2, 4, 6-trimethylbenzoyl phosphine oxide derivative as well as preparation method and application thereof

Abstract

The invention relates to a 2, 4, 6-trimethylbenzoyl phosphine oxide derivative and a preparation method and application thereof, the derivative has the following structural formula: R1 = CnH2n + 1 (n = 1-4), R2 = phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, OCnH2n + 1 (n = 1-4), R3 = phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2, 4, 6-trimethyl-3, 5-bis (diethoxy phosphoryl methyl) benzoyl (when R2 = phenyl). The preparation method comprises the following steps: mixing halomethylated 2, 4, 6-trimethylbenzoyl phosphine oxide with phosphite esters, and carrying out an Arbuzov rearrangement reaction to obtain the 2, 4, 6-trimethylbenzoyl phosphine oxide derivative which is used as a photoinitiator. Compared with the prior art, the photoinitiator with higher electron cloud density is obtained, and although the molecular weight is almost doubled, the initiation efficiency is increased instead of being reduced; the structure of a product after photolysis is not beneficial to generation of colored groups, yellowing is reduced, and meanwhile, in formula application, due to the fact that the molecular weight is improved, taste and migration are reduced.

Description

Technical Field

[0001] This invention relates to the photocuring industry in the field of organic chemistry, specifically to acylphosphine oxide photoinitiators and their synthesis methods, and particularly to a 2,4,6-trimethylbenzoylphosphine oxide derivative, its preparation method, and its application. Background Technology

[0002] As is well known, photoinitiators are crucial components in the field of photocuring, and currently, they are almost indispensable, playing a decisive role in the curing speed of photocurable coatings, inks, and adhesives. A photoinitiator is a substance that absorbs radiation energy, undergoes a chemical change upon excitation, and produces an active intermediate (free radical or cation) with polymerization initiation capabilities, further initiating the curing of a polymer system containing active functional groups into a film. Among the many types of photoinitiators, acylphosphine oxide photoinitiators, due to their unique optical characteristics, are the most widely used type in the photocuring industry, occupying a pivotal position in the field of photoinitiators. Among them, 2,4,6-trimethylbenzoylphosphine oxide photoinitiators such as TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), 819 (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide), TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphonate), and TMO (2,4,6-trimethylbenzoyl-di-p-tolylphosphine oxide) are widely used in UV-cured coatings, inks, adhesives, and other industries. However, existing acylphosphine oxide photoinitiators have some shortcomings: TPO has good overall performance and a moderate price, making it the most popular type of acylphosphine oxide photoinitiator. However, due to reproductive toxicity issues, the EU has issued a ban on it, which has now also affected Chinese export companies.

[0003] The initiation activity of TPO-L is insufficient, which affects its application.

[0004] 819 and TMO have better initiation activity than TPO and no toxicity issues, but they are more expensive and have poor resistance to yellowing. They also have odor issues before and after photocuring, which affects their application.

[0005] Patent application CN202111641085.8 discloses a method for preparing a modified acyl phosphine oxide photoinitiator and its application in photocurable materials. This technology introduces an acyl group into the trimethylbenzoyl group of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO). On the one hand, this increases the molecular weight of this part, making the photolysis product odorless, non-migrating, non-volatile, or with a small volatile odor. On the other hand, it causes a red shift in the ultraviolet absorption spectrum of the entire photoinitiator, expanding the width of its photolysis spectrum. However, this technology still has the following problems: 1) In this synthetic route, except for α-haloacyl chloride, the Friedel-Crafts acylation reactions are relatively slow, some even taking up to a month to complete; 2) The final products obtained, except for α-haloacylated TPO, have poor solubility in commonly used reactive diluents; 3) The α-haloacylated TPO contains halogens in its molecule, which limits its application range, especially its inability to be used in electronic products; 4) α-haloacylated TPO yellows significantly and cannot be used in white or light-colored systems.

