1-C4-alkyl, and more specific examples include, but are not limited to, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclopropylbutyl, cyclobutylmethyl, cyclobutylethyl, cyclobutylpropyl, cyclobutylbutyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylpropyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylpropyl, cyclohexylbutyl and their isomers.

[0036] In this article, "C1-C 16 -alkyl-C3-C 10 "-cycloalkyl" indicates that it is C1-C 16 -alkyl-substituted -C3-C 10 -Cycloalkyl, wherein the cycloalkyl group is linked to the rest of the compound via a cycloalkyl structure. Here, "C1-C..." 16 -alkyl" and "C3-C" 10 "-cycloalkyl" has the meaning, preferred meaning, and specific examples described above. "C1-C 16 -alkyl-C3-C 10 "-Cycloalkyl" is preferably C1-C4-alkyl-C3-C6-cycloalkyl, and more specific examples include, but are not limited to, methylcyclopropyl, ethylcyclopropyl, propylcyclopropyl, butylcyclopropyl, methylcyclobutyl, ethylcyclobutyl, propylcyclobutyl, butylcyclobutyl, methylcyclopentyl, ethylcyclopentyl, propylcyclopentyl, butylcyclopentyl, methylcyclohexyl, ethylcyclohexyl, propylcyclohexyl, butylcyclohexyl and their isomers.

[0037] In this article, "C1-C 16 -alkoxy group and C1-C 16 "-alkylthio" refers to the group at C1-C2. 16-A group in which a hydrogen atom on any carbon atom of an alkane chain is replaced by an oxygen (-O-) or sulfur (-S-) atom, thereby connecting the alkane to the rest of the compound through that oxygen or sulfur atom. These two groups can also be represented as "C1-C". 16 -alkyl-O-" and "C1-C" 16 -alkyl-S-". Here "C1-C" 16 "alkyl" has the meaning, preferred meaning, and specific examples described above. "C1-C 16 "-alkoxy" is preferably a C1-C6 alkoxy, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, 2-butoxy, tert-butoxy, pentoxy, isopentoxy, hexoxy, and their isomers. "C1-C 16 "-alkylthio" is preferably C1-C6-alkylthio, which can be methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, 2-butylthio, tert-butylthio, pentylthio, isopentylthio, hexylthio and their isomers, etc.

[0038] In this article, "single (C1-C 16 "-alkyl)amino" refers to a substance with a C1-C1 group. 16 -Alkyl-substituted amino groups. "Di(C1-C 16 "-alkyl)amino" refers to a compound containing two C1-C2 groups. 16 -Alkyl-substituted amino group, wherein two C1-C 16 -The alkyl substituents can be the same or different. Here, "C1-C" 16 "-alkyl" has the meaning, preferred meaning, and specific examples described above.

[0039] In the following description of the invention, unless otherwise expressly stated, all numerical values ​​are to be regarded as being modified by the word "approximately". The inventors have reported the numerical values ​​in the embodiments as accurately as possible, although these values ​​inevitably include a certain degree of error.

[0040] In a first aspect, the present invention provides an arbutin oxime compound having the structure shown in formula (I):

[0041] in,

[0042] Ar is C6-C 10 -Aryl or C6-C substituted with at least one group selected from the group consisting of aryl groups or groups ... 10 -Aryl: Halogen, Nitro, Hydroxyl, Thiol, Amino, C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 -Substitution of aryl groups;

[0043] R1 and R2 are independently selected from hydrogen, Q, and C1-C. 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -cycloalkyl, the aforementioned C1-C 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -The cycloalkyl group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 The alkyl)amino group is substituted, wherein

[0044] R1 and R2 cannot be either hydrogen or Q at the same time.

[0045] Q is a coumarin group or coumarin ketone group having the structure shown in formula (II):

[0046] Among them, R3, R4, R5, R6, and R7 are independently selected from hydrogen, halogen, nitro, hydroxyl, mercapto, amino, and C1-C. 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16-alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 - Aryl group substitution,

[0047] n is 0 or 1, and

[0048] * indicates the position where group Q is connected to other structural parts.

[0049] In formula (1), Ar is, for example, an unsubstituted phenyl or naphthyl group or a group substituted with at least one group selected from the group consisting of: halogen, nitro, hydroxyl, mercapto, C1-C. 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -Alkylthio, the aforementioned C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -The alkylthio group is optionally selected from at least one group chosen from halogen, hydroxyl, mercapto, amino, and C6-C. 10 -Aromatic group substitution.

[0050] Ar, particularly unsubstituted or substituted phenyl or naphthyl groups selected from the group consisting of halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio groups are optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, and C6-C 10 -Aromatic group substitution.

[0051] Ar is preferably a phenyl group or a phenyl group substituted with at least one, preferably one, group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally substituted with at least one group selected from halogen, hydroxyl, and mercapto.

[0052] In some embodiments, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio. Preferably, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio.

[0053] For example, Ar is phenyl, p-fluorophenyl, p-chlorophenyl, p-methoxyphenyl, or p-ethoxyphenyl.

[0054] In equation (1), R1 and R2 are independently selected from hydrogen, Q, C1-C, for example. 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, the aforementioned C1-C 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C6. 12 -alkoxy group, C1-C 12 -alkylthio group, mono(C1-C) 12 -alkyl)amino and di(C1-C 12 Substitution of alkyl amino groups.

[0055] In any embodiment of the invention, R1 and R2 are not simultaneously hydrogen and either group Q as defined in the context. In other words, in any structure shown in formula (1), R1 and R2 are neither simultaneously hydrogen nor simultaneously group Q, as will not be repeated below.

[0056] In particular, R1 and R2 are independently selected from hydrogen, Q, C1-C8-alkyl or C1-C8-alkyl substituted with at least one group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C6-alkoxy and C1-C6-alkylthio.

[0057] In some embodiments, R1 is hydrogen or a C1-C6-alkyl, and R2 is a C1-C6-alkyl or Q. Preferably, R1 is a C1-C4-alkyl, such as methyl or ethyl, and R2 is a C1-C4-alkyl or Q, such as methyl or ethyl. It should be understood that when R1 and R2 are both C1-C6-alkyl or C1-C4-alkyl, they may be the same or different from each other.

[0058] Group Q is, for example, a coumarin group or a coumarin ketone group having the structure shown in formula (II):

[0059] in,

[0060] R3, R4, R5, R6, and R7 are independently selected from hydrogen, halogen, hydroxyl, mercapto, C1-C. 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -Alkylthio, the aforementioned C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12-The alkylthio group is optionally selected from at least one group chosen from halogen, nitro, hydroxyl, mercapto, amino, and C6-C. 10 - Aryl group substitution, and

[0061] n can be 0 or 1, preferably 0.

[0062] In any embodiment of the present invention, group Q is a coumarin group or coumarin ketone group having the structure shown in formula (II):

[0063] in,

[0064] R3, R5, R6, and R7 are hydrogen.

[0065] R4 is selected from halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and

[0066] n is 0.

[0067] Specifically, in the group Q shown in the aforementioned formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkoxy or C1-C6-alkylthio, and n is 0.

[0068] More specifically, in the group Q represented by formula (II) above, R3, R5, R6, and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy, or C1-C4-alkylthio, and n is 0. Preferably, in the group Q represented by formula (II) above, R3, R5, R6, and R7 are hydrogen, R4 is selected from C1-C4-alkoxy or C1-C4-alkylthio, such as methoxy or ethoxy, and n is 0.

