Photo-thermal dual-curing 3D printing ink as well as preparation method and application thereof

Abstract

The invention relates to the technical field of resin materials, in particular to photo-thermal dual-curing 3D printing ink and a preparation method and application thereof.The photo-thermal dual-curing 3D printing ink is prepared from, by weight, 30-60 parts of acrylate monomer, 10-30 parts of photoinitiator, 5-10 parts of photoinitiator, 1-5 parts of photoinitiator, 1-5 parts of photoinitiator, 1-5 parts of photoinitiator and 1-5 parts of photoinitiator. 40 to 70 parts of a reactive diluent; 3 to 10 parts of a photosensitive isocyanate monomer; and 2-5 parts of a photoinitiator. The photosensitive isocyanate monomer is introduced into the raw materials to obtain a dual-curing system, so that the 3D printing ink can be subjected to photocuring molding and then subjected to heat treatment to form an interpenetrating polymer network (IPN) structure, and the inevitable step effect in the photocuring 3D printing process is improved, so that the structural anisotropy is reduced, and the 3D printing quality is improved. The mechanical property of the material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of resin materials, and in particular to a photothermal dual-curing 3D printing ink and a preparation method and application thereof. Background Art

[0002] With the popularization of 5G technology, the emergence of the fifth generation of mobile communication technology has made fast and stable information transmission more possible. Among them, interlayer dielectric materials are one of the core components to achieve efficient transmission of high-frequency signals and low loss. Such materials need to have a low dielectric constant (D k ), low dielectric loss (D f ), high thermal stability, excellent mechanical properties and environmental resistance.

[0003] Traditional interlayer dielectric materials are mainly polymer-based low-dielectric materials, such as fluororesins; these traditional interlayer dielectric materials are usually prepared by subtractive manufacturing; with the increasing development of 5G high-frequency communications, the disadvantages of subtractive manufacturing, such as serious waste, high cost, and low efficiency, have become increasingly prominent; at the same time, 3D printing technology has advantages over traditional subtractive manufacturing methods, such as high design freedom, material savings, cost savings, and processing time savings. Therefore, introducing 3D printing technology into the preparation of interlayer dielectric materials will become a powerful driving force for the development of modern wireless communication technology.

[0004] Currently, the photosensitive resins suitable for 3D printing technology are mainly based on acrylate monomers. Although such a system has a fast curing rate, the uneven cross-linked network structure formed due to the rapid reaction process and limited curing degree leads to poor mechanical properties of the photocurable 3D printing material, which cannot meet the performance requirements of interlayer dielectric materials. Summary of the Invention

[0005] In order to solve the problem of poor mechanical properties of light-cured 3D printing materials in the prior art, the present invention provides a light-thermal dual-curing 3D printing ink, which uses acrylate monomers, reactive diluents and photosensitive isocyanate monomers as the main raw materials to prepare a 3D printing material with high thermal stability, low viscosity, low dielectric material and excellent mechanical properties, solving the problem of poor mechanical properties of light-cured 3D printing materials in the prior art.

[0006] The technical solution adopted by the present invention to solve its technical problem is: A photothermal dual-curing 3D printing ink, comprising the following components by weight: 30-60 parts of acrylate monomer; 40-70 parts of active diluent; 3-10 parts of photosensitive isocyanate monomer; 2~5 parts of photoinitiator.

[0007] Optionally, the photosensitive isocyanate monomer is prepared by the following method: under an inert gas atmosphere, hydroxypropyl acrylate is added dropwise to 2,4-toluene diisocyanate, and the reaction is carried out at 25-35 °C under light shielding conditions to obtain the photosensitive isocyanate monomer.

[0008] Optionally, the molar ratio of the hydroxypropyl acrylate to the 2,4-toluene diisocyanate is (1-1.1):1.

[0009] Optionally, the acrylate monomer is a difunctional or trifunctional acrylate monomer.