[0006] Patent application CN202310509140.0 discloses a series of TPO {diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride} photoinitiator derivatives. By introducing chloromethyl or acyl groups at the 3rd or (and) 5th positions of the benzene ring of the trimethylbenzoyl group, a reactive intermediate is obtained. Further introduction of ester groups or other structures yields a series of photoinitiators with higher electron cloud density, resulting in a redshift of the ultraviolet absorption wave or more and stronger ultraviolet absorption peaks, thus improving initiation efficiency. Simultaneously, it increases the molecular weight of the photolysis products, reducing taste and migration issues in formulation applications. However, this technology still has the following problems: 1) The TPO derivatives obtained by this technical route have poor solubility in commonly used reactive diluents; 2) The synthesis of these TPO derivatives must be completed in aprotic polar solvents (such as DMF, DMSO, etc.), which makes post-processing relatively complicated and increases production costs. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a 2,4,6-trimethylbenzoylphosphine oxide derivative. Based on CN202111641085.8 and CN202310509140.0, the inventors further studied the use of TPO, 819, TPO-L, TMO or similar substances as substrates to introduce new structures or groups for modification, increase the molecular weight of the pyrolysis products, make the photolysis products tasteless, not volatile or have a small volatile odor that is acceptable to the senses, and at the same time improve their initiation efficiency and reduce their migration rate.

[0008] The objective of this invention can be achieved through the following technical solution: a 2,4,6-trimethylbenzoylphosphine oxide derivative having the following structural formula:

[0009] Where R1=C n H 2n+1 (n=1~4), R2=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or OC n H 2n+1 (n=1~4), R3=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or 2,4,6trimethyl-3,5-bis(diethoxyphosphorylmethyl)benzoyl (when R2=phenyl).

[0010] This invention also provides a method for preparing 2,4,6-trimethylbenzoylphosphine oxide derivatives, comprising mixing halomethylated 2,4,6-trimethylbenzoylphosphine oxide with phosphites and performing an Arbuzov rearrangement reaction to obtain 2,4,6-trimethylbenzoylphosphine oxide derivatives, as shown in the following reaction formula:

[0011] Where X = Cl, Br, R1 = C n H 2n+1 (n=1~4), R2=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, OC n H 2n+1 (n=1~4), R3=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or 2,4,6trimethyl-3,5-bis(diethoxyphosphorylmethyl)benzoyl (when R2=phenyl).

[0012] Furthermore, the halomethylated 2,4,6-trimethylbenzoylphosphine oxide is prepared by halomethylation of 2,4,6-trimethylbenzoylphosphine oxide photoinitiator. The specific preparation method can be any of the methods reported in the prior art, such as the Blanc halomethylation reaction (paraformaldehyde / Lewis acid / solvent) or other reactions (such as Chinese patent CN110078761A, dibromodimethyl ether / anhydrous zinc bromide / solvent).

[0013] Furthermore, the molar ratio of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide to the phosphite is 1:1 to 1:20.

[0014] Furthermore, the molar ratio of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide to the phosphite is 1:1.5 to 1:6.

[0015] Furthermore, the Arbuzov rearrangement reaction of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide and phosphite is carried out at a temperature range of 90℃ to 150℃ and for a reaction time of 6 to 24 hours.

[0016] Furthermore, the Arbuzov rearrangement reaction of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide and phosphite is carried out at a temperature range of 100℃ to 110℃ and for a reaction time of 8 to 12 hours.

[0017] The phosphites mentioned include trimethyl phosphite, triethyl phosphite, tripropyl phosphite, or tributyl phosphite.

[0018] This invention also provides an application of a 2,4,6-trimethylbenzoylphosphine oxide derivative, which is used as a photoinitiator in photocurable inks, photocurable adhesives, photocurable coatings, fiber optic coatings, photoresists, dental fillers, or photocurable 3D printing, etc.

[0019] Furthermore, the amount of the 2,4,6-trimethylbenzoylphosphine oxide derivative added as a photoinitiator is 1~15wt%.

[0020] Furthermore, the 2,4,6-trimethylbenzoylphosphine oxide derivative is used as a photoinitiator to prepare the product, which is then cured by irradiation with a UV lamp or LED lamp in a nitrogen atmosphere for 1 to 10 seconds.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) Based on the structure of acylphosphine oxide photoinitiator 2,4,6-trimethylbenzoylphosphine oxide, this invention introduces a halomethyl group at the 3 or (and) 5 position of the benzene ring of trimethyl through further reaction to obtain a reactive intermediate. Further introduction of phosphate ester or other structures yields a series of photoinitiators with higher electron cloud density, which makes them stronger in ultraviolet absorption and improves initiation efficiency. The molecular weight of the products before and after photolysis increases, reducing the taste and migration problems in formulation applications.

