Preparation method and application of low-viscosity and low-volatility hyperbranched epoxy resin

Abstract

The invention discloses a preparation method and application of low-viscosity and low-volatility hyperbranched epoxy resin. The hyperbranched epoxy resin is a spherical molecule, has a hyperbranched structure, and is low in chain segment entanglement, low in crystallinity, low in viscosity, high in solubility and easy to clean. A molecular main chain simultaneously contains a benzene ring and a flexible chain segment structure, so that high strength and good toughness are provided; a flexible chain at the tail end contains two ring-opening ring structures, so that the reaction activity is relatively high. The hyperbranched epoxy resin can replace the use proportion of main body high-viscosity epoxy resin in a traditional resin formula in a large proportion, and the hyperbranched epoxy resin is applied to 3D printing light-cured resin to meet the requirements of low viscosity, low volatilization, high toughness and high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a preparation method and application of a low-viscosity and low-volatile hyperbranched epoxy resin. Background Art

[0002] 3D printing technology, also known as additive manufacturing technology, is a technology that uses 3D digital models as the basis to create entities by accumulating materials layer by layer. SLA light curing is a 3D printing technology that uses photosensitive resin as raw material. This method has a fast molding speed, high dimensional accuracy of the product, and can form more complex shapes. It has a mature process and is widely used. It is the first 3D printing technology to achieve large-scale commercial use. In the past, 3D printing technology was often used to manufacture model products. Now it has matured to the point where it can be directly used in mass production of some products, and its application areas and scope are expanding year by year.

[0003] The photosensitive resin used in traditional SLA photocuring printing is mainly composed of reactive diluents, prepolymers, tougheners, photoinitiators and other additives. Since the viscosity of prepolymers and tougheners is often high, a large amount of diluents must be used in the formula to reduce the viscosity of the system. Volatile small molecule diluents not only pose a potential threat to operators and the environment, but also cause equipment light path pollution and gradual thickening of the raw material liquid. Light path pollution (light scattering) will cause the surface roughness of the product to increase, and resin thickening will lead to problems such as reduced part yield and severe surface layering of the product. These problems limit the long-term large-scale application prospects of SLA photocuring. At the same time, photocurable resins generally have the problem of poor toughness. The usual practice is to introduce flexible segments into oligomers and tougheners to ensure their flexibility, but this will also lead to problems of increased viscosity and reduced strength. Therefore, it is difficult for conventional photocurable resins to simultaneously achieve a combination of low viscosity, low volatility, high toughness and high strength.

[0004] Therefore, it is necessary to propose a preparation method of a low-viscosity, low-volatile hyperbranched epoxy resin to meet the performance requirements of photocurable 3D printing materials. Summary of the invention

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

[0006] In view of this, the scheme of the present invention is:

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

[0008]

[0009] Among them, R2 is ~~ is the group connection point;

[0010] R1 is

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

[0012] S1. trimellitic anhydride and diethylene glycol undergo hydrolysis and esterification reaction at 110-120°C to obtain intermediate 1;

[0013] S2. Intermediate 1 undergoes an esterification reaction with trimellitic anhydride in the presence of a water-carrying agent 1 and a catalyst 1 to obtain intermediate 2;

[0014] S3. Intermediate 2 and intermediate 3 undergo esterification reaction in the presence of water-carrying agent 2 and catalyst 2 to obtain intermediate 4; intermediate 3 is obtained by hydrolysis and esterification reaction of 2,7-dioxaspiro[4.4]nonane-1,3-dione and diethylene glycol at 110-120°C;

[0015] S4. The intermediate four reacts with epichlorohydrin in the presence of a catalyst three to undergo an esterification reaction, followed by dropwise addition of an alkaline solution to obtain a hyperbranched epoxy resin of formula I;

[0016] The structural formulas of the intermediate 1, intermediate 2, intermediate 3 and intermediate 4 are respectively:

[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 the intermediate 1 to trimellitic anhydride is 3:1;

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

[0022] And / or, in step S3, the molar ratio of the intermediate 2 to the intermediate 3 is 1:6;

[0023] And / or, in step S4, the molar ratio of the intermediate four to epichlorohydrin is 1:6;

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

[0025] Furthermore, the water-carrying agent 1 and the water-carrying agent 2 are xylene;

[0026] And / or, the catalyst 1 and the catalyst 2 are each independently selected from one of p-toluenesulfonic acid, thionyl chloride and trifluoromethanesulfonic acid;

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

[0028] Furthermore, in steps S1-S4, the solvent used in the preparation process of intermediate 1, intermediate 2, intermediate 3 or intermediate 4 is N,N-dimethylformamide.

