CN116574073A - Low-migration polymerizable UV-LED photoinitiator and preparation method and application thereof - Google Patents

Abstract

The invention discloses a low-migration polymerizable UV-LED photoinitiator and its preparation method and application; the invention dissolves hydroxy-containing aldehyde derivatives and ketone derivatives in a solvent, and adds an alkaline catalyst solution dropwise, Stir the reaction to form a precipitate, and then separate and purify the precipitate into an intermediate product; dissolve the intermediate product in an organic solvent, add an acid-binding agent and mix well, add an organic solution of olefinic acid chloride compound dropwise to the mixed solution, stir and react, TLC Monitor the reaction until the reaction is complete; quench the reaction, extract and separate, and purify to obtain a low-migration polymerizable UV‑LED photoinitiator. The photoinitiator of the present invention is a low migration, high initiating efficiency, high solubility, polymerizable ultraviolet photoinitiator, used as an ultraviolet photoinitiator for UV-LED light-curing coatings, inks and adhesives, dental materials , can achieve deep curing, and has broad application prospects.

Description

A low-migration polymerizable UV-LED photoinitiator and its preparation method and application

technical field

The invention relates to the technical field of photopolymerization, in particular to a low-migration polymerizable UV-LED photoinitiator and a preparation method and application thereof.

Background technique

Photocuring can be divided into free radical type and cationic type. The essence of free radical photocuring is that the photoinitiator decomposes rapidly under light radiation to generate active free radicals, which trigger photocurable resins and reactive diluents with double bonds. chain reaction polymerization crosslinking. Among the many types of photoinitiators, hydroxyketone photoinitiators are the most widely used photoinitiators in the field of photopolymerization. They have high initiation efficiency, good thermal stability, no yellowing phenomenon, and stable storage.

Currently commercially available free radical type II photoinitiator ITX (thioxanthones), such as the product of my country's patent CN113861162A, is suitable for photocurable materials composed of unsaturated polyester and the like. Its advantage is that it has good miscibility with organic solvents. It is used for UV polymerization and curing of corresponding resins together with tertiary amine complexing agents. ITX can be used in colorless or colored systems, and is widely used in conventional UV coatings. However, when used in food packaging inks, cigarette pack inks, and dental materials, there are problems of high mobility and low initiation efficiency; With the continuous development of technology, the mobility of photo-curable coating initiators in countries around the world is constantly decreasing, which limits the scope of use of such UV-LED photo-initiators.

The low migration of photoinitiators determines whether they can be applied to UV light curing systems for food packaging, cigarette packs, and dental materials. Among them, Liu Shanshan et al. The article analyzed in depth that photoinitiators are an important part of UV-inks. Recent studies have found that after UV inks are cured, the residual photoinitiators can contaminate the packaging materials through chemical migration or physical contact under certain conditions. food, thereby causing potential harm to human health. Therefore, research on low-migration photoinitiators is the main development trend in the field of photocuring in the future.

Contents of the invention

In view of the deficiencies in the prior art, the object of the present invention is to overcome the problems of high mobility and low initiation efficiency of the photoinitiator in the coating, and provide a low-migration polymerizable UV-LED photoinitiator and its preparation method and application ; Low migration, high initiation efficiency, polymerizable UV-LED photoinitiator of the present invention is used for UV-LED light-cured coating, has advantages such as low mobility, high initiation rate, can polymerize, and synthetic method yield is high .

The photoinitiator with a polymerizable group in the invention can be used as an initiator to copolymerize with oligomers and reduce the mobility of the photoinitiator.

The ketene photoinitiator developed by the present invention can effectively solve the problems of mobility and initiation efficiency, improve the application range of the ketene photoinitiator, and have obvious advantages in environmental performance and economy.

In order to achieve the above object, the object of the present invention is achieved through the following technical solutions.

