Photo-thermal dual-curing hyperbranched resin, synthetic method and ultraviolet curing resin composition for 3D printing

Abstract

The invention relates to photo-thermal dual-curing hyperbranched resin, a synthesis method and an ultraviolet curing resin composition for 3D printing. The invention relates to a synthetic method of photo-thermal dual-cured hyperbranched resin. The synthetic method comprises the following steps: adding isocyanate and a catalyst 1 into a reaction kettle at 55-60 DEG C; 2, 2-dimethylolbutyric acid is dissolved in a diluent, then dropwise added and subjected to a heat preservation reaction until an intermediate product A1 is obtained; adding a catalyst 2, and continuously reacting at 65-70 DEG C to obtain an intermediate product A2; and cooling to 55-60 DEG C, dropwise adding a mixture of tert-butylaminoethyl methacrylate and a polymerization inhibitor, and carrying out a heat preservation reaction until the isocyanate value is less than 0.5% to obtain the photo-thermal dual-curing hyperbranched resin, which has the characteristics of low viscosity, high functionality, high activity and reduced volume shrinkage, can be used for preparing an ultraviolet curing resin composition for 3D printing, and has wide application prospects. The material has high rigidity and good toughness at the same time.

Description

Technical Field

[0001] The present application relates to the field of ultraviolet light-cured 3D printing materials, and more specifically, to a hyperbranched resin capable of photothermal dual curing and a synthesis method thereof, as well as an ultraviolet light-cured resin composition for 3D printing. Background Art

[0002] With the rapid development of the manufacturing industry, 3D printing technology has gradually emerged with its unique flexibility and efficiency, especially in the fields of rapid prototyping, small batch customization and complex structural parts manufacturing. Among them, 3D printing technology based on resin materials has shown great potential in injection mold manufacturing and has become an effective supplement to metal molds in specific application scenarios. Resin molds can not only effectively reduce production costs and shorten product development cycles, but also quickly verify the feasibility and manufacturability of product designs during the trial production stage, providing valuable data support for subsequent mass production.

[0003] However, the resin materials for 3D printing injection molds on the market still face many challenges in performance and application, which are specifically reflected in the following aspects: 1. Brittleness problem: Although the existing high-temperature resistant 3D printing mold resin can maintain good stability in high temperature environments, that is, it has a high heat deformation temperature and rigidity, the brittleness of the material itself limits its application range. In actual use, the mold is prone to cracking and breaking due to external impact or internal stress concentration, which not only affects the service life of the mold, but also increases the risk and cost in the production process.

[0004] 2. Volume shrinkage and deformation problems: Resin materials often shrink significantly during the curing process. Especially when printing large or regular-shaped models, this volume change may cause the model to bend and deform, seriously affecting the dimensional accuracy and surface quality of the model. In addition, the large volume change also makes it difficult to directly apply the printed model to the injection molding machine, limiting its direct application in industrial production.

[0005] 3. Material stability and storage problems: In order to increase the heat deformation temperature, a large amount of solid multifunctional resins with rigid rings are usually added in the prior art. However, this type of resin has a high viscosity. Although it can effectively improve the heat resistance of the material, it also brings problems such as increased viscosity and poor storage stability. For example, high-viscosity resins are prone to solid precipitation during storage, especially in low-temperature environments. The entire formula may become completely solid, which brings great inconvenience to use and also affects the performance stability of the printed model.

[0006] Therefore, the existing 3D printing injection mold resin materials have problems in terms of brittleness, volume shrinkage and deformation, material stability and storage, which seriously restrict their wide application in high-precision and high-demand 3D printing scenarios. Therefore, developing a UV-curable resin for 3D printing that has excellent heat resistance, rigidity and toughness, will not crack or break, and can effectively control volume shrinkage and improve material storage stability is of great significance for promoting the further development of 3D printing technology in the field of injection mold manufacturing. Summary of the invention

[0007] In order to solve the above problems, the present application provides a photothermal dual-curable hyperbranched resin for 3D printing and a synthesis method thereof, as well as a UV-curable resin composition.

