Solution mask molecules, methods of making and using the same

Abstract

The present application relates to a kind of solution mask molecules and its preparation method and application, belong to the technical field of photo-curable material.The solution mask molecules disclosed in the present application is stable to natural light by itself molecular main skeleton, and has larger molar extinction coefficient in ultraviolet absorption band, can preferentially shield natural light, thereby protecting the activity of photoinitiator, and can solve the problem of natural light storage resistance;Under high-intensity curing light source, solution mask molecules occur photodimerization, so that molar extinction coefficient is reduced and photoinitiator is induced to absorb light to generate free radicals, and material is rapidly cured.The present application solves the problem that photo-curable material cannot be stored in natural light in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of photocurable materials technology, and relates to a solution mask molecule, its preparation method and application. Background Technology

[0002] Photocuring technology has advantages such as low cost, high efficiency, energy saving and environmental protection, which has led to the widespread application of photocurable materials in the fields of coatings, adhesives, inks, optoelectronic materials and other technologies.

[0003] Photocurable materials include photoinitiators, monomers, prepolymers, and other functional additives. Among them, photoinitiators can rapidly generate free radicals after exposure, initiating the polymerization of monomers and prepolymers to obtain a photocurable coating.

[0004] The rapid polymerization reaction initiated by photoinitiators after exposure gives photocurable materials the advantage of fast curing speed. However, this also leads to premature micro-crosslinking due to light leakage (natural light) caused by high photosensitivity. This not only reduces the shelf life of photocurable materials but also limits their application in precision processing. The effective shelf life of ordinary photocurable materials is as low as 1-2 months, while the effective shelf life of photocurable materials for precision processing such as photolithography and additive manufacturing is even less than 15 days. In the process of transferring photocurable materials to production, the short shelf life not only increases the transportation costs of the materials but also reduces the quality of the processed products.

[0005] Therefore, finding new photoinitiators to enable photocurable materials to withstand natural light storage is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] In view of this, one objective of the present invention is to provide a solution mask molecule; a second objective of the present invention is to provide a method for preparing a solution mask molecule; a third objective of the present invention is to provide an application of a solution mask molecule in the preparation of photocurable materials; and a fourth objective of the present invention is to provide a photocurable material.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] 1. A solution mask molecule, the structural formula of which is shown below: Where R1 is -CH2CH2-, R2 is -H or -CH3, R3 is -CH3 or -CH=CH2, and n = 1 to 22.

[0009] 2. The method for preparing the above-mentioned solution mask molecules, wherein the preparation method includes the following steps:

[0010] (1) Hydroxy acrylate and 4-dimethylaminopyridine were dissolved in a polar organic solvent and stirred under ice bath conditions to dissolve them. An ethanol solution of (E)-3-pyrrolic acrylic acid was added dropwise to carry out the reaction. After the reaction was completed, the solvent was removed and the pyrrolic-acyloxy acrylate was obtained by SiO2 column chromatography.

[0011] (2) The pyrrole-acyloxy acrylate, bromoalkane and alkali metal hydroxide prepared in step (1) are dissolved in a polar organic solvent and stirred at room temperature under nitrogen purging. After the reaction is completed, the mixture is washed and extracted to remove the solvent and purified by SiO2 column chromatography to obtain the solution mask molecules.

[0012] The structural formula of the hydroxy acrylate is as follows: The structural formula of the pyrrole-oxyacrylate is as follows: The structural formula of the brominated hydrocarbon is: Where n is n = 1 to 22.

[0013] Preferably, in step (1), the hydroxy acrylate includes at least one of hydroxyethyl acrylate or hydroxyethyl methacrylate, and the polar organic solvent is ethanol;

[0014] In step (2), the bromohydrocarbon includes at least one of bromoalkanes or bromoolefins.

[0015] Preferably, in step (1), the molar ratio of (E)-3-pyrrolic acid, 4-dimethylaminopyridine and hydroxy acrylate is 1:0.1:0.8 to 1.2;

[0016] In step (1), the reaction time is more than 2 hours, and the eluent used in the SiO2 column chromatography purification process is ethyl acetate, and the developing solvent is a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 2:1.

[0017] Preferably, in step (2), the molar ratio of the pyrrole-acyloxyacrylate, the brominated hydrocarbon, and the alkali metal hydroxide is 1:0.8 to 1.2:2, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, and the polar organic solvent is dimethyl sulfoxide.

[0018] In step (2), the reaction time is 2 or more, and the washing and extraction are specifically: first wash with water, then extract with ethyl acetate and then dry with anhydrous sodium sulfate. The eluent used in the SiO2 column chromatography purification process is ethyl acetate, and the developing solvent is a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 2:1.

[0019] 3. Application of the above-mentioned solution mask molecules in the preparation of photocurable materials.

[0020] 4. A photocurable material, comprising, by weight, the following components: 0.01-0.1 parts of the above-mentioned solution mask molecules, 1-3 parts of photoinitiator, 10-20 parts of diluent, and 80-90 parts of acrylate resin.