[0069] In an exemplary embodiment of the first aspect of the invention, the arbutin oxime compound has the structure shown in formula (I):

[0070] in,

[0071] Ar is a phenyl group or a phenyl group substituted with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio.

[0072] R1 is hydrogen or C1-C6-alkyl.

[0073] R2 is a C1-C6-alkyl group or Q, wherein the group Q is a coumarin group having the structure shown in formula (II):

[0074] in,

[0075] R3, R5, R6, and R7 are hydrogen.

[0076] R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and

[0077] n is 0.

[0078] According to the foregoing exemplary embodiments, the arbutin oxime compound more preferably has the structure shown in formula (I):

[0079] in,

[0080] Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio.

[0081] R1 is hydrogen or a C1-C4-alkyl group.

[0082] R2 is a C1-C4-alkyl group or Q, wherein the group Q is a coumarin group having the structure shown in formula (II):

[0083] in,

[0084] R3, R5, R6, and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy, or C1-C4-alkylthio, and n is 0.

[0085] According to the foregoing exemplary embodiments, the arbutin oxime compound more preferably has the structure shown in formula (I):

[0086] in,

[0087] Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of fluorine, chlorine, C1-C4-alkoxy, and C1-C4-alkylthio.

[0088] R1 is a C1-C4-alkyl group.

[0089] R2 is a C1-C4-alkyl group or Q, wherein the group Q is a coumarin group having the structure shown in formula (II):

[0090] in,

[0091] R3, R5, R6, and R7 are hydrogen, R4 is selected from C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

[0092] According to the foregoing exemplary embodiments, the arbutin oxime ester compound is particularly preferably having the structure shown in formula (I):

[0093] in,

[0094] Ar is phenyl, p-fluorophenyl, p-chlorophenyl, p-methoxyphenyl, or p-ethoxyphenyl.

[0095] R1 is methyl or ethyl.

[0096] R2 is methyl, ethyl, or Q, wherein the group Q is a coumarin group having the structure shown in formula (II):

[0097] in

[0098] R3, R5, R6, and R7 are hydrogen, R4 is selected from methoxy, ethoxy, methylthio, or ethylthio, and n is 0.

[0099] More specifically, the present invention relates to arbutin oxime compounds having the structure shown in formula (I), wherein formula (I) is as described in any of the foregoing embodiments, and wherein neither R1 nor R2 is Q.

[0100] Furthermore, the present invention also relates to arbutin oxime compounds having the structure shown in formula (I), wherein formula (I) is as described in any of the foregoing embodiments, and wherein R2 is Q.

[0101] In compounds of formula (I), the oxime ester group may exist in two configurations, namely the (Z) type or the (E) type. Isomers can be isolated by conventional methods, but mixtures of isomers can also be used as photoinitiators. Unless otherwise specified, the arethaneylformate oxime compounds of formula (I) herein encompass any of the aforementioned configurations as well as mixtures of isomers of both configurations.

[0102] In a second aspect, the present invention provides a method for preparing the arbutin oxime ester compound represented by formula (I) above, the method comprising esterifying the arbutinic acid represented by formula (III) with the oxime represented by formula (IV):

[0103] In Equation (III), Ar and in Equation (IV), R1 and R2 have the same meaning as Ar, R1 and R2 in Equation (I), respectively.

[0104] The esterification reaction between the arethanecarboxylic acid shown in formula (III) and the oxime shown in formula (IV) can be carried out in a manner known in the art. Through this esterification reaction, the carboxyl group in formula (III) condenses with the hydroxyl group in formula (IV) to form an ester group, thereby obtaining the compound of formula (I). In this esterification reaction, there is no particular limitation on the relative amounts of the arethanecarboxylic acid shown in formula (III) and the oxime shown in formula (IV), for example, they can be used in a molar ratio of 1:1.5 to 1.5:1, preferably 1:1.2 to 1.2:1, for example, 1:1.

[0105] The esterification reaction between the arylformic acid shown in formula (III) and the oxime shown in formula (IV) is generally carried out in the presence of a base. The base is, for example, an organic base, particularly a nitrogen-containing organic base. As a non-limiting example of the base, at least one selected from the group consisting of: pyridine, alkyl-substituted pyridines such as 2-methylpyridine, 3-methylpyridine and 4-dimethylaminopyridine, dialkylamines such as diethylamine, and trialkylamines such as triethylamine.

[0106] Preferably, the base is selected from at least one of the following groups: pyridine, 2-methylpyridine, 3-methylpyridine, 4-dimethylaminopyridine, diethylamine and triethylamine, more preferably from at least one of the following groups: pyridine, 2-methylpyridine, 3-methylpyridine and 4-dimethylaminopyridine.

[0107] Bases are typically used in catalytic amounts. Although bases can also be used in equimolar amounts, in excess amounts, or in solvent amounts, catalytic amounts are preferred. The catalytic amount can be determined based on common knowledge in the art or through routine preliminary experiments, referring to the examples given herein. For example, the base is used with the arylformic acid of formula (III) in the following molar ratio: 0.01:1 to 0.5:1, preferably 0.05:1 to 0.2:1, more preferably 0.1:1.

[0108] The esterification reaction between the arethanecarboxylic acid shown in formula (III) and the oxime shown in formula (IV) can be carried out under conditions of water removal. This can be done, for example, by distillation / condensation.

[0109] Preferably, the esterification reaction can be carried out under a dehydrating agent. The choice of dehydrating agent is not particularly limited, but organic dehydrating agents are preferred. As non-limiting examples of dehydrating agents, at least one selected from the group consisting of: dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide, and 1,1'-carbonylbis-1H-imidazole.

[0110] The dehydrating agent can be used in conventional amounts, such as in equimolar amounts with the reactants, and preferably in appropriate excess amounts. For example, the dehydrating agent is used with the arylformic acid shown in formula (III) in the following molar ratio: 1.5:1 to 1:1, preferably 1.2:1 to 1:1, more preferably 1.2:1.

[0111] The esterification reaction between the arylformic acid shown in formula (III) and the oxime shown in formula (IV) is generally carried out in a solvent, preferably an organic solvent. There are no particular limitations on the choice of solvent, for example, at least one of tetrahydrofuran, benzene, toluene, ethyl acetate, N,N-dimethylformamide, dichloromethane and acetone can be used.

[0112] The esterification reaction can be carried out over a very wide temperature range. Advantageously, according to the invention, the esterification reaction is carried out at a temperature of -10°C to 150°C, preferably 0°C to 100°C, and most preferably at room temperature.

[0113] After the esterification reaction is complete, a mixture of products containing compound (I) is obtained. This mixture of products can be post-processed by any separation and purification method known in the art, such as filtration, drying, distillation, recrystallization, chromatography, etc.

[0114] The reactants of the aforementioned esterification reaction, namely, the arylformic acid represented by formula (III) and the oxime represented by formula (IV), can be synthesized or obtained commercially by methods known in the art, without any particular limitation.

[0115] In some embodiments of the method of the present invention, the arylformic acid represented by formula (III) is prepared, for example, by Friedel-Crafts acylation, comprising: reacting the aromatic hydrocarbon Ar-H corresponding to the Ar group in formula (III) with a chloroformyl ester in the presence of a Lewis acid (such as aluminum chloride) to obtain the arylformyl ester, followed by hydrolysis to obtain the corresponding arylformic acid. The chloroformyl ester is used as an acylation agent and may be, for example, methyl chloroformate (i.e., monomethyl oxaloyl chloride) or ethyl chloroformate (i.e., monoethyl oxaloyl chloride). There is no particular limitation on the relative amounts of the aromatic hydrocarbon Ar-H and the chloroformyl ester; for example, they may be used in a molar ratio of 1:1.5 to 1.5:1, preferably 1:1.2 to 1.2:1, for example, 1:1. The Lewis acid can be used in conventional amounts, such as in equimolar amounts or in appropriate excess amounts compared to the reactants. More specifically, the Lewis acid is used with methyl chloroformate in a molar ratio of 2.5:1 to 1:1, preferably 2:1 to 1.3:1, and more preferably 1.5:1.

