Preparation method and application of low viscosity, low volatile hyperbranched epoxy resin

Abstract

The application discloses a preparation method and application of a low-viscosity, low-volatility hyperbranched epoxy resin, and the hyperbranched epoxy resin is a spherical molecule, has a hyperbranched structure, has few chain segment entanglements, low crystallinity, low viscosity and high solubility, and is easy to clean; the molecular main chain simultaneously contains benzene rings and flexible chain segment structures, and high strength is provided while good toughness is simultaneously provided; two ring-opening cyclic structures are contained on the terminal flexible chain, and the reaction activity is relatively high. The hyperbranched epoxy resin can replace the use proportion of a main high-viscosity epoxy resin in a traditional resin formula in a large proportion, is applied to 3D printing photocuring resin, and meets the demands of low viscosity, low volatilization, high toughness and high strength.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, specifically to a method for preparing and applying a low-viscosity, low-volatility hyperbranched epoxy resin. Background Technology

[0002] 3D printing, also known as additive manufacturing, is a technology that uses 3D digital models as a basis to create physical objects by adding materials layer by layer. SLA (Stereolithography) is a 3D printing technology that uses photosensitive resin as a raw material. This method offers fast printing speeds, high dimensional accuracy, and the ability to create complex shapes. It is a mature and widely used 3D printing technology, and was one of the first to achieve large-scale commercialization. While 3D printing was previously used primarily for manufacturing model products, it has now matured to the point where it can be directly used in the mass production of some products, and its application areas and scope are expanding year by year.

[0003] Traditional SLA photopolymer printing resins are mainly composed of reactive diluents, prepolymers, tougheners, photoinitiators, and other additives. Because the prepolymers and tougheners often have high viscosity, a large amount of diluent must be used in the formulation to reduce the system viscosity. Volatile small-molecule diluents not only pose potential threats to operators and the environment, but also cause optical path contamination and gradual thickening of the raw material solution. Optical path contamination (light scattering) increases the surface roughness of the parts, while resin thickening leads to reduced yield and severe surface delamination, limiting the long-term large-scale application prospects of SLA photopolymerization. Furthermore, photopolymer resins generally suffer from poor toughness. A common approach is to introduce flexible segments into the oligomers and tougheners to ensure flexibility, but this also leads to increased viscosity and reduced strength. Therefore, it is difficult for conventional photopolymer resins to simultaneously achieve a combination of low viscosity, low volatility, high toughness, and high strength.

[0004] Therefore, it is necessary to propose a method for preparing low-viscosity, low-volatility hyperbranched epoxy resin to meet the performance requirements for photopolymerizable 3D printing materials. Summary of the Invention

[0005] This invention provides a method for preparing a low-viscosity, low-volatility hyperbranched epoxy resin to meet the performance requirements of 3D printing photocurable resins, which combine low viscosity, low volatility, high toughness, and high strength.

[0006] In view of this, the solution of the present invention is as follows:

[0007] The first aspect of the present invention is to provide a low-viscosity, low-volatility hyperbranched epoxy resin having the structural formula shown in Formula I:

[0008]

[0009] Where R2 is ~~ represents the junction of functional groups;

[0010] R1 is

[0011] A second aspect of the present invention is to provide a method for preparing the hyperbranched epoxy resin described in the first aspect, comprising the following steps:

[0012] S1. Trimeric trioxide and diethylene glycol undergo hydrolysis and esterification at 110-120℃ to obtain intermediate one;

[0013] S2. Intermediate 1 reacts with trimellitic anhydride in the presence of dehydrating agent 1 and catalyst 1 to obtain intermediate 2;

[0014] S3. Intermediate 2 and Intermediate 3 undergo esterification reaction under the action of dehydrating agent 2 and catalyst 2 to obtain Intermediate 4; Intermediate 3 is obtained by hydrolysis and esterification reaction of 2,7-dioxane[4.4]nonane-1,3-dione and diethylene glycol at 110-120℃;

[0015] S4. Intermediate IV reacts with epichlorohydrin under the action of catalyst III, and then reacts with alkaline solution to obtain the hyperbranched epoxy resin shown in Formula I.

