CN117658914A - Naphthalimide photoinitiator, photopolymerizable liquid composition, method and application - Google Patents

Abstract

The invention discloses a naphthalimide photoinitiator, which has a structure shown in the following general formula I: in the general formula I, R ₁ The structure of (2) is shown as a general formula II, wherein in the general formula II, n is an arbitrary positive integer; r is R ₂ Selected from Br, H, NH ₂ One of substituted or unsubstituted phenyl, aziridine, azetidine, tetrahydropyrrole, morpholine, piperidine, hexamethyleneimine or dimethylamine; r is R ₃ A substituent selected from the group consisting of an indefinite position on the benzene ring. The naphthalimide photoinitiator disclosed by the invention is based on diethylamino benzonaphthalimide crossed between spin orbit charge transfer systems, and can realize effective visible light polymerization under the condition of no heavy atoms.

Description

Naphthalimide photoinitiator, photopolymerizable liquid composition, method and application

Technical field

The present invention relates to the field of photocurable materials, and in particular to a type of naphthalimide photoinitiator, its preparation method and application, and a photopolymerizable liquid containing the photoinitiator.

Background technique

Traditional curing technology mainly relies on thermosetting technology, which is usually performed in an autoclave or high-temperature oven (~200°C), which is characterized by low energy efficiency. However, limitations in size, energy, and material costs pose significant challenges to the development of future curing materials. Therefore, there is a new demand for curing technology that is environmentally friendly, efficient, and not limited by space or time. Photocuring refers to the process in which a monomer or oligomer is transformed from a liquid state to a solid state through a photoinitiator under the irradiation of light. It has the advantages of high efficiency, environmental protection, energy saving, etc., and has superior spatial and temporal selectivity. Generally speaking, the photocuring process usually includes a light source, a photoinitiator (PI) and a polymerizable medium. Compared with traditional mercury lamps, visible light-emitting diodes (LEDs) with negligible radiation, harmlessness, low cost, and high efficiency have been more extensively studied. However, the absorption of PIs is difficult to match the narrow wavelength range of LED lamps, resulting in low excitation efficiency. In addition, according to the type of initiation mechanism, PI can be divided into radical PI and cationic PI. Compared with cationic PI, free radical PI has the advantages of fast initiation, simple preparation, and low price. Therefore, visible light triggered free radical initiators are more suitable for photocuring.

According to its mechanism of action on photopolymerization (FRP), free radical PI can generally be divided into type I and type II. Type I initiators undergo homolytic cleavage of chemical bonds under irradiation and generate active free radicals for polymerization. During this process, such initiators inevitably produce toxic cleavage products, pungent odors and volatile substances, which have a harmful impact on the environment. The hydrogen transfer mechanism of type II free radical photoinitiator avoids the possibility of homolytic cleavage of type I free radical photoinitiator to produce cracking fragments, making it safer and more environmentally friendly. However, type II photoinitiation suffers from low hydrogen transfer efficiency. The electron/hydrogen extraction efficiency involved in the hydrogen transfer mechanism needs to be improved by increasing the excited state lifetime and shortening the donor-acceptor distance. So far, a common strategy is to add heavy atoms (such as Pt, Ir, Ru, Br and I) to the chromophore to improve its efficiency in generating triplet excited states. However, this method results in low solubility of the initiator, poor photostability, and large cytotoxicity, limiting practical applications. Heavy-atom-free spin-orbit charge transfer intersystem crossover SOCT-ISC can occur in molecules with significant charge transfer (CT) properties and can also increase triplet yields. Based on the above, in order to improve the intersystem jump (ISC) efficiency and shorten the donor-acceptor distance, it is very necessary to develop and design efficient photoinitiators that self-donate hydrogen without heavy atoms to promote the processing of new materials.

Contents of the invention

In view of the problems that photoinitiators in the prior art rely on heavy atoms doped with precious metals or toxic halogens, resulting in increased dark toxicity, short three-state life, and poor photostability, the present invention provides a type of naphthalimide photoinitiator , diethylaminophenylinobinaphthimide based on interspin-orbital charge transfer system crossover, enables efficient visible light polymerization without heavy atoms.