[0116] The Friedel-Crafts acylation reaction can be carried out in solvents known in the art without particular limitation. Following the Friedel-Crafts acylation reaction, the arcarbamate is hydrolyzed to obtain the arcarbamate of formula (III). This hydrolysis can be carried out in a manner known in the art, for example, hydrolysis in the presence of a base to give the corresponding salt, followed by acidification to obtain the arcarbamate.

[0117] In some embodiments of the method of the present invention, the oxime represented by formula (IV) is prepared, for example, by oximation of a ketone or aldehyde represented by formula (V) with an oximating agent selected from hydroxylamine hydrochloride, hydroxylamine, or mixtures thereof:

[0118] R1 and R2 have the same meaning as in equation (IV).

[0119] Oximation reactions are typically carried out in organic solvents, preferably in polar organic solvents. Suitable solvents include, for example, ethanol or aqueous ethanol. To promote complete oximation, salts or bases such as sodium acetate, potassium acetate, pyridine, piperidine, or triethylamine can be added. Oximation reactions can be carried out at room temperature or under heating. There are no particular limitations on the relative amounts of the ketone and the oximating agent; for example, they can be used in a molar ratio of 1:2.5 to 1:1.1, preferably 1:2 to 1:1.3, such as 1:1.5.

[0120] The aldehydes or ketones represented by formula (V) are commercially available or prepared according to known conventional methods.

[0121] The arbazoylformate oxime compound of formula (I) according to the present invention has suitable weak absorption in the near-ultraviolet to visible light radiation range, for example, 350 to 470 nm, especially in the wavelength range of 365 to 460 nm, thereby enabling effective photolysis to generate active free radicals that initiate polymerization and / or crosslinking, but without giving the cured system color. Therefore, it can be used as a photoinitiator in photocurable systems that require colorless curing and photocurable systems that require deep curing.

[0122] Unrestricted by any theory, the inventors of this invention hypothesize that the arbutin oxime ester compound represented by formula (I) undergoes photolysis under illumination by common LED light sources with emission wavelengths of 385 nm, 405 nm, and 455 nm, as shown in Figure 1. Specifically, as shown in Figure 1, under LED light irradiation, the compound first undergoes nitric oxide bond cleavage at the oxime ester structure, generating one molecule of arbutinoxy radical and one molecule of imine radical. Subsequently, the benzoyloxy radical cleaves, removing one molecule of carbon dioxide, to generate one molecule of benzoyl radical. This radical, as the dominant active radical, initiates polymerization and / or crosslinking reactions in the curing system.

[0123] Therefore, in a third aspect, the present invention provides a composition for LED photocuring, the composition comprising:

[0124] - At least one of the arbutin oxime compounds represented by formula (I) above is used as a photoinitiator, and

[0125] - A photocurable component, selected from at least one of monomers, oligomers, and prepolymers having olefinic unsaturated functional groups.

[0126] The mass ratio of the photoinitiator to the photocurable component is in the range of 0.2:100 to 6:100.

[0127] In some embodiments, the photoinitiator and the photocuring component are present in the composition for LED photocuring at a mass ratio ranging from 0.5:100 to 5:100, particularly from 1:100 to 3:100.

[0128] The present invention does not impose any particular limitation on monomers with olefinic unsaturated functions that are suitable for use as photocuring components, such as monofunctional or polyfunctional olefinic unsaturated compounds.

[0129] Examples of suitable monofunctional alkenyl unsaturated compounds include, but are not limited to: (meth)acrylic acid and its salts; (meth)acrylates, such as alkyl esters like methyl, ethyl, 2-chloroethyl, N,N-dimethylaminoethyl, n-butyl, isobutyl, pentyl, and hexyl esters; hydroxyalkyl esters like 2-hydroxyethyl, 2-hydroxypropyl, and 4-hydroxybutyl esters; and epoxyalkyl esters like glycidyl, 2,3-epoxybutyl, 3,4-epoxybutyl, 2,3-epoxycyclohexyl, and 10,11-epoxyundecyl esters. (Methacrylamide), N-substituted (meth)acrylamides, such as N-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-hexylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-cyclohexylmethacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitro... N-(4-hydroxyphenyl)acrylamide, N-ethyl-N-phenylacrylamide, N-ethyl-N-phenylmethylacrylamide, N-(4-hydroxyphenyl)acrylamide and N-(4-hydroxyphenyl)methylacrylamide; (meth)acrylonitrile; anhydrides and esters of unsaturated carboxylic acids other than (meth)acrylic acid, such as itaconic anhydride, maleic anhydride, 2,3-dimethylmaleic anhydride, 2-chloromaleic anhydride, maleic esters; styrene and substituted styrene, such as methylstyrene, chloromethylstyrene and ortho-, meta- and para-hydroxystyrene. Alkenes, divinylbenzene; vinyl ethers and halogenated vinyls, such as isobutyl vinyl ether, ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, octyl vinyl ether and phenyl vinyl ether, vinyl chloride and vinylidene chloride; vinyl and allyl esters of carboxylic acids, such as vinyl acetate, vinyl acrylate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate, divinyl succinate, diallyl phthalate, and triallyl phosphate.

[0130] Examples of suitable polyfunctional olefinic unsaturated compounds include, but are not limited to: di(meth)acrylates, such as 1,6-hexanediol diacrylate (HDDA), ethylene glycol diacrylate, propylene glycol diacrylate, glyceryl diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, glyceryl dimethacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), neopentyl glycol diacrylate, hexamethylene glycol diacrylate, bisphenol A diacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, dipentaerythritol diacrylate, etc. Dimethacrylates, tetramethylene glycol dimethacrylates, triethylene glycol dimethacrylates; tri(meth)acrylates, such as glycerol triacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, glycerol trimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol triacrylate, sorbitol triacrylate; tetra(meth)acrylates, such as pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate; penta(meth)acrylates, such as dipentaerythritol pentaacrylate, dipentaerythritol tetramethacrylate.

[0131] The present invention does not impose any particular limitation on prepolymers or oligomers with olefinic unsaturated functions suitable for use as photocuring components, such as epoxy (meth)acrylic resins, polyurethane (meth)acrylic resins, polyester (meth)acrylic resins, polyether (meth)acrylic resins, and acrylated poly (meth)acrylic resins.

[0132] The composition for LED photocuring of the present invention may optionally contain an organic solvent. The choice of organic solvent is conventional. Examples of organic solvents include aromatic hydrocarbons such as benzene and toluene, halogenated alkanes such as chloroform, dichloromethane, and chloroethane, ketones such as acetone, butanone, and pentanone, alcohols such as methanol, ethanol, propanol, isopropanol, and ethylene glycol, as well as ethylene glycol ethers, ethylene glycol ether acetates, propylene glycol ethers, and propylene glycol ether acetates.

[0133] The composition for LED curing of the present invention may optionally contain other additives, such as leveling agents, antioxidants, antisettling agents, colorants, microbial agents, such as antibacterial agents, and thermal insulation material additives.