A preparation method of low-migration polymerizable UV-LED photoinitiator, comprising the following steps:

(1) Dissolving the hydroxy-containing aldehyde derivatives and ketone derivatives in a solvent, stirring and mixing evenly, adding the alkaline catalyst solution dropwise, stirring and reacting to form a precipitate, and then separating and purifying the precipitate to obtain an intermediate product;

(2) Dissolving the intermediate product in an organic solvent, adding an acid-binding agent and mixing evenly, adding an organic solution of olefinic acid chloride compound dropwise to the mixed solution, stirring and reacting, and monitoring the reaction by TLC until the reaction is complete; quenching the reaction, extracting and separating, Purified low-migration polymerizable UV-LED photoinitiator.

Preferably, the structural formula of the hydroxy-containing aldehyde derivatives is as follows:

Preferably, the structural formula of the ketone derivatives is as follows:

Preferably, the structural formula of the olefinic acid chloride compound is as follows:

Preferably, the molar ratio of hydroxy-containing aldehyde derivatives to ketone derivatives in step (1) is 2-3:1;

Further preferably, the molar ratio of the hydroxy-containing aldehyde derivatives to the ketone derivatives in step (1) is 2:1;

Preferably, the molar dosage of the basic catalyst in step (1) is 1-3:1 of the ketone derivatives;

Preferably, the molar volume ratio of the hydroxy-containing aldehyde derivatives to the solvent in step (1) is 1mmol:1-3ml;

Preferably, the solvent described in step (1) includes one or more of ethanol, water, and methanol;

Preferably, the stirring reaction time of step (1) is 4h-8h;

Preferably, the temperature of the stirring reaction described in step (1) is room temperature;

Preferably, the basic catalyst in step (1) includes one or more of sodium hydroxide and potassium hydroxide.

Preferably, the concentration of the alkaline catalyst solution in step (1) is 1-5 mmol/ml.

Preferably, the molar ratio of the intermediate product described in step (2) to the olefinic acid chloride compound is 1:2-3;

Preferably, the molar ratio of the alkene acid chloride compound and the acid-binding agent in step (2) is 1:1-2;

Further preferably, the molar ratio of the alkene acid chloride compound and the acid-binding agent in step (2) is 1:1;

Preferably, the molar volume ratio of the intermediate product in step (2) to the organic solvent is 1mmol:5-20ml.

Preferably, the solvent of the organic solution of the alkene acid chloride compound described in step (2) is one or both of dichloromethane and tetrahydrofuran;

Preferably, the ratio of the amount of the alkene chloride compound to the organic solution in the organic solution of the alkene chloride compound in step (2) is 1 mmol: 0.5-2 ml.

Further preferably, the ratio of the amount of the alkene chloride compound to the organic solution in the organic solution of the alkene chloride compound in step (2) is 1 mmol: 1 ml.

Preferably, the temperature for adding the olefinic acid chloride compound dropwise in step (2) is 0°C-10°C;

Preferably, the stirring reaction temperature in step (2) is 0°C-6°C;

Preferably, the stirring reaction time of step (2) is 1h-3h;

Preferably, the organic solvent in step (2) is one or both of dichloromethane and tetrahydrofuran, and the acid-binding agent is one or both of triethylamine and pyridine.

Preferably, the separation and purification in step (1) is to wash with absolute ethanol, centrifuge, and dry to obtain an intermediate product;

Further preferably, the number of washings with absolute ethanol in step (1) is ≥3 times; the drying in step (1) is vacuum drying, and the drying temperature is 40-60°C;

Preferably, the quenching reaction described in step (2) is to add an inorganic base to adjust the pH to 7-8;

Preferably, the extraction and separation described in step (2) is to add ethyl acetate for extraction and separation;

Preferably, the purification in step (2) is to wash with saturated brine, dry over anhydrous sodium sulfate, distill off the solvent under reduced pressure, use a mixture of petroleum ether and ethyl acetate as the mobile phase, and use 200-300 mesh silica gel as the stationary phase. Column chromatography yielded the final product.

