Organic photochromic material, preparation method, high-precision photosensitive resin and preparation method thereof

Abstract

The invention relates to an organic photochromic material and a preparation method thereof as well as high-precision photosensitive resin and a preparation method thereof, the organic photochromic material is a yttrium-doped N-hydroxyethyl-3, 3-dimethyl-6-nitroindoline spiropyran complex, the organic photochromic material disclosed by the invention can quickly and sensitively generate color change under the stimulation of external light, and the high-precision photosensitive resin can be used for preparing the high-precision photosensitive resin. And the color contrast and reversibility are relatively high. The high-precision photosensitive resin prepared by combining the organic photochromic material and the photosensitive resin has better dispersity and stability, can avoid the problems of color fading, phase separation or performance degradation and the like in the use process of the material, and also can ensure that the original high mechanical strength, high resolution and fineness of the printing material are kept after the photosensitive resin is printed; and the reliability and durability of a printed product in practical application are ensured.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing materials, and in particular to organic photochromic materials, preparation methods, high-precision photosensitive resins and preparation methods thereof. Background Art

[0002] 3D printing technology has developed rapidly in recent years, among which stereolithography (SLA) technology has been widely used in many fields. SLA technology is a high-precision, high-resolution 3D printing technology that uses ultraviolet laser to cure photosensitive resin layer by layer to achieve the construction of three-dimensional structures. Traditional SLA materials mainly focus on mechanical properties and light curing speed, while functional SLA materials, such as photochromic materials and thermochromic materials, have gradually become research hotspots. Traditional SLA photosensitive resins have fixed colors after printing, which makes it difficult to meet the needs of some special application scenarios for color change functions. For example, in the field of decorative arts, different color effects need to be presented according to environmental changes, and in the field of smart sensors, color changes need to reflect changes in external physical or chemical parameters. The existing color-changing materials have poor compatibility with the SLA process, and there are problems such as unsatisfactory color change effects, low printing accuracy, and insufficient mechanical properties. Therefore, material preparation, performance improvement, and function increase are the focus of SLA technology development. For example, Chinese patent document CN 110437385 A discloses a photochromic material for 3D printing and a preparation method thereof, wherein the photochromic powder in the photochromic material is fused with a photosensitive resin to obtain a photosensitive resin. This solution has the following disadvantages: (1) the cost of purchased photochromic powder is relatively high and its competitiveness in the 3D printing business is not obvious; (2) the purchased photochromic powder contains impurities, and the photosensitive resin needs to be mixed before adding the photochromic powder separately. At the same time, the photosensitive resin will precipitate at the bottom of the resin tank during the printing process, resulting in sedimentation; therefore, the problems of existing photochromic powder include price problems, dissolution problems and sedimentation problems.

[0003] In summary, the existing technology needs to be improved. Summary of the invention

[0004] The present invention provides an organic photochromic material, a preparation method, a high-precision photosensitive resin and a preparation method thereof. The organic photochromic material of the present invention can change color quickly and sensitively under external light stimulation, and has high color contrast and reversibility. The high-precision photosensitive resin prepared by combining the organic photochromic material with the photosensitive resin has good dispersibility and stability, can avoid fading, phase separation or performance degradation of the material during use, and can also ensure that the original high mechanical strength, high resolution and fineness of the printed material are maintained after the photosensitive resin is printed, thereby ensuring the reliability and durability of the printed product in practical applications.

[0005] The present invention is achieved through the following technical solutions:

[0006] Solution 1)

[0007] An organic photochromic material, wherein the organic photochromic material is a yttrium-doped N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran complex, and the structural formula thereof is:

[0008]

[0009] Option 2)

[0010] A method for preparing an organic photochromic material comprises the following steps:

[0011] First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred to obtain a spiropyran solution;

[0012] Then, weigh YCl3·6H20 solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution;

[0013] Next, the spiropyran solution was added to the YCl3 aqueous solution; then the pH value of the solution was adjusted to 7-8;

[0014] Finally, the reaction is continued under stirring at room temperature for more than 2 hours, and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

[0015] Option 3)

[0016] A high-precision color-changeable photosensitive resin comprises the organic photochromic material.

[0017] Specifically, it includes the following components in parts by weight:

[0018] Acrylate monomer: 45-65 parts by weight;

[0019] 25 parts by weight of reactive diluent;

[0020] 5-10 parts by weight of the organic photochromic material;

[0021] 3-4 parts of photoinitiator;

[0022] Defoaming agent: 1 part.