In order to achieve the above object, the technical solution of the present invention is: a kind of naphthalimide photoinitiator, the structure of which is shown in the general formula I:

In general formula I,

The structure of R ₁ is shown in the general formula II. In the general formula II, the value of n is any positive integer;

R ₂ is selected from Br, H, NH ₂ , substituted or unsubstituted phenyl, aziridine, azetidine, tetrahydropyrrole, morpholine, piperidine, hexamethyleneimine or dimethylamine a kind of;

R ₃ is selected from substituents at an indefinite position on the benzene ring.

Further, the substituent indicated in the substituted phenyl group is selected from H, OH, SH, NH ₂ , NO ₂ , CN, COOH, C _1-8 alkoxy group, C _1-8 alkylamino group, C One of _1-8 amide group, halogen or C _1-8 haloalkyl group;

The substituent at an indefinite position of the benzene ring is selected from the group consisting of H, OH, SH, NH ₂ , NO ₂ , CN, COOH, C _1-8 alkoxy group, C _1-8 alkylamino group, and C _1-8 amide group. , halogen or one of C _1-8 haloalkyl.

Further, in general formula II, n takes a value of 1, 2 or 3;

The R ₂ is selected from aziridine, morpholine, piperidine or dimethylamine.

Containing the initiator of the imide dye, the photopolymerizable liquid composition includes 0.01-0.1wt% naphthalimide photoinitiator, and the balance is tripropylene glycol diacrylate;

Or it is composed of an amine compound, an onium salt compound and a naphthalimide photoinitiator, in which the weight of the naphthalimide photoinitiator accounts for 0.1-5wt% of the initiator, and the weight of the amine compound is naphthalimide photoinitiator. 1-10 times the weight of the agent, and the balance is onium salt compounds.

Further, the amine compound is selected from L-phenylglycine, N-phenylglycine, 2-amino-2-phenylacetic acid, N-(2-carboxy)phenylglycine, N-phenyl-N- One or Any combination.

Further, the onium salt compound is selected from one or any combination of iodonium salt compounds and sulfonium salt compounds.

Furthermore, the iodonium salt compound is selected from diphenyliodonium hexafluorophosphate, bis(tert-butylphenyl)iodonium hexafluorophosphate, bis(p-tolyl)iodonium hexafluorophosphate, triaryl One or any combination of iodonium salts, diaryliodonium salts, and alkyliodonium salts;

The sulfonium salt compound is selected from one or any combination of triarylsulfonium salts, diarylsulfonium salts, and alkylsulfonium salts.

The preparation method of naphthalimide photoinitiator includes the following steps:

(1) Under an inert atmosphere, 4-bromo-1,8-naphthalenedicarboxylic anhydride containing R ₃ substitution and aniline containing R ₁ substitution are refluxed in an organic solvent for 3-12 hours. The reaction temperature is 120°C; the preferred time Determined according to different reaction processes;

(2) Under an inert atmosphere, react the compound prepared in step (1) with compound R ₂ in a reaction solvent under reflux for 3-12 hours at a reaction temperature of 125°C to obtain the target product;

The process is as follows:

Further, in step (1), the molar ratio of 4-bromo-1,8-naphthalenedicarboxylic anhydride containing _R3 substitution to the aniline containing _R1 substitution is 1:1-4; the preferred molar ratio is 1:1- 2;

The organic solvent is selected from at least one of absolute ethanol, acetic acid or formic acid; ethanol is preferred.

Further, in step (2), the molar ratio of the compound prepared in step (1) to compound _R2 is 1:1-1:1.5; the optimal molar ratio is 1:1.5;

The reaction solvent is selected from dimethyl sulfoxide, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, acetonitrile, chlorobenzene, dichlorobenzene, anisole, and petroleum Ether, dioxane, tetrahydrofuran, pyridine, N,N-dimethylformamide, N-methylpyrrolidone, methyl tert-butyl ether, ethylene glycol dimethyl ether, acetone, methyl ethyl ketone, methanol, ethanol or At least one of propanol, the optimal solvent is ethylene glycol monomethyl ether.