[0022] (2) Due to numerous problems with existing 2,4,6-trimethylbenzoylphosphine oxide, researchers in the field, including the inventors, have attempted to modify TPO with various functional groups, but all have some problems, especially in terms of activity. Although there is an improvement, the overall activity improvement is not very significant due to the increased molecular weight. The 2,4,6-trimethylbenzoylphosphine oxide derivatives of the present invention have higher activity than the starting 2,4,6-trimethylbenzoylphosphine oxide, thanks to the introduction of two phosphoryl groups: in each phosphate ester, the positive charge of phosphorus is transferred through two alkoxy bonds, which significantly reduces the electron cloud density of neighboring groups. In addition, the synergistic effect of the conjugation effect of the phosphoryl groups further enhances its electron-withdrawing ability, thereby strengthening the reactivity of the free radical. Therefore, even if the molecular weight of the final product is much larger than that of the starting 2,4,6-trimethylbenzoylphosphine oxide photoinitiator, it still shows a significant activity advantage when used by the same weight.

[0023] The 2,4,6-trimethylbenzoylphosphine oxide derivatives of this invention exhibit improved resistance to yellowing. The photolysis products of the 2,4,6-trimethylbenzoylphosphine oxide derivatives of this invention, containing phosphorylbenzoyl and phosphonyl radicals, possess photobleaching properties during polymerization initiation, facilitating ultraviolet light transmission and making them suitable for curing thick coatings. This photobleaching effect further reduces yellowing of the coating during the curing process.

[0024] Generally speaking, if benzoyl free radicals fail to initiate double bond polymerization, they will produce some colored substances, such as benzaldehyde (usually yellow and with an irritating odor) formed after benzoyl free radicals abstract hydrogen, azobenzoyl (yellow) formed by the combination of two benzoyl free radicals, or semiquinones (yellow) formed by the reaction of two benzoyl free radicals.

[0025] The 2,4,6-trimethylbenzoylphosphine oxide derivatives of this invention have several advantages. Firstly, due to their high reactivity and large molecular weight, a smaller molar amount is required for the same mass, resulting in fewer free radicals and thus less dark-colored substances. Secondly, since all hydrogen atoms on the benzene ring of the benzoyl free radical are replaced by substituents, semiquinones cannot be formed. In other words, even if dark-colored substances are formed, their quantity is less than that of the initial 2,4,6-trimethylbenzoylphosphine oxide photoinitiator.

[0026] Therefore, the 2,4,6-trimethylbenzoylphosphine oxide derivative photoinitiator of the present invention is more resistant to yellowing than its initiating photoinitiator. (4) For the Blanc halomethylation reaction, the presence of a strongly electron-withdrawing phosphoryl group in the substrate 2,4,6-trimethylbenzoylphosphine oxide prevents electrophilic substitution reactions on the benzene ring attached to it. Simultaneously, the phosphoryl group reduces the electron-withdrawing ability of the carbonyl group in 2,4,6-trimethylbenzoyl, thus maintaining the electron cloud density on the benzene ring. Therefore, electrophilic substitution reactions only occur on the benzene ring of 2,4,6-trimethylbenzoyl. Furthermore, this reaction involves disubstituted products from the outset. Considering the difficulty in separating monosubstituted and disubstituted products, this invention does not consider monosubstituted reactions but instead uses an excess of electrophilic reagents (phosphites) to ensure complete disubstituted reactions. This not only achieves high yields but also facilitates the purification of the target product, simplifying the process and reducing costs.

[0027] The 2,4,6-trimethylbenzoylphosphine oxide derivatives of this invention exhibit strong reactivity and high initiation efficiency under both UV (high-pressure mercury lamp) and LED lamp conditions. During polymerization, the heat of reaction and the heat from the light source further raise the temperature of the polymerization system, thereby accelerating the polymerization reaction.