[0134] It should be understood that the composition for LED curing of the present invention may be a mixture of the components; the composition for LED curing of the present invention may also be in the form of a component package, that is, one or more components are stored separately from one or more other components and are only formulated together to form a curing system when applied.

[0135] In a fourth aspect, the present invention provides the use of the arbutin oxime compound represented by the aforementioned formula (I) as a photoinitiator in an LED photocuring system.

[0136] In particular, the present invention provides the use of the arbamoylformate oxime compound represented by the aforementioned formula (I) in LED curing systems requiring colorless curing and LED curing systems requiring deep curing.

[0137] Specifically, the present invention includes, but is not limited to, the following technical solutions:

[0138] 1. An arbutin oxime ester compound having the structure shown in formula (I):

[0139] in,

[0140] Ar is C6-C 10 -aryl group, or C6-C group substituted with at least one group selected from the group consisting of ... 10 -Aryl: Halogen, Nitro, Hydroxyl, Thiol, Amino, C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 -Substitution of aryl groups;

[0141] R1 and R2 are independently selected from hydrogen, Q, and C1-C. 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -cycloalkyl, the aforementioned C1-C 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10-The cycloalkyl group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 The alkyl)amino group is substituted, wherein

[0142] R1 and R2 cannot be either hydrogen or Q at the same time.

[0143] Q is a coumarin group or coumarin ketone group having the structure shown in formula (II):

[0144] Among them, R3, R4, R5, R6, and R7 are independently selected from hydrogen, halogen, nitro, hydroxyl, mercapto, amino, and C1-C. 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 - Aryl group substitution,

[0145] n is 0 or 1, and

[0146] * indicates the position where group Q is connected to other structural parts.

[0147] 2. The arbutin oxime compound according to technical solution 1, wherein in formula (I), Ar is an unsubstituted or substituted phenyl or naphthyl group selected from the group consisting of: halogen, nitro, hydroxyl, mercapto, C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -Alkylthio, the aforementioned C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -The alkylthio group is optionally selected from at least one group chosen from halogen, hydroxyl, mercapto, amino, and C6-C. 10 -Substitution of aryl groups;

[0148] Preferably, Ar is an unsubstituted or substituted phenyl or naphthyl group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio groups are optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, and C6-C4. 10 -Substitution of aryl groups;

[0149] More preferably, Ar is a phenyl or a phenyl substituted with at least one, preferably one, group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally substituted with at least one group selected from halogen, hydroxyl, and mercapto.

[0150] Most preferably, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio. In particular, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio.

[0151] 3. The arbutin oxime compound according to technical solution 1 or 2, wherein in formula (I), R1 and R2 are independently selected from each other, for example, from hydrogen, Q, C1-C. 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, the aforementioned C1-C 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C6. 12 -alkoxy group, C1-C 12 -alkylthio group, mono(C1-C) 12 -alkyl)amino and di(C1-C 12 Substitution of alkyl)amino groups;

[0152] Preferably, R1 and R2 are independently selected from hydrogen, Q, C1-C8-alkyl or C1-C8-alkyl substituted with at least one group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkoxy and C1-C6-alkylthio.

[0153] More preferably, R1 is hydrogen or C1-C6-alkyl, and R2 is C1-C6-alkyl or Q; in particular, R1 is C1-C4-alkyl, such as methyl or ethyl, and R2 is C1-C4-alkyl or Q, such as methyl or ethyl;

[0154] in

[0155] R1 and R2 are not both hydrogen or group Q.

[0156] 4. The arbutin oxime compound according to any one of the aforementioned technical solutions 1-3, wherein in formula (II), R3, R5, R6 and R7 are hydrogen atoms.

[0157] R4 is selected from halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and

[0158] n is 0;

[0159] Preferably, in formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkoxy or C1-C6-alkylthio, and n is 0;

[0160] More preferably, in formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

[0161] 5. The arbutin oxime compound according to any one of the foregoing technical solutions 1-4, wherein in formula (I),

[0162] Ar is a phenyl group or a phenyl group substituted with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio.

[0163] R1 is hydrogen or C1-C6-alkyl.

[0164] R2 is a C1-C6-alkyl group or Q, wherein Q is a coumarin group having the structure shown in formula (II).

[0165] In equation (II),

[0166] R3, R5, R6, and R7 are hydrogen.

[0167] R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and

[0168] n is 0;

[0169] Preferably, in the aforementioned formula (I), Ar is a phenyl or a phenyl substituted at the para position with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio.

[0170] 6. The arbutin oxime compound according to the aforementioned technical solution 5, wherein in formula (I),

[0171] Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio.

[0172] R1 is hydrogen or a C1-C4-alkyl group.

[0173] R2 is a C1-C4-alkyl group or Q, wherein the group Q is a coumarin group having the structure shown in formula (II).

[0174] In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

[0175] 7. The arbutin oxime compound according to the aforementioned technical solution 6, wherein in formula (I),

[0176] Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of fluorine, chlorine, C1-C4-alkoxy, and C1-C4-alkylthio.

[0177] R1 is a C1-C4-alkyl group.

[0178] R2 is a C1-C4-alkyl group or Q, wherein Q is a coumarin group having the structure shown in formula (II).

[0179] In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

[0180] 8. The arbutin oxime compound according to the aforementioned technical solution 7, wherein in formula (I),

[0181] Ar is phenyl, p-fluorophenyl, p-chlorophenyl, p-methoxyphenyl, or p-ethoxyphenyl.

[0182] R1 is methyl or ethyl.

[0183] R2 is methyl, ethyl, or Q, wherein Q is a coumarin group having the structure shown in formula (II).

[0184] In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from methoxy, ethoxy, methylthio or ethylthio, and n is 0.

[0185] 9. The arbutin oxime compound according to any one of the aforementioned technical solutions 1-8, wherein neither R1 nor R2 is Q.

[0186] 10. The arbutin oxime compound according to any one of the aforementioned technical solutions 1-8, wherein R2 is Q.

[0187] 11. A method for preparing an arbutin oxime ester compound according to any one of technical claims 1-10, the method comprising esterifying an arbutinic acid of formula (III) with an oxime of formula (IV):

[0188] In Equation (III), Ar and in Equation (IV), R1 and R2 have the same meaning as Ar, R1 and R2 in Equation (I), respectively.

[0189] 12. A composition for LED photocuring, the composition comprising:

[0190] - At least one arbutin oxime compound according to any one of technical solutions 1-10 as a photoinitiator, and

[0191] - A photocurable component, selected from at least one of monomers, oligomers, and prepolymers having olefinic unsaturated functional groups.

[0192] The mass ratio of the photoinitiator to the photocurable component is in the range of 0.2:100 to 6:100, preferably in the range of 0.5:100 to 5:100, and especially in the range of 1:100 to 3:100.

[0193] 13. The composition according to claim 12, wherein the monomer is selected from at least one of the following: monofunctional olefinic unsaturated compounds, such as (meth)acrylic acid and its salts, (meth)acrylates, (meth)acrylamide, N-substituted (meth)acrylamide, (meth)acrylonitrile, anhydrides and esters of unsaturated carboxylic acids other than (meth)acrylic acid, styrene and substituted styrene, vinyl ethers and halogenated vinyls, vinyl and allyl esters of carboxylic acids; and polyfunctional olefinic unsaturated compounds, such as (meth)acrylic acid type monomers such as di(meth)acrylate, tri(meth)acrylate, tetra(meth)acrylate and penta(meth)acrylate.