[0029] Furthermore, in step S4, the alkaline solution reaction dropwise addition reaction process is completed within 1 hour under reduced pressure, and the reaction is continued for half an hour, the generated salt solution is filtered to remove, the organic phase is washed with water to neutrality, and finally the epichlorohydrin is distilled under reduced pressure to obtain the hyperbranched epoxy resin liquid.

[0030] The third object of the present invention is to propose the use of the hyperbranched epoxy resin described in the first aspect or the hyperbranched epoxy resin obtained by the preparation method described in the second aspect in photocuring 3D printing.

[0031] The fourth object of the present invention is to provide a low-viscosity, low-volatile photosensitive resin composition, which comprises, by weight, 30-70 parts of a hyperbranched epoxy resin; 5-20 parts of an alicyclic epoxy resin, 5-20 parts of an acrylate compound; 3-7 parts of a photoinitiator, and 0.2-1 part of an auxiliary agent; 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-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, 1,4-cyclohexanedimethanol bis(3,4-epoxycyclohexanecarboxylate), and 3,4-epoxycyclohexylmethyl methacrylate;

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

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

[0035] And / or, the auxiliary agent includes a leveling agent and a defoaming agent.

[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 triphenylsulfonium hexafluoroantimonate, diphenyl-(4-phenylsulfonium) phenylsulfonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, and diphenyliodonium hexafluoroarsenate.

[0037] A fifth object of the present invention is to provide a 3D printed product, which is 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 described in the present invention has the following characteristics: (1) The spherical molecule has a hyperbranched structure, less segment entanglement, low crystallinity, low viscosity and high solubility, and the product is easy to clean; (2) The main chain of the molecule contains both a benzene ring and a flexible segment structure, providing high strength while also having good toughness; (3) The terminal flexible chain contains two ring structures that can be opened, and the reaction activity is relatively high. It can replace the proportion of the main high-viscosity epoxy resin in the traditional resin formula to a large extent, thereby reducing the viscosity of the photosensitive resin combination. The hyperbranched epoxy resin can be applied to 3D printing photocurable resin to meet the requirements of low viscosity, low volatility, high toughness and high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is an infrared spectrum of a hyperbranched epoxy resin prepared in one embodiment of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the preferred embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In one embodiment, a method for synthesizing a hyperbranched epoxy resin is provided, and the specific steps are as follows:

[0044] 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 then add solvent N,N-dimethylformamide (DMF), start stirring until TMA is completely dissolved, and react at 115°C for 3 hours. After the reaction is completed, remove the solvent by reduced pressure distillation, and the obtained crude product is precipitated and separated with deionized water, and vacuum dried to finally obtain a pale white solid, which is recorded as intermediate 1; the reaction process is:

[0045]

[0046] 2. Place intermediate 1 and trimellitic anhydride (TMA) in a molar ratio of 3:1 in a reactor, add solvent N,N-dimethylformamide (DMF), heat and stir until all substances are dissolved, add water-carrying agent xylene and catalyst p-toluenesulfonic acid, reflux under reduced pressure at 130°C for 3 hours, and remove the solvent by distillation under reduced pressure after the reaction to obtain a crude product, and then precipitate with methanol / water, centrifuge, and vacuum dry to finally obtain intermediate 2; the reaction process is:

[0047]

[0048] R1 is Same below;

[0049] 3. Weigh equal amounts of 2,7-dioxaspiro[4.4]nonane-1,3-dione and diethylene glycol and place them in a reactor, then add solvent N,N-dimethylformamide (DMF), stir evenly and react at 110°C for 3 hours. After the reaction, remove the solvent by distillation under reduced pressure, wash with water, and vacuum dry to obtain a liquid intermediate 3; the reaction process is as follows:

[0050]

[0051] 4. Place intermediate 2 and intermediate 3 in a molar ratio of 1:6 in a reactor, add solvent DMF, water-carrying agent xylene and a small amount of catalyst p-toluenesulfonic acid, and reflux under reduced pressure at 130°C for 3 hours. After the reaction is completed, remove the solvent by distillation under reduced pressure to obtain a crude product, which is then precipitated with methanol / water, centrifuged, and vacuum dried to finally obtain liquid intermediate 4.