[0008] In a first aspect, the present application provides a method for synthesizing a hyperbranched resin capable of photothermal dual curing, using the following technical solution: A method for synthesizing a hyperbranched resin capable of dual photo-thermal curing comprises the following steps: Step 1: Heat the reactor to 55-60°C, add isocyanate and catalyst 1 into the reactor, and stir evenly; The isocyanate comprises at least one or more of toluene diisocyanate, p-phenylene diisocyanate and isophorone diisocyanate; Catalyst 1 comprises at least a mixture of one or more of dibutyltin dilaurate, stannous octoate, and organic bismuth; the amount of catalyst 1 is 0.05-0.3% of the mass of isocyanate; Step 2: 2,2-dihydroxymethylbutyric acid and a diluent are mixed evenly, and then added dropwise to a reaction kettle at a certain speed. After the addition is completed, the mixture is heated to 55-60° C. to react to obtain an intermediate product A1; The molar ratio of 2,2-dihydroxymethylbutyric acid to isocyanate is 1:2; Step 3: Add catalyst 2 and control the temperature at 65°C-70°C to allow intermediate product A1 to continue to react to obtain intermediate product A2; Catalyst 2 comprises at least a mixture of one or more of magnesium stearate, tributylphosphine and triethylenediamine; The amount of catalyst 2 is 0.01-0.1% of the total mass of isocyanate and 2,2-dimethylolbutyric acid; Step 4: After cooling to 55-60°C, tert-butylaminoethyl methacrylate and the polymerization inhibitor are mixed evenly, and then added dropwise to the reactor at a certain speed. After the addition is completed, the reaction is kept at 55-60°C until the isocyanate value is less than 0.5%, thereby obtaining the final product A3, which is a hyperbranched resin with dual photothermal curing.

[0009] In this step, since the isocyanate is terminated with a monomer such as tert-butylaminoethyl methacrylate (TBAEMA), the isocyanate will be released after heating. The isocyanate can further cross-link with the polyol (thermosetting) as the temperature rises, so that the material has high rigidity and good toughness.

[0010] By adopting the above technical scheme, the photothermal dual-curable hyperbranched resin synthesized by the present invention has the characteristics of low viscosity, high functionality, and high activity, and has a highly branched three-dimensional structure, and has the potential to reduce volume shrinkage, thereby solving the problem of model bending deformation due to volume change when 3D printing large or regular-shaped models, thereby improving the overall accuracy of the printed model; on the other hand, the resin has photothermal dual-curing characteristics, in addition to curing under ultraviolet light, it can also be thermally cured, that is, at a certain temperature, the terminal isocyanate can be unblocked, and as the temperature increases, the isocyanate can further cross-link, so that the cross-linking degree and molecular weight of the material will be greatly improved, so that the material has high rigidity and good toughness, thereby solving the problem of cracking, breaking and bending deformation of the model during printing and use; in addition, compared with the high-viscosity solid multifunctional resin with a rigid ring used in the prior art, the photothermal dual-curable hyperbranched resin synthesized by the present invention has a low viscosity, will not precipitate from the formula during storage, will not become solid at low temperatures, and has a high heat deformation temperature, thereby solving the problems of storage and stability.

[0011] Preferably, the diluent is morpholine acrylate, and the amount of the diluent is 40-60% of the total mass of the isocyanate and the 2,2-dihydroxymethylbutyric acid.

[0012] Preferably, the polymerization inhibitor comprises at least one of p-hydroxyanisole, hydroquinone and p-tert-butylcatechol.

[0013] Preferably, the polymerization inhibitor comprises at least one of p-hydroxyanisole, hydroquinone and p-tert-butylcatechol; and the dosage of the polymerization inhibitor is 0.1-0.3% of the mass of tert-butylaminoethyl methacrylate.

[0014] Preferably, in step 2, the dripping speed of the mixture of 2,2-dihydroxymethylbutyric acid and the diluent is 25-35 mL / min; in step 4, the dripping speed of the mixture of tert-butylaminoethyl methacrylate and the inhibitor is 25-35 mL / min.