[0021] Preferably, the photoinitiator is an acetophenone-based near-ultraviolet photoinitiator, the diluent is selected from at least one of acrylates or methacrylates, and the acrylate resin is selected from at least one of epoxy acrylates, polyurethane acrylates, or polyether acrylates.

[0022] Preferably, the photoinitiator is an acetophenone-based near-ultraviolet photoinitiator, including at least one of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (Irgacure 369), 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone (Irgacure 379), or 4,4'-bis(dimethylamino)diphenyl(methyl) ketone (michaelii MK);

[0023] The diluent is at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, or hydroxyethyl methacrylate.

[0024] The acrylate resin is at least one of Ebecryl1290, EAM-5060W, or F127DA.

[0025] The beneficial effects of this invention are as follows: This invention discloses a solution mask molecule whose main framework is stable to natural light and has a large molar extinction coefficient, exhibiting a greater than 10 molar extinction coefficient compared to commercial acetophenone-based near-ultraviolet photoinitiators in the corresponding ultraviolet absorption band. 2 ~10 3 With a molar extinction coefficient on the order of magnitude, when introduced into photocurable materials, it can preferentially shield natural light, thereby protecting the activity of the photoinitiator and playing a role in resistance to natural light storage. Under high-intensity curing light sources, the solution mask molecules undergo photodimerization, which reduces the molar extinction coefficient and induces the photoinitiator to absorb light and generate free radicals, thus enabling the material to be cured rapidly.

[0026] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1 A comparison of the molar extinction coefficients of the solution mask molecule a prepared in Example 1 and the acetophenone-based near-ultraviolet photoinitiator (Irgacure369);

[0029] Figure 2 This is a schematic diagram showing the photodegradation of the solution mask molecules prepared in Examples 1 to 3 under natural light conditions for 0 hours and 7 days.

[0030] Figure 3 The solution mask molecules prepared in Examples 1 to 3 were tested under LED@365nm ultraviolet light (100mW / cm²). 2 Schematic diagrams of photodegradation after 0s and 30s;

[0031] Figure 4 This is a schematic diagram of the photocuring kinetics of the system formed by the solution mask molecules a, b, and c in the present invention, which are respectively mixed with Irgacure369, Irgacure379, and micritone MK in a 1:1 molar ratio, under natural light and LED@365nm ultraviolet light.

[0032] Figure 5 The NMR spectrum of the product formed by dimerization of solution mask molecule b prepared in Example 2;

[0033] Figure 6 This is a schematic diagram illustrating how the solution mask molecule b prepared in Example 2 protects the activity of the commercial photoinitiator.

[0034] Figure 7 The absorption spectra of the solution mask molecule b prepared in Example 2 at different times during the dimerization process are shown.

[0035] Figure 8 This is a schematic diagram of the solution mask molecules in Comparative Example 4 of this invention, which do not contain long alkyl chains, thus preventing photodimerization and resulting in trans→cis isomerization. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0037] The structures of the solution mask molecules involved in the following embodiments are as follows:

[0038]

[0039] The structures of various acetophenone-based near-ultraviolet photoinitiators are shown below:

[0040]

[0041] The following epoxy acrylates are EAM-5060W from Shenzhen Sabis Technology Co., Ltd.; polyurethane acrylates are Ebecryl1290 from Zhanxin; and polyether acrylates are F127DA from Shenzhen Huano Biotechnology Co., Ltd.

[0042] Example 1

[0043] A solution mask molecule a, the synthetic route of which is as follows:

[0044]

[0045] The specific preparation method is as follows:

[0046] (1) Hydroxyethyl acrylate (1.16 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol) and 40 mL of ethanol were mixed and placed in a 100 mL flask. The mixture was stirred under ice bath conditions, and an ethanol solution of (E)-3-pyrrolic acid (prepared as follows: (E)-3-pyrrolic acid (denoted as a-i) (1.37 g 10 mmol) was dissolved in 20 mL of ethanol and stirred until homogeneous) was added dropwise. The reaction was carried out, and the solvent was removed under vacuum after 1.5 h. The solution was purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 1.99 g of pale yellow liquid (denoted as a-ii) (yield 85%).

[0047] (2) The pale yellow liquid (a-ii) (1.99 g 8.5 mmol), 1-bromobutane (1.17 g 8.5 mmol) and NaOH (0.68 g 17 mmol) prepared above were dissolved in dimethyl sulfoxide (25 mL). The mixture was stirred at room temperature and under nitrogen purging for 4 h. After the reaction was completed, the mixture was washed twice with water (40 mL), extracted twice with ethyl acetate (40 mL), dried with anhydrous sodium sulfate, and the solvent was removed under vacuum. The mixture was purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 1.94 g of yellow liquid, which is the solution mask molecule a (yield 75%).

[0048] The NMR characterization results of the solution mask molecule a prepared above are as follows:

[0049] 1 H NMR (300MHz, DMSO-d) δ7.64(m,1H), δ6.51(m,1H), δ6.43(m,1H), δ6.39(m,1H), δ6.05(m,1H), δ5. 93(m,2H), δ5.80(m,1H), δ4.43(d,4H), δ3.85(m,2H), δ1.77(m,2H), δ1.33(m,2H), δ0.93(m,3H).