[0016] The structural formulas of intermediate one, intermediate two, intermediate three, and intermediate four are as follows:

[0017]

[0018]

[0019] Further, in step S1, the molar ratio of trimellitic anhydride to diethylene glycol is 1:1;

[0020] And / or, in step S2, the molar ratio of intermediate one to trimellitic anhydride is 3:1;

[0021] And / or, in step S3, the molar ratio of the 2,7-dioxane[4.4]nonane-1,3-dione to diethylene glycol is 1:1;

[0022] And / or, in step S3, the molar ratio of intermediate two to intermediate three is 1:6;

[0023] And / or, in step S4, the intermediate tetra and epichlorohydrin are in a molar ratio of 1:6;

[0024] And / or, in step S4, the base is an inorganic base with a molar ratio of 1:1 to epichlorohydrin.

[0025] Furthermore, the first and second dehydrating agents are xylene;

[0026] And / or, catalyst one and catalyst two are each independently selected from one of p-toluenesulfonic acid, thionyl chloride, and trifluoromethanesulfonic acid;

[0027] And / or, the catalyst tri is tetramethylammonium bromide.

[0028] Furthermore, in steps S1-S4, the solvent used in the preparation process of intermediate one, intermediate two, intermediate three or intermediate four is N,N-dimethylformamide.

[0029] Further, in step S4, the alkaline solution reaction is completed dropwise under reduced pressure within 1 hour, and then the reaction continues for another half hour. The generated salt solution is removed by filtration, the organic phase is washed with water until neutral, and finally epichlorohydrin is removed by reduced pressure distillation to obtain the hyperbranched epoxy resin liquid.

[0030] The third objective of this invention is to propose the application of the hyperbranched epoxy resin described in the first aspect or the hyperbranched epoxy resin prepared by the method described in the second aspect in photopolymerization 3D printing.

[0031] The fourth objective of this invention is to provide a low-viscosity, low-volatility photosensitive resin composition, comprising, by weight, 30-70 parts of hyperbranched epoxy resin; 5-20 parts of alicyclic epoxy resin; 5-20 parts of acrylate compound; 3-7 parts of photoinitiator; and 0.2-1 parts of additives; wherein the hyperbranched epoxy resin is the hyperbranched epoxy resin described in the first aspect or the hyperbranched epoxy resin obtained by the preparation method described in the second aspect.

[0032] Further, the alicyclic epoxy resin is selected from at least one of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, bis((3,4-epoxycyclohexyl)methyl) adipate, 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexane carboxylate), and 3,4-epoxycyclohexylmethyl methacrylate.

[0033] And / or, the acrylate compound is one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 3(2-hydroxyethyl) isocyanurate triacrylate, bis-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0034] And / or, the photoinitiator includes a free radical photopolymerization initiator and a cationic photopolymerization initiator;

[0035] And / or, the additives include leveling agents and defoamers.

[0036] Preferably, the free radical initiator is one or more of 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; the cationic initiator is one or more of triphenylthionium hexafluoroantimonate, diphenyl-(4-phenylthionium)phenylsulfonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, and diphenyliodonium hexafluoroarsenate.

[0037] A fifth objective of this invention is to provide a 3D printed article obtained by 3D printing and curing the resin composition described in the fourth aspect.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The hyperbranched epoxy resin of this invention has the following characteristics: (1) the spherical molecules have a hyperbranched structure, with less chain segment entanglement, low crystallinity, low viscosity and high solubility, and the product is easy to clean; (2) the molecular backbone contains both benzene rings and flexible chain segment structures, providing high strength while also having good toughness; (3) the terminal flexible chain contains two ring structures that can be opened, resulting in high reactivity. It can replace a large proportion of the main high-viscosity epoxy resin in traditional resin formulations, thereby reducing the viscosity of the photosensitive resin combination. The hyperbranched epoxy resin can be used as a 3D printing photocurable resin to meet the requirements of low viscosity, low volatility, high toughness and high strength. Attached Figure Description

[0040] Figure 1 The infrared spectrum of the hyperbranched epoxy resin prepared according to an embodiment of the present invention is shown. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described in conjunction with preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In one embodiment, a method for synthesizing hyperbranched epoxy resin is provided, the specific steps of which are as follows:

[0043] 1. Weigh a certain amount of trimellitic anhydride (TMA) and place it in a reactor. Weigh diethylene glycol (DEG) at a molar ratio of 1:1, and add N,N-dimethylformamide (DMF) as solvent. Start stirring until the TMA is completely dissolved. React at 115°C for 3 hours. After the reaction is complete, remove the solvent by vacuum distillation. Separate the crude product by precipitation with deionized water, and finally dry it under vacuum to obtain a pale white solid, which is denoted as intermediate one. The reaction process is as follows:

[0044]

[0045] 2. Intermediate 1 and trimellitic anhydride (TMA) were placed in a reactor at a molar ratio of 3:1, and N,N-dimethylformamide (DMF) was added as solvent. The mixture was heated and stirred until all substances dissolved. Then, xylene (a dehydrating agent) and p-toluenesulfonic acid (a catalyst) were added, and the mixture was refluxed under reduced pressure at 130°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the crude product. The crude product was then subjected to methanol / water precipitation, centrifugation, and vacuum drying to finally obtain intermediate 2. The reaction process is as follows:

[0046]

[0047] R1 is The same applies below;

[0048] 3. Weigh equal amounts of 2,7-dioxane[4.4]nonane-1,3-dione and diethylene glycol and place them in a reactor. Add N,N-dimethylformamide (DMF) solvent, stir until homogeneous, and react at 110°C for 3 hours. After the reaction is complete, remove the solvent by vacuum distillation, wash with water, and dry under vacuum to obtain liquid intermediate III. The reaction process is as follows:

[0049]

[0050] 4. Intermediate II and Intermediate III were placed in a reactor at a molar ratio of 1:6, and then DMF solvent, xylene dehydrating agent and a small amount of p-toluenesulfonic acid catalyst were added. The mixture was refluxed under reduced pressure at 130°C for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the crude product. The crude product was then subjected to methanol / water precipitation, centrifugation and vacuum drying to finally obtain liquid intermediate IV.

[0051]

[0052] 5. Intermediate tetramethylammonium bromide and epichlorohydrin were placed in a reactor at a molar ratio of 1:6. A small amount of tetramethylammonium bromide catalyst was added, and the mixture was reacted in a water bath at 65°C for 6 hours. After the reaction was completed, an equal amount of sodium hydroxide aqueous solution as epichlorohydrin was added. The sodium hydroxide aqueous solution was added dropwise over 1 hour under reduced pressure, and the reaction was continued for another half hour. The generated salt solution was removed by filtration, and the organic phase was washed with water until neutral. Finally, epichlorohydrin was removed by reduced pressure distillation to obtain the hyperbranched epoxy resin liquid. The reaction process is as follows:

[0053]

[0054] The hyperbranched epoxy resin prepared in the above embodiments has the following characteristics: (1) the spherical molecules have a hyperbranched structure, with less chain segment entanglement, low crystallinity, low viscosity and high solubility, and the product is easy to clean; (2) the molecular backbone contains both benzene rings and flexible chain segment structures, providing high strength while also having good toughness; (3) the flexible chain at the end contains two ring structures that can be opened, resulting in high reactivity. Therefore, it can be applied to 3D printing photocurable resins to meet the requirements of low viscosity, low volatility, high toughness and high strength.

[0055] The prepared hyperbranched epoxy resin was subjected to infrared spectroscopy, and its infrared spectrum is shown below. Figure 1 As shown. In the infrared spectrum, 1033 cm⁻¹ -1 An asymmetric stretching vibration peak of -COC- appears at 1103 cm⁻¹. -1 The peak of CO stretching vibration is located at 600-800 cm⁻¹. -1 The absence of characteristic C-Cl absorption peaks indicates that the terminal flexible chains of the prepared hyperbranched epoxy resin have undergone a well-complete epoxidation ring-closure reaction. (1244 cm⁻¹) -1 The peak represents the in-plane bending vibration of the hydroxyl group, at 1725 cm⁻¹. -1 The peak of the stretching vibration at C=O is 2929 cm⁻¹. -1 The stretching vibration peak of alkyl groups (-CH2- and -CH-) is 3416 cm⁻¹. -1 The peak represents the stretching vibration of -OH. Combining the above preparation steps and the infrared spectrum, the hyperbranched epoxy resin can be identified as having the structural formula shown in Formula I:

[0056]

[0057] Where R2 is ~~ represents the junction of functional groups;

[0058] R1 is

[0059] The viscosity of the prepared hyperbranched epoxy resin was tested according to ASTM D2196 standard. Different test parameters were selected according to the rotor, speed and viscosity reference table. The viscosity of the prepared hyperbranched epoxy resin was found to be 950 mPa·s.

