Photo-thermal dual-curing resin composition as well as preparation method and application thereof

Abstract

The invention discloses a photo-thermal dual-curing resin composition as well as a preparation method and application thereof. The photo-thermal dual-curing resin composition is prepared from the following raw material components in percentage by mass: 40 to 70 percent of blocked polyurethane oligomer, 30 to 50 percent of reactive diluent, 2 to 15 percent of diamine chain extender with multiple hydrogen bonds and 0.5 to 3 percent of photoinitiator. The photo-thermal dual-curing resin composition provided by the invention is low in viscosity and good in stability, and can meet the printing requirements of a photo-curing 3D printer at normal temperature, and a printed product has the characteristics of high strength and high toughness.

Description

Technical Field

[0001] The present invention belongs to the field of 3D printing materials, and particularly relates to a photo-thermal dual-curing resin composition, a preparation method thereof, and an application thereof. Background Art

[0002] Among the many cutting-edge fields of 3D printing, photo-curing 3D printing has advantages such as high precision, high speed, and high flexibility. Its principle is based on the fact that under specific wavelength light irradiation, a photoinitiator causes a liquid photosensitive resin to undergo a polymerization reaction, curing and stacking layer by layer, and finally constructing a three-dimensional solid model. Compared with traditional manufacturing processes, it breaks through the limitations of complex geometric shapes and can easily achieve fine internal structures and unique appearance designs, providing infinite possibilities for product innovation. However, photo-curing 3D printing often has poor mechanical properties due to incomplete photopolymerization effect and insufficient molecular weight growth. By increasing the ratio of high molecular oligomers in the photosensitive resin system, the mechanical properties of the elastomer can be optimized, but it will cause a sharp increase in the viscosity of the photosensitive resin, hindering its 3D printing.

[0003] Photo-thermal dual-curing cleverly combines the characteristics of photo-curing and thermal-curing. It uses a photoinitiator to quickly initiate a polymerization reaction under light irradiation to achieve initial curing, and at the same time, further promotes the cross-linking and curing of the material by means of thermal-curing, greatly improving the performance and stability of the material. Carbon Company in the United States reported a resin that can be photo-thermally dual-cured. Its material form is a two-component: blocked polyurethane acrylate and polyol / amine chain extender. After the resin is cured by ultraviolet light and then heat-treated, the blocked polyurethane is deblocked to release isocyanate groups and react with the chain extender to form a high polymer, thereby obtaining a high-performance material. The two components of such a resin will react with each other, resulting in an increase in system viscosity and even gelation, poor storage stability. Usually, it needs to be mixed before use, and the viscosity is relatively high, making it difficult to meet the printing requirements of a photo-curing 3D printer at room temperature. Summary of the Invention

[0004] In order to solve at least one of the above problems, the present invention provides a photo-thermal dual-curing resin composition, a preparation method thereof, and an application thereof. The photo-thermal dual-curing resin composition provided by the present invention has low viscosity, good stability, and can meet the printing requirements of a photo-curing 3D printer at room temperature. The printed products thereof have the characteristics of high strength and high toughness.

[0005] In order to achieve the above object, the present invention adopts the following technical means: The first aspect of the present invention provides a photo-thermal dual-curing resin composition, and the raw material components included in the photo-thermal dual-curing resin composition and the mass percentages of each component are as follows: Blocked polyurethane oligomer 40 - 70% Reactive diluent 30 - 50% Diamine chain extender with multiple hydrogen bonds: 2 - 15% Photoinitiator: 0.5 - 3%.

[0006] In some embodiments of the present invention, the structural formula of the diamine chain extender with multiple hydrogen bonds is as follows:

[0007] Wherein, "R1" represents an isocyanate linking segment; "R2" represents a dihydrazide linking segment.

[0008] In some embodiments of the present invention, the preparation method of the diamine chain extender with multiple hydrogen bonds includes the following steps: S1. Weigh N,N - dihydroxyethyl oxamide, diisocyanate and an appropriate amount of solvent and place them in a reactor for mixing. The molar ratio of -OH to -NCO in N,N - dihydroxyethyl oxamide and diisocyanate is 1:(1.8 - 2.2). Then add an organotin catalyst accounting for 0.01% - 0.1% of the total weight of N,N - dihydroxyethyl oxamide and diisocyanate. Keep this system at a constant temperature of 50 - 80°C in a nitrogen atmosphere for 2 - 5 hours to obtain an isocyanate intermediate.

