JP7817460B2 - Oxime ester photoinitiators, their preparation and use - Google Patents

Description

This application claims priority from Chinese Patent Application No. 202210893632.X, filed July 27, 2022. This application cites the entire text of the above Chinese patent application.

This application relates to the field of organic chemistry, and specifically to oxime ester photoinitiators, their preparation methods, and their uses.

Oxime ester photoinitiators are widely used in the production of various photoresists due to their relatively excellent performance. Among these, oxime ester initiators with a carbazole base are an important type of oxime ester photoinitiator, attracting widespread attention from those skilled in the art due to their relatively high sensitivity. Highly sensitive oxime ester initiators have long been a goal pursued by industry experts, and patents CN103833872A, CN103819583A, and CN110066225A each modify the molecular structure and red-shift the absorption wavelength to improve sensitivity, resulting in initiators with high sensitivity under LED curing conditions.

However, due to yellowing issues, such initiators are difficult to apply to RGB color photoresists and transparent coating layers. Patents such as CN114369178A, CN104910053A, and Application No. 202111363587.9 have reduced the yellowing coefficient to some extent, but their photosensitivity remains unsatisfactory, and some of their structures are relatively complex, making them difficult to apply industrially. To improve the light transmittance of transparent photoresists and the color saturation of color photoresists, the photoinitiators used must have low yellowing and high photosensitivity. Therefore, it is necessary to develop new photoinitiator products with higher sensitivity and lower yellowing.

The main objective of this application is to provide an oxime ester photoinitiator, a method for producing the same, and uses thereof, in order to solve the problem that photoinitiators in the prior art are unable to achieve both high sensitivity and low yellowing.

To achieve the above objective, one aspect of the present application provides an oxime ester photoinitiator having a structure represented by general formula (I):

[In the formula, R ₁ and R ₂ are each independently selected from the group consisting of a substituted or unsubstituted C ₁ to C ₂₀ alkyl group, a substituted or unsubstituted C ₃ to C ₂₀ heteroalkyl group, a substituted or unsubstituted C ₆ to C ₂₀ aryl group, a substituted or unsubstituted C ₄ to C ₂₀ heteroaryl group, and a substituted or unsubstituted C ₃ to C ₂₀ alicyclic heterocyclic group; m is 1 or 0; n is 1 or 0; x is 1 or 0; y is 1 or 0; and z is 1 or 0.]
Furthermore, among the substituted C ₁ -C ₂₀ alkyl groups, the substituent is selected from a C ₃ -C ₁₂ heteroalkyl group; in the substituted or unsubstituted C ₁ -C ₂₀ alkyl group, at least one —CH ₂ — may be replaced by —O— or —S—;
Among the substituted C ₃ -C ₂₀ heteroalkyl groups, the substituents are selected from C ₁ -C ₁₀ linear or branched alkyl groups;
Among the substituted C ₆ to C ₂₀ aryl groups, the substituent is one or more selected from the group consisting of a C ₁ to C ₆ linear or branched alkyl group, a C ₁ to C ₁₀ linear or branched alkoxy group, a C ₁ to C ₁₀ linear or branched alkylthio group, a C ₁ to C ₈ linear or branched acyl group, a C ₁ to C ₈ linear or branched acyloxy group, a halogen atom, a cyano group, or a nitro group;
Among the substituted C ₄ -C ₂₀ heteroaryl groups, the substituents are selected from C ₁ -C ₈ linear or branched alkyl groups;
In the substituted C ₃ -C ₂₀ alicyclic heterocyclic group, the substituents are selected from C ₁ -C ₆ linear or branched alkyl groups.

Furthermore, R ₁ and R ₂ are each independently selected from a C ₁ to C ₂₀ alkyl group or a C ₆ to C ₂₀ aryl group, and preferably R ₁ and R ₂ are each independently selected from a methyl group, an ethyl group, or a phenyl group.

Furthermore, the oxime ester photoinitiator has a structure represented by any one of structural formulas (1) to (13).

Furthermore, oxime ester photoinitiators

,

or

is.

Furthermore, the manufacturing method
Carbazole

Raw material A

to form intermediate a

Step S1 to obtain
Intermediate a is mixed with raw material B

and a first Friedel-Crafts reaction to give intermediate b

Step S2 to obtain
Intermediate b is mixed with raw material C

and a second Friedel-Crafts reaction to give intermediate c

Step S3 to obtain
Intermediate c is subjected to an oximation reaction with a nitrite and/or a nitrite ester to obtain intermediate d.

Step S4 to obtain
Intermediate d is esterified with an acid anhydride and/or an acid chloride to form an oxime ester photoinitiator.