[0060] In the preferred embodiment, the amount of solvent N,N-dimethylformamide added in steps 1 and 3 is not limited to a specific value, and is mainly used to adjust the viscosity of the system to facilitate the full reaction.

[0061] In a preferred embodiment, the mass of the catalyst p-toluenesulfonic acid added in steps 2 and 4 is 0.5% to 1% of the total mass of the reactants. The amounts of solvent N,N-dimethylformamide and dehydrating agent xylene added are not limited to specific values ​​and are mainly used to adjust the viscosity of the system to facilitate a full reaction.

[0062] In a preferred embodiment, the mass of the catalyst tetramethylammonium bromide added in step 5 is 0.5% of the total mass of the reactants.

[0063] In another embodiment, a method for preparing a low-viscosity, low-volatility photosensitive material composition is proposed, the method being as follows: 30-70 parts by weight of the hyperbranched epoxy resin shown in Formula I, 5-20 parts by weight of the alicyclic epoxy resin, 5-20 parts by weight of the acrylic compound, 1.5-3 parts by weight of the free radical initiator, 1.5-4 parts by weight of the cationic initiator, 0.1-0.5 parts by weight of the leveling agent, and 0.1-0.5 parts by weight of the defoamer are added to a mixer, mixed and stirred in the mixer, and after being evenly dispersed, allowed to stand naturally to defoam, thereby obtaining a low-viscosity, low-volatility photosensitive material composition that can meet the requirements of high toughness and high strength after 3D printing.

[0064] In a preferred embodiment, the alicyclic epoxy resin is one or a mixture of two or more of the following in any proportion: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylate), and 3,4-epoxycyclohexylmethyl methacrylate. The above-mentioned alicyclic epoxy resin monomers are well known to those skilled in the art and can be purchased from Daicel (Japan), Jiangsu Taiter, and Nantong Xinnaxi.

[0065] In a preferred embodiment, the acrylate compound is one or a mixture of two or more of the following in any proportion: ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 3(2-hydroxyethyl) isocyanurate triacrylate, bis-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. These photocurable acrylate monomers are well-known to those skilled in the art and can be purchased from Sartoma Chemical Company, Zinxin Chemical Company, Changxing Chemical, Kojin Chemical (Japan), and Miwon Chemical (Korea).

[0066] In a preferred embodiment, the photoinitiator is a free radical photopolymerization initiator and a cationic photopolymerization initiator. The free radical initiator is one or more of 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. The cationic initiator is one or more of triphenylthionium hexafluoroantimonate, diphenyl-(4-phenylthionium)phenylsulfonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, and diphenyliodonium hexafluoroarsenate.

[0067] In a preferred embodiment, the additives are leveling agents and defoamers, and the additives can be various commercially available additives, such as Evonik TEGO leveling agent, BYK leveling agent, TEGO defoamer, and BYK defoamer.

[0068] In a preferred embodiment, the mixing speed is 300-800 r / min, the mixing temperature is 20-50℃, and the mixing time is 30-60 minutes.

[0069] The following are preferred implementation examples. For reagents or instruments not specified in the examples, these can be purchased from the market as standard products. For items not specified with particular conditions, standard conditions or manufacturer-recommended conditions should be followed.

[0070] Example 1

[0071] 1) Preparation of hyperbranched epoxy resin

[0072] Weigh 576g of trimellitic anhydride (TMA) and place it in a reactor. Weigh 318g of diethylene glycol (DEG) at a molar ratio of 1:1, and then add 750g of N,N-dimethylformamide (DMF) solvent. Start stirring until the TMA is completely dissolved. React at 115℃ for 3 hours. After the reaction is completed, remove the solvent DMF by vacuum distillation. Separate the crude product by precipitation with deionized water at 50℃. Finally, dry under vacuum to obtain a light white solid, which is denoted as intermediate product 1.

[0073] 192g of trimellitic anhydride was weighed and placed in a reactor. 894g of intermediate product 1 was weighed at a molar ratio of 1:3. 1000g of solvent N,N-dimethylformamide (DMF) was added, and the mixture was heated and stirred until all substances dissolved. 200g of dehydrating agent xylene and 8.145g of catalyst p-toluenesulfonic acid were then added. The mixture was refluxed under reduced pressure at 130℃ for 3 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the crude product. The crude product was then subjected to methanol / water precipitation, centrifugation, and vacuum drying to finally obtain intermediate product 2.