[0028] In addition, the entire synthesis process is simple, with few steps, easy to operate, and convenient to purify; its absorption spectrum has good overlap with the emission spectrum of inexpensive light sources such as LEDs, which is consistent with the development direction of UV curing technology. Attached Figure Description

[0029] Figure 1 These are before-and-after comparison images of the products obtained in Example 1 and Comparative Example 1 before and after irradiation; Figure 2 These are before-and-after comparison images of the products obtained in Example 2 and Comparative Example 2 before and after irradiation; Figure 3 The images show a comparison of the products obtained in Example 3 and Comparative Example 3 before and after irradiation. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0031] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available. Example 1

[0032] A 2,4,6-trimethylbenzoylphosphine oxide derivative is synthesized via the following route: ;

[0033] The specific preparation method is as follows: a. Preparation of diphenyl-[(2,4,6-trimethyl-3,5-dichloromethyl)-benzoyl]phosphine oxide (1a): In a 1000 mL four-necked flask equipped with a mechanical stirrer, thermometer, and constant-pressure funnel, 80 g (0.6 mol) of anhydrous aluminum trichloride, 12 g (0.4 mol) of paraformaldehyde, and 400 mL of dichloromethane were added sequentially. The mixture was cooled to -5°C and stirred until dissolved, forming a pale yellow solution. Separately, 69.6 g (0.2 mol) of TPO was dissolved in 100 mL of dichloromethane and added to the constant-pressure funnel, which was sealed with a liquid seal. The tail gas was absorbed with alkaline water. The solution was added slowly dropwise in the dark. The reaction system instantly changed from yellow to wine red, and gas was released. The addition was completed in 2-3 hours. After the addition was completed, the mixture was stirred for another 9 hours. The reaction was monitored using thin-layer chromatography (TLC) to determine the endpoint (developing solvent V). PE :V EA =5:3); After the reaction was complete, the wine-red reaction solution was slowly added to dilute hydrochloric acid in ice water to quench it. After stirring for 0.5 h, the solution was transferred to a separatory funnel for phase separation. The upper aqueous phase was extracted with 2×100 mL of dichloromethane. The organic phases were combined, washed with 3×100 mL of water, dried over anhydrous MgSO4, and filtered to remove solvent, yielding 88 g of a light yellow crude solid. 200 mL of petroleum ether was added and the mixture was stirred. After freezing and filtration, the product (1a) was dried, yielding 82.8 g of the target product (1a), with a melting point of 144-146℃. The purity of the product was 98.87% according to HPLC analysis, and the yield was 93%.

[0034] NMR analysis results of target product (1a): 1 H NMR (400 MHz, CDCl3): δ 8.06-8.01 (m, 4H, -C6H5), 7.64-7.53 (m, 6H, -C6H5), 4.61 (s, 4H, -CH2Cl), 2.51 (s, 3H, -C6-CH3), 2.07 (s, 6H, -C6-CH3).

[0035] b. Preparation of diphenyl-[(2,4,6-trimethyl-3,5-methylene phosphate diethyl ester)-benzoyl]phosphine oxide (2a): 20 g (0.044 mol) of 1a and 20 g (0.12 mol) of triethyl phosphite were added to a three-necked flask equipped with a magnetic stirrer. The mixture was heated to 100 °C in the dark and reacted for 8 h. The reaction was monitored by thin-layer chromatography (TLC) to determine the endpoint (evolving solvent V). PE V EA=1:5); after the reaction was complete, rotary evaporation was performed to obtain a light yellow solid, which was then recrystallized with petroleum ether / ethyl acetate to obtain the target product (2a), with a melting point of 114-118℃, an HPLC purity of 97.82%, and a final yield of 93.7%.

[0036] NMR analysis results of target product (2a): 1 H NMR (400 MHz, CDCl3): δ 8.07-8.02 (m, 4H, -C6H5), 7.61-7.50 (m, 6H, -C6H5), 4.06-3.85 (m, 8H, -C H 2CH3), 3.33-3.13 (t, 4H, -C6C H 2P(O)(OEt)2), 2.50-2.31 (s, 3H, -C6-CH3), 2.10-1.89 (s, 6H, -C6-CH3), 1.31-1.09 (m, 12H, -CH2C H 3). 31 P NMR (400 MHz, CDCl3): δ 26.5 (s, 2P, -CH2P(O)(OEt)2), 11.8 (s, 1P, -P(O)Ph2). Example 2

[0037] a. Preparation of diphenyl-[(2,4,6-trimethyl-3,5-dichloromethyl)-benzoyl]phosphine oxide (1a): Same as in Example 1.