[0010] Optionally, the acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, and tris(2-hydroxyethyl) isocyanurate triacrylate.

[0011] Optionally, the active diluent is selected from at least one of isobornyl methacrylate and 4-acryloylmorpholine.

[0012] Optionally, the photoinitiator is (2,4,6-trimethylbenzoyl) diphenylphosphine oxide.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned photo-thermal dual-curing 3D printing ink, which includes the following process: under light shielding conditions, according to the formula amount, the acrylate monomer, the active diluent, the photosensitive isocyanate monomer, and the photoinitiator are mixed and stirred, and then vacuum degassed to remove bubbles to obtain the photo-thermal dual-curing 3D printing ink. Another object of the present invention is to provide an application of the above-mentioned photo-thermal dual-curing 3D printing ink in an interlayer dielectric material.

[0014] Another object of the present invention is to provide an application of the above-mentioned photo-thermal dual-curing 3D printing ink in a wave-transparent material.

[0015] The beneficial effects of the present invention are as follows: The photo-thermal dual-curing 3D printing ink provided by the present invention obtains a dual-curing system by introducing a photosensitive isocyanate monomer into the raw materials, so that the 3D printing ink can be first photocured and then heat-treated to form an interpenetrating polymer network (IPN) structure, improving the inevitable step effect in the photocuring 3D printing process, thereby reducing the structural anisotropy and improving the mechanical properties of the material; the photo-thermal dual-curing 3D printing ink uses two different processing stages to obtain a material with target properties, and the photo-thermal dual-curing polymer system provides a solution for 3D printing that can balance mechanical properties and curing speed. Description of the Drawings

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is the infrared spectrum diagram of the photosensitive isocyanate monomer prepared in Example 1 of the present invention; Figure 2 It is the viscosity performance diagram of the photosensitive isocyanate monomer prepared in Example 1 of the present invention; Figure 3 It is the glass transition temperature performance diagram of the photosensitive isocyanate monomer prepared in Example 1 of the present invention; Figure 4 It is the thermal weight loss performance diagram of the photosensitive isocyanate monomer prepared in Example 1 of the present invention; Figure 5 It is the DSC curve diagram of the photosensitive isocyanate monomer prepared in Example 1 of the present invention; Figure 6 It is the material photos of the 3D printing sample prepared in Example 1 of the present invention before and after thermal curing; Figure 7 It is the viscosity diagram of the dual-curing 3D printing ink prepared in Examples 1-6 of the present invention; Figure 8 It is the physical diagram and infrared spectrum diagram of the sample of the dual-curing 3D printing ink prepared in Example 1 of the present invention before and after photo-curing printing and after heat treatment; Figure 9 It is the mechanical property diagram of the 3D printing sample prepared in Examples 1-6 of the present invention after thermal curing; Figure 10 It is the glass transition temperature performance diagram of the 3D printing sample prepared in Examples 1-6 of the present invention after thermal curing; Figure 11 It is the dielectric constant and loss performance diagram of the 3D printing sample prepared in Examples 1-6 of the present invention after thermal curing. Detailed Embodiments

[0018] The present invention will now be described in further detail. The following described embodiments are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0019] To solve the problem of poor mechanical properties of the photo-curing 3D printing materials in the prior art, the present invention provides a photo-thermal dual-curing 3D printing ink. Calculated by weight parts, the raw materials include the following components: Acrylate monomer 30-60 parts; Active diluent 40-70 parts; Photosensitive isocyanate monomer 3-10 parts; 2 to 5 parts of photoinitiator.

[0020] The photothermal dual-curing 3D printing ink provided by the present invention obtains a dual-curing system by introducing a photosensitive isocyanate monomer into the raw materials, enabling the 3D printing ink to be first photocured and then heat-treated to form an interpenetrating polymer network (IPN) structure, improving the inevitable step effect in the photocuring 3D printing process, thereby reducing the structural anisotropy and improving the mechanical properties of the material; the photothermal dual-curing 3D printing ink utilizes two different processing stages to obtain a material with target properties, and the photothermal dual-curing polymer system provides a solution for 3D printing that can balance mechanical properties and curing speed.