[0015] The reaction process of the above steps 1-4 is shown as follows: In a second aspect, the present application provides a hyperbranched resin that can be cured both photothermally and optically.

[0016] In a third aspect, the present application provides an application of a hyperbranched resin that can be cured both photothermally and in the preparation of a resin composition for 3D printing injection molds.

[0017] In a fourth aspect, the present application provides a UV-curable resin composition for 3D printing, which adopts the following technical solution: A UV-curable resin composition for 3D printing comprises the following raw materials in percentage by mass: 20-30% of the above-mentioned synthesized hyperbranched resin capable of photothermal dual curing, 5-8% of polyol, 25-45% of aluminum oxide, 1.5-2.5% of initiator, 25-35% of monomer and 0.1-0.5% of auxiliary agent.

[0018] Among them, the hyperbranched resin that can be cured by both light and heat can be cured under ultraviolet light. At a certain temperature, the isocyanate at the end can be unblocked. As the temperature rises, the isocyanate and polyol react. At this time, the cross-linking degree and molecular weight of the material will be greatly improved, making the material have high rigidity and high heat deformation temperature while also having a certain toughness. In practical applications, problems such as model cracking and breakage are not likely to occur.

[0019] Limiting the dosage and matching relationship of the raw materials used can effectively improve the stability and mechanical properties of the resulting material during the curing process, ensure the dimensional accuracy and heat resistance of the 3D printing injection mold resin composition after molding, and reduce the risk of deformation of the model during the printing process.

[0020] Preferably, the polyol is a polycaprolactone triol modified with polypropylene glycol, with a molecular weight of 4000 and 42 hydroxyl groups, purchased from Hunan Juren Chemical New Material Technology Co., Ltd., with a product model of 3400P.

[0021] Preferably, the monomer comprises at least one of dipentaerythritol hexaacrylate and tricyclodecane dimethanol diacrylate.

[0022] Preferably, the alumina is spherical alumina powder with a mesh size of 10000-15000.

[0023] In a fifth aspect, the present application provides a method for preparing a UV-curable resin composition for 3D printing.

[0024] A method for preparing a UV-curable resin composition for 3D printing comprises the following steps: mixing the photothermal dual-curable hyperbranched resin, polyol, alumina, an initiator, a monomer and an auxiliary agent at 55-60° C. until uniform, to obtain a UV-curable resin composition for 3D printing.

[0025] The thermal curing reaction of the above-mentioned UV-curable resin composition for 3D printing is schematically shown as follows: In summary, this application has the following beneficial effects: 1. By synthesizing a hyperbranched resin that can be cured both photothermally and optically, the brittleness of the mold resin material is significantly reduced, its toughness is improved, and the problem of cracking and breakage of the mold during use is effectively avoided.

[0026] 2. The highly branched three-dimensional structure of the hyperbranched resin that can be cured by both light and heat effectively reduces the volume shrinkage of the material during the curing process, avoids the bending deformation of large or regular-shaped 3D printed models, and improves the overall accuracy and surface quality of the model.

[0027] 3. The hyperbranched resin that can be cured by both light and heat has low viscosity, which improves the storage stability of the mold resin material, reduces the precipitation of solid multifunctional resin during storage, ensures the fluidity of the material under low temperature conditions, and improves the performance stability and consistency of the printed model.

[0028] 4. The hyperbranched resin that can be cured by both light and heat has the characteristics of dual curing by both light and heat. It can not only be cured under ultraviolet light, but also the terminal isocyanate can be unblocked at a certain temperature and further cross-linked with polyol at high temperature. The cross-linking degree and molecular weight of the prepared resin composition are greatly improved, so that the material has high rigidity and good toughness at the same time, so that problems such as model cracking and breakage will not occur during 3D printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a design drawing for model preparation and processing of the ultraviolet light-curable resin composition for 3D printing of Example 1 in a performance testing experiment.