[wherein X is F, Cl, Br or I, m is 1 or 0, n is 1 or 0, x is 1 or 0, y is 1 or 0, and z is 1 or 0.]
Step S5 to obtain
Includes.

Furthermore, in step S1, the substitution reaction is carried out under alkaline conditions, the alkali being potassium hydroxide and/or sodium hydroxide; and/or in step S2, the first Friedel-Crafts reaction is carried out under aluminum chloride catalyzed conditions, the solvent for the first Friedel-Crafts reaction being dichloromethane and/or dichloroethane; and/or in step S3, the second Friedel-Crafts reaction is carried out under aluminum chloride catalyzed conditions, the solvent for the second Friedel-Crafts reaction being dichloromethane and/or dichloroethane; and/or In step S4, the nitrite salt is sodium nitrite and/or potassium nitrite, and the nitrite ester is one or more of ethyl nitrite, isopentyl nitrite, and isooctyl nitrite; preferably, the oximation reaction is carried out under acidic conditions, the acid is concentrated hydrochloric acid and/or a halogenated carboxylic acid, the halogenated carboxylic acid being chloroacetic acid or bromoacetic acid, and the solvent for the oximation reaction is one or more of ethyl acetate, tetrahydrofuran, and dichloromethane; and/or in step S5, the acid anhydride is acetic anhydride and/or benzoic anhydride, and the acid chloride is one or more of acetyl chloride, propanoic acid chloride, and benzoic acid chloride; preferably, the esterification reaction is carried out under alkaline conditions, and the alkali is one or more of triethylamine, diisopropylethylamine, and 4-dimethylaminopyridine.

Furthermore, in step S1, the molar ratio of raw material A to carbazole is (1-1.1):1, and preferably, the reaction temperature of the substitution reaction is 50-100°C, more preferably, the reaction temperature of the substitution reaction is 50-80°C; and/or in step S2, the molar ratio of raw material B to intermediate a is (1-1.1):1, and preferably, the reaction temperature of the first Friedel-Crafts reaction is -10-10°C, more preferably, the reaction temperature of the first Friedel-Crafts reaction is 0-5°C; and/or in step S3, the molar ratio of raw material C to intermediate b is (1-1.1):1, and preferably, the reaction temperature of the second Friedel-Crafts reaction is -10-10°C, more preferably, the reaction temperature of the second Friedel-Crafts reaction is 0-5°C; and/or In step S4, the molar ratio of the nitrite and/or nitrite ester to intermediate c is (2-3.5):1, and the reaction temperature of the oximation reaction is preferably 0-30°C, more preferably 20-25°C; and/or in step S5, the molar ratio of the acid anhydride and/or acid chloride to intermediate d is (2-2.8):1, and the reaction temperature of the esterification reaction is preferably 0-30°C, more preferably 20-25°C.

According to another aspect of the present application, there is provided use of the oxime ester photoinitiator of the present application in a photoresist.

According to another aspect of the present application, there is provided a photocurable composition comprising a photoinitiator, wherein the photoinitiator is the oxime ester photoinitiator of the present application. Preferably, the photocurable composition comprises, by weight, 800 to 1,000 parts of a solvent, 100 to 300 parts of an acrylate copolymer, 50 to 150 parts of dipentaerythritol hexaacrylate, and 3 to 10 parts of the oxime ester photoinitiator.

The oxime ester photoinitiator of the present application has a diketoxime ester structure, which significantly improves sensitivity. Furthermore, the provision of asymmetric substituents and the restriction of specific group types improves solubility, and its delocalized structure reduces group vibration and improves yellowing resistance. Compared to conventional photoinitiators of the same type, the oxime ester photoinitiator of the present application has significantly improved solubility and excellent usability in photocurable compositions. It not only exhibits low yellowing when used in photocurable compositions, but also has high sensitivity, thereby achieving both high sensitivity and low yellowing. Furthermore, the oxime ester photoinitiator also has advantages such as ease of synthesis and low cost, and is expected to be widely used in the photocuring field.

Note that, unless there is a contradiction, the embodiments and features of the embodiments in this application may be combined with each other. Below, the present application will be described in detail with reference to the embodiments.

Explanation of terms:
"Concentrated hydrochloric acid" is an aqueous solution of hydrochloric acid with a mass concentration of 38% or more.

As described in the background art of this application, conventional photoinitiators have the problem of being unable to achieve both high sensitivity and low yellowing. To solve this problem, one representative embodiment of this application provides an oxime ester photoinitiator having a structure represented by general formula (I):

[In the formula, R ₁ and R ₂ are each independently selected from the group consisting of a substituted or unsubstituted C ₁ to C ₂₀ alkyl group, a substituted or unsubstituted C ₃ to C ₂₀ heteroalkyl group, a substituted or unsubstituted C ₆ to C ₂₀ aryl group, a substituted or unsubstituted C ₄ to C ₂₀ heteroaryl group, and a substituted or unsubstituted C ₃ to C ₂₀ alicyclic heterocyclic group; m is 1 or 0; n is 1 or 0; x is 1 or 0; y is 1 or 0; and z is 1 or 0.]