[0021] Specifically, the present invention preferably prepares the photosensitive isocyanate monomer according to the following method: under an inert gas environment, dropwise add hydroxypropyl acrylate (HPA) to 2,4-toluene diisocyanate (TDI), and react at 25-35 °C under light-shielded conditions to obtain the photosensitive isocyanate monomer (TH).

[0022] The present invention conducts the reaction by a direct dropwise addition method. During the synthesis process, among the two isocyanate groups (-NCO) of TDI, due to the steric hindrance effect, the isocyanate group at the 4-position first reacts with the hydroxyl group of HPA, while the isocyanate group at the 2-position has a lower activity and no catalyst is added to promote the reaction, so the -NCO at the 2-position does not participate in the reaction, thereby obtaining a photosensitive isocyanate monomer with an isocyanate group, enabling the photosensitive isocyanate monomer to be first photocured and then post-cured by heat treatment to obtain a photo-thermal dual-curing system.

[0023] Introducing the photosensitive isocyanate monomer provided by the present invention can avoid the problem of uneven distribution of the printing material caused by the inability of conventional thermal curing monomers to participate in the photocuring reaction first during 3D printing, thereby improving the mechanical properties of the printing material. Moreover, the isocyanate group can self-polymerize at high temperature to form a six-membered heterocyclic structure with isocyanurate as the core, and the symmetric triazine ring structure also endows it with properties such as high thermal stability and low dielectric constant, so that while improving the mechanical properties of the printing material, its dielectric properties and high thermal stability can be improved, enabling it to meet the performance requirements of interlayer dielectric materials, wave-transparent materials, etc.

[0024] Furthermore, the present invention preferably uses a molar ratio of hydroxypropyl acrylate to 2,4-toluene diisocyanate of (1-1.1):1, so as to enable one isocyanate group in 2,4-toluene diisocyanate to react with hydroxypropyl acrylate to generate a double bond by controlling the amount of raw materials, thereby enabling the synthesized monomer to be first photocured and then post-cured by heat treatment.

[0025] The photo-thermal dual-curing reaction is a strategy for obtaining materials using two different processing stages. First, photo-curing is carried out to form a shape, and then heat treatment is performed to form an interpenetrating polymer network (IPN) structure, which improves various properties of the material and reduces problems such as a large thermal expansion coefficient and poor mechanical properties of photo-cured 3D printing materials caused by the uneven cross-linked network structure resulting from the photo-curing reaction.

[0026] To balance the curing speed and mechanical properties of 3D printing materials, the present invention preferably uses acrylate monomers as difunctional or trifunctional acrylate monomers, and further preferably selects the acrylate monomer from at least one of 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), tricyclodecane dimethanol diacrylate (TCDDA), and tris(2-hydroxyethyl) isocyanurate triacrylate (THEICTA). Among them, the structural formula of HDDA is shown as follows: ; The structural formula of TPGDA is shown as follows: ; The structural formula of TCDDA is shown as follows: ; The structural formula of THEICTA is shown as follows: .

[0027] The present invention preferably selects the reactive diluent from at least one of isobornyl methacrylate (IBOMA) and 4-acryloylmorpholine (ACMO). Among them, the structural formula of IBOMA is shown as follows: ; The structural formula of ACMO is shown as follows: .

[0028] The present invention preferably uses (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO) as the photoinitiator.

[0029] The photo-thermal dual-curing 3D printing ink provided by the present invention uses acrylate monomers, reactive diluents, and self-synthesized photosensitive isocyanate monomers as the main raw materials to prepare a material with high thermal stability, low viscosity, and low dielectric constant, and further optimizes the temperature resistance and dielectric properties by adjusting the types of acrylate monomers and reactive diluents.