The application of the naphthalimide photoinitiator in the field of photocuring technology has low cytotoxicity and is conducive to promoting the application of coatings, inks or 3D printing in food packaging and biomedicine.

Further, the main material cured in the photocuring technology described in this application is selected from the group consisting of acrylate monomers, including diethylene glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and triethylene glycol. Diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, tetraethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, diacrylate At least one of pentaerythritol hexaacrylate, 1,6-hexanediol diacrylate, and trimethylolpropane triacrylate.

To sum up, the present invention has the following beneficial effects:

First, the imine derivative provided in this application has a D (electron donor)-T (conjugated electron bridge)-A (electron acceptor) structure. This application uses ·diethylamino· as the electron acceptor, and · -Ph-R· serves as the electron donor, with the coumarin core serving as the bridge. Density function theory analysis shows that HOMO electrons are mainly distributed in diethylamine, and LUMO electrons are mainly distributed in the bridge and electron acceptor positions. , indicating that intramolecular charge transfer can occur, causing the absorption peak to be red-shifted and its absorption peak to be in the visible light region, which is suitable for LED light sources;

Second, since the hydrogen donor and hydrogen acceptor are in the same core structure, the photoinitiation activity is high. Experiments have proven that only 0.05wt% can make the acrylate monomer polymerization rate about 90%;

Third, it contains an auxiliary initiator group and can initiate polymerization without adding auxiliaries;

Fourth, low toxicity, green and environmentally friendly.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is the ultraviolet-visible (UV-Vis) spectrum of the photoinitiators disclosed in Examples 1-5 of the present invention. The concentrations are all 1×10 ^-5 mol/L, and the test system is an acetonitrile solution;

Figure 2 is a diagram showing the absorbance changes of the photoinitiators disclosed in Examples 1-5 of the present invention under LED irradiation with a wavelength of 405 nm. The concentration of the photoinitiator molecules is 1×10 ^-5 mol/L, and the LED light intensity is 100mW/cm. ² ;

Figure 3 is a schematic diagram of the thermal stability of the photoinitiators disclosed in Examples 1-5 of the present invention under nitrogen protection;

Figure 4 is a schematic diagram of the curing conversion rate of the single-component photopolymerizable liquid containing the photoinitiator of Examples 1-5 disclosed in the present invention;

Figure 5 is a schematic diagram of the curing conversion rate of the multi-component photopolymerizable liquid containing the photoinitiator of Examples 1-5 disclosed in the present invention;

Figure 6 is the kinetic curve of photopolymerization of TPGDA monomer by mixed NPG/IOD at the optimal concentration, where the measurement unit of initiator/co-initiator is the percentage relative to the monomer mass. The irradiation wavelength is 405nm, and the optical density is 100mW/cm ² .

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

The purification method of the naphthalimide photoinitiator of the present invention adopts conventional methods and is not particularly limited. Usually, after completion, add a small amount of solvent to precipitate.

The naphthalimide photoinitiator represented by the general formula I will be described in detail below with reference to examples.

A type of naphthalimide photoinitiator, its structure is shown in the general formula I:

In general formula I,

R ₁ is selected from the structure shown in the general formula II or -OC _n H _m , the values of n and m are any positive integers;

R ₂ is selected from Br, H, NH ₂ , substituted or unsubstituted phenyl, aziridine, azetidine, tetrahydropyrrole, morpholine, piperidine, hexamethyleneimine or dimethylamine a kind of;

R ₃ is selected from substituents at an indefinite position on the benzene ring.

