(2, 4, 6-trimethylbenzoyl) (3, 4-dimethylphenyl) phenylphosphine oxide photoinitiator as well as preparation method and application thereof

Abstract

The invention relates to a (2, 4, 6-trimethylbenzoyl) (3, 4-xylene) phenyl phosphine oxide photoinitiator and a preparation method and application thereof, and the preparation method comprises the following steps: preparing (3, 4-xylene) phenyl phosphine chloride, preparing (3, 4-xylene) phenyl phosphine oxide, and preparing (2, 4, 6-trimethylbenzoyl) (3, 4-xylene) phenyl phosphine oxide. Compared with the prior art, the preparation method disclosed by the invention is a brand new photoinitiator compound, the product purity is up to 99%, the wastewater generation amount in the production process is greatly reduced, the performance test of the substance is superior to the product performance of the same series of acylphosphine oxide photoinitiators, and the raw materials required by the process are all bulk chemical raw materials, are stable in source, and are suitable for industrial production. The maximum absorption strength of XTPO is superior to that of the main product TPO at present, the curing efficiency of the initiator is higher, and the coloring stability is better.

Description

Technical Field

[0001] The invention relates to the technical field of new materials for light radiation free radical polymerization, and in particular to a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator, a preparation method and application thereof. Background Art

[0002] The light absorption properties and reaction activity of the photoinitiator determine the performance of the entire photoreaction system. It is widely used in light-emitting diode (LED) curing, ink photocuring, 3D printing, medical dentistry and other fields. There are many types of photoinitiators. According to their initiation mechanism, they can be divided into cationic photoinitiators and free radical photoinitiators. Cationic photoinitiators mainly excite molecules by light, causing the molecules to decompose and generate super strong proton acids to initiate polymerization, including sulfonium salts, iodonium salts and aromatic hydrocarbons. Free radical photoinitiators include hydrogen abstraction type and cleavage type. The main principle of hydrogen abstraction type photoinitiators is to generate free radicals through light initiation, extract hydrogen atoms in the auxiliary agent to transfer charge, and thus initiate monomer polymerization. The main types are thioxanthone and benzophenone. Cleavage type photoinitiators mainly produce primary active species that initiate prepolymer self-crosslinking through homolysis, including acylphosphine oxides (APOs), benzil derivatives, etc. Currently, the commercialized acylphosphine oxide photoinitiators mainly include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 2,4, 6-trimethylbenzoylphosphonic acid ethyl ester (TPO-L), and bis(2,4, 6-trimethylbenzoyl)phenylphosphine oxide (Irgacure819, photoinitiator 819). Compared with traditional cationic photoinitiators, the absorption wavelength of acylphosphine oxide photoinitiators moves to the visible light region and can extend to 420 nm. During the curing process, the P-C bond between the phosphonyl group and the aromatic acyl group is easily broken by light, generating carbonyl radicals and phosphonyl radicals, which initiate the polymerization reaction of the monomer. The chromophores are mainly carbonyl and phosphonyl groups. The breaking of the P-C bond allows the incident light to pass through the surface layer into the deeper layer, achieving deep curing. Ultraviolet LED (UVLED) can be used to replace the traditional mercury lamp. Acylphosphine oxide photoinitiators absorb light energy and gradually decompose, with fast speed, high efficiency, and obvious photobleaching effect. Due to their unique chemical structure, acylphosphine oxide-type photoinitiators have excellent comprehensive properties and are widely used in paints, 3D printing, dental restoration and other fields.

[0003] The most commonly used acylphosphine oxide photoinitiators in the market are mainly TPO, TPO-L, and 819. Since TPO has reproductive toxicity and has been listed in the EU SVHC list, TPO-L has a long curing reaction time, and 819 has many problems such as yellowing, a large amount of wastewater will be generated in the process of preparing TPO by the acyl chloride method and the aldehyde method. Therefore, it is imperative to develop a new material synthesis process with mild reaction conditions, green environmental protection and health. Summary of the invention

[0004] The purpose of the present invention is to provide a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenyl phosphine oxide photoinitiator and a preparation method and application thereof in order to solve the above problems. The preparation method of the present invention mainly uses phenyl phosphorus dichloride and as raw materials to react under the catalysis of catalyst A to generate (3,4-xylyl) phenyl phosphine chloride and o-xylene as raw materials to prepare (3,4-xylyl) phenyl phosphine chloride, further prepare (3,4-xylyl) phenyl phosphine oxide, and further prepare (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenyl phosphine oxide. A new photoinitiator compound can be synthesized, the product has high purity, the maximum absorption intensity is better than the current main product TPO, and the performance test is better than the product performance of the same series of acylphosphine oxide photoinitiators.