[0052]

[0053] 5. The intermediate tetrakis and epichlorohydrin are placed in a reactor at a molar ratio of 1:6, a small amount of catalyst tetramethylammonium bromide is added, and the reaction is carried out in a 65°C water bath for 6 hours. After the reaction is completed, an aqueous sodium hydroxide solution of the same amount as epichlorohydrin is added, and the aqueous sodium hydroxide solution is dripped within 1 hour under reduced pressure, and the reaction is continued for half an hour, and the generated salt solution is filtered to remove the organic phase, and the epichlorohydrin is finally removed by reduced pressure distillation to obtain the hyperbranched epoxy resin liquid. The reaction process is:

[0054]

[0055] In the above examples, the prepared hyperbranched epoxy resin has the following characteristics: (1) the spherical molecule has a hyperbranched structure, less chain segment entanglement, low crystallinity, low viscosity and high solubility, and the product is easy to clean; (2) the main chain of the molecule contains both benzene rings and flexible chain segment structures, providing high strength and good toughness; (3) the terminal flexible chain contains two ring structures that can be opened, and the reaction activity is high. Therefore, it can be used in 3D printing light-curing resins to meet the requirements of low viscosity, low volatility, high toughness and high strength.

[0056] The prepared hyperbranched epoxy resin was subjected to infrared testing, and its infrared spectrum is shown as follows: Figure 1 In the infrared spectrum, 1033cm -1 The asymmetric stretching vibration peak of -COC- appears at 1103cm -1 The peak of CO stretching vibration is 600-800cm -1 There is no C-Cl characteristic absorption peak between them, indicating that the flexible chain at the end of the prepared hyperbranched epoxy resin has completed the epoxidation ring closure reaction well. -1 is the in-plane bending vibration peak of hydroxyl group, 1725cm -1 The stretching vibration peak of C=O is 2929cm -1 The stretching vibration peak of alkyl (-CH2- and -CH-), 3416 cm -1 is the stretching vibration peak of -OH. Combining the steps of the above preparation method and the infrared spectrum, it can be identified that the hyperbranched epoxy resin has the structural formula shown in Formula I:

[0057]

[0058] Among them, R2 is ~~ is the group connection point;

[0059] R1 is

[0060] The viscosity of the prepared hyperbranched epoxy resin was tested in accordance with ASTM D2196. Different test parameters were selected according to a rotor, rotation speed, and viscosity comparison table. The test showed that the viscosity of the prepared hyperbranched epoxy resin was 950 mPa·s.

[0061] In a preferred embodiment, the amount of N,N-dimethylformamide added as the solvent 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 reaction to proceed fully.

[0062] 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, and the amount of solvent N,N-dimethylformamide and water-carrying agent xylene added is not limited to a specific value, and is mainly used to adjust the viscosity of the system to facilitate the full reaction.

[0063] 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.

[0064] In another embodiment, a method for preparing a low-viscosity, low-volatile photosensitive material composition is provided, and the method is as follows: 30-70 parts by weight of a hyperbranched epoxy resin shown in Formula I, 5-20 parts by weight of an alicyclic epoxy resin, 5-20 parts by weight of an acrylic compound, 1.5-3 parts by weight of a free radical initiator, 1.5-4 parts by weight of a cationic initiator, 0.1-0.5 parts by weight of a leveling agent, and 0.1-0.5 parts by weight of a defoaming agent are put into a blender, mixed and stirred in the blender, and after being evenly dispersed, allowed to stand for natural defoaming to obtain a low-viscosity, low-volatile photosensitive material composition that can meet the requirements of high toughness and high strength after 3D printing.

[0065] In a preferred embodiment, the alicyclic epoxy resin is one or a mixture of any proportion of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, 1,4-cyclohexanedimethanol bis(3,4-epoxycyclohexanecarboxylate), 3,4-epoxycyclohexylmethyl methacrylate. The above alicyclic epoxy resin monomers are well known to technicians in the industry and can be purchased from Japan Daicel, Jiangsu Taitel, and Nantong Xinnaxi.

[0066] In a preferred embodiment, the acrylate compound is one or a mixture of any two or more of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 3(2-hydroxyethyl)isocyanuric acid triacrylate, di-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. The above photocurable acrylate monomers are well known to those skilled in the art and can be purchased from Sartomer Chemical Company, Allnex Corporation of the United States, Changxing Chemical, Kojin of Japan, and Miyuan of South Korea.

[0067] 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 triphenylsulfonium hexafluoroantimonate, diphenyl-(4-phenylsulfonium) phenylsulfonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, and diphenyliodonium hexafluoroarsenate.