Preferably, R ₂ is selected from -N(CH ₃ ) ₂ , -N(CH ₂ CH ₃ ) ₂ , -NCH ₃ C ₄ H ₈ CH ₃ , -Ph-OCH ₃ or -Ph-OC ₃ H ₇ ;

Specific examples of the compound represented by the general formula I are given below, but the present invention is not limited to these specific examples.

The general synthesis process of the compound represented by the general formula I of the present invention is as follows:

The compound represented by the general formula I of the present invention can be synthesized by the method described below

Example

Example 1

A type of N-Br naphthalimide photoinitiator has the following structural formula:

Its preparation method includes the following steps:

4-Bromo-1,8-naphthoic anhydride (3.26g, 11.78mmol) was added to a 100ml double clean bottle and dissolved in 25mL of ethanol. Stir for 10 minutes and add N,N-diethyl-p-phenylenediamine (2.52g, 15.5mmol). Subsequently, it was refluxed for 2.5 hours under a nitrogen atmosphere. After the mixture was cooled overnight, a large number of needle-like crystals precipitated and were washed with water several times to obtain a brown solid, 4.6 g, with a yield of 93.6%, named N-Br.

The hydrogen nuclear magnetic spectrum data of the photoinitiator N-Br are:

¹ HNMR (400MHz, CDCl3) δ8.70 (dd, J＝7.3, 1.1Hz, 1H), 8.61 (dd, J＝8.5, 1.1Hz, 1H), 8.46 (d, J＝7.8Hz, 1H), 8.06 (d,J＝7.8Hz,1H),7.87(dd,J＝8.5,7.3Hz,1H),7.14–7.06(m,2H),6.81–6.74(m,2H),3.40(q,J＝7.1 Hz, 4H), 1.20 (t, J = 7.0Hz, 6H).

The mass spectrum data of the photoinitiator N-Br are: m/z calculated C ₁₉ H ₁₈ BrNO ₂ [M+H] ⁺ :422.0630, test: 423.03.

Example 2

A type of N-PD naphthalimide photoinitiator has the following structural formula:

Its preparation method includes the following steps:

The NP-Br (4.22g, 10mmol) prepared in Example 1 was placed in a 100ml double-necked flask, 40mL of ethylene glycol monomethyl ether was added as the solvent, and 0.5mL of piperidine was added. Subsequently, it was refluxed for 3 hours under a nitrogen atmosphere. After the reaction was completed, it was purified by petroleum ether/dichloro column chromatography to obtain the target product, named N-PD, 3.98 g, with a yield of 93.2%. And carry out structural identification through mass spectrometry and nuclear magnetic resonance spectroscopy;

The hydrogen nuclear magnetic spectrum data of the photoinitiator N-PD are:

¹ HNMR (400MHz, CDCl ₃ ) δ8.61(d,J＝7.3Hz,1H),8.53(d,J＝8.1Hz,1H),8.42(d,J＝8.4Hz,1H),7.69(t, J＝7.8Hz,1H),7.20(d,J＝8.1Hz,1H),7.10(d,J＝8.4Hz,2H),6.76(d,J＝8.4Hz,2H),3.39(q,J＝ 7.1Hz,4H),3.24(q,J＝6.4Hz,4H),1.90(p,J＝5.5Hz,4H),1.74(d,J＝6.6Hz,2H),1.19(t,J＝7.0Hz ,6H).

The mass spectrum data of photoinitiator N-PD are: m/z calculated for C ₂₇ H ₂₉ N ₃ O ₂ [M+H] ⁺ :427.2260, test: 428.2339.