[0005] The purpose of the present invention is achieved through the following technical solutions: The first object of the present invention is to provide a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide (XTPO) photoinitiator. The present invention relates to the technical field of new materials for photoradiation free radical polymerization, and in particular to a synthesis scheme of a new commercial photoinitiator compound (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide. The preparation method comprises the following steps: Preparation of (3,4-dimethylphenyl)phenylphosphine chloride; Preparation of (3,4-dimethylphenyl)phenylphosphine oxide; Preparation of (2,4,6-trimethylbenzoyl)(3,4-dimethylphenyl)phenylphosphine oxide.

[0006] Furthermore, the preparation method comprises the following steps: (1) Using phenylphosphonium dichloride and o-xylene as raw materials, under the catalysis of catalyst A, (3,4-xylyl)phenylphosphonium chloride is reacted; (2) adding the (3,4-xylyl)phenylphosphine chloride obtained in step (1) to a mixed solution of water and dichloroethane to react and generate (3,4-xylyl)phenylphosphine oxide; (3) The (3,4-xylyl)phenylphosphine oxide obtained in step (2) is reacted with 2,4,6-trimethylbenzoyl chloride to obtain the (2,4,6-trimethylbenzoyl) (3,4-xylyl)phenylphosphine oxide.

[0007] Furthermore, in step (1), catalyst A is at least one of aluminum chloride, gallium chloride, indium chloride, bismuth chloride, antimony chloride, tin chloride, magnesium chloride and ferric chloride.

[0008] Further, in step (1), the reaction temperature is 20°C-120°C; Furthermore, in step (1), the reaction time is 2-18 hours.

[0009] Furthermore, step (1) specifically includes the following process: Add o-xylene and aluminum chloride under nitrogen environment, then add phenylphosphonium dichloride dropwise at 20-90°C under nitrogen environment (addition takes about 1.5 hours), keep warm at 30°C for 10 hours, stop the reaction, and cool down to obtain (3,4-xylyl)phenylphosphonium chloride.

[0010] Furthermore, step (2) specifically includes the following process: The (3,4-xylyl)phenylphosphine chloride obtained in step (1) is poured into a mixed solution of water and dichloroethane at a temperature below 90° C., stirred for 10 minutes, separated, and the organic layer is added with sodium carbonate aqueous solution to adjust the pH to 2 and stirred for 10 minutes. The organic layer is separated, and toluene is added to the organic layer for reflux dehydration to obtain (3,4-xylyl)phenylphosphine oxide.

[0011] Furthermore, step (3) specifically includes the following process: Add triethylamine to (3,4-xylyl)phenylphosphine oxide, add trimethylsilyl chloride at 5-15°C with stirring, keep warm at 50°C for 12h after the addition, add 2,4,6-trimethylbenzoyl chloride at 50°C, keep warm for 2h after the addition, evaporate trimethylsilyl chloride to obtain a residual liquid, add water with a weight of 1 times the residual liquid to the residual liquid, wash with water twice, cool the organic layer and crystallize to obtain a crude product of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide.

[0012] Furthermore, the crude (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide was added with ethanol in an amount 1 times the weight of the crude product, the temperature was raised to 5-15° C., stirred to completely dissolve, and then cooled to crystallize to obtain the product (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide.

[0013] Furthermore, in step (3), trimethylsilyl chloride is added dropwise; in step (3), 2,4,6-trimethylbenzoyl chloride is added dropwise.

[0014] Furthermore, the dropping rate was about 1.5 hours to add 100 g.

[0015] Furthermore, the purity of the (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide photoinitiator is greater than 99%.