[0030] The photo-thermal dual-curing 3D printing ink provided by the present invention can prepare 3D printing samples according to the following method: ① Use a DLP 3D printer (M5s pro, Anycubic) to build a PSPI special-shaped three-dimensional structure layer by layer. The thickness of each layer is 50 or 100 µm. The 3D model is first built by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then sliced into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.). ② Optimize the printing parameters, that is, the layer thickness is 50 µm and the exposure time for each layer is 30 s, to build the 3D structure. ③ After printing, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol. ④ Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, and 220 °C / 30 min under a nitrogen atmosphere, and naturally cool to room temperature to obtain the final 3D printed sample.

[0031] Another object of the present invention is to provide a method for preparing the above-mentioned photothermal dual-curing 3D printing ink, which includes the following process: under light-shielded conditions, according to the formula amount, mix and stir acrylate monomer, active diluent, photosensitive isocyanate monomer, and photoinitiator, and then perform vacuum degassing to remove bubbles to obtain the photothermal dual-curing 3D printing ink.

[0032] The method for preparing the photothermal dual-curing 3D printing ink provided by the present invention has a simple process and is easy to operate; the prepared photothermal dual-curing 3D printing ink obtains a dual-curing system by introducing a photosensitive isocyanate monomer into the raw materials, enabling the 3D printing ink to be first photocured and then heat-treated to form an interpenetrating polymer network (IPN) structure, improving the inevitable step effect in the photocuring 3D printing process, thereby reducing the structural anisotropy and improving the mechanical properties of the material; the photothermal dual-curing 3D printing ink utilizes two different processing stages to obtain a material with target properties, and the dual-curing polymer system provides a solution for 3D printing that can balance mechanical properties and curing speed.

[0033] Another object of the present invention is to provide an application of the above-mentioned photothermal dual-curing 3D printing ink in interlayer dielectric materials.

[0034] Another object of the present invention is to provide an application of the above-mentioned photothermal dual-curing 3D printing ink in wave-transparent materials.

[0035] The photothermal dual-curing 3D printing ink provided by the present invention obtains a dual-curing system by introducing a photosensitive isocyanate monomer into the raw materials. A high thermal stability, low viscosity, and low dielectric material is prepared using acrylate monomers, active diluents, and the self-synthesized photosensitive isocyanate monomer as the main raw materials. This material can meet the performance requirements of interlayer dielectric materials, wave-transparent materials, etc.

[0036] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the accompanying drawings.

[0037] Example 1 This example provides a preparation method for a photothermal dual-curing 3D printing ink, including the steps: S1: Prepare the photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4-toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Subsequently, slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare the photothermal dual-curing 3D printing ink: Under dark conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, degas under vacuum for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain the dual-curing 3D printing ink (denoted as photothermal dual-curing No. 1 ink); By weight, the raw materials include the following components: 1,6-Hexanediol dipropionate (HDDA) 45 parts; 4-Acryloylmorpholine (ACMO) 45 parts; Photosensitive isocyanate monomer 6 parts; (2,4,6-Trimethylbenzoyl) diphenylphosphine oxide (TPO) 4 parts.

[0038] S3: Prepare 3D printing samples S31: Use the photothermal dual-curing 3D printing ink and a DLP 3D printer (M5s pro, Anycubic) to layer by layer construct a special-shaped three-dimensional structure; the thickness of each layer is 50 µm; the 3D model is first constructed by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, i.e., the layer thickness is 50 µm, the exposure time for each layer is 30 s, and build the 3D structure; S33: After printing is completed, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, and 220 °C / 30 min under a nitrogen atmosphere, and then naturally cool to room temperature to obtain the final 3D printed sample.