[0194] 14. The composition according to claim 12, wherein the prepolymer or oligomer is selected from at least one of the following: epoxy (meth)acrylate resin, polyurethane (meth)acrylate resin, polyester (meth)acrylate resin, polyether (meth)acrylate resin, and acrylated poly (meth)acrylate resin.

[0195] 15. The use of the arylformyl oxime compound according to any one of technical solutions 1-10 as a photoinitiator in LED curing systems, particularly in LED curing systems requiring colorless curing and LED curing systems requiring deep curing.

[0196] 16. The use of the arylformyl oxime compound according to technical solution 9 in LED light curing systems requiring deep curing.

[0197] Example

[0198] The technical solution of the present invention will be further described in detail below by way of embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature or product specifications in the art.

[0199] Example 1: Synthesis of a photoinitiator AOXE with the following structure

[0200] Acetone (1.74 g, 30 mmol) and hydroxylamine hydrochloride (0.69 g, 10 mmol) were added to a 100 mL single-necked flask and reacted at room temperature for 5 h. Excess acetone was removed by vacuum distillation to obtain acetone oxime.

[0201] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), benzoylcarboxylic acid (1.50 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to another 100 mL single-necked flask, along with 30 mL of dichloromethane as a solvent. Acetone oxime (0.73 g, 10 mmol) was dissolved in 10 mL of dichloromethane and slowly added dropwise to the same flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was then dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:6 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was then distilled under reduced pressure to give the final product, AOXE.

[0202] The proton NMR data for AOXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.04–7.95 (m, 2H), 7.75–7.64 (m, 1H), 7.52 (dd, J = 8.5, 7.2Hz, 2H), 2.05 (d, J = 3.9Hz, 6H).

[0203] The carbon spectral data for AOXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 186.04, 166.27, 162.86, 135.06, 132.47, 129.87, 129.00, 21.82, 17.25.

[0204] Example 2: Synthesis of a photoinitiator F-AOXE with the following structure

[0205] 2.1 Synthesis of p-fluorobenzoylcarboxylic acid

[0206] Oxaloyl chloride monomethyl ester (1.22 g, 10 mmol) and aluminum trichloride (1.99 g, 15 mmol) were added to a 100 mL single-necked flask, along with 30 mL of dichloromethane as a solvent. Fluorobenzene (0.96 g, 10 mmol) dissolved in 30 mL of dichloromethane was slowly added dropwise to the flask using a dropping funnel, and the mixture was stirred at 5 °C until the addition was complete. After the addition was complete, the reaction was allowed to proceed for another 5 h, followed by vacuum distillation to remove the solvent and obtain methyl p-fluorobenzoylformate. 30 mL of methanol and potassium hydroxide (1.12 g, 20 mmol) were added to the obtained methyl p-fluorobenzoylformate, and the reaction was allowed to proceed for 3 h. The reaction system was then vacuum distilled to remove the solvent, and 30 mL of deionized water was added. The mixture was washed three times with 30 mL of dichloromethane. A suitable amount of dilute hydrochloric acid was added to the resulting aqueous phase to adjust the pH to approximately 3, and the mixture was extracted three times with 30 mL of dichloromethane. The combined organic phases were dried with anhydrous sodium sulfate and dichloromethane was removed by vacuum distillation to obtain p-fluorobenzoylcarboxylic acid.

[0207] 1 ¹H NMR (400 MHz, chloroform-d) δ 9.03 (s, 1H), 8.55–8.43 (m, 2H), 7.28–7.20 (m, 2H).

[0208] 13 C NMR (101MHz, chloroform-d) δ 182.45, 168.70, 166.11, 160.77, 134.65, 134.55, 128.19, 116.56.

[0209] 2.2 Synthesis of p-fluorobenzoylcarbamate acetone oxime ester

[0210] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-fluorobenzoylcarboxylic acid (1.68 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Acetone oxime (0.73 g, 10 mmol) prepared as described in Example 1 was dissolved in 10 mL of dichloromethane and slowly added dropwise to the same single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was then dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:7 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was then distilled under reduced pressure to obtain the final product, F-AOXE.

[0211] The proton NMR data for F-AOXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.10–7.98 (m, 2H), 7.21–7.12 (m, 2H), 2.03 (d, J = 6.2Hz, 6H).

[0212] The carbon spectral data for F-AOXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 184.23, 168.10, 166.49, 165.54, 162.46, 132.80, 132.70, 129.01, 116.48, 116.26, 21.74, 17.20.

[0213] Example 3: Synthesis of a photoinitiator Cl-AOXE with the following structure

[0214] 3.1 Synthesis of p-chlorobenzoylcarboxylic acid

[0215] Oxaloyl chloride monomethyl ester (1.22 g, 10 mmol) and aluminum trichloride (1.99 g, 15 mmol) were added to a 100 mL single-necked flask, along with 30 mL of dichloromethane as a solvent. Chlorobenzene (1.12 g, 10 mmol) dissolved in 30 mL of dichloromethane was slowly added dropwise to the flask using a dropping funnel, and the mixture was stirred at 5 °C until the addition was complete. After the addition was complete, the reaction was allowed to proceed for another 5 h, followed by vacuum distillation to remove the solvent and obtain methyl p-chlorobenzoylformate. 30 mL of methanol and potassium hydroxide (1.12 g, 20 mmol) were added to the obtained methyl p-chlorobenzoylformate, and the reaction was allowed to proceed for 3 h. The reaction system was then vacuum distilled to remove the solvent, and 30 mL of deionized water was added. The mixture was washed three times with 30 mL of dichloromethane. A suitable amount of dilute hydrochloric acid was added to the resulting aqueous phase to bring the pH to approximately 3, and the mixture was then extracted three times with 30 mL of dichloromethane. The combined organic phases were dried with anhydrous sodium sulfate and dichloromethane was removed by vacuum distillation to obtain p-chlorobenzoylformic acid.

[0216] 1 ¹H NMR (400 MHz, chloroform-d) δ 8.44 (s, 1H), 8.38–8.32 (m, 2H), 7.57–7.50 (m, 2H).

[0217] 13 C NMR (101 MHz, chloroform-d) δ 182.96, 160.89, 142.77, 132.79, 130.02, 129.47. 3.2 Synthesis of p-chlorobenzoylformate acetone oxime ester

[0218] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-chlorobenzoylformic acid (1.84 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Acetone oxime (0.73 g, 10 mmol) prepared as described in Example 1 was dissolved in 10 mL of dichloromethane and slowly added dropwise to the single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:7 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was distilled under reduced pressure to obtain the final product Cl-AOXE.

[0219] The proton NMR data for Cl-AOXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.05–7.91 (m, 2H), 7.63–7.40 (m, 2H), 2.08 (d, J = 5.0Hz, 6H).

[0220] The carbon spectral data for Cl-AOXE are as follows: 13C NMR (101MHz, chloroform-d) δ 184.63, 166.41, 162.32, 141.76, 131.25, 130.94, 129.43, 21.85, 17.29.