[0068] In a preferred embodiment, the auxiliary agent is a leveling agent and a defoaming agent, and the auxiliary agent can be any commercially available auxiliary agent, such as Evonik TEGO leveling agent, BYK leveling agent, Digo defoaming agent and BYK defoaming agent.

[0069] In a preferred embodiment, the mixing speed is 300-800 r / min, the mixing temperature is 20-50° C., and the mixing time is 30-60 minutes.

[0070] The following are preferred implementation examples. If the manufacturer of the reagent or instrument is not specified in the examples, conventional products can be purchased from the market. If the specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer can be used.

[0071] Example 1

[0072] 1) Preparation of hyperbranched epoxy resin

[0073] Weigh 576 g of trimellitic anhydride (TMA) and place it in a reactor, weigh 318 g of diethylene glycol (DEG) at a molar ratio of 1:1, and then add 750 g of solvent N,N-dimethylformamide (DMF), start stirring until TMA is completely dissolved, and react at a constant temperature of 115°C for 3 hours. After the reaction is completed, the solvent DMF is removed by reduced pressure distillation, and the crude product is precipitated and separated with 50°C deionized water, and vacuum dried to finally obtain a pale white solid, which is recorded as intermediate product 1.

[0074] Weigh 192 g of trimellitic anhydride and place it in a reactor, weigh 894 g of intermediate product 1 at a molar ratio of 1:3, add 1000 g of solvent N,N-dimethylformamide (DMF), heat and stir until all substances are dissolved, then add 200 g of water-carrying agent xylene and 8.145 g of catalyst p-toluenesulfonic acid, reflux under reduced pressure at 130°C for 3 hours, and after the reaction is completed, remove the solvent by distillation under reduced pressure to obtain a crude product, which is then precipitated with methanol / water, centrifuged, and vacuum dried to finally obtain intermediate product 2.

[0075] Weigh 936 g of 2,7-dioxaspiro[4.4]nonane-1,3-dione and 636 g of diethylene glycol and place them in a reactor, then add 750 g of solvent N,N-dimethylformamide (DMF), stir evenly and react at a constant temperature of 110°C for 3 hours. After the reaction is completed, remove the solvent by distillation under reduced pressure, wash with water, and vacuum dry to obtain a liquid intermediate product 3.

[0076] 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 water-carrying xylene and 9.83g of catalyst p-toluenesulfonic acid. Reflux under reduced pressure at 130°C for 3 hours. After the reaction is completed, remove the solvent by distillation under reduced pressure to obtain a crude product. Then, precipitate with methanol / water, centrifuge and dry in vacuo to obtain a liquid intermediate product 4.

[0077] 1257 g of intermediate product 4 and 277.5 g of epichlorohydrin were weighed and placed in a reactor, 7.67 g of tetramethylammonium bromide as a catalyst was added, and the mixture was reacted in a 65° C. water bath for 6 hours. After the reaction, 300 g of a 40% sodium hydroxide aqueous solution was added, and the sodium hydroxide aqueous solution was dripped over within 1 hour under reduced pressure. The reaction was continued for another half an hour, and the generated salt solution was filtered out. The organic phase was washed with water until it was neutral, and finally the epichlorohydrin was removed by reduced pressure distillation to obtain the hyperbranched epoxy resin liquid.

[0078] 2) Preparation of 3D printing photosensitive resin composition

[0079] 30 parts by weight of a 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 triphenylsulfonium hexafluoroantimonate, 0.1 parts by weight of a leveling agent BYK 333, and 0.1 parts by weight of a defoaming agent BYK-024 were put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a low-viscosity, low-volatile photosensitive resin composition.

[0080] Example 2

[0081] 1) The preparation process of the hyperbranched epoxy resin is the same as that of Example 1;

[0082] 2) 50 parts by weight of a 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of a leveling agent BYK 333, and 0.2 parts by weight of a defoaming agent BYK-024 are put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a low-viscosity, low-volatile photosensitive resin composition.

[0083] Example 3

[0084] 1) The preparation process of the hyperbranched epoxy resin is the same as that of Example 1;

[0085] 2) 70 parts by weight of a 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 triphenylsulfonium hexafluoroantimonate, 0.5 parts by weight of a leveling agent BYK 333, and 0.5 parts by weight of a defoaming agent BYK-024 are put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a low-viscosity, low-volatile photosensitive resin composition.