Example 3

A type of N-ML naphthalimide photoinitiator has the following structural formula:

The only difference from Example 2 is that the solvent R ₂ is different, specifically,

The NP-Br (4.22g, 10mmol) provided in Example 1 was placed in a 100mL double-necked flask, 40mL of ethylene glycol monomethyl ether was added as the solvent, and 0.5mL of morpholine was added. Subsequently, it was refluxed for 3 hours under a nitrogen atmosphere. After the reaction was completed, it was purified by petroleum ether/dichloro column chromatography to obtain the target product, named N-ML, 3.79 g, with a yield of 88.3%. And carry out structural identification through mass spectrometry and nuclear magnetic resonance spectroscopy;

The hydrogen nuclear magnetic spectrum data of photoinitiator N-ML are:

¹ HNMR (400MHz, CDCl ₃ ) δ8.63(d,J＝7.2Hz,1H),8.57(d,J＝8.0Hz,1H),8.46(d,J＝8.4Hz,1H),7.73(t, J＝7.8Hz,1H),7.24(d,J＝7.8Hz,1H)7.10(d,J＝8.4Hz,2H),6.77(d,J＝8.4Hz,2H),4.04(t,J＝4.5 Hz, 4H), 3.40 (q, J = 7.1Hz, 4H), 3.29 (t, J = 4.5Hz, 4H), 1.20 (t, J = 7.0Hz, 6H).

The mass spectrum data of photoinitiator N-ML are: m/z calculated for C ₂₆ H ₂₇ N ₃ O ₃ [M+H] ⁺ :427.2260, test: 428.2339.

Example 4

A type of NP-ML naphthalimide photoinitiator has the following structural formula:

Its preparation method includes the following steps:

(1) Add 4-bromo-1,8-naphthoic anhydride (3.26g, 11.78mmol) into a 100ml double clean bottle and dissolve it in 25mL of ethanol. Stir for 10 minutes and add aniline (1.457g, 15.5mmol). Subsequently, it was refluxed for 2.5 hours under a nitrogen atmosphere. After the mixture was cooled overnight, a large number of needle-like crystals precipitated and were washed with water several times to obtain a brown solid, named NP-Br, 4.05 g, with a yield of 96%.

(2) Place the NP-Br (3.51g, 10mmol) prepared in step (1) into a 100mL double-necked flask, add 40mL ethylene glycol monomethyl ether as the solvent, and add 0.5mL morpholine. Subsequently, it was refluxed for 3 hours under a nitrogen atmosphere. After the reaction was completed, it was purified by petroleum ether/dichloro column chromatography to obtain the target product, named NP-ML, 3.16 g, with a yield of 88.3%. And carry out structural identification through mass spectrometry and nuclear magnetic resonance spectroscopy;

The hydrogen nuclear magnetic spectrum data of photoinitiator NP-ML are:

¹ HNMR (400MHz, DMSO) δ8.56 (dd, J＝8.5, 1.3Hz, 1H), 8.49 (dd, J＝7.3, 1.2Hz, 1H), 8.42 (d, J＝8.1Hz, 1H), 7.85 (dd,J＝8.5,7.2Hz,1H),7.56–7.49(m,2H),7.48–7.42(m,1H),7.40(d,J＝8.1Hz,1H),7.38–7.33(m,2H ),3.93(t,J＝4.5Hz,4H),3.30–3.22(m,4H).

The mass spectrum data of photoinitiator NP-ML is: m/z calculated for C ₂₂ H ₁₈ N ₂ O ₃ [M+H] ⁺ :358.1317, tested: 359.1393.

Example 5

A type of NOP-ML naphthalimide photoinitiator has the following structural formula:

Its preparation method includes the following steps:

(1) 4-Bromo-1,8-naphthoic anhydride (3.26g, 11.78mmol) was added to a 100ml double clean bottle and dissolved in 25mL of ethanol. Stir for 10 minutes and add p-methoxyaniline (1.922g, 15.5mmol). Subsequently, it was refluxed for 2.5 hours under a nitrogen atmosphere. After the mixture was cooled overnight, a large number of needle-like crystals precipitated and were washed with water several times to obtain a brown solid, named NOP-Br, 3.95 g, with a yield of 88%.