Further preferably, the drying of anhydrous sodium sulfate described in step (2) is to add anhydrous sodium sulfate to the ethyl acetate containing the final product, mix and stir evenly, observe that sodium sulfate is a mobile powder, and then stand for 0.5- 1h;

Further preferably, the volume ratio of the mixture of petroleum ether and ethyl acetate in step (2) is 1-3:1.

More preferably, the volume ratio of the mixture of petroleum ether and ethyl acetate described in step (2) is 2:1.

A low-migration polymerizable UV-LED photoinitiator is prepared by the above-mentioned preparation method.

Preferably, the absorption wavelength of the low migration polymerizable UV-LED photoinitiator is 350-425nm.

Application of the above-mentioned low-migration polymerizable UV-LED photoinitiator in photocuring.

Compared with prior art, advantage and beneficial effect of the present invention:

(1) The photoinitiator of the present invention has the characteristics of low mobility, high initiation efficiency, and polymerizability. Aiming at the deficiencies of ketene photoinitiators in terms of mobility and initiation efficiency, a low migration, high initiation efficiency, and polymerizable The polymerized UV-LED photoinitiator used in UV-LED photocurable coatings has the advantages of low mobility and high initiation rate, which effectively fills the gap in the application of ketene photoinitiators in certain fields.

(2) The present invention modifies the molecular structure, and the initiator itself contains C=C, which belongs to the polymerizable enone UV-LED photoinitiator.

(3) The compound of the present invention is a low migration, high initiation efficiency, polymerizable UV-LED photoinitiator.

(4) The synthesis process of the compound of the present invention is simple and the yield is high.

Description of drawings

Fig. 1 is the mass spectrogram of photoinitiator in embodiment 2.

Fig. 2 is the NMR spectrum figure of photoinitiator in embodiment 2.

Fig. 3 is the carbon nuclear magnetic spectrogram of photoinitiator in embodiment 2.

Fig. 4 is the ultraviolet-visible spectrogram of photoinitiator in embodiment 2.

Fig. 5 is the C=C conversion rate graph of photoinitiator and competing product ITX among the embodiment 1-3.

Detailed ways

The present invention is specifically described below in conjunction with the examples, but the protection scope of the present invention is not limited to the following examples.

Room temperature among the present invention is 20-30 ℃;

The room temperature in the following examples specifically refers to 25°C.

Example 1

A preparation method of low-migration polymerizable UV-LED photoinitiator, comprising the following steps:

(1) Dissolve m-hydroxybenzaldehyde (20mmol) and acetone (10mmol) in ethanol (40ml), add 10ml of aqueous sodium hydroxide solution (2.5mmol/ml) dropwise to the reaction system, stir at room temperature for 4h, during the reaction A yellow precipitate appeared; the precipitate was washed three times with absolute ethanol, purified by centrifugation, and vacuum-dried to obtain an intermediate product with a yield of 79%.

(2) Dissolve the product from the previous step (10mmol) in dichloromethane (100ml), add acid-binding agent triethylamine (40mmol) and mix well, cool to 0°C in an ice bath, and then add dichloromethane-diluted acryloyl chloride dropwise ( 20mmol, the dilution ratio is 1mmol:1ml, acryloyl chloride/dichloromethane) solution, stirred and reacted at 0°C for 2h, and the reaction was completed by TCL monitoring.

(3) adding inorganic base to adjust the pH to 7-8, quenching the reaction; extracting with ethyl acetate, washing with saturated brine, drying over anhydrous sodium sulfate, distilling off the solvent under reduced pressure, and using petroleum ether and ethyl acetate mixture as The mobile phase was 200-300 mesh silica gel as the stationary phase, and the final product CPBA-1 was obtained by column chromatography with a yield of 68%.

Example 2

A preparation method of low-migration polymerizable UV-LED photoinitiator, comprising the following steps:

(1) Dissolve 5-hydroxymethylfurfural (20mmol) and acetone (10mmol) in ethanol (40ml), add 10ml aqueous sodium hydroxide solution (2.5mmol/ml) dropwise to the reaction system, stir at room temperature for 4h, A yellow precipitate appeared during the reaction; the precipitate was washed three times with absolute ethanol, purified by centrifugation, and vacuum-dried to obtain an intermediate product with a yield of 76%.