[0050] Example 2

[0051] A solution mask molecule b, the synthetic route of which is as follows:

[0052]

[0053] The specific preparation method is as follows:

[0054] (1) Hydroxyethyl acrylate (1.16 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol) and 40 mL of ethanol were mixed and placed in a 100 mL flask. After stirring under ice bath conditions, an ethanol solution of (E)-3-pyrrolic acid (denoted as a-i) was added dropwise (the solution was prepared as follows: (E)-3-pyrrolic acid (1.37 g 10 mmol) was dissolved in 20 mL of ethanol and mixed evenly). After reacting for 1.5 h, the solvent was removed under vacuum conditions, and the solution was purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 1.99 g of pale yellow liquid (denoted as a-ii) (yield 85%).

[0055] (2) The above pale yellow liquid (a-ii) (1.99 g 8.5 mmol) and K2CO3 (2.4 g 17 mmol) were dissolved in acetonitrile (30 mL). After reacting at room temperature for 2 h, 4-bromo-1-butene (1.15 g 8.5 mmol) was added and the reaction was continued for 2 h. The mixture was first extracted twice with ethyl acetate (40 mL), then dried with anhydrous sodium sulfate and the solvent was removed under vacuum. The mixture was then purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 1.80 g of pale yellow liquid, which is the solution mask molecule b (yield 70%).

[0056] The NMR characterization results of the solution mask molecule b prepared by the above method are as follows:

[0057] 1H NMR (300MHz, DMSO-d) δ7.64(d,1H), δ6.51(m,1H), δ6.43(m,1H), δ6.39(m,1H), δ6.05(m,1H), δ5.93(m,2 H), δ5.80(m,1H), δ5.70(m,1H), δ5.03(m,1H), δ4.97(m,1H), δ4.43(d,4H), δ3.89(m,2H), δ2.44(m,2H).

[0058] Example 3

[0059] A solution mask molecule c, the synthetic route of which is as follows:

[0060]

[0061] The specific preparation method is as follows:

[0062] (1) Hydroxyethyl methacrylate (1.3 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol) and 40 mL of ethanol were mixed and placed in a 100 mL flask. The mixture was stirred under ice bath conditions. An ethanol solution of (E)-3-pyrrolic acid (denoted as a-i) was added (the solution was prepared as follows: (E)-3-pyrrolic acid (1.37 g 10 mmol) was dissolved in 20 mL of ethanol and stirred until homogeneous). The mixture was reacted for 1.5 h. The solvent was removed under vacuum conditions and purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 2:1). The result was denoted as ci (yield 80%).

[0063] (2) The pale yellow liquid (ci) (1.99 g 8 mmol) and K2CO3 (2.26 g 16 mmol) prepared above were dissolved in acetonitrile (30 mL). After reacting at room temperature for 2 h, 4-bromo-1-butene (1.08 g 8 mmol) was added and the reaction was continued for 2 h. The mixture was first extracted twice with ethyl acetate (40 mL), dried with anhydrous sodium sulfate, and the solvent was removed under vacuum. The mixture was purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1). 2.28 g of pale yellow liquid was obtained, which is the solution mask molecule c (yield 90%).

[0064] The NMR characterization results of the solution mask molecule c prepared above are as follows:

[0065] 1H NMR(300MHz, DMSO-d)δ7.64(d,1H),δ6.51(m,1H),δ6.43(m,1H),δ6.39(m,1H),δ6.15(s,1H)δ5.93(m,2H),δ5.80(m,1 H), δ5.70(m,1H), δ5.03(m,1H), δ4.97(m,1H), δ4.97(m,1H), δ4.43(d,4H), δ3.89(m,2H), δ2.44(m,2H), δ1.93(s,1H).

[0066] Example 4

[0067] A photocurable material, by weight, comprises the following components: 0.1 parts of the solution mask molecule a prepared in Example 1, 1 part of photoinitiator (Irgacure 369), 10 parts of diluent (1,6-hexanediol diacrylate), and 90 parts of acrylate resin (Ebecryl 1290).

[0068] Fourier transform infrared spectroscopy characterization showed that the final double bond conversion rate of the photocurable material composed in Example 4 was almost 0 after 7 days of storage under natural light, and the change rate of absorbance value in the ultraviolet absorption spectrum was as low as 0.1%; while at a light intensity of 100 mW / cm², the conversion rate was even lower. 2 Under 365nm ultraviolet light irradiation, after undergoing the photodimerization induction period, the final double bond conversion rate approached 100%, exhibiting high initiation activity. The hardness of the photocurable material was characterized by Rockwell hardness testing, with a hardness of 60HR; the dynamic friction coefficient of the photocurable material on a polytetrafluoroethylene film was measured to be 0.35.