(2) Place the NOP-Br (3.81g, 10mmol) provided in step (1) into a 100mL double-necked flask, add 40mL ethylene glycol monomethyl ether as the solvent, and add 0.5mL morpholine. Subsequently, it was refluxed for 3 hours under a nitrogen atmosphere. After the reaction was completed, it was purified by petroleum ether/dichloro column chromatography to obtain the target product, named NOP-ML, 3.58 g, with a yield of 92.3%. And carry out structural identification through mass spectrometry and nuclear magnetic resonance spectroscopy;

The hydrogen nuclear magnetic spectrum data of photoinitiator NOP-ML are:

¹ HNMR (400MHz, DMSO) δ8.55 (dd, J＝8.4, 1.2Hz, 1H), 8.48 (dd, J＝7.3, 1.1Hz, 1H), 8.42 (d, J＝8.1Hz, 1H), 7.85 (dd,J＝8.4,7.3Hz,1H),7.40(d,J＝8.1Hz,1H),7.28–7.22(m,2H),7.08–7.03(m,2H),3.97–3.89(m,4H ),3.83(s,3H),3.25(t,J＝4.5Hz,4H).

The mass spectrum data of photoinitiator NOP-ML are: m/z calculated for C ₂₃ H ₂₀ N ₂ O ₄ [M+H] ⁺ :388.1423, tested: 389.1495.

test case

Test example 1

In order to prove that the naphthalimide photoinitiator prepared in Examples 1-5 has low cytotoxicity in the field of photocuring technology and is conducive to promoting the application of coatings, inks or 3D printing in food packaging and biomedicine, The naphthalimide photoinitiator prepared in Examples 1-5 was prepared into a 1×10 ^-5 mol/L naphthalimide solution using dichloromethane for the following tests:

(1)Absorption test

The absorbance of the compound solutions of Examples 1-5 was tested using a UV spectrophotometer, and the test results are shown in Figure 1.

As can be seen from Figure 1, the absorption range of N-Br is 250~375nm, while the absorption peaks of N-PD, N-ML, NP-ML, and NOP-ML cover 350~475nm. The purpose is to illustrate the change of position 2 When the electron-donating group is introduced, the absorption will be red-shifted. Compared with N-ML, NP-ML, and NOP-ML, changing the group at position 1 will not cause significant changes in the initiator.

(2) Steady-state photolysis test

Take 2mL of naphthalimide dichloromethane solution and place it in a cuvette and illuminate it under different LED light sources (light intensity 100mW/cm ² ). Use a UV spectrophotometer to test the absorbance change of the solution at different times. The test results are shown in Figure 2 middle.

As can be seen from Figure 2, as the illumination time increases, the absorption peak of the photoinitiator molecules gradually decreases. Compared with NP-ML and NOP-ML, N-PD and N-ML photodegrade slowly, indicating that the R ₁ group is changed. group, which is beneficial to adjusting the photostability of the photoinitiator. N-PD and N-ML have better photostability and are beneficial to photoinitiation.

(3) Photoinduced thermal stability test

The thermogravimetric method was used to evaluate the thermal stability of synthetic dyes. The synthetic dyes were heated from 50°C to 600°C at a heating rate of 10°C/min under nitrogen protection, and their thermal decomposition temperature was determined based on a weight loss of 5wt%. Heated from 50°C to 100°C at a heating rate of 10°C/min and kept for 10 min, and continued to increase the temperature to 600°C at a rate of 10°C/min. The test results are shown in Figure 3.

As can be seen from Figure 3, the temperature at which N-PD, N-ML, NP-ML, and NOP-ML lose 5wt% of their thermal weight is about 400°C. When the thermal weight loss is 50wt%, N-PD, N-ML, NP- The temperature of ML and NOP-ML is 450℃. The developed initiator has good thermal stability and is easy to store and transport.

Test example 2

In order to prove that the naphthalimide photoinitiator prepared in Example 2-5 as a photoinitiator can initiate polymerization in the environment without adding additives under the irradiation of a 405nm LED light source; the initiation activity is two times higher than that of existing photoinitiators. Initiators such as benzophenone and naphthalimide are high.