[0009] S2. Slowly drop the isocyanate intermediate obtained in step S1 into a reactor containing dihydrazide and an appropriate amount of solvent. The molar ratio of -NH2 to -NCO in dihydrazide and the isocyanate intermediate is 1:(1.8 - 2.2). Keep this system at a constant temperature of 90 - 150°C in a nitrogen atmosphere for 2 - 5 hours, and remove the solvent to obtain the diamine chain extender with multiple hydrogen bonds.

[0010] In some embodiments of the present invention, the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate; the organotin catalyst is dibutyltin dilaurate; the dihydrazide is one or more of malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, pimelic dihydrazide, azelaic dihydrazide, sebacic dihydrazide, isophthalic dihydrazide; the solvent is one or more of tetrahydrofuran, ether, toluene, acetone, N,N - dimethylformamide, N,N - dimethylacetamide; further preferably, the solvent is N,N - dimethylformamide.

[0011] The synthesis route of the diamine chain extender with multiple hydrogen bonds is as follows:

[0012] In some embodiments of the present invention, the structural formula of the blocked polyurethane oligomer is as follows:

[0013] Among them, " " represents a diol linking segment; "R" represents an isocyanate linking segment.

[0014] In some embodiments of the present invention, the method for preparing the blocked polyurethane oligomer comprises the following steps: S1. Mix the dehydrated diol and diisocyanate uniformly in a reactor, add an organotin catalyst accounting for 0.01%-0.1% of the total weight of N,N-dihydroxyethyl oxamide and diisocyanate, and keep the reaction at a constant temperature of 50-80°C for 2-4 h under a nitrogen atmosphere to obtain an isocyanate prepolymer; S2. Lower the reaction temperature to 50°C, slowly drop 2-(tert-butylamino)ethyl methacrylate into the above isocyanate prepolymer, and add 4-methoxyphenol, and continue the constant temperature reaction for 4-6 h to obtain a blocked polyurethane oligomer.

[0015] In some embodiments of the present invention, the diol is one or more of polycaprolactone diol with a molecular weight of 500-2000, polytetrahydrofuran ether diol with a molecular weight of 1000-3000, and polyethylene glycol with a molecular weight of 1000-3000; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate; the organotin catalyst is dibutyltin dilaurate.

[0016] In some embodiments of the present invention, the reactive diluent is one or more of acryloylmorpholine, 2-hydroxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, N,N-dimethylacrylamide, or 1,6-hexanediol dimethacrylate; the photoinitiator is one or more of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0017] The second aspect of the present invention provides a method for preparing the photothermal dual-curing resin composition described in the first aspect. By mass percentage: 40-70% of the blocked polyurethane oligomer, 30-50% of the reactive diluent, 2-15% of the diamine chain extender with multiple hydrogen bonds, and 0.5-3% of the photoinitiator. Weigh each substance and mix them evenly to obtain the photothermal dual-curing resin composition.

[0018] The third aspect of the present invention provides an application of the photothermal dual-curing resin composition in photocuring 3D printing. The photocuring 3D printing includes printing using SLA, DLP, or LCD 3D printing equipment, and performing thermal curing treatment after printing and molding. The thermal curing temperature is 90-140°C, and the thermal curing time is 1-8 h.

[0019] The use of the photothermal dual-curing resin composition requires a dual-curing process of light and heat. Its photocuring process is the free radical polymerization of the double bonds of the blocked polyurethane oligomer and the reactive diluent; the heat-curing process is the dissociation of the urea bond in the blocked polyurethane oligomer to obtain reactive isocyanate groups, which react with the amino groups of the diamine chain extender to form polyurea, significantly improving the material properties.

[0020] Advantages of the present invention Compared with the prior art, the present invention has the following advantages: (1) By uniformly mixing a blocked polyurethane oligomer, a diamine chain extender with multiple hydrogen bonds, a reactive diluent, and a photoinitiator, the present invention obtains a photothermal dual-curing resin composition. Compared with traditional two-component photosensitive resins, the resin composition of the present invention has a low viscosity, good stability, can be stored for a long time without pre-use mixing, and its printed products have high strength and good toughness.