[0023] Specifically, the acrylic acid ester monomer is one or any combination of two of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA) or diethoxybisphenol A dimethacrylate (2EO-BPADMA).

[0024] Specifically, the active diluent is one or any combination of two of hydroxyethyl acrylate (HEA), trimethylolpropane triacrylate (TMPTA) or tripropylene glycol diacrylate (TPGDA).

[0025] Specifically, the photoinitiator is 1-hydroxycyclohexyl phenyl ketone (photoinitiator 184), 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) or any combination of the two.

[0026] Specifically, the defoamer is BYK-306 from German BYK Chemical.

[0027] A method for preparing a high-precision color-changing photosensitive resin comprises the following steps: adding an acrylate monomer and an active diluent into a reaction container, stirring at room temperature for 20-30 minutes; subsequently adding the organic photochromic material, a photoinitiator and a defoamer under light-proof conditions, stirring and dispersing for 30-60 minutes; then fully dissolving at 60-80°C for 15-30 minutes; and finally filtering and degassing to obtain the high-precision color-changing photosensitive resin.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the organic photochromic material of the present invention can change color quickly and sensitively under external light stimulation, and has high color contrast and reversibility. The organic photochromic material is combined with a traditional photosensitive resin so that the material can change color quickly and sensitively under external stimulation, and has high color contrast and reversibility. Therefore, the product 3D printed with the photosensitive resin can undergo reversible color change under external light stimulation, thereby giving the material intelligent and controllable optical properties.

[0029] The dispersion and stability combined with photosensitive resin are better, avoiding problems such as fading, phase separation or performance degradation during the use of the material.

[0030] After printing, photosensitive resin maintains the original high mechanical strength, high resolution and fineness of the printed material, ensuring the reliability and durability of the printed products in practical applications.

[0031] The present invention combines the color-changing function with 3D printing technology, which can expand the application of 3D printing materials in the fields of smart sensors, wearable devices, adaptive optical devices, self-coloring decorative materials, etc. For example, by using the color-changing characteristics of the material, it is possible to develop smart sensors that can monitor environmental changes (such as temperature, humidity, light intensity, etc.) in real time, or to manufacture smart windows that can automatically adjust light transmittance according to ambient light.

[0032] The preparation method of the present invention is simple and controllable, improves material stability, promotes the development of 3D printing materials in the direction of intelligence and functionality, and expands its application prospects in the high-tech field. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments:

[0034] A method for preparing an organic photochromic material comprises the following steps:

[0035] First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred to obtain a spiropyran solution;

[0036] Then, weigh YCl3·6H20 solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution;

[0037] Next, the spiropyran solution was added to the YCl3 aqueous solution; then the pH value of the solution was adjusted to 7-8;

[0038] Finally, the reaction is continued under stirring at room temperature for more than 2 hours (preferably 2-4 hours), and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

[0039] In one embodiment, the mass concentration range of N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran in the ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is preferably 0.01 mol / L-0.1 mol / L.

[0040] In one embodiment, the mass concentration range of YCl3 in the YCl3 aqueous solution is preferably 0.001 mol / L-0.01 mol / L.

[0041] In one embodiment, the molar ratio of N-hydroxyethyl-3,3-dimethyl-6-nitroindolinol spiropyran to YCl3 is preferably in the range of 1-100:1.

[0042] When the concentration ratio range is between 1-100:1, the doping effect can be effectively controlled, while avoiding adverse phenomena such as agglomeration caused by excessive yttrium content; if the concentration ratio range is less than 1:1, it is generally not suitable for 3D printing and is only suitable for specific usage scenarios. For example, appropriately increasing the concentration ratio range in sensor materials can improve the heat resistance of the material.

[0043] When adding the spiropyran solution to the YCl3 aqueous solution, the speed should be slow and stirring should be continued during the addition.

[0044] When adjusting the pH value of the solution, use NaOH solution. The concentration of NaOH solution can be 1 mol / L.

[0045] The best standing time is more than 30 minutes. The precipitate can be filtered out using a vacuum filter. The precipitate can be washed with deionized water and anhydrous ethanol for more than 3 times to remove unreacted reagents and by-products. The washed precipitate can be placed in a vacuum drying oven and dried in an oven at 60°C for 12 hours.