[0069] Example 5

[0070] A photocurable material, by weight, comprises the following components: 0.05 parts of the solution mask molecule b prepared in Example 2, 1 part of photoinitiator (Irgacure369), 20 parts of diluent (tripropylene glycol diacrylate), and 80 parts of acrylate resin (EAM-5060W).

[0071] Fourier transform infrared spectroscopy characterization showed that the final double bond conversion rate of the photocurable material composed in Example 5 was almost 0 after 7 days of storage under natural light, and the change rate of absorbance value in the ultraviolet absorption spectrum was as low as 0.1%; while at a light intensity of 100 mW / cm², the conversion rate was even lower. 2 Under 365nm ultraviolet light irradiation, after undergoing a photodimerization induction period, the final double bond conversion rate approached 100%, demonstrating high initiation activity. The hardness of the photocurable material was characterized by Rockwell hardness testing, with a hardness of 70HR; ​​the dynamic friction coefficient of the photocurable material on a polytetrafluoroethylene film was measured to be 0.36.

[0072] Example 6

[0073] A photocurable material, by weight, comprises the following components: 0.05 parts of the solution mask molecule c prepared in Example 3, 2 parts of photoinitiator (milchone MK), 20 parts of diluent (hydroxyethyl methacrylate), and 80 parts of acrylate resin (F127DA).

[0074] Fourier transform infrared spectroscopy characterization showed that the final double bond conversion rate of the photocurable material composed in Example 6 was almost 0 after 7 days of storage under natural light, and the change rate of absorbance value in the ultraviolet absorption spectrum was as low as 0.1%; while at a light intensity of 100 mW / cm², the conversion rate was even lower. 2 Under 365nm ultraviolet light irradiation from an LED, after a photodimerization induction period, the final double bond conversion rate approached 100%, exhibiting high initiation activity. The hardness of the photocurable material was characterized by Rockwell hardness testing, yielding a hardness of 65HR; the dynamic friction coefficient of the photocurable material on a polytetrafluoroethylene film was measured to be 0.34.

[0075] Comparative Example 1

[0076] A photocurable material, by weight, comprises the following components: 1 part photoinitiator (Irgacure 369), 10 parts diluent (1,6-hexanediol diacrylate), and 90 parts acrylate resin (Ebecryl 1290).

[0077] The difference between the comparative example and Example 4 is that no solution masking molecules were added. Fourier transform infrared spectroscopy characterized the photocurable material, showing a double bond conversion rate of 35% within 10 seconds under natural light and a 50% decrease in absorbance value under ultraviolet light; while at a light intensity of 100 mW / cm²... 2 Under 365nm ultraviolet light irradiation from an LED, the material reached a plateau within 20 seconds, with the final double bond conversion rate approaching 100%. The hardness of the photocurable material was characterized by Rockwell hardness testing, with a hardness of 40HR. The dynamic friction coefficient of the photocurable material in Comparative Example 1 on a polytetrafluoroethylene film was measured to be 0.05.

[0078] Comparative Example 2

[0079] A photocurable material, by weight, comprises the following components: 0.1 parts of solution mask molecule d, 1 part of photoinitiator (Irgacure 369), 10 parts of diluent (1,6-hexanediol diacrylate), and 90 parts of acrylate resin (Ebecryl 1290).

[0080] The synthetic route for the above solution mask molecules is as follows:

[0081]

[0082] The preparation is carried out according to the following method:

[0083] (1) Hydroxyethyl acrylate (1.16 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol) and 40 mL of ethanol were mixed and placed in a 100 mL flask. After stirring under ice bath conditions, an ethanol solution of pyrrole-3-carboxylic acid was added dropwise (the solution was prepared by dissolving pyrrole-3-carboxylic acid (1.11 g 10 mmol) in 20 mL of ethanol and mixing thoroughly). The reaction was carried out for 1.5 h. The solvent was removed under vacuum conditions, and the product was purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 1.88 g of the intermediate product 2-(acryloyloxy)1-pyrrole-2-carboxylic acid ethyl ester (yield 90%).

[0084] (2) The intermediate product 2-(acryloyloxy)-1-pyrrole-2-carboxylic acid ethyl ester (1.78 g 8.5 mmol) and K2CO3 (2.4 g 17 mmol) prepared above were dissolved in acetonitrile (30 mL). After reacting at room temperature for 2 h, 4-bromo-1-butene (1.15 g 8.5 mmol) was added and the reaction was continued for 2 h. The mixture was first extracted twice with ethyl acetate (40 mL), then dried with anhydrous sodium sulfate and the solvent was removed under vacuum. The mixture was then purified by SiO2 column chromatography (the eluent was ethyl acetate, and the developing solvent was a mixed solvent formed by mixing petroleum ether and ethyl acetate in a volume ratio of 2:1) to obtain 2.03 g of solution mask molecule d (yield 77%).