[0021] (2) The diamine chain extender provided by the present invention has multiple hydrogen bonds, which can significantly improve the mechanical properties of the material after heat treatment. Its advantages are as follows: on the one hand, connecting small molecule hard segments to the chain extender instead of the oligomer during synthesis can avoid excessive viscosity of the oligomer due to connecting small molecule hard segments during synthesis, further reducing the overall viscosity of the resin composition, so that it can meet the printing requirements of a photocuring 3D printer at room temperature; on the other hand, commercially available small molecule diamine chain extenders (such as 4,4'-diaminodicyclohexylmethane, isophorone diamine, etc.) generally have high activity and are prone to Michael addition reaction with the double bonds in acrylate, resulting in a sharp increase in resin viscosity or even gelation, making the storage stability of the resin poor, while the diamine chain extender with multiple hydrogen bonds has low activity at room temperature and good storage stability after mixing with acrylate. Description of the drawings

[0022] Figure 1 It is a complex lattice model diagram printed with the photothermal dual-curing resin composition in Example 1 of the present invention; Figure 2 It is a tensile property test comparison diagram of Example 1, Example 7, and Example 8. Detailed implementation manners

[0023] The following examples are used here to demonstrate the preferred implementation schemes of the present invention. Those skilled in the art will understand that the technologies disclosed in the following examples represent the technologies discovered by the inventor that can be used to implement the present invention, and thus can be regarded as the preferred schemes for implementing the present invention. However, those skilled in the art should understand from this specification that many modifications can be made to the specific embodiments disclosed here, and still obtain the same or similar results without departing from the spirit or scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The materials cited herein and the materials cited by them will be incorporated by reference. Those skilled in the art will recognize or can ascertain, using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0025] A photothermal dual-curing resin composition, the raw material components and their mass percentages are as follows: Blocked polyurethane oligomer 40 - 70% Reactive diluent 30 - 50% Diamine chain extender with multiple hydrogen bonds 2 - 15% Photoinitiator 0.5 - 3%.

[0026] Among them, the structural formula of the diamine chain extender with multiple hydrogen bonds is as follows:

[0027] Among them, "R1" represents an isocyanate linking segment; "R2" represents a diacylhydrazide linking segment.

[0028] The structural formula of the blocked polyurethane oligomer is as follows:

[0029] Among them, " " represents a diol linking segment; "R" represents an isocyanate linking segment.

[0030] The reactive diluent is one or more of morpholine acrylate, 2-hydroxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, N,N-dimethylacrylamide, or 1,6-hexanediol dimethacrylate; the photoinitiator is one or more of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0031] The technical solutions of the present application will be further described in detail below in conjunction with specific embodiments.

[0032] Example 1 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) 500 g of dehydrated polycaprolactone diol (PCL, M n2000) was mixed uniformly with 111.15 g of isophorone diisocyanate (IPDI) in a reactor. After adding 0.01 g of dibutyltin dilaurate (DBTDL), the reaction was placed under a nitrogen atmosphere and kept at 80 °C for 4 h to obtain an isocyanate prepolymer; The reaction temperature was lowered to 50 °C, 91.65 g of 2-(tert-butylamino)ethyl methacrylate (TBAEMA) was slowly added dropwise to the above isocyanate prepolymer, and 0.21 g of 4-methoxyphenol (MEHQ) was added. The reaction was continued under constant temperature for 6 h to finally obtain the blocked polyurethane oligomer IPDI-PCL2000.

[0033] (2) Preparation of a diamine chain extender with multiple hydrogen bonds (IPDI-ADH) 1.76 g of N,N-dihydroxyethyl oxamide (BHO), 4.45 g of isophorone diisocyanate (IPDI) and 30 mL of N,N-dimethylformamide (DMF) were weighed and placed in a reactor and mixed uniformly. After adding 0.002 g of DBTDL, the reaction was placed under a nitrogen atmosphere and kept at 80 °C for 4 h to obtain an isocyanate intermediate.

[0034] The above isocyanate intermediate was slowly added dropwise to a reactor containing 3.48 g of adipic dihydrazide and 80 mL of DMF. The system was kept at 150 °C under a nitrogen atmosphere for 4 h. After removing the solvent, the diamine chain extender IPDI-ADH with multiple hydrogen bonds was finally obtained.