[0046] The structural formula of the organic photochromic material obtained in the above embodiment is

[0047]

[0048] The yttrium ion (Y 3+ ) is doped by forming coordination bonds with oxygen or nitrogen atoms in spiropyran molecules; yttrium ions form coordination bonds with oxygen and nitrogen atoms in spiropyran molecules, restricting the rotation and vibration of spiropyran molecules, thereby improving the efficiency and stability of the photochromic reaction. At the same time, yttrium ions have a high coordination number and can form stable complexes with oxygen or nitrogen atoms in spiropyran molecules.

[0049] Under light, the spiropyran molecule undergoes a ring-opening reaction to form an open-ring form with a conjugated structure, resulting in a color change; under ultraviolet light, the closed-ring structure of the spiropyran undergoes isomerization and transforms into an open-ring anthocyanin structure, accompanied by a color change. This transformation is reversible. The doping of yttrium ions can also improve the thermal and chemical stability of the complex.

[0050] In one embodiment, the present invention also provides a high-precision color-variable photosensitive resin, comprising the following components in parts by weight:

[0051] Acrylate monomer: 45-65 parts by weight;

[0052] 25 parts by weight of reactive diluent;

[0053] 5-10 parts by weight of the organic photochromic material;

[0054] 3-4 parts of photoinitiator;

[0055] Defoaming agent: 1 part.

[0056] In one embodiment, the acrylic acid ester monomer is preferably one or any combination of two of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA) or diethoxybisphenol A dimethacrylate (2EO-BPADMA).

[0057] In one embodiment, the reactive diluent is preferably one or any combination of two of hydroxyethyl acrylate (HEA), trimethylolpropane triacrylate (TMPTA) or tripropylene glycol diacrylate (TPGDA).

[0058] In one embodiment, the photoinitiator is preferably 1-hydroxycyclohexyl phenyl ketone (photoinitiator 184), 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP), or any combination of both.

[0059] In one embodiment, the defoaming agent is preferably BYK-306 produced by BYK Chemical of Germany.

[0060] A method for preparing a high-precision color-changing photosensitive resin comprises the following steps: adding an acrylate monomer and an active diluent into a reaction container, stirring at room temperature for 20-30 minutes; subsequently adding the organic photochromic material, a photoinitiator and a defoamer under light-proof conditions, stirring and dispersing for 30-60 minutes; then fully dissolving at 60-80°C for 15-30 minutes; and finally filtering and degassing to obtain the high-precision color-changing photosensitive resin.

[0061] Stirring can be done by using a glass rod or other methods. After adding organic photochromic materials and other materials, first disperse at room temperature for a certain period of time until the solid particles are dispersed into the solution, then disperse at high temperature, and then continue to disperse at room temperature. After filtering, degassing is performed at a pressure of -0.08MPa for 10-20 minutes. The degassing time can be determined according to the situation.

[0062] In order to test the performance of the SLA 3D printed product using the photosensitive resin of the present invention, the prepared photosensitive resin was injected into the SLA 3D printer and printed using the following printing parameters:

[0063] 1. Laser wavelength: 355nm;

[0064] 2. Laser power: 50-200mW, preferably 100mW;

[0065] 3. Scanning speed: 1000-3000mm / s, preferably 2000mm / s;

[0066] 4. Layer thickness: 50-100, preferably 100 μm.

[0067] After printing, place the sample in an oven at 50-70°C for 1-3 hours to remove unreacted monomers. If needed, the sample can be ground and polished to obtain higher surface quality.

[0068] Example 1

[0069] Add the acrylate monomer and active diluent into the reaction container and stir at room temperature for 20 minutes; then add the organic photochromic material, photoinitiator and defoamer under light-proof conditions and stir and disperse for 30 minutes; then fully dissolve at 60°C for 30 minutes; finally filter and degas to obtain the high-precision color-changing photosensitive resin. The formula is shown in Table 1.

[0070] The method for preparing an organic photochromic material in this embodiment comprises the following steps:

[0071] First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred to obtain a spiropyran solution;

[0072] Then, weigh YCl3·6H20 solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution;

[0073] Next, the spiropyran solution was added to the YCl3 aqueous solution; then the pH value of the solution was adjusted to 7;

[0074] Finally, the reaction was continued under stirring at room temperature for 2 hours, and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

[0075] The mass concentration range of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran in the ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran is 0.1 mol / L.