[0074] Weigh 936g of 2,7-dioxane[4.4]nonane-1,3-dione and 636g of diethylene glycol and place them in a reactor. Then add 750g of solvent N,N-dimethylformamide (DMF), stir evenly, and react at 110℃ for 3 hours. After the reaction is completed, remove the solvent by vacuum distillation, wash with water, and dry under vacuum to obtain liquid intermediate product 3.

[0075] Weigh 525g of intermediate product 2 and 786g of intermediate product 3 in a molar ratio of 1:6 and place them in a reactor. Then add 1000g of solvent DMF, 200g of dehydrating agent xylene and 9.83g of catalyst p-toluenesulfonic acid. Reflux under reduced pressure at 130℃ for 3 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain the crude product. Then, after methanol / water precipitation, centrifugation and vacuum drying, liquid intermediate product 4 is finally obtained.

[0076] Weigh 1257g of intermediate product 4 and 277.5g of epichlorohydrin and place them in a reactor. Add 7.67g of tetramethylammonium bromide catalyst and react in a water bath at 65°C for 6 hours. After the reaction is complete, add 300g of 40% sodium hydroxide aqueous solution. Add the sodium hydroxide aqueous solution dropwise over 1 hour under reduced pressure and continue the reaction for another half hour. Filter to remove the generated salt solution, wash the organic phase with water until neutral, and finally remove epichlorohydrin by vacuum distillation to obtain the hyperbranched epoxy resin liquid.

[0077] 2) Preparation of 3D printing photosensitive resin composition

[0078] 30 parts by weight of hyperbranched epoxy resin, 20 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 1.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 1.5 parts by weight of triphenylthionium hexafluoroantimonate, 0.1 parts by weight of leveling agent BYK 333, and 0.1 parts by weight of defoamer BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to defoam, a low-viscosity, low-volatility photosensitive resin composition was obtained.

[0079] Example 2

[0080] 1) The preparation process of the hyperbranched epoxy resin is the same as in Example 1;

[0081] 2) Add 50 parts by weight of hyperbranched epoxy resin, 20 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of leveling agent BYK 333, and 0.2 parts by weight of defoamer BYK-024 to a stirrer, stir at 500 r / min for 30 min at 25°C, and let stand to defoam, to obtain a low-viscosity, low-volatility photosensitive resin composition.

[0082] Example 3

[0083] 1) The preparation process of the hyperbranched epoxy resin is the same as in Example 1;

[0084] 2) 70 parts by weight of hyperbranched epoxy resin, 15 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 3 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 4 parts by weight of triphenylthionium hexafluoroantimonate, 0.5 parts by weight of leveling agent BYK 333, and 0.5 parts by weight of defoamer BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to defoam, a low-viscosity, low-volatility photosensitive resin composition was obtained.

[0085] Example 4

[0086] 1) The preparation process of the hyperbranched epoxy resin is the same as in Example 1.

[0087] 2) Add 50 parts by weight of hyperbranched epoxy resin, 10 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 15 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of leveling agent BYK 333, and 0.2 parts by weight of defoamer BYK-024 to a stirrer, stir at 500 r / min for 30 min at 25°C, and let stand to defoam, to obtain a low-viscosity, low-volatility photosensitive resin composition.

[0088] Example 5

[0089] 1) The preparation process of the hyperbranched epoxy resin is the same as in Example 1.

[0090] 2) Add 30 parts by weight of hyperbranched epoxy resin, 5 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 5 parts by weight of ethoxylated trimethylolpropane triacrylate, 1.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 2.5 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of leveling agent BYK 333, and 0.2 parts by weight of defoamer BYK-024 to a stirrer, stir at 500 r / min for 30 min at 25°C, and let stand to defoam, to obtain a low-viscosity, low-volatility photosensitive resin composition.

[0091] Comparative Example 1

[0092] 50 parts by weight of bisphenol A type epoxy resin, 15 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 10 parts by weight of 3-ethyl-3-hydroxymethyloxetane, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of BYK 333, and 0.2 parts by weight of BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to defoam, a conventional photosensitive resin composition was obtained.