[0035] (3) Preparation of a photo-thermal dual-curing resin composition The above blocked polyurethane oligomer IPDI-PCL2000, the diamine chain extender IPDI-ADH with multiple hydrogen bonds, N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were weighed according to the amounts used in Table 1 and then mixed uniformly to obtain a photo-thermal dual-curing resin composition.

[0036] The photo-thermal dual-curing resin composition obtained in Example 1 was placed in a photocuring 3D printer and cured layer by layer to form a three-dimensional product; after cleaning the residual resin on the surface of the three-dimensional product with alcohol, it was transferred to a constant temperature oven at 110 °C and heat-treated for 6 h to obtain the final product, as Figure 1 shown; the product was tested for tensile strength, elongation at break, etc., and the results are shown in Table 1.

[0037] Table 1 Raw materials, ratios and test results of tensile strength and elongation at break of the product in Example 1

[0038] Example 2 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0039] (2) Preparation of diamine chain extender with multiple hydrogen bonds (IPDI-PDH) Weigh 1.76 g of N,N-dihydroxyethyl oxamide (BHO), 4.45 g of isophorone diisocyanate (IPDI) and 30 mL of N,N-dimethylformamide (DMF) and place them in a reactor to mix evenly. After adding 0.002 g of DBTDL, place the reaction in a nitrogen atmosphere at 80 °C for 4 h to obtain an isocyanate intermediate.

[0040] Slowly add the above isocyanate intermediate dropwise to a reactor containing 3.88 g of isophthalic dihydrazide and 80 mL of DMF. Place this system in a nitrogen atmosphere at 150 °C for 4 h. After removing the solvent, finally obtain the diamine chain extender IPDI-PDH with multiple hydrogen bonds.

[0041] (3) Preparation of photothermal dual-curing resin composition Weigh the above blocked polyurethane oligomer IPDI-PCL2000, diamine chain extender with multiple hydrogen bonds IPDI-PDH, N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) according to the dosages in Table 2, and then mix them evenly to obtain a photothermal dual-curing resin composition.

[0042] Place the photothermal dual-curing resin composition obtained in Example 2 in a photocuring 3D printer and cure it layer by layer to form a three-dimensional product. After cleaning the residual resin on the surface of the three-dimensional product with alcohol, transfer it to a constant temperature oven at 110 °C for heat treatment for 6 h to obtain the final product. Test the tensile strength, elongation at break, etc. of the product, and the results are shown in Table 2.

[0043] Table 2 Test results of raw materials, ratios and tensile strength and elongation at break of products in Example 2

[0044] Example 3 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0045] (2) Preparation of diamine chain extender with multiple hydrogen bonds (HDI-ADH) Weigh 1.76 g of N,N - dihydroxyethyl oxamide (BHO), 3.37 g of hexamethylene diisocyanate (HDI) and 30 mL of N,N - dimethylformamide (DMF) and place them in a reactor to mix evenly. After adding 0.002 g of DBTDL, place the reaction under a nitrogen atmosphere at 80 °C for 4 h to obtain an isocyanate intermediate.

[0046] Slowly add the above - mentioned isocyanate intermediate dropwise to a reactor containing 3.48 g of adipic dihydrazide and 80 mL of DMF. Place this system under a nitrogen atmosphere at 150 °C for 4 h. After removing the solvent, finally obtain the diamine chain extender HDI - ADH with multiple hydrogen bonds.

[0047] (3)Preparation of a photo - thermal dual - curing resin composition Weigh the above - mentioned blocked polyurethane oligomer IPDI - PCL2000, the diamine chain extender HDI - ADH with multiple hydrogen bonds, N,N - dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6 - trimethylbenzoyl diphenylphosphine oxide (TPO) according to the amounts used in Table 3, and then mix them evenly to obtain a photo - thermal dual - curing resin composition.

[0048] Place the photo - thermal dual - curing resin composition obtained in Example 3 into a photocuring 3D printer for layer - by - layer curing and forming to obtain a three - dimensional product. After cleaning the residual resin on the surface of the three - dimensional product with alcohol, transfer it to a constant - temperature oven at 110 °C for heat treatment for 6 h to obtain the final product. Test the tensile strength, elongation at break, etc. of the product, and the results are shown in Table 3.

[0049] Table 3 Test results of raw materials, ratios and tensile strength, elongation at break of the product in Example 3

[0050] Example 4 (1)Preparation of a blocked polyurethane oligomer (IPDI - PCL2000) The preparation method of the blocked polyurethane oligomer IPDI - PCL2000 is the same as that in Example 1.