[0039] See Figure 1 As shown, in the infrared spectrum of the photosensitive isocyanate monomer prepared in this example, the -NH peak at 3335 cm -1 and the C=O peak at 1715 cm -1 can verify the successful synthesis of the photosensitive isocyanate monomer; See Figure 2 As shown, the viscosity of the photosensitive isocyanate monomer is about 500 mPa·s, and the viscosity is relatively large; See Figure 3 As shown, the glass transition temperature of the photosensitive isocyanate monomer is 181 °C; Through Figure 3 , Figure 4 it is proved that it has high thermal stability; See Figure 5 As shown, the photosensitive isocyanate monomer has a relatively intense exothermic peak at 150 °C - 160 °C, proving that it undergoes intense curing in this temperature range.

[0040] See Figure 6 As shown, comparing the volume of the 3D printing material before and after thermal curing, there is no obvious shrinkage.

[0041] Example 2 This example provides a preparation method of a photo-thermal dual-curing 3D printing ink, including the steps: S1: Prepare the photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4-toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Subsequently, slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction is completed, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare the photo-thermal dual-curing 3D printing ink: Under light-shielding conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, vacuum degas for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain the photo-thermal dual-curing 3D printing ink (denoted as photo-thermal dual-curing No. 2 ink); By weight, the raw materials include the following components: 45 parts of tris(2-hydroxyethyl)isocyanuric acid triacrylate (THEICTA); 45 parts of 4-acryloylmorpholine (ACMO); 6 parts of photosensitive isocyanate monomer; 4 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO).

[0042] S3: Prepare 3D printed samples S31: Use a dual-photothermal curing 3D printing ink and a DLP 3D printer (M5s pro, Anycubic) to construct a special-shaped three-dimensional structure layer by layer; the thickness of each layer is 50 µm; the 3D model is first constructed by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, that is, the layer thickness is 50 µm, and the exposure time for each layer is 30 s, to construct a 3D structure; S33: After printing, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, and 220 °C / 30 min under a nitrogen atmosphere, and then naturally cool to room temperature to obtain the final 3D printed sample.

[0043] Example 3 This example provides a method for preparing a dual-photothermal curing 3D printing ink, including the steps: S1: Prepare photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4-toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Then slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare dual-photothermal curing 3D printing ink: Under light-shielded conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, degas under vacuum for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain a dual-photothermal curing 3D printing ink (denoted as dual-photothermal curing No. 3 ink); According to the weight parts, the raw materials include the following components: 45 parts of tripropylene glycol diacrylate (TPGDA); 45 parts of 4 - acryloylmorpholine (ACMO); 6 parts of photosensitive isocyanate monomer; 4 parts of (2,4,6 - trimethylbenzoyl) diphenylphosphine oxide (TPO).

[0044] S3: Prepare 3D printed samples S31: Using a dual - curing 3D printing ink, use a DLP 3D printer (M5s pro, Anycubic) to build a special - shaped three - dimensional structure layer by layer; the thickness of each layer is 50 µm; the 3D model is first built by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (ProgramPhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, that is, the layer thickness is 50 µm, the exposure time for each layer is 30 s, and build the 3D structure; S33: After printing, take out the 3D sample from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, 220 °C / 30 min under a nitrogen atmosphere, and naturally cool to room temperature to obtain the final 3D printed sample.

[0045] Example 4 This example provides a preparation method of a photo - thermal dual - curing 3D printing ink, including the steps: S1: Prepare photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4 - toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Then slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare photo - thermal dual - curing 3D printing ink: Under light - shielding conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, vacuum degas for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain a photo - thermal dual - curing 3D printing ink (denoted as photo - thermal dual - curing No. 4 ink); According to weight parts, the raw materials include the following components: 45 parts of tricyclodecane dimethanol diacrylate (TCDDA); 45 parts of 4 - acryloylmorpholine (ACMO); 6 parts of photosensitive isocyanate monomer; 4 parts of (2,4,6 - trimethylbenzoyl) diphenylphosphine oxide (TPO).