[0085] The chemical structure of the solution mask molecule d prepared above is as follows: The NMR characterization results are as follows:

[0086] 1 H NMR (300MHz, DMSO-d) δ6.75(m,1H), δ6.72(m,1H), δ6.43(m,1H), δ6.06(m,1H), δ5.80(m,1H)δ5. 70(m,1H), δ5.03(m,1H), δ4.97(m,1H), δ4.61(m,2H), δ4.53(m,2H), δ3.89(m,2H), δ2.44(m,2H).

[0087] The difference between Comparative Example 2 and Example 4 is that pyrrole-3-carboxylic acid was used instead of (E)-3-pyrrolic acid in the preparation of the solution mask molecule d. The double bonds that do not undergo photodimerization cause the solution mask molecule d to lose its "light shielding" → "light receiving" conversion function and result in a blue shift in molecular absorption. Fourier transform infrared spectroscopy characterization showed that the double bond conversion rate of this photocurable material reached 45% within 50 seconds under natural light, and the absorbance value of the ultraviolet absorption spectrum decreased by 60%. However, at a light intensity of 100 mW / cm², the double bond conversion rate reached 45%, and the absorbance value decreased by 60%.2 Under 365nm ultraviolet light irradiation from an LED, the final double bond conversion rate reached 100%. The hardness of the photocurable material was characterized by Rockwell hardness testing, and the hardness was 60HR; the dynamic friction coefficient of the photocurable material in Comparative Example 2 on a polytetrafluoroethylene film was measured to be 0.25.

[0088] Comparative Example 3

[0089] A photocurable material, by weight, comprises the following components: 0.1 parts of solution mask molecule e, 1 part of photoinitiator (Irgacure 369), 10 parts of diluent (1,6-hexanediol diacrylate), and 90 parts of acrylate resin (Ebecryl 1290).

[0090] The structural formula of the above solution mask molecule e is: Its synthetic route is as follows:

[0091] Specifically, it is prepared according to the following method:

[0092] (1) Hexanol (1.02 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol) and 40 mL of ethanol were mixed and placed in a 100 mL flask. After stirring under ice bath conditions, an ethanol solution of (E)-3-pyrrolic acid (prepared by dissolving (E)-3-pyrrolic acid (1.37 g 10 mmol) in 20 mL of ethanol and mixing well) was added dropwise. The reaction was carried out for 1.5 h. The solvent was removed under vacuum and purified by SiO2 column chromatography (eluting agent was ethyl acetate, petroleum ether: ethyl acetate = 2:1) to obtain 2 g of pale yellow liquid, which is 1-hexyl-2-pyrrolic-2-carboxylic acid (yield 87%).

[0093] (2) The 1-hexyl-2-pyrrole-2-carboxylic acid (1.85 g 8 mmol) and K2CO3 (2.26 g 16 mmol) prepared above were dissolved in acetonitrile (30 mL). After reacting at room temperature for 2 h, 4-bromo-1-butene (1.08 g 8 mmol) was added and the reaction was continued for 2 h. The mixture was first extracted twice with ethyl acetate (40 mL), then dried with anhydrous sodium sulfate and the solvent was removed under vacuum. The mixture was purified by SiO2 column chromatography (eluent: ethyl acetate, petroleum ether: ethyl acetate = 2:1) to obtain 2.43 g of pale yellow liquid, which is the solution mask molecule e (yield 85%).

[0094] The NMR characterization results of the solution mask molecule e prepared above are as follows:

[0095] 1H NMR (300MHz, DMSO-d) δ7.64(d,1H), δ7.43(d,1H), 6.75(m,1H), δ6.72(m,1H), δ6.06(m,1H), δ5.70(m,1H), δ5.03(m,1 H) δ4.97(m,1H), δ4.25(m,1H), δ3.89(m,2H), δ2.44(m,2H), δ1.75(m,2H), δ1.33(m,2H), δ1.29(m,4H), δ0.96(m,3H).

[0096] The difference between Comparative Example 3 and Example 4 is that the prepared solution mask molecule e does not contain polymerizable carbon-carbon double bonds. Fourier transform infrared spectroscopy characterization shows that the double bond conversion rate of this photocurable material is almost zero after 7 days of storage under natural light, and the change in absorbance value in the ultraviolet absorption spectrum is less than 0.1%; while at a light intensity of 100 mW / cm², the double bond conversion rate is significantly lower. 2 Under 365nm ultraviolet light irradiation from an LED, the double bond conversion rate reached 100% within 10 seconds. The hardness of the photocurable material was characterized by Rockwell hardness testing, and the hardness was 40HR. The dynamic friction coefficient of the photocurable material in Comparative Example 3 on a polytetrafluoroethylene film was measured to be 0.05.

[0097] Comparative Example 4

[0098] A photocurable material, by weight, comprises the following components: 0.1 parts of solution mask molecule f, 1 part of photoinitiator (Irgacure 369), 10 parts of diluent (1,6-hexanediol diacrylate), and 90 parts of acrylate resin (Ebecryl 1290).