[0093] Comparative Example 2

[0094] 50 parts by weight of bisphenol A type epoxy resin, 20 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of BYK 333, and 0.2 parts by weight of BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to remove bubbles, a photosensitive resin composition was obtained.

[0095] Comparative Example 3

[0096] 50 parts by weight of bisphenol A type epoxy resin, 15 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 10 parts by weight of 3-ethyl-3-hydroxymethyloxetane, 5 parts by weight of polytetrahydrofuran ether glycol, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of BYK 333, and 0.2 parts by weight of BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to defoam, a toughened photosensitive resin composition was obtained.

[0097] Comparative Example 4

[0098] 50 parts by weight of dendritic epoxy resin CYE-001 (viscosity 11000-13000 mPa·s, purchased from Weihai Chenyuan Molecular New Materials Co., Ltd.), 15 parts by weight of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 10 parts by weight of 3-ethyl-3-hydroxymethyloxetane, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylthionium hexafluoroantimonate, 0.2 parts by weight of BYK 333, and 0.2 parts by weight of BYK-024 were added to a stirrer and stirred at 500 r / min for 30 min at 25°C. After standing to defoam, a photosensitive resin composition was obtained.

[0099] Experimental Example

[0100] The photosensitive resin compositions of Comparative Examples 1-4 and Examples 1-5 were introduced into the resin tank of an SLA-type 3D printing equipment. The sample preparation process parameters of the printing equipment were set to be consistent. Three sets of standard bending samples and three sets of standard impact samples were prepared for each type of printing. At the same time, the viscosity and volatility of each photosensitive resin composition were tested.

[0101] 1. Bending performance test

[0102] The prepared standard bending samples were cured by irradiation with a UV lamp of the same power for 30 minutes, and then left to stand at room temperature for 48 hours to ensure that the resin composition in the standard bending samples was completely cured. The flexural strength of each resin composition after curing was tested according to ASTM D790-10 standard. The test results are shown in Table 1.

[0103] 2. Impact performance test

[0104] The prepared standard impact specimens were cured by irradiation with a UV lamp of the same power for 30 minutes, and then left to stand at room temperature for 48 hours to ensure that the resin composition in the standard bending specimens was completely cured. The impact resistance of each resin composition after curing was tested according to ASTM D256-10 standard. The test results are shown in Table 1.

[0105] 3. Resin viscosity test

[0106] Tests were conducted according to ASTM D2196 standard. Different test parameters were selected according to the rotor, speed, and viscosity reference table, and viscosity values ​​for each photosensitive resin composition were collected. The test results are shown in Table 1.

[0107] 4. Resin volatility test

[0108] 100g of the photosensitive resin composition was taken from each of the same-sized disposable cups and placed open in ovens at 60℃ and 80℃. Weight data were collected after 3, 5, 7, 10, and 14 days. The test results are shown in Table 2.

[0109] Table 1: Performance of photosensitive resins in comparative examples and embodiments

[0110] Test Results Bending strength / MPa Flexural modulus / MPa Impact strength (J / m) Viscosity / mPa·s Test Standards ASTM D790 ASTM D790 ASTM D256 ASTM D2196 Comparative Example 1 55 1532 24 363 Comparative Example 2 52 1440 21 417 Comparative Example 3 44 1105 28 356 Comparative Example 4 60 1602 30 374 Example 1 66 1675 35 319 Example 2 71 1744 37 332 Example 3 82 1893 41 340 Example 4 74 1789 33 347 Example 5 78 1835 36 351

[0111] Table 2: Results of Volatility Tests of Photosensitive Resins in Comparative Examples and Examples

[0112]

[0113] As can be seen from Table 1, the viscosity of the photosensitive resins provided in Examples 1-5 is generally controlled below 350 mPa·s, and their flexural strength, flexural modulus, and impact strength properties are significantly superior. Table 2 also shows that the volatile content of the photosensitive resins is relatively low after adding hyperbranched epoxy resin as the main component. In contrast, data from Comparative Examples 1-3 show that conventional photosensitive resins require the addition of a diluent (3-ethyl-3-hydroxymethyloxetane) to achieve a lower overall resin viscosity, but this leads to higher volatile content. Furthermore, while traditional formulations can improve the impact toughness of the resin by adding toughening agents, this also reduces the resin strength. Data from Comparative Example 4 shows that dendritic epoxy resin can provide a good toughening effect, but its high viscosity also necessitates the use of a diluent to reduce the resin system viscosity.