[0030] Figure 2 This is a printing diagram of the ultraviolet light-curable resin composition for 3D printing of Example 1 in a performance testing experiment.

[0031] Figure 3 This is a diagram of model cleaning after a model is printed using the ultraviolet light-curable resin composition for 3D printing of Example 1 in a performance testing experiment.

[0032] Figure 4 This is a picture showing that the model of the UV-curable resin composition for 3D printing of Example 1 is placed in a curing box in a performance testing experiment.

[0033] Figure 5 This is a picture of a finished model printed by the ultraviolet light-curable resin composition for 3D printing of Example 1 in a performance testing experiment. DETAILED DESCRIPTION

[0034] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0035] The raw materials used in the following examples and comparative examples are all commercially available products. Example

[0036] A UV-curable resin composition for 3D printing, and a preparation method thereof is as follows: Step 1: Synthesis of hyperbranched resin capable of dual curing by light and heat Step 1: After the reactor is heated to 55°C-60°C, isocyanate and catalyst 1 are added in sequence and stirred evenly.

[0037] The isocyanate is a mixture of one or more of toluene diisocyanate, p-phenylene diisocyanate and isophorone diisocyanate.

[0038] Catalyst 1 is a mixture of one or more of dibutyltin dilaurate, stannous octoate and organic bismuth.

[0039] The amount of catalyst 1 used is 0.01-0.3% of the mass of isocyanate.

[0040] Step 2: Dissolve 2,2-dihydroxymethylbutyric acid (DMBA) in a diluent, and add it dropwise into the reactor at a rate of 25-35 mL / min. After the addition is completed, keep the reaction at 55°C-60°C until the isocyanate value reaches a specified value to obtain the intermediate product A1.

[0041] The molar ratio of 2,2-dimethylolbutyric acid to isocyanate is 1:2.

[0042] The diluent is acrylic acid morpholine (ACMO), and the amount used is 40-60% of the total mass of isocyanate and 2,2-dihydroxymethylbutyric acid.

[0043] Step 3: Add catalyst 2 into the reactor, raise the temperature to 65°C-70°C and keep the temperature to react until the isocyanate value reaches the specified value to obtain the intermediate product A2.

[0044] Catalyst 2 is a mixture of one or more of magnesium stearate, tributylphosphine and triethylenediamine.

[0045] The amount of catalyst 2 used is 0.01-0.1% of the total mass of isocyanate and 2,2-dihydroxymethylbutyric acid.

[0046] Step 4: After cooling to 55-60°C, tert-butylaminoethyl methacrylate (TBAEMA) and the polymerization inhibitor are mixed evenly, and then added dropwise into the reactor at a rate of 25-35 mL / min. After the addition is completed, the reaction is kept at 55°C-60°C until the isocyanate value is less than 0.5%, and the product A3 is obtained, which is a hyperbranched resin with dual photothermal curing.

[0047] The polymerization inhibitor is a mixture of one or more of p-hydroxyanisole, hydroquinone and p-tert-butylcatechol.

[0048] The dosage of the polymerization inhibitor is 0.1-0.3% of the mass of tert-butylaminoethyl methacrylate.

[0049] In the above steps, the determination method of isocyanate value refers to the standard: HG / T 2409-2023 Determination of isocyanate content in polyurethane prepolymer.

[0050] Step 2: Preparation of the composition The photothermal dual-curable hyperbranched resin prepared in step 1 is mixed with polyol, alumina, an initiator, a monomer, and an auxiliary agent at 55° C.-60° C. until uniformly mixed to obtain a UV-curable resin composition for 3D printing.

[0051] According to the mass percentage, the photo-thermal dual-curable hyperbranched resin is 20-30%, the polyol is 5-8%, the aluminum oxide is 25-45%, the initiator is 1.5-2.5%, the monomer is 25-35%, and the auxiliary agent is 0.1-0.5%.