[0099] The structural formula of the solution mask molecule f is as follows: The preparation is carried out according to the following method:

[0100] Hydroxyethyl acrylate (1.16 g 10 mmol), 4-dimethylaminopyridine (DMAP) (0.122 g 1 mmol), and 40 mL of ethanol were mixed and placed in a 100 mL flask. The mixture was stirred in an ice bath and then slowly fed with an ethanol solution of (E)-3-pyrrolic acid (prepared by dissolving (E)-3-pyrrolic acid (1.37 g 10 mmol) in 20 mL of ethanol and mixing thoroughly). The reaction was carried out for 1.5 h. The solvent was removed under vacuum and purified by SiO2 column chromatography (eluent: ethyl acetate, petroleum ether: ethyl acetate = 2:1) to obtain 1.99 g of solution mask molecule f (yield 85%).

[0101] The NMR characterization results of the solution mask molecule f prepared above are as follows:

[0102] 1H NMR (300MHz, DMSO-d) δ7.64(d,1H), δ6.61(m,1H), δ6.43(m,1H), δ6.13(m,2H), δ6.05(m,1H) δ5.80(m,1H), δ5.01(s,1H), δ4.43(d,4H).

[0103] The difference between Comparative Example 4 and Example 4 is that no alkyl chain was introduced into the prepared solution mask molecule via 1-bromobutane. In this case, the double bond that would normally undergo photodimerization, lacking a long alkyl chain with steric hindrance on the pyrrole ring, tends to undergo trans-cis isomerization and does not possess the "light shielding" to "light receiving" conversion function. Fourier transform infrared spectroscopy characterized the photocurable material in Comparative Example 5. Under natural light, the double bond conversion rate reached 30% within 20 seconds, and the ultraviolet absorption spectrum showed a redshift; while under light intensity of 100 mW / cm², the double bond conversion rate reached 30%, and the ultraviolet absorption spectrum showed a redshift. 2 Under 365nm ultraviolet light irradiation from an LED, the final double bond conversion rate reached 100%. The hardness of the photocurable material was characterized by Rockwell hardness testing, and the hardness was 40HR; the dynamic friction coefficient of the photocurable material in Comparative Example 4 on a polytetrafluoroethylene film was measured to be 0.05.

[0104] Comparative Example 5

[0105] A photocurable material, by weight, comprises the following components: 0.1 parts of the solution mask molecule a prepared in Example 1, 1 part of the photoinitiator (camphor quinone), 10 parts of the diluent (1,6-hexanediol diacrylate), and 90 parts of the acrylate resin (Ebecryl 1290).

[0106] The difference between Comparative Example 5 and Example 4 is that camphorquinone, a visible light initiator, was used instead of acetophenone-based photoinitiators (Irgacure 369). Because camphorquinone has a wider absorption profile than solution mask molecule a, solution mask molecule a cannot protect the activity of the camphorquinone photoinitiator. Fourier transform infrared spectroscopy characterization showed that the photocurable material in Comparative Example 5 exhibited a 70% double bond conversion rate and a 60% decrease in ultraviolet absorption spectrum within 30 seconds under natural light; however, under light intensity of 100 mW / cm², the double bond conversion rate was significantly lower. 2 Under 365nm ultraviolet light irradiation, the final double bond conversion rate was 100%; in Comparative Example 5, the dynamic friction coefficient of the photocurable material on the polytetrafluoroethylene film was measured to be 0.33.

[0107] Performance testing

[0108] Figure 1 This is a comparison of the molar extinction coefficients of the solution mask molecule a prepared in Example 1 and the acetophenone-based near-ultraviolet photoinitiator (Irgacure 369). From... Figure 1It can be seen that the main framework of the solution mask molecule a prepared in Example 1 of this invention is stable to natural light and has a large molar extinction coefficient. Since the solution mask molecules b and c prepared in Examples 2 and 3 respectively have similar main frameworks to solution mask molecule a in Example 1, they also have large molar extinction coefficients. Therefore, the solution mask molecules prepared in this invention exhibit a molar extinction coefficient greater than 10 compared to commercial acetophenone-based near-ultraviolet photoinitiators (Irgacure 369) in the ultraviolet absorption band. 2 ~10 3 With a molar extinction coefficient on the order of magnitude, its introduction into photocurable materials can preferentially shield natural light, thereby protecting the activity of photoinitiators and enabling them to withstand storage under natural light.

[0109] Figure 2 This is a schematic diagram showing the photodegradation of the solution mask molecules prepared in Examples 1 to 3 under natural light conditions for 0 hours and 7 days. Figure 3 The solution mask molecules prepared in Examples 1 to 3 were tested under LED@365nm ultraviolet light (100mW / cm²). 2 Schematic diagrams of photodegradation after 0s and 30s. From Figure 2 and Figure 3 It can be seen that the solution mask / acetophenone photoinitiator system can withstand storage under natural light, but degrades under high-intensity ultraviolet light, initiating the curing reaction. Compared with existing technologies that achieve both high photosensitivity and high lightfastness in photocurable materials by adding polymerization inhibitors and designing photoinitiators resistant to natural light, this invention uses solution mask molecules to enable photocurable materials to possess both high photosensitivity and high natural lightfastness. Firstly, it does not consume photoinitiators during storage; secondly, by shielding light, it fundamentally solves the defect of premature micro-crosslinking caused by light leakage in photocurable materials. Therefore, solution mask molecules have a significant advantage over polymerization inhibitors in solving the fundamental problem of the incompatibility between high photosensitivity and high lightfastness in photocurable materials.