The oxime ester photoinitiator of the present application has a diketoxime ester structure, which significantly improves sensitivity. Furthermore, the provision of asymmetric substituents and the restriction of specific group types improves solubility, and its delocalized structure reduces group vibration and improves yellowing resistance. Compared to conventional photoinitiators of the same type, the oxime ester photoinitiator of the present application has significantly improved solubility and excellent usability in photocurable compositions. It not only exhibits low yellowing when used in photocurable compositions, but also has high sensitivity, thereby achieving both high sensitivity and low yellowing. Furthermore, the oxime ester photoinitiator also has advantages such as ease of synthesis and low cost, and is expected to be widely used in the photocuring field.

Specifically, in one preferred embodiment, the substituent in the substituted C ₁ to C ₂₀ alkyl group is selected from a C ₃ to C ₁₂ heteroalkyl group; in the substituted or unsubstituted C ₁ to C ₂₀ alkyl group, at least one —CH ₂ — may be replaced by —O— or —S—;
Among the substituted C ₃ -C ₂₀ heteroalkyl groups, the substituents are selected from C ₁ -C ₁₀ linear or branched alkyl groups;
Among the substituted C ₆ to C ₂₀ aryl groups, the substituent is one or more selected from the group consisting of a C ₁ to C ₆ linear or branched alkyl group, a C ₁ to C ₁₀ linear or branched alkoxy group, a C ₁ to C ₁₀ linear or branched alkylthio group, a C ₁ to C ₈ linear or branched acyl group, a C ₁ to C ₈ linear or branched acyloxy group, a halogen atom, a cyano group, or a nitro group;
Among the substituted C ₄ -C ₂₀ heteroaryl groups, the substituents are selected from C ₁ -C ₈ linear or branched alkyl groups;
In the substituted C ₃ -C ₂₀ alicyclic heterocyclic group, the substituents are selected from C ₁ -C ₆ linear or branched alkyl groups;
The oxime ester photoinitiators having the above substituents have better dissolution performance.

In one preferred embodiment, R ₁ and R ₂ are each independently selected from a C ₁ to C ₂₀ alkyl group or a C ₆ to C ₂₀ aryl group, and preferably R ₁ and R ₂ are each independently selected from a methyl group, an ethyl group, or a phenyl group. The oxime ester photoinitiator having the above substituents has higher sensitivity and lower yellowing.

Preferably, the oxime ester photoinitiator has a structure represented by any one of structural formulas (1) to (13), and exhibits superior overall performance.

More preferably, the oxime ester photoinitiator

,

or

, most preferably an oxime ester photoinitiator
The oxime ester photoinitiator of the above structure has a greater improvement in sensitivity, better solubility, and the substituent and delocalized structure reduce the vibration of the group, which improves the yellowing resistance more effectively, and has further improved solubility, which can better achieve both high sensitivity and low yellowing, and is easier to synthesize and less expensive.

In another exemplary embodiment, the present application further provides a method for preparing the oxime ester photoinitiators of the present application, the method comprising:
Carbazole

Raw material A

to form intermediate a

Step S1 to obtain
Intermediate a is mixed with raw material B

and a first Friedel-Crafts reaction to give intermediate b

Step S2 to obtain
Intermediate b is mixed with raw material C

and a second Friedel-Crafts reaction to give intermediate c

Step S3 to obtain
Intermediate c is subjected to an oximation reaction with a nitrite and/or a nitrite ester to obtain intermediate d.

Step S4 to obtain
Intermediate d is esterified with an acid anhydride and/or an acid chloride to form an oxime ester photoinitiator.

[wherein X is F, Cl, Br or I, m is 1 or 0, n is 1 or 0, x is 1 or 0, y is 1 or 0, and z is 1 or 0.]
Step S5 to obtain
Includes.

In the present application, carbazole is first subjected to a substitution reaction with raw material A to replace the N-H of carbazole and obtain intermediate a. Intermediate a is then subjected to a first Friedel-Crafts reaction with raw material B to connect raw material B to the carbazole benzene ring and obtain intermediate b. Intermediate b is then subjected to a second Friedel-Crafts reaction with raw material C to connect raw material C to another carbazole benzene ring and obtain intermediate c. Intermediate c is then subjected to an oximation reaction with a nitrite and/or a nitrite ester to form an aldoxime structure and obtain intermediate d. Finally, intermediate d is subjected to an esterification reaction with an acid anhydride and/or an acid chloride to form an oxime ester structure and obtain the oxime ester photoinitiator of the present application.