[0221] Example 4: Synthesis of a photoinitiator O-AOXE with the following structure

[0222] 4.1 Synthesis of p-methoxybenzoylcarboxylic acid

[0223] Oxaloyl chloride monomethyl ester (1.22 g, 10 mmol) and aluminum trichloride (1.99 g, 15 mmol) were added to a 100 mL single-necked flask, along with 30 mL of dichloromethane as a solvent. Anisole (1.08 g, 10 mmol) dissolved in 30 mL of dichloromethane was slowly added dropwise to the 100 mL single-necked flask using a dropping funnel, and the mixture was stirred at 5 °C until the addition was complete. After the addition was complete, the reaction was allowed to proceed for another 5 h, followed by vacuum distillation to remove the solvent and obtain methyl p-methoxybenzoylformate. 30 mL of methanol and potassium hydroxide (1.12 g, 20 mmol) were added to the obtained methyl p-methoxybenzoylformate, and the reaction was allowed to proceed for 3 h. The reaction system was then vacuum distilled to remove the solvent, and 30 mL of deionized water was added. The mixture was washed three times with 30 mL of dichloromethane. A suitable amount of dilute hydrochloric acid was added to the resulting aqueous phase to adjust the pH to approximately 3, and the mixture was then extracted three times with 30 mL of dichloromethane. The combined organic phases were dried with anhydrous sodium sulfate and dichloromethane was removed by vacuum distillation to obtain p-methoxybenzoylcarboxylic acid.

[0224] 1 ¹H NMR (400MHz, chloroform-d) δ 9.20 (s, 1H), 8.59–8.36 (m, 2H), 7.10–6.92 (m, 2H), 3.94 (s, 3H).

[0225] 13 C NMR (101MHz, chloroform-d) δ 182.73, 165.72, 162.96, 134.06, 124.75, 114.41, 55.74.

[0226] 4.2 Synthesis of p-methoxybenzoylcarbamate acetone oxime ester

[0227] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-methoxybenzoylcarboxylic acid (1.80 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Acetone oxime (0.73 g, 10 mmol) prepared as described in Example 1 was dissolved in 10 mL of dichloromethane and slowly added dropwise to the same single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:5 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was distilled under reduced pressure to obtain the final product O-AOXE.

[0228] The proton NMR data for O-AOXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.29–7.80 (m, 2H), 7.08–6.88 (m, 2H), 3.89 (s, 3H), 2.06 (d, J = 2.1Hz, 6H).

[0229] The carbon spectral data for O-AOXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 184.38, 166.24, 165.15, 162.93, 132.37, 125.42, 114.36, 55.66, 21.78, 17.19.

[0230] Example 5: Synthesis of a photoinitiator COXE with the following structure

[0231] 5.1 Synthesis of coumarin-based acetone oxime having the structure of formula IV-A

[0232] Ethyl acetoacetate (1.95 g, 15 mmol) and piperidine (0.255 g, 3 mmol) were added to a 100 mL single-necked flask, followed by 30 mL of anhydrous ethanol. 2-Hydroxy-4-methoxybenzaldehyde (1.52 g, 10 mmol) and 10 mL of anhydrous ethanol were added to a dropping funnel. The reactants from the dropping funnel were added dropwise to the single-necked flask at 25 °C. After the addition was complete, the temperature was raised to 80 °C, and the reaction was allowed to proceed for 5 h. After removing some of the solvent by rotary evaporation, recrystallization yielded 3-acetyl-7-methoxycoumarin. 3-acetyl-7-methoxycoumarin (2.18 g, 10 mmol) and hydroxylamine hydrochloride (1.05 g, 15 mmol) were added to a 100 mL single-necked flask, followed by 30 mL of ethanol. The reaction was allowed to proceed at room temperature for 5 h. Excess ethanol was removed by vacuum distillation to obtain coumarin-based acetone oxime of formula IV-A.

[0233] 1H NMR (400MHz, DMSO-d6) δ11.33(s,1H),8.02(s,1H),7.70(d,J=8.6Hz,1H),7.00(d,J=2.4Hz,1H),6.96(dd,J=8.6,2.4Hz,1H),3.86(s,3H),2.07(s,3H).

[0234] 13 C NMR (101MHz, DMSO-d6) δ163.16,159.87,155.72,152.27,141.54,130.49,121.98,113.20,112.76,100.78,56.44,13.95.

[0235] 5.2 Synthesis of Coumarin-based Benzoylcarboxylic Acid Oxime Ester

[0236] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), benzoylcarboxylic acid (1.50 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, along with 30 mL of dichloromethane as a solvent. Coumarin-based acetone oxime of formula IV-A (2.33 g, 10 mmol) was dissolved in 10 mL of dichloromethane and slowly added dropwise to the aforementioned single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:3 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was then distilled under reduced pressure to obtain the final product, COXE.

[0237] The proton NMR data for COXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.11–8.02 (m, 2H), 7.96 (s, 1H), 7.74–7.66 (m, 1H), 7.56 (t, J = 7.8 Hz, 2H), 7.43 (d, J = 8.7 Hz, 1H), 6.89 (dd, J = 8.7, 2.4 Hz, 1H), 6.82 (d, J = 2.4 Hz, 1H), 3.90 (s, 3H), 2.47 (s, 3H).

[0238] The carbon spectral data for COXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 185.64, 164.65, 164.19, 159.29, 156.53, 143.88, 135.24, 132.42, 130.70, 130.24, 129.95, 129.12, 118.76, 113.54, 111.98, 100.55, 55.96, 16.09.

[0239] Example 6: Synthesis of a photoinitiator F-COXE with the following structure

[0240] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-fluorobenzoylcarboxylic acid (1.68 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Coumarin-based acetone oxime of formula IV-A prepared as described in Example 5 (2.33 g, 10 mmol) was dissolved in 10 mL of dichloromethane and slowly added dropwise to the aforementioned single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:4 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was distilled under reduced pressure to obtain the final product F-COXE.

[0241] The proton NMR data for F-COXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.19–8.09 (m, 2H), 8.01 (s, 1H), 7.48 (d, J = 8.6 Hz, 1H), 7.25 (t, J = 8.6 Hz, 2H), 6.92 (dd, J = 8.7, 2.4 Hz, 1H), 6.85 (d, J = 2.4 Hz, 1H), 3.92 (s, 3H), 2.50 (s, 3H).

[0242] The carbon spectral data for F-COXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 183.77, 168.29, 165.72, 164.89, 164.22, 161.88, 159.23, 156.57, 143.84, 132.94, 132.85, 130.23, 128.98, 118.78, 116.64, 116.42, 113.57, 111.97, 100.57, 55.96, 16.13.

[0243] Example 7: Synthesis of a photoinitiator Cl-COXE with the following structure

[0244] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-chlorobenzoylcarboxylic acid (1.84 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Coumarin-based acetone oxime of formula IV-A prepared as described in Example 5 (2.33 g, 10 mmol) was dissolved in 10 mL of dichloromethane and slowly added dropwise to the single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:4 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was distilled under reduced pressure to obtain the final product Cl-COXE.

[0245] The proton NMR data for the photoinitiator Cl-COXE are as follows: 1 ¹H NMR (400MHz, chloroform-d) δ 8.04 (d, J = 8.3Hz, 2H), 8.00 (s, 1H), 7.56 (d, J = 8.4Hz, 2H), 7.48 (d, J = 8.6Hz, 1H), 6.92 (dd, J = 8.7, 2.3Hz, 1H), 6.86 (d, J = 2.4Hz, 1H), 3.93 (s, 3H), 2.50 (s, 3H).

[0246] Example 8: Synthesis of a photoinitiator O-COXE with the following structure

[0247] Dicyclohexylcarbodiimide (2.47 g, 12 mmol), p-methoxybenzoylcarboxylic acid (1.80 g, 10 mmol), and 4-dimethylaminopyridine (0.12 g, 1 mmol) were added to a 100 mL single-necked flask, and 30 mL of dichloromethane was added as a solvent. Coumarin-based acetone oxime of formula IV-A prepared as described in Example 5 (2.33 g, 10 mmol) was dissolved in 10 mL of dichloromethane and slowly added dropwise to the single-necked flask. The mixture was stirred at 25 °C until the addition was complete. The white precipitate was removed by filtration, and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was dissolved in dichloromethane and purified by silica gel column chromatography, using a 1:2 mixture of ethyl acetate and petroleum ether as the eluent. The eluent was distilled under reduced pressure to obtain the final product O-COXE.