[0051] (2)Preparation of a diamine chain extender with multiple hydrogen bonds (HDI - PDH) Weigh 1.76 g of N,N - dihydroxyethyl oxamide (BHO), 3.37 g of hexamethylene diisocyanate (HDI) and 30 mL of N,N - dimethylformamide (DMF) and place them in a reactor to mix evenly. After adding 0.002 g of DBTDL, place the reaction under a nitrogen atmosphere at 80 °C for 4 h to obtain an isocyanate intermediate.

[0052] The above isocyanate intermediate was slowly added dropwise to a reactor containing 3.88 g of isophthalic dihydrazide and 80 mL of DMF. The system was maintained at a constant temperature of 150 °C in a nitrogen atmosphere for 4 h. After removing the solvent, the diamine chain extender HDI-PDH with multiple hydrogen bonds was finally obtained.

[0053] (3)Preparation of the photo-thermal dual-curing resin composition The above blocked polyurethane oligomer IPDI-PCL2000, the diamine chain extender HDI-PDH with multiple hydrogen bonds, N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA), and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were weighed according to the amounts in Table 4 and then mixed evenly to obtain the photo-thermal dual-curing resin composition.

[0054] The photo-thermal dual-curing resin composition obtained in Example 4 was placed in a photocuring 3D printer and cured layer by layer to form a three-dimensional article. After cleaning the residual resin on the surface of the three-dimensional article with alcohol, it was transferred to a constant temperature oven at 110 °C for heat treatment for 6 h to obtain the final product. The product was tested for tensile strength, elongation at break, etc., and the results are shown in Table 4.

[0055] Table 4 Test results of raw materials, ratios, tensile strength, and elongation at break of the product in Example 4

[0056] Example 5 (1)Preparation of the blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0057] (2)Preparation of the diamine chain extender with multiple hydrogen bonds (HMDI-ADH) 1.76 g of N,N-dihydroxyethyl oxamide (BHO), 5.26 g of dicyclohexylmethane diisocyanate (HMDI), and 30 mL of N,N-dimethylformamide (DMF) were weighed and placed in a reactor and mixed evenly. After adding 0.002 g of DBTDL, the reaction was carried out at a constant temperature of 80 °C in a nitrogen atmosphere for 4 h to obtain an isocyanate intermediate.

[0058] The above isocyanate intermediate was slowly added dropwise to a reactor containing 3.48 g of adipic dihydrazide and 80 mL of DMF. The system was maintained at a constant temperature of 150 °C in a nitrogen atmosphere for 4 h. After removing the solvent, the diamine chain extender HMDI-ADH with multiple hydrogen bonds was finally obtained.

[0059] (3)Preparation of the photo-thermal dual-curing resin composition The above-mentioned blocked polyurethane oligomer IPDI-PCL2000, diamine chain extender HMDI-ADH with multiple hydrogen bonds, N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were weighed according to the amounts in Table 5 and then mixed evenly to obtain a photo-thermal dual-curing resin composition.

[0060] The photo-thermal dual-curing resin composition obtained in Example 5 was placed in a photocuring 3D printer and cured layer by layer to form a three-dimensional article. After cleaning the residual resin on the surface of the three-dimensional article with alcohol, it was transferred to a constant-temperature oven at 110 °C for heat treatment for 6 h to obtain the final product. The product was tested for tensile strength, elongation at break, etc., and the results are shown in Table 5.

[0061] Table 5 Test results of raw materials, ratios and tensile strength, elongation at break of the product in Example 5

[0062] Example 6 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0063] (2) Preparation of diamine chain extender with multiple hydrogen bonds (HMDI-PDH) Weigh 1.76 g of N,N-dihydroxyethyl oxamide (BHO), 5.26 g of dicyclohexylmethane diisocyanate (HMDI) and 30 mL of N,N-dimethylformamide (DMF) and place them in a reactor and mix evenly. After adding 0.002 g of DBTDL, the reaction is placed under a nitrogen atmosphere at 80 °C for 4 h to obtain an isocyanate intermediate.

[0064] The above isocyanate intermediate was slowly added dropwise to a reactor containing 3.88 g of isophthalic dihydrazide and 80 mL of DMF. The system was placed under a nitrogen atmosphere at 150 °C for 4 h. After removing the solvent, the diamine chain extender HMDI-PDH with multiple hydrogen bonds was finally obtained.