[0038] b. Preparation of diphenyl-[(2,4,6-trimethyl-3,5-methylene dimethyl phosphate)-benzoyl]phosphine oxide (2b) ;

[0039] 20 g (0.044 mol) of 1a and 20 g (0.14 mol) of trimethyl phosphite were added to a three-necked flask equipped with a magnetic stirrer. The mixture was heated to 100 °C in the dark and reacted for 8 h. The reaction was stopped by thin-layer chromatography (TLC) to determine the endpoint (developing solvent V). PE V EA =1:5); after the reaction was complete, rotary evaporation was performed to obtain a light yellow solid, which was then recrystallized with petroleum ether / ethyl acetate to obtain the target product (2b), with a melting point of 155-158℃, an HPLC purity of 98.08%, and a yield of 89.4%. 1H NMR (400 MHz, CDCl3): δ 8.06-7.91 (m, 4H, -C6H5), 7.61-7.40 (m, 6H, -C6H5), 3.67-3.50 (d, 12H, -OCH3), 3.32-3.14 (d, 4H, -C6C H 2P(O)(OMe)2), 2.50-2.36 (s, 3H, -C6-CH3), 2.04-1.86 (s, 6H, -C6-CH3). 31 P NMR (400 MHz, CDCl3): δ 28.6 (s, 2P, -CH2P(O)(OMe)2), 12.2 (s, 1P, -P(O)Ph2). Example 3

[0040] a. Preparation of bis(4-methyl-phenyl)-[(2,4,6-trimethyl-3,5-dichloromethyl)-benzoyl]phosphine oxide (1b): The same molar amount of TPO was replaced with TMO, and the procedure was performed as in Example 1. A pale yellow solid was obtained in 93% yield, with an HPLC purity of 98.23% and a melting point of 75-80 °C. NMR data: 1 H NMR (400 MHz, CDCl3): δ 7.91-7.83 (m, 4H, -C6H4), 7.36-7.28 (m, 4H, -C6H4), 4.60 (s, 4H, -CH2Cl), 2.37 (s, 6H, -C6H4-CH3), 2.16-1.92 (s, 9H, -C6-CH3).

[0041] b. Preparation of diphenyl-[(2,4,6-trimethyl-3,5-methylene phosphate dimethyl ester)-benzoyl]phosphine oxide (2c)

[0042] 20 g (0.041 mol) of 1b and 20 g (0.12 mol) of triethyl phosphite were added to a three-necked flask equipped with a magnetic stirrer. The mixture was heated to 100 °C in the dark and reacted for 8 h. The reaction was monitored by thin-layer chromatography (TLC) to determine the endpoint (evolving solvent V). PE V EA =1:5); after the reaction was complete, rotary evaporation was performed to obtain a light yellow solid, which was then recrystallized with petroleum ether / ethyl acetate to obtain 26 g of the target product (2c), which is a light yellow solid with a melting point of 110-115℃. The purity of the product was 98.19% by liquid chromatography and the yield was 91.5%. 1 H NMR (400 MHz, CDCl3): δ 7.91-7.87 (m, 4H, -C6 H4Me), 7.32-7.28 (m, 4H, -C6 H 4Me), 3.99-3.96 (m, 8H, -OC H 2CH3), 3.22-3.21 (d, 4H, -C H 2P(O)(OEt)2), 2.48-2.39(m, 15H, -C6-CH3), 1.37-1.19 (m, 12H, -OCH2C H 3). 31 P NMR (400 MHz, CDCl3): δ 26.5 (s, 2P, -CH2P(O)(OEt)2), 12.8 (s, 1P, -P(O) (PhMe)2).

[0043] Application Example 1 The 2,4,6-trimethylbenzoyl-diphenylphosphine oxide derivatives 2a, 2b, and 2c obtained in Examples 1-3 were used as photoinitiators for photoinitiated polymerization. The specific method is as follows: Accurately weigh 9.5 g of THFA (tetrahydrofurfuryl acrylate), 9.5 g of TPGDA (tripropylene glycol diacrylate), and 1 g of photoinitiator. Mix the above materials thoroughly, take 2.2 g, place it in a PE self-sealing bag (80 mm × 110 mm), purge with nitrogen to remove the gas, seal the bag, and sandwich it between two glass plates to form a flat liquid film. Place it in a UV / LED curing machine (OSM-UV-4808TB model, OSM Machinery Equipment Co., Ltd.), with the length direction aligned with the conveyor direction. Adjust the conveyor belt speed to 6 m / min, which translates to approximately 1 second of light exposure.