(1) Configure a one-component photosensitive liquid containing naphthalimide photoinitiator, and its ratio is:

A: Tripropylene glycol diacrylate (99.99%-99.90% mass)

B: The initiator includes 0.01-0.1wt% naphthalimide photoinitiator

(2) Configure a composite component photosensitive liquid containing naphthalimide photoinitiator, and its ratio is:

It consists of amine compounds, onium salt compounds and naphthalimide photoinitiator, in which the weight of naphthalimide photoinitiator accounts for 0.05wt% of the initiator, and the weight of amine compound is the weight of naphthalimide photoinitiator. 1-10 times the weight of the onium salt compound is 1-10 times the weight of the naphthalimide photoinitiator, and the balance is TPGDA monomer. Preferably, the amine compound is selected from amine N-phenylglycine, and the onium salt compound is selected from diphenyliodonium hexafluorophosphate.

(3) Photoinitiation ability test of single-component photosensitive liquid

Mix tripropylene glycol diacrylate in (1) with the compounds prepared in Examples 1-5 (0.03wt%, 0.05wt%, 0.1wt%) respectively, obtain a uniform resin mixture through ultrasonic vibration and mechanical stirring, and prepare a photocurable formula. Based on the FRP process, the studied resin was coated on a thin KBr sheet (thickness = 2 mm). It is then covered with another glass piece and photopolymerized. After irradiation, the decrease in the double bond content of TPGDA was monitored using a Nicolet5700 FT-IR spectrometer. The test results are shown in Figure 4, Figure 5 and Figure 6.

Figure 4 is a schematic diagram of the curing conversion rate in step (3). The purpose is to illustrate that single-component N-ML still has ultra-high photoinitiation ability. As can be seen from Figure 4, when N-PD/N-ML is used alone, only It only takes 0.03wt% to initiate curing. When it continues to increase to 0.05wt%, the acrylate double bond conversion rate can reach 85%. When increased to 0.1wt%, the conversion rate is nearly 90%.

Figure 5 is a schematic diagram of the curing conversion rate of Examples 1-5. The purpose is to illustrate that the developed initiator has excellent effect. Only a dosage of 0.05wt% can exceed the commercially available type II BP photoinitiator (a dosage of 0.3%, Anaiji, 99 %pure).

As can be seen from Figure 6, if N-PD/N-ML (0.05wt%) is the same as commercially available NPG/IOD (0.3wt%) (NPG: N-phenylglycine, 98% pure, Anaiji; IOD: When used in combination with diphenyl iodide hexafluorophosphate, 97% pure, Anagy), the acrylate double bond conversion rate can reach 90%. After adding additives, the acrylate double bond conversion rate was not greatly increased, but the polymerization rate was increased. Therefore, it shows that the developed single-component initiator preferentially absorbs intramolecular hydrogen for initiation during the hydrogen absorption process, and intermolecular Hydrogen absorption serves as a supplement to once again verify the effectiveness of single-component photoinitiation.

Existing non-patent literature (Recent advances on naphthalic anhydrides and 1,8-naphthalimide-based photoinitiators of polymerization, Guillaume Noirbent, Frédéric Dumur, European Polymer Journal, 132, 109702, 2020. (https://doi.org/10.1016/ j.eurpolymj.2020.109702.) The conversion rate of NAPHT-43/Iod (0.5%/2%, w/w) in Table 7 on page 18 under 405nm, 110Mw/ ^cm2 irradiation is only about 60%, as can be seen , the photoinitiator provided in the prior art has a large dosage, high optical density and low conversion rate, but the naphthalimide photoinitiator disclosed in this application has better initiating ability than the existing naphthalimide photoinitiator. , the naphthalimide photoinitiator disclosed in this application still has a high conversion rate at a lower dosage and lower optical density.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (10)