[0046] S3: Prepare 3D printed samples: S31: Use the photothermal dual - curing 3D printing ink and a DLP 3D printer (M5s pro, Anycubic) to construct a special - shaped three - dimensional structure layer by layer; the thickness of each layer is 50 µm; the 3D model is first constructed by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, that is, the layer thickness is 50 µm, the exposure time for each layer is 30 s, and construct the 3D structure; S33: After printing, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, 220 °C / 30 min under a nitrogen atmosphere, and naturally cool to room temperature to obtain the final 3D printed sample.

[0047] Example 5 This example provides a preparation method of a photothermal dual - curing 3D printing ink, including the steps: S1: Prepare photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4 - toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Then slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare photothermal dual - curing 3D printing ink: Under dark conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, degas under vacuum for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain the photothermal dual - curing 3D printing ink (denoted as photothermal dual - curing No. 5 ink); According to parts by weight, the raw materials include the following components: 45 parts of tricyclodecane dimethanol diacrylate (TCDDA); 45 parts of isobornyl methacrylate (IBOMA); 6 parts of photosensitive isocyanate monomer; (2,4,6-Trimethylbenzoyl) diphenylphosphine oxide (TPO) 4 parts.

[0048] S3: Prepare 3D printed samples: S31: Use the photothermal dual-curing 3D printing ink and a DLP 3D printer (M5s pro, Anycubic) to build a special-shaped three-dimensional structure layer by layer; the thickness of each layer is 50 µm; the 3D model is first built by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, that is, the layer thickness is 50 µm, the exposure time for each layer is 30 s, and build the 3D structure; S33: After printing, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, 220 °C / 30 min under a nitrogen atmosphere, and naturally cool to room temperature to obtain the final 3D printed sample.

[0049] Example 6 This example provides a preparation method of a photothermal dual-curing 3D printing ink, including the steps: S1: Prepare photosensitive isocyanate monomer: S11: Drop 0.16 mol of 2,4-toluene diisocyanate (TDI) into a flask under a nitrogen atmosphere; S12: Then slowly drop 0.17 mol of hydroxypropyl acrylate (HPA) into it and stir in the dark at 30 °C for 3 h; S13: After the reaction, obtain the photosensitive isocyanate monomer and store it sealed; S2: Prepare photothermal dual-curing 3D printing ink: Under light-shielding conditions, according to the formula amount, mix the raw materials and stir vigorously for 1 h, vacuum degas for 5 min, and finally ultrasonicate for 5 min to remove bubbles to obtain the photothermal dual-curing 3D printing ink (denoted as photothermal dual-curing No. 6 ink); According to the weight parts, the raw materials include the following components: 45 parts of tris(2-hydroxyethyl) isocyanurate triacrylate (THEICTA); 45 parts of isobornyl methacrylate (IBOMA); 6 parts of photosensitive isocyanate monomer; 4 parts of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO).

[0050] S3: Prepare 3D printed samples: S31: Use the photothermal dual-curing 3D printing ink and a DLP 3D printer (M5s pro, Anycubic) to build a special-shaped three-dimensional structure layer by layer; the thickness of each layer is 50 µm; the 3D model is first built by 3D Studio Max software (Autodesk Inventor, American) in STL file format, and then cut into a series of 2D layers by 3D Creator Slicer software (Program PhotonWorkShop 3D Ltd.); S32: Optimize the printing parameters, that is, the layer thickness is 50 µm, the exposure time for each layer is 30 s, and build the 3D structure; S33: After printing, take out the 3D spline from the 3D printer and wash away the residual ink with ethanol; S34: Put the sample into a vacuum tube furnace and perform heat treatment at 180 °C / 120 min, 200 °C / 60 min, and 220 °C / 30 min under a nitrogen atmosphere, and naturally cool to room temperature to obtain the final 3D printed sample.