[0044] The testing process and results are shown in Table 1 below: Table 1. Curing of photoinitiators under different light sources and energy densities.

[0045] As shown in Table 1 regarding the curing results, under the same formulation ratio, light source, and light intensity, the photoinitiated polymerization rate of the TPO derivative in this invention is significantly higher than that of TPO. The photoinitiated polymerization rate of the TMO derivative is slightly faster than that of TMO, but both are significantly faster than TPO and its derivatives. Based on the above, and considering that the molecular weights of the corresponding derivatives are all greater than (approximately 1.8 times) the molecular weight of the starting photoinitiator, it indicates that the activity of the free radicals generated by photolysis (mainly the trimethylbenzoyl free radical containing a phosphonyl group, since the other half of the free radical is the same) is higher than that of the trimethylbenzoyl free radical without a phosphonyl group.

[0046] Application Example 2 The products obtained in Examples 1-3 were subjected to polymerization performance tests for the initiator unsaturated monomer trimethylolpropane triacrylate (TMPTA), initiator migration rate after curing, and odor tests. The specific test method was as follows: a 2 wt% initiator-TMPTA curing solution was prepared (i.e., the products obtained in Examples 1-3 were mixed with TMPTA as the initiator), and the solution was coated onto a smooth glass plate (200 μm thick) and irradiated with an LED@365 light source (600 mJ / cm²). 2 The reaction was considered complete when the film was no longer sticky to the touch after pressing, and the curing time was recorded. The migration rate was then measured. The migration rate test method was as follows: the film obtained by photocuring was scraped off with a spatula and crushed into powder. A certain weight of the film powder was weighed and added to 5 mL of acetonitrile. After stirring for 48 h, the mixture was filtered to obtain the extract, which was then diluted to 10 mL. The absorbance of the extract was measured, and the concentration of the photoinitiator extract was calculated according to the Lambert-Beer formula. The photoinitiator migration rate was then calculated according to the following formula: Migration rate = (I × Iw × I) / (I × I × I) × 100% Where A is the absorbance of the extract at the maximum absorption wavelength of the photoinitiator, Mw is the molecular weight of the photoinitiator, V is the volume of the extract, ε is the molar extinction coefficient at the maximum absorption wavelength of the photoinitiator, l is the optical path length (1 cm), m0 is the mass of the cured film powder, and b is the mass percentage of the photoinitiator.

[0047] Comparative Example 1 Under the same conditions as in Application Example 2, commercially available TPO was used as the photoinitiator to replace the photoinitiator 2a prepared in Example 1.

[0048] Comparative Example 2 Under the same conditions as in Application Example 2, the photoinitiator (1c) prepared in Example 1 of patent application CN116731067A was used to replace the photoinitiator 2a prepared in Example 1.

[0049] Comparative Example 3 Under the same conditions as in Application Example 2, commercially available TMO was used as the photoinitiator to replace the photoinitiator 2a prepared in Example 1.

[0050] The performance test results of the initiators obtained in Examples 1-3 and Comparative Examples 1-3 are shown in Table 2 below: Table 2. Curing speed, migration rate and odor of different photoinitiators

[0051] As can be seen from Table 2, the 2,4,6-trimethylbenzoylphosphine oxide derivatives prepared in Examples 1-3, when used as photoinitiators to initiate the curing reaction of TMPTA, all exhibited faster curing speeds and lower migration rates than the initial 2,4,6-trimethylbenzoylphosphine oxide initiators synthesized from them. TPO and TMO, when used as photoinitiators, exhibited aldehyde odors after curing.

[0052] Application Example 3 Yellowing resistance tests were conducted on the products obtained in Examples 1-3 and Comparative Examples 1-3. Specifically, the products obtained in Examples 1-3 and Comparative Examples 1-3 were used as initiators and dissolved with monomers (hexanediol diacrylate, Jiangsu Litian Technology Co., Ltd.) and UV-curable resins (CN9010NS, Sartoma (Guangzhou) Chemical Co., Ltd.) in a ratio of 5:20:75 (by weight). 5 grams of the solution was weighed and placed in a transparent plastic disc (the top of a disposable cup cut off). Curing was performed on a UV curing machine (manufactured by Shanghai Zhenhui Optoelectronic Technology Co., Ltd., model C20033AU1G1). The light source was a high-pressure mercury lamp, and the energy density was set to 250 mJ / cm³. 2 Irradiate the sample multiple times as needed, and observe the curing and yellowing of the sample.