1. A class of naphthalimide photoinitiators, characterized in that its structure is shown in general formula I: In general formula I, The structure of R ₁ is shown in the general formula II. In the general formula II, the value of n is any positive integer; R ₂ is selected from Br; R ₃ is selected from substituents at an indefinite position on the benzene ring. 2. A type of naphthalimide photoinitiator according to claim 1, characterized in that R ₂ in the general formula I can also be selected from H, NH ₂ , substituted or unsubstituted phenyl, nitrogen One of propidine, azetidine, tetrahydropyrrole, morpholine, piperidine, hexamethyleneimine or dimethylamine; The substituent indicated in the substituted phenyl group is selected from the group consisting of H, OH, SH, NH ₂ , NO ₂ , CN, COOH, C _1-8 alkoxy, C _1-8 alkylamino, C _1-8 One of amide group, halogen or C _1-8 haloalkyl group. 3. A kind of naphthalimide photoinitiator according to claim 1, characterized in that the substituent at an indefinite position of the benzene ring is selected from the group consisting of H, OH, SH, NH ₂ , NO ₂ , CN, COOH , C _1-8 alkoxy group, C _1-8 alkylamino group, C _1-8 amide group, one of halogen or C _1-8 haloalkyl group; The value of n is 1, 2 or 3. 4. A photopolymerizable liquid composition containing the naphthalimide photoinitiator according to any one of claims 1 to 3, characterized in that the photopolymerizable liquid composition includes 0.01-0.1wt% naphthoyl Imine photoinitiator, the balance is tripropylene glycol diacrylate; Or it is composed of an amine compound, an onium salt compound and a naphthalimide photoinitiator, wherein the weight of the naphthalimide photoinitiator accounts for 0.1-5wt% of the photopolymerizable liquid composition, and the weight of the amine compound is naphthoyl 1-10 times the weight of the imine photoinitiator, and the balance is onium salt compounds. 5. The photopolymerizable liquid composition according to claim 4, wherein the amine compound is selected from the group consisting of L-phenylglycine, N-phenylglycine, 2-amino-2-phenylacetic acid, N -(2-Carboxy)phenylglycine, N-phenyl-N-methylglycine, ethyl 4-dimethylaminobenzoate, N,N-dimethylaniline, N-methyldiethanolamine, N-ethyl One or any combination of diethanolamine, triethanolamine, and triisopropanolamine. 6. The photopolymerizable liquid composition according to claim 4, wherein the onium salt compound is selected from the group consisting of iodonium salt compounds or sulfonium salt compounds. 7. The preparation method of the naphthalimide photoinitiator according to any one of claims 1-3, characterized in that it includes the following steps: React R ₃ -substituted 4-bromo-1,8-naphthalenedicarboxylic anhydride and R _1- substituted aniline in an organic solvent for 3-12 hours under an inert atmosphere at a reaction temperature of 120°C to obtain the target product; The process is as follows: 8. The preparation method of naphthalimide photoinitiator according to claim 7, characterized in that it also includes the following steps: Under an inert atmosphere, react the target product with compound R ₂ in a reaction solvent at a molar ratio of 1:1-1:1.5 for 3-12 hours at a reaction temperature of 125°C to obtain a photocatalyst containing naphthalimide derivatives. initiator; The process is as follows: 9. The preparation method of the naphthalimide photoinitiator according to claim 7 or 8, characterized in that the 4-bromo-1,8-naphthalenedicarboxylic anhydride containing R ₃ and the aniline containing R ₁ substitution The molar ratio is 1:1-4; The organic solvent is selected from at least one of absolute ethanol, acetic acid or formic acid; The reaction solvent is selected from dimethyl sulfoxide, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, acetonitrile, chlorobenzene, dichlorobenzene, anisole, and petroleum Ether, dioxane, tetrahydrofuran, pyridine, N,N-dimethylformamide, N-methylpyrrolidone, methyl tert-butyl ether, ethylene glycol dimethyl ether, acetone, methyl ethyl ketone, methanol, ethanol or At least one of propanol. 10. Application of the naphthalimide photoinitiator according to any one of claims 1 to 3 in the field of photocuring technology, characterized in that it is used in coatings, inks, 3D printing, and biomedicine.