[0076] The mass concentration range of YCl3 in YCl3 aqueous solution is 0.01 mol / L.

[0077] The molar ratio of N-hydroxyethyl-3,3-dimethyl-6-nitroindolyl spiropyran to YCl3 ranges from 100:1.

[0078] Example 2

[0079] Add the acrylate monomer and active diluent into the reaction container and stir at room temperature for 30 minutes; then add the organic photochromic material, photoinitiator and defoamer under light-proof conditions and stir and disperse for 60 minutes; then fully dissolve at 80°C for 15 minutes; finally filter and degas to obtain the high-precision color-changing photosensitive resin. The formula is shown in Table 1.

[0080] The method for preparing an organic photochromic material in this embodiment comprises the following steps:

[0081] First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred to obtain a spiropyran solution;

[0082] Then, weigh YCl3·6H20 solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution;

[0083] Next, the spiropyran solution was added to the YCl3 aqueous solution; then the pH value of the solution was adjusted to 7;

[0084] Finally, the reaction was continued under stirring at room temperature for 3 hours, and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

[0085] The mass concentration range of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran in the ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran is 0.05 mol / L.

[0086] The mass concentration range of YCl3 in YCl3 aqueous solution is 0.005 mol / L.

[0087] The molar ratio of N-hydroxyethyl-3,3-dimethyl-6-nitroindolyl spiropyran to YCl3 ranges from 50:1.

[0088] Example 3

[0089] Add the acrylate monomer and active diluent into the reaction container, stir at room temperature for 25 minutes; then add the organic photochromic material, photoinitiator, and defoamer under light-proof conditions, stir and disperse for 40 minutes; then fully dissolve at 70°C for 20 minutes; finally filter and degas to obtain the high-precision color-changing photosensitive resin. The formula is shown in Table 1.

[0090] The method for preparing an organic photochromic material in this embodiment comprises the following steps:

[0091] First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred to obtain a spiropyran solution;

[0092] Then, weigh YCl3·6H20 solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution;

[0093] Next, the spiropyran solution was added to the YCl3 aqueous solution; then the pH value of the solution was adjusted to 8;

[0094] Finally, the reaction was continued under stirring at room temperature for 4 hours, and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

[0095] The mass concentration range of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran in the ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran is 0.01 mol / L.

[0096] The mass concentration range of YCl3 in YCl3 aqueous solution is 0.001 mol / L.

[0097] The molar ratio of N-hydroxyethyl-3,3-dimethyl-6-nitroindolyl spiropyran to YCl3 is in the range of 1:1.

[0098] The photosensitive resins of Examples 4 and 5 adopt the organic photochromic material prepared in Example 1, and the formula is shown in Table 1.

[0099] Comparative Example 1

[0100] Add the acrylate monomer and active diluent into the reaction container and stir at room temperature for 20 minutes; then add the photoinitiator and defoamer under light-proof conditions, stir and disperse for 30 minutes; then fully dissolve at 60°C for 30 minutes; finally filter and degas, and obtain the high-precision color-variable photosensitive resin.

[0101] The samples prepared in the above three embodiments and comparative example 1 were subjected to performance tests including but not limited to the following:

[0102] Viscosity (NDJ-8S test); Flexural strength (ASTM D790 standard);

[0103] In the above embodiments and comparative examples,

[0104] The acrylic acid ester monomers used, methyl methacrylate and ethylene glycol dimethacrylate; and the reactive diluents, trimethylolpropane triacrylate (TMPTA) and tripropylene glycol diacrylate (TPGDA), are produced by Shandong Qiangsen Chemical Co., Ltd.

[0105] The N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran used was produced by Shanghai Kelaman Reagent Co., Ltd.

[0106] The photoinitiator 1-hydroxycyclohexyl phenyl ketone used was from Hubei Kewode Chemical Co., Ltd.

[0107] The defoaming agent used was produced by BYK Chemical Technology Consulting (Shanghai) Co., Ltd.

[0108] The amounts of the various components of the photosensitive resin used in Examples 1-5 and Comparative Examples are shown in Table 1.