[0248] The proton NMR data for O-COXE are as follows: 1¹H NMR (400MHz, chloroform-d) δ 8.09–8.04 (m, 2H), 8.03 (s, 1H), 7.47 (d, J = 8.7 Hz, 1H), 7.08–7.00 (m, 2H), 6.91 (dd, J = 8.6, 2.4 Hz, 1H), 6.84 (d, J = 2.4 Hz, 1H), 3.93 (s, 3H), 3.92 (s, 3H), 2.48 (s, 3H).

[0249] The carbon spectral data for O-COXE are as follows: 13 C NMR (101MHz, chloroform-d) δ 183.91, 165.31, 164.59, 164.14, 159.29, 156.54, 143.82, 132.56, 130.23, 125.48, 118.95, 114.47, 113.51, 112.03, 100.56, 55.95, 55.73, 16.10.

[0250] Example 9: Ultraviolet light absorption characterization

[0251] Prepare 50 mL of anhydrous acetonitrile solution of the photoinitiators (AOXE, F-AOXE, Cl-AOXE, and O-AOXE) synthesized in Examples 1 to 4, respectively, with a concentration of 1 × 10⁻⁶. -4 mol / L. The absorption curves of the four solutions in the wavelength range of 200 to 450 nm were measured using a UV spectrophotometer (Shimadzu Corporation, Japan, model UV-3600), i.e., the UV-Vis absorption spectra.

[0252] The UV-Vis absorption spectra of these four photoinitiators are shown in Figure 2. From the partial screenshots in Figure 2 within the wavelength range of 360 nm to 440 nm, it can be seen that all four photoinitiators exhibit some weak absorption around 400 nm. This weak absorption not only endows the initiators with the ability to initiate at LED emission wavelengths but also facilitates their application in curing systems requiring colorless curing and those requiring deep polymerization.

[0253] Example 10: Ultraviolet light absorption characterization

[0254] Prepare 50 mL of anhydrous acetonitrile solutions of the photoinitiators synthesized in Examples 5 to 8 (i.e., COXE, F-COXE, Cl-COXE, and O-COXE), with a concentration of 1 × 10⁻⁶. -4 mol / L. The absorption curves of the four solutions in the wavelength range of 200 to 500 nm were measured using a UV spectrophotometer (Shimadzu Corporation, Japan, model UV-3600), i.e., the UV-Vis absorption spectra.

[0255] The UV-Vis absorption spectra of these four photoinitiators are shown in Figure 3. From the partial screenshots in Figure 3 within the wavelength range of 430 nm to 470 nm, it can be seen that the maximum absorption wavelength of these four photoinitiators is around 200 nm, but they also have some weak absorption around 455 nm, which will be beneficial for their application under high-wavelength light sources.

[0256] Example 11: Photopolymerization Test

[0257] The photoinitiators synthesized in Examples 1 to 8 were applied to acrylate polymerization systems to test the performance of these photoinitiators in LED photopolymerization.

[0258] 11.1 Preparation of photosensitive solution

[0259] The photoinitiator and tripropylene glycol diacrylate monomer were mixed at a mass ratio of 1:100 and stirred evenly to prepare a photosensitive liquid.

[0260] 11.2 Performance testing of photopolymerization initiation

[0261] The prepared photosensitive solution was evenly applied onto a potassium bromide salt plate, with a coating thickness of approximately 30 μm. Then, the potassium bromide salt plate was placed over the coating. The photosensitive solution was analyzed using a real-time infrared spectrometer (Thermo Fisher Scientific, Nicolet 5700) under an LED light source (Shenzhen Lanpulike Technology Co., Ltd., UVEC-4II, 80 mW / cm²). 2 Polymerization under irradiation.

[0262] The aggregation test results are shown in Figures 4, 5, 6 and 7, respectively.

[0263] Figure 4 shows the photopolymerization kinetics of the photoinitiators AOXE, F-AOXE, Cl-AOXE and O-AOXE synthesized in Examples 1 to 4, as well as the commercially available photoinitiator OXE-01 (purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.), under a 385nm LED light source for the polymerization of tripropylene glycol diacrylate.

[0264] Figure 5 shows the photopolymerization kinetics of dipropylene glycol diacrylate polymerization initiated by the photoinitiators AOXE, F-AOXE, Cl-AOXE and O-AOXE synthesized in Examples 1 to 4, as well as the commercially available photoinitiator OXE-01, under a 405nm LED light source.

[0265] Figure 6 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate initiated by COXE, F-COXE, Cl-COXE and O-COXE synthesized in Examples 5 to 8 and the commercially available photoinitiator OXE-01 under a 405nm LED light source.

[0266] Figure 7 shows the photopolymerization kinetics of the monomer tripropylene glycol diacrylate initiated by COXE, F-COXE, Cl-COXE and O-COXE of Examples 5 to 8 and the commercially available photoinitiator OXE-01 under a 455nm LED light source.

[0267] As can be seen from Figures 4 to 7, the photoinitiator of the present invention can effectively initiate the polymerization reaction of acrylate monomers under the irradiation of LED light source, which indicates that the photoinitiator of the present invention has good initiation performance and applicability in LED photopolymerization system.

[0268] Example 12: Deep Photopolymerization Test

[0269] The photoinitiator F-AOXE synthesized in Example 2 and the commercially available OXE-01 were applied to the acrylate polymerization system to test the performance of these photoinitiators in initiating deep polymerization under LED light source irradiation.

[0270] Two photoinitiators were mixed with tripropylene glycol diacrylate monomer at a mass ratio of 1:100 and stirred evenly to prepare a photosensitive solution.

[0271] Two photosensitive solutions were injected into glass tubes with a depth of 7.5 cm and a diameter of 0.7 cm. The bottom of the tubes was illuminated with a 405 nm LED light source, with the distance between the light source and the bottom of the glass tube being 4 cm. After 60 s and 100 s of irradiation, the depth of the polymerized poly(tripropylene glycol diacrylate) in the test tubes was measured. The test results are shown in Figure 7.

[0272] Under the aforementioned conditions, the polymerization depths of the photosensitive compositions using the photoinitiator F-AXOE of the present invention were 3.2 cm and 6.65 cm after irradiation for 60 s and 100 s, respectively. In contrast, under the same conditions, the polymerization depths of the photosensitive compositions using the commercially available photoinitiator OXE-01 were only 0.5 cm and 3 cm. This indicates that the photoinitiator of the present invention has a significantly improved ability to initiate deep polymerization in LED photopolymerization systems.

[0273] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Various process solutions that are not substantially different from the concept of the present invention are all within the scope of protection of the present invention.