[0016] The second object of the present invention is to provide a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator prepared by the above preparation method.

[0017] Furthermore, the structural formula of the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide is as follows: .

[0018] Furthermore, the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator product has good purity, high yield, good appearance, and performance tests are better than those of the same series of photoinitiator products.

[0019] Furthermore, the maximum absorption peak λ of the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide max At around 380 nm, the maximum absorption intensity of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide is greater than the maximum absorption intensity of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and the absorption coefficient of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide is greater than the absorption coefficient of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, indicating a stronger initiation effect.

[0020] The third object of the present invention is to provide an application of a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator, wherein the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator is an acylphosphine oxide type photoinitiator, and the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator is used in ink or coating processes.

[0021] Furthermore, the (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide can be used as a photoinitiator, and is a core auxiliary agent for initiating the successful polymerization of UV light-curing materials after exposure. With the help of energy irradiation (ultraviolet light UV), the chemical formula is converted from liquid to solid, and a high-strength protective film is formed. It is mainly used in new environmentally friendly ink and coating processes.

[0022] The technical concept of this application includes the following contents: The present application uses the trimethylchlorosilane method to prepare XTPO, which has lower costs during the reaction process, and the intermediate products are easier to obtain, and trimethylchlorosilane can be recycled and reused.

[0023] If XTPO is produced by the aldehyde method, the cost is very high, there are many reaction steps, the reaction conditions are very harsh, the amount of wastewater is large, and the yield is also very low (generally only 80%).

[0024] 3. The inventive substance of this application is a new substance.

[0025] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects: 1) This scheme provides a synthesis scheme for a photoinitiator, which is a new compound (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide. (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide can be used as a photoinitiator and is a core auxiliary agent for initiating the successful polymerization of UV light-curing materials after exposure. With the help of energy irradiation (ultraviolet light UV), the chemical formula is converted from liquid to solid, and a high-strength protective film is formed. It is mainly used in new environmentally friendly ink and coating processes.

[0026] 2) This scheme provides a new synthesis of photoinitiator, and the material is more environmentally friendly. The (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide produced by the process of the present invention has good purity, high yield, good appearance, and performance test is better than the same series of photoinitiator products.

[0027] 3) This scheme provides a new synthesis preparation of photoinitiator compounds with a product purity of up to 99%. The amount of wastewater generated during the production process is greatly reduced. The performance test of this substance is better than the product performance of the same series of acylphosphine oxide photoinitiators. The raw materials required for the process are all bulk chemical raw materials with stable sources. The maximum absorption intensity of XTPO is better than that of the current main product TPO. The initiator has higher curing efficiency and better coloring stability.

[0028] 4) The XTPO prepared by the trichlorosilane method in this application does not produce ethyl chloride as a byproduct, and trichlorosilane can be reused, and the amount of wastewater produced is also less than that produced by the aldehyde method. If the XTPO is prepared by the aldehyde method (including impurities such as (2,4-xylyl)phenylphosphine chloride and (2,5-xylyl)phenylphosphine chloride), there will be defects such as low yield, high cost, and large amount of wastewater. The XTPO ((3,4-xylyl)phenylphosphine chloride) prepared by the trichlorosilane method in this application has low manufacturing cost, high initiation efficiency, and excellent anti-yellowing effect, and is a good candidate product for TPO substitutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The UV spectra of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide (XTPO) prepared in Example 1 of the present invention are compared with those of commercially available TPO.

[0030] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments, but is by no means intended to limit the present invention. Features such as preparation methods, materials, structures or composition ratios not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0032] The purpose of the present invention is to provide a new synthesis of a photoinitiator, and the material is relatively environmentally friendly. The process mainly uses phenylphosphonic acid dichloride as a raw material and reacts under the catalysis of catalyst A to generate (3,4-xylyl)phenylphosphonic acid chloride. The reaction formula is as follows:

[0033] Catalyst A is at least one of aluminum chloride, gallium chloride, indium chloride, bismuth chloride, antimony chloride, tin chloride, magnesium chloride, and ferric chloride. The reaction temperature is 20°C-90°C, the reaction time is 2-18 hours, and the yield can reach 90-96%. The synthesis reaction of (3,4-dimethylphenyl)phenylphosphine oxide is as follows:

[0034] The synthesis method of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide is as follows:

[0035] It can be synthesized from 2,4,6-trimethylbenzoyl chloride and (3,4-xylyl)phenylphosphine oxide.