The manufacturing method of the present application is simple, produces no contaminated waste, has high product purity, and has a high yield, making it suitable for industrial production. The oxime ester photoinitiator produced achieves both high sensitivity and low yellowing. The reaction reagents used in the process of manufacturing the above oxime ester compounds are all known in the prior art and can be commercially available or conveniently obtained by conventional synthesis methods.

Specific reaction conditions can be easily determined by one skilled in the art, given the synthetic concepts disclosed herein. In one preferred embodiment, for the purpose of improving yield, the nitrite salt is sodium nitrite and/or potassium nitrite, the nitrite ester is one or more of ethyl nitrite, isopentyl nitrite, and isooctyl nitrite, and/or the acid anhydride is acetic anhydride and/or benzoic anhydride, and the acid chloride is one or more of acetic acid chloride, propanoic acid chloride, and benzoic acid chloride.

The above reaction is carried out in an organic solvent, and the type of organic solvent is not particularly limited as long as it can dissolve the raw materials and does not adversely affect the reaction. Furthermore, in one preferred embodiment, to further improve the reaction rate, in step S1, the substitution reaction is carried out under alkaline conditions, with the alkali being potassium hydroxide and/or sodium hydroxide, and/or in step S2, the first Friedel-Crafts reaction is carried out under conditions catalyzed by aluminum chloride, with the solvent for the first Friedel-Crafts reaction being dichloromethane and/or dichloroethane, and/or in step S3, the second Friedel-Crafts reaction is carried out under conditions catalyzed by aluminum chloride, with the solvent for the first Friedel-Crafts reaction being dichloromethane and/or dichloroethane. The second Friedel-Crafts reaction is carried out under conditions catalyzed by a carboxylic acid, and the solvent for the second Friedel-Crafts reaction is dichloromethane and/or dichloroethane; and/or in step S4, the oximation reaction is carried out under acidic conditions, the acid being concentrated hydrochloric acid and/or a halogenated carboxylic acid, the halogenated carboxylic acid being chloroacetic acid or bromoacetic acid, and the solvent for the oximation reaction being one or more of ethyl acetate, tetrahydrofuran, and dichloromethane; and/or in step S5, the esterification reaction is carried out under alkaline conditions, and the alkali is one or more of triethylamine (TEA), diisopropylethylamine, and 4-dimethylaminopyridine.

In the reaction process, if the reactant added later is slightly in excess of the stoichiometric ratio in the reaction formula, a more complete reaction can be obtained. The reaction temperature varies slightly depending on the type of raw material. In one preferred embodiment, in step S1, the molar ratio of raw material A to carbazole is (1 to 1.1):1, preferably the reaction temperature of the substitution reaction is 50 to 100°C, more preferably the reaction temperature of the substitution reaction is 50 to 80°C, and/or in step S2, the molar ratio of raw material B to intermediate a is (1 to 1.1):1, preferably the reaction temperature of the first Friedel-Crafts reaction is -10 to 10°C, more preferably the reaction temperature of the first Friedel-Crafts reaction is 0 to 5°C, and/or in step S3, the molar ratio of raw material C to intermediate b is (1 to 1.1):1. ):1, preferably the reaction temperature of the second Friedel-Crafts reaction is -10 to 10°C, more preferably the reaction temperature of the second Friedel-Crafts reaction is 0 to 5°C, and/or in step S4 the molar ratio of the nitrite and/or nitrite ester to intermediate c is (2 to 3.5):1, preferably the reaction temperature of the oximation reaction is 0 to 30°C, more preferably the reaction temperature of the oximation reaction is 20 to 25°C, and/or in step S5 the molar ratio of the acid anhydride and/or acid chloride to intermediate d is (2 to 2.8):1, preferably the reaction temperature of the esterification reaction is 0 to 30°C, more preferably the reaction temperature of the esterification reaction is 20 to 25°C. When these conditions are met, optimal reaction effects can be achieved and the product yield can be increased.

In yet another exemplary embodiment of the present application, there is further provided the use of the present oxime ester photoinitiator in a photoresist. It is particularly suitable for UV-LED photocuring systems, particularly for initiation by the action of a 365 nm light source, and is characterized by excellent post-use sensitivity, low yellowing, and high solubility.