[0052] The polyol is a polycaprolactone triol modified with polypropylene glycol, with a molecular weight of 4000 and 42 hydroxyl groups, purchased from Hunan Juren Chemical New Material Technology Co., Ltd., with a product model of 3400P.

[0053] Alumina is spherical aluminum oxide powder, 10000-15000 mesh.

[0054] The initiator is TPO.

[0055] The monomer is a mixture of one or more of dipentaerythritol hexaacrylate and tricyclodecane dimethanol diacrylate.

[0056] Example 1 A UV-curable resin composition for 3D printing, and a preparation method thereof is as follows: Step 1: Synthesis of hyperbranched resin capable of dual curing by light and heat Step 1: After the reactor is heated to 58°C, isocyanate and catalyst 1 are added in sequence and stirred evenly.

[0057] The isocyanate is isophorone diisocyanate.

[0058] Catalyst 1 is organic bismuth.

[0059] The amount of catalyst 1 used is 0.1% of the mass of isocyanate.

[0060] Step 2: Dissolve 2,2-dihydroxymethylbutyric acid in a diluent, and add it dropwise into the reaction kettle at a rate of 30 mL / min. After the addition is completed, keep the reaction at 58° C. to obtain the intermediate product A1.

[0061] The molar ratio of 2,2-dimethylolbutyric acid to isocyanate is 1:2.

[0062] The diluent is morpholine acrylate, and the amount used is 50% of the total mass of isocyanate and 2,2-dihydroxymethylbutyric acid.

[0063] Step 3: Add catalyst 2 into the reactor, raise the temperature to 68°C, and keep the temperature to react until the isocyanate value reaches the calculated value to obtain the intermediate product A2.

[0064] Catalyst 2 is magnesium stearate.

[0065] The amount of catalyst 2 used is 0.05% of the total mass of isocyanate and 2,2-dihydroxymethylbutyric acid.

[0066] Step 4: Cool down to 58°C, mix tert-butylaminoethyl methacrylate and the polymerization inhibitor evenly, and then drip into the reactor at a rate of 30 mL / min. After the dripping is completed, keep the temperature at 58°C for reaction until the isocyanate value is less than 0.5%, and obtain product A3, which is a hyperbranched resin with dual photothermal curing.

[0067] The inhibitor is p-hydroxyanisole.

[0068] The amount of the polymerization inhibitor used is 0.15% of the mass of tert-butylaminoethyl methacrylate.

[0069] Step 2: Preparation of the composition According to the mass percentage, 25% of the photothermal dual-curable hyperbranched resin prepared in step 1 was mixed with 5% of polyol, 40% of aluminum oxide, 1.5% of initiator, 28.2% of monomer, and 0.3% of auxiliary agent at 58° C. until uniform, to obtain a UV-curable resin composition for 3D printing.

[0070] The polyol refers to polycaprolactone triol modified with polypropylene glycol, with a molecular weight of 4000 and 42 hydroxyl groups.

[0071] Alumina is spherical aluminum oxide powder, 12500 mesh.

[0072] The initiator is TPO.

[0073] The monomers were 15% dipentaerythritol hexaacrylate and 13.2% tricyclodecane dimethanol diacrylate.

[0074] The additive is BYK410.

[0075] The amounts of raw materials used to prepare the hyperbranched resin capable of dual photo-thermal curing are shown in Table 1, and the amounts of raw materials used to prepare the UV-curable resin composition for 3D printing are shown in Table 2.

[0076] Embodiment 2-5 A UV-curable resin composition for 3D printing, the main preparation method of which is the same as that of Example 1, except that: the selection and dosage of some raw materials in step 1 and step 2 are different, see Table 1 and Table 2 for details.

[0077] Comparative Example Comparative Example 1 A resin composition for 3D printing, the main preparation method of which is the same as that of Example 1, except that: The monomer used in step 4 is hydroxyethyl acrylate (HEA) instead of tert-butylaminoethyl methacrylate (TBAEMA) in Example 1.

[0078] Comparative Example 2 A resin composition for 3D printing, which is different from Example 1 in that polyol is omitted.