[0051] See Figure 7 As shown, it can be seen from the figure that the viscosities of the 6 groups of inks after adding 6 wt% photosensitive isocyanate monomer still remain at a low level. Among them, the relative viscosities of ink No. 2 and ink No. 6 are relatively high, but they do not exceed 100 mPa·s; See Figure 8 As shown, it can be seen from the infrared spectrogram that there are obvious changes mainly at 810 cm -1 before and after DLP, which proves the conversion of the C=C double bond; by comparing before and after thermal curing, it can be found that the N=C=O peak near 2250 cm -1 disappears, and the C=O peak at 1750 cm -1 increases, which proves that its group has been transformed into a symmetric triazine ring structure.

[0052] See Figure 9 As shown, it can be seen from the figure that after adding 6 wt% photosensitive isocyanate monomer, the mechanical properties of ink No. 2 and ink No. 6 are relatively better than those of other inks. The reason is that the trifunctional acrylate monomers used in ink No. 2 and ink No. 6 have a higher crosslinking density after polymerization. At the same time, after heat treatment, an IPN structure is formed in the system, further improving the mechanical properties of the material.

[0053] Among them, the mechanical properties in the present invention are tested according to the following methods or standards: The test is carried out with reference to "GB / T 1040.2-2022 Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics".

[0054] (1) The test shall be carried out in the same environment as the specimen conditioning, unless otherwise specified by the relevant parties.

[0055] (2) Measure the width b and thickness h within 5 mm from each end of the gauge length in the middle of each specimen: the width b is accurate to 0.01 mm, and the thickness h is accurate to 0.02 mm. Record the maximum and minimum values of the width and thickness of each specimen, and ensure that they are within the tolerance range of the corresponding material standard. Calculate the arithmetic mean of the width and thickness of each specimen for use in other calculations.

[0056] (3) Place the specimen in the fixture, and make sure that the long axis of the specimen is in a straight line with the axis of the testing machine.

[0057] (4) Record the load borne by the specimen during the test and the increment of the distance between the gauge marks or between the fixtures corresponding thereto.

[0058] See Figure 10 As shown, it can be seen from the figure that after adding 6 wt% of the photosensitive isocyanate monomer, the mechanical properties of No. 2 and No. 6 inks are relatively more excellent than those of other groups. The reason is that the trifunctional acrylate monomer used in these two groups has a relatively high crosslinking density after polymerization, and at the same time, this monomer has a nitrogen-containing triazine ring structure, which is very stable and endows the THEICTA molecule with excellent thermal stability and chemical stability. After heat treatment, an IPN structure is formed in the system, further increasing the overall crosslinking density of the material, and thus increasing the glass transition temperature of the material.

[0059] See Figure 11 As shown, it can be observed that the dielectric constants of No. 1-6 inks are all less than 3.2 and the dielectric losses are less than 0.025, which proves that No. 1-6 inks have low dielectric properties and can meet the usage requirements in various fields. The reason for the low dielectric properties of the inks can be attributed to the low-dielectric triazine ring structure formed by the isocyanate groups after the thermal curing of the photosensitive isocyanate monomer; due to the high-temperature resistance, low dielectric and high mechanical properties of the inks in the examples, they can be applied to fields such as radar radomes. The following comparative examples are all compared with Example 2.

[0060] Comparative Example 1 The difference between this comparative example and Example 2 is that the photosensitive isocyanate monomer was prepared as follows: 2,4-toluene diisocyanate (TDI) and hydroquinone (the amount used was 0.15% of the mass of TDI) were added to a reaction flask, and dibutyltin dilaurate (DBTDL) was used as a catalyst. A mixed solution formed by dissolving hydroxypropyl acrylate in acetone was added dropwise with stirring. The molar amount of hydroxypropyl acrylate was equal to that of TDI, and the reaction was carried out at 45 °C for 3 h to obtain a semi-blocked isocyanate TDI-HPA monomer.