The oxime ester photoinitiator of the present application may be applied to, but is not limited to, paints, coatings, inks, molding materials, and the like. Specifically, the oxime ester photoinitiator may be used in the manufacture of: paints applied to substrates such as plastics, metals, glass, ceramics, wood, and walls; protective film materials such as hard coatings, anti-fouling films, anti-reflection films, and shock-absorbing films; photocurable pressure-sensitive adhesives, adhesives, photodegradable paints, coatings, and molded products; optical recording media such as holographic imaging materials; optical molding resins such as inks (resins) for 3D printing, photoresists for electronic circuit and semiconductor manufacturing, color filters in displays, black matrices, and photoresists for electronic materials such as dry films; interlayer insulating films, light extraction films, brightness enhancement films, and encapsulating materials; printing inks for screen printing, offset printing, gravure printing, and the like; photocurable inks for inkjet printing; optical components such as lenses, lens arrays, optical waveguides, light guide plates, light diffusers, and diffraction elements; photospacers, rib walls, nanoimprint materials, quantum dots, OLEDs, and the like.

In another exemplary embodiment, the present application further provides a photocurable composition comprising a photoinitiator, wherein the photoinitiator is the oxime ester photoinitiator of the present application, and preferably, the photocurable composition comprises, in parts by weight, 800 to 1,000 parts of a solvent, 100 to 300 parts of an acrylate copolymer, 50 to 150 parts of dipentaerythritol hexaacrylate, and 3 to 10 parts of the oxime ester photoinitiator.

The type of solvent for the composition is not particularly limited, and any solvent that can dissolve the raw materials and does not adversely affect the reaction may be used, including one or more of butanone, ethyl acetate, tetrahydrofuran, and dichloromethane. The acrylate copolymer is preferably a copolymer with a molar ratio of benzyl methacrylate: methacrylic acid: hydroxyethyl methacrylate of 70:10:20, and Mw = 10,000. The photocurable composition not only exhibits low yellowing, but also high sensitivity, achieving both high sensitivity and low yellowing. Note that the term "parts by weight" used herein has the same dimension, and both represent, for example, 1 g or 1 kg.

The present application is further described below with reference to specific examples, which should not be construed as limiting the scope of protection sought by the present application.

Example 1

(1) Preparation of Intermediate 1a

20 g of carbazole (0.12 mol), 16.70 g of cyclohexylmethyl chloride (0.13 mol), 5.76 g of sodium hydroxide (0.14 mol), and 100 mL of DMF were added to a 250 mL three-neck flask, heated to 80°C, and stirred for 4 hours. Complete reaction of the raw materials was confirmed by TLC. The reaction mixture was cooled to room temperature, filtered through diatomaceous earth, and 100 mL of dichloromethane was added to the filtrate. The mixture was then washed with water (200 mL x 3 times). The organic phase was concentrated, and the resulting residue was dissolved in n-hexane. The temperature was lowered to 5-10°C and stirred for 2 hours to crystallize. The solid was filtered, collected, and dried in an oven at 40°C to obtain 24.81 g of a white solid, i.e., Intermediate 1a, in a 78.5% yield.

(2) Preparation of Intermediate 1c

24 g of intermediate 1a (0.090 mol) and 12.60 g of aluminum chloride (0.095 mol) were dissolved in 100 mL of dichloromethane and the temperature was lowered to 0-5°C. 15.88 g of cyclohexanepropanoic acid chloride (0.091 mol) was dissolved in 20 mL of dichloromethane and added dropwise to the reaction solution. The temperature was controlled at 0-5°C to carry out the first Friedel-Crafts reaction. After the dropwise addition was completed, the mixture was stirred for 1 hour to allow the raw materials to react completely, yielding intermediate 1b.

The temperature was further lowered to 0-5°C, after which 12.60 g of aluminum chloride (0.095 mol) was added. 14.64 g of n-octanoyl chloride (0.095 mol) was added to 20 mL of dichloromethane, and the resulting mixture was added to the reaction solution. The temperature was controlled at 0-5°C to carry out a second Friedel-Crafts reaction. After the dropwise addition was completed, the mixture was stirred for 1 hour and the completion of the reaction was confirmed by TLC. The reaction mixture was gradually added to 500 mL of ice water, thoroughly stirred, and allowed to stand for 30 minutes. The organic phase was further washed with water (100 mL x 3 times), concentrated, and the resulting solid was dissolved in 200 mL of methanol. The temperature was lowered to 5-10°C, and the mixture was stirred for 2 hours to allow crystallization. The solid was then filtered and dried in an oven at 60°C to obtain 40.19 g of a white solid, i.e., Intermediate 1c, in an 84.6% yield.