[0065] (3) Preparation of photo-thermal dual-curing resin composition The above-mentioned blocked polyurethane oligomer IPDI-PCL2000, diamine chain extender HMDI-PDH with multiple hydrogen bonds, N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) were weighed according to the amounts in Table 6 and then mixed evenly to obtain a photo-thermal dual-curing resin composition.

[0066] The obtained photo-thermal dual-curing resin composition in Example 6 was placed in a photo-curing 3D printer and cured layer by layer to form a three-dimensional article; after cleaning the residual resin on the surface of the three-dimensional article with alcohol, it was transferred to a constant-temperature oven at 110 °C for heat treatment for 6 h to obtain the final product; the tensile strength, elongation at break, etc. of the product were tested, and the results are shown in Table 6.

[0067] Table 6 Test results of raw materials, ratios, tensile strength, and elongation at break of the product in Example 6

[0068] Example 7 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0069] (2) Preparation of photo-thermal dual-curing resin composition After weighing the above-mentioned blocked polyurethane oligomer IPDI-PCL2000, 4,4'-diaminodicyclohexylmethane (PACM), N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA), and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) according to the amounts shown in Table 7, they were mixed evenly to obtain a photo-thermal dual-curing resin composition.

[0070] The obtained photo-thermal dual-curing resin composition in Example 7 was placed in a photo-curing 3D printer and cured layer by layer to form a three-dimensional article; after cleaning the residual resin on the surface of the three-dimensional article with alcohol, it was transferred to a constant-temperature oven at 110 °C for heat treatment for 6 h to obtain the final product; the tensile strength, elongation at break, etc. of the product were tested, and the results are shown in Table 7.

[0071] Table 7 Test results of raw materials, ratios, tensile strength, and elongation at break of the product in Example 7

[0072] Example 8 (1) Preparation of blocked polyurethane oligomer (IPDI-PCL2000) The preparation method of the blocked polyurethane oligomer IPDI-PCL2000 is the same as that in Example 1.

[0073] (2) Preparation of photo-thermal dual-curing resin composition Weigh the above-mentioned closed polyurethane oligomer IPDI-PCL2000, isophorone diamine (IPDA), N,N-dimethylacrylamide (DMAA), isobornyl acrylate (IBOA) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) according to the dosages in Table 8, and then mix them evenly to obtain a photo-thermal dual-curing resin composition.

[0074] Place the photo-thermal dual-curing resin composition obtained in Example 8 in a photo-curing 3D printer and cure it layer by layer to form a three-dimensional product; after cleaning the residual resin on the surface of the three-dimensional product with alcohol, transfer it to a constant-temperature oven at 110 °C for heat treatment for 6 h to obtain the final product; test the tensile strength, elongation at break, etc. of the product, and the results are shown in Table 8.

[0075] Table 8 Test results of raw materials, ratios, tensile strength and elongation at break of Example 8

[0076] The results show that: in Examples 1-6, the photo-thermal dual-curing resin composition prepared by the scheme of the present application uses a diamine chain extender with multiple hydrogen bonds, and the viscosity change range of the mixture and the viscosity after 24 h is 17.8%-23%, showing low room-temperature activity and good storage stability; while in Examples 7 and 8, using common chain extenders such as 4,4'-diaminodicyclohexylmethane (PACM) and isophorone diamine (IPDA), the viscosity change range of the mixture and the viscosity after 24 h is 1352.1%-1454.1%, showing poor stability, unable to be stored, and can only be prepared and used immediately.

[0077] Compare the tensile property tests of Examples 1, 7, and 8, as Figure 2 shown.

[0078] The results show that: in terms of toughness, the tensile properties of the products obtained by using common chain extenders are much lower than those of the products obtained by the scheme of the present application.

[0079] All the documents mentioned in the present invention are cited in this application as references, just as if each document is cited separately as a reference. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by this application.

Claims

1. A photothermal dual-curing resin composition, characterized in that, The raw material components contained in the photothermal dual-curing resin composition and the mass percentages of each component are as follows: Blocked polyurethane oligomer: 40 - 70% Reactive diluent: 30 - 50% Diamine chain extender with multiple hydrogen bonds: 2 - 15% Photoinitiator: 0.5 - 3%.