[0053] like Figure 1 The image shows the changes in the samples obtained in Example 1 and Comparative Example 1 after the above experiments, before light exposure and after three irradiations (2 seconds each, with a 5-minute interval between irradiations). Figure 1 It can be seen that the sample obtained in Example 1 will also turn yellow after repeated UV irradiation, but the color is lighter than that of TPO, and the final color is still light yellow with high transparency. In contrast, the product obtained in Comparative Example 1 gradually turns yellow after repeated UV irradiation, and finally becomes yellowish-red.

[0054] like Figure 2 The image shows the changes in the samples obtained in Example 2 and Comparative Example 2 after the above experiments, before light exposure and after three irradiations (2 seconds each, with a 5-minute interval between irradiations). Figure 2 It can be seen that the sample obtained in Example 2 still has high transparency after multiple irradiations, while the product obtained in Comparative Example 2 turns yellow and slightly reddish after three irradiations.

[0055] like Figure 3 As shown, the above experiments were conducted on the products obtained in Example 3 and Comparative Example 3. At a dosage of 5%, the reaction was extremely vigorous, to the point that the heat of reaction burned the plastic cup. Increasing the dosage to 2% moderated the reaction, but it was still rapid, with significant heat generation. With increasing UV irradiation times, the color of both products gradually deepened, slowly changing from colorless to pale yellow. The final color of the product in Comparative Example 3 had a slight reddish tint, while the product in Example 3 was ultimately pale yellow.

[0056] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any 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 invention should be within the protection scope of the present invention.

Claims

1. A 2,4,6-trimethylbenzoylphosphine oxide derivative, characterized in that, It has the following structural formula: ； Where R1=C n H 2n+1 (n=1~4), R2=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or OC n H 2n+1 (n=1~4), R3=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or 2,4,6trimethyl-3,5-bis(diethoxyphosphorylmethyl)benzoyl.

2. A method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative as described in claim 1, characterized in that, A mixture of halomethylated 2,4,6-trimethylbenzoylphosphine oxide and phosphites was subjected to the Arbuzov rearrangement reaction to yield the 2,4,6-trimethylbenzoylphosphine oxide derivative, as shown in the following reaction formula: ； R1=C n H 2n+1 (n=1~4), R2=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or OC n H 2n+1 (n=1~4), R3=phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl or 2,4,6trimethyl-3,5-bis(diethoxyphosphorylmethyl)benzoyl.

3. The method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 2, characterized in that, The halomethylated 2,4,6-trimethylbenzoylphosphine oxide is prepared by halomethylation of a 2,4,6-trimethylbenzoylphosphine oxide photoinitiator.

4. The method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 2, wherein the molar ratio of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide to the phosphite is 1:1 to 1:

20.

5. The method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 2 or 4, wherein the molar ratio of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide to the phosphite is 1:1.5 to 1:

6.

6. The method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 2, characterized in that, The Arbuzov rearrangement reaction of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide and phosphites is carried out at a temperature range of 90℃ to 150℃ and for a reaction time of 6 to 24 hours.

7. A method for preparing a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 2 or 6, characterized in that, The Arbuzov rearrangement reaction of the halomethylated 2,4,6-trimethylbenzoylphosphine oxide and phosphites is carried out in the temperature range of 100℃~110℃ and the reaction time is 8~12h.

8. An application of a 2,4,6-trimethylbenzoylphosphine oxide derivative as described in claim 1, characterized in that, The 2,4,6-trimethylbenzoylphosphine oxide derivatives are used as photoinitiators in photocurable inks, photocurable adhesives, photocurable coatings, fiber optic coatings, photoresists, dental fillers, or photocurable 3D printing.

9. The application of a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 8, characterized in that, The amount of the 2,4,6-trimethylbenzoylphosphine oxide derivative added as a photoinitiator is 1~15wt%.

10. The application of a 2,4,6-trimethylbenzoylphosphine oxide derivative according to claim 8, characterized in that, The 2,4,6-trimethylbenzoylphosphine oxide derivatives are used as photoinitiators to prepare products that are cured by light irradiation in a nitrogen atmosphere for 1 to 10 seconds.

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