(2) Dissolve the product from the previous step (10mmol) in dichloromethane (100ml), add acid-binding agent triethylamine (40mmol) and mix well, cool to 0°C in an ice bath, and then add dichloromethane-diluted acryloyl chloride dropwise ( 20mmol, the dilution ratio is 1mmol:1ml, acryloyl chloride/dichloromethane) solution, stirred and reacted at 0°C for 2h, and the reaction was completed by TCL monitoring.

(3) adding inorganic base to adjust the pH to 7-8, quenching the reaction; extracting with ethyl acetate, washing with saturated brine, drying over anhydrous sodium sulfate, distilling off the solvent under reduced pressure, and using petroleum ether and ethyl acetate mixture as The mobile phase is 200-300 mesh silica gel as the stationary phase, and the final product CPBA-2 is obtained by column chromatography with a yield of 74.6%.

The synthetic route of present embodiment photoinitiator is as follows:

Fig. 1 is the mass spectrogram of photoinitiator in embodiment 2.

Fig. 2 is the NMR spectrum figure of photoinitiator in embodiment 2.

Fig. 3 is the carbon nuclear magnetic spectrogram of photoinitiator in embodiment 2.

Fig. 4 is the ultraviolet-visible spectrogram of photoinitiator in embodiment 2.

It can be seen from Fig. 1 that the molecular weight of the initiator of embodiment 2 meets the expected design; it can be seen from Fig. 2 that the hydrogen spectrum of the molecule of the initiator of embodiment 2 meets the quantity of hydrogen in different environments, and conforms to the molecular structure; it can be seen from Fig. 3 that the embodiment 2 The carbon spectrum of the initiator molecule conforms to the number of carbons in different environments and the molecular structure; it can be seen from Figure 4 that the effective UV-LED absorption of the photoinitiator in Example 2 is at 300-425nm.

Example 3

A preparation method of low-migration polymerizable UV-LED photoinitiator, comprising the following steps:

(1) Dissolve 5-methyl salicylaldehyde (20mmol) and acetone (10mmol) in ethanol (40ml), add 10ml aqueous sodium hydroxide solution (2.5mmol/ml) dropwise to the reaction system, stir at room temperature for 4h, A yellow precipitate appeared during the reaction; the precipitate was washed three times with absolute ethanol, purified by centrifugal separation, and dried in vacuum to obtain 81% of the intermediate product.

(2) Dissolve the product from the previous step (10mmol) in dichloromethane (100ml), add acid-binding agent triethylamine (40mmol) and mix well, cool to 0°C in an ice bath, and then add dichloromethane-diluted acryloyl chloride dropwise ( 20mmol, the dilution ratio is 1mmol:1ml, acryloyl chloride/dichloromethane) solution, stirred and reacted at 0°C for 2h, and the reaction was completed by TCL monitoring.

(3) adding inorganic base to adjust the pH to 7-8, quenching the reaction; extracting with ethyl acetate, washing with saturated brine, drying over anhydrous sodium sulfate, distilling off the solvent under reduced pressure, and using petroleum ether and ethyl acetate mixture as The mobile phase is 200-300 mesh silica gel as the stationary phase, and the final product CPBA-3 is obtained by column chromatography, and the final yield is 64.56%.