[0086] Example 4

[0087] 1) The preparation process of hyperbranched epoxy resin is the same as that of Example 1

[0088] 2) 50 parts by weight of a 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of a leveling agent BYK 333, and 0.2 parts by weight of a defoaming agent BYK-024 are put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a low-viscosity, low-volatile photosensitive resin composition.

[0089] Example 5

[0090] 1) The preparation process of hyperbranched epoxy resin is the same as that of Example 1

[0091] 2) 30 parts by weight of a 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of a leveling agent BYK 333, and 0.2 parts by weight of a defoaming agent BYK-024 are put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a low-viscosity, low-volatile photosensitive resin composition.

[0092] Comparative Example 1

[0093] 50 parts by weight of bisphenol A 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of BYK 333 and 0.2 parts by weight of BYK-024 were put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a conventional photosensitive resin composition.

[0094] Comparative Example 2

[0095] 50 parts by weight of bisphenol A 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of BYK 333 and 0.2 parts by weight of BYK-024 were put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a photosensitive resin composition.

[0096] Comparative Example 3

[0097] 50 parts by weight of bisphenol A 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 polytetramethylene glycol, 20 parts by weight of ethoxylated trimethylolpropane triacrylate, 2 parts by weight of 1-hydroxy-cyclohexyl-phenyl ketone, 3 parts by weight of triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of BYK 333 and 0.2 parts by weight of BYK-024 were put into a stirrer, stirred at a speed of 500 r / min for 30 minutes at 25° C., and allowed to stand for defoaming to obtain a toughened photosensitive resin composition.

[0098] Comparative Example 4

[0099] 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 triphenylsulfonium hexafluoroantimonate, 0.2 parts by weight of BYK 333 and 0.2 parts by weight of BYK-024 were put into a stirrer, stirred at a speed of 500 r / min for 30 min at 25° C., and allowed to stand for defoaming to obtain a photosensitive resin composition.

[0100] Experimental example

[0101] The photosensitive resin compositions of the above-mentioned comparative examples 1-4 and embodiments 1-5 were introduced into the resin tank of the SLA type 3D printing equipment, and the sample preparation process parameters of the printing equipment were set to be consistent. Three groups of standard bending samples and three groups of standard impact samples were prepared by each printing, and the viscosity and volatility of each photosensitive resin composition were tested respectively.

[0102] 1. Bending performance test

[0103] The prepared standard bending sample was cured by UV lamp of the same power for 30 minutes, and then left at room temperature for 48 hours to ensure that the resin composition in the standard bending sample was completely cured. The bending strength of each resin composition after curing was tested according to ASTM D790-10 standard. The test results are shown in Table 1.

[0104] 2. Impact performance test

[0105] The prepared standard impact specimens were cured by UV lamps of the same power for 30 minutes, and then left 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. The test results are shown in Table 1.

[0106] 3. Resin viscosity test

[0107] The test was conducted according to ASTM D2196 standard, and different test parameters were selected according to the rotor, speed, and viscosity comparison table to collect the viscosity values ​​of each photosensitive resin composition. The test results are shown in Table 1.

[0108] 4. Resin volatility test

[0109] Disposable cups of the same size were used to take 100 g of the photosensitive resin composition, and placed in an oven at 60°C or 80°C with the cups uncovered, and weight data were collected for 3 days, 5 days, 7 days, 10 days, and 14 days, respectively. The test results are shown in Table 2.

[0110] Table 1: Properties of photosensitive resins in comparative examples and examples

[0111] 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

[0112] Table 2: Comparative Examples and Example Photosensitive Resin Volatility Test Results

[0113]

[0114] It is not difficult to see from Table 1 that the viscosity of the photosensitive resin provided by Examples 1-5 is basically controlled within 350mPa·s, and the bending strength, bending modulus and impact strength performance have obvious advantages; and it can be seen from Table 2 that the volatilization amount of the photosensitive resin is relatively small after adding the hyperbranched epoxy resin as the main body. In comparison, the data of Comparative Examples 1-3 show that conventional photosensitive resins must add a diluent (3-ethyl-3-hydroxymethyloxetane) to reduce the overall viscosity of the resin, but the addition of a diluent will result in a higher amount of resin volatilization. At the same time, the traditional formula can improve the impact toughness of the resin by adding a toughening agent, but it will also cause the resin strength to decrease. The data of Comparative Example 4 show that the dendritic epoxy resin can have a good toughening effect, but the viscosity of the dendritic epoxy resin is relatively high, and a diluent is also required to reduce the viscosity of the resin system.