(3) Preparation of Compound 1d

A 500 L round-bottom flask was charged with 45 g of intermediate 1c (0.085 mol) and 270 mL of ethyl acetate, followed by 25.5 mL of concentrated hydrochloric acid. 29.97 g of isopentyl nitrite (0.256 mol) was added dropwise at room temperature under a nitrogen gas atmosphere. After the dropwise addition was completed, the oximation reaction continued for 2 hours. 200 mL of aqueous sodium chloride was added to the reaction mixture, and the organic phase was separated. The organic phase was washed with water (200 mL x 3), concentrated, and the resulting residue was stirred with 200 mL of methanol to crystallize. The crystals were then filtered and dried in an oven at 60°C to obtain 33.91 g of a pale yellow solid, i.e., intermediate 1d, in a yield of 68.1%.

(4) Preparation of Compound 1

48 g of intermediate 1d (0.082 mol), 8.70 g of TEA (0.172 mol), and 240 mL of dichloromethane were added to a 500 mL reaction flask and stirred until the solution became clear. 8.78 g of acetic anhydride (0.172 mol) was added dropwise, and after the addition was complete, the mixture was stirred at room temperature for 2 hours to allow the esterification reaction. 200 mL of water was added to the reaction mixture, stirred for 10 minutes, and allowed to stand to separate into layers. The lower organic phase was separated and washed with water until neutral. The organic phase was concentrated, and the resulting solid was dissolved in 200 mL of methanol and stirred at reflux for 1 hour. The mixture was cooled to room temperature, stirred for 1 hour, and then placed in an ice bath to cool to 5-10°C and stirred for 1 hour. The mixture was filtered, and the filter cake was washed with 200 mL of methanol to obtain the crude product. The crude product was dissolved in 150 mL of propanone, added to 300 mL of methanol, and stirred to crystallize. The mixture was then stirred in an ice bath for 1 hour, filtered, the filter cake was rinsed with 200 mL of methanol, and the resulting solid was dried in a vacuum drying cabinet at 60°C for 24 hours to obtain 34.39 g of a pale yellow solid, i.e., Compound 1, with a yield of 62.6% and a purity of 99.12%.

The structure of compound 1 was confirmed by the following nuclear magnetic data.

1H NMR (500 MHz, Chloroform-d)δ8.61~8.57(m, 1H), 8.57~8.53(m, 1H), 7.97(dd, J=7.5, 1.5Hz, 1H), 7.92(dd, J=7.5, 1.5Hz, 1H), 7.80(d, J=7.5Hz, 1H), 7.58(d, J=7.5Hz, 1H), 4.12(d, J=7.1Hz, 2H), 2.91(d, J=7.0Hz, 2H), 2.76(t, J=7.1Hz, 2H), 2.15(s, 6H), 2.04(dq, J=13.9, 7.0Hz, 1H), 1.95(hept, J=7.0Hz, 1H), 1.65(p, J=7.1Hz, 2H), 1.59~1.50(m, 5H), 1.54~1.38(m, 16H), 1.37~1.23(m, 5H), 0.93~0.85(m, 3H).

Examples 2 to 13
According to the method of Example 1, by changing the corresponding raw materials, the following compounds 2 to 13 were prepared, the structures of which and the corresponding nuclear magnetic characterization data are shown in Table 1 below.

Examples 14 to 19
Examples 14-19 differ from Example 1 in that the molar ratios of reactants in each reaction are different, as detailed in Table 2.

Examples 20 to 25
Examples 20 to 25 differ from Example 1 in that the reaction temperatures were different, and details are shown in Table 3.

The yield and purity of Compound 1 obtained in Examples 1 and 14-25, which were obtained by changing different reaction conditions during the manufacturing process of the same compound product, are shown in Table 4.

As is clear from Tables 2 to 4, when the production molar ratios in each step of the examples are within the preferred ranges of the present application, the yield and purity of the oxime ester photoinitiator are highest. However, if the production molar ratios are too low, the reaction will be insufficient. If the ranges are exceeded, the improvement in yield and purity will be insignificant and, conversely, reagents and raw materials will be wasted, resulting in side reactions and affecting the purity of the product. When the reaction temperature in each step of the examples is within the preferred ranges of the present application, the yield and purity of the oxime ester photoinitiator are highest. However, if the temperature is too low, the reaction will be incomplete and the reaction rate will be slow. If the temperature is too high and exceeds the ranges of the present application, the improvement in yield and purity will be insignificant and, conversely, costs will increase. Therefore, it is preferable that the production molar ratios and reaction temperatures be within the preferred ranges of the present application.