Example 4

(1) Migration test

The synthesized CPBAs series photoinitiator (1%), co-initiator (2wt% TEOA, 2wt% Iod) and TMPTA monomer (95%) were mixed and stirred evenly according to the mass ratio respectively, and the coating film was prepared after standing and cured . The cured coating film was crushed and placed in 10ml of acetonitrile solvent, soaked at room temperature in the dark for 48h. After filtering and washing, the solution is diluted to 50ml, and the absorbance of the photoinitiator maximum absorption peak is measured with a UV-visible spectrophotometer, and the mobility (table 1) of the photoinitiator is quantitatively calculated according to Lambert Beer's law, and the formula is as follows :

Migration ratio＝(A×M×V _solution )/(ε×b×m ₀ )

In the formula, A is the absorbance, M is the relative atomic mass of the photoinitiator, V _solution is the total volume of the solution, ε is the molar absorptivity coefficient of the photoinitiator in the solution, b is the optical path length, m ₀ is the added value in the cured film quality of the photoinitiator.

Table 1 Photoinitiator Mobility

Photoinitiator Mobility Competing ITX 14.6% Example 1 1.24% Example 2 0.24% Example 3 1.73%

As can be seen from Table 1, the mobilities of the photoinitiators in the examples of the present invention are lower than those of competing products ITX, and there are 3 reasons for the analysis:

1) The present invention introduces the -C=C- double bond in the molecule to provide multiple sites for the initiator to participate in the photopolymerization, so that the initiator part participates in the double bond polymerization reaction, and the reaction is cured in the paint film, reducing the amount of the initiator migration;

2) The molecular weight of photoinitiator of the present invention is greater than ITX, and the chance that molecule diffuses out from coating reduces, thereby reduces initiator mobility;

3) The influence of molecular structure and group, such as the photoinitiator molecular weight of embodiment 1, 2 is relatively smaller than embodiment 3, but mobility is lower than embodiment 3.

(2) Double bond conversion rate

A real-time infrared spectrometer is used to detect the photopolymerization performance of the synthesized photoinitiator in situ. The signal measured by infrared is an absorption signal. The test time is 300s, and the real-time infrared spectrum recording range is 4000-600cm-1. The light source for photopolymerization is an LED light source with an emission wavelength of 365nm (light intensity is 100mW/cm2). A homogeneous mixture composed of different formulations of the CPBAs series was prepared, and the mixture was uniformly coated on a polyvinyl chloride (PVC) film, and then covered with a layer of PVC film to prevent oxygen inhibition during the test. Infrared spectroscopy was used to measure the change of the sample as the illumination time increased, and the stretching vibration change of the double bond at 810cm-1 was measured, and the C=O bond at 1720cm-1 was used as the standard. The calculation method of carbon-carbon double bond conversion rate (Table 2) is as follows:

DC(%)＝[1-(A ₈₁₀ /A ₁₇₂₀ ) _t /(A ₈₁₀ /A ₁₇₂₀ ) ₀ ]×100％

In the formula, (A ₈₁₀ /A ₁₇₂₀ ) ₀ and (A ₈₁₀ /A ₁₇₂₀ ) _t are the peak area ratios of C=C and C=O bonds before curing and at curing time t, respectively.

Table 2 is the C=C conversion rate of photoinitiator and competing product ITX in embodiment 1-3

Photoinitiator C=C conversion rate Competing ITX 54.7% Example 1 52.3% Example 2 51.89% Example 3 52.98%

Fig. 5 is the C=C conversion rate graph of photoinitiator and competing product ITX among the embodiment 1-3.

As can be seen from Table 2 and Fig. 5: when the photoinitiator addition amount is 1wt% in the embodiment of the present invention, initiate monomer polymerization C=C conversion ratio is close to commercially available product ITX, and photoinitiation efficiency is higher, and the product of the present invention The source of raw materials used is wide and cheap, and the synthesis is simple, and the use of the photoinitiator of the invention can reduce the cost of formulation materials.

The above examples are only preferred implementations of the present invention, and are only used to explain the present invention, rather than limit the present invention. Changes, replacements, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention shall belong to the present invention. protection scope of the invention.