[0061] The ink prepared from the photosensitive isocyanate monomer (TDI-HPA) in this comparative example was used to prepare samples by 3D printing for mechanical testing, glass transition temperature testing, and thermogravimetric testing. The test results are shown in Table 1 below. Comparing with Example 2, it can be seen that Example 2 has higher mechanical properties and temperature resistance while having a more convenient synthesis method.

[0062] Table 1 Performance test results of Example 2 and Comparative Example 1 Tensile strength (MPa) Glass transition temperature (°C) Thermogravimetric temperature (°C) Comparative Example 1 60 178 277 Example 2 80 215 298 Comparative Example 2 The difference between this comparative example and Example 2 is that a hexafunctional dipentaerythritol hexaacrylate was used as the acrylate monomer to prepare the 3D printing ink, and the other conditions were the same as those in Example 2. After the printing ink prepared in this comparative example was tested for its viscosity, samples were prepared by 3D printing under the same curing time to test the mechanical properties. The test results are shown in Table 2 below. Comparing with the data of Example 2, it can be seen that since this comparative example uses a high-functional acrylate monomer, its mechanical properties are slightly higher than those of Example 2, but the high crosslinking density also causes a significant reduction in the elongation at break. Example 2 has a tensile strength comparable to that of the high-functional acrylate monomer under the conditions of lower viscosity and higher elongation at break.

[0063] Table 2 Performance test results of Example 2 and Comparative Example 2 Tensile strength (MPa) Elongation at break (%) Viscosity (mpa·s) Comparative Example 1 88 2.1 758 Example 2 80 3.9 98 Inspired by the above ideal embodiments of the present invention, through the above description, relevant staff can make various changes and modifications completely within the scope not deviating from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A photothermal dual-curing 3D printing ink, characterized in that By weight parts, the raw materials include the following components: 30 - 60 parts of acrylate monomer; 40 - 70 parts of reactive diluent; 3 - 10 parts of photosensitive isocyanate monomer; 2 - 5 parts of photoinitiator.

2. The dual photo-thermal curing 3D printing ink according to claim 1, characterized in that, The photosensitive isocyanate monomer is prepared by the following method: Under an inert gas environment, hydroxypropyl acrylate is added dropwise to 2,4 - tolylene diisocyanate, and the reaction is carried out at 25 - 35 °C under light - shielding conditions to obtain the photosensitive isocyanate monomer.

3. The photothermal dual-curing 3D printing ink according to claim 2, wherein The molar ratio of the hydroxypropyl acrylate to the 2,4 - tolylene diisocyanate is (1 - 1.1):

1.

4. The photothermal dual-curing 3D printing ink according to any one of claims 1-3, wherein The acrylate monomer is a difunctional or trifunctional acrylate monomer.

5. The photothermal dual-curing 3D printing ink according to claim 4, wherein The acrylate monomer is selected from at least one of 1,6 - hexanediol diacrylate, tripropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, and tris(2 - hydroxyethyl) isocyanurate triacrylate.

6. The photothermal dual-curing 3D printing ink according to any one of claims 1-3, characterized in that The reactive diluent is selected from at least one of isobornyl methacrylate and 4 - acryloylmorpholine.

7. The photothermal dual-curing 3D printing ink according to any one of claims 1-3, characterized in that, The photoinitiator is (2,4,6 - trimethylbenzoyl) diphenylphosphine oxide.

8. A method for preparing a photo-thermal dual-curing 3D printing ink according to any one of claims 1-7, characterized in that, It includes the following process: Under light - shielding conditions, according to the formula amount, the acrylate monomer, reactive diluent, photosensitive isocyanate monomer, and photoinitiator are mixed and stirred, and then vacuum - degassed to remove bubbles to obtain the photo - thermal dual - curing 3D printing ink.

9. Use of the photo - thermal dual - curing 3D printing ink according to any one of claims 1 - 7 in an interlayer dielectric material.

10. Use of the photo - thermal dual - curing 3D printing ink according to any one of claims 1 - 7 in a wave - transmitting material.

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