[0109] Table 1. Dosage of each component of the photosensitive resin for 3D printing in each embodiment and comparative example

[0110]

[0111] Table 2. Mechanical properties and color changes of photosensitive resins for 3D printing in various embodiments and comparative examples

[0112]

[0113] As can be seen from Table 2, the 3D printing SLA color-changing photosensitive resin and the preparation method thereof of the present invention have the following significant advantages:

[0114] Excellent color-changing performance: By adding the organic photochromic agent of the present invention and effectively and evenly dispersing it, the photosensitive resin can achieve obvious and reversible color changes under different lighting conditions. For example, under the alternating irradiation of ultraviolet light and visible light, it can change from one color to another, and the color change is rapid and stable, which can be repeated many times, and can meet the needs of dynamic color changes in various application scenarios.

[0115] Good SLA printing adaptability: The reasonable combination of basic photosensitive resin monomers, active diluents and additives makes the resin have suitable viscosity, curing speed and molding performance, which can be smoothly printed in conventional SLA 3D printing equipment, and can accurately print 3D products with complex shapes, ensuring printing accuracy and surface quality, and overcoming the problem that traditional color-changing materials are difficult to mold in SLA printing.

[0116] The present invention is not limited to the above embodiments, and all improvements and substitutions made according to the principles of the present invention are within the protection scope of the present invention.

Claims

1. An organic photochromic material, characterized in that: The organic photochromic material is a yttrium-doped N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran complex, and its structural formula is:

2. The method for preparing an organic photochromic material according to claim 1, characterized in that: The steps include: First, N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran is dissolved in anhydrous ethanol and stirred evenly to obtain an ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindoline spiropyran; Then, weigh YCl3·6H2O solid, dissolve it in deionized water, and stir evenly to obtain YCl3 aqueous solution; Next, add the N-hydroxyethyl-3,3-dimethyl-6-nitroindole spiropyran ethanol solution to the YCl3 aqueous solution; then adjust the pH value of the solution to 7-8; Finally, the reaction is continued under stirring at room temperature for more than 2 hours, and then allowed to stand, filtered, and washed to obtain the organic photochromic material.

3. The method for preparing an organic photochromic material according to claim 1, characterized in that: The mass concentration range of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran in the ethanol solution of N-hydroxyethyl-3,3-dimethyl-6-nitroindolylspiropyran is 0.01 mol / L-0.1 mol / L.

4. The method for preparing an organic photochromic material according to claim 1, characterized in that: The mass concentration range of YCl3 in YCl3 aqueous solution is 0.001mol / L-0.01mol / L.

5. The method for preparing an organic photochromic material according to claim 1, characterized in that: The molar ratio of N-hydroxyethyl-3,3-dimethyl-6-nitroindolinol spiropyran to YCl3 ranges from 1 to 100:

1.

6. A high-precision color-changeable photosensitive resin, characterized in that: The invention comprises the organic photochromic material according to claim 1.

7. The high-precision color-variable photosensitive resin according to claim 6, characterized in that: It also includes acrylate monomer, reactive diluent, photoinitiator and defoamer, and the weight proportions of each component are as follows: Acrylate monomer 59-65 parts by weight; 25 parts by weight of reactive diluent; 5-10 parts by weight of the organic photochromic material according to claim 1; 3-4 parts of photoinitiator; 1 part defoamer.

8. The high-precision color-variable photosensitive resin according to claim 1, characterized in that: The acrylic acid ester monomer is one or any combination of two or more of methyl methacrylate, ethylene glycol dimethacrylate or diethoxybisphenol A dimethacrylate; the active diluent is one or any combination of two or more of hydroxyethyl acrylate, trimethylolpropane triacrylate or tripropylene glycol diacrylate.

9. The high-precision color-variable photosensitive resin according to claim 1, characterized in that: The photoinitiator is one or any combination of 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone; the defoamer is BYK-306 produced by German BYK Chemical.

10. A method for preparing a high-precision color-variable photosensitive resin according to any one of claims 7 to 9, characterized in that: The method comprises the following steps: adding acrylate monomer and active diluent into a reaction container, stirring for 20-30 minutes at room temperature; then adding the organic photochromic material, photoinitiator and defoamer into the reaction container under light-proof conditions, stirring and dispersing for 30-60 minutes; then fully dissolving at 60-80°C for 15-30 minutes; and finally filtering and degassing to obtain the high-precision color-variable photosensitive resin.

Images