[0036] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0037] In the following examples, TPO is commercially available TPO. The CAS number of phenylphosphonium dichloride is 644-97-3, and the CAS number of 2,4,6-trimethylbenzoyl chloride is 938-18-1.

[0038] Example 1

[0039] This embodiment provides a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator, which is completed by the following three steps.

[0040] (1) Preparation of (3,4-xylyl)phenylphosphine chloride: 88.8 g of o-xylene and 140 g of aluminum trichloride (i.e., aluminum chloride) were added under N2 environment, the temperature was raised from 20°C to 90°C under N2, and 100 g of phenylphosphine dichloride was added dropwise (addition was completed in about 1.5 hours), and the temperature was kept at 30°C for 10 hours after the addition was completed. The reaction was stopped and the temperature was lowered to obtain (3,4-xylyl)phenylphosphine chloride. The yield was 97% and the purity was 98%.

[0041] (2) Preparation of (3,4-xylyl)phenylphosphine oxide: Pour the (3,4-xylyl)phenylphosphine chloride obtained in step (1) into a solution containing 100 g of water and 300 g of dichloroethane at a temperature below 90°C and stir while pouring. Stir for 10 minutes after pouring to separate the liquids. Add 100 g of dichloroethane to the aqueous layer for extraction (if there is residual mother liquor, add dichloroethane for more thorough extraction). Add sodium carbonate aqueous solution to the organic layer to adjust the pH to 2 and stir for 10 minutes. Separate the liquids again. Add 100 g of toluene to the organic layer and reflux for dehydration to obtain (3,4-xylyl)phenylphosphine oxide (yield of about 95%).

[0042] (3) Preparation of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide: 94.2 g of triethylamine was added to (3,4-xylyl)phenylphosphine oxide under N2 protection, 69 g of trimethylsilyl chloride was added dropwise at 10°C with stirring, and the temperature was kept at 50°C for 12 h after the addition was completed. 27 g of 2,4,6-trimethylbenzoyl chloride was added dropwise at this temperature, and the temperature was kept at 50°C for 2 h after the addition was completed. After the trimethylsilyl chloride was evaporated, methanol was added dropwise to the residual liquid according to the amount of residual 2,4,6-trimethylbenzoyl chloride (determined by HPLC). In this embodiment, 100g methanol is added dropwise, and the excess methanol reacts with the remaining 2,4,6-trimethylbenzoyl chloride. No gas is generated during the reaction process. The excess methanol will be washed away with water. Water with a weight of 1 times the residual liquid is added, and the water is washed twice. The organic layer is cooled and crystallized to obtain a crude XTPO product (yield of about 90%). The crude product is added with ethanol with a weight of 1 times the crude product, and the temperature is raised to 10°C and stirred until the crude product is completely dissolved. Then the temperature is cooled and crystallized (the cooling crystallization is to cool to 0°C) to obtain the product (yield of about 95%) (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide, with a purity of 99.3%. Figure 2 Shown is the hydrogen nuclear magnetic resonance spectrum of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide prepared in Example 1 of the present invention.

[0043] like Figure 1 As shown, the maximum absorption wavelength λ of the maximum absorption peak of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide (XTPO) prepared in this example maxAt around 380 nm, compared with (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, the maximum absorption wavelength has not changed much, but the maximum absorption intensity of (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide is greater than that of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, and the absorption coefficient of (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide is greater than that of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, which has a stronger initiation effect.

[0044] Example 2

[0045] The present embodiment provides a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator. The difference between the present embodiment and the embodiment 1 is that in the present embodiment, the dropping in step (1) is completed and the temperature is kept at 30° C. for 2 h. The other conditions are the same as those in the embodiment 1. The product (yield of about 93%) (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide is obtained in the present embodiment with a purity of 99.0%.