[0110] Figure 4 This is a schematic diagram illustrating the photocuring kinetics of the system formed by the solution mask molecules a, b, and c in the present invention, respectively, with Irgacure369, Irgacure379, and micritan MK in a 1:1 molar ratio, under natural light and LED@365nm ultraviolet light. Figure 4It can be seen that the final double bond conversion rate of the solution mask / acetophenone photoinitiator system under natural light is almost 0; while the final double bond conversion rate under high-intensity ultraviolet light reaches 100%. This indicates that the solution mask molecules prepared by the method of the present invention, when compounded with commercial acetophenone-based near-ultraviolet photoinitiators in a certain proportion to form a photoinitiator system (such as the photocurable materials prepared in Examples 4 to 6), can achieve the ability of photocurable materials to be stored under natural light, while the photocurable materials can be cured under high-intensity light sources.

[0111] Figure 5 The image shows the NMR spectrum of the product formed after dimerization of the solution mask molecule b prepared in Example 2. Figure 5 It can be seen that the solution mask molecule b prepared in Example 2 can indeed form a dimer product after dimerization. Similarly, since the solution mask molecule disclosed in this invention is similar to solution mask molecule b, both containing carbon-carbon double bonds that can form dimer products, it indicates that the solution mask molecule disclosed in this invention can also form a dimer product after dimerization.

[0112] Figure 6 This is a schematic diagram showing how the solution mask molecule b prepared in Example 2 protects the activity of the photoinitiator.

[0113] Figure 7 The images show the absorption spectra of the solution-masked molecule b prepared in Example 2 at different times during the dimerization process. Figure 7 It can be seen that solution mask molecule b underwent a significant photodimerization reaction. Similarly, other solution mask molecules disclosed in this invention also underwent significant photodimerization reactions. The reason why the solution mask molecules disclosed in this invention exhibit different absorption spectra at different times during the dimerization process is that: the solution mask molecules disclosed in this invention contain long alkyl chains. The steric hindrance effect of the long alkyl chains can suppress the trans-cis isomerism phenomenon of redshift in the absorption spectrum of the solution mask molecules, promote their photodimerization reaction, and improve the sensitivity of the "light shielding" to "light receiving" change; in addition, after the long alkyl chains are introduced into the polymer chain, they can increase the self-lubricating properties of the polymer and increase the compatibility between the solution mask molecules and the photocurable components, which is beneficial to the formulation of photocurable products.

[0114] Figure 8 The images show the absorption spectra of the solution-masked molecule f at different times during the dimerization process in Comparative Example 4. Figure 8 It can be seen that the solution mask molecules underwent a significant trans-cis isomerization reaction, rather than a photodimerization reaction. The reason for this is that the double bond of the solution mask molecule f, which would normally undergo photodimerization, lacks a long alkyl chain with steric hindrance on the pyrrole ring, and therefore tends to undergo trans-cis isomerization, thus lacking the "light shielding" to "light receiving" conversion function.

[0115] Therefore, when cured by a high-intensity light source, the solution mask molecules disclosed in this invention undergo photodimerization, and the reaction formula for the photodimerization reaction is as follows:

[0116] Wherein R1 is -CH2CH2-, R2 is -H or -CH3, R3 is -CH3 or -CH=CH2, and n = 1 to 22. After the solution mask molecules disclosed in this invention undergo photodimerization, their molar extinction coefficient near the 365nm absorption band decreases to close to 0. At this time, the solution mask molecules change from a light-shielding state to a light-receiving state, inducing the photoinitiator to absorb light and generate free radicals, thereby solidifying the material.

[0117] The solution mask molecules disclosed in this invention regulate the molar extinction coefficient of the solution mask molecules through photodimerization, thereby producing a "light shielding" → "light receiving" effect on commercial acetophenone-based near-ultraviolet photoinitiators. This protects the activity of commercial near-ultraviolet photoinitiators. When introduced into photocurable materials, photocurable materials containing the photoinitiator system can withstand natural light during storage and can be activated and cured during curing. This overcomes the fundamental problem that high photosensitivity and high resistance to natural light are mutually exclusive in photocurable materials. It improves the resistance to natural light while ensuring high photosensitivity, enabling photocurable materials to withstand natural light storage, which helps to extend the storage period of photocurable materials and expand their application range.

[0118] Meanwhile, the solution mask molecule disclosed in this invention contains polymerizable groups, which can introduce photodimer groups into the polymer chain during the photocuring process, increase the polymer crosslinking density, improve the material molding accuracy, and prevent the migration of solution mask molecules. This avoids unnecessary problems caused by the presence of solution mask molecules in the application of solution mask / commercial photoinitiator systems in food packaging and other applications.