[0079] Comparative Example 3 A resin composition for 3D printing, which is different from Example 2 in that polyol is omitted.

[0080] Comparative Example 4 A resin composition for 3D printing, which is different from Example 3 in that the polyol is omitted.

[0081] The specific ingredients and amounts of the above Examples 1-5 and Comparative Examples 1-4 are shown in Table 1 and Table 2.

[0082] Table 1 Table 2 Performance Testing The resin compositions prepared in Examples 1-5 and Comparative Examples 1-4 were used to perform 3D printing on models, and the performance of the models was tested. The performance data are recorded in Table 3.

[0083] 1. The relevant parameters and operations of printing the model are as follows: 1. 3D printing equipment parameters: top-pull 450nm LCD 3D printer, light source intensity 5000uw / cm 2 , slice thickness 0.05mm, layer exposure time 4.5s, bottom layer exposure time 60s.

[0084] 2. Post-processing method of printed model: 1) Place the model in 95% alcohol and use an ultrasonic cleaner to clean it for 3 minutes. Replace the alcohol with clean alcohol and then clean it again for 3 minutes. 2) After the UV curing box is kept at a constant temperature of 50°C, place the model in the curing box and turn on the UV lamp in the curing box to cure at a constant temperature for 30 minutes; 3) Place the model in an oven at 120°C for thermal curing for 120 minutes.

[0085] The relevant process diagram of Example 1 is shown in FIG. Figure 1-5 .

[0086] 2. The reference standards for performance testing are as follows: 1. Bending strength test method: GB / T 9341-2008 "Determination of flexural properties of plastics".

[0087] 2. Impact strength test method: GB / T 1843-2008 "Determination of cantilever beam impact strength of plastics".

[0088] 3. Volume shrinkage test method: Shrinkage = (ρ after - ρ before) / ρ after × 100%, where ρ after and ρ before are the densities after and before curing, respectively.

[0089] Description of test indicators: Toughness is reflected by the test index of impact strength, and rigidity is reflected by the index of bending strength. That is, the higher the impact strength, the better the toughness of the material; the higher the bending strength, the better the rigidity of the material.

[0090] Table 3 According to Table 3, by comparing the test results of Examples 1-5 and Comparative Examples 1-4 above, it can be seen that: 1. The UV-curable resin compositions of Examples 1-5 are as follows: in the hyperbranched resin capable of both light and heat curing synthesized in step 1, the isocyanate is capped with a monomer such as tert-butylaminoethyl methacrylate (TBAEMA), and thus the isocyanate will be released after heating. As the temperature rises, this part of the isocyanate and the polyol undergo a cross-linking reaction (thermal curing), and at this time, the cross-linking degree and molecular weight of the material will be greatly improved, thereby improving the toughness of the material while having high rigidity.

[0091] In the synthesis reaction of the hyperbranched resin capable of dual photo-thermal curing in Comparative Example 1, the monomer hydroxyethyl acrylate (HEA) is used for end-capping. However, HEA has no way to decapsulate isocyanate under thermal curing. Therefore, although polyols are added to the resin composition formula, the relevant effects cannot be exerted. On the contrary, since the polyols cannot participate in the reaction, the material properties tend to deteriorate.

[0092] According to the test data in Table 3, the UV-curable resin compositions of Examples 1-5 show good performance of both rigidity and toughness in the test compared with Comparative Examples 1-4. The improvement of material toughness solves the problems of cracking and fragility of 3D printed models caused by too strong rigidity; at the same time, it can also reduce volume shrinkage, and the shrinkage rate of Examples 1-5 is reduced to less than 3.6%.

[0093] 1. The difference between the resin composition of Comparative Example 2 and Example 1 is that no polyol is used in Comparative Example 2. Since no polyol is added to the composition, it means that thermal curing cannot work, so there is no way to achieve toughening, and the impact strength of the material is low; similarly, the difference between Comparative Example 3 and Example 2, and between Comparative Example 4 and Example 3 is the same.