[0046] Example 3

[0047] This embodiment provides a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator. The difference between this embodiment and embodiment 1 is that in this embodiment, 69 g of trimethylsilyl chloride is added dropwise at 15° C. under stirring in step (3). Other conditions are the same as those in embodiment 1. This embodiment obtains a product (yield of about 94%) (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide with a purity of 99.2%.

[0048] Example 4

[0049] The present embodiment provides a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator. The difference between the present embodiment and the embodiment 1 is that in the present embodiment, the organic layer in step (3) is cooled and crystallized to obtain a crude XTPO product (yield of about 90%), and the crude product is added with ethanol in an amount of one time the weight of the crude product, and the temperature is raised to 15° C. and stirred to completely dissolve the crude product, and then cooled and crystallized (the cooling and crystallization is cooling to 0° C.) to obtain a product (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide. The other conditions are the same as those in the embodiment 1. The product (yield of about 96%) (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide obtained in the present embodiment has a purity of 99.4%.

[0050] Example 5

[0051] This embodiment provides a method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator. The difference between this embodiment and embodiment 1 is that in this embodiment, in step (2), the aqueous layer is not extracted with 100 g of dichloroethane. Other conditions are the same as those in embodiment 1. In this embodiment, the product (yield of about 92%) (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide is obtained with a purity of 98.5%.

[0052] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator, characterized in that: The preparation method comprises the following steps: (1) Using phenylphosphonium dichloride and o-xylene as raw materials, under the catalysis of catalyst A, (3,4-xylyl)phenylphosphonium chloride is reacted; (2) adding the (3,4-xylyl)phenylphosphine chloride obtained in step (1) to a mixed solution of water and dichloroethane to react and generate (3,4-xylyl)phenylphosphine oxide; (3) reacting the (3,4-xylyl)phenylphosphine oxide obtained in step (2) with 2,4,6-trimethylbenzoyl chloride to obtain a (2,4,6-trimethylbenzoyl) (3,4-xylyl)phenylphosphine oxide photoinitiator; In step (1), the catalyst A is at least one of aluminum chloride, gallium chloride, indium chloride, bismuth chloride, antimony chloride, tin chloride, magnesium chloride and ferric chloride.

2. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 1, characterized in that: In step (1), the reaction temperature is 20°C-90°C, and the reaction time is 2-18 hours.

3. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 1, characterized in that: Step (2) specifically includes the following process: The (3,4-xylyl)phenylphosphine chloride obtained in step (1) is poured into a mixed solution of water and dichloroethane at a temperature below 90° C., stirred for 10 minutes, separated, and the organic layer is added with sodium carbonate aqueous solution to adjust the pH to 2, stirred for 10 minutes, separated, and the organic layer is added with toluene for reflux dehydration to obtain (3,4-xylyl)phenylphosphine oxide.

4. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 3, characterized in that: Step (3) specifically includes the following process: Add triethylamine to (3,4-xylyl)phenylphosphine oxide, add trimethylsilyl chloride at 5-15°C with stirring, keep warm at 50°C for 12h after the addition, add 2,4,6-trimethylbenzoyl chloride at 50°C, keep warm for 2h after the addition, evaporate trimethylsilyl chloride to obtain a residual liquid, add water with a weight of 1 times the residual liquid to the residual liquid, wash with water twice, cool the organic layer and crystallize to obtain a crude product of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide.

5. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 4, characterized in that: Add ethanol in an amount 1 times the weight of the crude product of (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide to the crude product, raise the temperature to 5-15° C., stir to completely dissolve, then cool and crystallize to obtain the product (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide.

6. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 4, characterized in that: In step (3), trimethylsilyl chloride is added dropwise, and 2,4,6-trimethylbenzoyl chloride is added dropwise.

7. The method for preparing a (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator according to claim 1, characterized in that: The purity of the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator is greater than 99%.

8. A (2,4,6-trimethylbenzoyl)(3,4-xylyl)phenylphosphine oxide photoinitiator prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator as claimed in claim 8, characterized in that: The (2,4,6-trimethylbenzoyl) (3,4-xylyl) phenylphosphine oxide photoinitiator is used in ink or coating technology.

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