Claims

1. An arbutin oxime ester compound having the structure shown in formula (I): in, Ar is C6-C 10 -aryl group, or C6-C group substituted with at least one group selected from the group consisting of ... 10 -Aryl: Halogen, Nitro, Hydroxyl, Thiol, Amino, C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 -Substitution of aryl groups; R1 and R2 are independently selected from hydrogen, Q, and C1-C. 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -cycloalkyl, the aforementioned C1-C 16 -alkyl, C3-C 10 -Cycloalkyl, C3-C 10 -cycloalkyl-C1-C 16 -alkyl and C1-C 16 -alkyl-C3-C 10 -The cycloalkyl group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 The alkyl)amino group is substituted, wherein R1 and R2 cannot be either hydrogen or Q at the same time. Q is a coumarin group or coumarin ketone group having the structure shown in formula (II): Among them, R3, R4, R5, R6, and R7 are independently selected from hydrogen, halogen, nitro, hydroxyl, mercapto, amino, and C1-C. 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino, the aforementioned C1-C 16 -alkyl, C1-C 16 -alkoxy group, C1-C 16 -alkylthio group, mono(C1-C) 16 -alkyl)amino and di(C1-C 16 -alkyl)amino group is optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino and C6-C 10 - Aryl group substitution, n is 0 or 1, and * indicates the position where group Q is connected to other structural parts.

2. The arbutin oxime compound according to claim 1, wherein in formula (I), Ar is an unsubstituted or substituted phenyl or naphthyl group selected from at least one of the following groups: halogen, nitro, hydroxyl, mercapto, C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -Alkylthio, the aforementioned C1-C 12 -alkyl, C1-C 12 -alkoxy groups and C1-C 12 -The alkylthio group is optionally selected from at least one group chosen from halogen, hydroxyl, mercapto, amino, and C6-C. 10 -Substitution of aryl groups; Preferably, Ar is an unsubstituted or substituted phenyl or naphthyl group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio groups are optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, and C6-C4. 10 -Substitution of aryl groups; More preferably, Ar is a phenyl or a phenyl substituted with at least one, preferably one, group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally substituted with at least one group selected from halogen, hydroxyl, and mercapto. Most preferably, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio. In particular, Ar is a phenyl or a phenyl substituted with a group selected from the group consisting of halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio.

3. The arbutin oxime compound according to claim 1 or 2, wherein in formula (I), R1 and R2 are independently selected from each other, for example, from hydrogen, Q, C1-C. 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, the aforementioned C1-C 12 -alkyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C 12 -alkyl and C1-C 12 -alkyl-C3-C6-cycloalkyl, optionally selected from at least one group selected from halogen, nitro, hydroxyl, mercapto, amino, C1-C6. 12 -alkoxy group, C1-C 12 -alkylthio group, mono(C1-C) 12 -alkyl)amino and di(C1-C 12 Substitution of alkyl)amino groups; Preferably, R1 and R2 are independently selected from hydrogen, Q, C1-C8-alkyl or C1-C8-alkyl substituted with at least one group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkoxy and C1-C6-alkylthio. More preferably, R1 is hydrogen or C1-C6-alkyl, and R2 is C1-C6-alkyl or Q; in particular, R1 is C1-C4-alkyl, such as methyl or ethyl, and R2 is C1-C4-alkyl or Q, such as methyl or ethyl; in R1 and R2 are not both hydrogen or group Q.

4. The arbutin oxime compound according to any one of claims 1-3, wherein in formula (II), R3, R5, R6 and R7 are hydrogen atoms. R4 is selected from halogen, hydroxyl, mercapto, C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio, wherein the aforementioned C1-C8-alkyl, C1-C8-alkoxy, and C1-C8-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and n is 0; Preferably, in formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkoxy or C1-C6-alkylthio, and n is 0; More preferably, in formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

5. The arbutin oxime compound according to any one of claims 1-4, wherein in formula (I), Ar is a phenyl group or a phenyl group substituted with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio. R1 is hydrogen or C1-C6-alkyl. R2 is a C1-C6-alkyl group or Q, wherein Q is a coumarin group having the structure shown in formula (II). In equation (II), R3, R5, R6, and R7 are hydrogen. R4 is selected from halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio, wherein the aforementioned C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio are optionally selected from at least one of halogen, hydroxyl, mercapto, and C6-C6-alkyl. 10 - Aryl group substitution, and n is 0; Preferably, in the aforementioned formula (I), Ar is a phenyl or a phenyl substituted at the para position with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C6-alkyl, C1-C6-alkoxy, and C1-C6-alkylthio.

6. The arbutin oxime compound according to claim 5, wherein in formula (I), Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of: halogen, hydroxyl, mercapto, C1-C4-alkyl, C1-C4-alkoxy, and C1-C4-alkylthio. R1 is hydrogen or a C1-C4-alkyl group. R2 is a C1-C4-alkyl group or Q, wherein the group Q is a coumarin group having the structure shown in formula (II). In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from halogen, hydroxyl, mercapto, C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

7. The arbutin oxime compound according to claim 6, wherein in formula (I), Ar is a phenyl group or a phenyl group substituted at the para position with a group selected from the group consisting of fluorine, chlorine, C1-C4-alkoxy, and C1-C4-alkylthio. R1 is a C1-C4-alkyl group. R2 is a C1-C4-alkyl group or Q, wherein Q is a coumarin group having the structure shown in formula (II). In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from C1-C4-alkoxy or C1-C4-alkylthio, and n is 0.

8. The arbutin oxime compound according to claim 7, wherein in formula (I), Ar is phenyl, p-fluorophenyl, p-chlorophenyl, p-methoxyphenyl, or p-ethoxyphenyl. R1 is methyl or ethyl. R2 is methyl, ethyl, or Q, wherein Q is a coumarin group having the structure shown in formula (II). In formula (II), R3, R5, R6 and R7 are hydrogen, R4 is selected from methoxy, ethoxy, methylthio or ethylthio, and n is 0.

9. The arbutin oxime compound according to any one of claims 1-8, wherein neither R1 nor R2 is Q.

10. The arbutin oxime compound according to any one of claims 1-8, wherein R2 is Q.

11. A method for preparing an arbutin oxime ester compound according to any one of claims 1-10, the method comprising esterifying an arbutinic acid of formula (III) with an oxime of formula (IV): in, Ar in equation (III) and R1 and R2 in equation (IV) have the same meaning as Ar, R1 and R2 in equation (I).

12. A composition for LED photocuring, the composition comprising: - At least one arbutin oxime compound according to any one of claims 1-10 as a photoinitiator, and - A photocurable component, selected from at least one of monomers, oligomers, and prepolymers having olefinic unsaturated functional groups. in, The mass ratio of the photoinitiator to the photocurable component is in the range of 0.2:100 to 6:100, preferably in the range of 0.5:100 to 5:100, and especially in the range of 1:100 to 3:

100.

13. The composition of claim 12, wherein the monomer is selected from at least one of the following: monofunctional alkenyl unsaturated compounds, such as (meth)acrylic acid and its salts, (meth)acrylates, (meth)acrylamide, N-substituted (meth)acrylamide, (meth)acrylonitrile, anhydrides and esters of unsaturated carboxylic acids other than (meth)acrylic acid, styrene and substituted styrene, vinyl ethers and halogenated vinyls, vinyl and allyl esters of carboxylic acids; and polyfunctional alkenyl unsaturated compounds, such as (meth)acrylic acid type monomers such as di(meth)acrylate, tri(meth)acrylate, tetra(meth)acrylate and penta(meth)acrylate.

14. The composition of claim 12, wherein the prepolymer or oligomer is selected from at least one of the following: epoxy (meth)acrylate resin, polyurethane (meth)acrylate resin, polyester (meth)acrylate resin, polyether (meth)acrylate resin, and acrylated poly (meth)acrylate resin.

15. The use of the arbutin oxime compound according to any one of claims 1-10 as a photoinitiator in LED curing systems, particularly in LED curing systems requiring colorless curing and LED curing systems requiring deep curing.

16. Use of the arbutin oxime compound according to claim 9 in LED curing systems requiring deep curing.

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