Performance Evaluation : The photocurable compositions used in photosensitivity measurements in Examples 1 to 13 and Comparative Examples 1 to 4 were prepared according to the blending ratios shown in Table 5. For example, the photocurable composition of Example 1 contained, by weight, 200 parts of an acrylate copolymer, 100 parts of dipentaerythritol hexaacrylate, 5 parts of a photoinitiator, 900 parts of butanone (solvent), and 5 parts of Pigment Blue 15 (CAS: 147-14-8), and the acrylate copolymer (manufacturer: Changzhou Power Electronic New Materials Co., Ltd.) was a benzyl methacrylate/methacrylic acid/hydroxyethyl methacrylate (molar ratio of 70:10:20) copolymer with a Mw of 10,000. In the photocurable composition, the photoinitiator was the oxime ester compound represented by general formula (I) described above in the present application or a similar photoinitiator known in the prior art for comparison.

1. Solubility Measurement The solubility of an oxime ester photoinitiator in propylene glycol methyl ether acetate (PGMEA) indicates its solubility and is one of the index parameters for evaluating the application performance of the photoinitiator. Compounds having a structure represented by general formula (I) were selected, and the solubility of each of Compounds 1 to 13 and Compounds A, B, C, and D in PGMEA at 25°C was measured. The measurement results are shown in Table 6.

2. Photosensitivity Performance Measurement (1) Photosensitivity Measurement The compositions of Examples 1 to 13 and Comparative Examples 1 to 4 were stirred in the dark and coated with a 6# wire bar in a 21-step gray scale to form a coating film with a thickness of approximately 15 μm. The coating film was exposed to an LED lamp (385 nm) with 191 mJ/ ^cm² of energy (100% light intensity, 8 m/min × 2 times). After curing, the film was developed with a 2% NaOH aqueous solution for 2 minutes, and then washed with tap water for 1 minute. The gray scale measurement results were observed and are shown in Table 6.
(2) Yellowing Resistance Measurement After thoroughly stirring the photocurable compositions of Examples 1 to 13 and Comparative Examples 1 to 4 in a yellow light chamber, the compositions were applied to a tin plate with a 15# wire bar to produce a coating with a wet thickness of 10 μm. The composition was exposed to a 365 nm LED light source and received 2000 mJ/ ^cm² of energy, allowing for sufficient and complete curing. Yellowing was measured using an X-Rite color difference meter, and the yellowing resistance of the photocurable resin was determined based on the Δb value. The higher the Δb value, the more obvious the yellowing and the poorer the yellowing resistance. The yellowing resistance measurement results for Examples 1 to 13 and Comparative Examples 1 to 4 are shown in Table 6.

As a result, compared to conventional photoinitiators, the oxime ester initiators represented by formula (I) disclosed in the present application have excellent solubility in organic solvents, high sensitivity after application, and low yellowing. They are also easy to synthesize and inexpensive, and are expected to be widely used in the photocuring field.

The above is merely a preferred embodiment of the present application and is not intended to limit the present application. Those skilled in the art may find that the present application has various modifications and variations. Any amendments, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application are all included in the scope of protection of the present application.

Claims (10)

An oxime ester photoinitiator characterized by having a structure represented by general formula (I):

[In the formula, R ₁ and R ₂ are each independently selected from the group consisting of a substituted or unsubstituted C ₁ to C ₂₀ alkyl group, a substituted or unsubstituted C ₃ to C ₂₀ heteroalkyl group, a substituted or unsubstituted C ₆ to C ₂₀ aryl group, a substituted or unsubstituted C ₄ to C ₂₀ heteroaryl group, and a substituted or unsubstituted C ₃ to C ₂₀ alicyclic heterocyclic group; m is 1 or 0; n is 1 or 0; x is 1 or 0; y is 1 or 0; and z is 1 or 0.] Among the substituted C ₁ -C ₂₀ alkyl groups, the substituent is selected from a C ₃ -C ₁₂ heteroalkyl group, and in the substituted or unsubstituted C ₁ -C ₂₀ alkyl group, at least one —CH ₂ — may be replaced by —O— or —S—;
In the substituted _C3 - _C20 heteroalkyl group, the substituent is selected from a _C1 - _C10 linear or branched alkyl group;
the substituent of the substituted _C6 to _C20 aryl group is one or more selected from the group consisting of a _C1 to _C6 linear or branched alkyl group, a _C1 to _C10 linear or branched alkoxy group, a _C1 to _C10 linear or branched alkylthio group, a _C1 to _C8 linear or branched acyl group, a _C1 to _C8 linear or branched acyloxy group, a halogen atom, a cyano group, or a nitro group;
In the substituted C ₄ -C ₂₀ heteroaryl group, the substituent is selected from C ₁ -C ₈ linear or branched alkyl groups;
The oxime ester photoinitiator according to claim 1, characterized in that the substituent of the substituted _C3 - _C20 alicyclic heterocyclic group is selected from _C1 - _C6 linear or branched alkyl groups. The oxime ester photoinitiator according to claim 1, characterized in that R ₁ and R ₂ are each independently selected from a C ₁ to C ₂₀ alkyl group or a C ₆ to C ₂₀ aryl group, preferably R ₁ and R ₂ are each independently selected from a methyl group, an ethyl group or a phenyl group. The oxime ester photoinitiator according to claim 1 , wherein the oxime ester photoinitiator has a structure represented by any one of structural formulas (1) to (13).