[0119] A comparison of the performance of the photocurable materials prepared in Examples 4-6 and the photocurable materials in Comparative Examples 1-5 shows that the photocurable materials formed by adding the solution mask molecules disclosed in this invention exhibit significant improvements in natural light performance, crosslinking density, hardness, dynamic friction factor, and self-lubrication. For example, the photocurable materials containing solution mask molecules a, b, and c disclosed in this invention prepared in Examples 4-6 have superior natural light resistance compared to the photocurable materials without solution mask molecules prepared in Comparative Example 1; they have superior natural light resistance compared to the photocurable materials containing solution mask molecules d prepared in Comparative Example 2; they have higher crosslinking density and hardness compared to the photocurable materials containing solution mask molecules e prepared in Comparative Example 3; they have higher dynamic friction factor and self-lubrication compared to the photocurable materials containing solution mask molecules f prepared in Comparative Example 4; and they have superior natural light resistance compared to the camphor quinone-based photocurable materials in Comparative Example 5.

[0120] In summary, this invention discloses a solution mask molecule whose main framework is stable to natural light and has a large molar extinction coefficient. Compared to commercial acetophenone-based near-ultraviolet photoinitiators, this molecule exhibits a molar extinction coefficient greater than 10 in the corresponding ultraviolet absorption band. 2 ~10 3 With a molar extinction coefficient on the order of magnitude, when introduced into photocurable materials, it can preferentially shield natural light, thereby protecting the activity of the photoinitiator and playing a role in resistance to natural light storage. Under high-intensity curing light sources, the solution mask molecules undergo photodimerization, which reduces the molar extinction coefficient and induces the photoinitiator to absorb light and generate free radicals, thus enabling the material to be cured rapidly.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A solution mask molecule, characterized in that, The structural formula of the solution mask molecule is shown below: The specific structure is as follows: 。 2. The method for preparing the solution mask molecules according to claim 1, characterized in that, The preparation method includes the following steps: (1) Hydroxy acrylate and 4-dimethylaminopyridine were dissolved in a polar organic solvent and stirred under ice bath conditions to dissolve them. An ethanol solution of (E)-3-pyrrolic acid was added dropwise to carry out the reaction. After the reaction was completed, the solvent was removed and the pyrrolic-acyloxy acrylate was obtained by SiO2 column chromatography. (2) The pyrrole-acyloxy acrylate, bromoalkane and alkali metal hydroxide prepared in step (1) are dissolved in a polar organic solvent and stirred at room temperature under nitrogen purging. After the reaction is completed, the solvent is removed by washing and extraction, and the solution mask molecules are purified by SiO2 column chromatography. The structural formula of the hydroxy acrylate is as follows: The structural formula of the pyrrole-oxyacrylate is as follows: The structural formula of the bromohydrocarbon is as follows: .

3. The preparation method according to claim 2, characterized in that, In step (1), the hydroxy acrylate includes at least one of hydroxyethyl acrylate or hydroxyethyl methacrylate, and the polar organic solvent is ethanol; In step (2), the bromohydrocarbon includes at least one of bromoalkanes or bromoolefins.

4. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of (E)-3-pyrrolic acid, 4-dimethylaminopyridine and hydroxy acrylate is 1:0.1:0.8~1.2; In step (1), the reaction time is more than 2 hours, and the eluent used in the SiO2 column chromatography purification process is ethyl acetate, and the developing solvent is a mixed solvent formed by petroleum ether and ethyl acetate in a volume ratio of 2:

1.

5. The preparation method according to claim 2, characterized in that, In step (2), the molar ratio of the pyrrole-oxyacrylate, the brominated hydrocarbon and the alkali metal hydroxide is 1:0.8~1.2:2, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide, and the polar organic solvent is dimethyl sulfoxide; In step (2), the reaction time is more than 2 hours. The washing and extraction process is as follows: first wash with water, then extract with ethyl acetate, and then dry with anhydrous sodium sulfate. The eluent used in the SiO2 column chromatography purification process is ethyl acetate, and the developing solvent is a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 2:

1.

6. The application of the solution mask molecule of claim 1 in the preparation of photocurable materials.

7. A photocurable material, characterized in that, The composition of the photocurable material by weight is as follows: 0.01 to 0.1 parts of the solution mask molecule of claim 1, 1 to 3 parts of photoinitiator, 10 to 20 parts of diluent, and 80 to 90 parts of acrylate resin.

8. The photocurable material according to claim 7, characterized in that, The photoinitiator is an acetophenone-based near-ultraviolet photoinitiator, the diluent is selected from at least one of acrylate or methacrylate, and the acrylate resin is selected from at least one of epoxy acrylate, polyurethane acrylate, or polyether acrylate.

9. The photocurable material according to claim 8, characterized in that, The photoinitiator is an acetophenone-based near-ultraviolet photoinitiator, including at least one of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, or 4,4'-bis(dimethylamino)benzyl(methyl)one; The diluent is at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, or hydroxyethyl methacrylate. The acrylate resin is at least one of Ebecryl1290, EAM-5060W, or F127DA.

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