2. The photothermal dual-curing resin composition according to claim 1, wherein The structural formula of the diamine chain extender with multiple hydrogen bonds is as follows: Among them, "R1" represents an isocyanate linking segment; "R2" represents a diacylhydrazide linking segment.

3. The photothermal dual-curing resin composition according to claim 3, characterized in that The preparation method of the diamine chain extender with multiple hydrogen bonds includes the following steps: S1. Weigh N,N-dihydroxyethyl oxamide, diisocyanate, and an appropriate amount of solvent, place them in a reactor and mix. The molar ratio of -OH to -NCO in N,N-dihydroxyethyl oxamide and diisocyanate is 1:(1.8 - 2.2). Then add an organotin catalyst accounting for 0.01% - 0.1% of the total weight of N,N-dihydroxyethyl oxamide and diisocyanate. Keep this system at a constant temperature of 50 - 80°C in a nitrogen atmosphere for 2 - 5 h to obtain an isocyanate intermediate. S2. Slowly add the isocyanate intermediate obtained in step S1 to a reactor containing diacylhydrazide and an appropriate amount of solvent. The molar ratio of -NH2 to -NCO in diacylhydrazide and the isocyanate intermediate is 1:(1.8 - 2.2). Keep this system at a constant temperature of 90 - 150°C in a nitrogen atmosphere for 2 - 5 h, and remove the solvent to obtain the diamine chain extender with multiple hydrogen bonds.

4. The photothermal dual-curing resin composition according to claim 3, wherein The diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate; the organotin catalyst is dibutyltin dilaurate; the diacylhydrazide is one or more of malonic diacylhydrazide, succinic diacylhydrazide, glutaric diacylhydrazide, adipic diacylhydrazide, pimelic diacylhydrazide, azelaic diacylhydrazide, sebacic diacylhydrazide, isophthalic diacylhydrazide; the solvent is one or more of tetrahydrofuran, ether, toluene, acetone, N,N-dimethylformamide, N,N-dimethylacetamide.

5. The photothermal dual-curing resin composition according to claim 1, wherein The structural formula of the blocked polyurethane oligomer is as follows: Among them, " " represents a diol linking segment; "R" represents an isocyanate linking segment.

6. The photocurable resin composition according to claim 5, characterized in that, The preparation method of the blocked polyurethane oligomer includes the following steps: S1. Mix dehydrated diol and diisocyanate evenly in a reactor, add an organotin catalyst accounting for 0.01% - 0.1% of the total weight of N,N-dihydroxyethyl oxamide and diisocyanate. Keep the reaction at a constant temperature of 50 - 80°C in a nitrogen atmosphere for 2 - 4 h to obtain an isocyanate prepolymer; S2. Lower the reaction temperature to 50°C, slowly drop 2-(tert-butylamino)ethyl methacrylate into the above isocyanate prepolymer, and add 4-methoxyphenol, and continue the constant temperature reaction for 4 - 6 h to obtain a blocked polyurethane oligomer.

7. The photothermal dual-curing resin composition according to claim 6, wherein, The diol is one or more of polycaprolactone diol with a molecular weight of 500-2000, polytetrahydrofuran ether diol with a molecular weight of 1000-3000, and polyethylene glycol with a molecular weight of 1000-3000; the diisocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate; the organotin catalyst is dibutyltin dilaurate.

8. The photothermal dual-curing resin composition according to claim 1, wherein The reactive diluent is one or more of acryloylmorpholine, 2-hydroxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, N,N-dimethylacrylamide, or 1,6-hexanediol dimethacrylate; the photoinitiator is one or more of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, or 2-hydroxy-2-methyl-1-phenylpropan-1-one.

9. A method for preparing the photo-thermal dual-curing resin composition according to any one of claims 1-8, characterized in that: By mass percentage: 40-70% of blocked polyurethane oligomer, 30-50% of reactive diluent, 2-15% of diamine chain extender with multiple hydrogen bonds, and 0.5-3% of photoinitiator. Weigh each substance and mix them evenly to obtain the photo-thermal dual-curing resin composition.

10. Application of a photothermal dual-curing resin composition in photocuring 3D printing, characterized in that: The photocuring 3D printing includes printing using SLA, DLP, or LCD 3D printing equipment, and after printing and forming, performing thermal curing treatment. The thermal curing temperature is 90-140°C, and the thermal curing time is 1-8 h.

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