the oxime ester photoinitiator

,

or

2. The oxime ester photoinitiator of claim 1 , wherein Carbazole

Raw material A

to form intermediate a

Step S1 to obtain
The intermediate a is converted into raw material B

and a first Friedel-Crafts reaction to give intermediate b

Step S2 to obtain
The intermediate b is converted into raw material C

and a second Friedel-Crafts reaction to give intermediate c

Step S3 to obtain
The intermediate c is subjected to an oximation reaction with a nitrite and/or a nitrite ester to obtain an intermediate d

Step S4 to obtain
The intermediate d is subjected to an esterification reaction with an acid anhydride and/or an acid chloride, and the oxime ester photoinitiator

[wherein X is F, Cl, Br or I, m is 1 or 0, n is 1 or 0, x is 1 or 0, y is 1 or 0, and z is 1 or 0.]
Step S5 to obtain
A method for producing the oxime ester photoinitiator according to any one of claims 1 to 5, comprising: In step S1, the substitution reaction is carried out under alkaline conditions, and the alkali is potassium hydroxide and/or sodium hydroxide; and/or in step S2, the first Friedel-Crafts reaction is carried out under aluminum chloride catalyzed conditions, and the solvent for the first Friedel-Crafts reaction is dichloromethane and/or dichloroethane; and/or in step S3, the second Friedel-Crafts reaction is carried out under aluminum chloride catalyzed conditions, and the solvent for the second Friedel-Crafts reaction is dichloromethane and/or dichloroethane; and/or The method according to claim 6, wherein in step S4, the nitrite salt is sodium nitrite and/or potassium nitrite, and the nitrite ester is one or more of ethyl nitrite, isopentyl nitrite, and isooctyl nitrite; preferably, the oximation reaction is carried out under acidic conditions, the acid being concentrated hydrochloric acid and/or a halogenated carboxylic acid, the halogenated carboxylic acid being chloroacetic acid or bromoacetic acid, and the solvent for the oximation reaction being one or more of ethyl acetate, tetrahydrofuran, and dichloromethane; and/or, in step S5, the acid anhydride is acetic anhydride and/or benzoic anhydride, and the acid chloride is one or more of acetyl chloride, propanoic acid chloride, and benzoic acid chloride; preferably, the esterification reaction is carried out under alkaline conditions, the alkali being one or more of triethylamine, diisopropylethylamine, and 4-dimethylaminopyridine. In the step S1, the molar ratio of the raw material A to the carbazole is (1 to 1.1):1, and preferably, the reaction temperature of the substitution reaction is 50 to 100°C, more preferably, the reaction temperature of the substitution reaction is 50 to 80°C; and/or In the step S2, the molar ratio of the raw material B to the intermediate a is (1 to 1.1):1, and preferably, the reaction temperature of the first Friedel-Crafts reaction is -10 to 10°C, more preferably, the reaction temperature of the first Friedel-Crafts reaction is 0 to 5°C; and/or In the step S3, the molar ratio of the raw material C to the intermediate b is (1 to 1.1):1, and preferably, the reaction temperature of the second Friedel-Crafts reaction is -10 to 10°C, more preferably, the reaction temperature of the second Friedel-Crafts reaction is 0 to 5°C; and/or The method according to claim 6, wherein in step S4, the molar ratio of the nitrite and/or nitrite ester to the intermediate c is (2 to 3.5):1, and the reaction temperature of the oximation reaction is preferably 0 to 30°C, more preferably 20 to 25°C; and/or in step S5, the molar ratio of the acid anhydride and/or acid chloride to the intermediate d is (2 to 2.8): 1 , and the reaction temperature of the esterification reaction is preferably 0 to 30°C, more preferably 20 to 25°C. Use of the oxime ester photoinitiator described in any one of claims 1 to 5 in a photoresist. 1. A photocurable composition comprising a photoinitiator,
6. A photocurable composition, wherein the photoinitiator is the oxime ester photoinitiator of any one of claims 1 to 5, preferably comprising, in parts by weight, 800 to 1000 parts of a solvent, 100 to 300 parts of an acrylate copolymer, 50 to 150 parts of dipentaerythritol hexaacrylate, and 3 to 10 parts of the oxime ester photoinitiator.