Claims (10)

1. A method for preparing a low migration polymerizable UV-LED photoinitiator, comprising the steps of:

(1) Dissolving a hydroxy aldehyde derivative and a ketone derivative in a solvent, dropwise adding an alkaline catalyst solution, stirring to react to generate a precipitate, and then separating and purifying the precipitate to obtain an intermediate product;

(2) Dissolving the intermediate product in an organic solvent, adding an acid binding agent, uniformly mixing, dropwise adding an organic solution of an olefin acyl chloride compound into the mixed solution, stirring for reaction, and monitoring the reaction by TLC until the reaction is complete; quenching reaction, extracting, separating and purifying to obtain the low-migration polymerizable UV-LED photoinitiator.

2. The method for preparing a low migration polymerizable UV-LED photoinitiator according to claim 1, wherein the hydroxy aldehyde derivative has the following structural formula:

the structural formula of the ketone derivative is as follows:

the structural formula of the olefin acyl chloride compound is as follows:

3. the method for preparing a low migration polymerizable UV-LED photoinitiator according to claim 1, wherein the molar ratio of the hydroxy-containing aldehyde derivative to the ketone derivative in step (1) is 2-3:1, the molar dosage of the basic catalyst is 1-3 of ketone derivatives: 1, the molar volume ratio of the hydroxy aldehyde derivative to the solvent is 1mmol to 1-3ml;

the solvent in the step (1) comprises one or more of ethanol, water and methanol; the stirring reaction time is 4-8 hours; the temperature of the stirring reaction is room temperature; the alkaline catalyst comprises one or more of sodium hydroxide and potassium hydroxide.

4. The method of preparing a low migration polymerizable UV-LED photoinitiator according to claim 1, wherein the molar ratio of the intermediate product of step (2) to the olefin acid chloride-based compound is 1:2-3; the mol ratio of the olefin acyl chloride compound to the acid binding agent is 1:1-2; the molar volume ratio of the intermediate product to the organic solvent is 1mmol:5-20ml.

5. The method for preparing a low migration polymerizable UV-LED photoinitiator according to claim 1, wherein the temperature of the dropwise addition of the olefin acid chloride compound in step (2) is 0 ℃ to 10 ℃; the temperature of the stirring reaction in the step (2) is 0-6 ℃, and the time of the stirring reaction in the step (2) is 1-3 h;

the organic solvent in the step (2) is one or two of dichloromethane and tetrahydrofuran, and the acid binding agent is one or two of triethylamine and pyridine.

6. The method for preparing a low migration UV-LED polymerizable photoinitiator according to claim 1, wherein the separation and purification in step (1) is performed by washing with absolute ethanol, centrifuging, and drying to obtain an intermediate product;

the quenching reaction in the step (2) is to add inorganic base to adjust the pH value to 7-8;

the extraction and separation in the step (2) is carried out by adding ethyl acetate;

and (3) the purification in the step (2) is to wash with saturated saline water, dry with anhydrous sodium sulfate, decompress and distill to remove the solvent, and column chromatography is carried out by taking petroleum ether and ethyl acetate mixture as mobile phase and 200-300 mesh silica gel as stationary phase to obtain the final product.

7. The method for preparing a low migration polymerizable UV-LED photoinitiator according to claim 6, wherein the number of times the absolute ethanol of step (1) is washed is not less than 3 times; the drying in the step (1) is vacuum drying, and the drying temperature is 40-60 ℃;

the anhydrous sodium sulfate is dried in the step (2), namely, the anhydrous sodium sulfate is added into ethyl acetate containing a final product, and the mixture is uniformly mixed and stirred, and after the sodium sulfate is observed to be flowing powder, the mixture is stood for 0.5 to 1h;

and (3) the volume ratio of the petroleum ether to the ethyl acetate in the step (2) is 1-3:1.

8. A low migration polymerizable UV-LED photoinitiator, characterized in that it is obtainable by the preparation method according to any one of claims 1-7.

9. The low migration-polymerizable UV-LED photoinitiator according to claim 8, wherein the low migration-polymerizable UV-LED photoinitiator has an absorption wavelength between 350 nm and 425nm.

10. Use of the low migration polymerizable UV-LED photoinitiator according to claim 8 or 9 in photo-curing.