[0094] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for synthesizing a hyperbranched resin capable of dual curing by light and heat, characterized in that: The following steps are involved: Step 1: Heat the reactor to 55-60°C, add isocyanate and catalyst 1 into the reactor, and stir evenly; The isocyanate comprises at least one or more of toluene diisocyanate, p-phenylene diisocyanate and isophorone diisocyanate; Catalyst 1 comprises at least a mixture of one or more of dibutyltin dilaurate, stannous octoate, and organic bismuth; the amount of catalyst 1 is 0.05-0.3% of the mass of isocyanate; Step 2: 2,2-dihydroxymethylbutyric acid and a diluent are mixed evenly, and then added dropwise to a reaction kettle at a certain speed. After the addition is completed, the mixture is heated to 55-60° C. to react to obtain an intermediate product A1; The molar ratio of 2,2-dihydroxymethylbutyric acid to isocyanate is 1:2; Step 3: Add catalyst 2 and control the temperature at 65°C-70°C to allow intermediate product A1 to continue to react to obtain intermediate product A2; Catalyst 2 comprises at least a mixture of one or more of magnesium stearate, tributylphosphine and triethylenediamine; The amount of catalyst 2 is 0.01-0.1% of the total mass of isocyanate and 2,2-dimethylolbutyric acid; Step 4: After cooling to 55-60°C, tert-butylaminoethyl methacrylate and the polymerization inhibitor are mixed evenly, and then added dropwise to the reactor at a certain speed. After the addition is completed, the reaction is kept at 55-60°C until the isocyanate value is less than 0.5%, thereby obtaining the final product A3, which is a hyperbranched resin with dual photothermal curing.

2. The method for synthesizing a hyperbranched resin capable of photothermal dual curing according to claim 1, characterized in that: The diluent is morpholine acrylate, and the amount of the diluent is 40-60% of the mass of the isocyanate and the 2,2-dihydroxymethylbutyric acid.

3. The method for synthesizing a hyperbranched resin capable of photothermal dual curing according to claim 1, characterized in that: The polymerization inhibitor contains at least one of p-hydroxyanisole, hydroquinone and p-tert-butylcatechol; the dosage of the polymerization inhibitor is 0.1-0.3% of the mass of tert-butylaminoethyl methacrylate.

4. The method for synthesizing a hyperbranched resin capable of photothermal dual curing according to claim 1, characterized in that: In the step 2, the dripping speed of the mixture of 2,2-dihydroxymethylbutyric acid and the diluent is 25-35 mL / min; in the step 4, the dripping speed of the mixture of tert-butylaminoethyl methacrylate and the polymerization inhibitor is 25-35 mL / min.

5. A photo-thermal dual-curable hyperbranched resin prepared by the synthesis method of the photo-thermal dual-curable hyperbranched resin according to any one of claims 1 to 4.

6. Use of the hyperbranched resin capable of dual photo-thermal curing as claimed in claim 5 in preparing a resin composition for 3D printing injection molds.

7. A UV-curable resin composition for 3D printing, characterized in that: According to mass percentage, the following raw materials are included: 20-30% of the hyperbranched resin capable of dual curing by light and heat as claimed in claim 6, 5-8% of polyol, 25-45% of aluminum oxide, 1.5-2.5% of initiator, 25-35% of monomer and 0.1-0.5% of auxiliary agent.

8. The UV-curable resin composition for 3D printing according to claim 7, characterized in that: The polyol is polycaprolactone triol modified with polypropylene glycol.

9. The UV-curable resin composition for 3D printing according to claim 7, characterized in that: The monomer includes at least one of dipentaerythritol hexaacrylate and tricyclodecane dimethanol diacrylate.

10. The method for preparing the UV-curable resin composition for 3D printing according to any one of claims 7 to 9, characterized in that: Under the condition of 55-60° C., the photo-thermal dual-curable hyperbranched resin, polyol, aluminum oxide, initiator, monomer and auxiliary agent are mixed until uniform to obtain a UV-curable resin composition for 3D printing.

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