[0114] As can be seen from the above conclusions, by introducing hyperbranched epoxy resin as the main resin in the photosensitive resin composition of the present invention, and by adjusting the remaining components, the viscosity and volatility of the resin system are significantly reduced compared to traditional resins. At the same time, the toughness and strength of the photosensitive resin composition of the present invention are also improved compared to traditional resins, indicating broad prospects for future commercialization.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-viscosity, low-volatility hyperbranched epoxy resin, characterized in that, It has the structural formula shown in Equation I: ； Where R2 is , ~~ represents the junction of functional groups; R1 is .

2. The method for preparing the hyperbranched epoxy resin according to claim 1, characterized in that, Includes the following steps: S1. Trimeric trioxide and diethylene glycol undergo hydrolysis and esterification at 110-120℃ to obtain intermediate one; S2. Intermediate 1 reacts with trimellitic anhydride in the presence of dehydrating agent 1 and catalyst 1 to obtain intermediate 2; S3. Intermediate 2 and Intermediate 3 undergo esterification reaction under the action of dehydrating agent 2 and catalyst 2 to obtain Intermediate 4; Intermediate 3 is obtained by hydrolysis and esterification reaction of 2,7-dioxane[4.4]nonane-1,3-dione and diethylene glycol at 110-120℃; S4. Intermediate IV reacts with epichlorohydrin under the action of catalyst III, and then reacts with alkaline solution to obtain the hyperbranched epoxy resin shown in Formula I. The structural formulas of intermediate one, intermediate two, intermediate three, and intermediate four are as follows: 、 、 、 。 3. The preparation method according to claim 2, characterized in that, In step S1, the molar ratio of trimellitic anhydride to diethylene glycol is 1:1; And / or, in step S2, the molar ratio of intermediate one to trimellitic anhydride is 3:1; And / or, in step S3, the molar ratio of the 2,7-dioxane[4.4]nonane-1,3-dione and diethylene glycol is 1:1; And / or, in step S3, the molar ratio of intermediate two to intermediate three is 1:6; And / or, in step S4, the intermediate tetra and epichlorohydrin are in a molar ratio of 1:6; And / or, in step S4, the base is an inorganic base with a molar ratio of 1:1 to epichlorohydrin.

4. The preparation method according to claim 2, characterized in that, The water-removing agent one and water-removing agent two are xylene; And / or, catalyst one and catalyst two are each independently selected from p-toluenesulfonic acid and trifluoromethanesulfonic acid; And / or, the catalyst tri is tetramethylammonium bromide.

5. The preparation method according to claim 2, characterized in that, In steps S1-S4, the solvent used in the preparation of intermediate one, intermediate two, intermediate three or intermediate four is N,N-dimethylformamide.

6. The preparation method according to claim 2, characterized in that, In step S4, the reaction conditions for adding the alkaline solution are as follows: the addition is completed within 1 hour under reduced pressure, followed by a further reaction for half an hour. The generated salt solution is then removed by filtration, the organic phase is washed with water until neutral, and finally, epichlorohydrin is removed by reduced pressure distillation to obtain the hyperbranched epoxy resin liquid.

7. The application of the hyperbranched epoxy resin of claim 1 or the hyperbranched epoxy resin obtained by any one of claims 2-6 in photopolymerization 3D printing.

8. A low-viscosity, low-volatility photosensitive resin composition, characterized in that, The components, by weight, include 30-70 parts of hyperbranched epoxy resin; 5-20 parts of alicyclic epoxy resin; 5-20 parts of acrylate compound; 3-7 parts of photoinitiator; and 0.2-1 parts of additives. The hyperbranched epoxy resin is the hyperbranched epoxy resin of claim 1 or the hyperbranched epoxy resin obtained by the preparation method of any one of claims 2-5.

9. The resin composition according to claim 8, characterized in that, The alicyclic epoxy resin is selected from at least one of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, bis((3,4-epoxycyclohexyl)methyl) adipate, 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexyl carboxylate), and 3,4-epoxycyclohexylmethyl methacrylate. And / or, the acrylate compound is one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, bis-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. And / or, the photoinitiator includes a free radical photopolymerization initiator and a cationic photopolymerization initiator; And / or, the additives include leveling agents and defoamers.

10. A 3D printed article obtained by 3D printing and curing the resin composition of claim 9.

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