[0115] From the above conclusions, it can be seen that after the hyperbranched epoxy resin is introduced as the main resin in the photosensitive resin composition of the present invention, the viscosity and volatility of the resin system are greatly reduced compared with the traditional resin by adjusting the remaining components. At the same time, the toughness and strength of the photosensitive resin composition of the present invention are also improved compared with the traditional resin, and the future commercialization prospects are broad.

[0116] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention 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 Formula I: Among them, R2 is ~~ is the group connection point; R1 is 2. The method for preparing a hyperbranched epoxy resin according to claim 1, wherein The steps include: S1. trimellitic anhydride and diethylene glycol undergo hydrolysis and esterification reaction at 110-120°C to obtain intermediate 1; S2. Intermediate 1 undergoes an esterification reaction with trimellitic anhydride in the presence of a water-carrying agent 1 and a catalyst 1 to obtain intermediate 2; S3. Intermediate 2 and intermediate 3 undergo esterification reaction in the presence of water-carrying agent 2 and catalyst 2 to obtain intermediate 4; intermediate 3 is obtained by hydrolysis and esterification reaction of 2,7-dioxaspiro[4.4]nonane-1,3-dione and diethylene glycol at 110-120°C; S4. The intermediate four reacts with epichlorohydrin in the presence of a catalyst three to undergo an esterification reaction, followed by dropwise addition of an alkaline solution to obtain a hyperbranched epoxy resin of formula I; The structural formulas of the intermediate 1, intermediate 2, intermediate 3 and intermediate 4 are respectively:

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 the intermediate 1 to trimellitic anhydride is 3:1; And / or, in step S3, the molar ratio of 2,7-dioxaspiro[4.4]nonane-1,3-dione to diethylene glycol is 1:1; And / or, in step S3, the molar ratio of the intermediate 2 to the intermediate 3 is 1:6; And / or, in step S4, the molar ratio of the intermediate four to epichlorohydrin is 1:6; And / or, in step S4, the base is an inorganic base, and the molar ratio of the base to epichlorohydrin is 1:

1.

4. The preparation method according to claim 2, characterized in that: The water-carrying agent 1 and the water-carrying agent 2 are xylene; And / or, the catalyst 1 and the catalyst 2 are each independently selected from one of p-toluenesulfonic acid, thionyl chloride and trifluoromethanesulfonic acid; And / or, the catalyst three is tetramethylammonium bromide.

5. The preparation method according to claim 2, characterized in that: In steps S1-S4, the solvent used in the preparation process of intermediate 1, intermediate 2, intermediate 3 or intermediate 4 is N,N-dimethylformamide.

6. The preparation method according to claim 2, characterized in that: In step S4, the alkaline solution reaction dropwise addition reaction process is completed within 1 hour under reduced pressure, and the reaction is continued for half an hour, the generated salt solution is filtered to remove, the organic phase is washed with water to neutrality, and finally the epichlorohydrin is distilled under reduced pressure to obtain the hyperbranched epoxy resin liquid.

7. Use of the hyperbranched epoxy resin according to claim 1 or the hyperbranched epoxy resin obtained by the preparation method according to any one of claims 2 to 6 in photocuring 3D printing.

8. A low-viscosity, low-volatility photosensitive resin composition, characterized in that: The components include, by weight, 30-70 parts of a hyperbranched epoxy resin; 5-20 parts of an alicyclic epoxy resin, 5-20 parts of an acrylate compound; 3-7 parts of a photoinitiator, and 0.2-1 part of an auxiliary agent; the hyperbranched epoxy resin is the hyperbranched epoxy resin according to claim 1 or the hyperbranched epoxy resin obtained by the preparation method according to 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-epoxycyclohexylcarboxylate, bis((3,4-epoxycyclohexyl)methyl)adipate, 1,4-cyclohexanedimethanol bis(3,4-epoxycyclohexanecarboxylate), and 3,4-epoxycyclohexylmethyl methacrylate; And / or, the acrylate compound is one of ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 3(2-hydroxyethyl)isocyanuric acid triacrylate, di-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate and dipentaerythritol hexaacrylate. and / or, the photoinitiator comprises a free radical photopolymerization initiator and a cationic photopolymerization initiator; And / or, the auxiliary agent includes a leveling agent and a defoaming agent.

10. A 3D printed product obtained by 3D printing and curing the resin composition according to claim 9.

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